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JP2012175774

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2012175774
An object of the present invention is to reduce the power consumption and the number of parts
in a power generator using electromagnetic force. According to one embodiment, a motive power
generation apparatus uses a magnetic memory element such as an MTJ element (magnetic tunnel
junction element). The magnetic memory element generates a leakage magnetic field when the
magnetization state is parallel, so the leakage magnetic field acts on the permanent magnet to
generate power. Since generation of power can be performed by writing a value to the magnetic
memory element, a digital signal composed of a combination of codes “0” “1” can be used
as the drive signal. As a result, the D / A converter can be eliminated and the number of parts can
be reduced. In addition, the magnetic memory element maintains the parallel / antiparallel state
once current is supplied and the value is written, therefore there is no need to continuously apply
power to obtain power continuously, and in this aspect low power consumption Can be achieved.
[Selected figure] Figure 1
Power generation device, sound reproduction device, injection device, position control device,
optical switching device
[0001]
The present invention relates to a power generation device using a magnetic memory element,
and an acoustic reproduction device, an injection device, a position control device, and an optical
switching device using the power generation device.
[0002]
JP, 9-233800, A JP, 2007-218241, A
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1
[0003]
2. Description of the Related Art Conventionally, a power generation device utilizing an
electromagnetic force, such as a voice coil motor, has been widely used.
In these power generators, current is supplied to the drive coil to generate a magnetic field to
obtain a driving force.
[0004]
However, such conventional power generators can not continue to generate power unless power
is supplied.
If this point can be improved, it can greatly advance in terms of reducing power consumption.
[0005]
Further, in the conventional power generation device, even if the control signal is generated as a
digital signal, a configuration in which the control signal is D / A converted and given to a driver
for driving the power generation device is general. That is, since the D / A converter intervenes, it
is disadvantageous in terms of downsizing of the drive portion and reduction of the number of
parts, which hinders reduction of the product cost.
[0006]
This art makes it a subject to solve the above-mentioned problem, and constitutes a power
generation device as follows. That is, in the power generation device of the present technology,
the magnetization state of the magnetic memory element can be determined by flowing a current
in a direction according to the code "0" "1" of the input signal to the magnetic memory element.
And an element drive unit that changes parallel / antiparallel. Furthermore, according to the
movement of the magnetic body, the magnetic body is configured to be driven according to a
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leakage magnetic field generated in the magnetic memory element when the magnetic body is in
a parallel state. And a power generation unit that generates a power.
[0007]
Here, the magnetic memory element refers to a storage layer (magnetization free layer) in which
the direction of magnetization changes when a write current / reverse current flows, and the
direction of magnetization changes according to the write current / reverse current. And at least
a magnetization fixed layer (reference layer) configured to cause a change in the electrical
resistance value due to a change in the magnetization direction of the storage layer with respect
to the magnetization direction of the magnetization fixed layer. It refers to an element configured
to indicate the holding state of different values by change. In such a magnetic memory element, a
leakage magnetic field is generated when the directions of the magnetic fields in the
magnetization fixed layer and the storage layer coincide with each other (a so-called parallel
state). On the other hand, in the state where the direction of the magnetic field is opposite
between the magnetization fixed layer and the storage layer (a so-called antiparallel state), the
magnetic fields cancel each other, and a leakage magnetic field is not generated. By driving the
magnetic body according to the leakage magnetic field generated in the former parallel state,
power is generated. At this time, the magnetic memory element maintains the above anti-parallel
state or parallel state if writing a value into it once (that is, if the current as the above-mentioned
write current or reversal current flows). That is, once the current is made to flow and transition
to the above-described parallel state, the above-mentioned leakage magnetic field continues to be
generated. As understood from this, according to the power generation device of the present
technology using a magnetic memory element, it is possible to eliminate the need to continuously
supply power in order to obtain power continuously. That is, it is possible to reduce power
consumption in this aspect. In addition, the value rewriting, that is, the switching between the
antiparallel state and the parallel state, need only be given the write current / reversal current,
and can be driven by a digital signal formed of a combination of codes “0” and “1” is there.
That is, there is no need to intervene the D / A converter in driving, and the number of parts can
be reduced and the circuit configuration can be simplified in this respect. In addition, the
magnetic memory element can be rewritten at high speed. Therefore, according to the power
generation device of the present technology using the magnetic memory element, high speed
response can be realized and wide band operation can be realized.
[0008]
According to the present technology, it is possible to realize a power generation device with low
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power consumption and a simple configuration. Furthermore, according to the present
technology, it is possible to realize a power generation device capable of high speed response
and capable of wide band operation.
[0009]
It is a figure showing the 1st example of composition of a power generation device of an
embodiment. It is a figure for demonstrating the storage principle of a magnetic memory
element. It is a figure for demonstrating the motive power generation principle of the motive
power generation device of embodiment. It is a figure showing the 2nd example of composition
of a power generation device of an embodiment. It is the timing chart which showed the
operation waveform of each part in the example of the 2nd composition. It is a figure for
demonstrating the structural example for obtaining a bigger driving force. It is the figure which
showed the structure of the sound reproduction apparatus which applied the motive power
generation apparatus of embodiment. It is the figure which showed the structure of the
conventional full digital sound reproduction apparatus. It is a figure showing composition of a
micro injector to which a power generation device of an embodiment is applied. It is a figure
showing composition of a servo control unit to which a power generation device of an
embodiment is applied. It is the figure which showed the structure of the optical switch which
applied the motive power generation device of embodiment.
[0010]
Hereinafter, embodiments according to the present technology will be described. The description
will be made in the following order. <1. Power Generation Device of Embodiment> [1-1. First
Configuration Example] [1-2. Second configuration example] [1-3. Configuration Example for
Increasing Driving Force] <2. Application Example of Power Generation Device of Embodiment>
[2-1. Sound reproduction device (micro speaker)] [2-2. マイクロインジェクタ] [2-3. Servo
control system] [2-4. Optical switch] <3. Modified example>
[0011]
<1. Power Generation Device of Embodiment> [1-1. First Configuration Example] FIG. 1 shows
a first configuration example of a power generation device according to an embodiment. First, in
the present embodiment, a so-called MTJ element (MTJ: Magnetic Tunnel Junction) is used as a
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magnetic memory element.
[0012]
Here, as a memory element, NOR flash memory, DRAM, etc. are widely spread at present, but as a
next-generation memory element replacing them, FeRAM (Ferroelectric Random Access
Memory), MRAM (Magnetic Random Access Memory), PCRAM Development of (Phase-Change
Random Access Memory) has been advanced, and some of them have already been put to
practical use.
[0013]
Above all, MRAM is capable of high-speed and almost infinite (10 <15> times or more) rewriting
to store data according to the magnetization direction of the magnetic substance, and is already
used in the field of industrial automation, aircraft, etc. .
[0014]
In the MRAM, a current magnetic field application method that changes the magnetization
direction (that is, changes the stored value) by applying to the magnetic memory element a
current magnetic field generated by supplying a current to a wire disposed in the vicinity of the
magnetic memory element And the magnetization reversal type in which the magnetization
direction is changed by supplying a current directly to the magnetic memory element.
Among these, as the latter magnetization reversal method, there is a so-called spin torque
magnetization reversal method, and the spin torque magnetization reversal method is known to
be advantageous in terms of reducing power consumption and the like.
[0015]
Here, in the spin torque magnetization inversion method, when spin-polarized electrons passing
through a magnetization fixed layer whose magnetization direction is fixed approach a storage
layer (a magnetic layer whose magnetization direction is made variable: also referred to as a free
layer) By applying a torque to the storage layer (also referred to as a spin transfer torque), and
supplying a current equal to or greater than a predetermined threshold value in the direction in
which the magnetization fixed layer and storage layer are stacked. It utilizes the property that the
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magnetization direction is reversed.
At this time, rewriting of "0" "1" as stored information is performed by changing the polarity of
the current.
[0016]
An MRAM utilizing spin torque magnetization reversal is called ST-MRAM (Spin Torque-Magnetic
Random Access Memory). In addition, spin torque magnetization reversal is also referred to as
spin injection magnetization reversal.
[0017]
In the spin torque magnetization reversal method, an MTJ element (MTJ: Magnetic Tunnel
Junction) is often used as the magnetic memory element as in the case of the current magnetic
field application method described above. Here, the MTJ element has an insulating layer formed
of an insulator thin film as an intermediate layer disposed between the storage layer and the
magnetization fixed layer, as described in, for example, the following reference: A high
magnetoresistance ratio (MR ratio) can be realized by the magnetic tunnel junction effect by
providing the insulating layer (see, in particular, [0002] to [0008] of Reference 1). Reference 1:
JP-A 2002-314164 Reference 2: Reference 2: JP-2008-227388
[0018]
In FIG. 1, the magnetic memory element by such an MTJ element is described as MTJ1. A drive
current corresponding to the input signal is supplied to the MTJ 1 by the drive unit 2 in the
drawing. Specifically, the drive current in this case is made to flow in the stacking direction of the
above-described magnetization fixed layer, intermediate layer (insulation layer), and storage layer
constituting the MTJ 1 (current Ip in FIG. ).
[0019]
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Further, the power generating device of the present embodiment is provided with the permanent
magnet 3 and the spring 4 for suspending the permanent magnet 3 with the wall surface 5. Here,
the wall surface 5 is, for example, a surface connected to the housing side of a device
incorporating the power generation device, and the relative positional relationship with the MTJ
1 is fixed.
[0020]
In such a configuration, a leakage magnetic field is generated in the MTJ 1 in response to the
drive unit 2 flowing a drive current according to the input signal to the MTJ 1, and the
permanent magnet 3 is driven to the wall surface 5 according to the generation of the leakage
magnetic field. Be done. That is, power is generated. Hereinafter, the operation principle of the
power generation apparatus according to such an embodiment will be described with reference
to FIGS. 2 and 3.
[0021]
First, the storage principle of the MTJ 1 will be described with reference to FIG. As illustrated, the
MTJ 1 at least includes a magnetization fixed layer 1A, a storage layer 1B, and an insulating layer
1C as an intermediate layer provided therebetween. Here, it is assumed that the direction of
magnetization M_s of the magnetization fixed layer 1A is fixed in the right direction in the
drawing, for example, as illustrated.
[0022]
As a current flowing in the stacking direction of the MTJ 1, for example, as shown in FIG. 2A,
when a current Ip flowing downward in the plane of the paper flows, the magnetization direction
M_f of the storage layer 1B as the free layer is as shown in FIG. As shown in), it changes in the
same direction as the magnetization direction of the magnetization fixed layer 1A (a so-called
parallel state). On the other hand, when a current I-ap (that is, a current of the opposite polarity
to the current Ip) flows upward in the drawing as shown in FIG. 2B with respect to the MTJ1, the
magnetization direction M_f of the storage layer 1B is shown. It will be reversed from the case of
2 (a) (a so-called antiparallel state). At this time, the reversal of the magnetization direction M_f
of the storage layer 1B occurs by flowing a current exceeding a predetermined threshold as the
current I-ap (or current Ip).
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[0023]
In the parallel state shown in FIG. 2A and the antiparallel state shown in FIG. 2B, a difference in
electric resistance value of the MTJ 1 is generated due to a so-called magnetoresistance effect.
The difference between the resistance values indicates the difference between the holding state
of the code “1” and the holding state of the code “0”. Here, assuming that the state of FIG.
2A is the storage state of code “1” and the state of FIG. 2B is the code “0”, current I-p is the
write current and current I-ap is the reverse. It can be said that current.
[0024]
FIG. 3 is a diagram for explaining the power generation principle of the power generation device
of the embodiment. FIG. 3A shows the case where the magnetization of the MTJ 1 is in the
parallel state (memory state of code “1”), and FIG. 3B shows the case in the antiparallel state
(memory state of code “0”). There is.
[0025]
In FIG. 3A, when the magnetizations of the MTJ1 are parallel, the direction of magnetization M_s
of the magnetization fixed layer 1A and the direction of magnetization M_f of the storage layer
1B coincide with each other, and a leakage magnetic field is generated in the MTJ1. For this
reason, as shown, the permanent magnet 3 is driven to the wall surface 5 side (that is, driven
away from the MTJ 1). On the other hand, in the antiparallel state of FIG. 3B, the magnetization
direction M_f of the storage layer 1B is opposite to the magnetization direction M_s of the
magnetization fixed layer 1A so that the magnetic fields cancel each other, and the leakage of the
MTJ1 occurs. The magnetic field will be much smaller (or not). Therefore, in this case, the
permanent magnet 3 is driven in the direction approaching the MTJ 1 by the stress of the spring
4.
[0026]
In this manner, the reciprocation of the permanent magnet 3 can be obtained by writing
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(rewriting) the code "0" "1" to the MTJ1. That is, power can be generated.
[0027]
Here, as understood from the above description, in the case of this example, in order to drive the
permanent magnet 3 to the wall 5 side, it is preferable to flow the current I-p to the MTJ 1 and
write the code "1". Also, in order to drive the permanent magnet 3 to the MTJ 1 side, the current
I-ap may be supplied to the MTJ 1 and the code "0" may be written. In response to this, the drive
unit 2 in this case flows the current I-p to the MTJ 1 (applying the drive voltage of positive
polarity) according to the code "1" (for example, High) of the input signal, and the code of the
input signal According to “0” (for example, High), the current I-ap is supplied to the MTJ 1 (a
negative drive voltage is applied).
[0028]
According to the power generation device as the embodiment as described above, once the value
is written in the MTJ 1 (that is, if the current I as the write current or the reversal current flows),
the above-mentioned parallel or antiparallel state is maintained. Therefore, once the current I-ap
is supplied to the MTJ 1 to make a transition to the parallel state, a leakage magnetic field
continues to be generated. Therefore, according to the power generation device of the present
embodiment, there is no need to continuously supply power to the MTJ 1 to continuously apply
the driving force to the permanent magnet 3 (that is, to obtain continuous power). It can be. That
is, it is possible to reduce power consumption in this aspect.
[0029]
In addition, when rewriting the value, that is, switching between the parallel state / anti-parallel
state, a current exceeding a predetermined threshold value may be applied as the write current /
reversal current, and driving with a digital signal (binary signal) is possible. . That is, there is no
need to interpose the D / A converter in driving, and in this respect, the number of parts can be
reduced, the circuit configuration can be simplified, and the cost can be reduced.
[0030]
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Here, the magnetic memory elements including the MTJ 1 have a characteristic that the change
in value is effective only when the amount of current (or the magnetic force in the case of the
magnetic application type) exceeds a certain threshold. From this characteristic, the power
generation device of the present embodiment using a magnetic memory element also has an
advantage of being excellent in noise resistance.
[0031]
Further, as described above, the magnetic memory element can be rewritten at high speed.
Therefore, according to the power generating device of the present embodiment using the
magnetic memory element, high speed response is possible and wide band operation is possible. .
[0032]
It should be noted that the magnetic memory element used in the present technology is not
limited to a magnetic tunnel junction element such as the MTJ 1 including an insulating layer
between the storage layer and the magnetization fixed layer, as described for confirmation. .
Here, the magnetic memory element in the present technology means a storage layer
(magnetization free layer) in which the direction of magnetization changes when a write current /
reverse current flows, and the direction of magnetization according to the write current / reverse
current. And at least a magnetization fixed layer (reference layer) configured so as not to change,
and a change in the magnetization direction of the storage layer with respect to the
magnetization direction of the magnetization fixed layer causes a change in electrical resistance,
It is sufficient if the element is configured to indicate the holding state of different values by
changing the value.
[0033]
Here, in the power generation apparatus according to the embodiment, as a method of driving
the permanent magnet 3, binary drive in which the position of the permanent magnet 3 is simply
displaced by two values of the upper limit position / lower limit position, and PWM (Pules Width
Two types can be mentioned, namely, displacement amount variable drive that enables
adjustment of the drive amount of the permanent magnet 3 using so-called 1-bit digital signals
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such as Modulation) and PDM (Pulse Density Modulation) signals. Selection of these drive
methods can be performed by, for example, a suspension method of the spring 4. Specifically, in
the case of the above binary drive, the position of the permanent magnet 3 is closest to the wall
surface 5 when the MTJ 1 is in parallel simply by using a spring having a relatively fast response
speed as the spring 4 or the like. In the anti-parallel state, the permanent magnet 3 may be
positioned so as to be closest to the MTJ 1 (lower limit position).
[0034]
On the other hand, in the case of variable displacement drive, for example, the pulse duty or the
pulse density is 50%, in other words, the MTJ1 is in parallel or antiparallel within a unit time as
one cycle of the PWM signal or PDM signal. It is assumed that the spring 4 is selected (e.g.,
damping characteristics) so that the permanent magnet 3 is at an intermediate position (i.e., an
equilibrium point of movement of the permanent magnet 3 is obtained) in a state where the time
length becomes half. Just do it.
[0035]
[1
-2.
Second Configuration Example Next, a second configuration example of the power generation
device of the present embodiment will be described. In the second configuration example, driving
of the MTJ 1 is realized by unipolar driving. FIG. 4 shows a configuration example of a power
generation device as a second configuration example. In FIG. 4, the same parts as those already
described above are denoted by the same reference numerals, and the description thereof will be
omitted.
[0036]
As shown, in the second configuration example, a drive unit 2 'is provided instead of the drive
unit 2 provided in the first configuration example, and a capacitor C1 is connected in series to
the MTJ 1 . As shown, the capacitor C1 is inserted between the MTJ1 and the ground (GND).
[0037]
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In this case, when the input signal is High, the drive unit 2 ′ is configured to flow the current Ip
(write current) to the [MTJ1-capacitor C1] series connection circuit.
[0038]
FIG. 5 is a timing chart showing operation waveforms of each part in the second configuration
example.
Specifically, the waveforms of the input signal shown in FIG. 4, the discharge current of the
capacitor C1, and the magnetization state of the MTJ 1 are shown. Note that this figure illustrates
the case where the input signal is a PWM signal. Further, in FIG. 5, in the magnetization state of
the MTJ 1, “P” in the drawing represents a parallel state, and “AP” represents an antiparallel
state.
[0039]
In FIG. 5, when the input signal is High, the drive section 2 'causes the current I-p as the write
current to flow to the [MTJ1-capacitor C1] series connection circuit. As a result, the MTJ1
changes to the parallel state (P), and in this case, the capacitor C1 is also charged.
[0040]
When the input signal becomes low, the supply of the current Ip by the drive unit 2 'is stopped.
In response to this, the discharge of the capacitor C1 is started. That is, as a result, the current Iap shown in FIG. 4, that is, the reverse current to the MTJ 1 flows. As a result, in the period in
which the input signal is low, the magnetization state of the MTJ 1 is in the antiparallel state
(AP).
[0041]
As understood from this, according to the second configuration example in which the capacitor
C1 is connected in series to the MTJ1, the discharge of the capacitor C1 allows the current I-ap,
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which is an inversion current, to flow to the MTJ1. Therefore, it is not necessary for the drive
unit 2 'to perform the drive on the negative polarity side for flowing the reverse current as in the
case of the first configuration example. That is, it is only necessary to drive on the positive
polarity side for flowing the write current (Ip) in accordance with the period in which the input
signal is High. At this time, when the input signal is low, the output signal level by the drive unit
2 ′ may be 0 level (GND level), and hence the power consumption in the period is reduced.
[0042]
Here, the electrostatic capacitance (capacitance) of the capacitor C1 is set to a value
corresponding to the total amount of charges causing a change from the parallel state to the
antiparallel state of the MTJ 1. For example, if the MTJ 1 has a size of about 100 nm in diameter,
for example, a proper inversion current level of about 100 μA is required. When this is given as
a pulse, the inversion is completed in about 20 ns. The voltage applied at this time is about 1.2 V.
Therefore, the necessary capacitance of C1 can be estimated to be 120 fF from C = QV. The
upper limit of the drive frequency under this condition can be calculated to be about 500 MHz.
[0043]
[1
-3. Configuration Example for Increasing Driving Force] Here, depending on the application of
the power generation device of the embodiment, it may be assumed that a sufficient driving force
can not be obtained with only one MTJ 1. In such a case, the drive power may be adjusted by
appropriately adopting, for example, the configuration shown in FIG. Although FIG. 6 exemplifies
a case in which the capacitor C1 is connected as in the second configuration example, it is
naturally applicable to the case where the first configuration example is adopted. .
[0044]
FIG. 6A shows a configuration in which a plurality of [MTJ-capacitor C1] series connection
circuits are provided in parallel on one substrate 6. Further, FIG. 6B shows a configuration in
which a desired driving force is obtained by forming a laminate 7 in which a plurality of
substrates 6 shown in FIG. 6A are stacked.
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[0045]
<2. Application Example of Power Generation Device According to Embodiment> A specific
application example of the power generation device according to the embodiment described
above will be exemplified below. In each of the following application examples, it is assumed that
the power generation device of the second configuration example (having [MTJ1-capacitor C1]
series connection circuit) shown in FIG. 4 is used as the power generation device of the
embodiment. Although illustrated, of course, the power generation device of the first
configuration example can also be used.
[0046]
[2
-1. Sound Reproducing Device (Micro Speaker)] FIG. 7 shows a configuration of a sound
reproducing device to which the power generation device of the embodiment is applied. First, a
DSP (Digital Signal Processor) 8 in the figure is an audio signal for applying equalization
processing, various acoustic effects such as a reverberation effect, etc. to an input audio signal
(for example, digital audio signal such as linear PCM). It is possible to apply processing. An audio
signal subjected to audio signal processing by the DSP 8 is subjected to ΔΣ modulation by the
ΔΣ modulator 9 and converted into a PWM signal.
[0047]
The PWM signal obtained by the ΔΣ modulator 9 is supplied to the micro-speaker 10 provided
with a [MTJ1-capacitor C1] series connection circuit. The micro speaker 10 includes a [MTJ1capacitor C1] series connection circuit, and a sound output unit 10A disposed in the vicinity of
the MTJ1.
[0048]
Although not shown, the sound output unit 10A vibrates and emits sound by the permanent
magnet (magnet) disposed in the vicinity of the MTJ 1 and the power generated by the
permanent magnet being driven according to the leaked magnetic field of the MTJ 1 And a
diaphragm. In this case, as a configuration for vibrating the diaphragm, as shown in FIG. 1 and
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FIG. 4, the configuration may be such that vibration is provided using the power of the
permanent magnet suspended by the spring 4; Alternatively, the permanent magnet may be fixed
directly to the diaphragm to give vibration. When the latter configuration is adopted, the
diaphragm also functions as the spring 4, that is, as an elastic body that pushes the permanent
magnet back to the MTJ 1 side when the MTJ 1 is in the antiparallel state.
[0049]
In the case of this application example, the ΔΣ modulator 9 corresponds to the drive unit 2 ′
described above in the sense that it drives the MTJ 1.
[0050]
Here, FIG. 8 shows a configuration of a conventional full digital sound reproducing apparatus.
As shown in FIG. 8, in the conventional full digital sound reproducing apparatus, the switching
amplifier 11 switches the input voltage Vin based on the PWM signal obtained by the ΔΣ
modulator 9, and the switching output is LPF (low pass filter) The speaker 13 is driven by the
signal obtained through 12).
[0051]
According to the configuration of such a conventional full digital audio reproduction device,
although the D / A converter is not required in the output stage, the switching amplifier 11 and
the LPF 12 are required in comparison with the configuration shown in FIG. I understand. That is,
as understood from this point, according to the sound reproducing apparatus to which the power
generating apparatus of the present embodiment is applied, the configuration is simplified and
the number of parts is reduced even in comparison with the conventional full digital sound
reproducing apparatus. It will be possible to reduce and miniaturize, and further reduce product
costs. In addition, if the switching amplifier unit 11 and the LPF 12 are unnecessary, high
efficiency and low noise can be achieved.
[0052]
Note that, in the case of this application example, as a driving method for the permanent magnet
in the sound emitting unit 10A, the above-described displacement amount variable driving is
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realized in the case of this application example for confirmation.
[0053]
[2
-2.
Microinjector] FIG. 9 shows the configuration of a microinjector 20 to which the power
generation device of the embodiment is applied. As shown, in the microinjector 20, the injection
section 21 having an injection port with the [MTJ1-capacitor C1] series connection circuit, the
permanent magnet 3 and the spring 4, and the injection port of the injection section 21 opened /
closed. And a sliding lid 22 for the purpose. As shown, one end of the slide lid 22 is connected to
the permanent magnet 3, and the other end is connected to the wall 5 via the spring 4. The
position of the permanent magnet 3 is displaced in the left and right direction of the paper
surface according to the driving of the MTJ 1 by the drive unit 2 ′, and the slide lid 22 is also
displaced in the left and right direction of the paper surface in conjunction with this. You can
open / close your mouth.
[0054]
In the case of this application example, as the driving method of the permanent magnet 3, it is
conceivable to adopt either of the above-described binary driving or displacement amount
variable driving. That is, if the open state / closed state of the injection port is simply switched
alternatively, the above-described binary drive may be adopted, and if the injection amount can
be adjusted, It is sufficient to adopt a variable displacement drive of
[0055]
[2
-3. Servo Control System] FIG. 10 shows a configuration of a servo control unit 25 to which the
power generation device of the embodiment is applied. As shown, the servo control unit 25 is
provided with the [MTJ1-capacitor C1] series connection circuit, the permanent magnet 3 and
the spring 4 in the same manner as the power generating device shown in FIG. And a position
detection unit 27 configured to detect an error between the position of the drive target 26 and
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the target position of the drive target 26, and the servo filter 28. And a PWM modulator 29 are
provided. The detection signal from the position detection unit 27 is input to the servo filter 28
as a feedback signal. The servo filter 28 generates a servo signal for causing the position of the
driven object 26 to coincide with the target position by performing predetermined filtering
(servo calculation) on the feedback signal. The PWM modulator PWM modulates the servo signal
obtained by the servo filter 28 and drives the MTJ 1 with the PWM signal obtained thereby.
Specifically, the MTJ1 is driven to flow only the current I-p to be flowed corresponding to the
period in which the PWM signal is High.
[0056]
With such a configuration, servo control (feedback control) for making the position of the driven
object 26 constant at the target position is realized.
[0057]
Here, in the above description, although a specific application example of the servo control unit
25 is not mentioned, for example, in a case where the servo control unit in an optical disk system
is used as an example, the driven object 26 is an objective lens. The position detection unit 27
corresponds to a portion for generating an error signal such as a tracking error signal or a focus
error signal (a photodetector for receiving light reflected from an optical disc, an operation unit
for calculating an error signal from the light reception signal, etc. And the equivalent of
[0058]
Although the drive target 26 is illustrated as being directly connected to the permanent magnet 3
in FIG. 10, the drive target 26 may of course be connected to the permanent magnet 3 through
some member.
[0059]
[2
-4.
Optical Switch] FIG. 11 shows a configuration of an optical switch 30 to which the power
generation device of the embodiment is applied.
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In the optical switch 30, the drive unit 2 ', the MTJ 1, the capacitor C1, the permanent magnet 3
and the spring 4 are provided as in the case of FIG.
In this case, the movable switch 31 is provided as a mechanical mechanism for switching the
light guided by the optical path 32 in the drawing to either the optical path 33A or the optical
path 33B.
[0060]
The movable switch 31 is configured to selectively guide the light guided by the optical path 32
to either the optical path 33A or the optical path 33B by applying power according to the
displacement of the permanent magnet 3 in the left-right direction in the drawing. It is done.
That is, one of the light path 33A and the light path 33B is selected.
[0061]
In the case of this application example, the above-mentioned binary drive may be adopted as a
drive method of the permanent magnet 3.
[0062]
<3.
Modifications> Although the embodiments according to the present technology have been
described above, the present technology should not be limited to the specific examples described
above. For example, although the power generation device has the spring 4 for suspending the
permanent magnet 3 in the above description, the power generation device of the present
technology does not necessarily have the spring 4. For example, when the permanent magnet 3
is configured to be driven by the MTJ 1 in the direction opposite to the direction in which gravity
acts, the above-described binary drive can be achieved by providing a stopper that determines at
least the lower limit position of the permanent magnet 3. Or, displacement variable drive can be
realized.
[0063]
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In the above description, the magnetization direction of the magnetic memory element is set to
be parallel to the in-plane direction. However, the magnetization direction of the magnetic
memory element can be set to be perpendicular to the in-plane direction.
[0064]
Further, application examples of the power generation device according to the present
technology are not limited to those described above, and are merely representative examples.
For example, application to various switches other than the optical switch 30 and various
actuators is possible. Moreover, the application to a motor, a generator, etc. is also possible.
[0065]
Reference Signs List 1 MTJ, 1 A magnetization fixed layer, 1 B storage layer, 1 C insulating layer,
M_s, M_f magnetization direction, 2, 2 ′ driving unit, 3 permanent magnet, 4 spring, 5 wall
surface, C1 capacitor, 6 substrate, 7 laminate, 8 DSP, 9 ΔΣ modulator, 10 micro speaker, 10 A
sound output unit, 20 micro injector, 21 injection unit, 22 slide lid, 25 servo control unit, 26
drive object, 27 position detection unit, 28 servo filter, 29 PWM modulation , 30 light switches,
31 movable switches, 32, 33A, 33C light path
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