MXPA06009003A - Control system for uniform movement of multiple roller shades - Google Patents

Abstract

A system forcontrolling a roller shade having a roller tube windingly receiving a shade fabric varies roller tube rotational speed for constant linear shade speed. The desired linear shade speed, roller tube diameter and shade fabric thickness and length are stored in a memory for use by a microprocessor. Preferably, the roller tube rotational speed is varied by the microprocessor depending on shade position determined by signals from Hall effect sensors. The microprocessor maintains a counter number that is increased or decreased depending on direction of rotation. Based on the counter number, the microprocessor determines shade position and a corrected rotational speed for the desired linear shade speed. Preferably, the microprocessor controls roller tube rotational speed using a pulse width modulated signal. The system may be used to control first and second roller shades having roller tubes of differing diameters or shade fabrics of varying thicknesses.

Description

CONTROL SYSTEM FOR UNIFORM MOVEMENT OF MULTIPLE ROLLER BLINDS FIELD OF THE INVENTION The invention relates to a system for controlling the fabric speed of the curtain for multiple motorized roller curtains.

BACKGROUND OF THE INVENTION Motorized roller curtains include a flexible curtain fabric wound in an elongated roller tube. The roller tube is rotatably supported so that a lower end of the curtain fabric can be raised and lowered by rotating the roller tube. The roller tubes are generally in the form of a right circular cylinder having various lengths to support the curtain fabrics of various widths. Motorized roller curtains include a drive system that couples the roller tube to provide rotation of the tube. For aesthetic reasons, it is desirable that the outer diameter of the roller tube be as small as possible. However, roller tubes are generally supported only at their ends and are otherwise not supported across their length. Therefore, the roller tubes are susceptible to collapse if the cross section of the roller tube does not provide sufficient flexural stiffness for a selected material. Therefore, the increase in the length of a roller tube is generally accompanied by the increase in the outer diameter of the tube. In certain situations, such as for curtain areas of very large width or for curtain areas that are not flat across their width, it may be convenient to use multiple roller curtains. In these situations, it may also be necessary or desirable to use roller tubes with different lengths. Relatively large tubes may require that a larger diameter be used in comparison with smaller tubes in order to limit sinking. Where multiple roller shades are used to obscure a given area, the ability to raise or lower the curtains so that their lower ends move constantly as a unit (ie, simultaneously at the same speed) is desirable. However, two roller shades having different diameter tubes will not raise or lower a curtain fabric at the same speed if they are not rotated at the same rotating speed. For any element that is rotated around a central axis, the linear velocity on a surface of the rotating element will depend on the distance between the surface and the rotating shaft. Thus, for a given rotational speed (i.e., rpm), the resulting linear velocity (ie, cm / sec) on the outer surface of the tube will vary in direct proportion to the diameter of the outer tube. Therefore, two roller tubes having different outer diameters which are driven at the same rotating speed will have different linear speeds at the outer surface. The larger diameter tube will have a higher linear velocity at the outer surface and, similarly, will receive the curtain-related fabric at a higher velocity than the smaller diameter tube in a wound or freed form. The ability to provide a constant curtain velocity for two roller shades having tubes of different diameters is more complicated since the speed of the curtain for any of the roller shades will not remain constant as long as the curtain rises or falls between the two curtain positions. The winding reception of a curtain fabric in a roller tube creates layers of overlapping material that increases the distance between the rotating shaft and the point at which the curtain fabric is received in a coiled fashion compared to the distance in the outer surface of the tube. As a result, the speed of the curtain will vary depending on the thickness of the overlapping layers of material received in the roller tube.

BRIEF DESCRIPTION OF THE INVENTION According to one aspect of the invention, a method for controlling a roller curtain is provided. The roller curtain includes a rotatably supported roller tube that receives a flexible fabric from the curtain in a coiled manner. The method comprises the step of rotating the roller tube to move a lower end of the fabric of the curtain with respect to the roller tube between the first and second curtain positions. The method further includes the step of varying the rotational speed at which the roller tube is rotated during the movement of the curtain fabric so that the speed at which the lower end of the curtain moves remains substantially constant. According to one embodiment, the roller curtain for the method includes a motorized drive system and the speed at which the roller tube is rotated varies depending on the position of the roller curtain. A Hall effect sensor and microprocessor are provided. The microprocessor maintains a count number that increases or decreases in response to the signals from the Hall effect sensor assembly depending on the direction of rotation of an output shaft of the motor. The method further includes the step of assigning a predetermined count number associated with a predetermined curtain position and determining the difference between the counting number in a given curtain position and the predetermined count number. Based on the difference in the counting number, the equivalent number of revolutions of the roller tube and the position of the curtain is determined. According to one embodiment, the curtain fabric related to the method has a thickness and moves between a fully open curtain position and a fully closed curtain position. The method includes the step of selecting a desired linear velocity for the fabric of the curtain and determining a base rotational speed to move the curtain fabric to the desired linear velocity in the fully closed curtain position. The number of revolutions required to move the curtain fabric between fully closed and fully open curtain positions based on the length and thickness of the curtain fabric is then determined. A fully wound radius, which is equal to the distance between the rotating axis for the roller tube and the point at which the curtain fabric is received in a fully unfolded curtain position, is then determined. Based on the fully wound radius, a rotational speed reduction with respect to the base rotational speed necessary to move the curtain fabric to the desired linear velocity in the fully open curtain position is then determined. Preferably, the reduction of the rotational speed required in other curtain positions is then determined by graduating the fully open rotary speed reduction. According to another aspect of the invention, a roller curtain system comprises first and second roller curtains each including a roller tube rotatably supported and a flexible curtain fabric received in a wound manner by the roller tube. Each of the roller curtains further includes a drive system that operably couples the related roller tube to rotate the roller tube in a controlled manner to move a lower end of the fabric of the related curtain between a curtain position. fully open and a fully closed curtain position. Each of the drive systems is adapted to vary the rotational speed at which the related roller tube is rotated. The second roller tube has a diameter that is greater than the diameter of the first tube. The system also includes at least one controller to control the first and second roller shades, the controller adapted to rotate the first roller tube at a rotational speed that is less than that of the second roller tube so that the lower ends of the first and second curtain fabrics move together at substantially the same curtain speed linear. According to one embodiment, each drive system includes a motor having a rotationally driven output shaft. At least one controller is adapted to direct a pulse-width-modulated duty cycle signal to the roller curtain drive systems to vary the rotational speed of the motor output shafts.

BRIEF DESCRIPTION OF THE DRAWINGS For the purpose of illustrating the invention, a form that is preferred herein is shown in the drawings; it being understood, however, that this invention is not limited to the precise arrangement and instruments shown. In the drawings: Figure 1 is a front elevational view of two roller blinds incorporating a curtain speed control system in accordance with the present invention. Figure 2 is a sectional view of one of the roller curtains of Figure 1 taken along line 2-2. Figure 3 is a sectional view of the other one of the roller curtains of Figure 1 taken along the line 3-3. Figure 4 is a graphic illustration showing the speed of the curtain for two roller curtains having roller tubes of different outer diameter driven at a constant rotary speed. Figure 5 is a graphic illustration showing an identical linear curtain speed for the two roller curtains of Figure 4 using the curtain speed control system of the present invention. Figure 6 is a schematic illustration illustrating a curtain speed control system in accordance with the present invention. Fig. 7 is a partial end view showing the Hall effect sensor assembly of the curtain speed control system of Fig. 4. Fig. 8 is a schematic illustration of the pulse trains generated by the sensors of the sensor assembly. of Hall effect of figure 7.

Figure 9 is a flow diagram illustrating a method for controlling the curtain speed for a roller curtain in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS With reference to the drawings, in which like numbers similar elements are identified, a pair of roller blinds 10, 12 respectively including elongated roller tubes 14, 16 which are rotatably supported are illustrated in Figure 1. The roller tubes 14, 16 support flexible fabrics of the curtain 18, 20 which are received in a wound manner in, or released from, an outer surface of the roller tubes 14, 16 depending on the direction in which the tubes roll 14, 16 are rotated. Roller curtains 10, 12 are arranged in a side-by-side manner to provide a combined coverage of a darkened area. In a known manner, each of the roller tubes 14, 16 is rotatably supported to a fixed support such as a wall or ceiling for example. The roller tubes 14, 16, however, are not supported along their lengths between the end supports. Roller tubes having large aspect ratios (ie, length versus outer diameter) are susceptible to subsidence deflections under a combined weight of the tube and a curtain fabric. The use of multiple roller shades, therefore, is desirable to obscure relatively wide darkened areas, since the diameter of each tube can be made relatively small, as compared to that required for a single tube spanning the width, without excessive sinking. As shown, the roller tube 16 is about 2 times as long as the roller tube 14. The aspect ratio for each of the tubes 14, 16 however, has been optimized to provide the tube with smaller diameter than it will not sink excessively when it is supported at its ends and that supports the related curtain fabric 18, 20. Likewise, the outer diameter of the roller tube 16 is greater than that of the roller tube 14, as shown when comparing Figures 2 and 3 In the past, this issue regarding the variation of length for multiple tubes was directed by both tubes that have the larger diameter required for the larger tube. As a result, the shorter of the two tubes can inefficiently have an aspect ratio greater than that needed. Roller curtains 10, 12 include motors 22, 24 which couple the related roller tubes 14, 16 to drive the tubes separately. The present invention provides a control system for driving the curtain fabrics 18, 20 between two positions of the curtain (eg, between fully open and fully closed positions) in a uniform manner so that the lower ends 26, 28 of the curtain fabrics 18, 20 move together at substantially the same speed. The movement of the lower ends 26, 28 of the curtain fabrics 18, 20 is sometimes referred to hereinafter as "curtain velocity". That way of driving the curtain fabrics 18, 20 provides a constant appearance for the lower ends 26, 28 of the curtain fabrics 18, 20 simulating a single fabric of the unitary curtain extending across the width of the darkened area. As described below, in greater detail, the outer diameters differing from the two roller tubes 14, 16 result in different curtain winding characteristics for the tubes 14, 16 thus complicating the desired control for uniform curtain movement. Since the outer tube surface 16 is located at a greater distance from the rotating shaft, compared to the roller tube 14, the linear speed of the outer surface of the tube 16 will be greater than that of the roller tube 14, if the roller tubes 14, 16 are driven at the same rotating speed. As a result, the roller tube 16 will receive, or will release, the curtain fabric at a higher speed than the roller tube 14, if the roller tubes 14, 16 are driven at the same rotating speed. Therefore, in order to provide uniform drive of the curtain fabrics 18, 20, at the same linear speed, the roller tube 16 will need to be driven at a lower rotational speed than the tube 14. Control the roller curtains 10, 12 for uniform curtain speed is further complicated, however, since the winding of each curtain fabric 18, 20 on the outer surface of the related roller tube 14, 16 results in the variation in curtain velocity as the curtain fabrics 18, 20 move between two curtain positions, even if each of the roller tubes 14, 16 is driven at a constant rotary speed. As shown in Figures 2 and 3, the winding reception of the curtain fabrics 18, 20, by means of the roller tubes 14, 16 creates overlapping layers of material, thus varying the distance between the rotary axis and the point in the which the fabric of the curtain 18, 20 is received in a wound manner by the related roller tube 14, 16. As a result, the curtain speed will progressively increase as the curtain fabrics 18, 20 rise or progressively decrease as that the curtain fabrics 18, 20 are lowered, even if each of the tubes 14, 16 is driven at a constant rotary speed. The speed at which the curtain speed will vary will not be the same for roller curtains 10, 12 since a given length of material will form more wound layers in the smaller diameter roller tube 14 that the same length of material will form in the larger diameter roller tube 16. As a result, a given amount of movement for the curtain fabrics 18, 20 will have a greater impact on the curtain speed for the roller curtain 10 than for the roller curtain 12. In relation to the graphic illustrations of figures 4 and 5, the present invention provides a system for controlling the motors 22, 24 of the roller blinds 10, 12 which explains the above-described effects of the diameter of the tube and the thickness of fabric to drive the fabrics of curtain 18, 20 together between the two curtain positions at a substantially constant curtain velocity. Figures 4 and 5 illustrate a location of the hem bar against time. As is well known in the art, the bead bars are located at the lower ends of the curtain fabrics to load the curtain fabrics, thus facilitating the winding of the curtain fabrics. Figures 4 and 5, therefore, illustrate the movement of the lower ends of the curtain fabrics 18, 20 of the roller blinds 10, 12 against time. Figure 4 illustrates the relationship between the movement of the lower end of the curtain fabrics 18, 20 which can result if the roller tubes 14, 16 of the roller blinds 10, 12 are driven at a constant rotary speed. As shown, the bead bar for the roller curtain 12 moves at a faster speed than the bead barrier for the roller curtain 10. The above described effects of the fabric winding having a curtain speed are also illustrate If the curtain speed were constant for the roller curtains 10, 12 the resulting ratio for each of the roller tubes 14, 16 could appear as a straight line. However, since the winding receiving point moves outward from the rotating shaft due to the winding effect of the fabric, the relationship is not linear. In fact, the curves are turned upwards for each of the roller blinds 10, 12 to illustrate that the curtain speed for each one increases with time. Figure 5 illustrates the curtain speed that results when the roller curtains 10, 12 are operated using a curtain speed control system 30 in accordance with the present invention. As described below, the control system 3 varies the rotational speed at which the roller tubes 14, 16 of the roller curtains 10, 12 are driven as the related curtain fabrics 18, 20 move between two. curtain positions. As shown, the resulting curtain velocities for roller curtains 10, 12 are substantially identical. Also, as shown, the curtain speeds for roller curtains 10, 12 are substantially linear. Referring to Figure 6, the roller curtain control system 30 in accordance with the present invention is illustrated schematically. The following description for the control system 30 relates only to the roller curtain 10, it being understood that a similar control system can be used to control the roller curtain 12. The control system 30 includes a Hall effect sensor assembly. , connected to the motor 22 to provide information regarding the rotary speed and direction for the output shaft of the motor 34. As shown in FIG. 7, the Hall effect sensor assembly 32 includes a sensor magnet 36 secured to the output shaft 34 of motor 22 and Hall effect sensors 38 are identified as sensor 1 (S1) and sensor 2 (S2). The sensors 38 are located adjacent the periphery of the magnet 36 and are separated by 90 degrees. The sensors 38 provide output signals in the form of pulse trains. The frequency of the pulses is a function of the rotational speed of the output shaft of the motor 34. The relative spacing between the two pulse trains is a function of the rotary direction. When the fabric of the related curtain 18 is driven in an upward direction corresponding to the motor direction shown in Figure 7, the pulse trains of the sensors 1 and 2 are in relative positions shown in the figure 8, with sensor 1 leading sensor 2 90 degrees out of phase. Referring again to FIG. 6, the control system 30 includes a microprocessor 40 that is operably connected to the Hall effect sensor assembly 32 to receive pulse train signals generated by the rotation output shaft. As described below in greater detail, the microprocessor 40 uses the information with respect to the rotation of the motor shaft 34 to track the position of the curtain fabric 18 as it moves between the two curtain positions. The microprocessor 40 is coupled to a memory 42. The microprocessor directs the motor control signals 44, 45 to the motor 22, preferably via a bridge circuit H 46. The control signal 44 directs the motor to brake or to rotate the roller tube 14 in one of the opposite directions. The control signal 45 is a pulse width modulated signal of 20kHz which controls the duty cycle of the motor 22 for variation in the rotational speed of the motor. The variation in the rotary speed of the motor using a modulated duty cycle signal of pulse amplitude is shown and described in the U.S. patent. No. 5,848,634. As described, the microprocessor of the '634 patent directs a 2 kHz duty cycle signal to a PWM circuit. The PWM circuit reads the duty cycle signal from the microprocessor as an average DC level and uses it to set the pulse amplitude of a 20kHz modulated pulse width signal directed to the motor. In the present invention, a pulse amplitude modulation circuit between the microprocessor and the motor is not used. In fact, the microprocessor 40 generates the PWM signal directly. Modulation of the pulse amplitude for a variable motor speed is preferred herein. The present invention, however, is not limited to a variable motor speed by pulse width modulation. Referring to Figure 9, a method for controlling the curtain speed for each of the roller curtains 10, 12 is schematically illustrated. For simplicity, only the roller curtain 10 will be included in the following description, it being understood that the control The curtain speed for roller curtain 12 can be achieved in the same way. As described above, the linear velocity at a point of a rotation element depends on the distance between the point and the rotary axis for the element. For a roller tube, the linear velocity on the outer surface of the tube is related to the rotational velocity in accordance with the equation: Linear velocity = rotational velocity x circumference of the outer tube In a first step 48, the values representing the size of the roller tube 14 (i.e., outside diameter), the thickness of the fabric of the related curtain 18, the length of the fabric of the curtain 18 (i.e., the length of material to be wound on the roller tube 14 between the fully closed position and the fully open position) and the desired linear speed for the fabric of the curtain 18 are introduced. This information may be placed in storage in the memory 42 and, therefore, this step only needs to be performed once as part of an installation procedure. A portable programmer or computer running in a graphical user interface program can be connected to the system 30 to facilitate the entry of information. Based on the above equation, and the input values for the size of the roller tube 14, and the desired linear speed, the microprocessor 40 in step 50 determines the rotational speed necessary for the roller tube 14 to receive in a coiled manner the fabric of the curtain 18 in the completely closed curtain position (ie, at a distance from the rotary axis equal to the outer surface of the tube). This rotational speed related to the initial reception of the fabric of the curtain 18 by the roller tube 14 is sometimes referred to herein as "base RPM" or "base rotational speed". In step 52, the microprocessor 40 calculates the number of revolutions of the roller tube 14 necessary to wind the length of the fabric of the curtain 18 in the roller tube 14. As described above, the distance between the rotating shaft and the at which point the fabric of the curtain 18 is received in a wound manner in the roller tube 14 will increase from the fully closed position due to the overlapping layers of material. In step 54, the microprocessor 40 calculates the increase in this distance, hereinafter sometimes referred to as the "radius fully wound" based on the input value for the thickness of the fabric of the curtain 18 and the number of revolutions calculated in step 52. Using the above equation relating the rotary speed with the linear speed, the microprocessor 40, in step 56, calculates the reduced rotating speed which will drive the fabric of the curtain 18 at the desired linear speed for the largest fully open radius (hereinafter, "RPM fully wound "). Thus, the total amount by means of which the rotating speed will need to be reduced by means of the control system 30 during winding of the fabric of the curtain 18 to maintain a constant linear velocity is equal to the difference between the base RPM and the RPM totally wound. The distance between the rotary axis and the winding receiving point of the fabric of the curtain 18 will vary depending on the position of the curtain. This distance will be equal to the outer radius of the tube when the fabric of the curtain 18 is located in the fully closed position and will be equal to the radius fully wound in the fully open position. According to the method of Figure 9, the microprocessor 40 in step 58 tracks the position of the curtain fabric 18 by adding or removing revolutions of the motor output shaft 34 or a proportional number of the edge signals of the effect Hall, to a count number maintained by the microprocessor 40 depending on the direction of rotation. The microprocessor 40 in step 60 determines the difference between the current count number and a predetermined count number that is related to the fully closed position. The difference of the count number is then divided in step 62 between the number of revolutions of the tube, or the proportional number of the edge signals of the Hall effect, necessary to wind the total length of the fabric of the curtain 18. The percentage The resultant is then multiplied by the length of the curtain to determine the position of the curtain (ie, the linear distance between the fully closed position and the current position). Based on the current curtain position determined in step 62, the microprocessor 40 in step 64 determines the corrected RPM upon graduation of the complete winding correction, which is equal to the difference between base RPM and fully wound RPM. For example, if the current curtain position is closed three-fourths, the corrected RPM can be determined by subtracting 25 percent of the correction fully wound from base RPM. The microprocessor 40 in step 66 then directs the circuit PWM 44 to set the rotary speed for the related motor 22 to the corrected rotational speed determined by the microprocessor 40 in step 64. The above described steps are repeated in a cyclic mode during the movement of the curtain fabric related to the microprocessor 40 periodically updating the current curtain position and recalculating the corrected rotational speed based on the position of the current curtain.

Referring again to FIG. 1, the motor 22 for the roller curtain 10 is located on the left side of the roller tube 14 and the motor 24 for the roller curtain 12 is located on the right side of the roller tube 16. Assigning the motors 22, 24 in opposition to each other in this manner desirably limits the space separating the curtain fabrics 18, 20. In addition, it is desired that both curtain fabrics 18, 20 be wound from the same side as the roller tubes 14, 16 (ie, on the front sides of the opposite roller tubes 14, 16 from the darkened area). For this to happen, however, the motors 22, 24 must be driven in opposite rotating directions. As described above, the program microprocessor 40 to maintain a count by adding or decreasing the axis revolutions, or a proportional number of the Hall effect edge signals, depending on the direction in which the motor shaft is rotated. . Since the desired simultaneous movement of the two curtains requires opposite rotation of the motor, the descent of the curtain fabrics 18, 20 from the fully open position will result in an increase in the counting number for one of the roller curtains 10, 12 and a corresponding decrease in the other. Therefore, it is desired that the preset count number relating to the fully open position be large enough so that the resulting count number in the fully closed position is positive for both roll curtains 10, 12.

In the method described above, the rotary speed for the motors 22, 24 is corrected by resetting the position of the curtain in a cyclic mode during the movement of the related curtain fabrics 18, 20 and periodically determining a corrected motor speed for the engines 22, 24. The present invention is not limited to the control of engine speed using this method. It is within the scope of the invention to control the speed using other methods. For example, the microprocessor of the roller curtain can be programmed to control the motor speed based on the amount of time it can take to move the curtain between the two curtain positions at the linear input speed. As described above, the corrected motor speed will increase or decrease depending on whether the curtain is open or closed. Using a time measurement method, instead of the position tracking method described above, the microprocessor can determine the total amount of motor speed correction to be applied upon graduation from the fully wound correction. For example, the curtain movement between the fully closed position and the three-quarter closed position may require that the motor speed be reduced 25% from the fully wound correction. The microprocessor can direct the PWM circuit to reduce the speed of the motor by the amount required in an equal manner during the amount of time in which the curtain moves, The curtain speed control system of the present invention is described above in relation to the winding problems for multiple curtains created when the pipes have different external diameters. Those skilled in the art will recognize that similar winding problems will be present when multiple roller curtains support curtain fabrics having different thicknesses. This will be true even if the outer diameter of the roller tubes is identical since the distance between the rotating shaft and the winding receiving point will increase rapidly for the roller curtain supporting the thicker curtain fabric. In the above-described embodiments of the invention, the rotating speed of the roller tube varies to provide a substantially constant speed for the related curtain fabric. The present invention, however, is not limited to the constant curtain speed. It is within the scope of the present invention, for example, to vary the rotating speed for the roller tube to provide a non-constant curtain velocity wherein the curtain varies in accordance with a desired ratio. The foregoing describes the invention in terms of modalities provided by the inventors for which an authorized description was found available, although the non-substantial modifications of the invention, not provided herein, may nonetheless represent equivalents thereof.

Claims (20)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for controlling a roller curtain having a roller tube supported in a rotating manner that is received in a coiled manner by a flexible fabric of the curtain, the method comprising: rotating the roller tube to move a lower end of the roller fabric of the curtain between the first and second curtain positions; and varying the rotating speed at which the roller tube is rotated during the movement of the curtain fabric.

2. The method according to claim 1, further comprising: providing a motor having a rotationally driven output shaft operably connected to the roller tube to rotate the roller tube; and controlling the motor to vary the rotating speed of the output shaft during the movement of the curtain.

3. The method according to claim 1, further characterized in that it comprises moving the lower end of the fabric of the curtain up or down with respect to the roller tube depending on the direction of rotation for the roller tube, and varying the rotational speed at which the roller tube is rotated by increasing the rotational speed during the downward movement of the lower end of the curtain fabric and by decreasing the rotational speed during upward movement of the lower end of the fabric of the curtain; curtain.

4. The method according to claim 2, further characterized in that it comprises: directing a work-cycle signal modulated with pulse amplitude to the motor to establish a particular rotational speed for the output shaft of the motor; and modifying the pulse amplitude of the pulse amplitude duty cycle signal to vary the rotational speed of the output shaft of the motor.

5. The method according to claim 4, further characterized in that it comprises: providing a controller adapted to generate the pulse width working cycle signal and an H-bridge circuit between the controller and the motor.

6. The method according to claim 1, further characterized in that the rotational speed of the roller tube varies so that the speed of the linear curtain is substantially constant.

7. A method for controlling a roller curtain having a roller tube supported in a rotating manner, the roller tube receives a flexible fabric from the curtain in a coiled manner, the method comprising: providing a drive system including an engine which operably couples the roller tube to rotate the roller tube, the actuation system adapted to vary the rotational speed at which the roller tube is rotated; directing the drive system to rotate the roller curtain to move a lower end of the curtain fabric with respect to the roller tube; determine the position of the lower end of the curtain fabric; and directing the drive system to vary the rotational speed at which the roller tube is rotated depending on the position of the lower end of the curtain fabric.

8. The method according to claim 7, further characterized in that the motor of the drive system includes a rotating drive shaft, the method further comprising: providing a Hall effect sensor assembly located adjacent to the output shaft of the motor for generate a Hall effect signal during rotation of the motor output shaft to determine shaft revolutions; providing a microprocessor adapted to receive the Hall effect signal from the sensor assembly and to maintain a count number that increases or decreases depending on the direction of rotation of the output shaft of the motor; assigning a predetermined count number related to a predetermined curtain position for the curtain fabric; determine the difference between a current count number related to a current curtain position and the predetermined count number; determining the number of revolutions of the roller tube between the given curtain position and the predetermined curtain position which is equivalent to the difference of the counting number; and determining the current curtain position based on the equivalent number of revolutions of the roller tube.

9. - The method according to claim 8, further characterized in that the predetermined curtain position is the fully closed curtain position.

10. The method according to claim 9, further characterized in that the fabric of the curtain moves between the fully open curtain position and a fully closed curtain position, and wherein the counting number related to the curtain position Fully open is large enough to provide a positive count number without considering whether the count number increases or decreases during the movement of the curtain fabric between fully open and fully closed curtain positions.

11. The method according to claim 7, further characterized in that the fabric of the curtain has a thickness and moves between the fully open curtain position where a length of the fabric of the curtain is received in a manner wound by the curtain. Roller tube and fully closed curtain position, the method further comprises: selecting a desired linear velocity for the curtain fabric; determining a base rotating speed to move the fabric of the curtain to the desired linear velocity in the fully closed curtain position; determine the number of revolutions of the roller tube required to move the fabric of the curtain between fully closed and fully open curtain positions based on the length and thickness of the curtain fabric; determining a radius that is totally winding that is equal to the distance between a rotating shaft for the roller tube and the point at which the curtain fabric is received in a fully unfolded curtain position; and determining a rotational speed reduction with respect to the base rotating speed that is necessary in the fully open curtain position to move the curtain fabric to the desired linear speed.

12. The method according to claim 11, further characterized in that it comprises: determining a rotary speed reduction graduated with respect to the base rotating speed based on the position of the curtain fabric; and directing the drive system to adjust the rotational speed at which the roller tube is rotated based on the graduated rotational speed reduction.

13. The method according to claim 7, further characterized in that the rotational speed of the roller tube varies so that the linear speed at which the lower end of the fabric of the curtain moves is substantially constant.

14. A roller curtain system comprising: first and second roller curtains, each including a roller tube supported rotatably in a flexible curtain fabric that is received in a wound manner by the roller tube, each roller curtain further includes a drive system operably engaging the related roller tube to rotate the roller tube in a controlled manner for movement of a lower end of the curtain fabric related between a fully open curtain position and a fully closed curtain position, each of the drive systems adapted to vary the rotational speed at which the related roller tube is rotated, the second roller tube has an outer diameter that is greater than the outer diameter of the first tube of roller; and at least one controller for directing the first and second drive systems for rotating the first and second roller tubes, the controller adapted to direct the first drive system for rotating the first roller tube at a rotating speed which is smaller than the rotating speed at which the second roller tube is rotated by the second drive system so that the lower ends of the first and second curtain fabrics move together at substantially the same linear curtain speed.

15. The roller curtain system according to claim 14, further characterized in that the drive system of each roller curtain includes a motor having an output shaft that is rotationally driven and wherein at least one controller is adapted to drive a modulated duty cycle signal of amplitude of pulse to the roller curtain drive systems to vary the rotational speed of the motor output shafts for the drive systems.

16. The roller curtain system according to claim 15, further characterized in that each roller curtain further includes an H-bridge circuit between the motor of each drive system and at least one controller.

17. - A roll curtain system that. it comprises: first and second roller blinds, each including a roller tube supported in a rotatable manner and a flexible fabric of the blind that is received in a wound manner by the roller tube, each roller blind also includes a drive system which operably coupling the related roller tube to rotate the roller tube in a controlled manner for movement of a lower end of the fabric of the related curtain between a fully open curtain position and a fully closed curtain position, each of the drive systems adapted to vary the rotational speed at which the related roller tube is rotated, the second fabric of the curtain has a thickness that is greater than the thickness of the first curtain fabric; and at least one controller for directing the first and second drive systems for rotating the first and second roller tubes, the controller adapted to steer, the first drive system for rotating the first roller tube at a rotational speed that is less than a rotating speed at which the second roller tube is rotated by the second drive system so that the lower ends of the first and second curtain fabrics move together at substantially the same linear curtain speed.

18. The roller curtain system according to claim 17, further characterized in that the drive system of each roller curtain includes a motor having an output shaft rotationally driven and wherein at least one controller is it adapts to direct a pulse-modulated duty cycle signal to the roller curtain drive systems to vary the rotational speed of the motor output shafts for the drive systems.

19. The roller curtain system according to claim 18, further characterized in that each roller curtain further includes an H-bridge circuit between the motor of each drive system and at least one controller.

20. A method for controlling a roller curtain having a roller tube supported in a rotating manner that receives a flexible fabric from the curtain and a motor having an output shaft rotatably rotated to rotate the tube. of roller to move the fabric of the curtain between a fully open position and a fully closed position, the method comprises: providing at least one Hall effect sensor adapted to generate signals representing the rotation of the output shaft of the motor; providing the microprocessor adapted to receive the signals from at least one Hall effect sensor and to maintain a count number that increases or decreases depending on the direction of rotation for the output shaft of the motor; relate a counting number to the fully open position of the curtain, the counting number related to the fully open position that is large enough to provide a positive counting number during any movement of the curtain without considering whether the counting number is increased or decreases during the movement of the fabric of the Curtain curtain position fully open.