Carousel-mounted modular development units for electrographic printer

A toner developing apparatus for developing a latent image formed on the surface of a moving recording medium comprising

• a rotating carousel for supporting a plurality of toner units and carrying a toner medium and supported on said carousel for rotation therewith in a maintained upright position,
• drive means to rotate said carousel and selectively position one of said toner units in a printing position wherein the toner unit so positioned may develop said latent image,
• drive means to engage a toner unit at said printing position to apply said toner medium to said recording medium,
• each of said units including a rotatable applicator/wipe roll and a toner pump within each unit, said drive means to apply said toner medium includes means to drive said roll in a direction opposite to the direction of movement of said recording medium and means to drive said toner pump after activation of said roll drive means,
• said toner pump drive means is initially driven at a velocity greater than its normal operating velocity to quickly establish a toner meniscus at said roll and said recording medium.

The method of developing a latent electrographic image on the surface of a moving recording medium comprising the steps of

• providing a modular developing unit containing a toner medium and having an applicator/wipe roll for engaging the surface of the recording medium and applying toner, via toner pump in the unit, to the recording medium surface in a region forming an apex at the point where the roll engages the recording medium surface,
• rotating the roll in a direction opposite to the direction of movement of the recording medium,
• operating the toner pump at a velocity that exceeds its normal operating velocity to quickly establish a toning meniscus at the apex, and
• thereafter reducing the velocity of the toner pump to its normal operating velocity.

A recording medium cutter apparatus comprising a stationary cutting blade and a rotatable cutting blade mounted on a shaft and positioned relative to said stationary blade to sever a recording medium positioned therebetween,

• motor drive means coupled to said shaft to rotate said rotatable cutting blade,
• a cam secured to said shaft and having an instep on the surface thereof,
• stop means moveably mounted adjacent to said cam and having bias means to maintain said stop means in said cam instep to prevent the rotation of said rotatable cutting blade by said motor drive means,
• means to engage and remove said stop means from said cam instep and permit the operation of said motor drive means to rotate said rotatable cutting blade one revolution.
• said last mentioned means being disengaged prior to the completion of said one revolution to permit said stop means to lodge within said cam instep and terminate the rotation of said rotatable cutting blade.

A modular self-contained toner unit for removably mounting between spaced carousel frame members supported on support means in an electrographic printer comprising

• a housing containing a lower section for holding toner and an upper section for supporting developer means to engage the surface of a recording medium when said toner unit is positioned at a development station,
• pumping means in said lower section for directing toner to said developer means to be applied by said developer means to said recording medium surface,
• means for rotatably mounting both ends of said toner unit relative to said carousel frame members,
• releasable attaching means forming part of said mounting means at one of said toner unit ends, said releasable attaching means when placed in its retracted position releasing said one end from its carousel frame member permitting removal of said unit from between said carousel frame members,
• developer drive means mounted on said support means for releasably intercoupling with said developer means when the latter is positioned in said development station, and
• toner pump drive means mounted on said support means for releasably intercoupling with said pumping means when the latter is positioned in said development station.

A modular self-contained toner unit for removably mounting between spaced carousel frame members supported on support means in an electrographic printer comprising

• a housing containing a lower section for holding toner and an upper section for supporting developer means to engage the surface of a recording medium when said toner unit is positioned at a development station.
• pumping means in said lower section for directing toner to said developer means to be applied by said developer means to said recording medium surface,
• means for rotatably mounting both ends of said toner unit relative to said carousel frame members,
• stabilizing means supported on said support means having a forward bearing member extending toward one end of said toner unit,
• a bearing member on one end of said toner unit having a cavity positioned between two cam surfaces,
• means to bias said forward bearing member into engagement with said toner unit bearing member upon movement of said toner unit toward final positioning at said development station,
• said toner unit bearing member in biased engagement with one of said toner unit cam surfaces upon said movement of said toner unit toward final positioning at said development station and in biased engagement in said bearing member cavity when said toner unit is in its final position at said development station to hold firm the positioning of said toner unit in said development station.

A releasably engagable drive apparatus for a developer roll mounted for rotational movement in a developer unit comprising:

• a shaft extending axially from one end of said roll and a cross member extending through said shaft perpendicular to the axis of said shaft to form a T-coupler,
• drive means mounted adjacent to and in axial alignment with said T-coupler and comprising a motor with a motor shaft having a claw coupler mounted at the outer end thereof,
• said claw coupler comprising a cylindrical shaped hollow body with orthogonally aligned pairs of grooves formed at its forward end defining an axially aligned claw member between adjacent grooves, one side of each claw member having a flat surface and the other side of each claw member having a curved portion extending toward the outer end of each of said one side flat surface to form a curved surface on the forward end of each claw member and
• means to advance and retract said claw members into and out of engagement with said T-coupler.