FR2781914A1 - Rolling device for public display and advertisement banners with multiple facings rotating in sequence over time - Google Patents

Abstract

The device comprises a band (3) made up of multiple leaves and two alternately rotating parallel rollers (2a,2b) mounted so as to rotate around a frame (1). The rollers are actuated by electric motors (4a,4b) with an anti slip mechanism (7) incorporated.

Description

Device for winding and unwinding a strip.

  The present invention relates to a device for winding and unwinding a strip disposed between two rollers. This type of device is particularly suitable for billboards where messages to be broadcast periodically scroll past a window. To this end, the strip is made up of a series of posters placed between two rollers, the strip winding

  alternately on one or the other of the rollers.

  There are many known winding and unwinding devices

of a band.

  It is known to drive one of the two rollers by a motor and to associate a spring system with the second roller. The spring system will on the one hand ensure the tension of the strip during the unwinding and allow the rewinding of the is strip thanks to the tension that it will have stored. This type of device has many drawbacks. On the one hand because the tension of the strip is not constant since it is generated by the tension of the spring, thus, at the beginning of the unwinding, the strip will be very little taut and at the end will probably be too much. In addition, this system is not adaptable to large bands because the effort

  necessary to rewind the tape could not be provided by a spring.

  It is also known systems where each roller is driven by a different motor. In order to create a resistant torque, the driven motor is generally driven at a lower speed than the driving motor. Such a configuration therefore requires the installation for each motor of a variator of

  frequency which makes such a device bulky and expensive.

  Finally, patent FR 2 659 161 presents a device where one of the rollers is driven by a conventional motor and the other by a torque motor. A torque motor has the characteristic of being able to be driven in the opposite direction to its direction of supply and thus to provide a resistant torque. According to this patent, the torque motor is constantly supplied in the same direction and the other motor rotates alternately in both directions. Thus, when the two motors are supplied in the same direction, the torque motor winds the strip and the other motor unwinds it. When the two motors are supplied in different directions, the torque motor slips since the torque exerted by the other motor is greater, the

  torque motor then creates a resistant torque ensuring the tension of the belt.

  In order to dissipate the overheating created by the slip of the engine, the torque engines are particularly oversized and therefore very bulky. Moreover,

  1o the price of these engines is very high compared to conventional engines.

  The present invention therefore aims to provide a new device for winding and unwinding a strip, ensuring perfect tension of

  the strip, of small bulk and at a lower price than the known systems.

  The invention uses a motor associated with each roller and is characterized in that a torque transmission system adjustable by slipping

is associated with one of the motors.

  Thus, the motor shaft associated with the adjustable torque transmission system can continue to rotate freely when said transmission system slips. Unlike the use of an oversized and therefore costly and bulky torque motor 2 <), the device according to the present invention associating an adjustable torque transmission system allows the use of a conventional motor. The size and cost of such a device

  being significantly lower than that of a torque motor.

  In the following description, the expression transmission system

  torque adjustable by sliding, any system, friction or not, allowing

  transmit an adjustable output torque lower than the input torque.

  Other advantages and characteristics of the invention will become apparent on

  reading of the description below of given embodiments of the invention

  by way of nonlimiting examples and illustrated by the accompanying drawings in which: - Figure 1 shows in front view and in side view the different elements according to the invention. - Figure 2 shows schematically in section the principle of a

electromagnetic clutch.

  As can be seen in Figure 1, the device is composed of a frame io (1) on which are rotatably mounted two rollers (2a) and (2b), the strip (3) is fixed at each of its ends to the rollers. During a display cycle, the strip, for example wound on the roller (2a), will unroll to wind on the roller (2b), then vice versa for the next cycle. The strip is usually made up of a series of posters, each displayed for a preset time. The device is equipped with means not shown making it possible to detect that the poster is in the viewing position. The strip therefore remains stationary for a certain time and is then wound up again to display the next poster. The device according to the present invention is particularly

  suitable for viewing large posters, for example 9m2.

  However, according to the same principle, the device can be adapted to posters

smaller.

  Each roller (2a) and (2b) is driven by a motor (4a) and (4b) possibly associated with a reduction gear (5a) and (5b). According to a preferred embodiment of the invention, the motors can be motors of the type

  asynchronous and worm and wheel type reducers.

  The motors can be connected to the rollers by any type of transmission

  known as belts for example (6a) and (6b).

  One of the motors is associated with a variable torque transmission system by slip (7). This torque transmission system can for example consist of two superimposed discs rubbing against each other, of the "friction clutch >> or even" torque limiter "type. By adjusting the pressure between the two discs we can adjust the slip torque of the system. According to a preferred embodiment of the invention, the torque transmission system is an electromagnetic clutch, the principle of which is

shown in figure 2.

  The electromagnetic clutch is composed of an input shaft (8a) and o0 an output shaft (8b). The input shaft is connected to a motor (4) possibly fitted with a reduction gear (5). The output shaft is connected to the roller transmission system (6). To ensure correct mechanical mounting, an elastic coupling (9) is arranged between the drive shaft and the input shaft (8a) of the transmission system. The input shaft is mechanically linked to a rotor (10). This rotor (10) is generally made of a ferromagnetic material. The output shaft (8b) is mounted on an annular part (11), itself mounted free in rotation on the input shaft (8a) by bearings (12) and (12 '). The annular part (1 1) is equipped on its inner periphery with a

  coil (13) supplied by two brushes (14) and (14 ') fixed relative to the frame (1).

  The coil (13) is therefore arranged in coincidence with the rotor (10). Thus, by known electromagnetic effects, when the coil is powered, an electromagnetic torque is created between the rotor (1 0) and the annular part (1 l). The value of the current supplying the coil allows defining the transmissible torque also called slip torque. The electromagnetic torque transmitted by the clutch depends on the current injected into the coil (13). This current can easily be adjusted by means of a potentiometer placed on the clutch supply circuit. Thanks to such a device, the transmissible torque between the shaft (8a) and the shaft (8b) is adjustable and remains constant in

  time since there is no mechanical friction.

  According to the invention, the engine associated with the torque transmission system will preferably be the low engine (4a). This motor (4a) is permanently controlled in the direction corresponding to the winding of the strip on the

associated roller.

  The high motor can be controlled in both directions of rotation, it may be possible to associate a variable speed drive in order to be able to adjust the

  scrolling speed of the poster.

  Thus, when the high motor is supplied in the same direction as the low motor, the strip is unwound on the high roller (2a) and is wound on the low roller (2b). The winding torque transmitted by the low roller corresponds to the electromagnetic torque defined on the clutch. In order to ensure the tension of the belt, the high motor can optionally be driven at a lower speed than the

i 5 low roll.

  To scroll the strip in the other direction, the high motor (4a) will be supplied in the direction corresponding to the winding of the strip on the high roller (2a). The low motor will continue to rotate in the direction corresponding to the winding of the strip on the low roller. The high engine exerts a torque greater than the electromagnetic torque of the clutch, thus said clutch will slip and will only exert a resistant torque corresponding to the torque.

  electromagnetic which will stretch the poster.

  During the exposure time, the high engine is no longer supplied with power.

  The irreversibility of the reducer (5a) makes it possible to prevent the poster from falling, in addition, it remains tense since the low motor is always powered and that

  the clutch transmits its electromagnetic torque.

  Similarly, in the event of a power failure, the irreversibility of the

  reducer prevents the poster from falling.

  According to many variants known to those skilled in the art, if the reduction gear is reversible or for other reasons, it is for example possible to associate a lack of current brake on the high motor (4a) to ensure the

roller locking (2a).

  The engine control devices are not described in detail, but their construction is perfectly known to those skilled in the art. The two motors can for example be controlled by a programmable automaton managing the exposure times as well as the scrolling speeds. The position of the posters can be easily detected by an optical or inductive system by

  o0 example from a marker placed on the tape.

Claims (4)

Claims   1 / Device for winding and unwinding a strip comprising a strip (3) composed of a series of posters, said strip being wound alternately on two parallel rollers (2a) and (2b) rotatably mounted on a frame (1), each of said rollers being driven by a motor (4a) and (4b) characterized in that a torque transmission system adjustable by slipping   (7) is mounted between one of the motors and the associated roller.   2 / Device according to claim 1 characterized in that the two rollers (2a) and (2b) are horizontal, the torque transmission system (7)   being associated with the low roller (2b).   3 / Device according to claim 1 characterized in that the two rollers (2a) and (2b) are horizontal, the torque transmission system (7)   being associated with the high roller (2a).   4 / Device according to claim 1 characterized in that the system of   torque transmission is an electromagnetic clutch (7).   / Device according to claim 1 characterized in that the torque transmission system is "a friction clutch >> or" a slip torque limiter "composed of several mechanical parts rubbing the relative to each other.   x 6 / Device according to claim 1 characterized in that the motor associated with the torque transmission system (7) is permanently supplied in the direction corresponding to the winding of the strip (3) on the roller it drives. 7 / Device according to claim 4 characterized in that the electromagnetic torque transmitted by the clutch (7) is adjustable using a   potentiometer varying the current in the coil (13).   o10 8 / Device according to claim I characterized in that the engine not comprising the torque transmission system (7) can be controlled in   two directions of rotation and possibly associated with a variable speed drive.   1 5 9 / Device according to claim I characterized in that the motor not comprising the torque transmission system is associated with an irreversible reduction gear (5a) or any other means of blocking the motor shaft, allowing the maintenance of the tape during exposure time or in case of power failure.