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1. 发明授权

US5864275A Opposed magnet-type magnetic circuit assembly with permanent magnets 失效
公开(公告)号：US5864275A
公开(公告)日：1999-01-26
申请号：US703450
申请日：1996-08-27
申请人： Ken Ohashi , Yuhito Yoneda , Koji Miyata , Yuji Inoue
发明人： Ken Ohashi , Yuhito Yoneda , Koji Miyata , Yuji Inoue
IPC分类号： G01R33/383 , G01R33/3873 , G01R33/20
CPC分类号： G01R33/383 , G01R33/3873
摘要： Proposed is an improvement in an opposed-magnet magnetic circuit assembly with permanent magnets suitable for use, for example, in an MRI instrument comprising a pair of upper and lower permanent magnets to form a magnetic-field gap space therebetween, a pair of magnetic-field adjustment plates each on the surface of the permanent magnet to face the gap space and a pair of back yokes each on the back surface of the permanent magnet. According to the first aspect of the invention, a combination of a gradient coil and a shimming plate is mounted on the magnetic-field adjustment plate with intervention of several pieces of shim members and, further, another set of second shim members are bonded to the surface of the shimming plate facing the gap space with an object to improve the uniformity of the magnetic field in the gap space. According to the second aspect of the invention, which is directed to the problem of alleviation of the oppressive sense received by the patient lying in the MRI instrument due to his encaved condition, the back yokes are magnetically and mechanically connected with two and only two columnar connecting yokes each of which has a smaller cross section in the center portion than in the upper and lower end portions in order to ensure lateral openness on both sides of the patient. Preferable configurations are also proposed for the back yokes and the permanent magnets.

2. 发明授权

US5774034A Magnet assembly in MRI instrument 失效
标题翻译： MRI仪器中的磁铁组件
公开(公告)号：US5774034A
公开(公告)日：1998-06-30
申请号：US706349
申请日：1996-08-30
申请人： Yuhito Yoneda , Koji Miyata , Ken Ohashi , Dai Higuchi
发明人： Yuhito Yoneda , Koji Miyata , Ken Ohashi , Dai Higuchi
IPC分类号： G01R33/385 , A61B5/055 , G01R33/383 , G01R33/3873 , G01R33/565 , G01V3/00
CPC分类号： G01R33/383 , G01R33/3873 , G01R33/56518
摘要： Proposed is an improvement in a magnet assembly of an MRI instrument of the permanent magnet type comprising a pair of permanent magnets facing each other and forming a magnet gap therebetween. A pair of pole pieces each of which are mounted on one of the permanent magnets and a pair of gradient-field coils each of which are mounted on one of the pole pieces where both the pole pieces and coils face the gap. With an object of the invention to cancel the adverse influences caused by the residual magnetization of the pole pieces by the gradient magnetic field generated in the gradient-field coils. The invention proposes providing a pair of magnetic-field compensation members each on one of the gradient-field coils so that the residual magnetization in the compensation members generates a magnetic field which is compensatory for the magnetic field due to the residual magnetization in the pole pieces.
摘要翻译：提出了一种永磁体MRI仪器的磁体组件的改进，其包括彼此面对的一对永磁体，并在其间形成磁隙。一对极片安装在一个永磁体上，一对倾斜磁场线圈分别安装在磁极片之一上，两个极片和线圈都面对间隙。本发明的目的是通过在梯度场线圈中产生的梯度磁场来消除由极片的剩余磁化引起的不利影响。本发明提出在梯度场线圈中的一个上提供一对磁场补偿元件，使得补偿元件中的剩余磁化产生由于极片中的剩余磁化而导致的磁场补偿的磁场。

3. 发明授权

US5825187A Magnetic circuit system with opposite permanent magnets 失效
标题翻译：具有相对永久磁铁的磁路系统
公开(公告)号：US5825187A
公开(公告)日：1998-10-20
申请号：US843053
申请日：1997-04-11
申请人： Ken Ohashi , Yuhito Yoneda , Koji Miyata , Dai Higuchi
发明人： Ken Ohashi , Yuhito Yoneda , Koji Miyata , Dai Higuchi
IPC分类号： H01F7/02 , A61B5/055 , G01R33/383 , G01R33/3873 , G01V3/00
CPC分类号： G01R33/383 , G01R33/3873
摘要： The present invention provides is an improvement in a magnetic circuit system with a pair of opposite permanent magnets to construct an MRI instrument comprising a pair of upper and lower permanent magnets connected with yokes to form an air gap space therebetween, in which the patient under MRI inspection is kept lying, a pair of shimmed pole pieces each mounted on the permanent magnet to face the air gap and a pair of gradient coils each mounted on the shimmed pole piece to face the air gap. The improvement comprises mounting a cancellation magnetic plate, which is a thin plate of a magnetic material having a coercive force of 0.1 to 500 Oe, on the gradient coil to face the air gap with an object to cancel the residual magnetization of the shimmed pole piece by the gradient magnetic field. The cancellation magnetic plate has a thickness not exceeding 0.5 mm and has a base area which is 5 to 75% relative to the base area of the gradient coil.
摘要翻译：本发明提供了具有一对相对的永磁体的磁路系统的改进，以构造MRI仪器，其包括一对与轭架连接的上下永磁体，以在其间形成气隙空间，患者在MRI下检查保持躺着，一对分别安装在永久磁铁上以面对气隙的垫片极片和一对梯度线圈，每个梯度线圈都安装在垫片极片上以面对气隙。改进之处在于，将梯度线圈上具有矫顽力为0.1〜500Oe的磁性材料的薄板的抵消磁性板安装在与物体相对的气隙上，以抵消该偏振极片的剩余磁化强度通过梯度磁场。取消磁性板的厚度不超过0.5mm，基底面积相对于梯度线圈的基面积为5〜75％。

4. 发明授权

US5963117A Opposed magnet-type magnetic circuit assembly with permanent magnets 失效
标题翻译：具有永久磁铁的磁铁型磁路组件
公开(公告)号：US5963117A
公开(公告)日：1999-10-05
申请号：US206291
申请日：1998-12-07
申请人： Ken Ohashi , Yuhito Yoneda , Koji Miyata , Yuji Inoue
发明人： Ken Ohashi , Yuhito Yoneda , Koji Miyata , Yuji Inoue
IPC分类号： G01R33/383 , G01R33/3873 , H01F7/02
CPC分类号： G01R33/383 , G01R33/3873
摘要： Proposed is an improvement in an opposed-magnet magnetic circuit assembly with permanent magnets suitable for use, for example, in an MRI instrument comprising a pair of upper and lower permanent magnets to form a magnetic-field gap space therebetween, a pair of magnetic-field adjustment plates each on the surface of the permanent magnet to face the gap space and a pair of back yokes each on the back surface of the permanent magnet. According to the first aspect of the invention, a combination of a gradient coil and a shimming plate is mounted on the magnetic-field adjustment plate with intervention of several pieces of shim members and, further, another set of second shim members are bonded to the surface of the shimming plate facing the gap space with an object to improve the uniformity of the magnetic field in the gap space. According to the second aspect of the invention, which is directed to the problem of alleviation of the oppressive sense received by the patient lying in the MRI instrument due to his encaved condition, the back yokes are magnetically and mechanically connected with two and only two columnar connecting yokes each of which has a smaller cross section in the center portion than in the upper and lower end portions in order to ensure lateral openness on both sides of the patient. Preferable configurations are also proposed for the back yokes and the permanent magnets.
摘要翻译：提出了一种具有永磁体的对置磁体磁路组件的改进，该永磁体适用于例如在包括一对上下永磁体的MRI仪器中以在其间形成磁场间隙空间的一对磁 - 在永磁体的表面上分别面对间隙空间的磁场调整板以及永久磁铁背面上的一对后轭。根据本发明的第一方面，梯度线圈和匀场板的组合通过几片垫片构件的介入安装在磁场调节板上，此外，另一组第二垫片构件结合到垫片的表面面对间隙空间与物体，以提高间隙空间中的磁场的均匀性。根据本发明的第二方面，其针对的是由于患者躺在MRI仪器中而被放置在MRI仪器中的压迫感的减轻问题，背轭与两个且仅两个柱状磁性和机械连接连接轭，其中心部分的横截面比在上端部和下端部分具有较小的横截面，以确保患者两侧的横向开放性。对于后轭和永磁体也提出了优选的构造。

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