Four-quadrant Indicator Employing Moire Effect

Abstract

Display apparatus for indicating motion and displacement of a control lever movable about one end thereof through various positions within a spherical sector of radius substantially coextensive with the lever comprises a first regular pattern formed on a transparent surface positionable by the control lever, and a second regular pattern formed on a surface beneath the positionable surface. By employing equally spaced lines in each pattern, each position of the control lever results in creation of unique moire fringes which are set into motion whenever the control lever is moved.

Description

INTRODUCTION

This invention relates to visual displays, and more particularly to indicators for displaying the effects of moving a control lever about one end thereof through various positions within a substantially spherical sector of radius coextensive with the lever.

The purpose of employing four-channel stereo playback systems is to reproduce for the listener the effect of hearing music as he might if he were seated at a live performance in a concert hall, wherein he hears sound emanating directly from the stage and reverberating from the surfaces within the hall. As the name implies, four separate channels of sound are involved, with each channel representing the sound at a particular location at the recording site. These channels are individually coupled through the system to four separate loudspeaker enclosures, two of which are preferably placed in front of the listener on either side thereof and reproduce the sound recorded at the left and right sides of the stage, and the other two of which are preferably placed behind the listener on either side thereof and reproduce the complex sound at the rear of the hall made up of natural reverberations from the surfaces within the room containing the recording site plus sound emanating from the stage itself.

In order to provide the listener with reproduced sound that seemingly is how he would have heard it if present in the concert hall when and where it was produced, it is necessary to balance the system so that volume of sound produced by the system is optimized. This balance obtains when the volume of sound produced by any one loudspeaker enclosure is relatively the same, with respect to that produced by each of the other three loudspeaker enclosures, as the volume of sound recorded at the recording location corresponding to that one enclosure is with respect to the volume of sound recorded at each of the other three recording locations, respectively. One type of control for achieving such balance has required use of three separate potentiometers. Typically, in this type of control, one potentiometer balances the right front and left front loudspeaker enclosures with respect to each other, the second balances the left rear and right rear loudspeaker enclosures with respect to each other, and the third balances the combined front loudspeaker enclosures with respect to the combined rear loudspeaker enclosures. While such controls are entirely adequate, they require individual manipulation of three separate knobs.

To reduce the manipulations required to achieve balance among separate loudspeaker enclosures in four-channel stereo playback systems, a so-called joystick control has been employed. This control operates in a manner similar to that of the control stick employed in aircraft to achieve changes in pitch and roll; that is, movement of the joystick through any geometric plane oriented along a given direction controls audio output of the pair of front loudspeaker enclosures in relation to the pair of rear loudspeaker enclosures, and movement of the joystick through any geometric plane oriented along a direction perpendicular to the given direction controls audio output of the pair of loudspeaker enclosures on the left in relation to the pair of loudspeaker enclosures on the right. Movement of the joystick in any direction other than through the aforementioned geometric planes causes interaction among the audio outputs of the four loudspeaker enclosures with the resultant effect being that a complete rebalancing of the audio outputs produced by all four loudspeaker enclosures occurs.

Small displacements of the joystick control, however, may not have a readily noticeable effect on the audio outputs of the loudspeaker enclosures, due, for example, to the degree of aural sensitivity on the part of the listener (especially if the displacement is made at the instant when the musical instruments in one section of the orchestral music source substantially supplant the musical instruments in another section). In such case, the listener may not be sure that he did, in fact, reposition the joystick. Accordingly, one object of the invention is to provide an indicator on which displacement of the joystick by even a small amount may be visually detected.

Another object of the invention is to provide a device which presents a moving visual display during movement of a joystick.

Another object is to provide esthetic visual effects to accompany each movement of a joystick and a different esthetic visual pattern to accompany each separate respective position of the joystick.

Another object is to provide apparatus employing the moire effect to designate the general direction in which a joystick is moved.

Briefly, in accordance with a preferred embodiment of the invention, a visual display for indicating motion and dsiplacement of a control lever movable about one end thereof through various positions within a spherical sector of radius substantially coextensive with the lever is provided. The display comprises a first regular pattern formed on a transparent surface which is positionable by movement of the lever, and a second regular pattern formed on a surface situated beneath the transparent surface such that the second regular pattern is visible through the transparent surface. The first and second patterns are thus superimposed on each other so as to form moire fringes.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side view of the indicator of the present invention;

FIG. 2 is a plan view of a typical stationary pattern employed in the indicator of the invention;

FIG. 3 is a plan view of a movable pattern employed in the indicator of the present invention;

FIG. 4 is a plan view of a typical viewing window employed in the indicator of the invention;

FIG. 5 is a top view of the indicator of the present invention, with the joystick in its center position; and

FIG. 6 is a top view of the indicator of the present invention, with the joystick offset from its center position.

DESCRIPTION OF TYPICAL EMBODIMENTS

In FIG. 1, the indicator of the present invention is illustrated as comprising an escutcheon 10 and a joystick 11 having a manually operable portion 9 thereof, which swivels at one end about a ball and socket joint made up of ball 12 and socket 13. Joystick 11 is thereby movable through various positions within a spherical sector of radius substantially coextensive with joystick 11. A rod 14, affixed to ball 12, penetrates gimbals 15 and 16 so as to move the gimbals whenever ball 12 is repositioned by movement of joystick 11.

A group of four potentiometers, two of which, 17 and 18, are illustrated, are mounted on each side of a four-sided chassis 20, shown partially cut away, such that each potentiometer shaft, such as shaft 21, is affixed to one end of a gimbal, respectively. Thus, potentiometer shaft 21 is affixed to one end of gimbal 16 while potentiometer shaft 22 is affixed to one end of gimbal 15, and movement of joystick 11 is conveniently converted into rotation of the potentiometer shafts. Each potentiometer is electrically connected to control amplitude of audio output from a separate loudspeaker enclosure, respectively.

Affixed to chassis 20 is an apertured plate 30 on which, as shown in FIG. 2, a regular, distinctive pattern is formed by any of a number of conventional ways, such as printing, engraving, overlaying, etc. This pattern preferably comprises a plurality of equidistantly spaced lines so as to constitute a periodic strucure, formed on the upper surface of plate 30. Conveniently, the pattern may be made up of four sets of arcs of concentric circles, each set of arcs, respectively, being centered about a separate corner of plate 30 where plate 30 is formed in the shape of a four-sided polygon, such as a square. Joystick 11, as shown in FIG. 1, passes through the aperture in plate 30, leaving the joystick free to swivel within the aperture.

Positioned atop plate 30, as shown in FIG. 1, is a transparent plate 31 having a sloped collar 32 with a beveled edge 33 facing joystick 11. Plate 31 is slidably displaceable through 360.degree. within the plane of the plate. Joystick 11, when moved, bears against collar 32 so as to shift the position of plate 31 in the direction of movement of the joystick. Any portion of beveled edge 33 cooperates with its diametrically opposite portion of the inner surface of collar 32 to allow joystick 11, when thrown fully to one side, as illustrated by either dotted position of joystick 11, to minimize lost motion between the joystick and plate 31 when the joystick is returned from its maximum offcenter position.

As illustrated in FIG. 3, plate 31, typically in the shape of a four-sided polygon, such as a square, contains a regular, distinctive pattern made up of a plurality of equally spaced opaque lines so as to constitute a periodic structure. Conveniently, the line pattern is formed of a plurality of concentric circles on the lower surface of plate 31, with arcs of concentric circles extending outward to the corners of the plate. The circles are centered about the center of the aperture defined by collar 32. Spacing of the lines in the pattern on plate 31 is made equal to that in the pattern on plate 30, in order to produce well-defined, prominent moire fringes by virtue of superimposition of the patterns on plates 31 and 30. As with plate 30, the line pattern produced in plate 31 may be formed by any of a number of conventional methods, such as printing, engraving, overlaying, etc. An additional pattern 34, comprising an arrangement of dots and radially-directed lines situated in a circle, is preferably formed by a similar process on the upper surface of plate 31 and centered about the center of the aperture therein, giving added visual emphasis to the position of the joystick on the indicator.

Situated atop plate 31, as shown in FIG. 1, a fixedly-mounted, transparent viewing plate 35 containging indica, such as illustrated in FIG. 4, to designate the effect of movement of the joystick in any given direction. These indica, which show the user what loudspeaker enclosure or enclosures of the four-channel stereo system are being emphasized and what enclosures are being deemphasized, generally signify four quadrants within which sound is emitted, permitting the listener to balance the sound heard from these four quadrants as he desires. The indicia may be formed by any of the aforementioned methods for producing patterns on plates 30 and 31 of FIG. 1, on the lower surface of plate 35 in order to prevent abrasion of the pattern through normal usage of the indicator. An opaque border 36 around plate 35 prevents the edges of plate 31 from being visible to the user even when joystick 11 is at its maximum off-center position.

FIGS. 5 and 6 are illustrations of typical moire fringes presented visually to the user. In the example of FIG. 5, the joystick is centered, so that circular scale 34 of dots and radial lines on the upper surface of plate 31 is centered about the joystick and with respect to the indicia on the viewing plate. However, should the joystick be moved from its central position, the moire fringe pattern is altered and circular scale 34 moves off-center with respect to the indicia on the viewing plate, in the direction of displacement of the joystick. This condition is illustrated in FIG. 6. During motion of the joystick from its condition illustrated in FIG. 5 to its condition illustrated in FIG. 6, the moire fringe pattern is altered, and a visual illusion of much movement is presented to the user of the indicator, even if the joystick motion is slow and even if it is produced by but a small displacement of the joystick. Hence, the user visually receives information which unmistakeably tells him that he has moved the joystick. Additionally, by use in the indicator of the patterns illustrated in FIGS. 2 and 3, movement of the joystick in any given direction causes the moire fringes to appear to widen or open in the direction toward which the joystick is being moved, and to narrow or close behind the joystick, thereby providing to the user an indication of the quadrant toward which the joystick is being moved. To further enhance the visual effects, plate 30 of FIG. 1 may be made transparent, and a light source employed beneath plate 30, so that the opaque lines forming the patterns on plates 30 and 31 produce directly illuminated moire effects.

The foregoing describes an indicator on which displacement of a joystick by even a small amount may be visually detected. The device provides esthetic dynamic visual effects to accompany each movement of the joystick and different esthetic static visual patterns to accompany each separate respective position of the joystick. The moire effect is employed to produce fringes designating the general direction in which the joystick is moved.

While only certain preferred features of the invention have been shown by way of illustration, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

I claim:

1. Display apparatus for indicating motion and displacement of a control lever movable about one end thereof through various positions within a spherical sector of radius substantially coextensive with said lever, said apparatus comprising:

a first regular pattern formed on a transparent surface, said transparent surface being engageable with said lever and displaceable through 360.degree. by movement of said lever;

a second regular pattern formed on a surface situated beneath said transparent surface such that the second regular pattern is visible through the transparent surface, said first and second patterns being superimposed on each other so as to form moire fringes; and

means retaining both of said surfaces to limit maximum displacement of said first pattern relative to said second pattern. 2. The display apparatus of claim 1 wherein said transparent surface contains an aperture through which said lever passes to permit said transparent surface to be slidably displaced atop the surface on which said second pattern is formed, in

accordance with the positioning of said lever. 3. The display apparatus of claim 2 wherein said aperture is surrounded by a collar, said collar being

in contact with said lever at least when said lever is being moved. 4. The display apparatus of claim 1 wherein the surface on which said second

pattern is formed is transparent. 5. The display apparatus of claim 1

wherein the surface on which said second pattern is formed is opaque. 6. The display apparatus of claim 2 wherein each of said first and second patterns comprises substantially equally spaced lines, each of said lines

representing at least an arc of a circle. 7. The display apparatus of claim 6 wherein lines in said first pattern form a plurality of concentric circles and lines in said second pattern form four sets of arcs of concentric circles, each set of arcs, respectively, in said second pattern being centered about a separate corner of a four-sided polygon,

respectively, containing said second pattern. 8. A visual display for indicating motion and displacement of a lever movable about one end thereof, said lever being displaceable through a spherical sector of radius substantially coextensive with said lever, said display comprising:

a first pattern of equally spaced lines being formed of opaque material separated by regions transparent to light, said lever being contiguous to said first pattern such that said first pattern is displaceable through 360.degree. by movement of said lever;

a second pattern of equally spaced lines being formed of oapque material separated by regions transparent to light, said first and second patterns being superimposed on each other to form moire fringes; and

means retaining both of said patterns to limit maximum displacement of said

first pattern relative to said second pattern. 9. The visual display of claim 1 whrein said first pattern includes an aperture through which said lever passes to permit said first pattern to be slidably displaced atop

said second pattern in accordance with positioning of said lever. 10. The visual display of claim 9 wherein the line spacing of said first pattern equals the line spacing of said second pattern, each of said lines being

at least an arc of a circle. 11. The visual display of claim 10 wherein lines in said first pattern form a plurality of concentric circles and lines in said second pattern form four sets of arcs of concentric circles, each set of arcs, respectively, being centered about a separate corner of a four-sided polygon, respectively, containing said second pattern.