US3089664A - Mechanism for automatically blocking a lifting roller in venetian blinds - Google Patents

Description

May 14, 1963 H. FABER 3,

MECHANISM FOR AUTOMATICALLY BLOCKING A LIFTING ROLLER I ENETIAN BLINDS Filed June 1960 INVENTOR HARRY FABER BY W.

ATTORNEY.

llnite States arent Patented May 14, 1963 ice 3,089,664 MECHANISM FOR AUTOMATICALLY BLOCKING A LIFTING ROLLER IN VENETIAN BLINDS Harry Faber, Ryslinge, Denmark, assignor to A/S Chr.

Fabers Fabriker, Ryslinge, Denmark Filed June 16, 196i), Ser. No. 36,553

Claims priority, application Denmark June 19, 1959 2 Claims. (Cl. 2.4299) My invention relates to a mechanism for automatically blocking a roller for a lifting cord or a lifting band in a Venetian blind.

In many cases the raising of a blind is eiiected in the way that two or more lifting cords or lifting bands are connected with the bottom rail of the blind, and from there are passed upwards through apertures in the individual blind slats, placed vertically one above another, and in the head rail of the blind are passed over a corresponding number of rollers, on which the cords or bands are wound, and which are positioned on a common horizontal shaft, which is mounted in the head rail and by some operating mechanism rotated in one direction or the other to effect raising and lowering, respectively, of the blind.

When Venetian blinds are lowered, especially larger ones, as e.-g. those used for shop windows, it may happen that the bottom rail of the blind strikes against an obstruction, so that one or more of the cords or bands are relieved of their weight and by continued unwinding from the lifting roller become entangled with other things or with themselves or are otherwise disarranged. This is especially so, when steel cords or steel bands, which among other things may easily kink, are used for raising the blind.

Attention has already before been fixed on this problem, and several securing mechanisms have been suggested in the form of blocking members, which operate when the cords or bands are relieved and arrest the continued lowering movement of the lifting roller. Such blocking members have been brakes or stops, which are kept in inactive position by the tight cord or the tight band, but are put into active position under the influence of a compression spring or a tension spring when the cord or band is relieved, and prevent a continued movement of the roller in the lowering direction, until the obstruction, which caused the cord or the band to be relieved, has been removed, and the cord or band again tightens.

The said known securing mechanisms have proved to possess the substantial disadvantage that they are not operationally reliable on account of the springs used, which partly are exposed to damage, partly lose their spring power in the course of time or because of deposits of dirt.

The primary object of the present invention is to remedy the above mentioned drawback by providing a mechanism, which is so positioned that it is not exposed to damage. Another object is to provide a mechanism which preserves its operational reliability irrespective of the passing of time.

Still another object is to provide a reliable mechanism, in which the force necessary to move the blocking member into its active position is always present in the form of the own weight of the member.

A further object of my invention is to provide a mechanism including a blocking member which is well and safely guided in its movements.

A still further object is to provide a mechanism which is well protected against dirt and damage.

Other objects of my invention will appear from the following description taken in conjunction with the accompanying drawings, which describe and show my invention by way of illustration.

In the drawing,

FIGURE 1 is a side elevation of a mechanism embodying a preferred form of my invention, with the blocking member in its inactive position,

FIGURE 2 is a similar side elevation, but with the blocking member in its active position, and

FIGURE 3 is an enlarged sectional view on the lines III'III of FIGURE 2.

Between two transverse walls 2 and 4, which are fixedly positioned in a head rail '5 of a Venetian blind, there is disposed a roller 6 for a lifting cord or a lifting band, such as a steel band 8. This band is attached below to the bottom rail of the blind, not shown, and is passed up through apertures in the blind slats, not shown, and through an aperture 9 in the bottom of the head rail 5 into the space between the partitions 2 and 4, where it is wound on the roller 6, which is fixedly disposed on a longitudinal shaft, such as a hexagonal shaft 10, by the rotation of which the blind can thus be raised and lowered.

The roller 6 has an annular recess 12., which is open towards the plate 2, and wherein a blocking member 14 with arched lateral arms 16 and 18 is loosely disposed, said arms having a certain radial clearance in the recess 12. The blocking member 14 is locked against movement in the peripheral direction of the roller 6 by means of a projection Ztl, which is radially displaceable in an aperture 22 in the surface of the roller 6. Furthermore, the blocking member 14 has a stop 24, protruding in the axial direction of the roller 6. The plate 2 is provided with a central opening 26, which has such a size and shape that the roller 6 with the blocking member 14 and the stop 24, provided thereupon, may freely complete a full rotation, when the blocking member 14 is in the innermost position shown in FIG. 1. When on the contrary the blocking member occupies the outermost position shown in FIGS. 2 and 3, the stop 24 will strike against a radial facing or ledge 28 at the outermost edge of the aperture 26 and thereby prevent a continued rotation of the blocking member 14- and consequently of the roller 6.

The mechanism works as follows. During normal lowering of the blind with the band tightened as shown in FIG. 1 by anticlockwise rotation of the shaft 10, the band 8 which is tightly wound on the roller 6 will force the projection 20 inwards and thereby keep the blocking member 14 with the stop 24 in its innermost position, shown in FIG. 1, whereby the blocking member 14 is rotated together with the roller 6, the stop being unobstructed in its rotation. If the part of the bottom rail of the blind, which is carried by the band 8, strikes against any obstruction during the lowering, the band 8 is relieved, and this relief is immediately transmitted to the windings on the roller 6, which on the lowermost side of the roller 6 move away from its surface. When, therefore, during its rotation with the roller 6 the blocking member 14 for the first time following arrives in its lowermost position as shown in FIGS. 2 and 3, it will by its own weight fall down into its outermost position, in which the stop 24 will strike the ledge 28 and thereby prevent a continued rotation of the roller 6 and consequently of the shaft 10, so that the operators attention is turned to the obstruction, which can be removed, and thereafter without hindrance the roller 6 may-if necessary after having been turned slightly back in order to tighten the band 8 and the abutment of the band windings against the roller-be turned again in the direction corresponding to lowering, the blocking member being then forced into its inactive position as shown in FIG. 1.

The mechanism according to the invention also operates to prevent a continued rotation of the shaft 10 and consequently of the roller 6, when the bottom rail of the blind has arrived in its lowermost position, which may be determined by a window sill or a floor under the window or by the length of the ladder tape of the blind, in which case the band 8 is also relieved. The mechanism may be placed at each of the lifting rollers of the blind or at one or several thereof, preferably the two outermost rollers on the blind.

Even if the mechanism according to the invention is of particular importance for larger Venetian blinds, e.g. blinds for shop windows, where it is often impossible from the place of operation to watch the movement of the blind during lowering, it is also with great advantage useful for smaller blinds, where obstructions in the lowering path of the blind may as well occur, which may disarrange the lifting band.

The mechanism according to my invention may be altered in many ways without departing from the invention. Thus, it is not necessary that the lifting roller be positioned between transverse walls, one of which forms the facing for the stop on the blocking member, but said stop may be arranged to cooperate with any other suitable fixed facing. The blocking member may also have a shape and position different from those shown in the drawing. The main thing is that the blocking member solely by the action of its own Weight can move into its active blocking position. It is natural that the blocking member should have a certain weight, but precisely this fact in connection with the very simple construction produces a robust mechanism, which will stand undamaged even the roughest treatment, to which a Venetian blind may be exposed in operation.

It is to be understood that various other modifications and departures from the construction described may be made; and I do not wish in any way to limit myself to the exact details and mode of operation set forth in this specification and drawing, for it will be obvious that wide departure may be made without departing from the spirit and scope of my invention as set forth in the appending claims.

I claim as my invention:

1. In a mechanism for automatically blocking a roller for a lifting band of a Venetian blind, comprising a lifting band, at least one facing member, a roller positioned in said facing member and having a circular recess in one of its ends, a fixed stop on said facing member, a blocking member displaceable inwardly by said band when wound on said roller and in outwardly radial direction with respect to said roller to cooperate with said fixed stop when the band is relieved, and slidably movable into blocking position solely by the action of its own weight, said blocking member being loosely disposed with a certain radial clearance with respect to said roller in said recess and positioned beneath the surface of said roller face, said recess being shaped as a circular arc and being concentrical with the axis of said roller, and lateral arms shaped as circular axis on said blocking member and having a. projection guided in an aperture in the roller face, a stop on the blocking member protruding in the axial direction of the roller, said last mentioned stop striking against said fixed stop in the outermost position of the blocking member clear of the same in the innermost position thereof.

2. In a mechanism according to claim 1, said facing member comprising a radial ledge on the lowermost part of an otherwise circular outermost edge of an opening in said facing member and said facing member abutting on one end face of the roller.

References Cited in the file of this patent UNITED STATES PATENTS 43,294 Dalton June 28, 1864 2,071,941 Flaws Feb. 23, 1937 2,105,469 Bosch Jan. 18, 1938 2,954,940 Herrrnann Oct. 4, 1960 2,982,492 Spielman May 2, 1961 2,990,131 Carlsson June 27, 1961

Claims (1)

1. IN A MECHANISM FOR AUTOMATICALLY BLOCKING A ROLLER FOR A LIFTING BAND OF A VENETIAN BLIND, COMPRISING A LIFTING BAND, AT LEAST ONE FACING MEMBER, A ROLLER POSITIONED IN SAID FACING MEMBER AND HAVING A CIRCULAR RECESS IN ONE OF ITS ENDS, A FIXED STOP ON SAID FACING MEMBER, A BLOCKING MEMBER DISPLACEABLE INWARDLY BY SAID BAND WHEN WOUND ON SAID ROLLER AND IN OUTWARDLY RADIAL DIRECTION WITH RESPECT TO SAID ROLLER TO COOPERATE WITH SAID FIXED STOP WHEN THE BAND IS RELIEVED, AND SLIDABLY MOVABLE INTO BLOCKING POSITION SOLELY BY THE ACTION OF ITS OWN WEIGHT, SAID BLOCKING MEMBER BEING LOOSELY DISPOSED WITH A CERTAIN RADIAL CLEARANCE WITH RESPECT TO SAID ROLLER IN SAID RECESS AND POSITIONED BENEATH THE SURFACE OF SAID ROLLER FACE, SAID RECESS BEING SHAPED AS A CIRCULAR ARC AND BEING CONCENTRICAL WITH THE AXIS OF SAID ROLLER, AND LATERAL ARMS SHAPED AS CIRCULAR AXIS ON SAID BLOCKING MEMBER AND HAVING A PROJECTION GUIDED IN AN APERTURE IN THE ROLLER FACE, A STOP ON THE BLOCKING MEMBER PROTRUDING IN THE AXIAL DIRECTION OF THE ROLLER, SAID LAST MENTIONED STOP STRIKING AGAINST SAID FIXED STOP IN THE OUTERMOST POSTION OF THE BLOCKING MEMBER CLEAR OF THE SAME IN THE INNERMOST POSITION THEREOF.

Images