Fig 7 Uem & Upp Sim Connections; Fig 8 Speaker Interface - Nokia RH-9 Series Ccs Technical Documentation

RH-9
CCS Technical Documentation System Module & UI
(Ear Simulator Type 4195, Low Leakage).
Three different types of A-covers is used for RH-9: Standard cover, gaming cover and DC-
out cover. The gaming and DC-out covers is accessory covers. The std. A-cover and the
gaming cover comply with the same TA rules since they cannot be identified HW- and
SW-wise; this means that they match acoustical wise. However, the DC-out cover can be
identified, meaning that this type of cover is equalised separately.
In the assembly process the earpiece is placed into the lightguide from the front of the
phone. On top of this the metal frame is mounted.
The lightguide have stoppers in the bottom which lift the earpiece 0.3mm from the PWB
to provide leakage to the back.
On top of the lightguide is a metal frame which is the only visible part (in the earpiece
area) when the A-cover is removed. The metal frame covers the front of the earpiece to
provide protection against damage from fingers etc. The metal frame contain two acous-
tical holes in the area over the earpiece. These are placed as close to the vertical centre
of the phone as the design allows, in order to secure a sufficient sound pressure.
The metal frame have double-sided sealing in the earpiece area 1) downwards in order to
provide sealing and pressure against the top of the earpiece 2) upwards to provide seal-
ing to the A-cover. There is an opening in this gasket in the area on top of the metal
frame to provide better leakage to the internal volume.
The A-cover have a total of 5 acoustical holes positioned on a straight vertical line
through the centre of the phone. All holes are equal in size, elliptical in shape (each hole
approximates the area of a Ø1.3 hole). The three holes in top of the A-cover are posi-
tioned close to the metal frame hole in order to control loudness.
The A-cover includes a ring underneath which seals against the metal frame gasket. The
ring has a well defined opening of 5 mm (width). The opening has one main purpose: to
allow a dust shield to be mounted. Secondly the opening will provide better conditions
for obtaining good leak tolerant performance, than if only one A-cover hole was present.
All covers are optimised for the use of a dust shield, the specific type is Saatitech
PEC120/41.
Below the earpiece is the PWB, where 4 holes will secure proper leakage to the volume
between the PWB and the internal antenna. However since the PWB doesn't stretch all
the way up to the top of the phone there will also be some natural leakage where the
PWB is missing.
Microphone electrical interface
In RH-9 a differential bias circuit, driven directly from the MICB1 bias output with exter-
nal RC-filters is chosen. This is a solution that has previously been used with success in
other phones. The RC filter (220 Ω, 4.7µF) is scaled to provide damping at 217 Hz. 217 Hz
Issue 1 11/02 ãNokia Corporation Page 35