CA1131133A - Turntable assembly - Google Patents
Turntable assemblyInfo
- Publication number
- CA1131133A CA1131133A CA339,817A CA339817A CA1131133A CA 1131133 A CA1131133 A CA 1131133A CA 339817 A CA339817 A CA 339817A CA 1131133 A CA1131133 A CA 1131133A
- Authority
- CA
- Canada
- Prior art keywords
- record
- turntable assembly
- turntable
- spindle
- platter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
- G11B19/20—Driving; Starting; Stopping; Control thereof
- G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/02—Cabinets; Cases; Stands; Disposition of apparatus therein or thereon
- G11B33/022—Cases
Landscapes
- Holding Or Fastening Of Disk On Rotational Shaft (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The components of a turntable assembly are improved so as to eliminate the vibrations ordinarily transmitted from these components to the stylus; the improved components include the suspension, the spindle bearing, the platter and the sub-chassis; the invention is also concerned with a cup-shaped member which is engaged to the top portion of the spindle and which applies pressure on the peripheral edge of the label area of the record to cause the record to come in suction contact with the mat whereby the vibrations may be transmitted to the mat rather than to the stylus.
The components of a turntable assembly are improved so as to eliminate the vibrations ordinarily transmitted from these components to the stylus; the improved components include the suspension, the spindle bearing, the platter and the sub-chassis; the invention is also concerned with a cup-shaped member which is engaged to the top portion of the spindle and which applies pressure on the peripheral edge of the label area of the record to cause the record to come in suction contact with the mat whereby the vibrations may be transmitted to the mat rather than to the stylus.
Description
1~3~13~
FIELD OF THE INVENTION
The present invention pertains to a turntable assembly and to improved components thereof.
BACKGROUND OF THE INVENTION
For a long period of time, it was thought that any improvements which could be made to the components of the turntable structure of a record player would only result in a better operation of the mechanism associated with the sound reproducing system. More recently, it has been established that turntables could be improved to retrieve more information from a record disc.
The musical information on a record is contained in the wiggles of the groove as it spirals in across the disc; wiggles are a mechanical analog of the waveforms originally generated by the instruments into the surrounding air at the recording session and subsequently picked up by a microphone with the ultimate goal of being fed from the disc into the record player system without any modification whatsoever. The stylus vibrates mechanically in exact accordance with the undulations in the groove; this mechanical vibration is transduced within the cartridge body into an electrical signal which is fed into the phonograph preamplifier. It therefore follows that any mechanical vibration that is not part of the information in the groove is also read by the stylus and fed into the sound reproducing system. It becomes obvious that isolating the stylus from extraneous mechanical vibration is of paramount importance in the design of a turntable. In other words, the stylus must play only the groove not the disc itself, or the turntable platter, or the chassis, nor must it be influenced by the surrounding accoustic environment, accoustic energy in the air from the speakers, people walking by, motor vibration, suspension vibration, etc. It has been observed that turntable designers have in the past paid little attention to these performance criteria and have ignored the most ,~
single important source of extraneous mechanical vibration: the disc itself.
Vinyl is an excellent medium for storing information in the form of undulations in a spiraling groove; however, the record playing process excites some very severe side effects inherent in the nature of this material. As the stylus accelerates laterally and vertically to follow the groove undulations, forces are generated in the order of 1000g. A11 materials have an inherent resonance that can be excited if enough energy is applied and vinyl is actually quite a lively material in this sense. Much of the brittle harshness in modern music systems is actually a result of the stylus reading these mechanical vinyl resonances which have been excited by the stylus itself.
Vinyl is also an elastic material, meaning that energy that is fed into it, is actually absorbed for a certain length of time and then released over a certain length of time. One drawback is that a transient is played by the stylus thereby generating a shock wave into the disc. The transient can be heard and its echoing back can also be heard as the vinyl releases the stored shock wave over time. A major audible effect is a general blurring and smearing of all musical details since this process is going on throughout the entire duration of the playing of the record. Due to the liveliness and elasticity of the vinyl of the disc, accoustic energy in the room that travels through the air and strikes the disc (mostly from speakers, but actually including all noise or sound in the room) is reflected or stored by the vinyl and is retransmitted back to the stylus as unwanted vibration. There results further blurring of detail usually accompanied by boominess in the bass.
Warps in the vinyl upset the stability of the entire playing system, actually causes a change in the pitch of music in the grooves that the warps deform and, in general, create severe subsonic problems throughout the entire reproduction chain. A warp also results in a portion of the record being suspended in free air, which increases its susceptibility to all kinds of excitations dramatically.
In order to allow only the information in the groove to be played, the groove must be isolated from the rest of the disc; in other words, the groove must be isolated from any vibration which can be transmitted thereto from any component of the record player.
OBJECTS AND STATEMENTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved turntable assembly which overcomes the drawbacks mentioned above.
It is also an object of the present invention to isolate the stylus from unwanted mechanical vibrations in the vinyl of the disc and from unwanted vibrations in the record playing system.
These objects are achieved, in one instance, by mounting on the turntable means which raises the record slightly in the label area of the disc and by mounting on the spindle, means to apply pressure on the label area to thereby achieve a distribution of even pressure over the entire grooved surface of the disc. This results in damping vinyl resonances; it also eliminates the vinyl as a storage medium, the stored energy being instead transmitted to the mat which comes in intimate contact with the vinyl through suction since a vacuum is created under the disc. Because the vinyl is under too much tension to react significantly to outside energy, transmission of accoustic energy by the vinyl to the stylus is prevented and also elimination of warps is obtained. Hence, the groove is isolated and the stylus can only read the information in the groove.
Therefore, the present invention relates to a turntable assembly which comprises: a spindle, a platter ~3~l33l mounted for rotation of the spindle, a mat on the platter for receiving a phonograph record having, on upper and lower faces thereof, a label area and a grooved playing area to be engaged by a phonograph stylus, means located beneath the record and confined within the label area of the record to raise the record centrally thereof, and means mounted on the spindle over the record for applying pressure on the peripheral edge of the label area on the top face of the record to thereby force the grooved playing area of the lower face in suction contact with the mat whereby vibrations in the record may be trans-mitted to the mat rather than to the stylus.
The present invention is also concerned with eliminating unwanted vibrations in the entire record playing system; hence, the present invention also relates to improvements to certain components of the turntable assembly.
THE PLATTER
A turntable platter is usually made of metal and 2Q always has a large surface area which makes it very prone to resonances and mechanical vibrations in general. Most turntables rely on their mats to damp the platter.
It is an object of the present invention to have the platter inherently non-resonant.
The present invention therefore relates to a turntable platter which comprises: a circular body made of a metallic rigid material having a flat record receiving surface and a peripheral wall downwardly extending from said surface; groove means in the peripheral wall; and vibration absorbent material received in the groove to act as a wave trap for vibrations travelling through the metallic body.
THE BEARING
The spindle on which is supported the platter is usually supported itself on a journalled bearing that is mounted to the body of the record player. In some cases, the spindle is mounted on a thrust pad. If the latter flexes, vertical motion, on a very small scale, of the entire platter results in the stylus reading this as a subsonic signal: rumble is obtained.
The present invention provides on the lower extremity of a spindle a tip made of extremely hard material which rests on a ceramic thrust pad, which is also extremely hard, to thereby prevent vertical motion of the spindle. The hardness of the material also prevents wear in this thrust pad. The bearing assembly further includes bushings made of extremely hard plastic material, to provide a perfect fit between the spindle and the bearing. Due to the use of such plastic material, friction is almost non-existent which is most important in reducing the load on the motor as well as insuring ever smooth rotation of the spindle in the bearing. This material does not create noise but actually absorbs and dissipates into the sub-chassis any vibrations that may be created by the rotational process. This vibration absorption, of course, contributes significantly to groove isolation since it is helping to keep extraneous mechanical vibrations from getting to the record and therefore to the stylus.
Hence, the present invention relates to a bearing assembly for phonograph record player which comprises: a housing having an opened end, the housing having a cavity defined by a cylindrical inner wall and a bottom end wall; a spindle axially mounted in the housing and having an upper portion extending outside the housing for supporting a turntable thereon; a tip tightly mounted to the lower end of the spindle, the tip being made of a hard wear-resistant material; a thrust pad mounted on the bottom end wall of the housing and receiving the tip thereon, the thrust pad being made of a hard wear-resistant material; and vibration absorbent means mounted between the spindle and the cylindrical wall of the housing for maintaining the spindle axially in the cavity.
THE SUSPENSION
The fundamental purpose of a turntable suspension is to act as a mechanical filter for outside vibrations; in other words, any vibrational energy above the tuned suspension frequency is prevented from entering the playing system. In general, the lower the tuned suspension frequency the better: the closer to OHz, the less energy that exists in the surrounding environment to interact with the turntable.
Therefore, the present invention is also concerned with providing an improved suspension wherein the center of gravity of the entire floating assembly is at exactly the same height as the fixing points of the turntable sub-chassis to the suspension assembly. This makes the playing assembly immune from any horizontal swaying (vibration) that can be induced by the rotation of the platter itself at start up or from outside sources.
In presently known turntables, the fixing points of their suspension springs are at a much different level than at the center of gravity of the playing system.
Also, there is a large vertical displacement between the center of gravity of the moving mass and the spring fixing points; the latter, therefore are pivot points around which the entire sub-assembly can sway horizontally. This, of course, is not possible with the suspension of the present invention due to the coincidence of the center of gravity and the spring fixing points. In other words, the entire floating sub-assembly is inherently stable thus rendering it extremely immune to shock such as that caused by people walking near the shelf or table on which the turntable is mounted and also to rotationally induced sway.
The present invention is also concerned with a suspension system for supporting a turntable sub-chassis 113~
which comprises: a plurality of suspension assemblies, each assembly including a top housing having means to receive thereon the sub-chassis; rod means extending vertically through each housing; spring means having one end suspended from the rod means; and vibration absorbent means having one portion supported at the lower end of the spring means and a second portion supporting the top housing for decoupling the spring means from the sub-chassis.
In one preferréd form of the present invention, the springs are effectively decoupled from the sub-chassis support housing by means of two different materials. The nylon housing support is the primary isolator between the springs and the floating assembly; however, it is further isolated from the spring housing top assembly (i.e. the sub-chassis support) by a layer of sponge rubber. The latter together with the nylon housing support effectively provide a barrier which blocks any vibration in the springs themselves from entering the sub-chassis. Furthermore, the sponge rubber also damps the spring housing top assembly and sub-chassis support. Still, the layer of sponge is effectively another "spring" that acts in conjunction (series) with the main spring but in the other direction:
the main spring acts in a downward direction by extension while the sponge spring acts in an upward direction by compression. The combination of these two modes in a dual action spring is very effective and once again makes a significant contribution to groove isolation. The present invention makes use of a spring support rod which pr~trudes-from the top of the spring housing making sub-chassis adjustment and levelling accessible from above, unlike other turn-tables which require removal of the bottom of the base, an extremely tedious and time consuming internal spring adjustment. Furthermore, conventional turntables of this type achieve their suspension adjustment by actually compressing and expanding the springs; this of course, ~131133 varies the tuning of the suspension in an unpredictable fashion. In the present turntable, rotation of the spring support rod to achieve levelling raises and lowers the entire spring assembly without compressing or expanding the springs. This of course, means that the suspension tuning is completely unaffected by suspension levelling.
THE SUB-CHASSIS
The present invention also relates to a sub-chassis for supporting a turntable of a phonograph record player which comprises a flat laminated structure having a plurality of arm extensions adapted to be engaged with and supported by suspension assemblies associated with the turntable; the laminated structure includes a plurality of layers of metals interspaced by means of vibration absorbent bonding layers.
Audible characteristics which can be obtained from an improved turntable assembly made in accordance with the present invention are: improved clarity, increased dynamic range, lack of mid-bass boom, deep bass control and extension, improved transient response without any brittle emphasis, smooth and seamless balance, from low bass to extreme highs, precise image without exceptional f^cus, natural depth perspective, airiness, lack of locational smearing, and new standard of audibility of intertransient silence between notes.
- Other objects and scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that this description, while indicating pref~rred embodiment of the invention, is given by way of illustration only since various changes and modifi-cations within the spirit and scope of the invention will become apparent to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a turntable ~ ~L31133 g assembly made in accordance with the present invention, some components not essential to the present invention having been omitted for clarity purposes;
Figure 2 is a top elevational view of the turntable assemb'y shown in Fig. l;
Figure 3 is an elevational, partly cross-sectional, view taken along lines 3-3 of Fig. 2;
Figure 4 shows a variant of the spacer means shown in Fig. 3; and Figure 5 shows a variant of the vibration absorbent means used in the suspension assembly illustrated in Fig. 3.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figs. 1-3, there is shown a turn-table assembly displaying the essential components of the present invention. Generally, the turntable includes a base 10 having at the rear two vertically extending hinge plates 12 to which is pivotally mounted a cover 14. The front portion of the base 10 also includes a plate 16 on GU which rests the front portion of the cover 14. This provides to the turntable assembly, when the cover is in the closed position, an aerated appearance since the cover is at a distance from base 10. The base plate 10 and the cover 14 are preferably made of a plastic material, such as acrylic.
The turntable assembly further includes a sub-chassis 18 having a large surface area and a series of projections that include three arm extensions 20, 22 and 24, one tone arm extension 26 and one spirit level extension 28. The three arm extensions 20,22,24 each include a circular opening so as to rest on and engage suspension assemblies 30,32 and 34, respectively.
The turntable assembly includes a platter 35 for receiving and the playing of a phonograph record 38 by means of a pick-up 36; the record has a grooved playing area 40 and a label area 42 (see Fig. 3). The l33 record extends over a mat 46, except for its peripheral edge, the mat resting on the top face of platter 35.
The platter 35 is centrally supported on a spindle 48 having a shoulder 50 on which the platter sits. The lower portion of the spindle 48 is received in a bearing assembly 52 which has its lower portion protruding through an opening 54 in the base plate 10.
A cone-shaped member 56 extends over the record and is connected to the spindle by means of a knob member 58 which is threadedly engaged with the upper portion of the spindle 48. The knob is engaged to the cone-shaped member by means of a spring clip 59 at the lower part of the knob stem. A small ring 60 is disposed to raise the record centrally thereof; in the embodiment shown, the ring is located between the record and the mat and is of a size so as to be confined within the label area of the record. It will be evident that the raising function could also be performedby a spacer ring located between the mat and the platter 35 or still simply by a raised portion in the construction of the mat 46 or of the platter 35. In one variant such as illustrated in Fig. 4, spacer 60 is tapered to assist in the suction effect between mat and record.
A more detailed description of each component will now be given together with a description of its role in reducing vibration which is ordinarily transmitted to th~ stylus of the tone arm in presently known systems.
One important feature of the present invention is the elimination of vibration transmitted by the record itself to the stylus. The peripheral edge 62 of the cone-shaped member 56 contacts the record 38 at about the periphery of the label area 42 of the record. By rotating knob 58 on the spindle, pressure is exerted on the record 38 which is raised centrally by the spacer 60. The appli-cation of an even force on the label area edge of the record against the central support member 60 forces the entire playing surface, i.e. the groove area 40 of the record, against the mat 46. The record 40 actually adheres to the mat through suction since a vacuum is created under the disc by the pressure exerted. The mat should therefore be flat without sculpted ridges in order that no air pockets be trapped under the disc;
these air pockets would themselves resonate and would excite the vinyl above them. The mat should also be made of a material which clamps with vinyl to absorb vibrations in the vinyl before they may be retransmitted to the stylus. The mat is made slightly smaller in diameter than the disc in order that the raised lip 64 of the record does not raise the outer portion of the disc into the air. As a result, the entire grooved surface of the disc is forced through the pressure applied against the elasticity of the vinyl into intimate contact with the mat. As indicated above, this results in damping the vinyl resonances themselves, in eliminating the vinyl as a storage medium, in preventing the transmission of accoustic energy by the vinyl to the stylus and in elimi-nating practically all warps.
The cone-shaped member includes a plurality of openings 65 to allow air circulation under the cone to prevent air from being trapped underneath.
The platter 35 of the turntable should be precision machined and preferably made of a magnesium-aluminum alloy which combines rigidity and strength. It is designed as a fly-wheel with the majority of the mass distributed around the peripheral edge 44 such as shown in Fig. 3; the momentum of the rotating fly-wheel overcomes the flutter induced in a turntable by the stylus playing
FIELD OF THE INVENTION
The present invention pertains to a turntable assembly and to improved components thereof.
BACKGROUND OF THE INVENTION
For a long period of time, it was thought that any improvements which could be made to the components of the turntable structure of a record player would only result in a better operation of the mechanism associated with the sound reproducing system. More recently, it has been established that turntables could be improved to retrieve more information from a record disc.
The musical information on a record is contained in the wiggles of the groove as it spirals in across the disc; wiggles are a mechanical analog of the waveforms originally generated by the instruments into the surrounding air at the recording session and subsequently picked up by a microphone with the ultimate goal of being fed from the disc into the record player system without any modification whatsoever. The stylus vibrates mechanically in exact accordance with the undulations in the groove; this mechanical vibration is transduced within the cartridge body into an electrical signal which is fed into the phonograph preamplifier. It therefore follows that any mechanical vibration that is not part of the information in the groove is also read by the stylus and fed into the sound reproducing system. It becomes obvious that isolating the stylus from extraneous mechanical vibration is of paramount importance in the design of a turntable. In other words, the stylus must play only the groove not the disc itself, or the turntable platter, or the chassis, nor must it be influenced by the surrounding accoustic environment, accoustic energy in the air from the speakers, people walking by, motor vibration, suspension vibration, etc. It has been observed that turntable designers have in the past paid little attention to these performance criteria and have ignored the most ,~
single important source of extraneous mechanical vibration: the disc itself.
Vinyl is an excellent medium for storing information in the form of undulations in a spiraling groove; however, the record playing process excites some very severe side effects inherent in the nature of this material. As the stylus accelerates laterally and vertically to follow the groove undulations, forces are generated in the order of 1000g. A11 materials have an inherent resonance that can be excited if enough energy is applied and vinyl is actually quite a lively material in this sense. Much of the brittle harshness in modern music systems is actually a result of the stylus reading these mechanical vinyl resonances which have been excited by the stylus itself.
Vinyl is also an elastic material, meaning that energy that is fed into it, is actually absorbed for a certain length of time and then released over a certain length of time. One drawback is that a transient is played by the stylus thereby generating a shock wave into the disc. The transient can be heard and its echoing back can also be heard as the vinyl releases the stored shock wave over time. A major audible effect is a general blurring and smearing of all musical details since this process is going on throughout the entire duration of the playing of the record. Due to the liveliness and elasticity of the vinyl of the disc, accoustic energy in the room that travels through the air and strikes the disc (mostly from speakers, but actually including all noise or sound in the room) is reflected or stored by the vinyl and is retransmitted back to the stylus as unwanted vibration. There results further blurring of detail usually accompanied by boominess in the bass.
Warps in the vinyl upset the stability of the entire playing system, actually causes a change in the pitch of music in the grooves that the warps deform and, in general, create severe subsonic problems throughout the entire reproduction chain. A warp also results in a portion of the record being suspended in free air, which increases its susceptibility to all kinds of excitations dramatically.
In order to allow only the information in the groove to be played, the groove must be isolated from the rest of the disc; in other words, the groove must be isolated from any vibration which can be transmitted thereto from any component of the record player.
OBJECTS AND STATEMENTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved turntable assembly which overcomes the drawbacks mentioned above.
It is also an object of the present invention to isolate the stylus from unwanted mechanical vibrations in the vinyl of the disc and from unwanted vibrations in the record playing system.
These objects are achieved, in one instance, by mounting on the turntable means which raises the record slightly in the label area of the disc and by mounting on the spindle, means to apply pressure on the label area to thereby achieve a distribution of even pressure over the entire grooved surface of the disc. This results in damping vinyl resonances; it also eliminates the vinyl as a storage medium, the stored energy being instead transmitted to the mat which comes in intimate contact with the vinyl through suction since a vacuum is created under the disc. Because the vinyl is under too much tension to react significantly to outside energy, transmission of accoustic energy by the vinyl to the stylus is prevented and also elimination of warps is obtained. Hence, the groove is isolated and the stylus can only read the information in the groove.
Therefore, the present invention relates to a turntable assembly which comprises: a spindle, a platter ~3~l33l mounted for rotation of the spindle, a mat on the platter for receiving a phonograph record having, on upper and lower faces thereof, a label area and a grooved playing area to be engaged by a phonograph stylus, means located beneath the record and confined within the label area of the record to raise the record centrally thereof, and means mounted on the spindle over the record for applying pressure on the peripheral edge of the label area on the top face of the record to thereby force the grooved playing area of the lower face in suction contact with the mat whereby vibrations in the record may be trans-mitted to the mat rather than to the stylus.
The present invention is also concerned with eliminating unwanted vibrations in the entire record playing system; hence, the present invention also relates to improvements to certain components of the turntable assembly.
THE PLATTER
A turntable platter is usually made of metal and 2Q always has a large surface area which makes it very prone to resonances and mechanical vibrations in general. Most turntables rely on their mats to damp the platter.
It is an object of the present invention to have the platter inherently non-resonant.
The present invention therefore relates to a turntable platter which comprises: a circular body made of a metallic rigid material having a flat record receiving surface and a peripheral wall downwardly extending from said surface; groove means in the peripheral wall; and vibration absorbent material received in the groove to act as a wave trap for vibrations travelling through the metallic body.
THE BEARING
The spindle on which is supported the platter is usually supported itself on a journalled bearing that is mounted to the body of the record player. In some cases, the spindle is mounted on a thrust pad. If the latter flexes, vertical motion, on a very small scale, of the entire platter results in the stylus reading this as a subsonic signal: rumble is obtained.
The present invention provides on the lower extremity of a spindle a tip made of extremely hard material which rests on a ceramic thrust pad, which is also extremely hard, to thereby prevent vertical motion of the spindle. The hardness of the material also prevents wear in this thrust pad. The bearing assembly further includes bushings made of extremely hard plastic material, to provide a perfect fit between the spindle and the bearing. Due to the use of such plastic material, friction is almost non-existent which is most important in reducing the load on the motor as well as insuring ever smooth rotation of the spindle in the bearing. This material does not create noise but actually absorbs and dissipates into the sub-chassis any vibrations that may be created by the rotational process. This vibration absorption, of course, contributes significantly to groove isolation since it is helping to keep extraneous mechanical vibrations from getting to the record and therefore to the stylus.
Hence, the present invention relates to a bearing assembly for phonograph record player which comprises: a housing having an opened end, the housing having a cavity defined by a cylindrical inner wall and a bottom end wall; a spindle axially mounted in the housing and having an upper portion extending outside the housing for supporting a turntable thereon; a tip tightly mounted to the lower end of the spindle, the tip being made of a hard wear-resistant material; a thrust pad mounted on the bottom end wall of the housing and receiving the tip thereon, the thrust pad being made of a hard wear-resistant material; and vibration absorbent means mounted between the spindle and the cylindrical wall of the housing for maintaining the spindle axially in the cavity.
THE SUSPENSION
The fundamental purpose of a turntable suspension is to act as a mechanical filter for outside vibrations; in other words, any vibrational energy above the tuned suspension frequency is prevented from entering the playing system. In general, the lower the tuned suspension frequency the better: the closer to OHz, the less energy that exists in the surrounding environment to interact with the turntable.
Therefore, the present invention is also concerned with providing an improved suspension wherein the center of gravity of the entire floating assembly is at exactly the same height as the fixing points of the turntable sub-chassis to the suspension assembly. This makes the playing assembly immune from any horizontal swaying (vibration) that can be induced by the rotation of the platter itself at start up or from outside sources.
In presently known turntables, the fixing points of their suspension springs are at a much different level than at the center of gravity of the playing system.
Also, there is a large vertical displacement between the center of gravity of the moving mass and the spring fixing points; the latter, therefore are pivot points around which the entire sub-assembly can sway horizontally. This, of course, is not possible with the suspension of the present invention due to the coincidence of the center of gravity and the spring fixing points. In other words, the entire floating sub-assembly is inherently stable thus rendering it extremely immune to shock such as that caused by people walking near the shelf or table on which the turntable is mounted and also to rotationally induced sway.
The present invention is also concerned with a suspension system for supporting a turntable sub-chassis 113~
which comprises: a plurality of suspension assemblies, each assembly including a top housing having means to receive thereon the sub-chassis; rod means extending vertically through each housing; spring means having one end suspended from the rod means; and vibration absorbent means having one portion supported at the lower end of the spring means and a second portion supporting the top housing for decoupling the spring means from the sub-chassis.
In one preferréd form of the present invention, the springs are effectively decoupled from the sub-chassis support housing by means of two different materials. The nylon housing support is the primary isolator between the springs and the floating assembly; however, it is further isolated from the spring housing top assembly (i.e. the sub-chassis support) by a layer of sponge rubber. The latter together with the nylon housing support effectively provide a barrier which blocks any vibration in the springs themselves from entering the sub-chassis. Furthermore, the sponge rubber also damps the spring housing top assembly and sub-chassis support. Still, the layer of sponge is effectively another "spring" that acts in conjunction (series) with the main spring but in the other direction:
the main spring acts in a downward direction by extension while the sponge spring acts in an upward direction by compression. The combination of these two modes in a dual action spring is very effective and once again makes a significant contribution to groove isolation. The present invention makes use of a spring support rod which pr~trudes-from the top of the spring housing making sub-chassis adjustment and levelling accessible from above, unlike other turn-tables which require removal of the bottom of the base, an extremely tedious and time consuming internal spring adjustment. Furthermore, conventional turntables of this type achieve their suspension adjustment by actually compressing and expanding the springs; this of course, ~131133 varies the tuning of the suspension in an unpredictable fashion. In the present turntable, rotation of the spring support rod to achieve levelling raises and lowers the entire spring assembly without compressing or expanding the springs. This of course, means that the suspension tuning is completely unaffected by suspension levelling.
THE SUB-CHASSIS
The present invention also relates to a sub-chassis for supporting a turntable of a phonograph record player which comprises a flat laminated structure having a plurality of arm extensions adapted to be engaged with and supported by suspension assemblies associated with the turntable; the laminated structure includes a plurality of layers of metals interspaced by means of vibration absorbent bonding layers.
Audible characteristics which can be obtained from an improved turntable assembly made in accordance with the present invention are: improved clarity, increased dynamic range, lack of mid-bass boom, deep bass control and extension, improved transient response without any brittle emphasis, smooth and seamless balance, from low bass to extreme highs, precise image without exceptional f^cus, natural depth perspective, airiness, lack of locational smearing, and new standard of audibility of intertransient silence between notes.
- Other objects and scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that this description, while indicating pref~rred embodiment of the invention, is given by way of illustration only since various changes and modifi-cations within the spirit and scope of the invention will become apparent to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a turntable ~ ~L31133 g assembly made in accordance with the present invention, some components not essential to the present invention having been omitted for clarity purposes;
Figure 2 is a top elevational view of the turntable assemb'y shown in Fig. l;
Figure 3 is an elevational, partly cross-sectional, view taken along lines 3-3 of Fig. 2;
Figure 4 shows a variant of the spacer means shown in Fig. 3; and Figure 5 shows a variant of the vibration absorbent means used in the suspension assembly illustrated in Fig. 3.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figs. 1-3, there is shown a turn-table assembly displaying the essential components of the present invention. Generally, the turntable includes a base 10 having at the rear two vertically extending hinge plates 12 to which is pivotally mounted a cover 14. The front portion of the base 10 also includes a plate 16 on GU which rests the front portion of the cover 14. This provides to the turntable assembly, when the cover is in the closed position, an aerated appearance since the cover is at a distance from base 10. The base plate 10 and the cover 14 are preferably made of a plastic material, such as acrylic.
The turntable assembly further includes a sub-chassis 18 having a large surface area and a series of projections that include three arm extensions 20, 22 and 24, one tone arm extension 26 and one spirit level extension 28. The three arm extensions 20,22,24 each include a circular opening so as to rest on and engage suspension assemblies 30,32 and 34, respectively.
The turntable assembly includes a platter 35 for receiving and the playing of a phonograph record 38 by means of a pick-up 36; the record has a grooved playing area 40 and a label area 42 (see Fig. 3). The l33 record extends over a mat 46, except for its peripheral edge, the mat resting on the top face of platter 35.
The platter 35 is centrally supported on a spindle 48 having a shoulder 50 on which the platter sits. The lower portion of the spindle 48 is received in a bearing assembly 52 which has its lower portion protruding through an opening 54 in the base plate 10.
A cone-shaped member 56 extends over the record and is connected to the spindle by means of a knob member 58 which is threadedly engaged with the upper portion of the spindle 48. The knob is engaged to the cone-shaped member by means of a spring clip 59 at the lower part of the knob stem. A small ring 60 is disposed to raise the record centrally thereof; in the embodiment shown, the ring is located between the record and the mat and is of a size so as to be confined within the label area of the record. It will be evident that the raising function could also be performedby a spacer ring located between the mat and the platter 35 or still simply by a raised portion in the construction of the mat 46 or of the platter 35. In one variant such as illustrated in Fig. 4, spacer 60 is tapered to assist in the suction effect between mat and record.
A more detailed description of each component will now be given together with a description of its role in reducing vibration which is ordinarily transmitted to th~ stylus of the tone arm in presently known systems.
One important feature of the present invention is the elimination of vibration transmitted by the record itself to the stylus. The peripheral edge 62 of the cone-shaped member 56 contacts the record 38 at about the periphery of the label area 42 of the record. By rotating knob 58 on the spindle, pressure is exerted on the record 38 which is raised centrally by the spacer 60. The appli-cation of an even force on the label area edge of the record against the central support member 60 forces the entire playing surface, i.e. the groove area 40 of the record, against the mat 46. The record 40 actually adheres to the mat through suction since a vacuum is created under the disc by the pressure exerted. The mat should therefore be flat without sculpted ridges in order that no air pockets be trapped under the disc;
these air pockets would themselves resonate and would excite the vinyl above them. The mat should also be made of a material which clamps with vinyl to absorb vibrations in the vinyl before they may be retransmitted to the stylus. The mat is made slightly smaller in diameter than the disc in order that the raised lip 64 of the record does not raise the outer portion of the disc into the air. As a result, the entire grooved surface of the disc is forced through the pressure applied against the elasticity of the vinyl into intimate contact with the mat. As indicated above, this results in damping the vinyl resonances themselves, in eliminating the vinyl as a storage medium, in preventing the transmission of accoustic energy by the vinyl to the stylus and in elimi-nating practically all warps.
The cone-shaped member includes a plurality of openings 65 to allow air circulation under the cone to prevent air from being trapped underneath.
The platter 35 of the turntable should be precision machined and preferably made of a magnesium-aluminum alloy which combines rigidity and strength. It is designed as a fly-wheel with the majority of the mass distributed around the peripheral edge 44 such as shown in Fig. 3; the momentum of the rotating fly-wheel overcomes the flutter induced in a turntable by the stylus playing
2 transient. When the stylus traverses a large transient, the force generated is great enough to slow a light platter down momentarily; a servo control is of no use for this kind of flutter, since it corrects after the error has occurred.
11311~3 Turntables made of metal and having a large surface area are prone to resonances and mechanical vibration. The platter of the present invention, contrary to known systems which use the mat to damp the platter, is preferably provided on its side wall with a pair of parallel peripheral grooves in which are inserted bands 66,68 made of elastic sponge compound which act as a wave trap for any vibration travelling through the metal of the platter. These bands, together with the alloy used, result in a platter that is less resonant than presently known systems. It will be evident that similar results can be achieved with a platter provided with one or more than two grooves filled with sponge rubber or any damping material.
The turntable includes an inner flange portion 70 which is engaged by the pulley 72 connected to a motor (not shown) mounted on base plate lO.
Spindle 48 is made of a high strength steel precisely machined to within a given tolerance and with O a special chrome surface treatment that results in an extremely good hardness rating of approximately 70 Rockwell. The lower edge of the spindle has a circular opening into which is tight fitted a spherical tip 74 whlch preferably consists of tungsten carbide, which is an extremely hard material. The spherical tip 74 rests on a thrust pad 76 made of wear resistant extremely hard (approximately 93 Rockwell) ceramic material such as the one known under the trademark Amlox-68, as there must be absolutely no "give" in this part of the turntable. As explained above, if the thrust pad were to flex, then a ve-~ical motion on a very small scale of the entire pla~ter would result and the stylus would read this as a subsonic signal (rumble). The combination of a carbide tip and a ceramic thrust pad greatly reduces wear conditions in the thrust pad. Spindle 48 is mounted in its lower portion in a cylindrical thrust casing 78 1131~33 which is press fitted or otherwise mounted in the sub-chassis 24 and which has an upper flange portion resting on the top face of the sub-chassis. This lower portion of the spindle is maintained in vertical alignment inside the thrust casing 78 by means of a pair of bushings 80,82 preferably made of nylon. If a self-lubricating nylon is used such as the one known under the trademark OILON-PV-80, friction is almost non-existent which is most important in reducing the load on the motor as well as insuring smooth rotation of the spindle in the bearing.
This material, in exactly the opposite fashion to a normal bushing, does not create noise but actually absorbs and dissipates into the sub-chassis any vibration that may be created by the rotational process. This vibration absorption contributes significantly to groove isolation since it is helping to keep extraneous mechanical vibrations from getting to the record and, therefore, the stylus. Another property of this type of bushing is that it is self-lubricating.
The thrust pad 76 can be replaced, if required, by removing the bottom end wall 77 which is secured to the casing by means of screws 79.
The suspension component of the turntable ~s^m.bly will be described with reference to suspension assembly 34 shown in Fig. 3; however, it should be understood that the other two suspension assemblies 30 ar.d 32 will have the same structure and characteristic features. Suspension assembly 34 includes a spring housing having a top part 100 of inverted cylindrical shape having an opening 102 at its upper wall for access therethrough of the stem portion 110 of an adjustment knob 104 which is threadedly engaged to a threaded rod 106. The outside wall of the top housing 100 has a shoulder portion 108 on which is supported the sub-assembly extension 24. The stem portion 110 has an enlarged lower portion 112 on which rests a nylon ring 114.
13L3113;3 A spring 116 has its upper end supported on the nylon ring 11~ and its lower end receiving a second nylon ring 118. Spring 116 is bell-shaped in that it comprises a top portion with turns of small diameter, an intermediate portion in which turns only slightly increases in diameter toward the bottom, and a lower portion in which turns considerably taper outwardly and on which sits the nylon bushing 118. The particular shape given to the spring prevents a build-up in the frequency resonance which is characteristic of a cylindrically-shaped spring or a lack of linearity which is characteristic of a conically-shaped spring.
In another embodiment as illustrated in Fig. 5, a rubber ring 120 is provided between a nylon support 121 and the inside shoulder 122 of the spring housing 100.
This sponge rubber together with the nylon support effectively provides a barrier which blocks any vibration in the spring itself from entering the sub-chassis. The sponge rubber also damps the spring housing assembly and ~0 the sub-chassis support. Also, this layer of sponge is effectively another "spring" which acts in conjunction with the main spring, but in another direction: the main spring acts in the downward direction by extension, the sponge spring acts in an upward direction by compression.
The combination of these two modes contributes signifi-cantly to groove isolation.
-- - The lower portion of the spring support rod 106 is threadedly engaged-to a foot member 120 which is manually adjustable to level the base plate 10. Stem 106 also protrudes to the lower part 123 of the suspension hGu.,ing.
In one form of the invention, the sub-chassis 18 is a laminate structure formed of four layers 124 of a magnesium-aluminum alloy separated by three layers of a binding agent, such as epoxy, which is bonded to the metal layers under very high pressure resulting in an ~.~3113~
assembly which is rigid while at the same time being inert.
This is of great importance since the sub-chassis has a surface size which is prone to vibrations. This is controlled by the three inner bonding layers which act to decouple each of the four metal layers from each other and therefore act as barriers to vibration transmission.
These bonding layers also serve to absorb and dissipate vibration. The result is a sub-chassis with a very high rigidity while at the same time being very "dead". The geometry of the sub-chassis is of importance. The surface area must be minimized as much as possible since any large surface tends to act as a diaphragm while at the same time concentrating the majority of the mass around the bearing in order to absorb and dissipate any vibration from the bearing. In general, the mass distribution of the sub-chassis is very critical.
11311~3 Turntables made of metal and having a large surface area are prone to resonances and mechanical vibration. The platter of the present invention, contrary to known systems which use the mat to damp the platter, is preferably provided on its side wall with a pair of parallel peripheral grooves in which are inserted bands 66,68 made of elastic sponge compound which act as a wave trap for any vibration travelling through the metal of the platter. These bands, together with the alloy used, result in a platter that is less resonant than presently known systems. It will be evident that similar results can be achieved with a platter provided with one or more than two grooves filled with sponge rubber or any damping material.
The turntable includes an inner flange portion 70 which is engaged by the pulley 72 connected to a motor (not shown) mounted on base plate lO.
Spindle 48 is made of a high strength steel precisely machined to within a given tolerance and with O a special chrome surface treatment that results in an extremely good hardness rating of approximately 70 Rockwell. The lower edge of the spindle has a circular opening into which is tight fitted a spherical tip 74 whlch preferably consists of tungsten carbide, which is an extremely hard material. The spherical tip 74 rests on a thrust pad 76 made of wear resistant extremely hard (approximately 93 Rockwell) ceramic material such as the one known under the trademark Amlox-68, as there must be absolutely no "give" in this part of the turntable. As explained above, if the thrust pad were to flex, then a ve-~ical motion on a very small scale of the entire pla~ter would result and the stylus would read this as a subsonic signal (rumble). The combination of a carbide tip and a ceramic thrust pad greatly reduces wear conditions in the thrust pad. Spindle 48 is mounted in its lower portion in a cylindrical thrust casing 78 1131~33 which is press fitted or otherwise mounted in the sub-chassis 24 and which has an upper flange portion resting on the top face of the sub-chassis. This lower portion of the spindle is maintained in vertical alignment inside the thrust casing 78 by means of a pair of bushings 80,82 preferably made of nylon. If a self-lubricating nylon is used such as the one known under the trademark OILON-PV-80, friction is almost non-existent which is most important in reducing the load on the motor as well as insuring smooth rotation of the spindle in the bearing.
This material, in exactly the opposite fashion to a normal bushing, does not create noise but actually absorbs and dissipates into the sub-chassis any vibration that may be created by the rotational process. This vibration absorption contributes significantly to groove isolation since it is helping to keep extraneous mechanical vibrations from getting to the record and, therefore, the stylus. Another property of this type of bushing is that it is self-lubricating.
The thrust pad 76 can be replaced, if required, by removing the bottom end wall 77 which is secured to the casing by means of screws 79.
The suspension component of the turntable ~s^m.bly will be described with reference to suspension assembly 34 shown in Fig. 3; however, it should be understood that the other two suspension assemblies 30 ar.d 32 will have the same structure and characteristic features. Suspension assembly 34 includes a spring housing having a top part 100 of inverted cylindrical shape having an opening 102 at its upper wall for access therethrough of the stem portion 110 of an adjustment knob 104 which is threadedly engaged to a threaded rod 106. The outside wall of the top housing 100 has a shoulder portion 108 on which is supported the sub-assembly extension 24. The stem portion 110 has an enlarged lower portion 112 on which rests a nylon ring 114.
13L3113;3 A spring 116 has its upper end supported on the nylon ring 11~ and its lower end receiving a second nylon ring 118. Spring 116 is bell-shaped in that it comprises a top portion with turns of small diameter, an intermediate portion in which turns only slightly increases in diameter toward the bottom, and a lower portion in which turns considerably taper outwardly and on which sits the nylon bushing 118. The particular shape given to the spring prevents a build-up in the frequency resonance which is characteristic of a cylindrically-shaped spring or a lack of linearity which is characteristic of a conically-shaped spring.
In another embodiment as illustrated in Fig. 5, a rubber ring 120 is provided between a nylon support 121 and the inside shoulder 122 of the spring housing 100.
This sponge rubber together with the nylon support effectively provides a barrier which blocks any vibration in the spring itself from entering the sub-chassis. The sponge rubber also damps the spring housing assembly and ~0 the sub-chassis support. Also, this layer of sponge is effectively another "spring" which acts in conjunction with the main spring, but in another direction: the main spring acts in the downward direction by extension, the sponge spring acts in an upward direction by compression.
The combination of these two modes contributes signifi-cantly to groove isolation.
-- - The lower portion of the spring support rod 106 is threadedly engaged-to a foot member 120 which is manually adjustable to level the base plate 10. Stem 106 also protrudes to the lower part 123 of the suspension hGu.,ing.
In one form of the invention, the sub-chassis 18 is a laminate structure formed of four layers 124 of a magnesium-aluminum alloy separated by three layers of a binding agent, such as epoxy, which is bonded to the metal layers under very high pressure resulting in an ~.~3113~
assembly which is rigid while at the same time being inert.
This is of great importance since the sub-chassis has a surface size which is prone to vibrations. This is controlled by the three inner bonding layers which act to decouple each of the four metal layers from each other and therefore act as barriers to vibration transmission.
These bonding layers also serve to absorb and dissipate vibration. The result is a sub-chassis with a very high rigidity while at the same time being very "dead". The geometry of the sub-chassis is of importance. The surface area must be minimized as much as possible since any large surface tends to act as a diaphragm while at the same time concentrating the majority of the mass around the bearing in order to absorb and dissipate any vibration from the bearing. In general, the mass distribution of the sub-chassis is very critical.
Claims (19)
1. In a turntable assembly, - a spindle;
- a platter mounted for rotation on said spindle;
- a mat on said platter for receiving thereon a phonograph record having, on upper and lower faces thereof, a label area and a grooved playing area to be engaged by a phonograph stylus;
- means located beneath said record and confined within the label area of said record to raise said record centrally thereof;
- means mounted on said spindle over the record for applying pressure on the peripheral edge of said label area on the top face of said record to thereby force the grooved playing area of said lower face in suction contact with said mat whereby vibrations in the record may be transmitted to the mat rather than to the stylus.
- a platter mounted for rotation on said spindle;
- a mat on said platter for receiving thereon a phonograph record having, on upper and lower faces thereof, a label area and a grooved playing area to be engaged by a phonograph stylus;
- means located beneath said record and confined within the label area of said record to raise said record centrally thereof;
- means mounted on said spindle over the record for applying pressure on the peripheral edge of said label area on the top face of said record to thereby force the grooved playing area of said lower face in suction contact with said mat whereby vibrations in the record may be transmitted to the mat rather than to the stylus.
2. In a turntable assembly as defined in Claim 1, wherein said pressure applying means include a cone-shaped member having a peripheral edge contacting said peripheral edge of the label area of said record.
3. In a turntable assembly as defined in Claim 2, wherein said cone-shaped member includes a centrally located knob threadedly engaged to said spindle at one end thereof for adjusting the pressure of said record of said mat.
4. In a turntable as defined in Claim 1, wherein said means to raise said record centrally comprises spacer means between said record and said mat.
5. In a turn-table as defined in Claim 4, wherein said spacer means is tapered.
6. In a turntable assembly as defined in Claim 2 or 3, wherein said cone-shaped member is provided with openings to allow air circulation through said member and over said top face of said label area.
7. In a turntable assembly as defined in Claim 1, wherein said platter has a peripheral rim; groove means provided on said peripheral rim and a vibration absorbent material in said groove means acting as a wave trap for vibrations travelling through said platter.
8. In a turntable as defined in Claim 7, wherein said platter is machined from a magnesium and aluminum alloy.
9. In a turntable assembly as defined in Claim 7, wherein said vibration absorbent material consists of an open cell sponge rubber.
10. In a turntable assembly as defined in Claim ? further comprising a base plate; suspension means mounted on said base plate; a sub-chassis supported on said suspension means; a bearing supported on said sub-chassis, said bearing including a casing receiving a portion of said spindle for rotation therein.
11. In a turntable assembly as defined in Claim 10, a thrust pad of hard wear resistant material at the bottom of said casing; said lower portion of said spindle having, at its lower extremity, a spherical tip supported on said thrust pad, said tip being made of a hard wear resistant material.
12. In a turntable assembly as defined in Claim 11, wherein the material of said pad is ceramic and that of said tip is tungsten carbide.
13. In a turntable assembly as defined in Claim 10, wherein said suspension means comprises a housing formed of an upper part and of a lower part separated from one another, said sub-chassis being suspensed on said upper part; rod means extending through said suspension housing and said base plate;
spring means having one end supported on said rod means and the other end supporting said upper part.
spring means having one end supported on said rod means and the other end supporting said upper part.
14. A turntable assembly as defined in Claim 13, comprising vibration absorbent means between said other end of said spring means and said upper part of said suspension housing.
15. In a turntable assembly as defined in Claim 14, wherein said vibration absorbent means comprises a nylon support mounted on the other end of said spring means and a layer of sponge rubber between said nylon support and said upper part of said sus-pension housing; said spring means acting in a downward direction by extension, said sponge rubber acting in an upward direction by compression.
16. In a turntable assembly as defined in Claim 14, wherein said other end of said spring means has an outwardly flaring shape and wherein the diameter of said spring means at said one end is smaller than the diameter of said spring means at said other end; said nylon support having an inner peripheral edge portion which is tapered to correspond to said flaring shape of said other end of said spring means.
17. In a turntable assembly as defined in Claim 13, wherein said rod means include means thread-edly mounted thereon to adjust the height of said upper part of said housing to level said sub-chassis.
18. In a turntable assembly as defined in Claim 13, wherein said rod means has a threaded portion extending below said base plate and threadedly engaging foot means to adjust the height of said base plate.
19. In a turntable assembly as defined in Claim 10, said sub-chassis being formed of a laminate structure including a plurality of layers of magnesium-aluminum alloy separated by layers of a bonding agent to form a unitary structure which is rigid and inert;
said bonding layers acting to decouple each of said alloy layers from each other and to act as barriers to vibration transmission.
said bonding layers acting to decouple each of said alloy layers from each other and to act as barriers to vibration transmission.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA339,817A CA1131133A (en) | 1979-11-14 | 1979-11-14 | Turntable assembly |
| GB8029093A GB2063547B (en) | 1979-11-14 | 1980-09-09 | Turntable assembly |
| JP14639980A JPS5671804A (en) | 1979-11-14 | 1980-10-21 | Turn table |
| CA000403809A CA1155066A (en) | 1979-11-14 | 1982-05-26 | Suspension system for turntable |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA339,817A CA1131133A (en) | 1979-11-14 | 1979-11-14 | Turntable assembly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1131133A true CA1131133A (en) | 1982-09-07 |
Family
ID=4115609
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA339,817A Expired CA1131133A (en) | 1979-11-14 | 1979-11-14 | Turntable assembly |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5671804A (en) |
| CA (1) | CA1131133A (en) |
| GB (1) | GB2063547B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2120443A (en) * | 1982-03-05 | 1983-11-30 | Eklund Trading Aps | Gramophone turntable apparatus |
| DE3515059A1 (en) * | 1984-05-11 | 1985-11-14 | Hewlett-Packard Co., Palo Alto, Calif. | DEVICE FOR FIXING A STORAGE DISK IN A DISK STORAGE DEVICE |
| DE3514164A1 (en) * | 1985-04-19 | 1986-10-23 | Deutsche Thomson-Brandt Gmbh, 7730 Villingen-Schwenningen | ELASTIC BEARING WITH ADJUSTABLE DAMPING FOR RECORD PLAYERS |
-
1979
- 1979-11-14 CA CA339,817A patent/CA1131133A/en not_active Expired
-
1980
- 1980-09-09 GB GB8029093A patent/GB2063547B/en not_active Expired
- 1980-10-21 JP JP14639980A patent/JPS5671804A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2063547A (en) | 1981-06-03 |
| JPS5671804A (en) | 1981-06-15 |
| GB2063547B (en) | 1983-09-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |