US 3701963 A
An improved control device for use in volume adjustment of a multi-speaker sound system is provided with means for simultaneously adjusting the volume of some or all of the speakers in the system. A plurality of variable resistors are mounted on an insulating substrate, the effective resistance of each resistor being adjustable by sliding contact means.
Description (OCR text may contain errors)
l [221 Filed:
United States Patent Kasazima a [541 SINGLE coN'rRoL DEVICE FOR PL RAL VARIABLE RESISTORS  Inventor; Masao Kasazima, Tokyo, Japan  Assignee: Alps Electric Co., Ltd., Tokyo,
' Japan Jan..28, 1972 21 Appl. No 221,733
301- Foreign Application Priority Data A,
Feb. 3, 1971 Japan ..-....4 6/3773 52] U.S.Cl.. ..33s/128,33s /9o 511 int. Cl. "non 9/02  Field of Search ..338/l28, 130, 131, 90
 References Cited UNITED STATES PATENTS,
3,372,359 3/1968 Wilson ..338/l28 3,629,775 l2/l971 Kindred ..338/128 Primary Examiner-Lewis l-l. Myers Assista'nt Examiner-D. A. Tone Attorney-Maxwell James et al.
[151 3,701,963 [451 Oct. 31, 1972 571 I ABSTRACT An improved control device for use in volume adjustment of a multi-speaker sound system is provided with means for simultaneously adjusting the volume of some or all of the speakers in the system. A plurality of variable resistors are mounted on an insulating substrate, the effective resistanceof each resistor being adjustable by sliding contact means.
I In a first embodiment of the invention an independent sliding contact means is provided for each variable resistor, those sliding contacts being simultaneously adjustable by means of a control knob operatively connected to a crossover linkage arrangement. The control knob extends through a window in the, housing whereby the position of the apparent sound source is adjusted by reference to the position of the control knob within the housing substrate.
' In a second embodiment of the invention the individual resistors each comprise a unique resistive pattern and a single carrier is provided with a plurality of sliding contacts engaging that resistive pattern in a predetermined manner in response to the manual operation of the control knob.
10 Claims, 16 Drawing Figures PATENTEDucranarz 3 7 'SHEEISUFS' SINGLE CONTROL DEVICE FOR PLURAL VARIABLE RESISTORS mechanism. The audio signal is applied to one end of a resistive element, the other end of said element being connected to areference voltage source. The speaker through its associated amplifier is operatively electri- I? eliminate'the above-mentioned problems by providing cally connected to the wiper of the'variable resistance device whereby adjustment of the wiper position along the resistive'element is effective to vary the voltage of the operatively utilized pointalong'the length'of the resistiveelemen't, thereby to regulate the audio volume of the speaker.
"With the advent of stereo sound systems it was found necessary and desirable to provide a volume balance adjustment mechanism to enable the listener to control the position of a balanced output from the two channels. In typical 'prior' art systems of this type each speaker is provided with avariable resistor device, said device being appropriately operatively connected to a common rotatable control knob which is thereby adapted to simultaneously increase or decrease the volume of one speaker relative to the volume of the other. The listener merely adjusts the balance control knob" in accordance with thedesired position of the balanced sound source relative to the speakers. In the case where two additional speakers are provided an additional rotatablecontrol knob is necessary to adjust the balance of the two additional speakers. I A recent development in stereo sound systems is the four-channel stereo record or tape. In accordance with this new development four separate channels are provided and at least four speakers (one for each channel) number of parts necessary the number of channels, where more than two speakers are utilized, the provision for a separate variable. resistor mechanism for each speaker unduly increases the and the manufacturing expense. e I
In copending application Ser. No. 133,941, filed by l-liroaki Komatsu on Apr. i4, 197], now U.S. Pat. No. 3,662,313 entitled Single Control Device for Plural Variable Resistors, and assigned to the assignee of the present invention, there-is disclosed va control device for use involume adjustment of a multi-speaker sound system, of the type here described, adapted to simultaneous adjustment of the resistances associated with a plurality' of sound speakers by means of a single control knob so as to provide a balanced outputfor any desired listening position. Briefly, that device comprises a plurality of triangular shaped resistive elements disposed on a base member and operatively connected to a like number of sound speakers. The operative resistances and thus-the audio volume of each of the associated speakers is adapted to be adjusted simultaneously by'means of a plurality of electrical contacts car any desired position by means of a single control member extending through a window in the housing of the device, that window being adapted to provide accurate visual indication of the resulting apparent sound source.
are positioned within the listening room, generally with two speakers in front of the listener and two speakers at his rear. Increased listening enjoyment results from being surrounded and engulfed by sound. Ideally the listener should have the. illusion that he is actually sitting in the midst of the orchestra. The importance of a balanced output from the plurality of speakers is paramount in such a multi-channel sound system. Thus in order to obtain maximum listening pleasure the speaker outputs should be precisely balanced-in ac-, cordance with the listener's desire. The same is true for a dual channel system utilizing four or more speakers.
The desired position of the apparent sound source may be coincident with the listeners position or the listener may desire to move the apparent sound source away from the listening position depending upon the f particular selection he islistening to andhis individual taste. In either case, the use of two twin variable rev sistor control knobs is not only cumbersome but, par ticularly in the case of a four-channel stereo system,
becomes quite confusing to the listener. Proper speaker balance utilizing such prior art control mechanisms can be achieved only be exhausting trial and error and is While that device represents a major improvement-in the art, several limitations and drawbacks of that struc ture .will be apparent. Those drawbacks and limitations result primarily from the triangular configuration of the,
' resistive, elements utilized. Thus while in accordance with that configuration the sound source, based upon the vector addition of the audio volumes of the speakers involved could be accurately moved by a corresponding inovement of the control knob within the window with an accurate indication thereof, variations in the sound effect produced by the combination of relative and absolute audio volume of the speakers is somewhat limited. For example, in accordance with that structure the volume of only one speaker at a time could be reduced to zero. That would occur only when the control knob was moved completely to one corner of the indicating window and resulted in a maintenance of the maximum volume of three speakers while the fourth was reduced to zero. If the control knob wasmoved from the origin along either the X or Y axis to one side ofthe window,.the two speakers at that side of v the room would be maintained at maximum volume while the volume of the remaining two speakers at the other side of the room would be reduced by approximately one-half. Accordingly, the operator, by use of the control knob, could not test the balance 'of only two speakers without at least some interference or distraction from the output of the other two speakers.
1 Moreover, with the control knob at one of the extreme edges of the window, movement of that knob along the edge would have no effect on the balance between the volume of the speakers positioned atthat correspond ing side of the room (which speakers were held at the maximum volume) but would instead be effective to provide an adjustment of the balance between the volumes of the speakers at the other side of the room.
tion to the electrical terminals connected to the resistor patterns on the base. This structure not only increases cost of manufacture but may also significantly reduce reliability and resultin increased maintenance cost.
' It is a primary object of the present invention to provide an improved variable resistor of the type described adapted for use in volume balance adjustment of a multi-channel stereo sound system adapted to eliminate substantially all of the above-mentioned drawbacks. I
It is another object of the present invention to design a variable resistor of the type described which is simpler and more compact in construction and substantially more versatile than prior art structures of this type.
It is yet another object of ;the present invention to provide a single control device for plural variable resistor adjustment which utilizes a minimum of inexpensive parts and is inexpensive to manufacture and assem-- ble. g
It is still another object of the present invention to provide a variable resistor of the type described strate. Adjacent to each resistor and extending parallel the substrate and extending parallel to the aforemen tioned conductive and resistive strips. The carrier ral variable resistors and wherein the operator may test the volume adjustment 'of one or more'speakers independently of the others. v r
To these ends the present invention comprises a control device for use in volume adjustment of a multispeaker sound system and adapted to provide a versome or all of the speakers in the system. Broadly, a device constructed in accordance with the present invention comprises a plurality of variable resistors mounted on an insulating substrate, a cover member secured to the substrate and defining an enclosure, a carrier mounted for sliding movement within that enclosure for movement parallel to the substrate in any direction and having a plurality of electrical contacts wipingly engaging said plurality of resistors respectively. The carrier is provided with a control member or knob extending through a window in the cover member. That window is adapted tosimulate the listeningroom and the resistors are so arranged on the substrate that when they are properly electrically concontrol knob within the cover member window.
In a first embodiment of the invention, the resistors are in the form of four narrow strips of resistive material'disposed'along the sides of a generally square sub- .satile means for simultaneously adjusting the volume of members are provided with electrical contact members each having contacts biased into wiping engagement with the resistive and conductive elements thereby to provide an operative variable resistor circuit.
The carriers on opposite sides of the substrateare movable in unison viaslotted crossover booms. An elongated control knob extends vertically through the slots in both boomsat the crossover region, whereby movement of the knob is effective to simultaneously adjust the effective ,resistancesof all four resistors. In accordance with this embodiment, the resistive-strips may be varied in length and/or resistance value, thereby to :vary the adjustment characteristic-in accordance with individual desires and/or for use with rectangular rooms of varyingdimensions. Two additional embodiments of the crossover control boom configuration are described.
In a second embodiment of the present invention, the substrate is provided'with resistive patterns in a manner similar] to that I described in the aforementioned copending application. However, as here disclosed, the resistive patterns comprise a sandwich structure in which a resistive area is bounded on opposite sides by conductive areas. These patterns are so designed that one, two, or even three of the four resistors may be adjusted while the resistances of remaining resistors are maintained at zero. This featureprovides greater versatility and facilitates independent speaker balancing and testing for defective speakers and/or channels.
This embodiment also includes an improved contact structure wherein each of the four contact members are mounted for horizontal movement with a plate-like carrier member but are vertically slidable relative thereto and comprise a pair of contacts spring biased in opposite directions into wiping engagement with the resistive patterns on the substrate and opposing conductive areas disposed on a second substrate mounted above and parallel to the first substrate. This structural arrangement provides improved electrical contact and a smooth and reliable operation with increased operating life. i
To the accomplishment of the above and to such other objects as may hereinafter appear, the present invention relates to a control device for plural variable resistors as defined in the appended claims and as described herein, with reference to the accompanying drawings in which: v
FIG. 1 is a perspective view of an assembled control device constructed in accordancewith one embodiment of the present invention;
FIG. 2 is a top plan view of the deviceof FIG. I with the cover removed;
FIG. 3 is a cross sectional view taken along the line 3-3ofFIG. l;
FIG. 4 is a circuit diagram of the variable resistors of FIG. 1;
FIG. 5 is a circuit diagram similar to FIG. 4 showingthe variable resistors operatively connected in a fourchannel sound system;
FIG. 6 is a schematic illustration of a room containing four stereo speakers;
FIGS. '7A-7D are plan views showing four illustrative I embodiments of a substrate for use in the control device of FIG. 1, the substrate of FIG. 7D being designed for use in connection with an elongated rectangularroom;
FIGS. 8A and 8B are perspective views of two additional embodiments of a crossover control boom structure for use in the control device of FIG. 1;
FIG. 9 is a perspective view of an assembled control device constructed in accordance with a second embodiment of this invention;
- FIG. 10 is an exploded perspective view of the control deviceof FIG.9; and
FIGS. 11 and 12 are plan views of two embodiments of. an insulating substrate for use in the control device ofFIG.9.- v
The present invention will be here specifically described for use in a four-channel stereo system having four speakers, one for each channel. It will be apparent, however, that the device may be modified for use with other multi-channel sound systems having any number of channels and/or speakers.
Referring now to the drawings wherein like reference numerals designate like or corresponding parts throughout the several views and particularly to FIG. 1, there is shown an assembled control device in accordance with one embodiment of the present invention. That device comprises a substrate or base plate generally designated 10 and a cover member generally designated 12. Cover member 12 comprises a top wall 14 having a generally square window or aperture 16 and four bent over side walls 18 having a plurality of tabs 20. The cover member 12 is secured to base plate- 10 by tabs 20 received in registering notches'22 in the base plate and bent thereover.
Base plate '10 preferably comprises a thin square substrate of electrically insulating material and as best shown in FIG. 2, is provided with four pairs of electrically operative elongated strips 24 and 26 extending along its four sides, respectively. The outer strips 24 comprise resistive material 24 along a major portion of the length thereof, the segments 24" at either end comprising conductive (i.e. metallic) material A pair of electrical terminals 28 are affixed to conductive areas 24" at either end of strips 24 and extend through slots 30 in substrate 10 for the purpose of external electrical connection.
Inner strips 26 are formed of conductive material along their entire length and are eachprovided with one electrical terminal 32 at one end extending through a slot 34 in substrate 10 for external electrical connection.
Elongated guide rails generally designated 36 are operatively secured to the substrate 10 and extend between strips 24 and 26. As best shown in FIG. 3,
' guide rails 36 are provided'with a rounded upper surface, each adapted to provide a guiding slide support for a carrier member generally designated 38. Each carrier member 38 is formed of a suitable electrically insulating material and is provided at its lower surface with a rounded groove 40 adapted to seat on guide rail 36 for sliding movement therealong. Depending from the lower surface of carrier 38 at either side of guide rail 36 are resilient electrical contacts 42 adapted, when carrier 38 is urged into sliding engagement with rail 36, to wipingly engage strips 24 and 26on substrate 10. In the embodiment shown, three contacts 42 are provided on each carrier member, two engaging the strip 24 and one engaging the strip 26. Those contacts are all electrically connected to one another in any suitable manner (not shown) (for example, by being formed integral on a single contact member having a connecting segment secured to the carrier 38 above the groove 40), thereby to electrically connect the strips 24 and 26.
Carriers 38 are formed with upwardly extending tongues 44. Tongues 44 are receivedv in vertical slots 48 formed in sliding blocks. 46, those blocks being disposed between carriers 38 and the upper wall 14 of cover member 12 and being adapted to urge carriers 38 into sliding engagement with their respective guide rails 36. As a result, carriers 38 are moved along guide rails 36 by their engagement with blocks 46. To facilitate smooth low friction sliding of block 46, those blocks are formed with rounded upper surfaces 50, those surfaces slidably engaging a thin sheet of low friction material 52 disposed between wall 14 of cover member 12 and blocks 46. Sheet 50 is formed with a window 52 registering'with window 16 in wall 14 to accommodate the control mechanism hereinafter described.
Opposing blocks 46 are affixed to opposite ends of a pair of control booms 54 in any suitable manner. As best shown in FIGS. 2 and 3, booms 54 extendin mutually perpendicular crossover relationship and are provided with longitudinally extending slots'56, those slots defining at their crossover point a generally square aperture 58. An elongated vertically extending control knob is received in aperture 58 through the slots 56 in both booms 54 and extends upwardly through windows52 and 16 in sheet 50 and wall 14 0f cover member 12, respectively. Control knob 60 is supported at its lower end by a rectangular base member 62, that base member being larger than aperture 58 in booms 54 and being provided with a downwardly extending teat 64 slidably engaging the substrate 10. Control knob 60' is preferably provided at its lower end 66 with a squarecross section being snugly'received in square aperture 58 and at its upper end 68 with a generally cir cular cross section to facilitate manual gripping.
' In accordance with the above construction, it will be appreciated that control knob 60 may be moved along either or both of longitudinal slots 56 in booms 54 to any location within window area 16, and when so moved is adapted to adjust the positions of booms 54 along the opposite sides of substrate 10 bridged by those booms. Booms 54, in turn, via the sliding blocks 46 at either end thereof are adapted to control the position of carriers 38 alongguide rails 36 and thus the position of contacts 42 along strips 24 and 26 thereby to vary the efi'ective length of resistive material 24' operatively connected in the external circuit, between one of the terminals 28 and terminal 32. For example, in a typical embodiment, terminals 28 of resistive strip 24 would be connected in operative circuit arrange ment with a multi-speaker sound system and conductive strip 26 would be grounded through terminals 32, whereby a variable length of resistive material 24' is operatively connected in the speaker system via terminal 28, contacts 42, conductive strip 26 and terminal FIGS. 7A-7D show alternative arrangements of the strips 24 and 26 on substrate 10, in which the four inner and outer strips are operatively connected to each other in a closed loop. In the embodiment of FIG. 7A, one of the two terminals 28 at either end of the strips 24 are eliminated and the conductive area 24" at that end is extended and operatively connected to the terminal 28 of the adjacent strip 24. The conductive strips 26 are connected .at their intersecting corners in a closed loop, a single terminal 32 being provided at one corner. This structure results in a simplification of the wiring system.
The embodiment of FIG. 7B is identical to that of FIG. 7A with the exception that the strips 24 comprise resistive material 24' along a length greater than the adjustment span L of the carriers 38, whereby the contacts 42 remain engaged with resistive material 24' along the entire adjustment span of carrier 38, thereby to vary the effective resistance from a maximum value at one end of the span to a minimum value (other than zero) at the other end of the adjustment span. In accordance with this arrangement, .sound is always emitted from all four speakers and unnatural sound field generation is minimized.
The embodiment of FIG.'7C is again substantially identical to that of FIG. 7A with the exception that the conductive strips 26 are operatively connected to a centrally located terminal by means of intersecting conductive strips'27.
The embodiment of FIG. 7D also utilizes the structure of FIG. 7A but is rectangular in configuration, the
length of one pair of resistive strips 24 being greater than that of the other. The two pairs of strips may be made of different resistive materials whereby the effective resistance of the longer strips is equal to that of the shorter strips thereby to maintain effective four speaker balance. This configuration is utilized with a correspondingly rectangular window area in the cover member to facilitate adjustment of the sound source within a rectangular room (or where the speakers are situated in a rectangular configuration other than a square). I .7
The electrical circuit embodied in a control device of the type thus far described using one of the substrate configurations of FIGS. 7 A-7D is best illustrated by the circuit diagram of FIG. 4, wherein the four terminals 28 are represented by nodes a-d, the four resistive strips are represented by resistors R R R and R and the terminal 32 is represented by node e. The node 60 represents the control knob 60 in FIG. 1 and the slider contacts 42 engaging the resistive strips are represented by pointers P P P and P As there shown, node e is grounded and the corner nodes a, b, c and d are operatively connected in circuit arrangement with the four channels Cl-I 1-CI-I4 of a sound system.
One such circuit arrangement is illustrated in FIG. 5. As there shown, each channel comprises a terminal TR at which the audio signal is introduced. That signal is amplified by a preamplifier PA and then passes through a master amplifier MA to its respective speaker SP.
Volume adjustment for individual channels is effected through attentuation of the audio signal at nodes n -m. Those nodes are each connected to one of the For example, in the central position of knob illustrated, all four speakers will have equal sound volume. If control knob 60 is moved toward node b to its extreme upper'right hand position in FIG. 5, the signal levels at nodes a, b and c will be maximally attenuated (in the embodiment of FIG. 7A these nodes would be grounded resulting in no audio signal at all at the output of the respective preamplifiers), and the audio signal at node d will be minimally attenuated. As a result, the volume of speaker SP3 is increased to its maximum level while the volume at speakers SP1, SP2 and SP4 is decreased, to their minimum levels. If as shown in FIG. 7B, the adjustment span of the sliding contacts extends the full length of the resistive strips, the. signal (voltage) level at each of nodes a-d varies between a maximum of one-half RI to a minimum of zero where R is the resistance of the full length of each resistor strip and I is the current.
As illustrated in FIG. 6, the speakers should be arranged in a configuration corresponding to the window 16 within which the control knob 60 is movable. Thus it is seen that speaker SP3 is located at the upper right hand corner of a square listening area so that movement of the control knob 60 to the upper right hand corner (nodes b and n )-of the window 16 of the control mechanism is effective to move the apparent sound source to the corresponding corner of the listening area It will be appreciated that various crossover linkages other than that shown in FIGS. 2 and 3 may be utilized illustrated in FIGS. 8A and 8B. a
In theembodiment of FIG. 8A, a pair of control rods 72 having a generally circular cross section are received respectively through a pair of mutually perpendicular but vertically spaced circular apertures 74 in a square block 76 affixed to the lower end of control knob 60. The carrier members here designated 38 comprise rectangular blocks having slots 78 adapted to receive the opposing ends of rods 72, whereby movement of the knob in any direction results in the mutually perpendicular sliding movement of the carriers associated with those rods.
FIG. 8B shows a construction similar to that of FIG. 8A. However, in this embodiment the crossover members are in the form of flattened elongated members 80 received in narrow crossover slots 82 and formed with resilient fork-like fastening members 84 at opposite ends. The carriers 38" are in turn formed with corarecontrolled by four separated carrier members movable by means of a pair of crossover linkage members.- That structure has certain advantages over the stallation. Moreover, the device may be easily modified for use with arectangular room-of other than a square configuration merely by lengthening the resistive strips on one pair of sides of thebase while maintaining the total resistance value of the stripthe same (i.e., as by using a material of slightly different resistance per inch). Indeed; if desired the per inch resistance of individual resistive'strips may be varied to providedifferent adjustment sensitivities. However, the versatility of this construction is somewhat limited with regard to desired variations in balancing patterns. Thus the volume at each speaker depends on the effective resistance of twostrip's so 'thattwo speakers cannot be balanced independently of the other two. This limitation presents a significant problem when it is desired to test the operativeness of one or more speakers and/or channels or to vary the balance-in accordance with particular selection being played The embodiment illustrated in FIGS. 9-.-l2 is designed to provide such versatility while maintaining a simple and reliable construction which is easy to assemble and install. As illustrated in FIGS. 9 and 10, that device is similar iii-construction and operation to the device disclosed in the aforementioned copending Ko-. matsu application and comprises a substrate 110 and a cover member 112 designed to-fit over substrate 110 and be securedthereto by depending tabs 120 received within slots 122 in a manner identical to that already described with respect to FIG. 1. The cover member is provided with a window 116 in its top wall 118 through which the control knob 160 extends. Affixed to the lower end of control knob 160 is a single carrier member 200 inthe form of a generally square plateof insulating materialhaving stepped portions 202 on its underside along two parallel edges. Carrier 200 is provided with four small apertures 204, one near each corner, those apertures slidably receiving contact elements 206. Each contact element comprises a pair of oppositely facing metallic contacts spring biased away from each other by a small compression coil spring 210 disposed therebetween.
Carrier member 200 is mounted for universal sliding movement between substrate 110 and a second plate of insulating material 212 by means of a universal slide linkage comprising a rectangular guide frame 214 having guide rails 216 slidably supporting carrier 200 along stepped portions 202 for movement in a first direction indicated by arrow 218, that frame being itself slidably the 110. In addition, plate 212 is provided with a window 230 adapted to register with window 116 on cover member 112 through which control knob 160 is received. 1
As illustrated in FIG. 10, each conductive area 228 on the lower surface of plate 212, is electrically connected to a terminal 232, said terminals being secured 118 of cover member 112 and are provided with slots in pairs on two oppositely extending tongues 234 formed integral on plate 212. Those tongues are received through openings 236 in opposite side walls 238 receiving tabs 240 depending from the top wall 114 of cover member 112, thereby to laterally stabilize plate 212 within the assembly. I
in assembling the device guide frame 214 is mounted on guide rails 220, carrier member 200 is mounted on frame 214, plat'e'212 is placed atop carrier 200 and supported in that position by the four upwardlyfacing contacts 208, control knob 160 extending throughwindow 230, and finally covermember 112 is disposed atop plate 2l2,'tabs 240 being received in slots.238, and is secured to substrate 110 by tabs 120 received through slots 122 and bent under substrate 110. When the device is thus assembled coil spring 210, on each contact member 206 is compressed between substrate 110 and plate 212, whereby contacts 206 establish firm electrical connection between the registering electrical elements 226 and 228 on substrate 110 and plate 212, respectively, and are moved along those elements by carrier member 200. Because contacts 206 are vertically movable within apertures 204 in carrier member 200, those contacts float between substrate 110 and plate 212 exerting equal pressure on both.
As, best illustrated in FIG. 10, electrically operative elements 226 on substrate 110' each comprise a resistive area R sandwiched between two conductive areas A and B. The resistive area R-isin the form of a strip extending between the two adjacent outer sides of the square element 226, and having a generally L- shaped outer boundary 242 with the outer conductive area A and an arcuate inner boundary 244 with the mounted on a pair of guide rails 220 by means of I stepped portions 222 for movement in a second direction indicated by arrow 224 perpendicularto said inner conductive area B. Consequently, the inner conductive area B encompasses both adjacent inner sides of the square elements 226.
I Terminals T are operatively electrically connected to the outer conductive areas A at the outer corners of the elements 226. The inner conductive areas B are operatively electrically connected to terminals T at the inner corners .of elements 226. Terminals T and T extend throughappropriate slots in the substrate 110 for external electrical connection to a sound system. That electrical connection is made in a manner identical to that shown and described in the aforementioned copending Komatsu application and accordingly will v not be described in detail here. Suffice it to say that the volume of each of four speakers is controlled by the effective resistance connected between the grounded terminals T' on substrate 110 and the terminals 232 on plate 212.
As best illustrated in FIG-11, when the control knob is located centrally of substrate 110 (centered within the window 116), the contacts 208 are located centrally of elements 226 at the boundary 242 between the resistive areas R and the outer conductive areas A. v
Consequently, the entire resistive area R is connected between terminals T and terminals 232 (via contact members 206 and conductive elements 228) whereby substantially maximum volume is emitted from all four speakers. When the knob 160 is moved to its extreme position at one of the corners of window 116, for example to the upper right hand corner as illustrated in FIG. 11, the upper right hand contact 208 remains engaged with the outerconductive area A and the other three contacts are moved fully. across resistive areas R R and R, into engagement with the inner conductive areas 8,, B and 8,, respectively. As a result the volume of one speaker, associated with the upper right hand element 226, remains at its maximum level, while the volume of the remaining three speakers is reduced to zero. As noted with respect to the embodiment of FIG. 1, this configuration is desirable for testing the performance of a particular speaker and/or channel without interference from I the remaining speakers and/or channel.
A second desirable feature of the resistive pattern here illustrated is the ability to test the balance between any two adjacentspeakers without interfering audio from the other two speakers. For example, when the knob 160 is in the upper right hand position illustrated in FIG. 11, the balance between the two upper resistors R, and R or the two right hand resistors R and R may be independently adjusted merely by sliding the knob in the horizontal or vertical direction, respectively. It will be apparent that under these conditions the effective resistance of the remaining two resistors is maintained at zero value because their respective contacts slide along the inner conductive areas B thereby shorting out the audio signal for those speakers.
It will be appreciated, that unlike the embodiment of FIG. 1 the resistive patterns here illustrated provide maximum resistance (i.e., maximum volume) to all four channels when the control knob is centrally located within the window, the resistance (volume) of one or more of those channels decreasing upon movement of the control knob away'from the center of the window.
Finally, it has been found that the resistive pattern herein described provides exceptionally good accuracy in adjusting the apparent sound source by visual reference to the location control knob within the window opening in the cover member combined with increased versatility in providing pleasing sound effects.
Since, in operation, the inner terminals T are all grounded, those terminals may be conveniently replaced by a central conductive area C operatively connecting all four inner conductive areas B to a single central terminal T, as illustrated schematically in FIG. 12.
It will be appreciated. from the foregoing that the present invention represents a significant improvement in accordance with this invention provides increased versatility and superior operating characteristics as compared to prior art structures.
The crossover-construction shown in FIG. 1 is particularly useful in connection with elongated rectangular listening areas or where variations in the sensitivity of balance adjustment in mutually perpendicular directions is desired. Moreover, that configuration results in a simplified wiring system in which all external connections are made to terminals on the substrate.
The embodiment of FIG. 9 provides an extremely compact structure having improved floating electrical contact means andenhanced versatility which enables'independent volume adjustment of one or more speakers. 1 7
While only a limited number of embodiments of the present invention have been herein specifically disclosed, it will be appreciated that many variations may be made therein without departing from the scope of the invention, as defined in the following claims.
lclaimz I v 1. In a control device for use in volume adjustment of a multi-speaker sound system comprising a housing, a plurality of electrically operative elements each having a resistive pattern operatively mounted on said housing, a carrier mounting a plurality of contacts, said plurality of contacts slidably engaging said plurality of electrically operative elements, respectively, means for moving said carrier within said housing in at least two dimensions thereby to simultaneously move said con-- tacts slidably along their respective electrically operative elements, thereby to simultaneously vary the operative resistances of said electrically operative elements, means on said housing to visually correlate the position of said carrier with the relative values of said operative resistances, the improvement wherein said resistive patterns include'at least two conductive areas separated from each other'by a resistive area on said electrically operative elements such that one or more of said contacts may engage one of said conductive areas on their respective electrically operative elements while the remaining contacts simultaneously engage the other of said conductive areason their respective electrically operative elements, whereby when said contacts are operatively connected respectively to a plurality of sound speakers and said electrically operative elements are electrically connected to an audio signal, the position of the apparent sound source may be conveniently varied by reference to the position of said carrier. v
2. The control device of claim 1, wherein said resistive patterns are shaped to allow balancing of the effective resistances of one pair of electrically operative elements while the effective resistances of the other electrically operative elements are maintained at a value of zero. g
3. The control device of claim 1, wherein'said housing comprises a rectangular substrate, there being four electrically operative elements arranged symmetrically on said substrate, and wherein said other conductive area of each of said elements extends along the full length of two adjacent sides of said element rectangle, whereby movement of said contacts along said two adjacent sides of one of said elements is ineffective to dary between said resistive area and said one conductive area is L-shaped.
- l3 5. The control device of claim 4, wherein the boundary between said resistive area and said other conduc tive area is arcuate. v
6. A control device for use in volume adjustment of a multi-speaker sound system, comprising a first plate of electrically insulating material, a plurality of first electrically operative elements disposed on said first plate, first terminal means on said first plate operatively electrically connected to said elements, a second plate of dicular to said plates, each of said contact elements comprising first and second electrical contacts extending in opposite directions toward said first and second plates, respectively, and resilient bias means operatively connected between said first and second contacts and effective to bias said contacts away from each other and into wiping engagement with opposing first and second electrically operative elements, respectively, said electrically operative elements on at least one of said first or second plates comprising a resistive pattern, whereby when said first and second terminal means are connected in operative circuit arrangement with said plurality of speakers, the position of the apparent sound source may be varied.
7. The control device of claim 6, wherein said resilient bias means comprises a compression coil spring.
8. The control device of claim 6, wherein said resistive patterns are shaped to allow balancing of the effective resistances of one pair of electrically operative elements while the effective resistances of the other electrically operative elements are maintained at a value of zero.
9. The control device of claim 7, wherein said resistive patterns include at least two conductive areas separated from each other by a resistive area on said electrically operative element such that one or more of said contacts may engage one of said conductive areas while the remaining contacts simultaneously engage the other of said conductive areas on their respective electrically operative elements.
10. A control device for use in volume adjustment of a multi-speakersound system comprising a substrate and a cover member operatively connected to said substrate to define a housing enclosure, said substrate having a plurality of resistive strips disposed along the periphery of said substrate and a plurality of conduc tive strips disposed adjacent and parallel tosaid re sistive strips thereby to define parallel pairs, first terminal means on said substrate operatively connected to said resistive strips, second terminal means on said sub! strate operatively connected to said conductive strips, a
plurality of sliding contact means slidably mounted within said enclosure for movement along said parallel pairs of strips, respectively, said cover member having a window opening, a control knob extending out from said housing enclosure through said window, and means operatively connected between said control knob and said plurality of sliding contact means and effective upon movement of said control knob within said window area in a direction parallel to said substrate to simultaneously adjust the effective length of said resistive strips operatively connected between said first and second terminal means, whereby when said first terminal means are connected, respectively, to a plu rality of sound speakers and said second terminal means is grounded, the position of the apparent sound source may be conveniently varied by reference to the position of said carrier within said window.
' i II!