U.S. patent number 3,914,645 [Application Number 05/487,918] was granted by the patent office on 1975-10-21 for multiple lamp unit for protection.
This patent grant is currently assigned to Educational & Commercial Avcom Inc.. Invention is credited to Kenneth Li Donnici.
United States Patent |
3,914,645 |
Li Donnici |
October 21, 1975 |
Multiple lamp unit for protection
Abstract
A multiple lamp unit suitable for use with a photographic film
projector which includes a plurality of lamps mounted on a
turntable which transports the lamps successively into a working
position. The turntable is incremented by means of an escapement
which stops it as each successive lamp is brought into the working
position. A photocell senses when the lamp in the working position
burns out and causes the escapement to increment the turntable. The
energy for rotating the turntable is provided by a torsion spring
which is wound by the operator as he replaces burned out lamps and
then unwinds to supply the rotational energy to increment the
turntable.
Inventors: |
Li Donnici; Kenneth (Brooklyn,
NY) |
Assignee: |
Educational & Commercial Avcom
Inc. (Malverne, NY)
|
Family
ID: |
23937649 |
Appl.
No.: |
05/487,918 |
Filed: |
July 12, 1974 |
Current U.S.
Class: |
315/89; 315/136;
353/85; 315/93; 315/313; 353/119 |
Current CPC
Class: |
G03B
21/2013 (20130101); G03B 21/2053 (20130101) |
Current International
Class: |
G03B
21/20 (20060101); H05B 037/04 (); H05B
039/10 () |
Field of
Search: |
;315/88,89,93,136,313
;240/37.1 ;352/198 ;353/85,87,119 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: La Roche; E. R.
Claims
What is claimed is:
1. In a projector for projecting visual images recorded on film a
multiple lamp unit for supporting and energizing a lamp in a
working position and for automatically transporting a fresh lamp
into said working position after the lamp in said working position
burns out comprising:
a plurality of lamps
a support member movably mounted for supporting said plurality of
lamps and for serially moving said lamps through said working
position;
motive means for moving said support member in a first
direction;
electrically powered escapement means for holding said member with
one of said lamps in said working position and for selectively
incrementing said support member in two stages first through a
major portion of the distance between adjacent lamps and then
through the remaining minor portion of said distance to bring said
successive lamps into said working position, said escapement means
requiring for operation at least a predetermined minimum level of
electrical power supplied thereto;
means for energizing said lamp in said working position;
common means for supplying electrical power both to the lamp in
said working position and to said escapement means;
means sensitive to the failure of the lamp in said working position
for initiating the action of said escapement means to increment
said support member including first delay means for preventing the
actuation of said escapement means during a gradual reduction in
the level of electrical power supplied by said common means when
the projector is operating in a fade out mode until said level is
below that necessary to operate said escapement means and second
delay means for preventing the incrementing of said support member
through said remaining minor portion until a predetermined time
after the incrementing through said major portion; and
means for removing power from said lamps during at least said major
portion of the incrementing of said lamps.
2. The multiple lamp unit of claim 1 wherein said support member
includes a rotably mounted turntable, said lamps being mounted on
said turntable at equal distances form the center thereof, said
escapement means including:
first and second pawls;
a common pivot for said pawls;
a plurality of ratchet teetn in the periphery of said turntable
equal in number to said plurality of lamps, said turntable being
normally held with a lamp in said wording position by the
engagement of the first pawl with one of said rachet teeth;
solenoid means actuated in response to said means sensitive to the
failure of a lamp for temporarily disengaging said first pawl from
said turntable for allowing said turntable to rotate, said second
pawl being biased toward said turntable for engaging one of said
ratchet teeth after the disengagement of said first pawl for
stopping the rotation of said turntable before the next lamp is
brought into said working position;
means for biasing said first pawl into engagement with said
turntable; and
means integral with said first pawl for disengaging said second
pawl from said turntable when said solenoid means is deactuated to
allow said first pawl to return under bias into engagement with
said turntable.
3. The multiple lamp unit of claim 1 wherein said means for
removing power includes a switch actuated by said escapement means
during the incrementing of said lamps.
4. The combination of claim 1 further including a projector having
a lens attached to the multiple lamp unit and means for giving
access to said lamps for replacing burned out ones thereof, said
access means being positioned on the side of said unit opposite
said lens.
5. The multiple lamp unit of claim 1 wherein said support member
includes a rotatably mounted turntable said lamps being mounted
about said turntable equidistantly form the center thereof.
6. The multiple lamp unit of claim 5 wherein said turntable
includes a plurality of ratchet teeth in the periphery for
cooperating with said escapement means each of said lamps being
positioned in a uniform predetermined relationship with a different
one of said teeth.
7. The multiple lamp unit of claim 5 wherein said motive means
includes a torsion spring coupled to said turntable for rotating
said turntable in said first direction, the rotation of said
turntable in the opposite direction during the replacement of the
burned out ones of said bulbs acting to store energy in said
torsion spring.
8. The multiple lamp unit of claim 1 further including means for
indicating when the last of said plurality of lamps is in said
working position.
9. The multiple lamp unit of claim 8 further including means for
removing electrical power from the unit after the last of said
plurality of lamps burns out.
10. The multiple lamp unit claim 9 wherein said means for
indicating and said means for removing electrical power each
includes a switch and a common member carried by said support
member, said common member actuating said switch included in said
means for indicating when said last lamp is in said working
position and actuating said switch included in said means for
removing power when said support member is incremented after said
last lamp burns out.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to multiple lamp mechanisms for
photographic projectors and more particularly to multiply lamp
mechanisms for photographic projectors in which the mechanism
automatically indexes to a next lamp when the lamp in use burns
out.
Because of their convenience and versatility photographic slide
projectors have achieved widespread acceptance in commercial
ambients where they are often the preferred medium for visual or
audio-visual displays or presentations. Such projectors generally
include a high intensity lamp which directs light through a slide
and a lens for projection on a screen.
Perhaps the most significant weak point of presently available
projectors is the lamp system. If the lamp fails during a
presentation, for instance at a business or sales meeting, the
prededings are interrupted for a ssubstantial time while the
operator removes the burned-out lamp, replaces it with a new one
and then repositions the projector and refocuses the image on the
screen. The problem is even more severe in displays in which the
images projected by a plurality of projectors (in some cases as
many as 70 are focused on a single screen in a coordinated manner.
In this case when a lamp fails, a very noticeable "hole" is left in
the display which destroys the intended visual effect.
Since in presently available projectors access to the lamp is only
from the bottom, the projector must be moved to replace the lamp.
The repositioning and refocusing of the image in such a case is not
a trival matter but requires a good deal of painstaking effort. The
average life time of a popular high-intensity lamp is about 35
hours. In order to guard against lamp failures at inopportune
times, it is the custom to change lamps after 28 to 30 hours. While
this practice does eliminate most of the embarrassing lamp failures
it has many disadvantages. It wastes an average of 5 to 7 hours of
life per lamp and, since these lamps cost about 10 dollars each,
the amount of money involved is significant, especially for
multiple projector installations. Furthermore, since some lamps
fail before 28 hours the problem is not solved completely. This
practice also does nothing to solve the problem of having to
recoordinate the images projected by the projectors of a multiple
unit display.
It has been suggested to provide a projector having a plurality of
lamps which automatically indexes to a fresh lamp when one burns
out. This attempt was abondoned, however, both because it did
nothing to address the problem of having to move the projector to
replace the bulbs and because the indexing mechanism and the
provisions for loading the bulbs were completely impractical.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a
projector in which the failure of a lamp does not disable the
unit.
It is a further object of the invention to provide a practical
automatically indexing multiple lamp projector.
It is a further object of the invention to provide an automatically
indexing multiple lamp mechanism for use with a projector in which
the lamps can be changed without moving the projector.
In accordance with these and other objects of the invention
applicant provides a multiple lamp unit suitable for use with a
photographic film projector which comprises means for individually
and successively transporting a plurality of lamps into a working
position and escapement means for stopping the transporting means
when each successive lamp is brought into the working position. The
action of the escapement means is controlled by means which sense
when the lamp in the working position burns out and which actuate
the escapement means to increment the transporting means for
bringing the next lamp into the working position. The energy for
moving the transporting means is furnished by energy storage means
which supplies energy to the transporting means to move it in a
first direction to bring the successive lamps into the working
position and which receives and stores energy from the transporting
means when it is manually moved in a second direction during the
replacement of the burnt out bulbs by an operator.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of the preferred embodiment of the multi-lamp
projector according to the invention.
FIG. 2 is a bottom view of the lamp mounting and incrementing
assembly of the projector according to the invention.
FIG. 3 is a sectional view of the lamp mounting and incrementing
assembly of FIG. 2.
FIG. 4 is a bottom view of the wafer switch of the lamp mounting
and incrementing assembly of FIG. 2.
FIG. 5 is a back view of the projector of FIG. 1. FIG. 6 shows the
lamp mounting socket of the projector of FIG. 1.
FIG. 7 is a schematic diagram of the electrical portion of the
projector according to the invention.
DETAILED DESCRIPTION
Referring to FIG. 1 of the drawings a slide projector 11 may
include a mirror 13 for directing light through a slide 15
positioned between the mirror 13 and a lens or lens system 17. The
lens 17 projects and focuses the light passing through the slide 15
onto a screen for viewing. The light passing through the slide 15
in the projector 11 according to the invention, is derived from one
of a plurality of lamps 19 mounted below the mirror 13 on a
turntable 21. As seen in FIG. 2 of the drawing the illustrated
embodiment of the invention, six lamps 19 are positioned
equidistantly about the periphery of the turntable 21 on the
underside thereof with only the lamp 19 positioned in the working
location 23, directly below the mirror 13, being energized.
Apertures are provided in the turntable 21 at each lamp position to
allow the light generated by the lamp 19 to pass therethrough. When
the lamp 19 burns out the turntable 21 automatically indexes in the
counter clockwise direction as viewed in FIG. 2 by the distance
between adjacent lamps 19 to bring the next lamp 19 into the
working position 23. Thus the full life of each lamp 19 is used
and, since only a few seconds is required for the indexing
operation, no serious interruption occurs when a lamp 19 burns out.
When the sixth lamp 19 is in the working position a "last lamp"
signal is generated which indicates that it is time to replace the
5 burned out lamps 19. The lamps 19 are mounted face up in the
socket 24 which are affixed to the underside of the turntable 21.
The periphery of the turntable 21 is formed into a 6 tooth ratchet
which cooperates with the double escapement mechanism 25 for
allowing the turntable 21 to index in the counterclockwise
direction by one lamp position when the lamp 19 in the working
positon 23 burns out. The escapement mechanism 25 includes a pair
of identical levers 27 and 29 which are mounted on a common pivot
31 and biased into engagement with the periphery of the turntable
21 by the springs 33 and 35, respectively. Lever 29 normally
engages a ratchet tooth 37 on the peripery of the turntable 21 by
means of the lug 39 for holding the turntable 21 against rotational
movement while the lug 41 on the lever 27 is normally positioned at
a point immediately beyond the next following tooth 37 on the
periphery of the turntable 21. The armature 43 of the solenoid 45
is coupled to the extention 47 of the lever 29.
When the laamp 19 in the working position 23 burns out, the
photocell 49 senses the decrease in light level and causes the
actuation of the solenoid 45 which pulls in the armature 43 and
pivots the lever 29 against bias in the clockwise direction. The
movement of the lever 29 both causes the lug 51 thereon to actuate
the lamp switch 53 and thereby turn off power to the lamps 19 and
disengages the lug 39 thereon form the ratchet tooth 37 thereby
allowing the turntable to rotate in the counterclockwise direction.
The lug 41 of lever 27 is held in contact with the periphery of the
turntable 21 by the spring 33 and stops the turntable 21 when it
engages the next tooth 37. The solenoid 45 is deactuated after 2 to
5 seconds and allows the spring 35 to return the lever 29 into
engagement with the periphery of the turntable 21. The deactivation
of the solenoid 45 also causes the lug 51 on the lever 29 to move
out of engagement with the switch 53 thereby restoring power to the
lamp 19 being brought into the working position 23.
The spring 35 is chosen to be stronger than the spring 33 so that
when the lever 29 is released by the solenoid 45, the portion 55 of
the lever 29 engages the lug 57 of lever 27 and rotates the lever
27 in the counterclockwise direction as seen in FIG. 2 thereby
disengaging the lug 41 of lever 27 from the tooth 37. The turntable
21 then rotates a further small distance until the lug 39 of lever
29 engages a tooth 37 stopping the turntable 21 with the next lamp
19 in the working position 23. With a new lamp 19 in the working
position 23 normal operation of the projector 11 is restored
without the necessity of any repositioning or refocusing.
The removal of power from the lamps 19 during most of the indexing
operation further increases average lamp life since the lamp
filament is most brittle and sensitive to shock when power is
applied.
The member 59 is affixed to and rotates with the turntable 21 for
actuating switches 61 and 63. In the positon illustrated in FIG. 2
of the drawings the sixth (and last) lamp 19 on the turntable 21 is
in the working position 23. In this position the portion 65 of the
member 59 depresses the actuating lever 67 of the switch 61 thereby
generating an indication that the last lamp 19 is in use. As will
be explained in connection to FIG. 6, the actuation of the switch
61 may turn on a last lamp indicator lamp and/or be coupled to
remote point through a connector.
When the sixth lamp 19 burns out the turntable 21 indexes again in
the manner described above and causes the portion 69 of the member
59 to strike the actuating member 71 of the switch 63 thereby
turning off all power to the projector 11 and optionally generating
a "lamps burned out" signal. The switch 63 is fixedly mounted on
the bridge member 73 which is in turn affixed to the underside of
the top plate 75 of the lamp mechanism housing portion of the
projector 11 according to the invention.
FIG. 3 is a sectional view taken through the center of the mounting
structure of the turntable 21. The turntable 21 is rotatably
mounted on the bearing 77 which is affixed to the top plate 75 by
the bolt 79 which extends through the bearing 77 and secures the
stepped shaft 80 to the top thereof. A second bridge member 81 is
fixedly mounted on the turntable 21 for rotation therewith and
carries the rotatable portion 83 of the wafer switch 85 secured to
it by the bolts 87 and 89. The stationary wiper 91 of the wafer
switch 85 is affixed to the upper portion 93 of the stepped shaft
80. The energy for rotating the turntable 21 when the solenoid 45
(FIG. 2) is actuated is stored in the torsion spring 95 which is
wound about the lower portion 97 of the stepped shaft 80. One end
99 of the torsion spring 95 is secured in place by passing through
a hole in the bearing 77. The other end 101 is affixed to the
bridge member 81 and thus to the turntable 21. It is an important
feature of the present invention that when the operator rotates the
turntable 21 as he replaces the burned out lamps 19, he also
provides the energy of indexing the turntable 21 by winding up the
spring 95. When all the lamps 19 are replaced and the turntable 21
is positioned so that the first lamp 19 is in the working position
23 the spring 95 is fully wound and stores ample energy for
indexing the turntable 21 through the five succeeding lamp
positions. Returning to FIG. 2 of the drawings the portion 103 of
the member 59 strikes the portion 105 of the bridge member 73 when
the turntable is fully wound with the first lamp 19 in the working
position 23. This prevents overtightening of the spring 95 and
gives an indication to the operator that the turntable 21 has been
rotated to the proper position.
Referring now to FIG. 4 of the drawings the portion 83 of the wafer
switch 85 which rotates with the turntable 21 includes six
conductive pads 107 arranged circumferentially about the face of
the rotatable portion 83. These pads 107 are electrically connected
to the lamps 19 and cooperate with the stationery wiper 91 to
supply electric power to the lamp 19 in the working position
23.
As seen in FIG. 5 of the drawings access to the lamps 19 may be had
from the rear of the projector 11 according to the invention
through the door 109. When it is time to replace the burnt out
lamps 19, the operator can reach and replace them from the door 109
without moving the projector 11. Also in the rear of the projector
11 there is provided a "last lamp burning" indicator light 111 and
a terminal for coupling such indications as "last lamp burning" to
a remote point such as a central monitoring board for a multiple
unit display.
The lamp mounting mechansim can best be seen in FIGS. 5 and 6 of
the drawings. The lamp 19 is held in position in the socket 24 by
means of a wire frame 114 and may be ejected by pivoting the
ejecting member 115 downwardly against the bias of the spring 117.
This causes the rear portion 119 of its ejecting member 115 to
eject the lamp 19 from the socket 24 for easy removal.
Referring now to FIG. 7 of the drawings the A-C power for operating
the lamp mechanism is obtained from a source 121 which may be
either a direct connection to the line power or a connection to the
circuitry of the projector portion of the unit 11. The latter
choice is preferred. One side of the source 121 is grounded while
the other side is connected to the normally closed OFF switch 63
and the normally open last lamp switch 61. The other side of the
last lamp switch 61 is connected to one side of the last lamp
indicating light 111 and to one terminal of the connector 112. The
other side of the OFF switch 63 is connected through the normally
closed lamp switch 53 to the stationary wiper 91 and rotatable
portion 83 of the wafer switch 85 and thence to the lamp 19 in the
working position 23. The other side of the OFF switch 63 is also
connected to the primary winding of the transformer 123 and to a
second terminal of the connector 112.
The secondary winding of the transformer 123 has a centertap 125
connected to ground and two ends which are connected to the
rectifier 127. The rectifier 127 rectifies the A-C voltage present
at its input to produce a DC B.sup.+ voltage at its input. The
b.sup.+ voltage is in turn connected to the logic circuitry which
controls the operation of the solenoid 45 when the lamp 19 in the
working position 23 burns out.
The photocell 49 senses the light produced by the lamp 19 in the
working position 23 and is connected between ground and is
connected between ground and an input to the amplifier 129. The
output of the amplifier 129 is connected to one input the OR gate
131 whose output is connected to the inverter 133. The output of
the inverter 133 is connected to an input of the AND gate 135 and
to a delay circuit 137. The output of the delay circuit 137 is
connected to the other input of the AND gate 135. The output of the
AND gate 135 is connected to the differentiating circuit 139 whose
output is connected to the monostable multivibrator 141. The output
of the multivibrator 141 is connected to the base of the transistor
143 and to the other input of the OR gate 131. The emitter of the
transistor 143 is connected to ground while the collector is
connected to the solenoid 45. The other end of the solenoid 45 is
connected to B.sup.+.
When the lamp 19 in the working position burns out the output of
the photocell 49 drops. This drop is amplified by the amplifier 129
and coupled through the OR gate 131 to the inverter 133 so that the
output of the inverter 133 goes high. This sets one input of the
AND gate 135 high immediately and sets the other input high after a
delay determined by the delay circuit 137. The delay circuit 137 is
conventional and may for instance include an R-C circuit connected
to a threshold sensitive device. The delay time may be varied by
varying the value of R or C or the level of the threshold and for
the present application is preferably on the order of from two to
five seconds.
When both inputs of the AND gate 135 go high its output is set high
which causes the differentiating circuit 139 to generate a pulse.
This pulse causes the monostable multivibrator 141 to switch to its
unstable state in which its output to the transistor 143 is high
thereby turning the transistor 143 on. This in turn energizes the
solenoid 45 which pulls in the armature 43 thereby releasing the
turntable 21 (FIG. 2) to index under bias and opening the lamp
switch 53. In this manner power is removed from the lamp 19 during
the major portion of the indexing operation. When the output of the
multivibrator 141 goes high it also acts through the OR gate 131 to
cause the output of the inverter 133 to drop thereby removing the
inputs to the AND gate 135 and to the delay circuit 137. When the
monostable multivibrator 141 returns to its stable state
(preferably after an unstable period of 2 to 5 seconds) the
transistor 143 is turned off and the solenoid 45 is de-energized.
This allows the spring 35 (FIG. 2) to return the lever 28 into
engagement with the periphery of the turntable 21 and disengages
the lever 27 from the tooth 37 thereby allowing the turntable 21 to
rotate another small amount until the tooth 37 engages the lug 39
on the lever 29. During this portion of the indexing, power may be
applied to the lamp 19 being brought into the working position 23
since the disengaging of the solenoid 45 allows the lever 29 to
move out of engagement with the lamp switch 53 thereby allowing it
to close.
If, as is occasionally the case, the lamp 19 brought into the
working position 23 is defective and does not light, the output of
the photocell 49 remains low after the output of the monostable
multivibrator 141 returns to the stable state the AND gate 135 is
again actuated and another indexing operation is initiated.
The delay circuit 137 prevents spurious indexing signals from being
generated by the AND gate 135 both when the multivibrator 141
returns to the stabe state and when the projector 11 is being used
in a fade out mode. In this mode the power to the lamps is
decreased gradually over a few seconds rather than being switched
off abruptly. Thus the image projected also fades gradually. At
some point during the fading of the lamp 19 the output of the
photocell 49 drops to a level such that the output of the inverter
133 goes high. The provision of the delay circuit 137 insures that
the output of the AND gate 135 doesn't go high until B.sup.+
voltage has dropped to a level insufficient to actuate the solenoid
45.
As explained above in relation to FIG. 2 when the sixth lamp 19 is
in the operating position, the switch 61 is closed thereby
actuating the indicator light 111 and generating an input on a
terminal of the connector 112. When the turntable 21 indexes after
the sixth lamp 19 burns out the switch 63 is opened thereby
removing all power to the circuitry of FIG. 7.
A manually actuable switch 145 may be provided for manually causing
the incrementing of the lamps 19.
It should be recognized that the above description of the preferred
embodiment of the invention is for purposes of illustration only
and that changes or modifications could be made without departing
from the spirit and scope of applicant's invention. For instance
the turntable 21 could be replaced by a linearly movable lamp
carrier and the torsion spring 95 by a coil spring. Furthermore,
while the multiple lamp mechanism has been described as part of a
slide projector, it could equally well be sold as a separate unit
for attachment to a projector, or be used with units other than
slide projectors. The photocell 49 could be replaced by other means
for detecting lamp burn outs, such as a resistor in series with the
conductor carrying current to the lamp 19 in the working position.
The voltage across this resistor would be an indicator of whether
the lamp was operating properly. Furthermore, in a rather more
expensive embodiment the torsion spring arrangement described in
relation to FIG. 3 could be replaced by a motor drive for the
turntable 21. The illustrated embodiment is preferred however.
* * * * *