Orientation detector arrangement

An orientation detector arrangement is adapted to detect the orientation of a first component relative to a second component, preferably during endoscopic surgery. The first component is a transmitter which may be worn on a surgeon's head. The transmitter is adapted to transmit a plurality of unique identifiable signals along mutually diverging beams. The second component is a detector which is adapted to distinguish between the individual signals transmitted by the transmitter. The detector is connected by a control circuit to an endoscopic camera which is, in turn, connected to provide an image on a display screen. The detector and the associated control circuit are able to control movement of the endoscopic camera in response to movement of the surgeon's head.

TECHNICAL FIELD
 THE PRESENT INVENTION relates to an orientation detector, arrangement, and
 in particular relates to an orientation detector arrangement adapted to
 detect the orientation of one component relative to another component.
 The invention will be described with reference to a specific embodiment,
 which has been devised for use where a particular need exists, but the
 invention may find other applications.
 BACKGROUND ART
 In certain surgical situations, for example in endoscopic surgery, the
 surgeon requires to use both hands simultaneously to manipulate various
 instruments, but also requires to control the position of the endoscopic
 camera. The present invention seeks to provide an arrangement that may be
 used by a surgeon to control an item such as a camera without moving his
 hands or feet.
 WO96/35960 discloses a complex system for determining the position and
 orientation of a movable object in space relative to a stationary object
 in which two transmitter units are mounted in a fixed spaced relationship
 on a stationary consul, and two receiver units are mounted on the movable
 object which may, for example, be a head-set. Each transmitter unit has a
 triplet of orthogonally arranged light-emitting diodes, each of which
 generates a hemispherical beam of radiation. The beams of radiation
 substantially overlap. Each receiver unit has six photo-detectors, each of
 which has a plane of sensitivity such that the intensity of incidence
 radiation is proportional to the co-sign of the angle of incidence of the
 radiation. The six photo-detectors are arranged so that they form four
 sets of three photo-detectors with the photo-detectors in each set having
 their planes of sensitivity arranged orthogonally. Each of the
 photo-detectors generates a direction co-sign signal proportional to the
 intensity of radiation received from each LED.
 The described arrangement is relatively complex, and relies on each
 photo-detector receiving light from a substantial number of the
 light-emitting diodes. The arrangement does generate a control signal,
 which depends upon the ratio of the intensities of the radiation received
 by each photo-detector from each light-emitting diode.
 GB 2,284,957A discloses an optical system for the remote tracking of the
 position and/or orientation of an object such as the helmet of a pilot.
 The Specification teaches that two groups of light-emitting diodes are
 provided on the helmet, and light from the light-emitting diodes are
 imaged on to photo-sensitive layers of two position sensitive detectors.
 An output signal is provided from each layer which depends upon the
 position of the spots of light imaged on to the layer from the
 light-emitting diodes. The output signals is used to track movement of the
 helmet of the pilot.
 SUMMARY OF THE INVENTION
 According to this invention there is provided an orientation detector
 arrangement, adapted to detect the orientation of a first component
 relative to a second component, wherein the first component comprises
 transmitter means adapted to transmit a plurality of diverging beams, each
 beam being uniquely identifiable, the second component comprising a
 detector, the detector being adapted to detect and distinguish the beams
 transmitted by the transmitters, the detector being associated with a
 control circuit adapted to generate a control signal in dependence upon
 the identity of a beam or beams detected by the detector.
 Conveniently each beam is a beam of light in or near the visible spectrum.
 Advantageously each beam is a beam of infra-red light.
 In one embodiment each beam is pulse-code modulated in a unique way. In a
 preferred embodiment each beam carries a signal generated by an
 oscillator, which oscillates at a unique respective frequency.
 Conveniently the means to distinguish the beams is a plurality of tuned
 circuits, each tuned circuit being tuned to a frequency of a respective
 one of the oscillators.
 Preferably the first component is provided with means to enable the first
 component to be worn on the head of a person.
 Advantageously the first component comprises a housing provided with a
 head-band or strap.
 Conveniently the detector is provided on or adjacent a visual display.
 Advantageously the control circuit is adapted to control the operation of
 a component which causes the image on the visual display unit or monitor
 to alter.
 Preferably the control circuit controls a camera, the image from the camera
 being displayed on the visual display unit or monitor.
 Alternatively the control circuit controls a component which is visible in
 the image as shown on the visual display unit or monitor, or which, when
 controlled, causes said image to change.
 According to another aspect of this invention there is provided a control
 apparatus comprising a first component adapted to be worn on the head of
 an operator, the first component having means which emit a plurality of
 diverging beams, each beam being uniquely identifiable, and detector means
 to determine the orientation of the first component and control means to
 generate a control signal in accordance with the orientation of the first
 component, the detector means being adapted to detect and identify the
 beam or beams being received, the detector means being associated with the
 control means which are adapted to generate a control signal in dependence
 upon the identity of the beam or beams detected, wherein the control means
 control movement or function of a further device.
 Advantageously the further device is a camera, the detector means being
 located on or adjacent a visual display unit or monitor adapted to display
 an image of the scene viewed by the camera.
 Alternatively the means are located on or adjacent a visual display unit or
 monitor adapted to display an image of a scene viewed by a camera, the
 further device comprising a component which is visible within that scene.

DETAILED DESCRIPTION OF THE INVENTION
 Referring initially to FIG. 1 of the drawings, a first component comprises
 a transmitter assembly which includes a housing 1 associated with a band
 or strap 2, which is provided to enable the housing 1 to be secured to the
 head of a person, such as a surgeon. It is to be appreciated that the
 housing may be provided with any appropriate means to retain the housing
 in position and may be incorporated into an appropriate surgeon's hat.
 The front face 3 of the housing is provided with a plurality of
 transmitters. In the embodiment illustrated four transmitters 5, 6, 7, 8
 are provided. The transmitters are adapted to transmit signals, the
 signals being directed along mutually diverging beams. In the embodiment
 illustrated, the beams 5', 7' from the transmitters 5 and 7 are located on
 a substantially horizontal plane but are directed to diverge away from a
 center line which extends perpendicularly from the housing 1. Similarly,
 the beams 6', 8' from the transmitters 6 and 8, diverge downwardly and
 upwardly, respectively, from the center line. The four beams illustrated
 thus mutually diverge away from each other. The divergence of the beams
 has been substantially exaggerated in the drawings in order to facilitate
 an understanding of the invention. In a practical embodiment the beams
 would be much closer to being parallel than as presently illustrated.
 Although, in the presently described embodiment of the invention, four
 transmitters are provided, it is to be appreciated that any appropriate
 number of transmitters may be provided to generate the diverging beams.
 Each beam 5', 6', 7', 8' will be of generally conical form.
 Although the transmitters may transmit radiation of an appropriate
 frequency it is considered that the optimum form of transmitter comprises
 a transmitter which transmits light in or near the visible spectrum. The
 transmitters may comprise light-emitting diodes or lamps, and preferably
 emit infra-red light.
 Each transmitter will be associated with appropriate means to form the
 respective conical beams discussed above. Thus, each transmitter may be
 associated with one or more lenses, or one or more shutters or irises.
 The signal transmitted by each transmitter is different from the signal
 transmitted by the other transmitters. Thus, for example, each transmitter
 may transmit light of a different color or wavelength. Alternatively, each
 transmitter may transmit light which is pulse-coded in a unique manner. It
 is preferred, however, that each transmitter is driven by an oscillator of
 a different frequency. Thus, each beam carries a frequency which is unique
 to that beam.
 It is to be appreciated, therefore, that the illustrated transmitter
 transmits four diverging beams, each of which is uniquely identifiable.
 FIG. 2 illustrates a visual display unit or monitor 9 provided with a
 detector 10 located adjacent the screen 11 of the visual display unit or
 monitor.
 The detector 10 is adapted to detect the signal generated by the
 transmitters.
 The detector may be an appropriate photo-sensor which is connected to means
 adapted to distinguish the signals transmitted from the transmitters. The
 distinguishing means may comprise filters responsive to the frequencies of
 the different colors of light transmitted, if this expedient is used, or
 digital means adapted to distinguish signals with different pulse-codings,
 if this distinguishing means is used. However, in the preferred
 embodiment, where the transmitters are driven by oscillators of different
 frequencies, the detector is associated with four tuned circuits 12, 13,
 14, 15, which may comprise phase-locked loops, each tuned circuit being
 tuned to a respective one of the transmitter frequencies.
 In the embodiment illustrated, the tuned circuits are connected to a
 control circuit 16 which is adapted to control an endoscopic camera 17.
 The endoscopic camera 17 is connected to provide an image on the screen
 11.
 It is to be understood that a surgeon using the arrangement described and
 illustrated will wear the housing 1 on his head in such a position that
 when the surgeon is looking directly at the screen 11 of the visual
 display unit or monitor 9, the center line between the diverging beams is
 aligned with the detector 10. Because the beans diverge, the detector 10
 will not receive any signal from any one of the transmitters 5, 6, 7 or 8.
 Should the surgeon move his head, for example, towards the left, the beam
 5' from the transmitter 5 will begin to impinge on the detector 10. The
 appropriate tuned circuit will generate an output which is fed to the
 control circuit 16. The control circuit 16 will be adapted to move the
 endoscopic camera to the left. Thus, by moving his head to the left, the
 surgeon will be able to control the movement of the camera, so that the
 camera moves to the left.
 It is to be appreciated that should the surgeon move his head towards the
 right, the beam 7' from the transmitter 7 will be detected by the detector
 10 and the appropriate tuned circuit will provide an output to the control
 circuit 16 causing the endoscopic camera to move to the right. A
 corresponding effect is experienced if the surgeon should move his head up
 or down.
 If the beams 5', 6', 7', 8' have an appropriate divergence, where the beams
 reach the detector 10, the beams may, in certain regions, overlap.
 In such a situation, should the surgeon move his head so as to observe, for
 example, the top left-hand corner of the screen, the detector 10 will
 detect a signal from the transmitter 5 and also from the transmitter 6.
 The camera 17 may thus be controlled to move leftwardly and upwardly.
 It is thus to be appreciated that by moving his head appropriately, the
 surgeon may provide eight possible control signals to effect movement of
 the endoscopic camera.
 Although the invention has been described, by way of example, as
 controlling an endoscopic camera, it is to be appreciated that an
 arrangement similar to that illustrated in FIGS. 1 and 2 may be utilized
 to control other items, such as a manipulator or a robotic device provided
 to assist a surgeon. The manipulator may manipulate an item that is
 visible in the image displayed on the visual display unit or monitor 9.
 Whilst the invention has been described, by way of example, with reference
 to an apparatus intended for use by a surgeon, it is to be appreciated
 that the embodiments of the invention may find many other uses, especially
 where people have to perform complicated functions that require the use of
 both hands and where further control functions need to be carried out. It
 is envisaged that the invention may find other uses.
 Although, in the described embodiment of the invention, the housing
 containing the transmitters is moved relative to the detector, it is to be
 appreciated that in alternative embodiments of the invention, the detector
 may move relative to the housing containing the transmitters. As the
 detector moves from an initial position in which it is aligned with the
 center line, the detector will receive the signal transmitted by one or
 more of the transmitters. An appropriate control function can then be
 performed, Such an embodiment is, of course, still relying on the fact
 that the orientation of the transmitter housing relative to the receiver
 is being detected.