Cluster module and its assembling method

On a rear surface of a cluster bezel, a module circuit body is formed with, for example, an FPC (flexible printed circuit). Thereafter, on the rear surface of the cluster bezel, an instrument board, a right-side switch section, and a left-side switch section are mounted. In this operation, connecting terminals on a base board provided for the instrument board, the right-side switch section, and the left-side switch section are brought into contact with the contact portions of the FPC, so that the meters on the instrument board are electrically connected to the right-side switch section and the left-side switch section.

BACKGROUND OF THE INVENTION 
This invention relates to a cluster module which can be readily assembled 
and wired, and a method of assembling the cluster module. 
It is well known in that art, for instance in mounting instruments, 
switches, etc. on the instrument panel of a motor vehicle, a cluster 
module formed by using a cluster bezel is mounted on the instrument panel. 
With respect to a cluster module of this type, the present inventor has 
proposed a "meter module" disclosed in Japanese Patent Unexamined 
Publication No. Hei 7-96774. As shown in FIG. 9, the meter module 100 
(renumbered) comprises: an instrument board 101 in which meters, display 
lamps, and their drive circuit are built; the drive circuit 102; a 
collective control circuit 103 including control circuits provided for 
mobile electrical units including the aforementioned meters, display 
lamps, etc.; and an electrical junction box 104 in which electrical wires 
are connected to apply electric power, input and output signals, and 
grounding to the mobile electrical units. 
Further in FIG. 9, reference numerals 105 through 108 designate switches 
provided for head-lamps etc. Those switches 105 through 108 are fixedly 
fitted in mounting openings 110 in a rear frame 109 which is paired with a 
cluster bezel (or finished panel, not shown). Further in FIG. 9, reference 
numeral 111 designates an auxiliary wire harness which is provided for the 
module in addition to an in-panel harness. The auxiliary wire harness 111 
has a module connecting connector 112 and an in-panel harness connecting 
connector 113 at the middle, and connectors 114 at both ends which are 
directly connected to electrical units. The meter module 100 thus designed 
is simple in arrangement. 
On the other hand, in the case where a switch module 121 is mounted on the 
cluster bezel 120 as shown in FIG. 10, the switch module 121 is covered 
with a lid 122; that is, a box-shaped unit is formed. The box-shaped unit 
is fixedly mounted on the cluster bezel 120 with screws (not shown). A 
wire harness 123 is bundled, and fastened to the cluster bezel 120 by a 
pin 124, and a connector 125 of the wire harness 123 is connected to the 
cluster bezel 120. 
The meter module 110 shown in FIG. 9 is advantageous in that it is simple 
in arrangement; however, it suffers from a problem that, since various 
parts must be mounted on the cluster bezel from both sides, the assembling 
work takes time and labor. 
In the case of FIG. 10, the wire harness 123 must be laid being dragged in 
and out, as a result of which it may be damaged or at worst 
short-circuited. In addition, it is necessary to use the pin 124 to 
fixedly secure the wire harness. Those difficulty may occur with the 
above-described meter module 100. 
SUMMARY OF THE INVENTION 
Accordingly, an object of this invention is to eliminate the 
above-described difficulties. More specifically, an object of the 
invention is to provide a cluster module which can be readily assembled 
and wired, and which prevents the wire harness from being damaged or 
short-circuited, and which is reduced in the number of components, and a 
method of assembling the cluster module. 
The foregoing object of the invention has been achieved by the provision of 
a cluster module, which, according to one aspect of the invention, 
comprises: 
a cluster bezel to be mounted on an instrument panel; 
a circuit body formed on the rear surface of the cluster bezel; and 
electronic components which are mounted or the rear surface of the cluster 
bezel, and electrically connected to the circuit body. 
In the cluster module, the circuit body is formed on the rear surface of 
the cluster bezel, and it is connected to the switch module. This feature 
eliminates the difficulty accompanying the prior art that the wire harness 
is dragged in and out when laid, and accordingly it is damaged and at 
worst short-circuited. 
In the cluster module, preferably the circuit body is a flexible printed 
circuit. 
In the cluster module, the circuit body is the flexible printed circuit. 
Hence, it can be formed with ease. 
In the cluster module, preferably the circuit body is formed by double-slot 
molding. 
In the cluster module, the circuit body is formed by double-shot molding, 
and therefore it can be readily formed. 
Furthermore, in the cluster module, preferably the circuit body is formed 
by plating. 
In the cluster module, the circuit body is formed by plating, and therefore 
it can be formed with ease. 
Moreover, the above-described object of the invention has been achieved by 
the provision of a method of assembling a cluster module, in which, 
according to another aspect of the invention, 
after a circuit body is formed on the rear surface of a cluster bezel to be 
mounted on an instrument panel, 
electronic component are mounted on the rear surface of the cluster bezel, 
and 
the electronic components are electrically connected to the circuit body. 
As was described above, in the method, after the circuit body is formed on 
the rear surface of the cluster bezel, the electronic components are 
electrically connected to the circuit body. This feature eliminates the 
difficulty accompanying the prior art that the wire harness is dragged in 
and out when laid, and simplifies the installation of the electronic 
components.

DETAILED DESCRIPTION OF THE INVENTION 
A cluster module according to the invention, and its assembling method will 
be described with reference to the accompanying drawings. 
FIG. 1 is an exploded perspective view of the cluster module according to 
the invention, FIG. 2 is a sectional view taken along line 2--2 in FIG. 1, 
FIG. 3 is a perspective view showing an FPC (flexible printed circuit) in 
the cluster module of the invention, and FIG. 4 is a sectional view taken 
along line 4--4 in FIG. 3. Furthermore, FIG. 5 is a diagram showing a 
surface contact terminal in the cluster module according to the invention, 
FIG. 6 is a diagram showing a procedure of assembling the cluster module 
according to the invention, FIG. 7 is a perspective view showing a plated 
circuit in the cluster module according to the invention, and FIG. 8 is a 
sectional view showing a module circuit body formed by double-shot 
molding. 
The cluster module 1 of the invention is shown in FIG. 1. In FIG. 1, 
reference numeral 10 designates a cluster bezel mounted on an instrument 
panel (not shown) of a motor vehicle; and 11, a module circuit body, 
namely, an FPC (flexible printed circuit) 11 is welded to the rear surface 
(R) of the cluster bezel 10 at predetermined position along the 
protrusions on the rear surface. The FPC 11 is formed through insert 
molding fused concurrently with formation of the bezel in a state of 
temporary fixation to a metal mold. On the other hand, a defroster 12 is 
mounted on the rear surface of the cluster bezel 10. 
On the other hand, an electronic module 14 is mounted on the rear surface 
of an instrument board 13 having a variety of meters. The instrument board 
13 is fixedly mounted on the rear surface of the cluster bezel 10 at the 
middle with screws 15. In addition, a right-side switch section 16 is 
fixedly secured to one end portion of the rear surface of the cluster 
bezel with screws 17, while a left-side switch section 18 to the other end 
portion of the rear surface with screws 19. 
The right-side switch section 16 includes a hazard switch, a clock switch, 
an air conditioner switch, and an audio satellite switch which are 
operated by a driver or a passenger, whereas the left-side switch section 
18 includes light switches such as a main light switch, a fog lamp switch, 
and an automatic lamp switch which are operated by the driver only. 
The cluster bezel 10 has a connector guide section 20 on the rear surface 
which is U-shaped in section. Contact portions 22 of the FPC 11 are 
provided on the inner surface of one guide rail 21 of the connector guide 
section 20. 
As shown in FIG. 3, the guide rail 21 has a through-hole 27 formed in its 
base portion, and the contact portions 22 are inserted into the 
through-hole 27 from outside and extended along the inside of the guide 
rail 21. The contact portions 22, as shown in FIG. 4, are bent over the 
outer end portion of the guide rail 21 in such a manner as to embrace it. 
On the other hand, as shown in FIG. 2, a base board 23 is provided for the 
instrument board 13, the right-side switch section 16, and the left side 
switch section 18. The base board 23 has a connector 26 which has 
surface-contact terminals 24 which are brought into contact with the 
contact portions 22 of the FPC 11. 
Simultaneously when the instrument board 13, the right-side switch section 
16, and the left-side switch selection 18 are mounted on the rear surface 
of the cluster bezel 10, the surface contact terminals 24 are brought into 
contact with the contact portions 22 of the FPC 1, so that the meters on 
the instrument board 13 are electrically connected to the switches of the 
right-side switch section 16, and those of the left-side switch section 
18. 
Each of the surface contact terminals 24 includes a U-shaped stress 
absorbing portion 25 as shown in FIG. 5. Hence, even if the connector 
guide portion 20 and the surface contact terminals 24 are somewhat shifted 
in position from each other, the surface contact terminals 24 can be 
readily inserted in the connector guide section 20. 
The cluster module 1 thus designed can be assembled according to an 
assembling procedure shown in FIG. 6. 
First, the FPC 11 is welded to the rear surface of the cluster bezel 10, 
and the defroster 12 is mounted thereon (Step 31). 
Next, the instrument board 13, the right-side switch section 16, and the 
left-side switch section 18 are mounted on the rear surface of the cluster 
bezel 10 (Steps 32 through 34), so that the surface contact terminals 24 
of the base board 23 provided for the instrument board 13, the right-side 
switch section 16 and the left-side switch section 18 are brought into 
contact with the FPC 11. 
Under this condition, an electrical conduction test, and a system 
inspection are carried out (Step 35). Thus, the cluster module has been 
manufactured. Thereafter, it is packed (Step 36), and then shipped out 
(Step 37). 
As was described above, in the cluster module 1, the FPC 11, which is the 
module circuit body, is provided on the rear surface of the cluster bezel 
10; and the instrument board 13, the right-side switch section 16, and the 
left-side switch section 18 are also mounted on the rear surface of the 
cluster bezel 10, which makes it possible to readily install the 
electrical components. 
With the cluster module of the invention, unlike the conventional one, it 
is unnecessary to drag in and out the wire harnesses. Accordingly, the 
cluster module of the invention is free from the difficulty that the wire 
harness is damaged and at worst short-circuited. Furthermore, the cluster 
module of the invention dispenses with the wire harness and accordingly 
the pins for fixing it, which results in a reduction in the number of 
components. 
In the above-described embodiment of the invention, the module circuit body 
is the FPC 11; however, the invention is not limited thereto or thereby. 
That is, the module circuit body may be formed of a plated circuit 40 
which is formed by plating as shown in FIG. 7. In this case, the plated 
circuit 40 is extended over the guide rail 21 in such a manner that its 
end portion embraces the guide rail 21, thus providing contact portions 41 
which are brought into contact with the surface contact terminals 24 (FIG. 
2). In addition, as shown in FIG. 8, a module circuit body 50 may be 
formed by double-shot molding (so-called "MID (Molded Interconnection 
Device) molding method") in which a material capable of making plating and 
a material incapable of making plating are integrally formed on the 
surface of the bezel through two shots. According to this double-shot 
molding, the module circuit body 50 having contact portions which are 
brought into contact with the surface contact terminals 24 (FIG. 2), are 
made of electrically conductive material; whereas the cluster bezel body 
51, on which the module circuit body 50 is formed, is made of electrically 
non-conductive material. 
The formation of the module circuit body can be readily achieved by plating 
or double-shot molding. 
As was described above, the cluster module of the invention comprises: a 
cluster bezel to be mounted on an instrument panel; a circuit body formed 
on the rear surface of the cluster bezel; and electronic components which 
are mounted on the rear surface of the cluster bezel, and electrically 
connected to the circuit body. 
Accordingly, in the cluster module, the circuit body is formed on the rear 
surface of the cluster bezel, and it is connected to the electronic 
components. This feature eliminates the difficulty accompanying the prior 
art that, when laid, the wire harness is damaged and at worst 
short-circuited while being dragged in and out. In addition, the cluster 
module dispenses with the wire harness and accordingly its mounting pins. 
Hence, the cluster module is reduced in the number of components and in 
total weight as much, and the electronic components can be installed with 
ease. 
In the cluster module, the circuit body may be formed of a flexible printed 
circuit. Hence, the circuit body can be readily formed. 
In the cluster module, the circuit body may be formed by plating, and 
therefore it can be formed with ease. 
In the cluster module, the circuit body may be formed by double-shot 
molding, and therefore it can be readily formed. 
In the method of assembling the cluster module, after the circuit body is 
formed on the rear surface of the cluster bezel to be mounted on the 
instrument panel, the electronic components are mounted on the rear 
surface of the cluster bezel, and the electronic components are 
electrically connected to the circuit body. 
Accordingly, in the method, after the circuit body is formed on the rear 
surface of the cluster bezel, the electronic components are connected to 
the circuit body. This feature eliminates the difficulty accompanying the 
prior art that, when laid, the wire harness is dragged in and out, and 
simplifies the installation of the electronic components.