Patent US4594539A successfully refreshed from Google Patents.
US4594539A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light valve
Assignee: MICHELSON ENGINEERING COMPANU Inc
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Filing: 1983-09-06
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Granted: 1986-06-10
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Expires: 2003-09-06
Abstract
Abstract A light valve has a pair of rotating vanes for controlling the cross section of a light beam passing between the vanes. The vanes rotate on corresponding shafts, each controlled by its own integral motor. Separate feedback control systems produce electrical control signals to each motor for rotating each shaft independently of the other to control the desired phase angles of the vanes. In one embodiment, both motors are permanent magnet direct current servo motors in which the wound armature is an integral part of each shaft. A stationary magnetic field generated by permanent magnets is common to both motors. Power is supplied to each armature by a pair of thin, parallel, flexible, electrically conductive strips extending from an end of each shaft. The conductive strips reduce the torque on the shaft when twisted during operation. In one embodiment, the control system produces a calibrated digital control signal from a PROM representing the desired phase angles of the rotating blades. The digital signal is converted to analog control signals compared with position feedback signals from the rotating blades and damping signals produced by blade velocity feedback signals. Error signals fed to variable gain amplifiers control the positions of the vanes. Whenever new commands are input to the variable gain amplifiers, amplifier gain is temporarily switched to a high gain mode, and after the phase angle of the shaft has stabilized, the amplifier gain is switched back to a low gain mode. The separate motors and their servo systems speed up response time and substantially reduce any tendency toward oscillations.
Inventors
- 👤 Gunnar P. Michelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:14
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/005; G03B27/00; G03B27/32
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
218 words
A light valve for varying the size of an opening through which a light beam passes comprising: a pair of spaced apart rotatable shafts, a corresponding vane mounted on each shaft so the vanes extend side by side into the space between the shafts, means for directing light toward the vanes so that rotation of the shafts causes the vanes to move through an angle toward or away from each other for varying the size of the light beam passing between the vanes, a separate servo meter coupled to each shaft for rotating the shafts in unison to adjust the amount of light passing between the vanes, and for each servo motor closed loop servo means responsive to a vane position input signal representing a desired position of each vane for varying the size of the light beam passing between the vanes, and including means for generating a separate position feedback signal as a function of the actual position of the vane on each rotatable shaft throughout operation of the light valve, and means responsive to the vane position input signal and to each position feedback signal for producing separate motor control signals for independently controlling operation of each servo motor to rotate each shaft and vane to constantly pass a selected amount of light between the vanes.
Claim 2
Dependent Claim
218 words
A light valve for varying the size of an opening through which a light beam passes comprising: a pair of spaced apart rotatable shafts, a corresponding vane mounted on each shaft so the vanes extend side by side into the space between the shafts, means for directing light toward the vanes so that rotation of the shafts causes the vanes to move through an angle toward or away from each other for varying the size of the light beam passing between the vanes, a separate servo meter coupled to each shaft for rotating the shafts in unison to adjust the amount of light passing between the vanes, and for each servo motor closed loop servo means responsive to a vane position input signal representing a desired position of each vane for varying the size of the light beam passing between the vanes, and including means for generating a separate position feedback signal as a function of the actual position of the vane on each rotatable shaft throughout operation of the light valve, and means responsive to the vane position input signal and to each position feedback signal for producing separate motor control signals for independently controlling operation of each servo motor to rotate each shaft and vane to constantly pass a selected amount of light between the vanes.
Claim 3
Dependent Claim
44 words
Apparatus according to claim 1 in which each servo motor includes a separate armature winding mounted on each shaft so that each armature rotates with each shaft and in which the closed loop servo means couples the motor control signals to respective armature windings.
Claim 4
Dependent Claim
17 words
Apparatus according to claim 2 in which the motor includes a stationary magnetic field for each armature.
Claim 5
Dependent Claim
52 words
Apparatus according to claim 1 including a separate arm projecting from each shaft and rotatable with the shaft, and separate energy absorbing stops at opposite ends of travel of the arm, the stops being positioned for contact with the arm to limit rotational travel of the shaft in each of two directions.
Claim 6
Dependent Claim
75 words
Apparatus according to claim 4 including a photocell having an output, and an opaque shutter balde carried on each shaft for rotating with the shaft to pass light to the photocell as a function of the angular position of each shaft, the output of the photocell being substantially proportional to the angular position of each shaft for generating the separate position feedback signals representing the actual positions of the vanes during rotation of each shaft.
Claim 7
Dependent Claim
75 words
Apparatus according to claim 1 including a photocell having an output, and an opaque shutter blade carried on each shaft for rotating with the shaft to pass light to the photocell as a function of the angular position of each shaft, the output of the photocell being substantially proportional to the angular position of each shaft for generating the separte position feedback signals representing the actual positions of the vanes during rotation of each shaft.
Claim 8
Dependent Claim
75 words
Apparatus according to claim 1 including thin, flat flexible conductive strips each having one end attached for rotation to the end of a corresponding sahft, with the opposite ends of the strips each being stationay, and in which eact motor includes a separate armature winding affiexed to the shaft corresponding to each motor, the conductive strips providing means for conducting electrical current to the armature windings for coupling the motor control signals to the motors.
Claim 9
Dependent Claim
31 words
Apparatus according to claim 7 including means for allowing one end of the conductive strips to rotate with the shaft while the other end of the conductive strips remains substantially stationary.
Claim 10
Dependent Claim
88 words
Apparatus according to claim 1 in which the closed loop servo means for each servo motor includes means for varying the gain of the motor control signal fed to each motor, means for switching the motor control signal between a high gain mode and a low gain mode, and means for switching from the low gain mode to the high gain mode in response to a change in the vane position input signal representing a desired change in the amount of light to be passed between the vanes.
Claim 11
Dependent Claim
24 words
Apparatus according to claim 1 in which an aramture winding of the motor is mounted to the shaft in close proximity to the vane.
Claim 12
Dependent Claim
21 words
Apparatus according to claim 1 including bearings mounting the shaft for rotation in close proximity to opposite sides of the motor.
Claim 13
Dependent Claim
227 words
A light valve for varying the size of an opening through which a light beam passes: a pair of spaced apart rotatable shafts, a vane carried on each shaft so the vanes extend side by side into the space between the shafts, means for directing light toward the vanes so that rotation of the shafts causes the vanes to move through an angle toward or away from each other for varying the size of the light passing between the vanes, a separate servo motor on each shaft, each servo motor having a separate armature mounted on each shaft, and separate closed loop feedback means responisve to a vane position input signal representing a desired position of each vane for varying the size of the light beam passing between the vanes, and including means for generating a separate vane position feedback signal as a function of the actual position of the vane on each rotatable shaft throughout operation of the light valve, and means responsive to the vane position input signal and to its corresponding vane position feedback signal for producing separate motor control signals fed to the separate aramture windings for independently controlling each servo motor to rotate the shafts in proportion to the motor control signals for rotating the vanes through a phase angle that constantly produces a selected amount of light passing between the vanes.
Claim 14
Dependent Claim
227 words
A light valve for varying the size of an opening through which a light beam passes: a pair of spaced apart rotatable shafts, a vane carried on each shaft so the vanes extend side by side into the space between the shafts, means for directing light toward the vanes so that rotation of the shafts causes the vanes to move through an angle toward or away from each other for varying the size of the light passing between the vanes, a separate servo motor on each shaft, each servo motor having a separate armature mounted on each shaft, and separate closed loop feedback means responisve to a vane position input signal representing a desired position of each vane for varying the size of the light beam passing between the vanes, and including means for generating a separate vane position feedback signal as a function of the actual position of the vane on each rotatable shaft throughout operation of the light valve, and means responsive to the vane position input signal and to its corresponding vane position feedback signal for producing separate motor control signals fed to the separate aramture windings for independently controlling each servo motor to rotate the shafts in proportion to the motor control signals for rotating the vanes through a phase angle that constantly produces a selected amount of light passing between the vanes.
Claim 15
Dependent Claim
17 words
Apparatus according to claim 12 in which the closed loop feedback means is a second order servo.
Claim 16
Dependent Claim
18 words
Apparatus according to claim 12 including a stationary magnetic field gnerated by permanent magnet means surrounding each armature.
Claim 17
Dependent Claim
55 words
Apparatus according to claim 12 including a separate elongated, thin, flexible electrically conductive strip coupled to the armature winding of each servo motor, one end of each conductive strip being rotatable with rotation of each shaft for supplying electrical input signals to the armature, and means for holding apparatus ends of the conductive strips stationary.
Claim 18
Dependent Claim
84 words
Apparatus according to claim 12 in which each closed loop servo means includes means for varying the gain of the motor control signal fed to each motor, means for switching the motor control signal between a high gain mode and a low gain mode, and means for switching from the low gain mode to the high gain mode in response to a change in the vane position input signal representing a desired change in the amount of light to be passed between the vanes.
Claim 19
Dependent Claim
37 words
Apparatus according to claim 12 including means for mounting each shaft for rotation independently of the other shaft so that each servo motor and its corresponding closed loop servo means independently controls angular rotation of each shaft.
Claim 20
Dependent Claim
84 words
Apparatus according to claim 17 in which each closed loop servo means includes means for varying the gain of the motor control signal fed to each motor, means for switching the motor control signal between a high gain mode and a low gain mode, and means for switching form the low gain mode to the high gain mode in response to a change in the vane position input signal representing a desired change in the amount of light to be passed between the vanes.
Claim 21
Dependent Claim
40 words
Apparatus according to claim 18 including an elongated, thin, flexible electrically conductive strip coupled to the armature winding of each servo motor, the conductive strips being rotatable with rotation of each shaft for supplying electrical input signals to the armature.
Claim 22
Dependent Claim
17 words
Apparatus according to claim 19 in which the closed loop feedback means is a second order servo.
Claim 23
Dependent Claim
18 words
Apparatus according to claim 20 including a stationary magnetic field generated by permanent magnet ans surrounding each armature.
Claim 24
Dependent Claim
186 words
A light valve for varying the size of an opening through which a light beam passes comprising: a pair of rotatable shafts, a corresponding vane on each shaft, means for directing light toward the vanes so that rotation of the vanes can pass a selected amount of light between the vanes, a separate servo motor coupled to each shaft for rotating the shafts in unison to adjust the amount of light passing between the vanes, and for each servo motor closed loop servo means for controlling operation of the motor to rotate its corresponding shaft to constantly pass a selected amount of the light between the vanes, in which each closed loop servo means generates (1) a position feedback signal dependent upon the instantaneous phase angle of rotation of the vane, and (2) a velocity feedback signal dependent upon the rate at which the shaft is rotating; and including means for summing the position feedback signal and the velocity feedback signal along with an input command representing the desired amount of light to pass between the vanes to produce an error signal for controlling the motor.
Claim 25
Dependent Claim
186 words
A light valve for varying the size of an opening through which a light beam passes comprising: a pair of rotatable shafts, a corresponding vane on each shaft, means for directing light toward the vanes so that rotation of the vanes can pass a selected amount of light between the vanes, a separate servo motor coupled to each shaft for rotating the shafts in unison to adjust the amount of light passing between the vanes, and for each servo motor closed loop servo means for controlling operation of the motor to rotate its corresponding shaft to constantly pass a selected amount of the light between the vanes, in which each closed loop servo means generates (1) a position feedback signal dependent upon the instantaneous phase angle of rotation of the vane, and (2) a velocity feedback signal dependent upon the rate at which the shaft is rotating; and including means for summing the position feedback signal and the velocity feedback signal along with an input command representing the desired amount of light to pass between the vanes to produce an error signal for controlling the motor.
Claim 26
Dependent Claim
81 words
Apparatus according to claim 22 in which each closed loop servo means includes means for varying the gain of a control signal fed to the motor, means for switching the control signal between a high gain mode and a low gain mode, and means for switching form the low gain mode to the high gain mode in response to a change in an input command signal representing a desired change in the amount of light to be passed between the vanes.
Claim 27
Dependent Claim
35 words
Apparatus according to claim 22 in which each servo motor includes a separate armature winding mounted on each shaft, and in which the closed loop servo means provides electrical control signals to each armature winding.
Claim 28
Dependent Claim
77 words
Apparatus according to claim 24 in which the feedback means includes a photocell having an output, and an opaque shutter blade carried on each shaft for rotating with the shaft to pass light to the photocell in proportion to the angular position of the shaft, the output of the photocell being a function of the angular position of the shaft; the shutter balde, armature and the vane all being rigidly affixed to each shaft to reduce vibrations.
Claim 29
Dependent Claim
180 words
A light valve for varying the size of an opening through which a light beam passes comrpising: a pair of spaced apart rotatable shafts, a corresponding vane mounted on each shaft so the vanes extend side by side into the space between the shafts, means for directing light toward the vanes so that rotation of the vanes causes the vanes to move through an angle toward or away from each other for varying the size of the light beam passing between the vanes, a separate servo motor coupled to each shaft for rotating the shafts in unison to adjust the amount of light passing between the vanes, and closed loop servo means responsive to a common external input command representing a desired amount of light to pass between the vanes, the servo means comprising separate, independent second order closed loop servo systems each responsive to the common input command for producing separate motor control signals for independently controlling operation of each motor to constantly rotate the vanes in unison to apss a selected amount of the light between the vanes.
Claim 30
Dependent Claim
180 words
A light valve for varying the size of an opening through which a light beam passes comrpising: a pair of spaced apart rotatable shafts, a corresponding vane mounted on each shaft so the vanes extend side by side into the space between the shafts, means for directing light toward the vanes so that rotation of the vanes causes the vanes to move through an angle toward or away from each other for varying the size of the light beam passing between the vanes, a separate servo motor coupled to each shaft for rotating the shafts in unison to adjust the amount of light passing between the vanes, and closed loop servo means responsive to a common external input command representing a desired amount of light to pass between the vanes, the servo means comprising separate, independent second order closed loop servo systems each responsive to the common input command for producing separate motor control signals for independently controlling operation of each motor to constantly rotate the vanes in unison to apss a selected amount of the light between the vanes.
Claim 31
Dependent Claim
33 words
Apparatus according to claim 26 in which each servo motor includes a separate armature winding mounted on each shaft, the closed loop servo means coupled said motor control signals to each armature winding.
Claim 32
Dependent Claim
56 words
Apparatus according to claim 27 including a photocell having an output, and an opaque shutter blade carried on each shaft for rotating with the shaft to pass amount of light to the photocell dependent upon the angular position of the shaft, the output of the photocell being substantially proportional to the angular position of the shaft.
Claim 33
Dependent Claim
30 words
Apparatus according to claim 28 in which the vane armature and shutter blade are all rigidly affixed to the common shaft for forming a single rigid unit to reduce vibrations.
Claim 34
Dependent Claim
82 words
Apparatus according to claim 26 in which each closed loop servo means includes means for varying the gain of the control signal fed to the motor, means for switching the motor control signal between a high gain mode and a low gain mode, and means for switching form the low gain mode to the high gain mode in response to a change in the input command signal representing a desired change in the amount of light to be passed between the vanes.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-09 | 1989-12-09 | 1990-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-09 | 1993-12-09 | 1994-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-09 | 1997-12-09 | 1998-06-10 | $7700.00 | Window Closed / Lapsed |