Note: Descriptions are shown in the official language in which they were submitted.
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Docket # 45,970
CASSETTE BLIND WITH BRAKE COUPLING
FIELD OF THE INVENTION
The present invention pertains to a cassette blind with a winding
shaft that is connected by coupling elements to a stationary pin and to a
S drive member, where the coupling elements to the drive member engage
in a winding up direction of the blind, and the coupling element connected
to the stationary pin engage in an unwinding direction of the blind. In
particular the present invention relates to such a blind where the winding
shaft is prevented from unrolling at the end of the winding up.
BACKGROUND OF THE INVENTION
A cassette blind is known from DE 42 39 507-A1 and the
corresponding U.S. Patent 5,443,109. This document describes friction
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disks, which are alternately fixed with teeth in axial grooves on the outer
circumference of a stationarily anchored pin and in axial grooves on the
inner circumference of a tubular housing which can be coupled with the
drive member in the direction of rotation, and which can be pressed against
5 each other by axial forces with an axial displacement. To achieve this, one
of two end disks which are axially displaceable on the pin are tensioned by
a torque spring in the direction of rotation within a predetermined angle
of rotation, and the other end disk is only axially displaceable. Relatively
strong coupling or braking forces are initiated due to the relatively weak
10 torque spring, so that such a drive runs smoothly and is especially suitable
for high blind weights. The problem arises in such and similar cassette
blinds that even though the weighting profile arranged at the lower edge
of the set of blinds can be pulled against the cassette profile of the cassette
accommodating the winding shaft and the blind wound up on it when the
15 blinds are being pulled up, it drops back somewhat after the driving forces
are eliminated, so that a narrow strip of the set of blinds again becomes
visible between the weighting profile and the cassette profile. This is
frequently undesirable, because it compromises the appearance of the
pulled-up cassette-type blind.
SUMMARY AND OBJECTS OF THE INVENTION
The object of the present invention is therefore to design the drive
means of the blind such that the weighting profile no longer drops back
after the blind has been pulled up.
The present invention includes a winding shaft which is connected
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to a stationary pin by a pin coupling means, and to a drive member by a
drive coupling means. The drive coupling means engages the drive
member to the winding shaft during rotary movement of the drive means
in a winding up direction, and the pin coupling means engages the winding
5 shaft to the stationary pin during an unwinding direction. The coupling
elements are arranged on the winding shaft rotatably over a predetermined
angle against the action of the spring in the winding-up direction of the
blinds.
It is achieved due to this design that the drive member can still be
10 rotated further additionally by a predetermined angle against the action of
the spring at the end of the winding-up movement, when the weighting
profile has already come into contact with the cassette profile. When the
driving force applied manually or by a motor ceases to act, the weighting
profile is held by the force of the spring against the cassette profile, so that
15 the elements of the now active brake coupling are movable within the
predetermined angle of rotation for mutual engagement. The spring
counteracts the weight of the blinds and can be designed as a relatively
weak spring, so that the weight of the blinds pulls the coupling elements
attached to the winding shaft into one stop position. The spring comes into
20 action only at the end of the winding-up movement of the blinds, so that
it pulls the coupling elements into the other stop position of the
predetermined angle of rotation, so that the coupling elements are
rotatable in relation to one another within the predetermined angle when
the weighting profile is already in contact with the cassette profile.
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The angle of rotation of the winding shaft in relation to the coupling
elements associated with it, is greater than the switching angle necessary for
the engagement of the coupling elements acting between the winding shaft
and the pin. Preferably the coupling elements include inner and outer
S sleeves which are mounted concentrically one inside the other and are
rotatable with respect to one another. These inner and outer sleeves are
tensioned by the torsion spring against the direction of rotation of the drive
member during the winding-up of the blinds. The inner and outer sleeves
are provided on the winding shaft. The outer sleeve is non-rotatably
10 connected to the winding shaft, and the inner sleeve is connected rotatably
between stops to the driving member. Coupling elements between the pin
and the winding shaft include first and second brake disks which are
alternating connected non-rotatably to the pin and to the winding shaft.
A cam means axially biases the first and second sets of brake disks against
15 each other.
The various features of novelty which characterize the invention are
pointed out with particularity in the claims annexed to and forming a part
of this disclosure. For a better understanding of the invention, its
operating advantages and specific objects attained by its uses, reference is
20 made to the accompanying drawings and descriptive matter in which
preferred embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Figure 1 is a perspective view of a cassette blind,
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.
Figure 2 is a cross section through the cassette profile of the pulled-
up blinds,
Figure 3 is a cross section corresponding to Figure 2 according to a
design according to the state of the art,
Figure 4 is a longitudinal section through the drive-side end of the
winding shaft in an axial plane,
Figure S is a cross section along line V-V in Figure 4, and
Figure 6 is a cross section along line VI-VI in Figure 4.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENT
Referring to the drawings and in particular to Figure 1, the
exemplary embodiment shows a cassette blind, in which a set of blinds 1
includes a weighting profile 2 attached to the lower edge of which. The
blind 1 can be wound up within a cassette profile 3 on a winding shaft 4
15 mounted therein.
Most often drive members are used which are arranged on one end
within the winding shaft 4 and are actuated by a drive chain 5 led out of
the cassette profile 3 on the side next to the blinds 1, are used for this
purpose. It is also possible to have a motor-type drive means Cassette
20 blinds according to the present invention differ from roller blinds in that
the blinds 1 are wound up on the winding shaft 4 by driving forces rather
than by a torsion spring tensioned during the pulling down of the blinds.
The present invention includes a drive member 6 which can be
rotated by the drive chain 5. On the one hand, coupling members, which
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make possible a non-rotatable connection between the drive member 6 and
the winding shaft 4 for pulling up the blinds 1, are provided between the
drive member 6 and the winding shaft 4. On the other hand, braking
members, by which the winding shaft 4 is stopped as soon as driving forces
S in the direction of winding up cease to act on the drive member 6, are
provided between the winding shaft 4 and a stationarily anchored pin 7.
In the exemplary embodiment, the drive member 6 is mounted
movably concentrically within a tubular housing 8, with its angle of rotation
limited by stops. The angle of rotation is limited by stops 9 on the inner
10 jacket of the tubular winding shaft 4 and by stops 10 on the outer jacket of
the housing 8. Brake disks 11 and 12, which are alternately connected non-
rotatably to the pin 7 and non-rotatably to the tubular housing 8, are
arranged axially displaceably on the pin 7. The assembly consisting of the
brake disks 11 and 12 is supported at one end by an abutment 13 arranged
15 rigidly on the pin 7. The end disk 14 at the opposite end has an axial cam,
which cooperates with an axial cam at an intermediate member 15 such
that the assembly consisting of the brake disks 11 and 12 is released during
a rotary movement of the drive member 6 in the winding-up direction of
the blinds 1 and compressed by the axial cams at the beginning of a rotary
20 movement in the opposite direction.
A coupling member 16, which is non-rotatably connected to the
housing 8, is connected movably over an angle of rotation against a torsion
spring 17 to a sleeve 18, which is connected to the winding shaft 4 axially
movably but non-rotatably. The outer sleeve 18 is non-rotatably connected
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to the said winding shaft 4, and the inner sleeve 16 is connected rotatably
between stops to the drive member 6.
Pin-like radial projections of the sleeve 18 engage profiled grooves
of the stops 9 on the inner circumference of the tubular winding shaft 4.
S One end of the torsion spring 17 is attached to the coupling element 16,
and the other end of the torsion spring 17 is attached to the sleeve 18. The
torsion spring 17 is tensioned during a rotary movement of the drive
member 6 in the winding-up direction of the blinds 1.
The weight of the blinds overcomes the maximum spring tension, so
10 that the tubular housing 8 and the tubular winding shaft 4 reach a stop
position defined by the stops 9 and 10. The torsion spring 17 begins to act
at the top end of the rolling-up movement of the blinds 1 such that it
rotates the winding shaft 4 in a leading manner, so that the drive member
6 is still able to rotate further when the weighting strip has already
15 occupied the position shown in Figure 2 and is in contact with the cassette
profile 3, as a result of which the further rotary movement of the winding
shaft 4 is blocked. To avoid overstretching of the torsion spring 17, the
possibility of further rotation ls limited by the stops 9 and 10 between the
winding shaft 4 and the housing 8. In order for the assembly consisting of
20 the brake disks 11 and 12 to exert its braking effect, a slight backward
rotation of the drive member 6 is possible. This rotation now takes place
within the spring tension, so that the weighting profile 2 cannot drop back
into the undesired position shown in Figure 3. The value of the angle
limited by the stops 9 and 10 should be greater than the angle of rotation
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necessary for the engagement of the braking elements, so that the
weighting profile 2 is held against the cassette profile 3 in the position
shown in Figure 2 with a slight spring tension. The coupling element 16
non-rotatably connected to the tubular housing 8 is also designed in the
5 exemplary embodiment as a sleeve, on which the sleeve 18 is arranged
concentrically.
The application of the features of the present invention is not
limited to cassette blinds, but these features may also be applied to blinds
with a drive member that can be actuated whenever the resting position of
10 the blinds after actuation of the blind is to be reached at an exactly
predetermined point, e.g., in order to avoid or achieve the coverage of
slots, or to make it possible to represent special images with the blinds.
While specific embodiments of the invention have been shown and
described in detail to illustrate the application of the principles of the
15 invention, it will be understood that the invention may be embodied
otherwise without departing from such principles.
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LIST OF REFERENCE NUMBERS:
Blinds 10 Stop
2 Weightingprofile 11 Brake disk
3 Cassette profile 12 Brake disk
4 Winding shaft 13 End disk
Drive chain 14 End disk
6 Drive member 15 Intermediate member
7 Pin 16 Coupling element
8 Housing 17 Torsion spring
9 Stop 18 Sleeve
