U.S. patent number 3,924,120 [Application Number 05/397,219] was granted by the patent office on 1975-12-02 for heater remote control system.
Invention is credited to Charles H. Cox, III.
United States Patent |
3,924,120 |
Cox, III |
December 2, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Heater remote control system
Abstract
A remote control system including infrared transmission means
for coupling control signals simultaneously to remotely located
instruments from a central station via either a plurality of
modulated carriers or digital code words which carry the control
information. The remote control system further includes a control
coordination means whereby the control of various combinations of
instruments can be coordinated. Associated with each instrument is
a separator circuit for selecting only the control signal for that
instrument, and a controlled device operated upon by such selected
control signal and supplying a controlled amount of power to the
instrument. By utilizing an infrared transmission means, and
placing the controlled device with each instrument, the necessity
of installing large numbers of separate, independent circuits is
eliminated, and increased flexibility of control is achieved.
Inventors: |
Cox, III; Charles H.
(Arlington, MA) |
Family
ID: |
26924171 |
Appl.
No.: |
05/397,219 |
Filed: |
September 14, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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230378 |
Feb 29, 1972 |
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Current U.S.
Class: |
398/98; 398/109;
398/190; 398/166; 340/13.37 |
Current CPC
Class: |
H05B
47/195 (20200101); G08C 23/04 (20130101) |
Current International
Class: |
G08C
23/04 (20060101); H05B 37/02 (20060101); G08C
23/00 (20060101); H04B 009/00 () |
Field of
Search: |
;250/199 ;315/292,316
;317/124,127 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Griffin; Robert L.
Assistant Examiner: Psitos; Aristotelis M.
Attorney, Agent or Firm: Paul & Paul
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of my co-pending U.S. application
Ser. No. 230,378 now abandoned, filed Feb. 29, 1972, titled THEATRE
LIGHTING CONTROL AND DIMMER SYSTEM.
Claims
I claim:
1. In a theatre system having a plurality of theatre instruments,
an optimal control system for simultaneously operating select ones
of said instruments at any level in the operational range thereof
while maintaining optimal flexibility in location of said
instruments, said control system comprising:
a. a plurality of instruments located at respective positions in
the theatre, each having a different identification code and each
including a photosensitive detector, a digital signal decoder, and
an actuation control means;
b. a source of signals, said signals representing specified
variations in the operation of select ones of said instruments;
c. means for converting said signals from said source to a
predetermined digitally coded signal, said code being conditioned
to energize actuation control means to bring said instruments
selectively to desired operating levels, said means for converting
including means for multiplexing signals for a plurality of
instruments into an aggregate digital signal of predetermined
format to associate control information for a given one of said
instruments with the corresponding identification code;
d. optical transmission means including means for translating said
aggregate signal into infrared energy, and at least one continuous
optical transmission path between said means for translating and
each of said photosensitive detectors, whereby transmitted
aggregate signals from said optical transmission means contain all
actuation control level change information for said theatre, and
individual ones of said instruments are conditioned to extract
corresponding infrared control signals and to reject infrared
control signals which correspond to other ones of said
instruments.
2. A system as described in claim 1 wherein said means for
converting includes means for producing actuation control level
change information in the form of with binary code words uniquely
associated with corresponding ones of said instruments, said binary
code words representing said identification code, and wherein the
digital signal decoder of each said instruments includes logic
means energized only by a binary code word associated with the
corresponding instruments.
3. A system as described in claim 2 wherein said means for
converting includes means for identifying all ones of said
instruments having the same prospective actuation control level
change, and wherein said multiplexing means includes means for
grouping all binary code words of a given prospective actuation
control level change with a digitally coded signal of said given
prospective actuation control level change.
4. A system as described in claim 2 wherein said multiplexing means
includes means for aggregating all binary code words of said
instruments followed respectively by coded corresponding
prospective actuation control level changes for said
instruments.
5. A system as described in claim 1 wherein each of said
instruments comprises means for sampling said transmission path at
predetermined unique periodic intervals, and wherein said
multiplexing means includes timing means for transmitting coded
intensity change information only during the intervals during which
the corresponding instruments is conditioned to sample said
transmission path, the identification of said unique periodic
intervals constituting said identification codes.
6. A system as described in claim 1 wherein each of said
instruments is connected to said means for translating by a
different transmission path, and wherein said means for
multiplexing includes means for coupling said means for translating
to any given one of said different transmission paths to
selectively couple actuation control level change information to a
corresponding given one of said instruments, coupling being
accomplished on the basis of said different identification
codes.
7. A system as described in claim 1 wherein said plurality of
instruments are lighting instruments, said actuation control level
change information being light intensity change information.
8. A system as described in claim 1 wherein each of said
instruments is self-clocking, being conditioned to sample said
transmission path at intervals derived from the format of the code
itself and wherein said multiplexing means includes timing means
for transmitting coded intensity change information only during the
intervals during which the corresponding instruments is conditioned
to sample the said transmission path, the identification of said
sampling intervals constituting said identification code.
9. In a theatre system having a plurality of theatre instruments,
an optimal control system for simultaneously operating select ones
of said instruments at any level in the operational range thereof
while maintaining optimal flexibility in location of said
instruments, said control system comprising:
a. a plurality of instruments located at respective positions in
the theatre, each being associated with a photosensitive detector,
a carrier demodulator, and an actuation control means;
b. a source of signals representing specified variations in the
operation of select ones of said instruments;
c. transmitter means, comprising a plurality of high frequency
carrier generators, each generating a respective different carrier
and each being modulated to carry information of the control signal
of one of said control units;
d. infrared transmission means, comprising a non-coherent infrared
signal emitter and an optical transmission path to all of said
instruments, for providing continuous signal transmission from the
location of said transmitter means to the location of said light
instruments;
e. a plurality of infrared detectors located respectively at the
locations of said light instruments; and
f. control signal separation means, connected to respective ones of
said detectors, for separating at each said instrument a given one
of said transmitter carriers, deriving the control signal carried
thereon, and coupling said control signal to the controlled device
positioned with said instruments.
10. A system as described in claim 9, wherein:
a. said transmitter means comprises a plurality of low frequency
subcarrier generators, signals from each such subcarrier generator
being modulated by respective said control signals, the modulated
subcarriers being multiplexed onto signals at said carrier
transmitters so that said carriers are modulated to carry said
modulated subcarriers; and
b. said separation means has a tunable high frequency band pass
filter to separate out one of said carriers, and a low frequency
band pass filter to separate out a specific one of said
subcarriers.
11. A system as described in claim 9 wherein said plurality of
instruments are lighting instruments, said actuation control level
change information being light intensity change information.
Description
BACKGROUND OF THE INVENTION
A. Field of the Invention
This invention lies in the field of remote control systems and,
more particularly, theatre control systems where all control
signals are transmitted together over a common transmission medium
and each instrument is controlled by separation of a specific
control signal and control of a controlled device at the location
of such each instrument.
B. Description of the Prior Art
Theatre lighting, being an integral part of each theatrical
performance, or show, requires an implementation with sufficient
flexibility to cover the demands of each show produced, and thus
any given theatre lighting system must be sufficiently flexible to
cover a wide range of different types of shows. A lighting system
must provide visibility in different degrees, must provide
composition and naturalism, and is essential in providing the
overall atmosphere, or mood of the production. Specifically, each
instrument used in lighting a given theatrical production has a
particular function, e.g., being a solo spotlight, providing a
particular effect such as a setting sun, etc. In order to obtain
maximum flexibility, each instrument must be subject to separate
control, i.e., through its own dimmer. To coordinate intensity
changes in a large number of instruments, which instruments are
separately located, the standard system has a master control board
for control of the dimmers, with a separate circuit from each
dimmer to the remote position of the respective instrument.
In the construction of a theatre, it is not conceptually possible
to anticipate the maximum number of circuits required at any given
location in a theatre for any given show, nor is it economically
feasible to install large numbers of circuits which will only be
utilized on rare occasions. Consequently, present theatre lighting
systems are based on the requirements of an average show, such that
large multiconductor cables are installed to the most likely
lighting positions. Typically, a total of from 100 to 600
individual circuits are installed, connecting from 50 to 150
dimmers to lighting instruments located throughout the theatre. A
patch panel, which is essentially a high powered analog of a
telephone switchboard, allows any circuit to be connected to any
dimmer. Provisions are also made on the patch panel for more than
one circuit, usually between 2 and 6 circuits, to be connected to
the same dimmer. Connecting more than one lighting instrument to
the same dimmer, however, tends to limit the effectiveness of the
instruments, since they cannot be individually programmed.
Unfortunately, few shows are average, such that the specific needs
for a given show are rarely met with the installed system. Thus,
when more lights are required at a given location than there are
circuits leading to such location, the system is inadequate. Two
options do exist in such an instance, namely connecting a plurality
of instruments together, or temporarily installing extension cords
so as to "borrow" or transfer circuits from other locations to the
location where extra circuits are needed. Both of these
alternatives result in a serious loss of flexibility, as well as
increased installation time and expense.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a remote control
system providing optimum flexibility in placement of instruments
and control of such instruments, and which is simplified and
inexpensive in comparison to prior art remote control systems.
It is further an object of this invention to provide a remote
control system wherein control signals for all of the instruments
in the system are generated at a remote control location, with all
of the control signals being transmitted to respective instruments
via infrared light such that separate cables are not necessary, and
wherein controlled devices are mounted contiguous to or located
near to each instrument and are individually and simultaneously
controlled by the transmitted control signals.
It is yet another object to provide a control system for
simultaneously operating select ones of a plurality of instruments
to any level in their respective operational ranges, i.e., either
"on-off" or at any level therebetween, as desired.
Finally, it is another object of this invention to provide means
for coordinating the control of many remotely located
instruments.
In accordance with the above objects, there is provided a remote
control system wherein each of the instruments in the theatre are
controlled by a control device positioned contiguous or near
thereto, each instrument being connected to a source of power, for
example a battery or the theatre system power line with control
means positioned at a point remote from said instruments and
containing control units for generating control signals for each of
such instruments. In one embodiment, the control signals modulate a
carrier (or carriers) which are transmitted from such remote
position to the respective instruments. In another embodiment, a
plurality of subcarriers are generated, each modulated by
respective control signals, the subcarriers in turn being combined
or multiplexed on a plurality of carriers. In still another
embodiment the control signals are transmitted digitally in the
form of binary code words.
In a preferred embodiment, infrared transmitters and receivers are
utilized. In the environment of a theatre, which has cavernous open
spaces, use of infrared transmission allows for application of the
principles of the present invention to control speaker systems,
self propelled mobile stage props, and the like, as well as to
lighting systems and apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the theatre system of this
invention.
FIG. 2 is a block diagram showing the arrangement of the control
signal generators and transmitters as used in this invention;
curves (a), (b), (c) and (d) in FIG. 2 illustrate the signal
waveforms at corresponding points.
FIG. 3 is a modification of FIG. 1, showing an embodiment wherein a
plurality of carriers and subcarriers are generated to carry the
control signals which are sent to the light instrument dimmers.
FIG. 4 shows an alternative illustrative embodiment utilizing
infrared transmission of digital pulses.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The devices to be controlled are distributed throughout the
theatre. There is illustrated in FIG. 1 a plurality of lighting
instruments 30, shown connected to a pipe 31 which provides
mechanical support of the instruments. The variety of such
instruments, and the manner of support of same, are choices
available to the user and are, as such, not essential to this
system. Hereinafter, the terms "devices" and "instruments" are used
interchangeably to describe the apparatus being controlled. Each
instrument 30 is electrically connected to the transmission line 25
from a normal electrical plug 28, the connection being made through
an instrument control unit 50, the details of which are described
hereinbelow.
Remote from the instruments 30, and centrally located to optimum
advantage of the operator of the system, are a plurality of control
signal generation units 40. Each unti 40 is an electronic system
designed to generate a control signal, which control signal is in
turn transmitted to at least one lighting instrument, to actuate a
control device connected to same. Each control unit 40 produces a
distinct control signal, which signals are programmed by the system
operator. The outputs of the control units 40 are suitably
connected through a patch panel 45 to a plurality of
modulator-transmitter (M/T) units 41. Each unit 41 contains a
generator for generating a carrier at a specified frequency, and a
modulator which receives a control signal from one of the units 40,
which control signal is caused to modulate the carrier signal. The
outputs of the units 41 are coupled to an infrared emitter which
radiates the plurality of modulated carrier signals. The infrared
light may be reflected, focused, and/or carried via light pipes as
required by a particular installation.
The output from the infrared emitter which is transmitted to all of
the infrared detectors/receivers 51 located adjacent to lighting
instruments 30, contains a plurality of carriers, each carrying a
control signal. In operation, there are as many carriers as there
are different control signals to be sent to the control devices
associated with each instrument light. Thus, the infrared light
detector/receiver at each instrument picks up all of the different
carrier signals. These signals are first connected to a control
signal separator, unit 51. Unit 51 also contains a tuned band pass
filter which separates out one specific modulated carrier signal,
which is connected through to the demodulator and amplifier unit
52. Unit 52 recovers the control signal, and connects same to the
control input of the controlling device 53. Thus, the control
signal is communicated to the controlling device, the power output
of which is connected to instrument 30. Thus, for a particular
instrument 30, that control signal which is carried by the carrier
frequency corresponding to its tuned band pass filter, is detected
and caused to control the operation of the instrument, e.g.,
control the light intensity. Each other instrument has associated
with it an instrument control unit 50, containing in its signal
separator a band pass filter tuned to a different frequency, so
that it can be controlled uniquely of all other instruments in the
theatre. Thus, if desired, every instrument 30 can be separately
controlled. It is to be noted that, in practice, it may be desired
to have a number of separate instruments commonly controlled, in
which case the respective carriers for each such instrument carry
the same control signal. This is achieved by proper patching at the
control station.
The controlling device 53, as used in the system of this invention,
could be an SCR dimmer, the details of which are well known and
need not be specified herein. See, for example, the General
Electric SCR Manual, Second Edition, pages 119 and 120. In the
typical SCR dimmer as presently used in theatres and other
applications, the dimming may be manually controlled by varying the
time or phase delay which controls the dimming (or portion of each
cycle that the power current is passed through the SCR).
Alternately, the delay in turn-on time of the SCR, relative to the
start of power half cycle, may be controlled by an externally
generated control signal. To accomplish this, it is necessary only
that the control signal carry information as to when, for each half
cycle of the power signal, the SCR is to turn on.
It should be noted that the control units 50, as well as the
instruments being controlled, may also be battery powered, for the
use of infrared radiation obviates the need for any fixed physical
positioning or fixed electrical connection of the instrument being
controlled.
By referring now to FIG. 2, a manner of generating the control
signals used in this invention may be seen and understood. The 60
Hz power signal, (shown at a), is connected to the input of a
frequency doubler 38 which generates a 120 Hz signal. The 120 Hz
signal is connected to a halfwave rectifier and squarer 43, the
output of which is illustrated at b. The 120 Hz squarewave thus
produced is connected to the input of a variable monostable
flip-flop 46 within a control unit 40. Flip-flop 46 is set into its
temporary state at the start of each positive going portion of the
squarewave, i.e., at the start of each cycle of the 120 Hz signal.
The flip-flop remains in its temporary state for a length of time
determined by the setting of a controller 44, suitably a manually
operated potentiometer. Thus, the flip-flop returns to its stable
state after a predetermined time period, corresponding to the
desired delay before the SCR in the dimmer 53 is to be turned on.
The output of flip-flop 46 is shown at c, with the controllable
time delay interval shown as D. As is known, the inverse of the c
signal, designated as c, is also available (or can be generated by
passing the c signal through an inverter). Consequently, the c
output comprises a train of positive pulses, the duration of each
positive pulse corresponding to the setting of its controller 44.
When, and only when this control signal is received at the SCR
dimmer 53, does the SCR therein conduct, such that power current is
provided to the instrument light 30 only during the positive
portion of the control signal, or after the time delay D. By using
a pair of back-to-back SCRs in the dimmer, a controlled power
signal is sent to the light instrument 30 each half cycle of the
power current.
Other forms of control signals are obviously possible within the
scope and spirit of this invention. For example, zero-point or
synchronous switching of SCRs is another common triggering
technique. As its name implies, zero-point switching turns the SCR
on only when the voltage is zero (turn-off is always at a zero),
thus avoiding the sharp transient associated with phase or delay
switching. Multilevel control is afforded by only triggering the
SCR for a fraction of the number of cycles in a fixed interval. For
example if the fixed interval is ten cycles of the 60 Hz line
frequency, a setting of half on the controller 40 would cause the
SCR 53 to conduct on 5 of the 10 cycles; a controller setting of
0.05 would cause the SCR to conduct for only one half cycle over
the 10 cycle interval.
When the source of power is DC, some means will have to be provided
to turn the SCR off, since with DC, the voltage obviously does not
periodically drop to zero. Alternatively, a silicon controlled
switch, SCS, which differs from an SCR only in that it also has an
off gate, could be used.
All three of the above approaches are well known in the art and
hence will not be discussed further here.
The control signals thus generated are connected through patch
panel 45, and modulate the output of transmitter 48 by operation of
conventional electronic switch 49, or other modulator means. The
output of the entire modulator unit 41 is thus a pulse modulated
carrier, with an envelope corresponding to the c control signal.
Each of such pulse modulated carriers, at their respective
frequencies, are added together and fed to the infrared emitter. By
this arrangement, each SCR dimmer corresponding to a respective
lighting instrument 30 receives a corresponding control signal
transmitted on that carrier frequency corresponding to the tuned
filter associated with that light instrument. In this manner, each
light 30 is independently controlled by the setting of a controller
44, such that the system operator can control simultaneously all of
the lights from one centralized position.
In a situation requiring a large number of instruments, e.g., 400,
to be controlled simultaneously and independently, the use of
individual carriers to carry the control information for each
instrument is cumbersome. Two alternatives are available --
multiplexing and direct digital encoding. Further, two types of
multiplexing are well known -- frequency multiplexing and time
multiplexing. Since these types of multiplexing can be shown from
an information theory point of view to be equivalent only the
former will be discussed herein.
Referring now to FIG. 3, an alternate embodiment of this invention
employing frequency miltiplexing is illustrated. In this
embodiment, a limited number of main carriers, suitably just two,
are utilized. This contrasts with the system as described above,
where there are as many carriers as there are light instruments. In
this embodiment, each control signal modulates a low frequency
subcarrier, the modulated subcarriers in turn being connected to
and modulating a transmitter producing a main carrier. Thus, in
FIG. 3 there are illustrated two main carrier generators 68, and
three subcarrier generators 65. It is to be noted that in a
preferred embodiment there are as many different combinations of
subcarriers and carriers as there are light instruments, so that
the system has capacity to separately control each such instrument.
Thus, if there are 64 light instruments to be controlled, and two
main carriers, ideally there will be 32 different subcarrier
generators 65.
The output of each subcarrier unit 65 is connected to two modulator
units 67, each of which modulates in accordance with a separate
control signal connected thereto. Thus, from each subcarrier, there
are produced two modulated signals. One of each subcarrier is then
summed through respective summers 66, the outputs of which are
coupled to the main carrier modulator-transmitters (M/T) 68. Thus,
each main carrier carries each of the subcarrier frequencies.
In this embodiment, the outputs of units 68 are connected to the
infrared emitter or transmitter such that both main carriers are
transmitted to all of the instrument control units. At each
instrument, the control signal is passed through a tunable band
pass filter 76, designed to be tunable to one of the two main
carrier frequencies available for selection. An advantage is
achieved here in that high frequency broad band pass filters are
much more economical than the high frequency narrow band pass
filters required where each instrument has its own high frequency
carrier. The output of filter 76 is coupled to the carrier
demodulator 55. There, the carrier is demodulated, the subcarriers
are amplified, and one of the subcarriers is selected by a low
frequency, (e.g., audio), narrow band pass filter 77. The selected
subcarrier is then demodulated by demodulator 78, to derive the
control signal which is connected to the controlling device. The
power line 25 supplies 60 Hz power current which is connected
through to the controlling device.
The advantage of this embodiment of the system lies in the fact
that narrow band pass filters at low frequencies are readily
available and a large number of subcarriers can be accommodated.
For example, there are available commercial filters providing
excellent narrow band characteristics at 15 Hz intervals. Thus, 100
to 200 subcarriers could very efficiently be accommodated in this
system. By contrast, where each lighting instrument has its own
high frequency carrier, it would be necessary to generate such
carriers over a wide range of frequencies since it is difficult to
obtain narrow band filters at higher frequencies.
Another advantage of this embodiment is that it offers an
additional means for controlling various combinations of
instruments together. By simply tuning the high frequency bandpass
filters to the same frequency, two instruments will receive the
same signal and hence operate together. This would be useful in a
theatre application for example when it is desired to control the
illumination of large areas which require many lighting
instruments.
While the above discussion had the high frequency filters tunable
and the low frequency filters fixed, obviously the situation could
be reversed, making the low frequency filter tunable and the high
frequency filter fixed. Further, both could obviously be made
tunable.
Another alternate embodiment of this invention employing direct
digital modulation will be presented below. See FIG. 4. As
previously disclosed, the controller 401 produces a signal which
can be connected to various digital encoders 402, 403, 405, etc.
The encoders, whose outputs are coordinated by the sync and timing
box 406, transform the controller 401 output into a suitable form
for transmission. An example of such a transformation would be the
addition of redundant information which could be subsequently used
by the decoder to reduce the probability of a transmission error.
The outputs of all the encoders 402, 403, 405, etc., feed the
infrared emitter 407 which radiates or transmits the information.
If, for example, a binary code was used in the encoders 402, 403,
etc., then the control information is in the form of 0's and 1's
with the corresponding infrared emitter 407 output being a sequence
of "on" and "off" flashes. At the receiver the infrared radiation
is detected at a detector 408, decoded at 409, and fed to the
controlling device 411.
The actual information content of the transmitted signal will of
course vary considerably depending upon the application. In the
context of controlling lighting instruments, such as 412, several
examples of the information transmitted are to be given.
The use of light emitting diode (LED) photo-transistor systems also
makes direct digital transmission much more feasible. In such an
all-digital system, no carriers or subcarriers are used; instead
the information is put in the form of a binary code which in turn
is fed directly to the LED, thereby switching it "on" and "off."
Whereas in the case of analog modulation, a specific instrument was
identified by a certain carrier frequency (or carrier frequency and
subcarrier frequency combination), with digital modulation each
remote control unit is identified by a binary code word (or some
combination of several binary words), as in the following
examples.
Example I: Transmit each instrument number, and the corresponding
intensity. The transmitter would send each instrument number,
followed by the intensity at which that instrument should be set.
With a large number of instruments, this is obviously quite a
redundant scheme, i.e., with 320 instruments, each of which has
control levels, this means that the same intensity will be
transmitted 320 times if all instruments are to be at the same
intensity.
Example II: Transmit all instrument numbers of same intensity,
followed by the desired intensity. This scheme involves
transmission of a sequence of instrument numbers followed by a
single intensity at which all the previously listed instruments
should be set. Thus, this scheme involves division of the
transmitted information into frames, each frame including a full
set of numbers of instruments to be changed with corresponding
intensity changes.
Both of the above schemes still involve considerable redundancy
since each instrument must "know" its number, in order to recognize
its number when transmitted, such as by means of selective logic
means. If the intensities are transmitted in a rigid sequence,
i.e., instrument No. 1's intensity is always transmitted first,
instrument No. 2's second, etc., then a further simplification can
be made. This can be done in at least two ways:
Example III: Transmit intensity, common sync. If a common frequency
is available at the transmitter and all receivers, then this
frequency can be used to sync the transmitter and receiver. The
line frequency is an obvious example.
Example IV: Transmit intensity, self clocking. If some instruments
are to be battery operated, for example, then a self clocking code,
such as a return to zero code, could be used. In a return to zero
code, the level goes to zero between every bit, whereas in
conventional binary code the level goes to zero only where the
binary zero is to be transmitted. Hence, in a return-to-zero code,
the same number of edges get through, independent of the
information being sent, and thus these edges can be used to drive
or to sync the oscillator at the instrument.
One additional embodiment, which will work under limited
conditions, is that the infrared signal can be used directly to
control an SCR. Such an embodiment requires a highly directional
infrared emitter, such as a laser.
In the foregoing embodiments, it clearly is not necessary for power
lines to be connected directly between the transmitter and the
receiver. Rather, all that is required is a continuous optical
circuit therebetween, furnished either by open space, mirrors,
lenses, fiberoptic bundles, or the like. In most practical
situations, the theater affords ample volume for line of sight open
space transmission.
Normally, the light-emitting diode (LED) only need be coarsely
focused, such as by a 45.degree. beam to on stage instruments and a
180.degree. beam for orchestra and stage footlights. As desired,
receiving phototransistors conveniently may be mounted at one end
of a black flat finished tube pointing toward the transmitter.
Lenses generally are required only for receivers more than 50-100
feet from the transmitter, in accordance with the present state of
the art.
The system as thus shown above, in each of the embodiments, is seen
to provide great flexibility in allowing the instruments to be
connected anywhere in the theatre, and without having to install
any connecting cables or circuits. The efficiency of such
installations can be improved even further by packaging the
instrument control units 50, which include the controlling device,
for mounting directly to or on the instrument. By thus integrally
connecting the instrument control units to the instruments
themselves, there is provided a single package which need only be
mechanically supported at the position where it is to be installed.
This feature provides optimum installation efficiency, and answers
a long and seriously felt need for increased flexibility in theatre
lighting systems.
While the preferred embodiments of this invention have been
presented in their specifics, it is recognized that variations of
specific components of the system may be made within the spirit and
scope of the invention.
Even more importantly, the technique of digitally encoding time
delay signals makes it possible to directly interface the system
with a digital computer, by coding digital words in computer memory
to carry the time delay information. For example, a digital memory
80 (FIG. 2) may have stored therein 32 different time delay words,
each being a 5 bit word and corresponding to the division of one
half the power system period (1/120th second) into 32 fractions
thereof. When a given delay is desired (corresponding to a given
percentage of full power), the operator may simply read out of the
memory the desired word, which is used directly to pulse code
modulate a carrier. At the receiving end, a conventional
digital-to-analog device is used to generate an appropriate analog
control signal which is used to control the SCR dimmer. The
technique of read in and read out of a computer, or digital memory,
is well known in the art, and need not be amplified further in the
specification in order that this be a proper enabling
disclosure.
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