1. A write control method for a magnetoresistive random access memory including at least one memory cell, the memory cell including a magnetoresistive effect element as a storage element, the magnetoresistive effect element including a recording layer having an axis of easy magnetization and an axis of hard magnetization and of which magnetization direction is variable, a reference layer of which magnetization direction is invariable, and an insulation layer provided between the recording layer and the reference layer, the write control method comprising:
writing a datum into one memory cell, the writing of the datum including, applying a pulsative first magnetic field of a magnitude H1 substantially parallel
to the axis of easy magnetization of the recording layer and a pulsative second magnetic field of a magnitude H4 substantially parallel to the axis of hard magnetization to the recording layer so as to cause a period of the pulsative first magnetic field and a period of the pulsative second magnetic field to overlap each other,
reducing the magnitude H1 of the pulsative first magnetic field to be a magnitude H2 which is zero or more and which is less than the magnitude H1,
increasing the magnitude H2 of the pulsative first magnetic field to a magnitude H3 which is more than the magnitude H2 but equal to or less than the magnitude H1,
reducing the magnitude H4 of the pulsative second magnetic field to be zero, and
increasing the magnitude of the pulsative second magnetic field from zero to a magnitude H5 which is equal to the magnitude H4 so as to cause a period of the pulsative second magnetic field of the magnitude H5 and a period of the pulsative first magnetic field of the magnitude H3 to overlap each other.
2. The write control method according to claim 1, wherein while the pulsative first magnetic field of the magnitude H3 is applied, the pulsative second magnetic field is continuously applied to the recording layer.
3. The write control method according to claim 1, further comprising:
reducing the magnitude H4 of the pulsative second magnetic field to be zero,
wherein while the pulsative first magnetic field of the magnitude H3 is applied to the recording layer, the magnitude of the pulsative second magnetic field keeps zero.
4. A write control method for a magnetoresistive random access memory including at least one memory cell, the memory cell including a magnetoresistive effect element as a storage element, the magnetoresistive effect element including a recording layer of which magnetization direction is variable, a reference layer of which magnetization direction is invariable, and an insulation layer provided between the recording layer and the reference layer, the write control method comprising:
injecting a spin-polarized pulse current into the recording layer a plurality of times for writing a datum into one memory cell, when conducting writing by injecting a spin-polarized pulse current into the recording layer, wherein the pulses of the current are of a same polarity.
5. A magnetoresistive random access memory comprising:
a first wiring;
a second wiring;
a memory cell including a magnetoresistive effect element as a storage element, the magnetoresistive effect element being provided so as to be associated with an intersection region of the first wiring and the second wiring, the magnetoresistive effect element including a recording layer having an axis of easy magnetization and an axis of hard magnetization and of which magnetization direction is variable, a reference layer of which magnetization direction is invariable, and an insulation layer provided between the recording layer and the reference layer;
a first current generation circuit which generates a first pulse current and causes the first pulse current to flow through the first wiring in order to generate a first magnetic field substantially parallel to a direction of the axis of easy magnetization of the recording layer to be applied to the recording layer; and
a second current generation circuit which generates a second pulse current and causes the second pulse current to flow through the second wiring in order to generate a second magnetic field substantially parallel to a direction of the axis of hard magnetization of the recording layer to be applied to the recording layer, wherein
in order to write a datum into one memory cell,
the first and second current generation circuits generate the first and second pulse currents so as to cause periods of the first magnetic field and the second magnetic field to overlap each other,
then the first current generation circuit reduces a magnitude of the first pulse current so as to reduce a magnitude H1 of the first magnetic field to be a magnitude H2 which is zero or more and which is less than the magnitude H1, and increases the magnitude of the first pulse current so as to increase the magnitude H2 of the first magnetic field to a magnitude H3 and
the second current generation circuit reduces a magnitude of the second pulse current so as to reduce a magnitude H4 of the second magnetic field to be zero, and increases the magnitude of the second pulse current so as to increase the magnitude of the second magnetic field from zero to a magnitude H5 which is equal to the magnitude H4.
6. The magnetoresistive random access memory according to claim 5, comprising:
an array having a plurality of the memory cells; and
a selection circuit which selects at least one memory cell from the plurality of memory cells, wherein
the first current generation circuit generates the first pulse current so as to cause the first magnetic field to be applied to the recording layer in the selected memory cell, and
the second current generation circuit generates the second pulse current so as to cause the second magnetic field to be applied to the recording layer in the selected memory cell.
7. The magnetoresistive random access memory according to claim 5, wherein the second current generation circuit generates the second pulse current in order to cause the second magnetic field to continue to be applied to the recording layer, when the first magnetic field of the magnitude H3 is applied to the recording layer.
8. The magnetoresistive random access memory according to claim 5, wherein the second current generation circuit causes the magnitude of the second pulse current to be zero, when the first magnetic field of the magnitude H3 is applied to the recording layer.
9. The magnetoresistive random access memory according to claim 5, wherein the magnitude H3 of the first magnetic field is equal to or less than the magnitude H1 of the first magnetic field.
10. A magnetoresistive random access memory, comprising:
a first wiring;
a second wiring;
a memory cell including a magnetoresistive effect element as a storage element, the magnetoresistive effect element including a recording layer of which magnetization direction is variable, a reference layer of which magnetization direction is invariable, and an insulation layer provided between the recording layer and the reference layer, one end of the magnetoresistive effect element being electrically connected to the first wiring, the other end of the magnetoresistive effect element being electrically connected to the second wiring;
a first current generation circuit which generates a first pulse current a plurality of times and causes a spin-polarized pulse current to flow through the magnetoresistive effect element via the first wiring a plurality of times, when writing a first datum into one memory cell, wherein the pulses of the first current are of a same polarity; and
a second current generation circuit which generates a second pulse current a plurality of times and causes a spin-polarized pulse current to flow through the magnetoresistive effect element via the second wiring a plurality of times, when writing a second datum different from the first datum into one memory cell, wherein the pulses of the second current are of the same polarity.
11. The magnetoresistive random access memory according to claim 10, comprising:
an array having a plurality of the memory cells; and
a selection circuit which selects at least one memory cell from the plurality of memory cells, wherein
the first current generation circuit generates the first pulse current for the selected memory cell a plurality of times for writing the first datum into the memory cell, when conducting writing into the selected memory cell, and
the second current generation circuit generates the second pulse current for the selected memory cell a plurality of times for writing the second datum into the memory cell, when conducting writing into the selected memory cell.
12. The magnetoresistive random access memory according to claim 10, wherein a selection transistor is provided between the magnetoresistive effect element and one of the first wiring and the second wiring.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for operating a medical imaging examination apparatus comprising a plurality of apparatus subsystems, comprising:
providing a control protocol to control computer that is assigned to a scan sequence in which said control computer will control the plurality of apparatus subsystems in coordination to conduct the scan sequence to acquire medical imaging data from an examination subject;
in said control computer, determining sequence control data for said control protocol that define different functional sub-sequences of said scan sequence to be performed respectively by said apparatus subsystems;
in said control computer, assigning respectively different effective volumes of the examination subject to the respective functional sub-sequences;
in said control computer, determining current ambient conditions of said medical imaging examination apparatus that affect said sequence control data and said effective volumes;
in said control computer, calculating and storing control signals for said scan sequence dependent on said determined sequence control data, the determined effective volumes, and the determined current ambient conditions, by executing an algorithm in said control computer that optimizes the functional sub-sequences locally in the examination subject at least with regard to a sub-region of the respective effective volumes; and
in said control computer, starting said scan sequence using the stored control signals and, during said scan sequence, providing said control computer with a designation of at least one change of a sub-region of a respective effective volume, and automatically adapting said control signals for a remainder of said scan sequence dependent on said change, to maintain the optimization of the functional sub-sequences locally at least with regard to the changed sub-region.
2. A method as claimed in claim 1 comprising calculating and storing said control signals dependent on, for each sub-region to be optimized, a predetermined tolerance range that designates an amount by which the respective sub-region can be displaced, and adapting said control signals only when said change is larger than said tolerance region.
3. A method as claimed in claim 1 comprising adapting said control signals using control signals, among said stored control signals, that were calculated for a sub-region to be optimized that corresponds as closely as possible to the changed sub-region.
4. A method as claimed in claim 1 comprising calculating and storing said control signals for each functional subsequence for multiple, different effective volumes that are varies in a predetermined variation, at least with respect to sub-regions thereof, thereby producing stored control signals for respective, different variations of said sub-regions to be optimized in the respective effect volumes.
5. A method as claimed in claim 1 comprising adapting said control signals by interpolating control signals among said stored control signals.
6. A method as claimed in claim 1 comprising determining said at least one change of a sub-region of a respective effective volume continuously during said scan sequence, dependent on at least one of location and position changes of the examination subject.
7. A method as claimed in claim 1 comprising determining said at least one change of a sub-region of a respective effective volume during said scan sequence using at least one of information relating to said scan sequence, movement information detected by an external movement sensor, and movement information detected within said scan sequence.
8. A method as claimed in claim 1 comprising calculating said control signals together with a plausibility check.
9. A medical imaging examination apparatus comprising:
a plurality of apparatus subsystems;
a control computer provided with a control protocol that is assigned to a scan sequence in which said control computer is configured to control the plurality of apparatus subsystems in coordination to conduct the scan sequence to acquire medical imaging data from an examination subject;
said control computer being configured to determine sequence control data for said control protocol that define different functional sub-sequences of said scan sequence to be performed respectively by said apparatus subsystems;
said control computer being configured to assign respectively different effective volumes of the examination subject to the respective functional sub-sequences;
said control computer being configured to determine current ambient conditions of said medical imaging examination apparatus that affect said sequence control data and said effective volumes;
said control computer being configured to calculate and store control signals for said scan sequence dependent on said determined sequence control data, the determined effective volumes, and the determined current ambient conditions, by executing an algorithm in said control computer that optimizes the functional sub-sequences locally in the examination subject at least with regard to a sub-region of the respective effective volumes; and
said control computer being configured to start said scan sequence using the stored control signals and, during said scan sequence, receive a designation of at least one change of a sub-region of respective effective volume, and automatically adapt said control signals for a remainder of said scan sequence dependent on said change, to maintain the optimization of the functional sub-sequences locally at least with regard to the changed sub-region.
10. A medical imaging examination apparatus as claimed in claim 9 wherein said plurality of apparatus subsystems form a magnetic resonance scanner.
11. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a control computer of a medical imaging examination apparatus comprising a plurality of apparatus subsystems, said programming instructions causing said control computer to:
receive a control protocol that is assigned to a scan sequence in which said control computer will control the plurality of apparatus subsystems in coordination to conduct the scan sequence to acquire medical imaging data from an examination subject;
determine sequence control data for said control protocol that define different functional sub-sequences of said scan sequence to be performed respectively by said apparatus subsystems;
assign respectively different effective volumes of the examination subject to the respective functional sub-sequences;
determine current ambient conditions of said medical imaging examination apparatus that affect said sequence control data and said effective volumes;
calculate and store control signals for said scan sequence dependent on said determined sequence control data, the determined effective volumes, and the determined ambient conditions, by executing an algorithm that optimizes the functional sub-sequences locally in the examination subject at least with regard to a sub-region of the respective effective volumes; and
start said scan sequence using the stored control signals and, during said scan sequence, receive a designation of at least one change of a sub-region of a respective effective volume, and automatically adapt said control signals for a remainder of said scan sequence, dependent on said change, to maintain the optimization of the functional sub-sequences locally at least with regard to the changed sub-region.