Printhead chassis assembly

1. A printhead chassis assembly for a chip based printhead, comprising:

a chassis which supports two spaced apart bearing moldings between which extend a feed roller and an exit roller;

the chassis supporting a duct cover in which is formed a number of inlet ports which are adapted to receive liquid ink;

the duct cover sealing against a distribution molding, the distribution molding having a longitudinal axis and a number of elongated ducts running in parallel along the axis, each duct being associated with a port;

all of the ducts are sealed against and in fluid communication with an upper layer of a laminated ink distribution structure; and

a longitudinal air duct within which is located an air valve molding formed as a channel with a series of apertures in its base;

the apertures corresponding to air passages formed in the air duct so that the apertures can be brought into and out of alignment with the passages to selectively allow pressurized air through;

the air valve molding reciprocating within the air duct;

a spring maintaining a sealing inter-engagement of a bottom of the air valve molding with the base of the air duct to prevent leakage;

the laminated ink distribution structure having a first layer in which is formed a number of first holes, each first hole being in registry with a lower duct portion;

the laminated ink distribution structure having a number of subsequent layers, each subsequent layer having vertical passages and transverse channels for bringing a fluid from a duct, via the first layer, to one of a number of printhead chips located as an array in a chip restraining layer;

the chips arranged to print onto a sheet of media carried by the feed roller and the exit roller.

2. The assembly of claim 1 , wherein:

the air valve molding has a cam follower extending from one end, which engages an air valve cam surface on an end cap of a multi-purpose platen so as to selectively move the air valve molding longitudinally within the air duct according to a rotational positional of the platen.

3. The assembly of claim 2 , wherein:

the platen may be rotated between printing, capping or blotting positions.

4. The assembly of claim 3 , wherein:

the platen has a position for printing in which the cam holds the air valve in an open position to supply air to the print chip; and

when the platen is rotated to a non-printing position, it seals off a plurality of micro-apertures in the nozzle guard.

5. The assembly of claim 2 , wherein:

the platen member has an exposed blotting portion, the portion being an exposed part of a body of blotting material located inside the platen.

6. The assembly of claim 2 , wherein:

the platen member has a platen surface and a capping portion and an exposed blotting portion which are separated from one another by about 120 degrees of rotation.

7. The assembly of claim 3 , further comprising:

a capping assembly which is supported at each end by a bearing molding; each bearing molding having a pair of vertical rails;

the four vertical rails enabling the capping assembly to move vertically.

8. The assembly of claim 7 , wherein:

a spring under either end of the capping assembly biases the assembly into a raised position, maintaining a cam in contact with a spacer projection;

the printhead chips being capped when not is use by a full-width capping member using an elastomeric seal 86 .