POWER CONTROL DEVICE FOR DISK APPARATUS

Abstract: A power control device for a disk apparatus has first and second flip-flops (41, 43) respectively constituted by mono­ stable multivibrators for latching STEP and MOTORON signals supplied from a floppy disk controller (3) during execution of a seek instruction of a main processor (1). An output from the second flip-flop (43) is disabled before the STEP signal is supplied thereto. A period of time T2 for which a final STEP signal is supplied to the second flip-flop (43) and then the output from the first flip-flop (41) is disabled is longer than a pulse width of the STEP signal. Q outputs from the first and second flip-flops (41, 43) are supplied to first and second transistors (Q1, Q2) through a NOR gate (45). Collector outputs of the first and second transistors (Q1, Q2) are supplied to the bases of third and fourth transistors (Q3, Q4) whose emitters respectively receive voltages of +12 V and +5 V. An output from the NOR gate (45) is kept low for a predetermined period of time until the rush current is eliminated after the spindle motor (17) is started, and for a predetermined period of time after the step pulse is supplied to drive the stepping motor (13). The first and second transistors (Q1, Q2) are kept off and then the third and fourth transistors (Q3, Q4) are also kept off. Power supply voltages of +12 V and +5 V are not supplied to a read/write amp (11).

Description: The present invention relates to a disk apparatus with low power consumption. A conventional disk apparatus, e.g., a floppy disk system is illustrated in Fig. 1. Floppy disk drivers 5 and 7 for driving the floppy disk drive are connected to a floppy disk controller 3 and a main processor 1 through a floppy disk interface (not shown). The controller 3 controls the drivers 5 and 7 under the control of the processor 1 to perform data read/write access, serial/parallel conversion and CRC (Cyclic Redundancy Check). Fig. 2 is a detailed block diagram of a conventional floppy disk driver 5 (a similar control unit is described in JP-A-56134357). The driver 5 has a magnetic head 9, a read/write amp 11 for supplying a read/write signal to the head 9, a stepping motor 13 for driving a carriage having the head 9 thereon, a stepping motor driver 15, a spindle motor 17 for driving the floppy disk, a spindle motor driver 19, a power supply controller 21, a power supply switching circuit 23 and a controller 25 for controlling the above-mentioned components 11, 15, 19 and 21. The controller 25 controls the overall operation of the driver 5 in response to an interface signal supplied from the controller 3. The controller 25 comprises a random logic circuit constituted by TTL gates or a microprocessor controlled by a program. The controller 25 is connected to the controller 21. The controller 21 is connected to the circuit 23. The controller 21 controls power supply switching of the circuit 23. The circuit 23 supplies a plurality of power supply voltages 27 externally supplied under the control of the controller 21 to or stops supplying them to the driver 15, the motor 13, the driver 19 and the motor 17. At the same time, the circuit 23 switches different types of power supply voltages (e.g., +5 V and +12 V). The circuit 23 supplies the power supply voltage to the driver 19 and the motor 17 or stops supplying it thereto. On the other hand, the circuit 23 supplies the power supply voltage to the driver 15 and the motor 13 or stops supplying it thereto, and switches the different types of power supply voltages applied to the driver 15 and the motor 13. The selection of the power supply voltage applied to the driver 15 and the motor 13 by the circuit 23 is performed such that a DC +12 V voltage is applied to the driver 15 and the motor 13 when the motor 13 requires a high torque, but a DC +5 V voltage is supplied thereto when the motor 13 requires a low torque. The amp 11 directly receives the externally applied power supply voltage. In order to decrease power dissipation of the floppy disk driver 5 having the arrangement described above, the following implementation is utilized. A MOTORON signal is used as one of interface signals 29. The processor 1 can directly control driving of the motor 17 in response to the MOTORON signal. When the MOTORON signal is significant data, the controller 25 directly controls the controller 21, and the power supply voltage 27 is supplied from the circuit 23 to the driver 19 and the motor 17. However, when the MOTORON signal is not a significant signal, the power supply voltage is not supplied from the circuit 23 to the driver 19 and the motor 17. In this manner, when the processor 1 does not use the driver 5, the power supply voltage is not supplied to the driver 19 and the motor 17, thereby achieving lower power dissipation and hence decreasing heat dissipation. The two types of power supply voltages are selectively applied to the motor 13 in accordance with the operating mode. While the motor 13 is being operated, i.e., while a magnetic head seek is being performed, a high torque is required, so that the motor 13 receives a high voltage (i.e., 12 V). A period of time (generally called a "settling time") required for application of the high voltage is started when the head receives a seek instruction from the processor 1 and starts a seek operation (i.e., after a STEP PULSE as one of the interface signals is received) and is ended when the seek instruction is completely executed and the stepping motor is completely stopped. When the motor 13 is stopped, i.e., when the head 9 is positioned above a predetermined track, a low voltage (+5 V) is applied to the motor 13 since a low torque is required in order not to cause a positioning error of the head 9. When the processor 1 does not use the driver 5 and is held in the wait mode, the power supply voltage is not supplied to the driver 15 and the motor 13, thereby achieving low power consumption and decreasing heat generation. Figs. 3A through 3G are are timing charts of signals for explaining the power consumption state of the driver 5. Fig. 3A shows a change in total power dissipation, Fig. 3B shows an application state of the external power supply voltage 27, Fig. 3C shows a state of the MOTORON signal, Fig. 3D shows a seek operation, Fig. 3E shows a state of the power supply voltage applied to the motor 13, Fig. 3F shows a state of power consumption in the motor 17, and Fig. 3G shows a state of the power supply voltage applied to the amp 11. As is apparent from Figs. 3A through 3G, the power supply voltage 27 is always applied to the amp 11 irrespective of the operation mode of the driver 5, so that the amp 11 always consumes power and radiates heat. In particular, the voltage 27 is applied to the amp 11 when the motor 17 is started and while the seek operation is being performed. As a result, high power is consumed. It is an object of the present invention to provide a power control device in a disk apparatus having low total power consumption by preventing excessive power supply and averaging the power consumption. In order to achieve the above object of the present invention, there is provided a floppy disk apparatus comprising: a magnetic head for accessing a magnetic recording medium, generating a read signal in a data read mode and generating a write signal in a data write mode; a read/write amplifier for amplifying the read signal supplied from the magnetic head and the write signal supplied to the magnetic head; a power supply for supplying power to the read/write amplifier; and power supply control means for supplying power to the read/write amplifier while the read/write amplifier is operative and cutting off power supply to the read/write amplifier while the read/write amplifier is inoperative. According to a power control device for a disk apparatus of the present invention, the power supply voltage is not supplied to the read/write amp 11 except for a necessary period of time, thereby decreasing power consumption. A peak of the total power consumption can be eliminated, and the power consumption of the overall system can be averaged. As a result, heat generation can be decreased as a whole. Other objects and features of the present invention will be apparent from the following description taken in connection with the accompanying drawings, in which: Fig. 1 is a block diagram showing the system configuration of a conventional floppy disk apparatus; Fig. 2 is a detailed block diagram of a floppy disk driver shown in Fig. 1; Figs. 3A through 3G are respectively timing charts showing the power consumption state of the driver shown in Fig. 2; Fig. 4 is a detailed block diagram of the driver 5 according to an embodiment of the present invention; Figs. 5A through 5G are respectively timing charts for explaining the operation of the power control device in the disk apparatus of the present invention, in which Fig. 5A shows a total power consumption, Fig. 5B shows an external power supply voltage, Fig. 5C shows a MOTORON signal, Fig. 5D shows a seek operation state, Fig. 5E shows a power supply voltage applied to the stepping motor, Fig. 5F shows power consumption of the spindle motor, and Fig. 5G shows a power supply voltage applied to the read/write amp; Fig. 6 is a detailed circuit diagram of a controller shown in Fig. 4; and Figs. 7A through 7H are respectively timing charts for explaining the operation of the controller 31, in which Fig. 7A shows a MOTORON signal, Fig. 7B shows a STEP signal, Fig. 7C shows an output from a first flip-flop 41, Fig. 7D shows an output from a second flip-flop 43, Fig. 7E shows an output from a NOR gate 45, Fig. 7F shows a base voltage applied to transistors Q1 and Q2, and Figs. 7G and 7H respectively show +12 and +5 v power supply voltages applied to the read/write amp 11. A preferred embodiment will be described with reference to Figs. 4 through 7A to 7H. Fig. 4 is a block diagram of a floppy disk driver 30 according to an embodiment of the present invention. The same reference numerals in Fig. 4 denote the same parts as in Fig. 2. Referring to Fig 4, the driver 30 is controlled by a floppy disk interface signal 29 supplied from a floppy disk controller 3 under the control of a main processor 1. A read/write amp 11 amplifies read and write signals with respect to a magnetic head 9. A stepping motor 13 drives a carriage having the head 9 thereon. The motor 13 is driven by a stepping motor driver 15. A spindle motor 17 drives the floppy disk. The motor 17 is driven by a spindle motor driver 19. A controller 31 controls the overall operation of the driver 30. A power supply switching circuit 23 supplies +5 and +12 V power supply voltages 27 (when the driver 5 is incorporated in a personal computer system, for example, these voltages are those from the personal computer) externally supplied under the control of the controller 21 to or stops supplying them to the driver 15, the motor 13, the driver 19 and the motor 17. At the same time, the circuit 23 switches different types of power supply voltages (e.g., +5 V and +12 V). The circuit 23 supplies the power supply voltage to the driver 19 and the motor 17 or stops supplying it thereto. On the other hand, the circuit 23 supplies the power supply voltage to the driver 15 and the motor 13 or stops supplying it thereto, and switches the different types of power supply voltages applied to the driver 15 and the motor 13. The selection of the power supply voltage applied to the driver 15 and the motor 13 by the circuit 23 is performed such that a DC +12 V voltage is applied to the driver 15 and the motor 13 when the motor 13 requires a high torque, but a DC +5 V voltage is supplied thereto when the motor 13 requires a low torque. The controller 31 exchanges interface signals 29 with the controller 3 to perform decoding and execution of an instruction from the processor 1, a status acknowledgement to the processor 1, reception/transmission of data with respect to the amp 11, sending of the read/write instruction, start/stop control of the driver 19 for controlling the motor 17, and excitation phase control of the driver 15 for controlling the motor 13. In this manner, the controller 31 performs control of the overall system. The controller 31 comprises a random logic circuit of TTL gates or the like. However, the controller 31 may comprise a microprocessor controlled by a program. The power supply controller 21 controls the power supply switching circuit 23 under the control of the controller 31. The controller 21 causes the circuit 23 to supply a high voltage (DC +12 V) to the motor 13 while the head 9 performs a seek. However, when low torque is required, i.e., when the head 9 is located above a predetermined track, the controller 21 causes the circuit 23 to apply a low voltage (DC +5 V) to the motor 13. A power supply controller 33 controls operation of a power supply switching circuit 35 under the control of the controller 31. The circuit 35 selectively supplies the power supply voltages 27 under the control of the controller 33. Figs. 5A through 5G show the power dissipation state of the driver 30 shown in Fig. 4, in which Fig. 5A shows a change in total power dissipation, Fig. 5B shows a state of an application of the external power supply voltage 27, Fig. 5C shows a state of the MOTORON signal, Fig. 5D shows a state of seek, Fig. 5E shows a state of a power supply voltage applied to the stepping motor, Fig. 5F shows a state of power dissipation in the spindle motor, and Fig. 5G shows a state of the power supply voltage applied to the read/write amp 11. Fig. 6 is a detailed circuit diagram of the controller 31 shown in Fig. 4. A step signal STEP and a drive select signal DRIVE SELECT are supplied from the controller 3 to a 2-negative input AND gate 37. An output from the AND gate 37 is supplied to a stepping motor phase controller 39 and a first flip-flop 41. The controller 39 also receives a DIRECTION signal representing a rotational direction. The controller 39 supplies two phase signals A and B to the driver 15. The driver 15 supplies two phase signals to the motor 13 through A and B coils. The flip-flop 41 latches the output signal from the AND gate 37. The flip-flop 41 comprises a monostable multivibrator. A Q output signal from the flip-flop 41 is supplied to the circuit 23. The circuit 23 controls the power supply voltage supplied to the drivers 15 and 19. The signal MOTORON is supplied to a second flip-flop 43. The flip-flop 43 comprises a monostable multivibrator. The signal MOTORON is also supplied to the driver 19. Q outputs from the flip-flops 41 and 43 and the MOTORON signal are supplied to a NOR gate 45. An output from the NOR gate 45 is supplied to the bases of first and second transistors Q1 and Q2 serving as switches. The emitters of the transistors Q1 and Q2 are commonly grounded. The collector terminals of the transistors Q1 and Q2 are connected to the bases of transistors Q3 and Q4 through resistors, respectively. A voltage of +12 V is applied to the emitter of the transistor Q3, and a voltage of +5 V is applied to the emitter of the transistor Q4. The collectors of the transistors Q3 and Q4 are connected to the amp 11. The portion surrounded by the broken line is a peripheral LSI chip model No. T6677S available from TOSHIBA CORPORATION, Japan. The operation of the power control device for the disk apparatus having the system configuration according to the present invention will be described hereinafter. Implementation and operation of the device for decreasing power dissipation in the motors 13 and 17 are the same as in a conventional apparatus, and a detailed description thereof will be omitted. An operation for decreasing power dissipation for the amp 11 will be described hereinafter. The data read/write access with respect to the head 9 is performed when the following two conditions are satisfied: i) The motor 17 is rotated at a constant speed. In other words, the signal MOTORON is generated from the controller 3. ii) The motor 13 is stopped. In other words, the signal STEP is disabled. As is apparent from Fig. 5F, a rush current during starting of the motor 17 and high-voltage supply to the motor 13 causes a peak in total power dissipation. Under the control of the controllers 31 and 33, the circuit 35 stops supplying the power supply voltage 27 to the amp 11 for a predetermined period of time until the rush current disappears after the motor 17 is started, during the seek of the head 9, and until a predetermined period of time has elapsed after the final step pulse is supplied from the processor 1 to drive the motor 13. Until the floppy disk controller generates the MOTORON signal after the power supply voltage 27 rises, i.e., until the MOTORON signal is nonsignificant and is set at high level, the output of low level (Fig. 7E) is supplied from the NOR gate 45 to the bases of the transistors Q1 and Q2. As a result, the base potentials of the transistors Q1 and Q2 are set at 0 V, as shown in Fig. 7F. In this state, the transistors Q1 and Q2 are kept off. For this reason, the transistors Q3 and Q4 are also kept off. The voltages of +12 V and +5 V shown in Figs. 7G and 7H are not supplied to the amp 11. The controller 3 generates the MOTORON signal as shown in Fig. 7A in response to the instruction from the processor 1. The MOTORON signal is significant and is set at low level, as shown in Fig. 7A. The MOTORON signal is latched by the flip-flop 43, as shown in Fig. 7D. The Q output of high level from the flip-flop 43 is supplied to one input terminal of the NOR gate 45. The NOR gate 45 supplies the low level signal (Fig. 7E) to the bases of the transistors Q1 and Q2. The base potentials of the transistors Q1 and Q2 are set at 0 V, as shown in Fig. 7F, and the transistors are kept off. The transistors Q3 and Q4 are also kept off. Therefore, the voltages of +12 V and +5 V are not supplied to the amp 11, as shown in Figs. 7G and 7H. The Q output from the flip-flop 43 is disabled when a predetermined period of time (i.e., time T1) has elapsed. The Q output of low level from the flip-flop 41 and the Q output of low level from the flip-flop 43 are supplied to the NOR gate 45. The NOR gate 45 generates a signal of high level, as shown in Fig. 7E. The bases of the transistors Q1 and Q2 receive the signals of high level, as shown in Fig. 7F. The transistors Q1 and Q2 are turned on, and the voltages of +12 V and +5 V are supplied to the amp 11, as shown in Figs. 7G and 7H, respectively. Thereafter, the controller 3 performs the seek operation in response to the seek instruction from the processor 1, and the STEP signal (Fig. 7B) and the DRIVE SELECT signal are supplied to the AND gate 37. The output from the AND gate 37 is latched by the flip-flop 41, as shown in Fig. 7C. The Q output of high level from the flip-flop 41 and the Q output of low level from tranflip-flop 43 are simultaneously supplied to the NOR gate 45. In this case, since the signal of low level is supplied from the NOR gate 45 to the bases of the transistors Q1 and Q2, the transistors Q1 and Q2 are kept off, and the transistors Q3 and Q4 are also kept off. Therefore, the voltages of +12 V and +5 V are not supplied to the amp 11 in the same manner as described above. As shown in Fig. 7B, when a predetermined period of time T2 has elapsed after the final step pulse is supplied, the Q output from the flip-flop 41 falls. For this reason, the Q outputs from the flip-flops 41 and 43 go low. The signals of low level are supplied to the NOR gate 45, so that the transistors Q1 and Q2 and then the transistors Q3 and Q4 are turned on. As a result, the voltages of +12 V and +5 V shown in Figs. 7G and 7H are supplied to the amp 11. A period of time T2 until the Q output from the flip-flop 41 falls in response to the final step pulse after an input T to the flip-flop 41 is hit by a trigger signal from the AND gate 37 and an output signal then rises is designed to be longer than the step pulse width T3 of Fig. 7B. With such a design, the power supply voltage 27 can be continuously cut off from the amp 11 during the seek operation. The above embodiment exemplifies the floppy disk driver. However, the present invention is not limited to this. For example, the present invention can be applied to a hard disk driver or an optical disk driver.

Claims: A floppy disk apparatus comprising a magnetic head (9) for accessing a magnetic recording medium, generating a read signal in a data read mode and generating a write signal in a data write mode, a read/write amplifier (11) for amplifying the read signal supplied from said magnetic head (9) and the write signal supplied to said magnetic head (9), characterized in that there is provided power control means (33, 35; 41, 43, 45, Q1, Q2, Q3, Q4) for supplying power to said read/write amplifier while said read/write amplifier (11) is operative and prohibiting power being supplied to said read/write amplifier (11) while said read/write amplifier (11) is inoperative. An apparatus according to claim 1, characterized in that said power controll means (33, 35) comprises: first and second monostable multivibrators (41, 43) whose input is hit in response to a STEP signal for driving said stepping motor (13) and a MOTORON signal for driving said spindle motor (17) as trigger signals; a gate (45) for generating significant data when said first and second monostable multivibrators (41, 43) generate nonsignificant data; and switch means (Q1, Q2, Q3, Q4), connected to said read/write amplifier (11), for prohibiting power being supplied to said read/write amplifier (11). An apparatus according to claim 2, characterized in that outputs from said first and second monostable multivibrators (41, 43) are gate-controlled to turn off said switch means (Q1, Q2, Q3, Q4) when one of outputs from said first and second monostable multivibrators (41, 43) is significant data. An apparatus according to claim 2, characterized in that said second monostable multivibrator (43) disables an output signal therefrom before a first STEP signal is supplied to said first monostable multi-vibrator (41) after said second monostable multivibrator (43) receives the MOTORON signal to enable the output signal therefrom, and a period for disabling the output signal from said first monostable multivibrator (41) upon reception of a final STEP signal is set to be longer than a pulse width of the STEP signal, so that power being supplied to said read/write amplifier (11) is prohibited for a predetermined period of time after starting of said spindle motor (17) and for a predetermined period of time after the seek operation.

Inventors: OSAFUNE, KOJI C/O PATENT DIVISION, SANO, MASAKI C/O PATENT DIVISION
Applicants: KABUSHIKI KAISHA TOSHIBA
Application year: 1985
Main classification: G11B19
IPC codes: G11B19, G11B5