PATENT SPECIFICATION
`DRAWINGS ATTACHED
`
`Inventor :
`
`RONALD STEPHEN SKIDM ORE
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`1,] ”74,127
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`1.174,127
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`Date of filing Complete Specification (under Section 3 (3) of the Patents
`Act I949): 24 july, I968.
`
`Application Date: l9 july, I967.
`
`Application Date: 7 March,
`
`I 968.
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`Complete Specification Published: l0 Dec., I969.
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`No. 33058/67.
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`No. ll026/68.
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`Index at acceptance: —~El J(465, 466, 467)
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`International Classification: —E 06 b 9/305
`
`COMPLETE SPECIFICATION
`
`Venetian Blind
`
`We, J. AVERY & COMPANY (EST. 1834)
`LIMITED of Sunblind House, 82—90 Queens-
`land Road, London, N.7, a Company incor-
`porated under the Laws of the United King-
`dom of Great Britain and Northern Ireland,
`do hereby declare the invention for which
`we pray that a patent may be granted to us,
`and the method by which it is to be performed,
`to be particularly described in and by the
`following statement: —
`The invention relates to venetian blinds.
`In a venetian blind it is usual to have two
`completely independent drive mechanisms; one
`to raise and lower the slats of the blind and
`the other to tilt the blind. With the usual
`cord operated mechanisms this involves two
`independent
`sets of cords
`for each blind.
`These cords are insightly, particularly when
`the blind is in a raised position, and further-
`more there is a possibility that the two sets
`of cords may become entangled in each other.
`Alternatively,
`if
`the two sets of operating
`cords .are arranged at opposite ends of the
`blind, there are two unsightly regions of cord
`and it is not possible to control the raising/
`lowering and tilting of
`the blind from one
`location.
`
`A venetian blind in which the raising/
`lowering and tilting of the slats are carried
`out by a single cord has previously been
`proposed. In this proposal, a single operat-
`ing cord drives
`a
`substantial
`longitudinal
`shaft, which extends along the whole length
`of the head member, through either a worm
`gear or a bevel gear. The longitudinal shaft
`then drives
`tape
`lifting devices
`and tilt
`mechanisms at various locations immediately
`above the corresponding lifting cords and
`ladder web. An arrangement of
`this kind
`is cumbersome in operation, partly because
`the longitudinal shaft must have suflicient
`
`[Price 4:. 6d.]
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`the
`rigidity to avoid twisting of
`tortional
`shaft under the load of the blind. The cor-
`respondingly heavy shaft requires correspond-
`ingly substantial bearings which add to the
`cumbersome nature of the device as a whole.
`According to the invention there is provided
`a venetian blind including a drive mechanism
`to raise and lower the slats and bottom rail of
`the blind incorporating a series of
`lifting
`tapes or cords arranged to lift the slats and
`bottom rail at
`locations
`spaced out along
`the length of the blind, a lifting tapes or
`cords extending along the head member
`to
`a common winding location in the vicinity of
`the input to the drive mechanism, the blind
`also including a slat-tilt mechanism connected
`to the said drive mechanism and incorporating
`a slipping torque-limiting drive arrangement.
`By this means, with suitable drive ratios,
`small movements of the drive mechanism tilt
`the slats
`throughout
`their whole range of
`possible movement without
`substantially
`affecting the raised/lowered position of the
`blind and large movements of
`the drive
`mechanism to raise and lower the blind are
`possible without
`interference from the tilt
`mechanism, due to the slipping drive arrange—
`ment.
`
`is
`it
`In a venetian blind of this nature,
`possible to use a cord drive arrangement in
`the said drive mechanism and use this cord
`drive to raise and lower the blind and also to
`tilt
`the slats. Preferably such a cord drive
`is constituted by an endless cord coupled to
`a driving, pulley; this permits the cord drive
`to be particularly neat because there are no
`cord ends to be come entangled and a com-
`paratively short cord can be used as
`the
`amount of
`free cord does not
`increase or
`decrease with raising and lowering of
`the
`blind.
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`Norman Int. Exhibit 1004
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`Norman Int. Exhibit 1004
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`1,174,127
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`Preferably the drive mechanism includes a
`rotatable tape winding drum which is driven
`through a gear mechanism and around which
`lifting tapes or cords are wound or unwound
`to raise or lower the blind.
`Preferably slat
`tilt mechanism includes a
`rotatable shaft which extends along the upper
`edge of the blind and has mounted thereon
`a series of tilt drums over which are passed
`tilting tapes or cords of the slat-tilt mechan-
`ism. Operation of the drive mechanism thus
`rotates the tilt drums which in turn tends to
`move the tilt tapes or cords to adjust
`the
`angle of the slats. When the end of available
`tilting movement of the slats is reached, the
`tilt drums continue to rotate whilst the tilt—
`ing tapes or cords slip thereon.
`The rotatable shaft which extends along
`the upper edge of the blind is required to
`drive the slat
`tilt mechanism but not
`the
`lifting mechansm and ttis a very light shaft
`with a low torque capacity is quite suitable.
`An embodiment of the invention will now
`be described by way of example only with
`reference to the accompanying drawings,
`in
`which:—
`Figure 1 is a perspective view of a vene-
`tian blind,
`some parts being broken away
`for clarity and convenience,
`Figure 2 is a view of the raising and lower-
`ing mechanism of Figure 1 or Figure 4
`showing a detail on an enlarged scale;
`Figure 3 is a vertical section through part
`of the arrangement of Figure 1, on section
`line Ill—III of Figure 4 and,
`Figure 4 is section on the line IV—IV of
`Figure 3.
`The venetian blind incorporates a head
`member 11 of channel section sheet steel or
`other metal. The majority of
`the working
`components of the blind are enclosed within
`the head member to give a neat appearance.
`The gear box 12 (best seen in Figures 3
`and 4) has an input shaft 13 on which is
`mounted an input driving pulley 14. This
`pulley is in turn driven by an endless cord
`15. There is a torque limiting drive from the
`pulley 14 to the shaft 13. This drive is
`constituted by a dog clutch (not shown) with
`tapered dogs. When a low torque is being
`transmitted, a series of belville washers 10
`holds the tapered dogs in engagement with
`each other and thus maintains a drive be-
`tween the pulley 14 and shaft 13. On the
`other hand, one a predetermined torque is
`exceeded,
`the tapered dogs move out of en-
`gagement against
`the force of the bellville
`washers 10 and thus permit slipping between
`the pulley 14 and shaft 13.
`A tape winding drum 16 is driven from
`the shaft 13 through spur gears 17 and 18,
`shaft 19 and spur gears 21, 22 and 23
`spur gear 22 being free to rotate on shaft 13
`on a bearing 24. The whole of the gear box
`12,
`including the spur gears, shaft and side
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`members 20, are formed of nylon or other
`suitable plastics material. The winding drum
`16 and spur gear 23 are mounted for rota-
`tion together on a common shaft 25. The spur
`gears 17, 18, 21, 22 and 23 should in a typical
`case be such that the tape winding drum 16
`rotates at a slower
`rate than the driving
`pulley 14,
`the drive ratio being 6: 1. This
`drive ratio of 6:1 is
`suitable for heavy
`venetian blinds where it is desired to achieve
`a substantial mechanical advantage between
`the force required on the cord 15 and the force
`required to raise the blind. With smaller and
`lighter venetian blinds, a ratio of 4:1 or 1:1
`may be suitable.
`The tape winding drum 16 is mounted with—
`in a cage 26 which incorporates a series of
`apertured sheet members which divide the
`drum 16 into five sections each suitable for
`the winding of an individual
`tape.
`In the
`case shown in the drawing, the venetian blind
`is comparatively short and incorporates only
`two tapes 27 and 28. These tapes both pass
`under the gear box 12, being guided by cross
`members 31, 32 and 33 of the gear box,
`and the base of the head member 11 to posi—
`tions where they pass down through the base
`of the head member 11 to the bottom stick
`34 of the blind. The head member 11 incor—
`porates two cross members 35 and 36,
`the
`main purpose of which will be described
`hereinafter. If the blind is sufiiciently long
`to required more than two lifting tapes and
`ladder webs,
`there should be a correspond-
`ingly increased number of cross members such
`as 35 and 36 and of the other equipment
`associated with these cross members. The
`cross members each incorporate a spigot 37
`which engages in an aperture in the base of
`the head member 11 and these spigots in
`turn each incorporate an aperture 38. The
`tapes 27 and 28 pass down through the aper—
`tures 38. The two cross members 35 and 36
`are formed of nylon or a similar plastics
`material so that the edges of the apertures 38
`provide smooth guiding surfaces for the tapes.
`In operation of the raising and lowering
`mechanism, the cord 15 is operated to rotate
`the pulley 14. This in turn rotates the tap
`drum 16 as described above. Rotation of
`the tape drum 16 causes the tapes 27 and
`28 to be wound or unwound therefrom and
`this in turn causes the tapes 27 and 28 to
`raise or
`lower
`the bottom stick 34,
`thus
`raising or lowering the slats of the blind.
`When the blind slats are in a raised or part-
`ly raised condition,
`there is a tendency for
`the weight of the bottom rail 34 and slats 41
`to rotate the winding drum 16 and other
`components of the gear box due to tension
`in the tapes 27 and 28. In order to over—
`come this tendency a friction brake is pro-
`vided as shown in Figure 2. This bralze com-
`prises a nylon brake member 42 which passes
`over the pulley 14 in close proximity there-
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`Norman Int. Exhibit 1004
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`Norman Int. Exhibit 1004
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`1,174,127
`W...”
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`to. The brake member 42 is formed of a
`plastics material such as nylon and thus is
`slightly flexible. It is mounted at one end by
`a screw 43 to the head member 11. At the
`other end, a screw 44 in the head member
`provides adjustment for the brake member
`42 and enables it to engage with a desired
`pressure on the driving cord 15, where this
`cord passes over the pulley. 14. In this way, the
`functional resistance to rotation of the pulley
`is adjustable by means of the screw 44. The
`adjustment
`should be such that no undue
`force is
`required to operate the cord 15
`but sufficient
`to prevent
`the weight of the
`bottom stick 44 and slats 41 from lowering
`the blind from its raised position. Due to
`the fact
`that
`the friction brake is arranged
`on the input side of the reduction gearing, a
`very small frictional force is sufficient to pre-
`vent
`the blind from falling under
`its own
`weight
`from a raised position. This small
`frictional force assists the smooth operation
`of the blind as a whole.
`Figure 2 also shows that the cord 15 passes
`down through a slot in the base of the head
`member inside a nylon or similar guide mem-
`ber 45 which prevents the cord 15 from rub—
`bing against the edge of the slot in the base
`of
`the head member. The brake members
`42 also tends to prevent
`the cord 15 from
`coming off the pulley 14.
`a
`The
`slat—tilt mechanism incorporates
`rectangular
`longitudinal shaft 51 which is
`driven from the shaft 13 by means of spur
`gears 17 and 18, shaft 19 spur gears 21 and
`52, shaft 53 and bevel gears 54 and 55. Each
`cross member such as 35 is generally in the
`form of a rectangular box 56 which is sup-
`ported against the sides of the head member
`11 by means of extensions 57 and 58. The
`spigot 37 engaging in an aperture in the
`base of the head member 11 also assists loca-
`tion of the cross member. The top of the
`rectangular box 56 is open and the sides
`thereof are slotted at 59 in order to receive
`a nylon or similar tilt drum 61 on an integral
`stub shaft 62. The stub shaft 62 engages
`with the base of the slots 59 which provide
`a bearing to rotatably support the tilt drum
`61 in the cross member 35. The stub shaft
`62 has a rectangular aperture through which
`the rectangular shaft 51 passes, thereby pro-
`viding a driving connection so that the tilt
`drum 61— is rotated by rotation of the drive
`pulley 14.
`The cords of a typical ladder web 60 pass
`over the tilt drum 61 and through apertures
`64 in the base of the head member 11. The
`surface of the tilt drum 61 incorporates ridges
`such as 61a which provide a moderate grip
`between the cords 63 and the drum 61. Thus,
`rotation of the tilt drum 61,
`in one direc-
`tion or the other by means of the cord 15
`and the interposed driving connection,
`thus
`causes cord 63 to be raised at one side and
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`lowered at the other side in order to tilt the
`slats 41 in the usual way.
`Although only one tilt drum 61 has been
`described in detail
`there is a corresponding
`tilt drum 65 near the other end of the head
`member 11 and this is also driven by the
`shaft 51. If no further cross members are
`provided there will also be further tilt drums.
`The shaft 51 is located axially by means of a
`collar 66.
`
`The gear ratios within the gear box 12 are
`such that only small
`lengths of lifting tapes
`27 and 28 are paid out from or wound onto
`the drum 16 during the complete range of
`tilting movement of
`the slats 41. Thus,
`in
`order to raise or lower the blind, a slipping
`torque-limiting drive
`is
`required between
`the gear box and the cords 63 of the ladder
`web. This slipping drive is provided by a tilt
`drum 61 and the cords 63 in that the drum 61
`can continue to rotate whilst
`the cords 63
`remain stationary.
`large movements of
`Thus,
`in operation,
`the cord 15 are used to raise and lower the
`blind as a whole whilst slip takes place be-
`tween the tilt drurns 61 and 65 and their asso—
`ciated ladder web cords.
`The length of the lifting tapes 27 and 28 is
`made such that when the blind is
`fully
`lowered, the lifting tapes become slack, leav-
`ing the slats 41 and bottom rail 34 suspended
`by the ladder webs 60. There is sufficient
`slack in the tapes 27 and 28 to permit some
`movement of the cord 15 without any rais-
`ing or
`lowering motion taking place. This
`small range of movement of the cord 15 is
`used to tilt the slats 41 and the bottom rail
`34 to the desired angular position. It should
`be noted that as soon as the tapes 27 and
`28 come under tension and thus take the load
`of the bottom stick 34 off the ladder web 60,
`there is a very much reduced pressure be—
`tween the tilt drums 61 and 65 and the cord
`63 of the ladder web due to the reduced ten-
`sion in the cord 63. This further reduces
`the friction between the tilt drums 61 and
`65 and the cord 63 during the major part of
`3 raising or lowering operation.
`When the blind is to be raised from its
`lowermost position, either side of the cord 15
`may be pulled. Either direction of rotation
`will result
`in winding of
`the lifting tapes
`around the tape drum, thus raising the blind.
`Depending on which side of the cord 15 is
`pulled the lifting tapes will be wound in
`one direction or the other. Due to this feature,
`it
`is not possible to overload the lifting
`mechanism by pulling too hard on the ‘wrong’
`side of the cord and thus no positive stop is
`needed to prevent such an overload.
`When it is desired to lower the blind from
`a fully raised position, a pull on the ‘wrong’
`side of the cord 15 tends to build up exces-
`sive forces in the lifting mechanism, particu-
`larly excessive tension in the lifting cords.
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`Norman Int. Exhibit 1004
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`Norman Int. Exhibit 1004
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`1,174,127
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`—_____.——-————
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`2. A venetian blind as claimed in claim 1 in
`which a cord drive arrangement is used to
`operate the drive mechanism.
`3. A venetian blind as claimed in claim 2
`in which the cord drive arrangement is con-
`stituted by an endless cord coupled to a driv-
`ing pulley.
`4. A venetian blind as claimed in claim 3
`including a friction brake operative on the
`cord where it passes over the pulley.
`5. A venetian blind as claimed in claim
`2 or claim 3 or claim 4, in which the drive
`mechanism includes a rotatable drum which
`is driven through a gear mechanism and
`around which lifting tapes or cords are wound
`or unwound to raise or lower the blind.
`6. A venetian blind as claimed in claim
`5 in which the gear mechanism incorporates
`spur reduction gearing.
`7. A venetian blind as claimed in any of
`the preceding claims
`in which the drive
`mechanism drives a rotatable shaft which
`extends along the upper edge of the blind and
`has mounted thereon a series of tilt drums
`over which are passed tilting tapes or cords
`of the slat-tilt mechanism.
`8. A venetian blind as claimed in claim 7
`in which the drive mechanism to raise and
`lower the slats is such that there is lost motion
`in the drive mechanism when the blind is
`fully lowered so that the tilt angle of
`the
`slats is adjustable without any raising/lower-
`ing of the blind.
`9. A venetian blind as claimed in claim
`8 in which the lost motion is provided by
`causing lifting tapes or cords to become slack
`with the blind fully lowered, the slats and a
`bottom stick being supported on tilting tapes
`or cords.
`10. A venetian blind as claimed in any
`of the preceding claims including a further
`torque limiting drive in the drive mechanism
`to prevent over-loading of the drive mechan—
`ism by an excessive operating force in a
`direction to raise the blind further when it
`is already in the fully raised position.
`11. A venetian blind as claimed in claim
`10 wherein the lifting tape or cord winding
`arrangement is such that from the lowermost
`position of the blind, operation of the drive
`mechanism and the winding arrangement in
`either direction causes the lifting tapes or
`cords to raise the blind.
`12. A venetian blind substantially as des-
`cribed with reference to and as shown in
`the accompanying drawmgs.
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`the torque limiting drive between
`However,
`the pulley 14 and shaft 13 prevents an
`excessive force from being applied to the
`lifting mechanism.
`If the ‘wrong’
`tape is
`pulled with the blind in its fully raised posi-
`tion,
`the tapered dog teeth of
`the torque
`limiting drive slip over each other, at the same
`time generating a substantial noise. This noise
`provides a warning to the operator that the
`wrong side of the cord 15 is being pulled.
`In this way, the torque limiting drive avoids
`the requirement for a positive stop in the
`uppermost position of the blind.
`The use of a series of spur gears in the gear
`box has the advantage that simply by chang-
`ing a small number of cogs. It is possible to
`vary the gear
`ratio to meet
`the require-
`ments of a particular blind. A further advan-
`tage of spur gearing is that even with simple
`nylon gears formed by injection moulding, a
`gear box of high mechanical efficiency can
`be provided. This feature, in conjunction with
`the very light force required on the friction
`brake and the free rotation of the compara-
`tively light
`longitudinal shaft 51 results in
`a blind which requires a very low operating
`effort. As a result of
`this, a suitable gear
`ratio can be chosen so that even a large blind
`can be raised by a force of: less than 10 lbs,
`without
`requiring an excessive amount of
`pulling on the cord 15.
`A further advantage of the arrangement
`whereby all the lifting tapes are wound on a
`single winding drum in the vicinity of the gear
`box is that the reduction in the cost of the
`blind due to the simplified longitudinal shaft
`and simplified arrangement in the vicinity of
`the upper end of the lifting tapes and ladder
`webs more than offsets the cost of the single
`tape winding drum and the drive thereto.
`To summarize the operation of the blind
`by a user thereof, large movements of the cord
`15 cause the blind as a whole to be raised or
`lowered whereas small movements of the cord
`15, particularly with the blind fully lowered,
`cause the slats to be tilted. Thus there is pro-
`vided a blind which is simple to operate and
`which incorporates only a single endless loop
`operating cord.
`WHAT WE CLAIM IS:—
`1. A venetian blind including a drive
`mechanism to raise and lower the slats and
`bottom rail of the blind and incorporating a
`series of
`lifting tapes or cords arranged to
`lift
`the slats and bottom rail at
`locations
`spaced out along the length of the blind, the
`lifting tapes or cords extending along the
`BROOKES, MARTIN & WILSON,
`head member to a common winding location in
`Chartered Patent Agents.
`the vicinity of the input to the drive mechan-
`Phoenix Chambers,
`ism,
`the blind also including a slat—tilt
`84 Colmore Row,
`mechanism connected
`to the
`said
`drive
`Birmingham. 3.
`mechanism and
`incorporating
`a
`slipping
`Agent for Applicants.
`____________._~—-—s~——--—v-—-—-
`torque-limiting drive arrangement.
`Leamington Spa, 1969.
`onery Ofiice by the Courier Press,
`Printed for Her Majesty’s Stati
`W.C.Z, from which copies may be obtained.
`25, Southampton Buildings, London,
`Published by the Patent Ofice,
`
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`Norman Int. Exhibit 1004
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`Norman Int. Exhibit 1004
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`1174127
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`COMPLETE SPECIFICATION
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`‘9
`2 SHEET”
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`Thls drawing Is a reproduction of
`the Original on a reduced scale
`Sheet 1
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`Norman Int. Exhibit 1004
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`Norman Int. Exhibit 1004
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`1174127
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`COMPLETE SPECIFICATION
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`2
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`SHEETS
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`This drawing Is a reproduction of
`the Original on a reduced scaIe
`Sheet 2
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`Norman Int. Exhibit 1004
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`Norman Int. Exhibit 1004
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