Device and method for optical tone generation

An optical tone generator comprises sensing means responsive to light of different respective colors for selectively producing respective output signals corresponding to such respective colors, and a tone generator responsive to the sensing means for emitting a tone corresponding to the signal produced by the sensing means. In a preferred embodiment, fiber optic light conduits are disposed within an elongated baton for manual translation along a line of discretely changing colored strips to produce tones corresponding to the various colors. This device is particularly advantageous for teaching musical composition because it permits a child to vary pitch, duration and tempo by readily perceived variations in color, length and speed, respectively.

BACKGROUND OF THE INVENTION 
This invention relates to a device and method for optical tone generation. 
More specifically, it relates to a device and method for picking up light 
reflected from a colored control surface and emitting a tone coded in 
pitch to the color of the surface. 
The device is particularly useful as an educational toy for children. In 
conjunction with the invention, children can compose their own musical 
compositions using crayons or colored pencils and play their compositions 
using the tone generator of the invention. 
While a child can readily exercise his creative abilities in the visual 
arts, there is no simple means whereby a yound child can exercise and 
develop his creative abilities in the area of musical composition. There 
are a host of media through which he can draw, paint, model and sculpt. 
But if he seeks to reproducibly compose an aural composition, the child is 
immediately confronted with a traditional system of musical notation which 
is complex even for many adults. Indeed teaching devices have been 
designed to teach the child merely the names of the components of this 
notation system. See U.S. Pat. No. 2,447,213 issued to E. F. Sledge. 
While devices exist for reading printed sheet music, these devices are too 
sophisticated and too automatic to serve as useful teaching aids for small 
children. U.S. Pat. No. 3,424,851 issued to D. M. Weitzner, for example, 
discloses a music reading and sounding device for which a composer will 
transcribe into a series of opaque elements on translucent paper a musical 
composition written in conventional musical notation. The thus-encoded 
translucent paper is then fed into the automatic playing device wherein 
the opaque elements are detected by their interruption of light paths 
through the translucent paper and appropriate prerecorded tones are 
selectively accessed and replayed. Tempo is varied by a rotatable knob. 
While the Weitzner device may have merit for the adult composer, for the 
child it still interposes a level of abstraction between him and 
reproducible composition. At the very least, the user of the Weitzner 
device must understand the abstract code whereby conventionally denoted 
tones are encoded onto the translucent sheet. 
Accordingly, a simpler device using parameters more readily perceived by 
the child is required in an effective teaching device. 
SUMMARY OF THE INVENTION 
In accordance with the invention, an optical tone generator comprises 
sensing means responsive to light of different respective colors for 
selectively producing respective output signals corresponding to such 
respective colors, and a tone generator responsive to the sensing means 
for emitting a tone corresponding to the signal produced by the sensing 
means. In this manner, a sequence of colors selected from a predetermined 
set of colors may be scanned and each of the colors will cause the tone 
generator to produce an audible tone corresponding to that color. The 
colors may be pre-printed on a sheet of paper or other surface (herein 
called a control surface), or they may be provided in the form of crayons 
or paints for use in composing music to be played by the tone generator. 
The tone generator preferably includes one or more light pipes, or fiber 
optics for sensing the color of the control surface to produce the 
corresponding pitch tone and, if desired, to transmit light to the control 
surface. 
In a preferred embodiment, the tone generator includes a light source for 
illuminating a colored control surface and a plurality of light conduits 
for transmitting light of selected colors to respective photosensors. The 
photosensor outputs, in turn, are coupled to tone generation means by 
switching circuitry so that the tone emitted is coded in pitch to the 
color of the control surface. The light conduits are preferably fiber 
optics disposed within an elongated baton for manual translation along a 
line of discretely changing colored strips. This device is particularly 
advantageous for teaching musical composition because it permits a child 
to vary pitch, duration and tempo by readily perceived variations in 
color, length and speed, respectively.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to the drawings, FIG. 1 is a block diagram schematically 
illustrating an optical tone generating device for generating a tone coded 
in pitch to the color of a colored control surface 9. The device comprises 
a light source such as a three volt incandescent lamp 10 for directing 
light onto control surface 9, through for example, one or more light 
source fiber optics 11. A plurality of color-selective light pick-up 
elements, such as filtered fiber optics 12, 13 and 14 having red, green 
and blue filters 15, 16 and 17, respectively, are provided for picking up 
light of different respective colors from source 10 reflected from control 
surface 9 and directing such light to a plurality of respective 
photosensors, such as phototransistors 18, 19 and 20. 
The light source fiber optic 11 and the pick-up fiber optics 12, 13 and 14 
are preferably disposed in an elongated generally cylindrical member 21 
resembling a baton, or wand, with a tip having the output ends of fiber 
optic 11 and the filtered input ends of optics 12, 13 and 14 positioned as 
shown in FIG. 2 for reading the colored control surface as the tip is 
moved thereacross. 
Referring back to FIG. 1, the photosensors produce respective electrical 
output signals indicative of the presence or absence of light of the 
different respective colors, i.e. if colored surface 9 reflects red light, 
phototransistor 18 gives an electrical output signal; if green light, 
phototransistor 19 produces an output signal; and if blue light, 20 
produces an output. Spurious outputs from minimal intensities of light can 
be prevented by providing potentiometer sensitivity controls 22 or 
threshold devices to the photosensor outputs. 
The outputs of the photosensors are applied to a multiple-frequency tone 
generator, generally denoted 23, for selectively generating one of a 
plurality of different frequency tones dependent upon the combination of 
different colors detected by the photosensors. In a preferred embodiment, 
the generator comprises a switching circuit 24, such as a binary coded 
decimal (BCD) to decimal convertor, a switchable multiple-frequency audio 
frequency oscillator 25, an amplifier 26 (if needed) and a loudspeaker 27. 
In response to the outputs from the photosensors, the switching circuit 24 
selectively activates the switchable multiple-frequency oscillator to 
generate a particular frequency uniquely in accordance with the 
combination of output signals from the photosensors. The oscillator output 
signal is then amplified by amplifier 26 to produce a corresponding tone 
from loudspeaker 27. 
In one embodiment, it is contemplated that the eight possible combinations 
of the colors red, green and blue (including the absence of any of them) 
on the control surface will be used to trigger tones corresponding in 
pitch to seven corresponding notes on a musical scale. An exemplary 
correlation between color combinations and tonal frequencies is set forth 
in Table 1 below, there R, B and G designate detectable colors of red, 
blue and green in the light reflected from control surface 9, and the 
corresponding frequencies are the ascending notes A (below middle C) 
through A, in the key of C major. 
______________________________________ 
Color Combination 
Tonal Frequency (Hertz) 
______________________________________ 
R 440.00 
B 493.88 
G 523.25 
R + G 587.33 
G + B 659.26 
R + B 698.46 
R + B + G 783.99 
None of R, B and G 
880.00 
______________________________________ 
By using additional primary colors, the number of different tones generated 
may be increased; for example a fourth primary color doubles the range of 
tones that may be generated to two octaves. 
FIG. 3 shows the circuit diagram of one form of switchable, 
multiple-frequency audio oscillator for generating musical notes in 
accordance with the above tabulated color combinations. Since only seven 
outputs are available on the particular encoder shown, the 880 hertz tone 
is omitted. The individual circuit components are all standard items and 
may have the values of resistance and capacitance set forth in the 
drawing. The CD4051AE chip is a binary -to- decimal convertor that emits a 
particular output on one of the outputs numbered 1-7, corresponding to 
each combination of inputs A, B and C from phototransistors 18, 19 and 20. 
The resistance value thus inserted in series with terminal 6 of the 555 
timer determines the frequency of the timer output signal, which drives 
speaker 27. 
The particular components shown are available in highly miniaturized form, 
but any standard electronic components suitable for the particular 
application may be used. 
In the preferred method of using the invention, it is contemplated that the 
user will be provided with a plurality of colored markers, such as 
crayons, for marking a sheet with a plurality of primary colors, such as 
red, green and blue, and additive color combinations thereof such as 
yellow, blue-green, violet, white (the sum of all three primaries) and 
black (the absence of all of the three primaries). The user will use these 
colored markers to compose a musical composition by marking strips of 
different colors and different lengths across a sheet of paper, thus 
creating a colored control surface. The color of each strip determines the 
pitch of the note and the length of the strip determines its duration. 
The composition thus created is played by moving the light source and 
light-selective pick-up along the colored strips of the control surface, 
as by moving the tip of baton 21 over the strip. Depending upon the color 
of the control surface, one or more photosensors are activated, in turn 
activating the multiple-frequency tone generator to produce a musical tone 
coded in pitch to the color of the control surface. Tempo is controlled by 
the speed at which the pick-up is moved across the control surface. 
The provision of additional manual switches connected to change the 
resistors R.sub.1 -R.sub.7 shown in FIG. 3 may be used to convert from a 
major to a minor mode, or to modulate to a different key by changing the 
pitch of the output tones. 
The control surface may be printed in half-tone with the primary colors 
printed separately to form the combined colors in accordance with 
conventional printing methods. Where crayons are employed, the combination 
colors are preferably formed of the two or more primary colors that make 
them up; e.g. a blue-green crayon would be formed of blue and green 
pigments. Preferably, for instructional purposes, the set of such crayons 
is ordered, and the resistors R.sub.1 -R.sub.7 are correspondingly 
ordered, such that the darkest color crayon corresponds to the lowest 
frequency tone generated and successively lighter colors correspond to 
tones of successively higher pitch. 
It will be readily appreciated that this device and method are particularly 
advantageous for teaching musical composition to children because pitch, 
duration and tempo are controlled by readily perceived variations in 
color, length and speed, respectively. 
While the invention has been described in connection with only a small 
number of specific embodiments, it is to be understood that these are 
merely illustrative of many other specific embodiments which can also 
utilize the principles of the invention. Numerous and varied devices can 
be made by those skilled in the art without departing from the spirit and 
scope of the present invention, which is defined in accordance with the 
following claims.