Note: Descriptions are shown in the official language in which they were submitted.
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MANUALLY OPERATABLE ELECTRIC CURTAIN
BACKGROU~D OF THE INVENTION
The present invention relates to a laterally
drawn blind such as a curtain assembly and a folding
partition, and more particularly, to a curtain which is
automatically actuated by an electric motor and easily
drawn by hand while the motor is not activated.
It is known that an electric curtain assembly is
provided with an electromagnetic clutch between an
electric motor and a cord pulley. The electromagnetic
clutch joins the cord pulley with the motor when an open
or close switch is pushed to rotate the motor in a
manner that the cord pulley pulls a cord to open or
close the curtain cloth, The electromagnetic clutch
disjoins the cord pulley from the motor when a stop
switch or limit switch is activated, so that the curtain
is easily opened or closed by hand without receiving the
frictional resistance of the motor.
However, the known curtain assembly is not
largely used. One reason is that the electromagnetic
clutch inconveniently requires a periodical maintenance.
It is not easy for most families to inspect and maintain
the electromagnetic clutch in the curtain assembly.
~ Furthermore, an extra energy is consumed to energize the
;~ electromagnetic clutch while the motor runs. Another
disadvantage is that the known curtain assembly is
somewhat expensive due to the electromagnetic clutch.
SUMMARY OF THE INVENTION
The primary object of the invention, therefore,
is to provide a manually and automatically operatable
electric curtain of the type having no electromagnetic
clutch.
Another object of the invention is to provide a
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manually and automatically operatable electric curtain
that requires no periodical maintenance.
Still another object of the invention is to
produce a manually and automatically operatable electric
curtain at low cost.
A further object of the invention is to provide
a manually and automatically operatable electric curtain
by which no extra electric energy is consumed.
These objects are achieved in the present
invention by the use of an electric circuit having a
motor-reversing means and a planetary gearing between a
motor and a cord pulley and an electric circuit for
operating the motor. The gearing comprises a sun gear
fixed to the output axis of the motor, an arm rotatably
fitted on the output axis, a planet gear rotatably
mounted on the arm to engage the sun gear, a driven gear
fixed to the cord pulley for selective engagement with
the planet gear. The cord pulley is hanged by a curtain
cord to to draw a curtain cloth. It is arranged that the
rotational resistance of the planet gear round its own
axis is larger than the rotational resistance of the arm
round the sun gear or the output axis of the motor. This
means that the planet gear is more easily rotatable
round the output axis than round its own axis. The
electric circuit comprises main and auxiliary
motor-driving circuits and open, close and stop
switches. The electric circuit may have either or both
limit switches, if necessary.
When the open or close switch is activated, the
main motor-driying circuit rotates the motor in either
of the both rotational directions. As the motor rotates,
the planet gear turns together with the arm round the
output axis of the motor until it engages the driven
gear to prohibit the rotation of t,he arm. Then, the
planet gear rotates round its own axis and transmit the
rotation of the sun,gear or the motor to the driven
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gear. The driven gear or the cord pulley draws the
curtain cord to open or close the curtain.
Meanwhile, once a stop switch or limit switch is
activated, the main motor-driving circuit interrupts the
S supply of electric current. But, in response to a signal
to stop the motor, the auxiliary motor-driving circuit
supplies an inverse electric current to the motor for a
predetermined short time, so that the motor is instantly
reversed before it stops. When the motor reverses, the
planet gear is caused to disengage from the driven gear
and let the driven gear to be free from the motor during
the stoppage of the motor. Thus, the curtain is easily
drawn by hand without receiving the rotational
resistance of the motor.
One important feature of the present invention
is that the cord pulley is separated from the motor not
by an electromagnetic clutch but by the planetary
gearing, which is more inexpensive than the
electromagnetic clutch. The electric circuit has main
and auxiliary motor-driving circuits of which the
elements are very inexpensive and are already available
on the market. The planetary gearing is simple and needs
no periodical maintenance. Besides, the electric curtain
consumes no extra electric energy to energize and heat
the electromagnetic clutch.
The foregoing and other objects and advantages
of the present invention will be better understood by
reference to the following disclosure and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. l is a perspective, partly broken view of
the relevant portion of the curtain assembly according
to the present invention;
FIG. 2 is a front view of the gearing
transmission of FIG. 1, illustrating the planet gear to
engage the driven gear on one side thereof when an open
switch is activated;
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FIG. 3 is a view similar to FIG. 2, illustrating
the planet gear disengaged from the driven gear when a
stop switch is activated;
FIG. 4 is a view similar to FIG. 2, illustrating
S the planet gear to engage the driven gear on the other
side when a close switch is activated; and
FIG. 5 is a schematic diagram of an electric
circuit utilized with the curtain assembly of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As seen in FIG. 1, an electric motor 10 is
equipped with a reduction gearing 12. A sun gear 20 is
fixed to the output axis 14 of the motor 10. The motor
10 is mounted in the box 11, which is fixed to the
curtain rail or other fixed portion. An arm 25 is
rotatably fitted on the output axis 14. A planet gear 30
is rotatably mounted on the arm 25 and engaged with the
sun gear 20. A cord pulley 42 is rotatably mounted on
the box 11 abovè the motor 10. A driven gear 40 is
coaxially fixed to the cord pulley 42. The axes of the
driven gear 40 and the sun gear 20 are in a common
vertical plane. The half distance between the axes of
the sun gear 20 and the driven gear 40 is less than the
distance between the axes of the sun gear 20 and the
planet gear 30, so that the planet gear 30 engages the
driven gear 40 on one side when the sun gear 20 rotates
in one direction and on the other side when the sun gear
20 rotates in the other direction.
A curtain cord 44 loops through a pair of
vertical guide pulleys 46 provided on one end of a
curtain rail 45 between the cord pulley 42 and a
horizontal tension pulley 48 mounted on the other end of
the rail. A multiplicity of runners 47 are movably
mounted in the rail 45 to suspend a curtain cloth 50.
The leading runner 47a is attached to the cord 44, so
that the curtain cloth is opened when the cord 44 is
drawn in one direction and closed when the cord 44 is
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drawn in the other direction. A switch box 13 is
provided with open, close, and stop button switches O,
C, and S.
As seen in FIG. 5, the electric circuit has a
main motor-driving circuit Dl, an auxiliary
motor-driving circuit D2, a pulse-generating circuit PG,
a detecting circuit D3, and open, close and stop button
switches O, C, and S. When the open switch O is
activated, the main motor-driving circuit Dl supplies an
electric current to the capacitor motor 10 in a manner
that the motor rotates in one direction in which the
curtain is opened. When the close switch C is activated,
the main motor-driving circuit Dl rotates the motor in
the other direction in which the curtain is closed. When
the stop switch S is activated, the main motor-driving
circuit Dl interrupts the supply of electric current. On
the other hand, when the stop button switch is pushed,
the pulse-generating circuit PG is activated to output
pulses to the auxiliary motor-driving circuit D2 for a
short time, which can be predetermined by a capacitor
built in the pulse-generating circuit. While the
auxiliary motor-driving circuit D2 receives the pulses
from the pulse-generating circuit PG, it supplies an
inverse electric current to the motor 10 in a manner
that the motor is instantly rotated in the direction
opposite to the previous direction in which the motor
has been rotated by the main motor-driving circuit.
As seen in FIG. 2, when the open switch is
pushed, the motor 10 rotates with the sun gear 20. The
frictional resistance against the rotation of the arm 25
is less than that against the rotation of the planet
gear 30 about its own axis, so that the planet gear 30
is prevented from rotation about its own axis but
allowed to turn about the sun gear 20 together the arm
25, as indicated by the arrow A. When the planet gear 30
is moved in a position illustrated by an imaginal line,
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it engages the driven gear 40 and limits the rotation of
the arm 25. Then, the planet gear 30 starts to rotate
about its own axis and causes the driven gear 40 to
rotate, so that the cord 44 runs to open the curtain
cloth. Thereafter, the stop button switch is pushed
before or when the curtain cloth is full opened.
As seen in FIG. 3, when the stop button switch
is pushed, the auxiliary motor-driving circuit rotates
the motor 10 in the direction indicated by the arrow B
for an instant, resulting in that the planet gear 30 is
disengaged from the driven gear 40.
As seen in FIG. 4, when the close button switch
is pushed, the motor 10 rotates the planet gear 30 round
the sun gear 20 in the direction indicated by the arrow
B to engage the driven gear 40, so that the driven gear
40 rotates in the direction opposite to the previous
direction when the open switch is pushed. Then, the
curtain cloth starts to close When the stop button
switch i8 pushed before or when the curtain cloth is
full closed, the motor can not stop without rotating in
the direction indicàted by the arrow A for a very short
time. This results to that the planet gear 30 is
disengaged from the driven gear 40 as illustrated by an
imaginal line of FIG. 4. While the motor 10 stops, the
rotational transmission between the motor 10 and the
driven gear 40 is always interrupted with the result
that the driven gear 40 is easily rotatable by hand to
close or open the curtain cloth.
The electric circuit as illustrated in FIG. 5
; 30 allows the motor 10 to reversely rotate for an instant
immediately before it stops. The motor 10 is arranged to
stop whenever it receives a resistance beyond a
predétermined torque. This permits to eliminate open and
close limit switches, because the motor 10 automatically
stops when the curtain is full opened, full cloi~ed or
prevented from moving by accident. The stoppage of the
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motor 10 is detected by a detecting circuit D3 using a
hall device IC as a sensing element. The motor 10 of a
capacitor type is operated by the main circuit D1 for an
ordinary time from when the open button switch O or
close button switch C is pushed to when the stop button
switch S or the detecting circuit is actuated and by the
auxiliary circuit D2 for a predetermined short time
since the stop button switch S or the detecting circuit
D3 is activated. The main circuit D1 includes a pair of
flip-flop elements F1 to memorize each operation of the
open switch O and the close switch C and a solid state
relay element SSR1, which supplies current to the motor
10 in a manner that the motor 10 rotates in the
direction in which the curtain is opened when the open
switch O is activated and in the opposite direction in
which the curtain is closed when the close switch C is
activated. When the stop switch S is pushed or the
detecting circuit D3 detects the stoppage of the motor
10, the flip-flop element F1 is reset to stop the motor
10. The auxiliary circuit is also provided with another
pair of flip-flop elements F2 to memorize each
activation of the open and close switches O and C and
another solid state relay SSR2 to rotate the motor 10 in
the opposite direction. The solid state relay SSR2 in
the auxiliary circuit D2 is active only while a
pulse-generating circuit PG is producing pulses. The
pulse-generating circuit includes one-shot
multi-vibrator MV, which generates and transmits pulses
to the auxiliary circuit D2 for a predetermined small
period in which the solid state relay SSR2 is activated.
The electric circuit of FIG. 5, requiring no
mechanical means nor limit switch, makes the motor 10 to
instantly reverse the rotational direction thereof prior
to being stopped, so that the engagement between the
planet géar 30 and the driven gear 40 is taken off as
seen in FIG. 3. Therefore, the curtain cloth is easily
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opened or closed by hand while the motor stops. If
another type of motor were used, the open and close
limit switches Ll and L2 would be provided as
illustrated by imaginal lines in FIG. 1. The limit
switch would actuate in the same way as the stop switch.
The inventive device is not limited the curtain
assembly which is illustrated in the accompanying
drawings but available for folding doors or the like
which is laterally opened or closed.
The planetary gearing, as an transmission
between the motor and the cord pulley, is simple,
inexpensive, and easy to be maintained in comparison
with the conventional electromagnetic clutch. The all
electric elements as shown in FIG. 5 are also
inexpensive and already available on the market.
While the preferred embodiment of the invention
has been shown and described it should be understood
that the present invention should not be limited thereto
but that the invention is intended to embrace all
embodiments coming within the scope of the appended
claims.
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