Apparatus and method for producing a frequency based visual effect

A variable lighting apparatus for visually simulating and translating the frequencies present in an input signal to a light, the characteristics of which may be varied in accordance to the properties of the input sound. The lighting apparatus may be fitted with a plurality of filter channels for filtering the input signal into preselected bands. Each channel may then drive an independent light, each of which may be differently colored and will respond individually to the frequency components of the input signal determined by the filtering channel to which it is attached. The frequency response band and sampling characteristics of each filter may be adjusted to provide for a variable visual effect.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The method and apparatus of the present invention relates generally to 
lighting effects. More specifically, it relates to an apparatus and method 
for producing a lighting effect which varies according to the components 
of the input signal. If the input signal is sound, the apparatus is 
capable of splitting the incoming sound signal into a plurality of 
frequency components and using each of these frequency components to 
generate a light control signal. The light control signal may then be used 
to vary the flashing or enabling period of an individual light. This 
provides a unique lighting effect which differs significantly from merely 
varying the light's intensity. The apparatus may be configured for use in 
either a home or commercial setting. 
Currently, lighting effects are generally confined to producing a light 
which will flash independent of the amplitude of the input sound sensed 
and usually do not discriminate according to various frequency components 
in the signal. Additionally, lasers have recently begun to appear in 
lighting shows. However, lasers, although aesthetically pleasing, are 
somewhat dangerous to use in a crowded environment. Further, lasers 
depending on power and illumination source can be quite expensive to 
purchase. 
2. Description of the Prior Art 
Prior art devices coupling a variable lighting unit to a sound source are 
well known in the art. However, generally these prior art devices are 
limited to varying the light pulse frequency or amplitude independent of 
the amplitude of the input sound signal. Even simpler devices provide for 
a strobe light which flashes at a predetermined frequency independent of 
the input sound signal. 
An example of this type of prior art is illustrated in Charas U.S. Pat. No. 
3,838,417. The Charas invention discloses a flashing strobe light which 
flashes at an operator-selected predetermined frequency. The flash 
frequency is independent of the audio signal. The invention also discloses 
a means for flashing a plurality of colored lights wherein the color 
flashed is dependent on the flashing frequency. However, as is typical of 
many prior art devices, no provision is made for directly associating the 
frequency of flashing or the color of light being illuminated to the input 
sound signal. 
An example of a more sophisticated prior art device is Blattner U.S. Pat. 
No. 1,654,068 which discloses an apparatus for visually interpreting 
speech and music. Blattner discloses a device which may be attached to a 
music source by means of a filter system which separates the sound signal 
from the source into three distinct bands. The outputs from these three 
filter bands are used to drive three lamps which may be of different 
colors. The intensity of the light assigned to a given frequency band is 
determined by the intensity of the input sound signal at that frequency. 
However, there is no means provided for flashing or enabling the colored 
lights at a frequency corresponding to the amplitude of the signal at a 
given filter frequency band. The visual effect presented by Blattner by 
varying the intensity of the lights is completely different from that 
provided by flashing or strobing a light off and on. 
None of these prior art lighting systems teach the unique visual effect of 
the present invention whereby an input signal may be separated according 
to some predetermined characteristics such as frequency and wherein these 
characteristics can be used to drive a flashing light apparatus. 
Consequently, it is a primary objective of the present invention to provide 
an apparatus which is capable of receiving an input signal, separating the 
input signal into a plurality of frequency bands, and assigning each 
frequency band output to a specified colored light. The colored light in 
that frequency band may then flash during an enabling period which is 
proportional to the amplitude of the output of the signal in that 
frequency band providing a unique visual effect. 
Another objective of the present invention is to provide a lighting 
apparatus which may control the flash rate of the light in proportion to 
the amplitude of the signal in an associated frequency channel. 
A further objective of the present invention is to provide a variable light 
apparatus which is capable of driving conventional illumination means. 
An additional objective of the present invention is to provide a variable 
light apparatus which is capable of receiving a sound signal either by 
direct electrical coupling of the lighting apparatus to the sound source 
or by means of an acoustical coupling to the sound source such as through 
a microphone. 
A further objective is to provide a lighting apparatus wherein the lighting 
colors assigned to a frequency filter band may be adjusted. 
An additional objective of the invention is to provide an apparatus which 
is capable of adjusting the sampling rate cf the input sound signal such 
that the precision with which the lighting apparatus tracks the incoming 
signal may be adjusted. 
A further objective is to provide an apparatus which is adaptable for use 
in either a home or commercial setting. 
A final objective of the invention is to provide a means for adjusting the 
conversion factor between the amplitude of the frequency component and the 
flash frequency or enabling period of the associated light. 
SUMMARY OF THE INVENTION 
The variable lighting apparatus of the present invention provides a means 
for visually simulating and translating the frequencies present in an 
input signal to a light, the display characteristics of which may be 
varied in accordance to the properties of the input signal. The lighting 
apparatus of the present invention includes an input means for 
electrically inputting a signal to be simulated. A gain control means may 
be electrically connected to the input means and provides an adjustment of 
the amplitude of the input. A plurality of means may be electrically 
connected to the gain control means and selectively filter frequencies 
from the input signal. A sampling means is electrically connected to the 
filtering means obtaining a sample of said input sound. The sampled signal 
is to a converter means for converting the filtered sample of the sound 
input into a variable frequency output, the frequency of which varies in 
proportion to amplitude of the filtered sample of the input. A pulsing 
means is connected to the converter generating a sequence of flashing 
pulses, the frequency of which determined by the output of the converter 
means. Finally, a light means is electrically connected to the pulsing 
means whereby the light is flashed in response to the variable output 
frequency of the converter means corresponding to the amplitude of the 
input that frequency band. 
The method of the present invention includes providing a lighting apparatus 
capable of selectively separating an signal into desired frequency 
components and converting the amplitude of the input signal in that 
frequency band into a flash rate which is proportional to the amplitude of 
the signal in that band. The method further provides for adjusting the 
sampling rate of the apparatus such that the precision with which the 
apparatus follows changes in the input signal amplitude may be altered. 
Finally, the method allows the flash rate as a function of signal 
amplitude to be adjusted.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
1. Theory of Operation 
The theory of operation of the present invention may be summarized as 
follows. An input signal comprising sound or other periodically varying 
signal is input to the apparatus. The input signal may be coupled to the 
apparatus by direct electrical connection or the coupling may be effected 
indirectly through a microphone or other transducer. The signal may then 
be amplified as desired. The frequency components of the input signal are 
then segregated into a plurality of frequency channels (preferably three 
although a single filtered/channel may be used) using conventional 
filters. A sample and hold circuit then periodically samples the amplitude 
of the signal present in each of the filtered channels. The sampled 
amplitude of the signal is then used to drive a variable period clock, the 
period of which is proportional to the amplitude of the signal present in 
the filter channel. This period, referred to as the enabling period, then 
controls the flashing period of a respective strobe light. The flashing 
frequency during the enabling period is set by the operator. In one 
embodiment the flash frequency of the light would be considerably higher 
than the amplitude driven enabling period. In that case the light will 
flash numerous times during the enabling period. Alternatively, the flash 
rate of the light may be adjusted to be relatively slower than the 
enabling period and therefore the flashing of the light may be tied more 
directly to the enabling period and thus the amplitude of the filtered 
signal. 
2. Preferred Hardware Design 
FIG. 1 shows a block diagram comprising the major components of the 
invention 100. As seen in the figure, an input microphone 10 is used to 
acoustically couple a sound source to the light control apparatus 100. 
Provisions in the preferred circuitry also allow for the direct electrical 
coupling of a sound source to the lighting apparatus 100 without the need 
for an acoustical coupling device such as microphone 10. Additionally, the 
input signal is not restricted to sound but may be any variable signal 
such as pressure, temperature or the like. Either directly from the 
source, or through acoustic coupling device 10, the input signal is then 
fed to a voltage gain control 20. Gain control 20 conditions the amplitude 
of the input signal to be compatible with the remaining circuitry. Gain 
control 20 is entirely optional, its use being determined by strength. 
After conditioning by optional gain control 20, the signal is then fed to 
three parallel, band filters 30a-c. In the preferred embodiment, the input 
signal is separated into three components but obviously more may be used 
to create a different effect. Alternatively, in some situations, a single 
channel may also produce desired effect. In that case the apparatus would 
operate by passing only a single band of frequencies. 
As is well understood in the art, filters 30a-c are constructed to pass a 
certain band of frequencies depending on the design parameters of each 
filter. For example, in the preferred embodiment, filter 30a is a low-pass 
filter which passes signal frequencies between approximately 20 and 400 
Hz, filter 30b is a mid-band pass filter which passes frequencies from 
approximately 400 to 1,500 Hz, and filter 30c is a high-pass filter which 
passes frequencies between approximately 1,500 and 20,000 Hz. High pass 
and low pass channels may also have additional amplifiers 40b and 40a 
respectively to provide additional amplification of the filtered signal. 
After filtering and amplification, the input signal is passed to sample and 
hold circuitry 50a-c. Sample and hold circuitry 50a-c is operative to 
sample the analog signal output from amplifiers 40a and 40b and filter 30b 
and present a DC output proportional to the analog input during the sample 
period. The sample and hold time periods for sample and hold circuitry 
50a-c are determined by the component values used in the circuitry 
discussed more specifically below. The frequency of the sample and hold 
function affects the precision with which the output of the sampler tracks 
the changing amplitude of the input signal. For example, if the amplitude 
of the input signal is changing rapidly, the sampling rate (frequency) 
must also be higher in order to accurately represent the sampled signal. 
After the filtered input signal has been sampled by sampling means 50a-c, 
the sampled signal is fed to light controller means 60a-c. Light 
controller means 60a-c is operative to convert the DC voltage output from 
sampling circuitry 50a-c into a variable frequency square wave, the 
frequency of which varies in direct proportion to the DC voltage output 
from sampling circuitry 50a-c. This variable frequency square wave defines 
the enabling period. The variable frequency square wave from light 
controller means 60a-c is then fed to lights 70a-c. In the preferred 
embodiment, lights 70a-c would be different colors to enhance the visual 
light effect. Light controller means 60a-c is operative to control the 
flash period of light means 70a-c. The square enabling pulse from light 
controller means 60a-c enables lights 70a-c. Thus, this enabling pulse 
determines the period during which light means 70a-c will strobe at the 
preset frequency. The strobing frequency of the lights 70a-c during the 
enabling period is determined by additional circuitry described below and 
may be adjusted by the operator. Thus, light means 70a-c is strobed at a 
preselected frequency for a period of time representative of the amplitude 
of the signal in each respective filter channel. As mentioned above, 
suitable adjustment of the preset light strobing frequency relative to the 
enabling period will effectively cause the flashing frequency of the light 
to be determined by the amplitude of the filtered signal. 
FIG. 2 is a front elevational view showing the apparatus of the present 
invention enclosed in case 18. The embodiment shown in FIG. 2 would be 
used in a commercial setting. In that situation, case 18 may be secured by 
means of bracket 26, to the ceiling or some remotely controllable fixture. 
The embodiment shown in FIG. 2 would be that used in a commercial setting. 
As seen in the figure, the lighting apparatus of the present invention 
fits compactly in a relatively small and transportable case 18. As shown 
in the figure in the preferred embodiment, strobe lights 12, 14 and 16 are 
installed on the front panel 24 of case 18 and may be pointed in any 
direction to accommodate the physical layout of the room in which the 
lighting apparatus is placed. Also shown in the figure, are controls 22. 
Controls 22 are used to adjust various parameters of the lighting 
apparatus such as the sample and hold rate or flashing frequency of the 
lights. Finally, FIG. 2 shows a microphone 10 installed in the front panel 
of case 18. As described above, microphone be may be used for acoustic 
coupling of an input signal into the present lighting apparatus. 
FIG. 6 demonstrates an additional means of mounting the lighting apparatus 
in a case 18. In the embodiment shown in FIG. 6, it is anticipated that 
the apparatus would be used at a home setting. As shown in the figure 
colored lights 32, 34 and 36 may be mounted on the top of case 18. 
Controls 22 may be secured to the front of case 18 as shown. As discussed 
above, these controls would be used to vary control parameters in the 
lighting unit. In the embodiment shown in FIG. 6, it is desirable that the 
unit be constructed of a size to allow its placement atop a table, speaker 
or the like. 
FIGS. 3, 4, and 5 are detailed electrical schematic diagrams of the 
lighting apparatus of the present invention. In the preferred embodiment, 
and as shown in the figures, the lighting control apparatus comprises 
three filter channels. In each of the three channels, the functioning of 
the components is similar except for the frequencies which are passed in 
that channel. 
As shown in the FIG. 3, the signal source may be connected to the lighting 
apparatus by either of two methods. In the first instance, if the input 
signal is sound, it may be acoustically coupled to the lighting apparatus 
by means of connector CN2, which may connect to a microphone 10 (not 
shown) or other acoustically sensitive transducer. Alternatively, an input 
signal may be directly connected, electrically by means of connecter CN1. 
Choice between the input methods may be made by means of switch SW1. The 
input-signal then travels through diode D1 and capacitor C10 into parallel 
filter means comprising Op-Amps U3, U4, U5 and U7 shown in FIG. 4. Diode 
D1 and capacitor C10 serve to AC couple the input signal to the circuit 
thereby preventing any DC noise from reaching the circuit and guarding 
against transients. 
In the preferred embodiment, it is anticipated that the input signal would 
have a magnitude of approximately 30 v p--p. In that situation, no 
"pre-amplification" of the signal prior to filtering is needed. In the 
event that the input signal is weaker, a "preamplifier" consisting 
essentially of a broad bandwidth Op-Amp, may be inserted directly after 
capacitor C10. 
As explained earlier, Op-Amps U3, U4, U5 and U7 comprise a parallel filter 
network, operative to selectively pass frequency components within the 
operating range of each individual Op-Amp. In the preferred embodiment, 
Op-Amps U3, U4, U5 and U7 are 741 Op-Amps but may be any of a large number 
of linear amplifiers. As is well understood in the art, the operating 
range of each Op-Amp is determined by the external resistor and capacitor 
components. Op-Amp U3 comprises the low-pass filter which is operative to 
pass frequency components in the 20 to 400 Hz range. The frequency 
response characteristics of this Op-Amp are determined by resistors R1, R2 
and R3 in conjunction with the capacitors C1, C3 and variable capacitor 
C2. With the resistor and capacitor values as indicated in the schematic 
figure, Op-Amp U3 will pass frequencies in the 20 to 400 Hz range. 
Op-Amps U4 and U7 are configured to be a fourth-order, mid-band pass 
filter. The pass frequencies for Op-Amp U4 and U7 are determined by 
resistors R4-R6 and R24-R26 in conjunction with capacitors C4, C5 and C11, 
C12. With the values shown in the figure, the frequency range of 400 Hz to 
1,500 Hz is passed by the filter. Finally, Op-Amp U5 comprises the 
high-pass filter. With the values shown for R7, R8 and R9 in conjunction 
with C6 and C7, the filter will pass frequencies approximately 1,500 to 
20,000 Hz. 
After filtering, the high pass and low pass signals are further amplified 
by means of Op-Amps US and U6 respectively. These Op-Amps, in conjunction 
with their associated resistors, serve to further amplify the signals in 
the high and low pass bands. No additional filtering is done by the 
Op-Amps so the frequency characteristics of the signal remain the same. 
After filtering and amplification, the signals in all three frequency bands 
are next passed to the sample and hold circuits comprised of Op-Amps U1, 
and U9-U14 in conjunction with timer U2, and transistor switches Q1, Q2, 
and Q3. These three sample and hold circuits are operative to sample the 
analog output of the filter/amplifier circuits and provide a constant DC 
output over the holding period. As explained above and as is well 
understood in the art, the sample and hold period affects the circuit's 
ability to track the changing amplitude of the input signal. As previously 
mentioned, for a rapidly changing amplitude the sample rate must be 
correspondingly higher faster to accurately represent the signal. 
The sample and hold periods are determined by timer U2, capacitor C13 and 
variable resistors R33 and R34. In the preferred embodiment these controls 
are not user-adjustable but are set in the manufacturing process to give a 
sample and hold period which is sufficient to follow rapidly changing 
amplitudes in the input signal. The individual valves of R33, R34, and C13 
can be varied greatly. As is well understood in the art, R33 and R34 
determine the duty cycle of the U2 output while R33, R34 in conjunction 
with C13 determine the total period of the U2 output pulse. In the 
preferred embodiment, R33, R34 were adjusted to give a duty cycle of 
approximately 10%. The timing pulses from U2 are then inverted 
conventionally using Op-Amp U1 functioning as a Schmidt trigger. The 
individual valves of R35/R36 are to be equal. The inverted timing signal 
is then sent to sampling control switches Q1-Q3. Sampling control switches 
Q1-Q3 are N-channel JFET transistors configured to operate as ON/OFF 
switches. When transistors Q1-Q3 are "ON", buffered signals from unity 
gain buffers U9-U11 are allowed to flow through the transistors thereby 
charging capacitors C14- C16. The values to which the individual 
capacitors C14-C16 charge is representative of the amplitude of the 
sampled signal in that respective frequency band during the sampling 
period. This amplitude value is then transmitted to timers U15-U17 through 
buffers U12-U14. Buffers U9-U14 are preferably FET input Op-Amps 
configured as emitter-follower amplifiers of unity gain. Once the signal 
in each channel is sampled, it is converted into a square wave pulse train 
by timers U15-U17. The timing characteristics of this square wave define 
the enabling period of the flashing lights. 
Timers U15-U17 translate the sampled voltage from C14-C16 through buffers 
U12-U14 into square wave, enabling pulses, the periods of which vary in 
proportion to the input sampled voltage. As is well understood in the art, 
the range over which this period varies individually in each filter 
channel is determined by resistors R27-R32 and capacitors C17-C19. In the 
preferred embodiment, the range of variation of the enabling pulse period 
is approximately 0 to 1 seconds depending on the amplitude of the sampled 
signal. The square wave enabling pulses from U15-U17 are transmitted to 
PNP transistors Q4-Q6 which in turn control the flashing of lamps L1-L3. 
Transistors Q4-Q6 function as switches to control the flashing of lamps 
L1-L3. When Q4-Q6 are switched "ON" by timers U15-U17, silicon controlled 
rectifiers SCR1-SCR3 are turned "OFF" and do not conduct. When transistor 
switches Q4-Q6 are switched "OFF", SCR1-SCR3 are allowed to conduct. Thus, 
the switching of SCR1-SCR3 serves an "enabling" function and controls the 
period during which lamps L1-L3 flash at their predetermined rate. 
The rate at which lamps L1-L3 flash is determined by the values of 
resistors R33-R35 and capacitors C20-C22. In the preferred embodiment with 
the values shown the lights will flash at a rate of approximately 10 Hz. 
This rate may be adjusted by changing the values of the resistors and 
capacitors. It has been found that the flash rate must be less than 18 Hz 
to allow ON-OFF transitions to be appreciated. 
As mentioned above, the enabling periods are determined by the values of 
the external resistors and capacitors on timer circuits U15, U16 and U17 
in conjunction with the input signal amplitude. For example, in the 
mid-band pass filter channel, resistors R29 and R30 in conjunction with 
C18 determine the enabling periods for timer U16. In the preferred 
embodiment, timer circuits U15, and U17 give an enabling flash period of 
approximately 0 to 1 seconds. 
The voltage doubler 80 delivers a dc voltage of 340 volts to 3 parallel 
connected xenon lights LP1, LP2, and LP3 whose required anode-cathode 
voltage is 300-400 v (such as Tec-West models). 
An alternative to the doubler would be a 2-output transformer (one step-up 
and one step-down), and appropriate rectifiers. 
Identical triggering configurations consist of identical trigger coils L1, 
L2, and L3 delivering negative voltage spikes of -6 Kv/0.4 watt at the 
trigger electrodes; and of identical capacitors C20, C21, C22 delivering 
standard spikes of approximately -200 v to coils primary side. 
The 3 SCRs SCR1, SCR2, SCR3 deliver the above voltage spikes when fired. 
The firing occurs automatically when the neon lamps NE1, NE2, NE3 are 
charged to the firing voltage. After firing, the SCRs recover 
automatically with time constant determined, respectively, by resistors 
R33-R35 and capacitors C20, C21, C22. The frequency of the SCR firing and, 
thus, that of tube flashing can be adjusted with the help of variable 
resistors R33-R35. At a flash frequency of 25 Hz, the lights only flicker 
slightly. 
The bipolar or FET transistors Q4, Q5, Q6, when turned on, disable the SCRs 
by putting the gates at ground potential, and, when turned off, enable the 
SCRs. The time interval during which the SCRs are enabled is adjustable 
from 0.1 to 1 sec., using timers U15-U17 described below. 
Another option for firing the SCRs is to eliminate the neon lamps and 
deliver the voltage spikes directly to the gates of SCRs and using other 
means to turn off the SCR. Additionally, the SCRs may be replaced with any 
switching device capable of operating as an "ON/OFF" switch. 
The transistors Q4, Q5, Q6 are turned on and off by timers U15, U16, U17 
with adjustable intervals of high and low levels. The frequency of the 
timers is adjusted by the output signals from the sample-and-hold circuits 
Q1, Q2 and Q3. When, during a time interval, the sample-and-hold output is 
below a certain adjustable level, the frequency of the timers drops to 
zero, disabling the SCRs and the tubes for that time interval. 
As described above, each of these three circuits consists of 2 buffer 
amplifiers U9-U14, one n-JFET Q1-Q3, and one holding capacitor C14-C16. 
Other equipment, such as isolating resistances, droop compensating 
capacitors, reset FETS and limiting diodes and others are optional. As is 
well understood in the art, when an n-JFET is on, the input signal passes 
through to the capacitor thereby charging the capacitor. This is the 
sampling time. When the FET is off, the capacitor is practically isolated 
and retains its charge. This is the holding time. Optionally, the circuits 
can be used as peak detectors. 
The ratio of sample time to holding time is controlled by clocking the FETS 
Q1-Q3 from the clock U2, the frequency and the duty cycle of which are 
adjustable by means of R33, R34, and C13. 
Thus, lights L1, L2 and L3 flash at a preset frequency during the enabling 
period which is in direct proportion to the amplitude of the sampled input 
signal corresponding to the frequency band of the channel to which the 
light is connected. As mentioned above, if the flash frequency is suitably 
adjusted, relative to the enabling period, the flash rate of the light 
will be effectively determined by the amplitude of the sampled signal. 
In the preferred embodiment, the lights L1-L3 are 4-10 watt, 250-400 V 
alarming lamps. Additionally, in the preferred embodiment, each of the 
lamps attached to each filter channel will be of a different color. 
Obviously the colors chosen are to be determined by individual preference 
and may be changed as desired. Still further it should be noted that 
although the description of the preferred embodiment has centered around 
use of the lighting apparatus in the context of visually representing 
different frequency components of a sound input, the same circuitry may be 
used in other contexts such as pressure, temperature or the like. Any 
analog signal may be converted to a variable frequency and used to drive 
the lighting apparatus of the present invention in the same manner as with 
the preferred sound input. Additionally, and as mentioned above, the 
number of frequency channels into which the input signal is separated may 
vary from one to many depending on the unique lighting effect desired. 
More importantly the implementation of the electric pulsing means may be 
altered to accommodate a different visual effect. For example, and as 
described above the sample-and-hold circuit could be used to control the 
flashing frequency of the light itself. In that embodiment, the flash rate 
of the light might be set to be proportional to the amplitude of the 
signal in that channel. 
Therefore, it is to be understood that the above description is intended in 
no way to limit the scope of protection of the claims and is 
representative of only one of the several possible embodiments of the 
invention. 
Thus there has been shown and described an invention which accomplishes at 
least all of the stated objectives.