Patent Publication Number: US-2012038306-A1

Title: Media drive device

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The entire disclosure of Japan Patent Application No. 2010-181774, filed Aug. 16, 2010, is expressly incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a media drive device that is able to reduce electricity consumption. 
     2. Description of the Related Art 
     A media drive device such as a recorder or a HDD (hard disk drive) that reads recorded data from a media or writes data onto the media by a pick-up while turning the media in certain direction is well known in prior art. For example, in the recorders, while turning DVD disks or Blue-ray disks by a spindle motor, data on the disks are read from reflection light of laser beam irradiated onto the turning media surface. 
     In addition, it is necessary to generate power in order to drive the spindle motor to turn. Technologies to generate the power to drive the motor by increasing or decreasing certain input voltage power supplied from external sources are disclosed in Japanese Patent Laid-Open gazette H11-341,323 (Japanese Patent No. 4,048,599), Japanese Patent Laid-Open 2004-064971, Japanese Patent Laid-Open 2000-149,394 or Japanese Patent Laid-Open 2009-159,810. 
     A variety of power-saving technology for products is proposed these days in order to efficiently use limited energy. Therefore it is also desirable to reduce electricity consumption of the media drive device. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention relates to a media drive device which can reduce power consumption. 
     An embodiment of my invention is a media drive device that turns a media by a motor, read data from the media and/or write data on to the media, that is comprised of a speed control unit that outputs a control pulse signal to control rotational speed of the motor and set adjusting quantity of the rotational speed by changing duty ratio of the control pulse, and a voltage up circuit that voltage up and generates driving voltage for driving the motor by switching operation that is based on the duty ratio of the control pulse. 
     In the above structured embodiment, the speed control unit controls rotational speed of the motor by changing the duty ratio of the control pulse signal. In addition, the voltage up circuit generates and outputs the driving voltage to drive the motor. And the voltage up circuit increases the supplied voltage and generates the driving voltage by switching operation that is based on the duty ratio of the control pulse. Therefore the voltage up circuit generates the driving voltage that is set to a certain amount depending on the rotational speed of the motor based on the duty ratio of the control pulse signal. Thus it is only required to generates voltage value necessary to drive the motor, and reduces useless electricity and total electricity consumption. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram explaining main structure of a recorder  10 . 
         FIG. 2  is a graph explaining speed change of a spindle motor  22   b.    
         FIG. 3  is a figure showing relationship between duty ratio of control pulse signal and voltage value of second driving voltage V 2 . 
         FIG. 4  is a block diagram explaining structure of the recorder  10  in the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One of embodiments of the media drive device may be further comprised of a constant voltage circuit that supplies a driving voltage the amount of that is higher than the driving voltage provided by the voltage up circuit, and a switching unit that makes the constant voltage circuit supply driving power to the motor when the load of the motor is high, and makes the voltage up circuit supply driving power to the motor when the motor is driven at constant rotational speed. 
     According to the present embodiment, since power supply courses can be selected depending on high load or low load of the motor, the required voltage of the motor can be properly supplied. 
     In addition, in one of the other embodiments of the invention, the voltage up circuit generates the driving voltage based on a duty ratio of the control pulse signal that it is output from the speed control unit. 
     According to the present embodiment, during the load of the motor is low while the motor rotates at constant rotational speed, if the present invention is applied, the total capacity of the voltage up circuit can be less capacity. 
     In addition, in one of the other embodiments of this invention, the speed control unit sets the duty ratio of the control pulse signal depending on the rotational speed of the motor. 
     Further, in one of more concrete embodiments, the media drive device can be further comprised of a constant voltage circuit that supplies the driving voltage that is higher than the driving voltage that the voltage up circuit supplies, and a switching unit that makes the constant voltage circuit supply driving power to the motor when the load of the motor is high, and makes the voltage up circuit supply driving power to the motor when the motor is driven at constant rotational speed; wherein the voltage up circuit generates the driving voltage based on a duty ratio of the control pulse signal that it is output from the speed control unit, and the speed control unit sets the duty ratio of the control pulse signal depending on the rotational speed of the motor. 
     Embodiments of the present invention will be explained in detail according to the following order. 
     1. The first embodiment:
         1.1. The structure of media drive devices:   1.2. The change of power supply while playing medias:       

     2. The second embodiment: 
     3. Other embodiments: 
     1. The First Embodiment 
     
         
         
           
             1.1. The Structure of Media Drive Devices: 
           
         
       
    
     Hereinafter, the first embodiment of the media drive device will be explained in detail by referring figures. In this embodiment, as an example of the media drive device, an explanation will be given based on a recorder  10 . 
       FIG. 1  is block diagram of the recorder  10 . The recorder  10  reads data recorded on a media M or write the data on the media M. The Media M is one of DVD disks, Blue-ray Disks (a registered trademark) or etc. The recorder  10  comprises a drive unit  20 , a main controller  11  and main power supply circuit  12  as shown in  FIG. 1 . The drive unit  20  performs reading data from or recording data to the media M. The main controller  11  totally performs driving control of the recorder  10 . The main power supply circuit  12  supplies drive power to the recorder  10 . 
     The main power supply circuit  12  comprises a rectifying circuit, a smoothing circuit and a depression circuit. The main power supply circuit  12  generates stabilized power based on supplied power from outside power supplies such as commercial power supplies. In this embodiment, the main power supply circuit  12  generates ‘12V’ general power supply and 5V general power supply for the drive unit  20 . The main power supply circuit  12  also generates 3.3V general power supply and 5V general power supply for the main controller  11 . 
     The main controller  11  comprises a CPU (Central processing unit), a ROM (read only memory), and a RAM (random access memory). The ROM stores programs that the CPU runs. The RAM is used as working area by the CPU. 
     The drive unit  20  is a unit that performs reading data from or recording data to the media M. The drive unit  20  comprises an optical pick-up unit  21 , a spindle unit  22 , a speed control circuit (a speed control unit)  23  and an internal power supply generating circuit  24 . 
     The optical pick-up unit  21  comprises a semiconductor laser, a light detector, and an object lens. The optical pick-up unit  21  condenses laser beam emit from the semiconductor laser by the object lens, and irradiates the laser beam on to a data recording surface of the media M. Thus the optical pick-up unit  21  performs the recording or reading data. 
     The spindle unit  22  comprises a spindle part  22   a,  a spindle motor  22   b,  and a drive circuit  22   c.  The spindle part  22   a  fixes media M with its center axis. The spindle motor  22   b  turns the spindle part  22   a.  The drive circuit  22   c  drives the spindle motor  22   b.  In this embodiment, the spindle motor  22   b  comprises a brush-less motor. The brush-less motor turns based on the detection result of a hall element. The hall element is supplied electric current from the drive circuit  22   c.  The drive circuit  22   c  changes the amount of electric current that is supplied to the spindle motor  22   b  depending on a control pulse signal output from the speed control circuit  23  (as described later), and coordinates rotational speed of the spindle motor  22   b.    
     The speed control circuit  23  outputs control pulse signal based on the rotational speed of spindle motor  22   b.  The control pulse signal is a signal to control the rotational speed of the spindle motor  22   b.  In this embodiment, the speed control circuit  23  convert rotary signal to variation of the pulses. The rotary signal corresponds to a turning of the spindle motor  22   b.  The speed control circuit  23  converts the rotary signal by F (frequency)/V (the voltage) conversion. The speed control circuit  23  performs voltage comparison, and outputs control pulse signal generated depending on the comparison result to the drive circuit  22   c  of the spindle unit  22 . Such control is so-called the FG control. In this embodiment, FG signal output from the spindle unit  22  is used as the rotary signal. The FG signal is well-known signal output depending on a number of rotation of the spindle motor  22   b.  Of course, as well as the FG signal, another rotary signal such as a signal that is output when the rotation of the spindle motor  22   b  is directly detected. 
       FIG. 2  is a graph to explain speed change of the spindle motor  22   b.  In the figure, the horizontal axis shows time, and the vertical axis shows rotational speed N (rpm). As for the control pulse signal output from the speed control circuit  23 , the duty ratio is set depending on the quantity of speed adjustment for the spindle motor  22   b.  In this embodiment, the duty ratio of the control pulse signal is set more than 50% when the spindle motor  22   b  begins to be driven (T 0 ) and during the accelerating period (T 1 ). On the other hand, the duty ratio of the control pulse signal is set to 50% while spindle motor  22   b  is driven in constant speed driving period (T 2 ). In other words, since there is no change of the rotational speed while the spindle motor  22   b  is driven in constant speed driving period (T 2 ), the duty ratio of the control pulse signal is maintained to be 50%. 
     The internal power supply generating circuit  24  generates driving voltage that will be supplied to the spindle unit  22 . The internal power supply generating circuit  24  comprises a constant voltage circuit  24   a,  a voltage up circuit  24   b,  and a switching circuit (a switching unit)  24   c.  The constant voltage circuit  24   a  generates the first driving voltage V 1  of ‘12V’ from 12V general power supply supplied by the main power supply circuit  12 . The voltage up circuit  24   b  generates the second driving voltage V 2  of ‘7.5V’ from 5V general power supply supplied by the main power supply circuit  12 . The switching circuit  24   c  switches the voltage to be supplied to the spindle unit  22  between the first driving voltage V 1  and the second driving voltage V 2 . 
     For example, the switching circuit  24   c  is equipped with operation parts such as CPU&#39;s. The switching circuit  24   c  changes the driving voltage that is supplied to the spindle unit  22  depending on the load of the spindle motor  22   b.  When the spindle motor  22   b  starts to be driven (T 0 ) and during the spindle motor  22   b  is accelerating period (T 1 ), since the switching circuit  24   c  performs above mentioned control, the constant voltage circuit  24   a  supplies the first driving voltage V 1  of ‘12V’ to the spindle unit  22 . When the spindle motor  22   b  starts to be driven (T 0 ) and during the spindle motor  22   b  is accelerated (accelerating period T 1 ), the load of the spindle motor  22   b  is high. Since the load is high, it requires much power to be supplied. On the other hand, while the spindle motor  22   b  is driven in constant speed driving period (T 2 ), since the switching circuit  24   c  performs the switching operation mentioned above, the second driving voltage V 2  of ‘7.5V’ is supplied from the voltage up circuit  24   b  to the spindle unit  22 . During the spindle motor is driven in constant speed, that is constant speed driving period (T 2 ), the load of the spindle motor  22   b  is low, and it does not require much power to be supplied. The switching control of the driving voltages by the switching circuit  24   c  is set beforehand based on a speed table of the spindle motor  22   b.    
     The voltage up circuit  24   b  comprises a separately excited oscillation circuit that generates the second driving voltage V 2  of ‘7.5V’ from the 5V general power supply supplied by the main power supply circuit  12 . Therefore, an oscillation pulse from outside is supplied to the voltage up circuit  24   b.  For example, the voltage up circuit  24   b  comprises a switching IC (integrated circuit) and a transformer T. When the switching IC is supplied of the oscillation pulse, internal transistors performs switching operation. The transformer T supplies the voltage (the second driving voltage V 2 ) to the spindle unit  22 . The voltage (the second driving voltage V 2 ) is generated by voltage up operation by the switching IC. 
     The voltage up circuit  24   b  performs switching operation based on the oscillation pulse. In this embodiment, the control pulse signal output from the speed control circuit  23  is used as the oscillation pulse by the voltage up circuit  24   b.    FIG. 3  shows the relationship between the duty ratio of the control pulse signal and the voltage value of the second driving voltage V 2 . In  FIG. 3 , the horizontal axis shows the duty ratio (a percentage) of the control pulse signal, and the vertical axis shows the voltage value (V) of the second driving voltage V 2 . Due to a plurality of parameters are set for the voltage up circuit  24   b,  the voltage up circuit  24   b  generates the second driving voltage V 2  of ‘7.5V’ when the duty ratio of the control signal (the oscillation pulse) is 50%. As a result, during the spindle motor is driven in constant speed, that is constant speed driving period (T 2 ), the internal power supply generating circuit  24  supplies the second driving voltage V 2  of ‘7.5V’ to the spindle unit  22 .
         1.2. The Switching Operation of the Power Supply at the Time of Media Reproduction:       

     Hereinafter, the switching operation of the power supply performed by the recorder  10  when the recorder  10  replays data recorded on the Media as follows. In addition, the switching operations of the power supply that is performed by the reorder  10  when the recorder  10  plays the media or records data on the media M are same. Therefore, following explanation will be the one for the former operation, and the other one for the latter one will be omitted. 
     When the main controller  11  outputs a drive instruction, the spindle unit  22  drives the spindle motor  22   b  and the media M rotates. During the period (T 0 ) in  FIG. 2 , the first driving voltage V 1  of ‘12V’ is supplied to the drive circuit  22   c  from the constant voltage circuit  24   a  under the control of the switching circuit  24   c.  During the accelerating period (T 1 ), the speed control circuit  23  outputs the control pulse signal that is set with the duty ratio depending on the number of rotations of the spindle motor  22   b  to the drive circuit  22   c.  The control pulse signal is set with the duty ratio depending on the number of rotations of the spindle motor  22   b  beforehand. Therefore the rotational speed of the spindle motor  22   b  changes from ‘0’ to ‘v1’ during the accelerating period (T 1 ). 
     When the speed of the spindle motor  22   b  reaches ‘v1’, the speed control circuit  23  maintains the duty ratio of the control pulse signal to 50%. Therefore the drive circuit  22   c  starts a constant rotational speed driving of the spindle motor  22   b  (constant rotation speed driving period T 2 ). 
     When the spindle motor  22   b  shifts to constant rotational speed driving, the switching circuit  24   c  performs switching so that the second driving voltage V 2  of ‘7.5V’ will be supplied to the drive circuit  22   c  from the voltage up circuit  24   b.  Then the control pulse signal that means the duty ratio of 50% is supplied to the switching IC of the voltage up circuit  24   b.  The voltage up circuit  24   b  performs increasing the voltage by using the control pulse signal as the oscillation pulse. Thereafter the second driving voltage V 2  of ‘7.5V’ is generated from the 5V general power supply supplied by the main power supply circuit  12 , and the second driving voltage V 2  is supplied to the spindle unit  22 . 
     In the constant rotational speed driving period (T 2 ), the spindle unit  22  will be driven by the second driving voltage V 2  of ‘7.5V’ afterward. Therefore, in the constant rotational speed driving period (T 2 ), the electricity consumption amount will be reduced than when it is driven by the first driving voltage V 1 . In addition, since the voltage up circuit  24   b  is required to generate the second driving voltage V 2  of ‘7.5V’ at the maximum, the capacity of the circuit can be less. 
     2. The Second Embodiment 
     The internal power supply generating circuit  24  can be comprised of only the voltage up circuit  24   b,  and the voltage up circuit  24   b  may generate the driving voltage of ‘7.5V’ to ‘12V’ depending on the duty ratio of the control pulse signal output by the speed control circuit  23 . 
       FIG. 4  is a block diagram explaining structure of the recorder  10  in the second embodiment. Since the spindle unit  22  needs driving voltage of ‘7.5V’ to ‘12V’ in the accelerating period T 1  of the spindle motor  22   b.  Therefore the voltage up circuit  24   b  set the parameters of the switching IC so that the voltage up circuit  24   b  generates the driving voltage of ‘7.5V’ to ‘12V’ when it oscillates in accordance with the duty ratio (for example, duty ratio of 50% to 75%) of the control pulse signal. The internal power supply generation circuit  24  will be simplified much more because of the above-mentioned composition. 
     3. Other Embodiments 
     There are various embodiments in this invention. The recorder  10  is not limited to the above mentioned recorder, and the present invention may be a television set comprising the recorder mentioned above. 
     The above explained recorder  10  can reduce the consumption of useless electricity thus reduces consumption of total electricity. This is because the voltage up circuit  24   b  generates a certain amount of the driving voltage that is set depending on the rotational speed of the spindle motor  22   b,  thus it only generates only a necessary driving voltage in order to drive the spindle motor  22   b.    
     While the invention has been particularly shown and described with respect to preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing and other changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. 
     Although the invention has been described in considerable detail in language specific to structural features and or method acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as preferred forms of implementing the claimed invention. Therefore, while exemplary illustrative embodiments of the invention have been described, numerous variations and alternative embodiments will occur to those skilled in the art. 
     It should further be noted that throughout the entire disclosure, the labels such as left, right, front, back, top, bottom, forward, reverse, clockwise, counter clockwise, up, down, or other similar terms such as upper, lower, aft, fore, vertical, horizontal, proximal, distal, etc. have been used for convenience purposes only and are not intended to imply any particular fixed direction or orientation. Instead, they are used to reflect relative locations and/or directions/orientations between various portions of an object. 
     In addition, reference to “first,” “second,” “third,” and etc. members throughout the disclosure (and in particular, claims) is not used to show a serial or numerical limitation but instead is used to distinguish or identify the various members of the group.