Graphic recording apparatus compensated for record medium velocity changes

In graphic recording apparatus including means for moving a record medium along a first path relative to a medium-marking means at a substantially constant average velocity, and including means for moving said marking means over a second path which is substantially normal to said first path to cause said marking means to produce a recorded image on said medium, the improvement comprising

• sensing means responsive to said movement of said medium along said first path for sensing the instantaneous velocity of said medium along said first path,
• signal producing means coupled to said sensing means and responsive to said sensed velocity for producing a signal which is representative of solely the direction, extent, and duration of short term changes in said sensed velocity from said constant average velocity, and
• deflection control means coupled to said signal producing means and to said marking means and responsive to said signal for moving said marking means along said first path in a direction, at a rate, and for a time dependent upon said signal to maintain the instantaneous relative velocity between said medium and said marking means along said first path substantially constant notwithstanding said short term changes in said sensed velocity,
• whereby the density of said recorded image in the direction along said first path is substantially unaffected by said short term velocity changes.

In graphic recording apparatus including means for moving a record medium along a first path relative to a medium-marking means at a substantially constant average velocity, and including means for moving said marking means over a second path which is substantially normal to said first path to cause said marking means to produce a recorded image on said medium, the improvement comprising

• sensing means responsive to said movement of said medium along said first path for sensing the instantaneous velocity of said medium along said first path,
• signal producing means coupled to said sensing means and responsive to said sensed velocity for producing a velocity error signal which is representative of solely the difference between said instantaneous and average velocities of said medium,
• integrating means coupled to said signal producing means and responsive to said error signal for producing an integral signal of a magnitude which represents the time integral of said error signal, and
• deflection control means coupled to said integrating means and to said marking means and responsive to said integral signal for positioning said marking means along said first path in accordance with the magnitude of said integral signal to maintain the instantaneous relative velocity between said medium and said marking means along said first path substantially constant notwithstanding short term changes in said sensed velocity from said average velocity,
• whereby the density of said recorded image in the direction along said first path is substantially unaffected by said short term velocity changes.

In graphic recording apparatus including means for moving a record medium along a first path relative to the face of a cathode ray tube at a substantially constant average velocity, and including means for moving the beam of said tube over a second path which is substantially normal to said first path to cause said beam to produce a recorded image on said medium, the improvement comprising

• sensing means responsive to said movement of said medium along said first path for sensing the instantaneous velocity of said medium along said first path,
• signal producing means coupled to said sensing means and responsive to said sensed velocity for producing a signal which is representative of soley the direction, extent, and duration of short term changes in said sensed velocity from said constant average velocity, and
• beam deflection control means coupled to said signal producing means and to said beam and responsive to said signal for moving said beam along said first path in a direction, at a rate, and for a time dependent upon said signal to maintain the instantaneous relative velocity between said medium and said beam along said first path substantially constant notwithstanding said short term changes in said sensed velocity,
• whereby the density of said recorded image in the direction along said first path is substantially unaffected by said short term velocity changes.

In graphic recording apparatus including means for moving a record medium along a first path relative to the face of a cathode ray tube at a substantially constant average velocity, and including means for moving the beam of said tube over a second path which is substantially normal to said first path to cause said beam to produce a recorded image on said medium, the improvement comprising

• sensing means responsive to said movement of said medium along said first path for sensing the instantaneous velocity of said medium along said first path,
• signal producing means coupled to said sensing means and responsive to said sensed velocity for producing a velocity error signal which is representative of solely the difference between said instantaneous and average velocities of said medium,
• integrating means coupled to said signal producing means and responsive to said error signal for producing an integral signal of a magnitude which represents the time integral of said error signal, and
• beam deflection control means coupled to said integrating means and to said beam and responsive to said integral signal for positioning said beam along said first path in accordance with the magnitude of said integral signal to maintain the instantaneous relative velocity between said medium and said beam along said first path substantially constant notwithstanding short term changes in said sensed velocity from said average velocity,
• whereby the density of said recorded image in the direction along said first path is substantially unaffected by said short term velocity changes.

In graphic recording apparatus including means for moving a light-sensitive record sheet along a sheet travel path relative to and across the fiber optics strip of a fiber optics cathode ray tube at a substantially constant average velocity, and including first beam deflection control means for moving the beam of said tube over a marking path which is substantially normal to said sheet travel path and which is along the phosphor coating on the inboard side of said strip, thereby to cause said beam to produce a recorded image on and along said sheet, the improvement comprising

• sensing means responsive to said movement of said sheet along said sheet travel path for sensing the instantaneous velocity of said sheet along the last-mentioned path,
• signal producing means coupled to said sensing means and responsive to said sensed velocity for producing a velocity error signal which is representative of solely the difference between said instantaneous and average velocities of said sheet,
• integrating means coupled to said signal producing means and responsive to said error signal for producing an integral signal of a magnitude which represents the time integral of said error signal, and
• second beam deflection control means coupled to said integrating means and to said beam and responsive to said integral signal for positioning said beam along a compensating path which is substantially normal to said marking path and which is hence along said sheet travel path, the position of said beam along said compensating path with respect to a datum position being determined by the magnitude of said integral signal,
• whereby the instantaneous relative velocity between said sheet and said beam along said sheet travel path is maintained substantially constant, notwithstanding short term changes in said sensed velocity from said average velocity, to prevent the density of said recorded image along said sheet travel path from being affected by said short term velocity changes.

Graphic recording apparatus, comprising

• drive means arranged to move a record medium along a medium travel path, said drive means including medium velocity feedback means for causing said drive means to move said medium along said medium travel path at a substantially constant average velocity,
• medium-marking means located along said medium travel path in marking relationship to said medium,
• first moving means coupled to said marking means for moving the latter along a medium marking path which is substantially normal to said medium travel path to cause said marking means to produce a recorded image on said medium,
• second moving means coupled to said marking means for moving the latter along said medium travel path, and
• compensating means coupled to said medium and responsive to the instantaneous velocity of said medium along said medium travel path, including means for producing a signal which represents solely short term changes in said velocity, and coupled to said second moving means for positioning said marking means along said medium travel path in response to said signal to maintain a substantially constant instantaneous relative velocity between said medium and said marking means along said medium travel path,
• whereby the density of said recorded image in the direction of said medium travel path is substantially unaffected by said short term changes in said instantaneous velocity of said medium from said constant average velocity.