US3550497A - Color display for sound reproducing systems - Google Patents

Description

United [72} Inventor Gregory S. Marsh 90 Tidewater Road Henlopen Acres, Rehoboth, Del. 19971 [211 App]. No. 763,027 [22] Filed Sept. 26, 1968 [451 Patented Dec. 29. I970 [54] COLOR DISPLAY FOR SOUND REPRODUCING SYSTEMS 4 Claims, 1 Drawing Fig.

[52] U.S. Cl 84/464 [51] lnt.Cl A63j 17/00 [50] Field of Search 84/464 [56] References Cited UNITED STATES PATENTS 3,228,278 l/l966 Wortman 84/464 2,806,953 9/1957 Krauss 84/464 3038061 6/1962 OReilly 84/464 3,474,774 10/1969 Johnson et al. 84/464 OTHER REFERENCES Blechman, F Transistor-Photocell Color Organ," Electronics World, Vol. 72, No. l, Ziff-Davis Publishing Co.. New York, July. 1964, pp. 41-43.

Primary Examiner-Richard B. Wilkinson Assistant Examiner-Lawrence R. Franklin A!r0rne vBurns. Doane, Benedict, Swecker and Mathis ABSTRACT: A variable color display for sound which is responsive to the combination of the frequency and amplitude of the audio frequency signal. The display includes a plurality of signal channels, each containing a series connected capacitor and neon tube with each capacitor having different capacitive values, connected in parallel whereby the neon tubes turn on and off at different times and produce light outputs that may be of different intensities in response to the same audio signal. Photoresistors located with each neon tube control the voltage supplied to different ones of a plurality of differently colored lamps. The lamps of different colors are thus selectively energized to produce a color display which has a unique relation to audio frequency signals, and particularly to music.

l 3e L. W 2 24 30 F- as PATENTED DEEZSISYB 5 9 INVENTOR. GREGORY 5, MAR 5H BY 16mm M fimm m w ATTORNEYS COLOR DISPLAY FOR SOUND REPRODUCING SYSTEMS BACKGROUND OF THE INVENTION The invention relates to a variable color display in response to audio frequency signals, and more particularly to a display where the individual colors are responsive to the combination of frequency and amplitude of audio input signals.

Variable color displays have been used to produce a psychedelic effect during musical performances. These prior displays have included a plurality of differently colored lamps which flash on and off during the musical performance, and in some cases, the displays have operated on a predetermined program by utilizing commutator switches to selectively actuate the lamps. The effect of such systems is too orderly and does not bear any correspondence to the music being played.

Other systems have overcome this problem by making the energization of the lamps responsive to the music itself. This has been accomplished by providing a plurality of frequency selective paths including narrow band filters so that lamps of a particular color are energized in response to a particular frequency of sound. These systems, however, incorporate complex circuits which include expensive elements thereby making such systems relatively expensive. In addition, these systems produce a somewhat refined effect due to the precise selectivity of their frequency responsive paths.

It is the major object of this invention to provide a variable color display for sound which can be produced with very inexpensive circuit components and which produces a unique and intriguing color pattern in relation to music because of being responsive to an unusual combination of both frequency and of amplitude.

DETAILED DESCRIPTION Referring now to the drawing, which illustrates a schematic of a circuit embodying the present invention, a pair of terminals 2 and 4 are adapted to be connected to a source of audio frequency signals (not shown) such as the output of an amplifier connected to a microphone, radio, tape or record player, or the like. Terminals 2 and 4 are connected through a variable resistance such as potentiometer 6 having a movable tap .8, to the primary winding, which may for example have 8 ohms resistance, of a magnetic core transformer 10.

The secondary winding of transformer 10 may have a resistance of between 5 K and K ohms and hence produce an audio frequency signal voltage which is somewhat higher than the voltage customarily supplied to loudspeakers.

Connected across the terminals of the secondary winding of transformer 10 are three signal channels, each containing a series circuit consisting of a capacitor 12, 14 or 16, and a neon tube 24, 26 or 28, respectively. Neon tubes 24, 26 and 28 are mounted in close proximity tophotoresistors 30, 32 and 34, respectively, which in turn are connected in series with lamps 36, 38 and 40. Lamps 36, 38 and 40 are of three different colors, such as red, amber and blue, and are connected to be energized from power, such as 1 17 volts AC at terminals 42 and 44.

Neon lamps 24, 26 and 28 are of the type where the gas ionizes at a predetermined voltage and where the ionization extinguishes at a somewhat lower voltage. A suitable lamp is commercially available as an NE-2 neon lamp. This lamp is rated to operate with 117 volts, but will become conductive and produce light with an applied voltage somewhat in excess of about 60 volts. When the applied alternating voltage is less than about 50 volts, ionization is lost and production of light ceases.

Photoresistors 30, 32 and 34 are mounted in light- tight housings 18, and 22 with their respective neon lamps 24, 26 and 28. The photoresistor may be secured against the envelope wall of the neon tube by a suitable tape, or adhesive, or the assembly may be potted in a suitable plastic.

Lamps 36, 38 and 40 may be of conventional type form such as a C-7-/ or D-33 available from General Electric Company.

In the operation of the foregoing circuit, audio frequency signals on terminals 2 and 4 are fed through the variable resistor 6 to the primary winding of transformer 10. By adjusting the movable tap or resistor 6, the amplitude of the signal output from the secondary winding of transformer 10 may be varied to thus obtain the desired response of the display to the normal level of the incoming audio frequency signals.

The signal voltage is stepped up in the transformer 10 and applied simultaneously to all three neon lamps 24, 26 and 28 through capacitors l2, l4 and 16, respectively. The relative impedance provided by capacitors l2, l4 and 16 for a signal at any particular frequency in the audio frequency signal varies in accord with their different capacitive values. Typical values of capacitance which may be used are 0.05, 0.036 and 0.018 ,uf. The smallest capacitor presents the largest impedance, and hence its associated neon tube will not become a source of light until after both of the other neon tubes have become light sources. When the amplitude of a particular signal frequency exceeds a certain value, all three neon tubes become light sources; and the neon tubes associated with the capacitor having the lowest capacitive value will be the first to become extinguished as the amplitude of the audio signal decreases, such as during a pause in speech or in music.

From the foregoing, it is evident that a loud audio signal, even at a relatively low frequency, can cause two or all of the neon tubes to become light sources. At a higher frequency, the same result can be achieved with a corresponding decrease in audio level. The intensity of the display light from lamps 36, 38 and 40 is controlled by the amount of resistance offered by photoresistors 30, 32 and 34. Hence, with an increase of light output from a neon tube due to an increase in current flow resulting from audio frequency signals of higher amplitude, there is a corresponding increase in the intensity of the output from lamps 36, 38 and 40.

By the appropriate adjustment of the variable resistor 6 after the desired loudness of the sound fromspeaker 46 has been selected, it is possible to obtain a variable color display where both the number of different colors that are displayed and the intensity of each displayed color increases as the loudness and the pitch of the music increase.

Obviously, four or more signal channels can be used where display lamps of four or more colors are desired. Also, where stereo sound systems are employed, two units each indentical to the unit described above may be provided, with a different unit for each channel of the stereo system. Each of lamps 36, 38 and 40 may be replaced by two more lamps of the same color where a large area display unit is desired. A translucent plate over the lamps to minimize the apparent point source of each lamp is also advantageous.

From the foregoing, it is evident that by the present invention, there is provided a variable color light display responsive to audio frequency signals where the number of components required is minimized, and all the components are commercially available at relatively low cost when compared with similar systems shown in the prior art. In accordance with the invention, each of the series circuits connected to the secon dary winding of transformer 10 includes essentially an ionizable gas-filled glow tube and a capacitor, and therefore does not require components constituting an amplifier stage.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Iclaim:

1. Apparatus for producing a variable color visual display of an audio frequency signal comprising:

a source of audio frequency signals;

a first plurality of series circuits each including essentially an ionizable gas-filled glow tube and a capacitor, at least two of said capacitors having different values of capacitance, each of said circuits being connected to said source of audio frequency signals; and

a secondplurality of series circuits each including a photoresistor and a lamp connected to be energized from a power source, at least two of said lamps having a different color and each of said photoresistors being illuminated by one of said glow tubes whereby said lamps of different colors are energized at different times in response to the same frequency signals.

2. Apparatus as defined in claim 1 wherein said glow tubes are neon gas tubes and the gas is ionized when applied voltage is in excess of about 60 volts and ionization is extinguished when the applied voltage is less than about 50 volts.

3. Apparatus as set forth in claim 1 further including a transformer having a primary winding connected to receive said audio frequency signals, and a secondary winding having output terminals, said first plurality of series circuits being connected to terminals on said secondary winding, and a sensitivity control means for varying the responsiveness of said display to the amplitude of said audio frequency signals.

4. Apparatus as set forth in claim 3 wherein said sensitivity control means consists solely of a-single variable resistor connected in series circuit arrangement with the primary of said transformer.

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