Abstract:
A pickup arm driving control system in record disc players with repeat playback function. The driving control system can drive the manipulation of a tone arm in such a manner that only an optionally selected portion is repeatedly reproduced. The system includes an encoder for producing an output pulse at every predetermined step of the moving of the tone arm, a circuit for calculating the moving distance of the tone arm from an arm rest position by accumulating the output pulses, an operation switch for generating setting signals in response to manual operations conducted when the tone arm is just tracking the starting and end positions of a repeat playback part of the loaded record disc, a memory for storing the up-dated one of the calculated result of moving distance as a first memory value, the first memory values upon the generation of the setting signals as a second and third memory values, and a circuit for in response to the coincidences between the first memory value and the second or third memory value controlling the manipulation of the tone arm.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to pickup arm driving apparatus and, more particularly, to a pickup arm driving control system in record disc players with repeat playback function. 
     2. Description of the Prior Art 
     Auto-repeat record players which can automatically repeat the playback operation are known in the prior art. Conventionally, auto-repeat players repeatedly play back the full recorded surface on one side of a record disc. That is, it has been impossible in such record disc players to repeatedly play back an optionally selected part of the loaded record disc. While, there will be an occasion where an user requires to play back only a part of a loaded record disc recording some music or information to which he like to listen. Any heretofore known auto-repeat record disc player could not meet such user&#39;s requirement. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a novel pickup arm driving control system in record disc players capable of repeatedly playing back a part of a loaded record disc set or directed by an user without using recording-break portion detecting sensors or the like. 
     In accordance with the above object, the present invention is addressed to a pickup arm driving control system which comprises means for producing an output signal at every predetermined step of the moving of a tone arm, means for calculating the moving distance of the tone arm from a reference position at every output signal by accumulating said output signals, means for generating a first setting signal in response to a manual operation conducted when the tone arm is just tracking the start position of a part of the loaded record disc where an user wants repeat playback operation and a second setting signal in response to another manual operation conducted when the tone arm is just tracking the end position of the above mentioned repeat playback part of the loaded record, a memory unit for successively storing the up-dated one of the calculated result of moving distance as a first memory value at a first address, the first memory value upon the generation of the first setting signal as a second memory value at a second address and the first memory value upon the generation of the second setting signal as a third memory value at a third address, means for generating a first coincidence signal when the first memory value coincides with the second memory value during the repeat playback operation mode and a second coincidence signal when the first memory value coincides with the third memory value while the repeat reproduction for the above mentioned part of the record disc is being executed, and means for in response to the first and second coincidence signals controlling the manipulation of the tone arm so that the repeat reproduction may begin from the start position determined by the generation of the first setting signal and terminate at the end position determined by the generation of the second setting signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein: 
     FIG. 1 is a perspective view of a linear tracking arm assembly applicable to the present invention. 
     FIG. 2 is a block diagram showing a pickup arm driving control system embodying the present invention. 
     FIG. 3 consisting of FIG. 3A and FIG. 3B is a flow chart showing the logic operation sequence of the system of FIG. 2. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     There is shown in FIG. 1 of the drawings main part of a linear tracking pickup arm mechanical assembly which is applicable to a pickup arm driving control system according to the present invention. Worm gear 1 with a horizontal center axis is mounted across mounting plates 2 and 3 in such a manner as to freely rotate about the horizontal center axis. Reversible motor 4 drives worm gear 1 in a forward or reversal rotation through pulley 5 and belt 6. Sliding table 7 is engaged with worm gear 1 so as to slide along worm gear 1 rotates and disc-like rotator plate 8 is fixed to the end portion of worm gear 1 so as to rotate together with the rotation of worm gear 1. Tone arm 10 is pivotally mounted on arm holder 9, which is secured to sliding table 7, so as to be freely turned in vertical planes making a right angle with the horizontal center axis of worm gear 1. An arm lifter (not shown in the drawing) pivotally turns tone arm 10 by a predetermined angle in a clockwise or counterclockwise. On one end of tone arm 10 is provided pickup cartride 11 and on the other end of tone arm 10 balancing weight 12. Guide rails 13 crossing from plate 2 to plate 3 guide sliding table 7 through rollers 14 projecting out of table 7. And also, mounting plate 2 is provided with rest position detecting means (not shown in the drawings), for example limit switch, which detects that tone arm 10 reaches the arm rest position and in response to the detection produces an output signal. In rotator plate 8, a plurality of slits are radially formed. As a photocoupler a light emitting element and a photodetecting element are positioned at the opposite sides of rotator plate 8. Rotator plate 8 and photocoupler 15 constitute rotary encoder 16 which produces output pulses, the number of which is proportional to the number of rotations of rotator plate 8. The rotation of reversible motor 4 in a forward mode causes sliding table 7 and tone arm 10 to travel toward mounting plate 3 and the rotation of motor 4 in a reversal mode causes sliding table 7 and tone arm 10 to travel toward mounting plate 2, that is the arm rest position. When a positive polarity input signal is applied to the afore-mentioned arm lifter, tone arm 10 is driven to pivotally turn in a vertical plate to the position where the stylus point of cartridge 11 abuts with the surface of a loaded record disc. Reversely, the arm lifter in response to the receipt of a negative polarity input signal pivotally turns tone arm 10 to the position where the stylus point lies apart from the surface of the loaded record disc. 
     System Architecture Description 
     A pickup arm driving control system embodying the present invention is illustrated in a schematic block diagram of FIG. 2. The illustrated system is arranged to controllably drive the pickup assembly of FIG. 1. Central processor unit (hereinafter referred to as CPU) 21, read only memory (ROM) 22, read and write memory (RAM) 23, clock pulse oscillator 24, input/output interface unit (I/O adaptor) 25 and operation board 26 constitute a microcomputer system. It will be easily understood that CPU 21, ROM 22, RAM 23, oscillator 24 and I/O adaptor 25 can be realized by making use of corresponding parts of one chip microcomputer. ROM 22 previously stores a predetermined program which serves to control the sequence operation of CPU 21, ROM 22, RAM 23 and I/O adaptor 25. As required, CPU 21 fetches this program from ROM 22 and decodes it to generate control signals. ROM 22 also stores data for available record disc sizes, for 30 cm diameter record disc, count a 1  of output pulses produced in rotary encoder 16 when tone arm 10 travels from the arm rest position to the position where the stylus point of cartridge 11 lies right above the most outside sound groove of the loaded record disc during the forward driving mode of reversible motor 4 and count a 2  of output pulses produced in rotary encoder 16 when tone arm 10 travels from the arm rest position to the position where the stylus point lies right above the most inside sound groove of the disc. As further data of record disc size, counts b 1  and b 2  as defined in the above for 17 cm diameter record disc also are previously stored in ROM 22. 
     Operation board 16 are provided with switch 26-1 for designating a record disc size in loading, switch 26-2 for directing the start of repeat operation and the end thereof, switch 26-3 directing play-cut operation and the like. When any one of switches on board 26 is depressed, an output signal associated with the depressed switch is transmitted through I/O adaptor 25 to CPU 21 and a processing directed by the depressed switch is executed. A control signal directing any one of forward rotation, stop or reverse rotation of reversible motor 4 is applied from CPU 21 through I/O adaptor 25 to motor driver 27. The rotation of motor 4 is driven by the output of driver 27 is a forward rotation mode, stop mode or reverse rotation mode. When tone arm 10 reaches the arm rest position, rest position arrival detector 28 produces an output signal which is in turn transmitted through I/O adaptor 25 to CPU 21. CPU 21 generates a signal for directing the turn of tone arm 10 in a vertical plane. This signal is applied through I/O adaptor 25 to the arm lifter. 
     Reversible motor 4 rotates worm gear 1 through belt 6 and pulley 5. The rotation of worm gear 1 is accompanied with the rotation of rotator plate 8 of rotary encoder 16. Rotary encoder 16 produces output pulses the number of which is proportional to the number of rotations of rotator plate 8. These output pulses are transmitted through I/O adaptor 25 to CPU 21 and counted therein. The count V of these pulses is stored in RAM 23. The count V is up-dated at every output pulses produced by rotary encoder 16. During the interval while reversible motor 4 is rotating under the forward rotation driving signal, the pulses are up-counted. During the interval under the reverse rotation driving signal, the pulses are down-counted. And when tone arm 10 reaches the rest position, CPU 21 in response to the output issued from rest position arrival detector 28 clears count V. Accordingly, count V corresponds to the distance from the tone arm rest position to the existing position of tone arm 10. 
     RAM 23 stores repeat operation start and end position data at predetermined addresses. When repeat switch 26-2 is depressed in such a manner as to direct the repeat operation start position, count V upon this depression of switch 26-2 (this count is hereinafter referred to as count C) is stored at an address in RAM 23. When repeat switch 26-2 depressed in such as amnner as to direct the repeat operation end position, count V upon this depression of switch 26-2 (this count is hereinafter referred to as count D) is stored at another address in RAM 23. CPU 21 makes a comparison between the current count V and the data count, that is count a 1 , a 2 , b 1 , b 2 , C or D, at a predetermined timing. According to the comparison resultant, CPU 21 provides moter driver 27, through I/O adapter 25, with a driving signal for directing forward rotation, stop or reverse rotation of reversible motor 4 and provides the arm lifter with a positive or negative polarity signal. 
     System Operation Description 
     A flow chart showing the logic sequence in the operation of the system arranged as shown in FIG. 2 is presented as FIG. 3. Steps in the sequence of the flow diagram are numbered 1-36 as shown in FIG. 3. The following description will be drawn along the flow in the diagram of FIG. 3. 
     Steps 1-11 (Playback Start Operation Sequence) 
     As a power switch is thrown, the microcomputer system enters on a running condition. It is examined as the first step whether or not tone arm 10 presently lies at the arm rest position. If yes, the system proceeds to a condition for waiting for a playback start signal originated by the depression of operation direction switch 26-3. If not, CPU 21 provides motor driver 27 with a reverse rotation driving signal so that the reverse rotation of motor 4 may move tone arm 10 to the arm rest position in a fast reversal driving mode. In response to the detection that tone arm 10 lies at the rest position, counts V, C and D in RAM 23 are cleared. As operation direction switch 26-3 generates the playback start signal, CPU 21 in response to the receipt of this signal provides motor driver 27 with a fast forward driving signal to drive motor 4 in a fast forward rotation mode so that tone arm 10 may move toward the center of a record disc (this moving direction is hereinafter referred to as forward direction) in a fast driving mode. Rotary encoder 16 generates output pulses as worm gear 1 rotates during the rotation of motor 4. These pulses are received by CPU 21 and counted therein. The count V is stored in RAM 23 and incrementedly up-dated at every pulse generated by rotary encoder 16. At every increment of count V, the current count V is compared with count a 1  or b 1  stored in ROM 22 according to the size of the loaded record disc. The record disc size has been designated by switch 26-1 before the user directs the start of playback. In the flow chart, the record disc size is designated as 30 cm diameter. Thus, CPU 21 can access an appropriate count data, in this case count a 1 , stored in ROM 22 according to the disc size designation. Disc size designation switch 26-1 can be replaced with for example an optical sensor mounted on tone arm 10 for detecting the outside peripheral edge of a loaded record disc. With this sensor, the size of a record disc loaded in the player can be determined by the count V at an instant when the optical sensor detects the outside peripheral edge of the record disc during the fast forward driving of tone arm 10. 
     When count V coincides with count a 1  during the fast forward-driving of tone arm 10, CPU 21 learns it from this coincidence that tone arm 10 reaches the position right above the most outside sound groove of the loaded record disc. At this instant, CPU 21 generates a stop signal to be applied to motor driver 27 to transiently stop motor 4 and also a positive polarity signal to be applied to the arm lifter. Then CPU 21 provides motor driver 27 with a normal forward driving signal. Accordingly, tone arm 10 transiently stops at the position where count V=count a 1 . The arm lifter turns tone arm 10 so that the stylus point of cartridge 11 is put down on the record disc. After that, tone arm 10 is moved in the forward direction at a normal speed, with the stylus point of cartridge 11 abutting on the record disc. Now, the recorded information in the record disc is sequentially reproduced from the most outside sound groove. While tone arm 10 is being moved, rotary encoder 16 keeps generating output pulses. CPU 21 increments count V at every pulse. During the forward driving of tone arm 10, CPU 21 executes a comparison at every increment of count V to examine whether the current count V coincides with count a 2  stored in ROM 22 and with counts C and D stored in RAM 23. On the way of playback, when tone arm 10 reaches the start position of a part at which the user wants repeat playback, repeat switch 26-2 is depressed by the user. 
     Steps 12-29 (Repeat Playback Operation Sequence) 
     CPU 21 in response to an output signal produced by this first time depression stores at a predetermined address in RAM 23 count V upon the depression of repeat switch 26-2 as a start position data of repeat playback operation. As aforementioned, this count V is referred to as count C. Irrespective of the above repeat playback start position setting, the moving of tone arm 10 is kept and the reproduction continuously goes forward. Subsequently, when tone arm 10 reaches the end position at which the user requires to terminate the repeat playback operation, repeat switch 26-2 is depressed once again. CPU 21 in response to the second time depression on switch 26-2 stores at another address in RAM 23 count V upon the second time depression of switch 26-2, which is referred to as count D. At the same time of setting up the end position of repeat playback operation in the above manner, CPU 21 provides motor driver 27 with a stop signal to stop reversible motor 4. Successively, CPU 21 provides the arm lifter with a negative polarity signal to lift up tone arm 10 and also drives it at a fast speed through the fast reverse rotation of motor 4 so that tone arm 10 is moved toward the outside of the record disc (this direction is referred to as a reversal direction). CPU 21 decrements count V at every pulse generated from rotary encoder 16 during the reversal driving of tone arm 10. When tone arm 10 returns to the rest position, CPU 21 in response to the output signal produced by reset position arrival detector 28 rotates through motor driver 27 reversible motor 4 in the fast forward rotation mode. CPU 21 clears count V upon the situation of tone arm 10 at the rest position and in turn increments it at every pulse from rotary encoder 16 as tone arm 10 travels in the forward direction again. It will be understood that the above clearance of count V can be omitted from the operation sequence in case that count V decrements to zero when tone arm 10 arrives at the rest position. 
     During the fast forward moving of tone arm 10, when the incremented count V coincides with count C stored in RAM 23 as the start position data of repeat playback operation, CPU 21 in response to this coincidence provides motor driver 27 with a stop signal and also the arm lifter with a positive polarity signal. Subsequently, CPU 21 provides motor driver 27 with a normal forward driving signal. As a result of the control by CPU 21, tone arm 10 transiently stops at the position where count V=count C, that is the start position of repeat playback operation, pivotally turns on arm holder 9 so that the stylus point of cartridge 11 may be put down on the record disc and then moves in the forward direction at the normal speed. Hereafter, the reproduction begins from the repeat playback start point set up through the first time depression of switch 26-2. On the way of this repeat playback, when count V coincides with count D stored in RAM 23 as the end position data of repeat playback operation, CPU 21 in response to this coincidence provides motor driver 27 with a stop signal to stop motor 4 at the end of repeat playback operation directed by the second time depression of repeat switch 26-2, the arm lifter with a negative polarity signal to lift up tone arm 10 so that the stylus point of cartridge 11 may lie apart from the record disc and then motor driver 27 with a fast reverse rotation signal to rotate motor 4 in a fast reversal mode so that tone arm 10 may be driven to the arm rest position. The next operation after tone arm 10 has arrived at the rest position returns to the starting step of repeat playback sequence. In this manner, the reproduction only for the selected part of a record disc is repeated. If the user want to stop the executing playback after step 28, he will depress operation direction switch 26-3 to generate an output signal which is interpreted as a cut signal in CPU 21 according to the program stored in ROM 22. In response to the cut signal, the operation sequence deviates from the repeat playback operation loop and goes to step 32 from step 29. Accordingly, tone arm 10 returns to the arm rest position. 
     Provided that during the playback operation the second time depression of repeat switch 26-2 has not been made until tone arm 10 reaches the most inside sound groove of the loaded record disc, CPU 21 will detect the coincidence between count V and count a 2 . In this case, the operation sequence branches at step 14 and goes to step 17. CPU 21 stores count 92 at a predetermined address in RAM 23 as count D to set up D=a 2 . After that, the branch returns to the stem sequence at step 18. This operation is the same manner as a case where the second time depression of repeat switch 26-2 is made when count V reaches count a 2 . Accordingly, if the second time depression of repeat switch 26-2 is not made during the playback, the repeat playback operation will be executed in a range from the starting position directed by the first depression of repeat switch 26-2 to the end of recording in the loaded record disc. 
     Steps 30-36 (Playback End Operation Sequence) 
     After starting the playback operation, where the first time depression of repeat switch 26-2 is not made, tone arm 10 continues moving to the end position of the loaded record disc without any transient stop. CPU 21 will detect the coincidence between count V and count a 2  at the end position of the loaded record disc. CPU 21 in response to this detection stops reversible motor 4, lifts up tone arm 10 and return it to the arm rest position in a fast reversal driving. When motor 4 arrives at the arm rest position, count V is cleared. CPU 21 becomes a condition of waiting for a signal produced by operation direction switch 26-3. Thus, the repeat playback operation is not executed and the full one side of a record disc is reproduced. 
     Cut Operation 
     When a cut signal is originated by the depression of operation direction switch 26-3, CPU 21 in response to the receipt of the cut signal during the fast forward driving mode and the normal forward driving mode provides motor driver 27 with a stop signal, the arm lifter with a negative polarity signal and subsequently motor driver 27 with a fast reversal driving signal. Thus, tone arm 10 transiently stops, pivotally turns to the position where the stylus point of cartridge 11 can lie apart from the record disc and travels toward the arm rest position in the fast reversal driving mode. When tone arm 10 reaches the arm rest position, rest position detection device 28 generates an output signal. CPU 21 in response to the receipt of this signal stops motor 4 and becomes a condition of waiting for a signal from operation board 26. 
     Whenever the cut signal is generated, CPU 21 accepts it except the operation stages where tone arm 10 is placed at the rest position or is moved toward the rest position in the fast reversal driving mode. The executing program is interrupted by the cut signal and the program following the interrupt is an instruction sequence which performs the return of tone arm 10 from the current position to the rest position. On the flow chart of FIG. 3, the cut signal acceptance is illustrated only at step 26. It, however, should be noted that the cut signal can be accepted as an interrupt signal with the first priority during any operation except the fast reversal driving of tone arm 10. 
     In the foregoing repeat playback operation, it is required that tone arm 10 returns from the repeat playback end position to the arm rest position before the next repeat operation and then travels to the repeat playback start position. Instead of such a return manipulation of tone arm 10, CPU 21 can stop motor 4 when count V coincides with count C during the reverse driving of tone arm 10 toward the outside of the record disc. Subsequently, CPU 21 puts down cartridge 11 on the record disc at the stop position and starts the next repeat reproduction. Since count V decrements at every output pulses of rotary encoder 16 during the fast reverse driving of tone arm 10, tone arm 10 is correctly placed at the start position of repeat reproduction without returning arm 10 to the arm rest position. 
     With the above mentioned pickup arm driving control system wherein tone arm positions corresponding to repeat playback start and end positions are memorized during the first time playback through manual operation by an user and then in the next time playback the current tone arm position is compared with the memorized tone arm position data to automatically determine the start and end positions of repeat playback, only the part of a loaded record disc where the user likes the listen is repeatedly reproduced. 
     As one of the features, the system does not require recording-break portion detecting sensors or the like the execute the above repeat operation. 
     As another of the features, an user can easily set up any position of a loaded record disc as the start and end positions of repeat playback while he is listening to the reproduced information like music, instead of previously giving a concrete data of repeat playback for the loaded record disc to the system. 
     A program expressed in assembly language for MUCOM43 series by Nippon Electric Company Ltd., which serves to execute the operation sequence of FIG. 3, is shown in an attached Appendix. 
     It will be easily understood for those skilled in the art that the present system is applicable the turning tracking arm assemblies as well as linear tracking arm assemblies. Since certain other changes also may be made in the above-described pickup arm driving control system without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the acompanying drawings shall be interpreted as illustrative and not in a limiting sense. ##SPC1## ##SPC2## ##SPC3##