Patent EP0520388A2 successfully refreshed from Google Patents.
EP0520388A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Magnetic position sensor
Assignee: Eastman Kodak Co
•
Filing: 1992-06-24
•
Granted: —
•
Expires: 2012-06-24
Abstract
Abstract A beam scanning galvanometer (44) is disclosed which oscillates a mirror (60) in a non-resonant mode. The moving parts of the galvanometer are made with as small a moment of inertia as possible because the mirror is oscillated in a non-resonant mode. The galvanometer uses two sets of crossed leaf-springs (70) to support the mirror instead of bearings which are usually used in non-resonant galvanometers. Each of the sets of leaf-springs is formed of a single strip of cold rolled stainless steel. The springs are embedded in uniquely shaped cavities in a permanent magnet (62) that supports the mirror at a distance very close to an axis of rotation of the mirror. The mirror is specially shaped with beveled edges so that its moment of inertia is low and so that it can oscillate in very close proximity to a driving current coil (64) which surrounds the mirror supporting magnet. A magnetic position sensor (90) is used to detect an angular position of the mirror during operation of the galvanometer. A compensating system eliminates distorting magnetic field effects from a magnetic driving system from adversely influencing the magnetic position sensor. Signals from the magnetic position sensor are usable to provide accurate feedback information to a galvanometer driving system.
Inventors
- 👤 David Mark c/o EASTMAN KODAK COMPANY Orlicki
- 👤 Bruce Edward c/o EASTMAN KODAK COMPANY Koppe
- 👤 John Michael c/o EASTMAN KODAK COMPANY Kresock
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 21:21
CPC Classifications
G; G01; G01R; G01R5/00; G01R5/14; G01R5/16; G02; G02B; G02B26/00; G02B26/08; G02B26/10
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
70 words
Apparatus for sensing a position of a movable object driven by a magnetic field comprising: a magnet coupled to the object and adapted to move therewith; a magnetic sensor for sensing the position of the magnet relative to the sensor; and means for canceling an effect generated on the sensor by magnetic fields, other than those effects which are indicative of a relative position of the object to the sensor.
Claim 2
Dependent Claim
76 words
The apparatus of claim 1 wherein the magnetic field for driving the object is produced by a driving current passing through a driving coil and the apparatus further comprises: means for producing a compensating current that is opposite in polarity from the driving current; and means for producing a magnetic field near the sensor with the compensating current so as to cancel the effect of the magnetic field produced by the driving current on the sensor.
Claim 3
Dependent Claim
110 words
The apparatus of claim 1 wherein the magnetic field for driving the object is produced by a means for producing a driving current passing through a driving coil and the apparatus further comprises: means for producing a compensating signal which is proportional to the driving current; means for combining the compensating signal with an uncompensated signal produced by the sensor to produce a combined signal, said combined signal being indicative of the position of the object; and means for supplying the combined signal to the means for producing a driving current so that said producing means provides a sufficient amount of current to produce a desired position of the object.
Claim 4
Dependent Claim
80 words
Apparatus for sensing a position of a movable object driven by a pulsating magnetic field that produces pulses of position correcting force comprising: a magnet coupled to the object and adapted to move therewith; a magnetic sensor for sensing the position of the magnet relative to the sensor; and means for canceling an effect generated on the sensor by the pulsating magnetic fields, other than those effects which are indicative of a relative position of the object to the sensor.
Claim 5
Dependent Claim
85 words
The apparatus of claim 4 wherein the magnetic field for driving the object is produced by a driving current pulses passing through a driving coil at a frequency higher than about 300 Hz and the apparatus further comprises: means for producing a compensating current that is opposite in polarity from the driving current; and means for producing a magnetic field near the sensor with the compensating current so as to cancel the effect of the magnetic field produced by the driving current on the sensor.
Claim 6
Dependent Claim
118 words
The apparatus of claim 4 wherein the magnetic field for driving the object is produced by a means for producing a driving current passing through a driving coil at a frequency higher than about 300 Hz and the apparatus further comprises: means for producing a compensating signal which is proportional to the driving current; means for combining the compensating signal with an uncompensated signal produced by the sensor to produce a combined signal, said combined signal being indicative of the position of the object; and means for supplying the combined signal to the means for producing a driving current so that said producing means provides a sufficient amount of current to produce a desired position of the object.
Claim 7
Dependent Claim
73 words
A beam scanning galvanometer comprising: a mirror adapted to rotate about an axis of rotation; a magnet coupled to the mirror and adapted to rotate therewith; a sensor for sensing the angular position of the magnet relative to the axis of rotation; and means for canceling an effect of magnetic fields generated in the beam scanning galvanometer, on the sensor, other than those effects which are indicative of angular position of the mirror.
Claim 8
Dependent Claim
69 words
The beam scanning galvanometer of claim 7 further comprising: a driving coil; means for producing a driving current in the driving coil; means for producing a compensating current that is opposite in polarity from the driving current; and means for producing a magnetic field near the sensor with the compensating current so as to cancel the effect of the magnetic field produced by the driving current on the sensor.
Claim 9
Dependent Claim
102 words
The beam scanning galvanometer of claim 7 further comprising: a driving coil; means for producing a driving current in the driving coil; means for producing a compensating signal which is proportional to the driving current; means for combining the compensating signal with an uncompensated signal produced by the position sensor to produce a combined signal, said combined signal being indicative of the angular position of the mirror; and means for supplying the combined signal to the means for producing a driving current so that said producing means provides a sufficient amount of current to produce a desired angular position of the mirror.
Claim 10
Dependent Claim
15 words
The beam scanning galvanometer of claim 7 wherein the sensor is a Hall effect sensor.
Claim 11
Dependent Claim
26 words
The beam scanning galvanometer of claim 7 wherein the magnet is positioned from the sensor a distance within a range of about 0.010 to 0.050 inches.
Claim 12
Dependent Claim
107 words
The beam scanning galvanometer of claim 9 wherein the means for producing a compensating signal comprises: a resistor coupled in series with the driving coil; an amplifier being adapted to amplify a voltage drop across the resistor with a gain given by the expression K = - H(Fi/i) , where H is a gain of the sensor, Fi is the flux of the magnetic field produced by the current in the driving coil and i is the current passing through the resistor; and an adder with inputs coupled to the amplifier and the sensor and with an output coupled to the means for producing the driving current.
Claim 13
Dependent Claim
76 words
A beam scanning galvanometer comprising: a mirror coupled to a driving magnet and adapted to rotate about an axis of rotation; a sensor magnet coupled to the mirror and adapted to rotate therewith; a sensor for sensing the angular position of the sensor magnet relative to the axis of rotation; and means for canceling the effect of magnetic fields generated in the beam scanning galvanometer on the sensor, other than the effects of the sensor magnet.
Claim 14
Dependent Claim
71 words
The beam scanning galvanometer of claim 13 further comprising: a driving coil; means for producing a driving current in the driving coil; means for producing a compensating current that is opposite in polarity from the driving current; means for producing a magnetic field in the vicinity of the sensor with the compensating current so as to cancel the effect of the magnetic field produced by the driving current on the sensor.
Claim 15
Dependent Claim
90 words
The beam scanning galvanometer of claim 13 further comprising: a driving coil; means for producing a driving current in the driving coil; means for producing a compensating signal which is proportional to the driving current; means for adding the compensating signal to an uncompensated signal produced by the position sensor to produce a combined signal; and means for supplying the combined signal to the means for producing a driving current so that said producing means produces a sufficient amount of current to provide a desired angular position of the mirror.
Claim 16
Dependent Claim
15 words
The beam scanning galvanometer of claim 13 wherein the sensor is a Hall effect sensor.
Claim 17
Dependent Claim
26 words
The beam scanning galvanometer of claim 13 wherein the magnet is positioned from the sensor a distance within a range of about 0.010 to 0.050 inches.
Claim 18
Dependent Claim
40 words
The beam scanning galvanometer of claim 14 wherein the means for producing a compensating magnetic field near the sensor comprises a compensating coil positioned near the sensor, the compensating coil being adapted to permit the compensating current to pass therethrough.
Claim 19
Dependent Claim
67 words
The beam scanning galvanometer of claim 18 wherein the compensating coil is formed around a member having high magnetic permeability and adapted to be moved longitudinally along an axis of the coil so as to produce desired adjustment of the magnitude of the magnetic field which the compensating coil produces and thus enable a precise cancellation of undesired effects of magnetic fields acting on the position sensor.
Claim 20
Dependent Claim
91 words
A beam scanning galvanometer comprising: a mirror adapted to oscillate about an axis of rotation, the mirror being supported in a manner which produces a resonant frequency at which the mirror can oscillate; a magnet coupled to the mirror and adapted to rotate therewith; a sensor for sensing the angular position of the magnet relative to the axis of rotation; and means for canceling an effect of magnetic fields generated in the beam scanning galvanometer on the sensor, other than those effects which are indicative of angular position of the mirror.
Claim 21
Dependent Claim
94 words
The beam scanning galvanometer of claim 20 further comprising: a driving coil; means for producing a driving current in the driving coil in a series of varying pulses with each pulse being produced at a frequency that exceeds the resonant frequency at which the mirror can oscillate; means for producing a compensating current that is opposite in polarity from the driving current; and means for producing a magnetic field near the sensor with the compensating current so as to cancel the effect of the magnetic field produced by the driving current on the sensor.
Claim 22
Dependent Claim
127 words
The beam scanning galvanometer of claim 20 further comprising: a driving coil; means for producing a driving current in the driving coil in a series of varying pulses with each pulse being produced at a frequency that exceeds the resonant frequency at which the mirror can oscillate; means for producing a compensating signal which is proportional to the driving current; means for combining the compensating signal with an uncompensated signal produced by the position sensor to produce a combined signal, said combined signal being indicative of the angular position of the mirror; and means for supplying the combined signal to the means for producing a driving current so that said producing means provides a sufficient amount of current to produce a desired angular position of the mirror.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.