PRINTHEAD HAVING HEATED SHIELD PLATE
FIG7B is a sectional perspective through a second channel of the fluid coupling  FIG5 is an exploded perspective of a main body of the printhead with inlet and outlet couplings
Each ink entering the fluid coupling 8 has a carefully controlled respective hydrostatic pressure (e.g. by virtue of an upstream pressure regulator) and it is important that the relative hydrostatic pressures of the inks are not changed as the inks flow through the fluid coupling. For example, the four inks may enter the inlets ports 9A-9D with equal hydrostatic pressures and it is desirable that these inks exit the outlet ports 11A-11D into the manifold 25 with equal hydrostatic pressures. A degree of pressure drop is, to some extent, inevitable as each ink experiences flow resistance (i.e. viscous drag) through the fluid coupling 8; however, it is important that the pressure drops are equalized for all inks despite the longer fluidic paths for the two inks flowing through the two inner inlet ports 9B and 9C. Accordingly, as shown in FIG7B, a fluid channel 12B connecting the inlet port 9B with the outlet port 11B has a roof 13B sloped upwards from towards the inlet port 9B. A roof 13C of a corresponding fluidic channel connecting the inlet port 9C and the outlet port 11C is, likewise, sloped upwards towards the inlet port 9C. By contrast the fluid channel 12A connecting inlet port 9A with the outlet port 11A does not have a similarly sloped roof, requiring the fluid to turn through a tighter angle without assistance from a more curved fluid path.  Referring to FIG5, the main body 17 is itself a two-part machined structure comprising an elongate manifold 25 and a complementary cover plate 27. The manifold 25 functions as a carrier having a unitary lower surface for mounting both the first and second rows 14 and 16 of printhead chips. The manifold 25 is received between a pair of opposed flanges 29, which extend downwardly from opposite longitudinal sides of the cover plate 27. The flanges 29 are configured for snap-locking engagement with complementary snap-locking features 26 of the manifold 25 to form the assembled main body 17.
exploded, perspective view, sectional view
29
flanges flange
5
alignment notch
10
coupling body
25
manifold
['1. An inkjet printhead (1) comprising: a manifold (25) having a plurality of ink outlets (50) defined in a manifold surface; a plurality of printhead chips (70) mounted to the manifold surface (52) via a shim (66), the printhead chips being aligned with the ink outlets; a PCB (18) mounted to the manifold surface and offset from the ink outlets, the PCB being electrically connected to the printhead chips, wherein a lower surface of the PCB is coplanar with a lower surface of the shim; and a shield plate (20) bonded to the PCB and part of the shim, the shield plate covering the PCB, wherein: the shield plate has one face in thermal contact with the PCB and an exposed opposite face defining a lower surface of the printhead; and the shim has at least one void region (68) offset from the printhead chips, the void region thermally isolating part of the shield plate from the manifold.']