Motor-driven roll screen

Abstract: A motor-driven roll screen has a limit switch (5) mounted at its lower weighted end so that the switch (5) is actuated when the lower end of the screen (1) meets an obstruction, the screen (1) having a conductor (7) located along its side edge to connect the limit switch (5) to an arrangement at the top of the roll screen for winding or unwinding the roll screen.

Description: The present invention relates to a motor-driven roll screen including a winding roll and a screen sheet or blind connected at its upper end to said winding roll, said winding roll being driven by an electric motor to wind up said screen sheet thereon or to unwind said screen sheet therefrom, to open or close the roll screen. In the roll screen of the above type, the screen sheet is lowered by rotating the winding roll in sheet unwinding direction. If the rotation of the winding roll is continued in its sheet lowering direction after a weight bar attached to the lower end of the screen sheet (which serves to hold the screen sheet in stretched state) has come into contact with a floor surface, the screen sheet becomes slackened, so that the appearance of the roll screen becomes injured. Such problem may be solved by adjusting the full length of the screen sheet to be precisely equal to the height of the fixing position of the winding roll from the floor surface. However, such adjustment of the full length of the screen sheet according to the height of the fixing position of the screen sheet requires a troublesome work. Furthermore, if the weight bar comes into contact with some obstacle existing in the lowering path of the screen sheet, the weight bar becomes tilted to the left or the right, depending upon the position of the obstacle, even if the lowering of the screen sheet is stopped. If the lowering of the screen sheet is not stopped after the weight bar has come into contact with the obstacle, the screen sheet becomes inflated while tilting to the left or to the right. When the weight bar attached to the lower end of the screen sheet comes into contact with some obstacle as described above, the appearance of the roll screen is largely injured and, moreover, the screen sheet itself or the operating mechanism therefor may be damaged. In order to solve such problem, it has been proposed to provide a limit switch which is actuated by the weight bar coming into contact with the floor surface or the obstacle, thereby controlling the rotation of the winding roll. Such a solution can be found in French Patent Specification No. FR-A-2385880. However, the arrangement described in this prior specification has a number of disadvantages. In particular the conductor for connecting the limit switch with the rotation control means is likely to become stressed during repeated use. Thus in accordance with the present invention there is provided a motor driven retractable blind comprising a winding roll, a blind member having a weight bar attached to its lower end, an electric motor for raising or lowering said blind member, a limit switch arranged to be actuated when said weight bar contacts an obstacle, at least one signal transmitting conductor secured to the blind member for connecting said limit switch to winding control means to control rotation of said winding roll in response to signals from said limit switch, and characterised in that said signal transmitting conductor comprises a cable secured along an edge of said blind member, and in that said winding roll comprises an inner core shaft driven by said motor and a concentric outer shaft connected to said blind member, said outer shaft being shorter than said inner shaft so that said inner shaft projects beyond said outer shaft by a distance at least equal to the width of said signal transmitting conductor, and further in that said signal transmitting conductor is connected to a contact spring biased into permanent electrical contact with an annular fixed contact relative to which said inner and outer shafts rotate when said blind member is wound either up or down, the arrangement being such that when said blind member is wound up said signal transmitting conductor forms a plurality of layers in the space provided by the projecting end of the inner shaft. The invention will be explained with reference to the accompanying drawings which illustrate a preferred embodiment of the invention, in which: Fig. 1 is a front view showing an embodiment of the motor-driven roll screen according to the present invention; Fig. 2 is an enlarged front view, partly broken, of a part of the embodiment shown in Fig. 1; Fig. 3A is a sectional view showing the lowered state of a roll screen sheet; Fig. 3B is a partial view showing the state where the roll screen sheet has come into contact with an obstacle; Fig. 4A is a sectional view showing a side edge portion of an example of the roll screen sheet; Fig. 4B is a sectional view showing a side edge portion of another example of the roll screen sheet; and Fig. 5 is an exploded perspective view showing a connection of an upper part of a signal transmitting conductor. Now, description will be given to an embodiment of the present invention, with reference to the drawings. Fig. 1 is a front view showing a preferred embodiment of the present invention, which includes a roll screen sheet 1, a motor-driven winding roll 2, a weight bar 3 attached to the lower end of said screen sheet 1, and supporting members 4 for supporting the winding roll 2. According to the present invention, a limit switch 5 is attached to the weight bar 3, as shown in Fig. 2, which is arranged to be actuated by the weight bar 3 coming into contact with a floor surface or an obstacle which may exist in the lowering path of the screen sheet 1 when the screen sheet 1 is lowered by rotating the winding roll in its unwinding direction. In the illustrated embodiment, the limit switch 5 is arranged at each end of the weight bar 3, and an obstacle sensing member 6 connected between the limit switches 5 at the both ends of the weight bar is slidably mounted in the weight bar in vertical direction, so that said obstacle sensing member can sense an obstacle which exists at any position between the both ends of the weight bar. A signal transmitting conductor 7 is attached to said screen sheet along a side edge thereof throughout a full length thereof. The signal transmitting conductor 7 may be attached to the screen sheet by fixing a strip having the signal transmitting conductor 7 onto the side edge of the screen sheet 1, as shown in Fig. 4A, or adhering the signal transmitting conductor 7 in the form of a flat cable directly onto the side edge of the roll screen sheet. The lower end of the signal transmitting conductor is connected with the limit switch 5, as shown in Fig. 2, and the upper end of said conductor is connected through a rotary sliding contact means (as hereinafter described) to a winding roll rotation control device 8 as shown in Fig. 1. The control device 8 is turned ON or OFF by an operating switch 9. The connection between the upper end of the signal transmitting conductor and the rotation control device 8 is formed, for example, by fixed contact members 12 disposed in a stationary part consisting of a fixed shaft 10 supported by the supporting member 4 and a contact receiving shaft 11 and movable contact members 13 disposed in the winding roll 2 rotatably supported on said stationary part. The fixed contact members 12 and the movable contact members 13 are held in pressed contact with each other under the action of springs 14 to constitute the rotary sliding contact means to transmit an electric signal. The movable contact members 13 are supported by a contact adapter 15. As explained above, the roll screen according to the present invention is so constructed that when the weight bar 3 comes into contact with any obstacle, the contact is detected by the limit switch and the signal is transmitted through the rotary sliding contact means to the rotation control device, which controls the rotation of the winding roll. In the embodiment as shown in Fig. 2, the winding roll 2 consists of an inner core shaft or a core pipe 2a driven by the electric motor and an outer shaft or a screen sheet fixing pipe 2b fixedly fitted on the outside of said core pipe to which said roll screen sheet is fixed. A length of said screen sheet fixing pipe 2b is shorter than that of the core pipe 2a to form, at its end, a space having a width at least equal to a transverse width of said signal transmitting conductor, while a radius of the screen sheet fixing pipe 2b is larger than that of the core pipe 2a to form the space having a radial size at least equal to a total thickness of the signal transmitting conductor which has been completely wound up on the winding roll. According to this embodiment, the total thickness of the superposed signal transmitting conductor when the roll screen sheet has been completely wound up on the winding roll is housed in the space formed at the end of the screen sheet fixing pipe, so that no convex portion is formed on the surface of the screen sheet which has been completely wound up onto the winding roll. The numeral 16, in Fig. 2, designates a cap, and the numeral 17, in Fig. 5, designates a motor pipe. In the illustrated embodiment, the limit switches are mounted on the both ends of the weight bar and the signal transmitting conductors 7 are attached to the roll screen sheet along both side edges thereof. The upper end portions of these signal transmitting conductors are collected at one end of the winding roll and connected through the rotary sliding contact means to the control device. When the weight bar comes into contact with the obstacle, the electric circuit contained in the limit switch is actuated, whereby a signal current passes to stop rotation of the electric motor. The two signal transmitting conductors are connected in parallel, so that if only one of the switches is actuated the lowering of the roll screen sheet is stopped at once. As explained above, the present invention provides the motor-driven roll screen which is arranged to immediately stop lowering of the roll screen sheet when the weight bar comes into contact with a floor surface or any obstacle 18 existing in the lowering path of the roll screen sheet, as shown in Fig. 3B. Accordingly, the roll screen is prevented from injuring its appearance or producing any damage of the screen sheet or the operating mechanism therefor.

Claims: A motor driven retractable blind comprising a winding roll (2), a blind member (1) having a weight bar (3) attached to its lower end, an electric motor for raising or lowering said blind member, a limit switch (5) arranged to be actuated when said weight bar contacts an obstacle, at least one signal transmitting conductor (7) secured to the blind member for connecting said limit switch to winding control means (8) to control rotation of said winding roll in response to signals from said limit switch, and characterised in that said signal transmitting conductor comprises a cable secured along an edge of said blind member, and in that said winding roll comprises an inner core shaft (2A) driven by said motor and a concentric outer shaft (2B) connected to said blind member, said outer shaft being shorter than said inner shaft so that said inner shaft projects beyond said outer shaft by a distance at least equal to the width of said signal transmitting conductor, and further in that said signal transmitting conductor is connected to a contact (13) spring biased into permanent electrical contact with an annular fixed contact (12) relative to which said inner and outer shafts rotate when said blind member is wound either up or down, the arrangement being such that when said blind member is wound up said signal transmitting conductor forms a plurality of layers in the space provided by the projecting end of the inner shaft. A retractable blind according to claim 1, and further characterised in that there is a limit switch at each end of said weight bar, each limit switch having an associated signal transmitting conductor secured to the associated edge of said blind member.

Inventors: OGAWA HIDEHIRO, OGAWA, HIDEHIRO
Applicants: NICHIBEI KK, KABUSHIKI KAISHA NICHIBEI
Application year: 1990
Main classification: E06B9
IPC codes: E06B9