Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
  • G11B15/18—Driving; Starting; Stopping; Arrangements for control or regulation thereof
  • G11B15/44—Speed-changing arrangements; Reversing arrangements; Drive transfer means therefor
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
  • G11B15/18—Driving; Starting; Stopping; Arrangements for control or regulation thereof
  • G11B15/26—Driving record carriers by members acting directly or indirectly thereon

Definitions

• the present invention relates to a cassette tap drive system for multi-speed cassette recorders which can b switched from a normal cassette speed to a slower spee suitable for voice recording and playback. More specifi cally, the subject invention relates to a drive mechanis for a multi-speed cassette recorder which enables adjustment to a very slow speed of approximately one-fourth or less of the standard cassette speed of 4.76 mm per second, utilizing a standard drive motor with speed at less than approximately 700 rpm.
• multi-speed cassette recorders have been developed which combine both standard and slow-speed functions.
• Standard tape speeds are used for record or playback of music and other uses well-known for standard cassette use.
• the cassette player is adapted for switching to a slow speed where only speech quality is required.
• An example of such a multi-speed cassette recorder is shown in U. S. Patent No. 4,215,377 by the same inventor and entitled "Multi-Speed Tape Cassette System.”
• This recorder embodies the use of the standard cassette speed of 4.76 mm per second and includes a switch for reducing tape speed by a factor of one-fourth. The resulting capacity of a standard cassette tape is thereby quadrupled merely by virtue of the speed reduction.
• the two-speed cassette player operated at approximately 3,000 rpm to give linear tape drive of 4.76 mm per second.
• the motor speed was then reduced by one-fourth to 750 rpm to provide a corresponding quarter speed cassette tape movement.
• the solution to achieving slow speed cassette playback of speech quality was initially accomplished by avoiding the non-operational range of appro ⁇ ximately 600 rpm. Instead, motor speed was increased to overcome this failing and thereby enable development of a single pulley drive on a capstan in a conventional tape drive format.
• the conventional mechanical system for driving economy-type cassette recorders is illustrated in U. S. Patent No.
• the cassette tape drive system comprises a motor with a pulley which transfers the rota ⁇ tional motion from the motor to a capstan drive assembly.
• a typical configuration for the capstan drive assembly is a shaft with a tape drive disc or roller which contacts the cassette tape and moves the tape at the rate of speed of the rotating face of the capstan roller. Tape movement is accomplished by trapping the cassette tape against the capstan drive roller by a pinch roller which prevents tape slippage when properly engaged.
• the cassette tape is pulled at the same speed.
• the rotational speed of the capstan roller is converted to linear speed in the tape movement prior to contact by tape recording, playback, or erase heads.
• the capstan assembly includes a fly ⁇ wheel which is mounted on the capstan to stabilize rota ⁇ tional movement as developed by the driving motor.
• a fly ⁇ wheel which is mounted on the capstan to stabilize rota ⁇ tional movement as developed by the driving motor.
• capstan assembly and other moving parts which may be coupled to the pulley of the moto represent a substantial load for the drive motor. Further ⁇ more, it is apparent that the operation of the cassett player in both normal and slow speed modes is clearly 5 dependent upon motor operation.
• motor speed has been regulated by electronic control circuitry to adapt the typical cassette recorder for slow speed operation.
• Numerous variations of motor speed control circuitry exist within the ° state of the art and develop a corresponding variance to the price range of consumer products of this type.
• Such electro ⁇ nic regulation generally tends to increase the price of the recorder beyond that which the consumer is willing to pay and consequently discourages the use of a single cassette _5 player for both record and playback function.
• a cassette tape, recorder and playback device having a single pulley cassette tape drive system including a variable speed control switch for continuously adjusting cassette tape drive speed from a range of approximately .80 millimeters per second to 1.15 millimeters per second.
• a cassette tape recorder and playback device which conforms to an economy line of cassette recorders designed for voice reproduction at extremely slow speeds which substantially extend the record and playback capability with respect to record and playback time.
• the device includes at least one record/playback head for applying or detecting magnetic signals on a cassette tape and at least one erase head for cancelling the signal.
• a conventional mechanical .shifting device is utilized for contacting the respective record/ playback and erase heads at the active surface of the cassette tape.
• the recording device includes electronic circuitry for interconversion of electromagnetic signals and audio output signals to provide record and playback capa ⁇ bility to the device.
• a -single pulley, cassette tape drive system is provided with a conventional electric motor which typically carries limiting operational characteristics wherein the tape drive system develops non-unifor tape movement leading to unsatisfactory levels of Wow and Flutter distortion and audio output when the drive system operates at motor output shaft rotation rates less than 700 rpm, and specifically in the approximate rate of 600 rpm.
• the cassette tape drive system is adapted for such slow-speed operation at rates less than 600 rpm by use of a balance flywheel integrally coupled to. the output motor shaft.
• the flywheel enables the cassette tape driv system to overcome non-uniform tape movement and improve audio output to an acceptable output signal suitable for vocal reproduction.
• the cassette tape recorder and playback device includes a single pulley drive belt for converting motor rotational motion to linear cassette tape movement against the record/playback and erase heads.
• Motor control elec ⁇ tronic circuitry is coupled to the tape drive system for applying a predetermined current to the motor to establish tape movement at a uniform rate less than 4.76 millimeters per second.
• the motor control circuitry and other electric power requirements are satisfied by a power source coupled to the system and motor electronic circuitry for enabling operation of the cassette recorder and playback device.
• Utilization of the subject invention enables oper- ation of an otherwise non-functional cassette tape recorder, where slow-speed operation at motor shaft rotation rates of less than 700 rpm would result in excessive levels of flutter and WOW distortion, making the cassette unit un ⁇ acceptable even for voice reproduction.
• a balanced flywheel coupled integrally, to the motor output shaft tape movement can be reduced to a range of .80 to 1.15 millimeters per second, enabling an increase of up to 5 times the standard tape time available from a cassette tape.
• the subject invention provides an additional alternative to the three previously listed options for obtaining acceptable slow-speed use for cassette tape voice reproduction systems.
• This fourth option has the benefit of minimal expense, maintenanc of minimal size for the tape recorder unit, minimal modification requirements to elec ⁇ tronic circuitry within the conventional cassette tape recorder design, and improved availability for commercial use to a broader range of markets.
• Figure 1 shows a perspective vi ⁇ *w of mechanical parts of the subject invention, with block-type diagram of electrical circuitry and related components.
• Figure 2 shows a side, plan view of the mechanical parts of the subject invention shown in Figure 1;
• Figure 3 is an enlarged view of the electric motor with the flywheel attachment shown in cross-section, mounted
• Figure 4 shows a graphical representation of operating characteristics of a conventional, low-cost motor commonly applied to the class of cassette tape recorders falling within the subject matter of the present invention.
• This type of motor is a low-input motor primarily operated on battery power source. It is typically used in audio mechanisms such as tape recorders, record players, and the like.
• the armature is three-pole and utilizes brushes and bearings for current flow. Such design is basic in the industry and is well-known
• the primary problem with low-speed operation (below 700 rpm) for the typical motor of this category is its lack of ability to maintain a uniform tape speed velocity.
• a standard cassette tape advances at 4.76 millimeters per second, and has sufficient speed to permit some motor speed variation without dis ⁇ torting audio output.
• the tape speed is reduced by a factor of four or more, for example to a speed of 1.0 millimeter per second, the low-cost motors jerk and create virtually inaudible audio output, unless other fac ⁇ tors - are introduced to increase torque or rpm speed of the motor.
• FIG. 1 show basic mechanical components of a cassette tape recorder, with electrical components in block diagram form. Th cassette tape 11 is shown with its direction of emplacemen within the cassette recorder coming from the bottom of th page. Although the normal orientation of the machine show in Figure 1 would be inverted such that the cassette would be inserted from the top, the subject figure is shown i opposite orientation to disclose the basic components of the cassette tape drive system.
• Figure 1 discloses a record/playback head 12 which is illustrated to be engaged against the cassette tape 13 wound on reels within the cassette body 14.
• a double track or stereo head may be utilized and switched for single track operation to double the available time for use.
• the tape speed was reduced to one-fifth the standard speed of 4.76 millimeters per second
• use of a stereo or dual track record/playback head in a single track mode doubles this one-fifth reduction in tape speed to yield available taping time of ten times the tape capacity in standard, stereo mode.
• an erase head 15 is provided and is appropriately wired to provide single or dual erase capacity for the respective tracks recorded on the tape 13.
• the re ⁇ cord/playback head 12 and erase head 15 are usually mechani ⁇ cally ganged with a rubber, compression roller 16 which operates to impress the cassette tape 13 against the capstan drive shaft 17.
• This mechanical combination 12, 15 and 16 is typically engaged against the cassette and tape by a mechanical lever 18 and associated hardware which enables the displacement of the respective heads and compression wheel into engagement of the cassette or retraction when not in use.
• levers are shown in common orientation with lever 18 and represent other well-known operating modes or switches, such as record, pause, rewind, etc.
• This mechanical hardware is not specifi- cally shown in the figures in view of its well-known nature to those skilled in the art.
• FIG. 1 shows the circuitry 20 coupled to the respective record/ playback and erase heads in a graphic manner via item 21.
• the circuitry is powered by a power source 2 coupled via circuit wires 23.
• This power source 22 typicall provides * power for motor control electronic circuitry 2 which maintains motor speed at appropriate levels as th tape recorder is switched from standard play to slow spee (.80 to 1.15 millimeters per second tape speed).
• Connecting wires 26 are graphic representations of circuitry coupling between the system electronic circuitry 20 and motor control circuitry 24. Such graphic representations are intended to cover conventional circuit arrangements for maintaining record and playback capability in standard and slow-speed operation. Therefore, further disclosure is deemed unneces ⁇ sary. * The primary focus of the subject invention is in connection with the cassette tape drive system comprised of an electric motor 30 having a rotary output shaft shown in dashed lines as item 31.
• cassette tape 13 is captured between the capstan shaft 17 and compression wheel 16.
• the rotation of the capstan drive wheel 34 causes common rotation of the capstan shaft 17, which thereby regulates tape movement across the respective record/playback 12 and erase 15 heads.
• the cassette reels 37 and 38 are powered by the single pulley 33 as it rotates drive wheel 38.
• This drive wheel 38 is coupled to a geared transmission wheel 39 which is capable of selectively engaging cassette drive wheels 40 and 41.
• the operation of this system maintains the cassette tape in a tense span from the respective cassette reels 37 and 38 across the capstan shaft 17, record/playback head 12, and erase head 15.
• the foregoing components have regularly been applied to standard speed and slow-speed cassette recorders. However, because of inadequate motor torque and efficiency, operation below 700 rpm and 1.2 millimeters per second tape speed has not been available.
• the present inventor has discovered that integral attachment of a balanced flywheel 50 to the motor output shaft 31 can convert the subject cassette recorder to an operable system suitable for vocal reproduction within the previously non-operable ranges. Accordingly, without modifi ⁇ cation of motor characteristics as represented in Figure 4, and without requirement of electronic circuitry modifica- tions such as increasing rotational speed of the motor to maximum levels, the unexpected and surprising results are achieved strictly by mechanical adaption.
• the flywheel applied to the motor output shaft 31 must have sufficient mass to develop a required inertial force necessary to complement, motor torque to develop an opera ⁇ tional system.
• This flywheel should be at least 15 grams in weight, and usually will not exceed 150 grams.
• the most preferred range of flywheel mass for the type of motor represented as used in Figure 1 is 20 to 40 grams. It is important that the flywheel be integrally coupled to the motor output shaft to ensure . no free movement of the flywheel independent of the motor shaft 31.
• the flywheel configuration 50 illustrated in the fi ⁇ gures includes its primary mass unit 51 and the drive belt reel 52.
• This reel may be composed of separate wall elements 52a and 52b on opposing sides of a belt drive surface 52c, or the combination can be substituted by a single element performing the same function.
• the mass unit 51 of the flywheel 50 may be of any weighted material such as brass or comparable metals.
• the specific weight of the mass unit 51 is best optimized by empirical evaluation of the specific motor utilized in the cassette recorder. For example, each motor of different manufacturer and design will have varying performance char ⁇ acteristics. Because of the extreme variation of motor efficiency in the range of 600 to 700 rpm, empirical derivation of optimum flywheel weight is necessary. Numerous methods are available within the state of the art for adjusting weight in a balanced flywheel and measuring audio output and other factors for optimization.
• the motor 30 is mounted to a cassette chassis 36, with appropriate spacing for proper tension on the pulley or drive belt 33.
• the drive belt 33 is mounted on reel 52 close to the axis of the motor output shaft 31 to enhance the maintenance of momentum with respect to the motor rotation. This is contrary to standard mounting techniques in connection with the drive belt on the capstan drive wheel 34. It has been noted by the inventor that such mounting techniques greatly enhance the ability of such a cassette unit to operate at low speeds, despite normal inoperability caused by only slight variations in rpm.
• a cassette recorder without the subject motor shaft flywheel developed .5 percent WO /Flutter at standard speed (4.76 millimeters per second). Without the flywheel attached, reduction of the motor speed by more than one-quarter (below 700 rpm) resulted in increased WOW/Flut- ter exceeding one percent.

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• Control Of Electric Motors In General (AREA)
• Recording Or Reproducing By Magnetic Means (AREA)

Applications Claiming Priority (1)

Publications (2)

Family

ID=22168218

Family Applications (1)

Country Status (4)

Citations (3)

Family Cites Families (3)

• 1982
  • 1982-09-23 EP EP19820903121 patent/EP0120838A4/de active Pending
  • 1982-09-23 JP JP50305182A patent/JPS59501645A/ja active Pending
  • 1982-09-23 WO PCT/US1982/001306 patent/WO1984001234A1/en not_active Application Discontinuation
  • 1982-09-23 AU AU89934/82A patent/AU8993482A/en not_active Abandoned

Patent Citations (3)

Non-Patent Citations (1)

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