Mirror-ring assembly for bi-directional optical communication between a rotor and a stator

Patent metadata

Field	Value
Publication number	US-10326561-B2
Application number	US-201514748951-A
Country	US
Kind code	B2
Filing date	Jun 24, 2015
Priority date	Jun 24, 2015
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

An optical rotary joint communication apparatus for communicating between a rotor and a stator. Optical sources and detectors are arranged on both the rotor and the stator to provide bi-directional communication. As the rotor rotates, downlink detectors on the rotor sequentially communicate via line-of-sight optical channels with corresponding downlink receivers on the stator. Each downlink receiver is provided a curved mirror reflecting the downlink beam onto the downlink receiver when the rotation angle of the rotor is within a corresponding angle interval. When the rotation angle moves past the angle interval, the downlink beams transition to another mirror and another downlink receiver. The downlink beams are directed predominantly tangential to the rotor circumference. Adjacent downlink transmitters transmit redundant data, and transitions between downlink receivers are staggered for adjacent downlink transmitters to occur at non-overlapping rotation angles in order to prevent loss of data during transitions.

First claim

The invention claimed is:

1. A mirror-ring apparatus, comprising:
a stator;
a rotor configured to rotate relative to the stator;
a first downlink optical source arranged on the rotor and configured to provide a downlink beam radiating at a predefined downlink angle with respect to the rotor that is predominantly orthogonal to a radial direction from a center of rotation of the rotor, wherein the first downlink optical source encodes data packets on the downlink beam of the first downlink optical source;
a second downlink optical source arranged on the rotor and configured to provide a second downlink beam radiating at a predefined second downlink angle with respect to the rotor that is predominantly orthogonal to the radial direction;
a plurality of downlink receivers arranged on the stator and configured to receive light from the first downlink optical source and decode the data packets; and
a plurality of stator mirrors arranged on the stator, wherein
throughout each angle interval of a first plurality of angle intervals of a rotation angle of the rotor, a respective stator mirror of the plurality of stator mirrors is configured to reflect the downlink beam from the first downlink optical source to a corresponding receiver of the plurality of downlink receivers, and, throughout respective gaps between adjacent angle intervals of the first plurality of angle intervals, the downlink beam from the first downlink optical source is not reflected from any of the plurality of stator mirrors to any of the plurality of downlink optical receivers,
throughout each angle interval of a second plurality of angle intervals of the rotation angle of the rotor, the second downlink beam reflects from a respective mirror of the plurality of stator mirrors to a corresponding receiver of the plurality of downlink optical receivers, and each gap between adjacent angle intervals of the first plurality of angle intervals is spanned by a respective angle interval of the second plurality of angle intervals.

2. The mirror-ring apparatus according to claim 1 , further comprising:
a plurality of uplink optical sources connected to the stator, wherein each optical source is configured to transmit an uplink beam directed at an angle predominantly orthogonal to the radial direction; and
a first uplink optical detector arranged on the rotor and configured to receive the uplink optical beam of the corresponding uplink optical source when the rotation angle of the rotor is within the corresponding angle interval of the first plurality of angle intervals.

3. The mirror-ring apparatus according to claim 2 , further comprising:
a second uplink optical detector arranged on the rotor and configured to receive the uplink optical beam of the uplink optical source that corresponds to the rotation angle of the rotor, when the rotation angle of the rotor is within the corresponding angle interval of the second plurality of angle intervals.

4. The mirror-ring apparatus according to claim 2 , wherein
the first uplink optical detector is arranged on the rotor adjacent to the first downlink optical source; and
each uplink optical source of the plurality of uplink optical sources is arranged on the stator adjacent to the corresponding downlink receiver of the plurality of downlink receivers.

5. The mirror-ring apparatus according to claim 2 , wherein the uplink optical beam is a fan beam that is narrow in the direction orthogonal to a plane of rotation of the rotor and fans out in the plane of rotation of the rotor.

6. The mirror-ring apparatus according to claim 1 , wherein
each of the first plurality of angle intervals represents the rotation angles of the rotor for which the downlink beam of the first downlink optical source is reflected from a respective stator mirror of the plurality of stator mirrors and is received at a corresponding one of the plurality of downlink receivers, and a gap between adjacent angle intervals of the first plurality of angle intervals represents a transition of the downlink beam between adjacent stator mirrors; and
each of the second plurality of angle intervals represents of the rotation angles of the rotor for which the downlink beam of the second downlink optical source is reflected from a respective stator mirror of the plurality of stator mirrors and is received at a corresponding one of the plurality of downlink receivers, and a gap between adjacent angle intervals of the second plurality of angle intervals represents a transition of the downlink beam between adjacent stator mirrors.

7. The mirror-ring apparatus according to claim 1 , wherein the first downlink optical source is configured to transmit data equivalent to data transmitted by the second downlink optical source.

8. The mirror-ring apparatus according to claim 1 , wherein
the first downlink optical source is configured to communicate data from the rotor to the stator by partitioning the data into the data packets, wherein
the data packets are each concatenated with a header including reassembly information, and error-correction data.

9. The mirror-ring apparatus according to claim 8 , further comprising:
a rotary encoder configured to measure a rotor angle representing the rotation angle of the rotor, wherein
when the rotor angle measured by the rotary encoder indicates that the downlink beam of the first downlink optical source is transitioning between adjacent stator mirrors, the data packets are not communicated using the downlink beam of the first downlink optical source.

10. The mirror-ring apparatus according to claim 9 , further comprising:
a non-transitory computer-readable memory configured to store the data packets, wherein the non-transitory computer readable memory buffers the data packets when the first downlink optical source is transitioning between adjacent stator mirrors.

11. The mirror-ring apparatus according to claim 8 , wherein
the second downlink optical source communicates the data packets from the rotor to the stator when the first downlink optical source is transitioning between adjacent stator mirrors.

12. The mirror-ring apparatus according to claim 1 , wherein a number of the plurality of stator mirrors is greater than four.

13. A computed tomography (CT) apparatus, comprising:
a stator;
a rotor configured to rotate relative to the stator;
a radiation source radiating radiation into an object space and configured to rotate with the rotor;
a plurality of detector elements configured to detect the radiation transmitted from the radiation source through the object space, wherein the plurality of detector elements are configured to generate projection data;
processing circuitry configured to partition the projection data into data packets;
a first downlink optical source arranged on the rotor and configured to provide a downlink beam radiating at a predefined downlink angle with respect to the rotor that is predominantly orthogonal to a radial direction from a center of rotation of the rotor, wherein the first downlink optical source encodes the data packets on the downlink beam of the first downlink optical source;
a second downlink optical source arranged on the rotor and configured to provide a second downlink beam radiating at a predefined second downlink angle with respect to the rotor that is predominantly orthogonal to the radial direction rotor, wherein the second downlink optical source encodes the data packets on the downlink beam of the second downlink optical source;
a plurality of downlink receivers arranged on the stator and configured to receive the downlink beam from the first downlink optical source and decode the data packets; and

Assignees

• Toshiba Medical Sys Corp

Inventors

• Dudek Marek
• Ivanov Ognian

Classifications

• H04L1/004

  by using forward error control (H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00) · CPC title

• H04L1/1809

  Selective-repeat protocols · CPC title

• H02K11/20

  for measuring, monitoring, testing, protecting or switching (rectifiers H02K11/04; power electronics H02K11/33) · CPC title

• H04B10/11

  Arrangements specific to free-space transmission, i.e. transmission through air or vacuum · CPC title

• H02K1/12

  Stationary parts of the magnetic circuit · CPC title