Patent Publication Number: US-2006018222-A1

Title: Information storage apparatus

Description:
BACKGROUND OF THE INVENTION  
      i) Field of the Invention  
      The present invention relates to an information storage apparatus for holding an information recording medium in a predetermined position and rotating the medium in a predetermined direction to perform at least an information reproduction with respect to the information recording medium.  
      ii) Description of Related Art  
      Information storage apparatuses such as a hard disk drive and a magnetooptic (MO) disk drive have heretofore been known, and in the information storage apparatus, a disk or card information recording medium is rotated by a spindle motor or the like at a high speed to access the information recording medium. The information storage apparatus is incorporated into a computer system as the information storage apparatus for a computer in many cases.  
      In recent years, information communication networks such as Internet have rapidly been developed, and with the development, portable computer systems such as a notebook-size personal computer have also been developed. When the aforementioned information storage apparatus is incorporated and utilized in the portable computer system, it is necessary to operate the information storage apparatus by a storage battery or a dry battery. Moreover, in order to lengthen life of the battery, and construct the portable computer system which can be utilized for a long time, development of the information storage apparatus with a little current consumption has strongly been demanded.  
      Additionally, when the information storage apparatus continues to be driven by the battery, an electric power stored in the battery is soon consumed, and it becomes impossible to continue driving the information storage apparatus. Therefore, the information storage apparatus or the computer system is provided with a function of issuing an alarm to a user when a remaining power of the battery runs short. For example, the information storage apparatus or the computer system monitors a voltage of the battery, and issues an alarm to let the user know that the remaining power runs short when the voltage indicates a predetermined level or less. A state in which the remaining power of the battery reaches a level requiring the alarm will hereinafter be referred to as a battery alarm state.  
      The user, notified of the battery alarm state, stops using the information storage apparatus and recovers the information recording medium from the apparatus in many cases. In order to recover the information recording medium from the information storage apparatus, it is necessary to stop rotating the information recording medium and take the medium out of the apparatus, but the stopping and taking of the medium are generally performed by the motor or the like. An operation of the information storage apparatus for stopping the rotation of the information recording medium and taking the medium out of the apparatus will hereinafter be referred to as an eject operation.  
      In a conventional information storage apparatus, a large power is consumed during stopping of the rotation of the information recording medium, a cartridge is incompletely ejected, in the course of the eject operation the power of the battery or the like runs out and the information storage apparatus stops in some cases. When the information storage apparatus stops in the course of the eject operation, there is a possibility that the recovering of the information recording medium becomes impossible and a possibility that breakage of the information recording medium is caused.  
     SUMMARY OF THE INVENTION  
      The present invention has been developed in consideration of the aforementioned circumstances, and an object thereof is to provide an information storage apparatus in which even when a remaining power of a battery is little, an information recording medium can safely be taken out.  
      To achieve the aforementioned object, according to the present invention there is provided a first information storage apparatus, operated by an electric power, for holding an information recording medium in a predetermined position and rotating the information recording medium in a predetermined direction to perform at least an information reproduction with respect to the information recording medium, said information storage apparatus comprising: 
          a recognition section for recognizing whether or not said electric power is a power of a predetermined level or more; and     a decelerator for decelerating rotation of said information recording medium in a first deceleration mode which consumes a relatively large power, or decelerating the rotation of said information recording medium in a second deceleration mode which consumes a relatively small power, depending upon whether said recognition section recognizes that said electric power is the power of the predetermined level or more, or that said electric power is less than the predetermined level.        

      Here, the second deceleration mode may be provided with a smaller peak of power consumption than that of the first deceleration mode, a smaller average value of the power consumption than that of the first deceleration mode, or a smaller total amount of the power consumption than that of the first deceleration mode.  
      According to the first information storage apparatus of the present invention, when there is no allowance in the electric power, the second deceleration mode is selected and the electric power is saved. Therefore, in the first information storage apparatus, even when a remaining power of a battery is little, a probability that the apparatus stops in the course of an eject operation is low, and the information recording medium can safely be taken out.  
      Preferably the first information storage apparatus of the present invention, “further comprises a driver for driving the information recording medium in the predetermined direction, and 
          the decelerator employs a deceleration mode for stopping the driving by the driver to decelerate the rotation of the information recording medium as the second deceleration mode.”       

      Moreover, also preferably the first information storage apparatus of the present invention “further comprises a driver for driving the information recording medium in the predetermined direction; and 
          a brake for applying a brake force to the information recording medium to decelerate the rotation, and     the decelerator employs a deceleration mode for stopping the driving by the driver to decelerate the rotation of the information recording medium and subsequently operating the brake to further decelerate the rotation of the information recording medium as the second deceleration mode.”       

      If the driving by the driver stops, unforced deceleration occurs by viscosity resistance of a grease or the like, air resistance, friction resistance of a bearing, and the like, and this deceleration requires no electric power for the deceleration. Therefore, the battery power can considerably be saved, and the taking-out of the information recording medium is performed more safely. Moreover, when forced deceleration is performed after the unforced deceleration, saving of the electric power and shortening of a processing time can both be realized and the apparatus is therefore useful for a user.  
      To achieve the aforementioned object, according to the present invention there is provided a second information storage apparatus for holding an information recording medium in a predetermined position and rotating the information recording medium in a predetermined direction to perform at least an information reproduction with respect to the information recording medium, the information storage apparatus comprising: 
          a brake for applying a brake force to the information recording medium to decelerate rotation; and     an intermittent braking decelerator for intermittently operating the brake to decelerate the rotation of the information recording medium.        

      The battery has a property of suppressing the power consumption peak even with little remaining power and inhibiting a voltage drop to increase the total amount of power supply.  
      According to the second information storage apparatus of the present invention, by intermittently operating the brake, the power consumption peak is suppressed, and the information recording medium can safely be taken out even with little remaining power of the battery.  
      Moreover, to achieve the aforementioned object, according to the present invention there is provided a third information storage apparatus for holding an information recording medium in a predetermined position and rotating the information recording medium in a predetermined direction to perform at least an information reproduction with respect to the information recording medium, the information storage apparatus comprising: 
          a driver for receiving a signal indicating a rotation speed, and driving the information recording medium in the predetermined direction in such a manner that the information recording medium rotates at the rotation speed indicated by the signal; and     a signal controlling decelerator for inputting a signal indicating a rotation speed lower than the rotation speed of the information recording medium to the driver to decelerate rotation of the information recording medium.        

      According to the third information storage apparatus of the present invention, the driver having received the signal indicative of the rotation speed lower than the rotation speed of the information recording medium inhibits the driving of the information recording medium to lower the rotation speed. This considerably saves the power consumption, and it is possible to safely take out the information recording medium even with little remaining power of the battery.  
      Additionally, with respect to the second and third information storage apparatuses of the present invention, only basic mode is described herein, but this simply avoids redundancy, and the second and third information storage apparatuses of the present invention includes not only the basic mode of the information storage apparatus but also various modes of information storage apparatuses corresponding to respective modes of the first information storage apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an appearance view showing a magnetooptic (MO) disk drive according to one embodiment of an information storage apparatus of the present invention.  
       FIG. 2  is an internal constitution diagram of the MO disk drive.  
       FIG. 3  is a constitution diagram of a spindle motor driver.  
       FIG. 4  is a graph showing an FG signal.  
       FIG. 5  is a flowchart showing an operation of the MO disk drive before/after a battery alarm state.  
       FIG. 6  is a flowchart showing a stop operation for stopping an MO disk according to one example of a first deceleration mode referred to in the present invention.  
       FIG. 7  is a time chart of a drive control signal in the stop operation for stopping the MO disk according to one example of the first deceleration mode referred to in the present invention.  
       FIG. 8  is a flowchart showing the stop operation for stopping the MO disk according to a first example of a second deceleration mode referred to in the present invention.  
       FIG. 9  is a time chart of the drive control signal in the stop operation for stopping the MO disk according to the first example of the second deceleration mode referred to in the present invention.  
       FIG. 10  is a time chart of the drive control signal in the stop operation for using a spindle brake signal constituted of a period pulse train to stop the MO disk.  
       FIG. 11  is a graph showing a measurement result of current consumption in the stop operation shown in  FIGS. 6 and 7 .  
       FIG. 12  is a graph showing the measurement result of the current consumption in the stop operation shown in  FIGS. 8 and 9 .  
       FIG. 13  is a flowchart showing the stop operation for stopping the MO disk according to a second example of the second deceleration mode referred to in the present invention.  
       FIG. 14  is a time chart of the drive control signal and spindle clock signal in the stop operation for stopping the MO disk according to the second example of the second deceleration mode referred to in the present invention.  
       FIG. 15  is a graph showing again the measurement result of the current consumption in the stop operation shown in  FIGS. 6 and 7 .  
       FIG. 16  is a graph showing the measurement result of the current consumption in the stop operation shown in  FIGS. 13 and 14 .  
       FIG. 17  is a graph showing a time until a spindle motor and MO disk stop by friction resistance or the like.  
       FIG. 18  is a flowchart showing the stop operation for stopping the MO disk according to a third example of the second deceleration mode referred to in the present invention.  
       FIG. 19  is a time chart of the drive control signal and FG signal in the stop operation for stopping the MO disk according to the third example of the second deceleration mode referred to in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      An embodiment of the present invention will be described hereinafter.  
       FIG. 1  is an appearance view showing a magnetooptic (MO) disk drive as one embodiment of an information storage apparatus of the present invention.  
      An MO disk drive  1  shown herein is attached to a socket (not shown) which also serves as a cover, and connected to a personal computer or another host apparatus via the socket. Moreover, the MO disk drive  1  receives power supply from the host apparatus. A cartridge  2  is inserted into the MO disk drive  1  via an insertion port  1 A.  
      The cartridge  2  incorporates a magnetooptic (MO) disk  2 A as one example of an information recording medium referred to in the present invention, and the MO disk drive  1  rotates the MO disk  2 A in a predetermined forward rotation direction to perform information recording and information reproduction with respect to the MO disk  2 A. Moreover, in the MO disk drive  1  of the present embodiment, when an eject button  1 B is pressed, an eject operation is executed, and a motor built in the MO disk drive  1  ejects the MO disk  2 A together with the cartridge  2  out of the apparatus.  
       FIG. 2  is an internal constitution diagram of the MO disk drive.  
      The MO disk drive  1  is, as shown in  FIG. 1 , largely divided into an enclosure  11 , provided with the cartridge  2  shown in  FIG. 1  inserted therein, for accessing the MO disk  2 A in the cartridge  2 , and a control unit  10  for controlling an operation of the enclosure  11 .  
      The MO disk  2 A of the cartridge  2  inserted in the enclosure  11  is held by a spindle motor  40 . This spindle motor  40  is supplied with a drive current by a spindle motor driver  38  following a drive control signal emitted from a micro processor unit (MPU)  12 , and performs rotation drive of the MO disk  2 A in the forward rotation direction and forced stop of the MO disk  2 A. Here, the MPU  12  carries a role as one example of a decelerator referred to in the present invention. Moreover, the spindle motor driver  38  and spindle motor  40  constitute one example of a driver referred to in the present invention, and the spindle motor driver  38  and spindle motor  40  also serve as one example of a brake referred to in the present invention.  
      As described above, the MO disk drive  1  receives the power supply from the host apparatus to operate, and the MPU  12  also serving as one example of a recognition section referred to in the present invention monitors a power level. Specifically, a voltage of a power supply line  13  for guiding the electric power supplied from the host apparatus to respective sections of the MO disk drive  1  is A/D converted by an A/D conversion circuit built in a digital signal processor (DSP)  16  and taken into the MPU  12 , and the MPU  12  compares a voltage level with a predetermined standard level.  
      When the eject button  1 B shown in  FIG. 1  is pressed, the MPU  12  emits and inputs an eject signal to an eject motor driver  51 , the eject motor driver  51  supplies the drive current to an eject motor  52 , and the eject motor  52  ejects the MO disk  2 A together with the cartridge  2  out of the MO disk drive  1 .  
      Moreover, the enclosure  11  is provided with a laser diode unit  30 , and during information reproduction, a laser diode  30 _ 1  of the laser diode unit  30  emits a laser light with a predetermined strength. The laser light strength is controlled by a monitor photo diode  30 _ 2  and laser diode control circuit  22 . Furthermore, the MO disk  2 A is irradiated with the laser light by a focus optical system (not shown), and a reflected light is generated in accordance with information recorded in the MO disk  2 A. The reflected light is received by an ID/MO detector  32  and an ID signal and MO signal are detected. The ID and MO signals are amplified by a head amplifier  34 , inputted to a read LSI circuit  24 , demodulated by a read demodulation circuit  25  synchronized with a period signal generated by changing a period of a basic period signal of a crystal vibrator  101  by a frequency synthesizer  26 , and converted to reproduction data. The reproduction data is checked for an error by an error correction code (ECC) processor  14 _ 2  of an optical disk controller  14 , and sent to the host apparatus via a buffer memory  18  and interface  17 .  
      On the other hand, during information recording, the host apparatus sends recording data to the optical disk controller  14  via the buffer memory  18  and interface  17 . After an error correction code is added by the error correction code (ECC) processor  14 _ 2 , the recording data is inputted to a write LSI circuit  20 . Moreover, during formatting of the MO disk  2 A, a formatter  14 _ 1  of the optical disk controller  14  generates format data and inputs the data to the write LSI circuit  20 . The recording data and format data are modulated by a write modulation circuit  21  of the write LSI circuit  20  and converted to a write signal, the write signal is inputted to the laser diode unit  30 , and the laser diode  30 _ 1  emits the laser light in response to the write signal.  
      Moreover, during information recording and formatting, the MPU  12  emits a magnetic field generation signal and inputs the signal to the digital signal processor (DSP)  16 . The DSP  16  controls a magnetic head driver  42  in response to the magnetic field generation signal and an output signal of a temperature sensor  36 , the magnetic head driver  42  supplies a current to a magnetic head electromagnet  44 , and a recording magnetic field is generated on the MO disk  2 A. By the recording magnetic field and the laser light in response to the write signal, the information is recorded in the MO disk  2 A, or the MO disk  2 A is formatted.  
      Furthermore, the MO disk drive  1  is provided with a voice coil motor  68 , supplied with the drive current by a voice coil motor (VCM) driver  66 , for moving an optical head with the focus optical system and laser diode unit  30  mounted thereon along the surface of the MO disk  2 A. The voice coil motor (VCM) driver  66  is controlled by the DSP  16  in response to tracking error signal (TES) and tracking zero cross (TZC) detected from a detect signal obtained by a TES detector  47  by a TES detection circuit  48  and TZC detection circuit  50 , and a seek signal emitted from the MPU  12 .  
      Additionally, the MO disk drive  1  is also provided with a focus actuator  60 , supplied with the drive current by a focus actuator driver  58 , for driving the focus optical system. The focus actuator driver  58  is controlled by the DSP  16  in response to focus error signal (FES) detected from the detect signal obtained by a FES photodetector  45  by an FES detection circuit  46 .  
      The spindle motor driver  38  and spindle motor  40  which serve both as one example of the driver referred to in the present invention and one example of the brake referred to in the present invention will next be described in detail.  
       FIG. 3  is a constitution diagram of the spindle motor driver.  
      The spindle motor  40  is a motor which rotates when the drive current is successively supplied to three phases of U, V and W phases, and the spindle motor driver  38  is provided with a power source  38 _ 1  for supplying the drive current to the U, V, and W phases. This power source  38 _ 1  is also supplied with the electric power from the host apparatus via the power supply line.  
      Moreover, the spindle motor driver  38  is also provided with a commutation  38 _ 2  for changing a supply phase to be supplied with the current among the U, V, and W phases in a circulating manner, and a start oscillator (OSC)  38 _ 3  for generating a start period signal as a standard of a timing for changing the supply phase by the commutation  38 _ 2 . When the supply phase is changed by the spindle motor driver  38  in order of the forward rotation direction, the spindle motor  40  rotates/drives the MO disk  2 A (see  FIG. 1 ) in the forward rotation direction. Conversely, when the supply phase is changed in order of a backward rotation direction reverse to the forward rotation direction, the spindle motor  40  generates a drive force in the backward rotation direction, that is, a brake force to forcibly decelerate the MO disk  2 A. Additionally, a reverse rotation preventing function is disposed, and the MO disk  2 A is prevented from rotating in the backward rotation direction. Therefore, when the rotation continues to be decelerated by the brake force in the backward rotation direction to reach speed “0”, the spindle motor  40  and MO disk  2 A stop as they are.  
      Furthermore, the spindle motor driver  38  is also provided with a start control circuit  38 _ 4  which receives the drive control signal from the MPU  12  (see  FIG. 2 ) to control the commutation  38 _ 2  and power source  38 _ 1 . To the start control circuit  38 _ 4 , a binary spindle on signal SPDLON and binary spindle brake signal BRAKE are inputted as the drive control signals. Subsequently, the start control circuit  38 _ 4  operates/stops the power source  38 _ 1  in accordance with an on/off state of the spindle on signal SPDLON, and instructs the commutation  38 _ 2  to change the supply phase in the backward rotation direction or the forward rotation direction in accordance with the on/off state of the spindle brake signal BRAKE. When the power source  38 _ 1  stops, the current supply to the spindle motor  40  by the power source  38 _ 1  stops, and the drive force of the spindle motor  40  turns to “0” both in the forward rotation direction and backward rotation direction.  
      Moreover, the spindle motor  40  inputs back electromotive voltages of the U, V, and W phases, and a center tap voltage indicating a back electromotive voltage standard (0 V) to the spindle motor driver  38 , and the back electromotive voltages and center tap voltage are inputted to a back electromotive voltage detection circuit  38 _ 5 . The back electromotive voltage detection circuit  38 _ 5  outputs a period signal (FG signal) synchronous with the rotation of the spindle motor  40  based on the back electromotive voltages and center tap voltage.  
       FIG. 4  is a graph showing the FG signal.  
      The abscissa of the graph indicates time, an upper part of the graph shows the back electromotive voltages of the U, V, and W phases while the center tap voltage is “0 V”, and these back electromotive voltages form a sine waveform. Moreover, a lower part of the graph shows the FG signal, and the FG signal is a binary signal whose value is reversed every time the back electromotive voltages of the U, V, and W phases reach a zero cross.  
      Turning back to  FIG. 3  the description will continue.  
      The FG signal outputted from the back electromotive voltage detection circuit  38 _ 5  is inputted to the MPU, commutation  38 _ 2 , and frequency division circuit  38 _ 6 . The frequency division circuit  38 _ 6  subjects the FG signal to frequency division and inputs the signal to a speed distinction circuit  38 _ 7 . Moreover, the MPU inputs a spindle clock signal CLK to another frequency division circuit  38 _ 8 , and the circuit subjects the spindle clock signal CLK to the frequency division and inputs the signal to the speed distinction circuit  38 _ 7 . A period of the spindle clock signal CLK represents a target value of the rotation speed of the spindle motor  40  and MO disk  2 A. The speed distinction circuit  38 _ 7  compares the signals inputted from two frequency division circuits  38 _ 6 ,  38 _ 8  with each other to distinguish the rotation speed of the spindle motor  40 . Subsequently, the circuit outputs, to the MPU, a Ready signal indicating ‘L’ when the rotation speed is within a predetermined steady rotation speed range centering on the target value of the rotation speed indicated by the spindle clock signal CLK, and indicating ‘H’ when the rotation speed is outside the range.  
      Additionally, the commutation  38 _ 2  is also provided with a function of adjusting a supply phase change speed to allow the rotation speed of the spindle motor  40  to approach the target value of the rotation speed indicated by the spindle clock signal CLK.  
      An operation of the MO disk drive  1  shown in  FIGS. 1 and 2  will next be described with reference to a flowchart.  
       FIG. 5  is a flowchart showing the operation of the MO disk drive  1  before/after the battery alarm state.  
      The MO disk drive repeatedly executes a read/write operation to perform information recording and information reproduction with respect to the MO disk (step S 101 ) as long as there is an allowance in a remaining power of the battery or the like (step S 102 : No). In a case in which the eject operation starts while the read/write operation is repeated in this manner, the MO disk decelerates and stops according to one example of a first deceleration mode referred to in the present invention.  
       FIG. 6  is a flowchart showing a stop operation for stopping the MO disk according to one example of the first deceleration mode referred to in the present invention, and  FIG. 7  is a time chart of the drive control signal in the stop operation.  
      At the start of this stop operation (left end of  FIG. 7 ), the spindle on signal (upper part of  FIG. 7 ) is in an on state, the spindle brake signal (lower part of  FIG. 7 ) is in an off state, and the MO disk is driven in the forward rotation direction. Subsequently, when the operation for stopping the MO disk starts, the spindle brake signal is changed to the on state (step S 201  of  FIG. 6 , time T 201  of  FIG. 7 ), and the brake force acts on the MO disk in the backward rotation direction to perform forced deceleration. During deceleration of the MO disk, the on/off state of the FG signal is monitored, and it is judged based on the monitor result whether or not the MO disk stops (step S 202  of  FIG. 6 ). The on/off state of the FG signal changes in synchronization with the rotation of the MO disk. Therefore, when an on/off state change frequency of the FG signal becomes sufficiently low, it is judged that the MO disk has stopped. Subsequently, both the spindle on signal and the spindle brake signal are changed to the off state (step S 203  of  FIG. 6 , time T 203  of  FIG. 7 ).  
      When the forced and continuous deceleration is performed, a large power is consumed. However, when there is an allowance in the remaining power of the battery, a processing time is preferentially reduced, and the forced and continuous deceleration is performed.  
      Turning back to  FIG. 5  the description will continue.  
      When the remaining power decreases by repetition of the read/write operation, and the battery alarm state occurs (step S 102 : Yes), a user is notified of the battery alarm state (step S 103 ). Thereafter, the user instructs the information recording and information reproduction to be stopped, and a standby state is retained until the user presses the eject button to instruct the start of the eject operation (step S 104 ).  
      When the eject operation starts, a servo of the focus optical system stops, and the laser diode is turned off (step S 105 ). Subsequently, a second deceleration mode described later and referred to in the present invention decelerates and stops the MO disk (step S 106 ), the eject motor rotates, and the MO disk is ejected out of the apparatus (step S 107 ).  
      A first example of the second deceleration mode referred to in the present invention will be described hereinafter.  
       FIG. 8  is a flowchart showing the stop operation for stopping the MO disk according to the first example of the second deceleration mode referred to in the present invention, and  FIG. 9  is a time chart of the drive control signal in the stop operation.  
      In this stop operation according to the first example of the second deceleration mode, the MPU generates the spindle brake signal in a pulse train form in order to intermittently execute the forced deceleration. Specifically, here the MPU corresponds to one example of an intermittent braking decelerator referred to in the present invention. Moreover, in the first example, a continuation time of the on state and continuation time of the off state in the spindle brake signal of the pulse train form change with elapse of time, respectively.  
      When this stop operation starts, a longest time T 1  of the continuation time of the on state, initial value of a continuation time T 2  of the on state, and initial value of a continuation time T 3  of the off state in the spindle brake signal are set (step S 301  of  FIG. 8 ).  
      Subsequently, the spindle brake signal is changed to the on state (step S 302  of  FIG. 8 , time T 302 _ 1  of  FIG. 9 ), standby holds for the continuation time T 2  of the on state (step S 303  of  FIG. 8 ), the spindle brake signal is changed to the off state (step S 304  of  FIG. 8 , time T 304 _ 1  of  FIG. 9 ), and standby holds for the continuation time T 3  of the off state (step S 305  of  FIG. 8 ). This generates a pulse form of spindle brake signal, and the brake force in the backward rotation direction acts for the continuation time T 2  of the on state.  
      Thereafter, when the continuation time T 2  of the on state fails to exceed the longest time T 1  (step S 306  of  FIG. 8 : No), the continuation time T 2  of the on state is lengthened, the continuation time T 3  of the off state is shortened (step S 307  of  FIG. 8 ), and a proportion of the forced deceleration gradually increases. Subsequently, while the rotation speed of the spindle motor and MO disk exceeds a predetermined value (step S 308  of  FIG. 8 : No), the steps S 302  to S 307  are repeated. As a result, the on/off state change of the spindle brake signal is repeated (time T 302 _ 2 , time T 304 _ 2 , . . . of  FIG. 9 ), the spindle brake signal of the pulse train form is generated, and the forced deceleration by the brake force in the backward rotation direction is repeatedly and intermittently performed.  
      With the high rotation speed of the spindle motor and MO disk, when the brake force in the backward rotation direction is continuously generated, the rotation speed is largely attenuated in a short time, but a power consumption peak is high, and a total amount of electric power obtained from the battery is small. On the other hand, when the brake force in the backward rotation direction is intermittently generated, time required for deceleration is long, but the power consumption peak is small, and the total amount of the power obtained from the battery is large. Additionally, with the low rotation speed, even when a method of generating the drive force differs, there is no large difference in the power consumption peak.  
      When the rotation speed of the spindle motor and MO disk reaches the predetermined value or less by the intermittent deceleration (step S 308  of  FIG. 8 : Yes), to securely stop the MO disk, and the like, the spindle brake signal is changed to the on state (step S 309  of  FIG. 8 , time T 309  of  FIG. 9 ), and the brake force continuously acts on the MO disk in the backward rotation direction. Similarly as described above, during the deceleration of the MO disk, the on/off state of the FG signal is monitored, and it is judged based on the monitor result whether or not the MO disk has stopped (step S 310  of  FIG. 9 ). When it is judged that the MO disk has stopped, both the spindle on signal and the spindle brake signal are changed to the off state (step S 311  of  FIG. 8 , time T 311  of  FIG. 9 ). This ends the stop operation.  
      Additionally, the steps S 306  and S 307  can be omitted, and when these steps are omitted, the on/off state of the spindle brake signal is changed at a fixed period, and the spindle brake signal constituted of a period pulse train is generated.  
       FIG. 10  is a time chart of the drive control signal in the stop operation for using the spindle brake signal constituted of the period pulse train to stop the MO disk.  
      In this stop operation, the on/off state of the spindle brake signal is periodically changed (time T 302 , time T 304 ) and forced deceleration is periodically executed. Since the subsequent operation is similar to the operation described with reference to  FIGS. 8 and 9 , the description thereof is omitted.  
      Here, a measurement result of a current consumption in the stop operation will be described.  
       FIG. 11  is a graph showing the measurement result of the current consumption in the stop operation shown in  FIGS. 6 and 7 , and  FIG. 12  is a graph showing the measurement result of the current consumption in the stop operation shown in  FIGS. 8 and 9 .  
      In these graphs, a first step on top shows a spindle on signal waveform L 11 , L 21 , a second step shows a spindle brake signal waveform L 12 , L 22 , a third step shows an FG signal waveform L 13 , L 23 , and a fourth step shows a current consumption waveform L 14 , L 24 .  
      In the graph of  FIG. 11 , the spindle brake signal waveform L 12  is continuously in the on state from deceleration start time T 201 , and a steep rising P 1  of a peak current occurs in the current consumption waveform L 14 . On the other hand, in the graph of  FIG. 12 , the spindle brake signal waveform L 22  indicates a waveform of the pulse train form for a while from the deceleration start time T 301 . Moreover, the current consumption waveform L 24  causes a moderate rising P 2  and indicates the waveform of the pulse train form. As a result, the power consumption peak is suppressed and the average value of the power consumption is also suppressed to suppress consumption of the battery or the like. Therefore, the electric power for driving the eject motor is secured, and the MO disk is safely taken out.  
      Additionally, as the deceleration mode in the step S 106  of  FIG. 6 , a second example of the second deceleration mode referred to in the present invention will be described hereinafter.  
      In the second example, the MPU changes the frequency of the spindle clock signal and decelerates the rotation of the spindle motor and MO disk. Specifically, when the second example is employed, the MPU corresponds to one example of a signal controlling decelerator referred to in the present invention.  
       FIG. 13  is a flowchart showing the stop operation for stopping the MO disk according to the second example of the second deceleration mode referred to in the present invention, and  FIG. 14  is a time chart of the drive control signal and spindle clock signal in the stop operation.  
      At the start of the stop operation, it is assumed that the rotation speed of the spindle motor and MO disk agrees with the rotation speed indicated by the spindle clock signal.  
      When the stop operation starts, the frequency of the spindle clock signal is lowered (step S 401  of  FIG. 13 , time T 401 _ 1  of  FIG. 14 ), and the spindle clock signal indicates the rotation speed lower than the rotation speed of the MO disk. As a result, the spindle motor driver lowers the drive force in the forward rotation direction, and the rotation speed of the MO disk or the like is attenuated to reach the rotation speed indicated by the spindle clock signal.  
      When the frequency of the spindle clock signal lowers in the step S 401 , the standby state holds until the rotation speed of the MO disk or the like is stabilized to reach the rotation speed indicated by the spindle clock signal (step S 402  of  FIG. 13 ).  
      In the standby state the Ready signal is monitored. As described above, the Ready signal indicates ‘L’ when the rotation speed of the MO disk or the like is within the predetermined steady rotation speed range centering on the rotation speed indicated by the spindle clock signal, and indicates ‘H’ when the rotation speed is outside the range. Therefore, immediately after the spindle clock signal frequency lowers, the MO disk rotation speed exceeds the rotation speed indicated by the spindle clock signal, and the Ready signal indicates ‘H’. Thereafter, when the MO disk rotation speed is attenuated to reach the steady rotation speed range, the Ready signal indicates ‘L’, and it is judged that the MO disk rotation speed is stabilized (step S 402  of  FIG. 13 : Yes).  
      While the rotation speed of the MO disk or the like exceeds a predetermined rotation speed suitable for the forced deceleration by the brake force in the backward rotation direction (step S 403  of  FIG. 13 : No), the steps S 401  and S 402  are repeated, and the spindle clock signal frequency lowers in a stepwise manner (time T 401 _ 2 , . . . of  FIG. 14 ).  
      Thereafter, when the rotation speed of the MO disk or the like reaches the predetermined rotation speed or less (step S 403  of  FIG. 13 : Yes), similarly as the first example of the second deceleration mode, in order to securely stop the MO disk, the spindle brake signal is changed to the on state (step S 404  of  FIG. 13 , time T 404  of  FIG. 14 ), and the brake force is continuously applied to the MO disk in the backward rotation direction. Moreover, similarly as described above, it is judged based on the on/off state of the FG signal whether or not the MO disk has stopped (step S 405  of  FIG. 13 ). When it is judged that the disk has stopped, both the spindle on signal and the spindle brake signal are changed to the off state (step S 406  of  FIG. 13 , time T 406  of  FIG. 14 ). This ends the stop operation.  
      Here, the measurement result of the current consumption in the stop operation will also be described.  
       FIG. 15  is a graph showing again the measurement result of the current consumption in the stop operation shown in  FIGS. 6 and 7 , and  FIG. 16  is a graph showing the measurement result of the current consumption in the stop operation shown in  FIGS. 13 and 14 .  
      In these graphs, a first step on top shows current consumption waveform L 31 , L 41 , a second step shows spindle on signal waveform L 32 , L 42 , a third step shows spindle brake signal waveform L 33 , L 43 , and a fourth step shows FG signal waveform L 34 , L 44 . Additionally, the abscissa of the graph of  FIG. 16  is reduced in size to ⅕ with respect to the abscissa of the graph of  FIG. 15 , and the first step on top of the graph of  FIG. 16  also indicates a waveform L 31 ′ corresponding to the current waveform L 31  of the graph of  FIG. 15  for comparison.  
      Similarly as the graph of  FIG. 11 , in the graph of  FIG. 15 , the spindle brake signal waveform L 33  is continuously in the on state from the deceleration start time T 201 , and in the current consumption waveform L 31  the steep rising P 1  of the peak current occurs.  
      On the other hand, in the graph of  FIG. 16 , at a deceleration start time T 401  a falling occurs in the current consumption waveform L 41 . Here, during the deceleration start a revolution number is 3600 rpm, and by lowering the spindle clock signal frequency the revolution number is lowered by 200 rpm each. When the revolution number reaches 1000 rpm or less, the spindle brake signal waveform L 43  is in the on state, in the current consumption waveform L 41  a rising P 3  occurs, but a height of the rising P 3  is lower than a height P 1 ′ of the steep rising P 1 .  
      Furthermore, with respect to a peak width of a current peak on and after the rising P 1  of the waveform L 31 ′, the peak width of the current peak on and after the rising P 2  of the waveform L 41  is short, and the total amount of the power consumption indicated by the waveform L 41  is obviously smaller than the total amount of the power consumption indicated by the waveform L 31 ′.  
      In this manner, in the second example of the second deceleration mode referred to in the present invention, drastic saving of the power consumption can be realized, the electric power for driving the eject motor is secured and the MO disk can safely be ejected.  
      As the deceleration mode in the step S 106  of  FIG. 6 , a third example of the second deceleration mode referred to in the present invention will be described hereinafter.  
      In the third example, the rotation of the MO disk and spindle motor is decelerated by viscosity resistance of a grease or the like, air resistance, friction resistance of a bearing, and the like in an unforced manner. Specifically, the driving of the MO disk by the spindle motor stops, the drive force turns to “0” both in the forward rotation direction and the backward rotation direction, and the MO disk and spindle motor rotate by inertia and decelerate under the friction resistance or the like.  
       FIG. 17  is a graph showing a time until the spindle motor and MO disk stop by the friction resistance or the like.  
      The ordinate of the graph indicates the time required until the stop, and the abscissa indicates the revolution number in the beginning. Moreover, a line L 51  with white circles attached thereto indicates the time required for the stop under environment of 50° C., and a line L 52  with black circles attached thereto indicates the time required for the stop under environment of 25° C. In either environment, since the stop time of about 20 seconds is necessary. Therefore, it can be seen that for example, when rotation is performed by inertia for about 15 seconds, the deceleration is performed by the friction resistance to achieve a sufficiently low speed.  
      In the third example of the second deceleration mode referred to in the present invention, the deceleration is utilized.  
       FIG. 18  is a flowchart showing the stop operation for stopping the MO disk according to the third example of the second deceleration mode referred to in the present invention, and  FIG. 19  is a time chart of the drive control signal and FG signal in the stop operation.  
      When the stop operation starts, the spindle on signal is changed to the off state, and rotation drive of the MO disk by the spindle motor stops (step S 501  of  FIG. 18 , time T 501  of  FIG. 19 ). Thereafter, the standby state holds, for example, for 15 seconds, that is, for a predetermined time for which the MO disk is expected to sufficiently decelerate by the friction resistance or the like (step S 502  of  FIG. 18 ). In the standby state, the power consumption by the spindle motor is “0”. Moreover, when the spindle on signal is in the off state, no FG signal is outputted, and it is impossible to confirm the rotation speed in the standby state. When the predetermined time elapses and the standby state ends, in order to securely stop the MO disk, both the spindle on signal and the spindle brake signal are changed to the on state (step S 503  of  FIG. 18 , time T 503  of  FIG. 19 ), and the MO disk is forced to decelerate by the brake force in the backward rotation direction. Moreover, similarly as described above, it is judged based on the on/off state of the FG signal whether or not the MO disk has stopped (step S 504  of  FIG. 18 ). When it is judged that the disk has stopped, both the spindle on signal and the spindle brake signal are changed to the off state (step S 505  of  FIG. 18 , time T 505  of  FIG. 19 ). This ends the stop operation.  
      Additionally, in the aforementioned standby state (step S 502  of  FIG. 18 ), the MO disk can stand by for a sufficient standby time to completely stop by the friction resistance. Moreover, in the standby case, when the standby time has expired, the stop operation ends, and the MO disk is ejected.  
      In the third example of the second deceleration mode referred to in the present invention, the drastic deceleration of the rotation of the MO disk is realized at the power consumption of “0” and therefore, more power consumption can be saved than in the second example.  
      Additionally, in the aforementioned embodiment, in order to recognize the level of the remaining power of the battery, the supply voltage is monitored and judged, but the recognition section referred to in the present invention may receive a state signal indicating a battery state from the host apparatus via the interface to recognize the remaining power level.  
      Moreover, in the embodiment, the electric power is supplied from the host apparatus, but the information storage apparatus of the present invention may be provided with its own battery.  
      Furthermore, the first deceleration mode referred to in the present invention is not limited to the deceleration mode described in the embodiment. Additionally, the information storage apparatus of the present invention may constantly employ the first or second example of the deceleration mode regardless of the remaining power amount of the battery or the like.  
      Moreover, in the embodiment, the magnetooptic disk of the optical recording system is used as the information recording medium, but the information recording medium referred to in the present invention may be magnetooptic disks of respective recording systems such as a magnetooptic recording system, a phase change recording system and a magnetic recording system, other disk recording mediums such as an optical disk and a magnetic disk, and a card recording medium.  
      As described above, according to the information storage apparatus of the present invention, the battery consumption for decelerating the rotation of the information recording medium can be reduced, and as a result, the electric power for ejecting the information recording medium out of the apparatus is secured and the information recording medium can safely be taken out.