Light valve shutter control system with zero-light position control

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,
• in which light is directed 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 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 a closed loop servo system 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, in which a separate position feedback signal is generated 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, in which:
• (1) the vanes are aligned on a common plane, (2) the vanes rotate in unison about parallel axes in opposite rotational directions on the same side of the plane to reduce or enlarge the amount of light transmission, (3) the width of the vanes is designed to produce a slight overlap along their confronting outer edges when the vanes are rotated to a closed light-blocking position aligned with the common plane, and (4) a time delay is produced between the vanes when moving the vanes to the closed position to prevent jamming of the vanes when moving toward the closed position.

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 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, a closed loop servo system 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 in which a separate position feedback signal is generated as a function of the actual position of the vane on each rotatable shaft throughout operation of the light valve, and a controller 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;
• in which:
• (1) the vanes are aligned on a common plane, (2) the vanes both rotate about parallel axes in the same rotational direction away from opposite sides of the plane to enlarge the light opening between the vanes, (3) the vanes both rotate in the same rotational direction toward the plane to reduce the light opening between the vanes, and (4) the relative lengths of the vanes are such that they produce a slight overlap along their confronting outer edges when rotating to the closed position on the common plane, to prevent jamming of the vanes as they move to the closed position;
• or (1) the vanes are aligned on a common plane, (2) the vanes rotate in unison about parallel axes in opposite rotational directions on the same side of the plane to reduce or enlarge the amount of light transmission, (3) the width of the vanes is designed to produce a slight overlap along their confronting outer edges when the vanes are rotated to a closed light-blocking position aligned with the common plane, and (4) a time delay is produced between the vanes when moving the vanes to the closed position to prevent jamming of the vanes when moving toward the closed position.

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,
• in which light is directed 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 a closed loop servo system 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 in which the position feedback signal and the velocity feedback signal are summed 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;
• and in which:
• (1) the vanes are aligned on a common plane, (2) the vanes both rotate about parallel axes in the same rotational direction away from opposite sides of the plane to enlarge the light opening between the vanes, (3) the vanes both rotate in the same rotational direction toward the plane to reduce the light opening between the vanes, and (4) the relative lengths of the vanes are such that they produce a slight overlap along their confronting outer edges when rotating to the closed position on the common plane, to prevent jamming of the vanes as they move to the closed position;
• or
• (1) the vanes are aligned on a common plane, (2) the vanes rotate in unison about parallel axes in opposite rotational directions on the same side of the plane to reduce or enlarge the amount of light transmission, (3) the width of the vanes is designed to produce a slight overlap along their confronting outer edges when the vanes are rotated to a closed light-blocking position aligned with the common plane, and (4) a time delay is produced between the vanes when moving the vanes to the closed position to prevent jamming of the vanes when moving toward the closed position.

A light valve for varying the size of an opening a corresponding vane mounted on each shaft so that 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,
• in which light is directed 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
• a closed loop servo system responsive to an input command representing a desired amount of light to pass between the vanes, the servo system responsive to the input command for producing separate motor control signals for independently controlling operation of each motor to constantly rotate the vanes in unison to pass a selected amount of light between the vanes;
• in which:
• (1) the vanes are aligned on a common plane, (2) the vanes both rotate toward or away from the axis to reduce or enlarge the light opening between the vanes, (3) the width of the vanes is such that the vanes produce a slight overlap along their confronting outer edges when rotated to a closed light-blocking position aligned with the plane.