Wrist mounted communicator

A highly sensitive communicator that disposes an IC serving as a high frequency noise generator to reduce the effect of the high-frequency noise. The active surfaces of a high-frequency analog IC and a signal-processing digital IC face toward a liquid crystal display panel disposed at the front of the communicator and do not face a loop antenna formed in a watchband at the rear. Therefore, even if the high-frequency analog IC and the signal-processing digital IC emit high-frequency noise from the active surfaces the high-frequency noise is unlikely to reach the loop antenna. Therefore, the communicator has high sensitivity.

TECHNICAL FIELD 
The present invention relates to communication apparatuses such as 
receivers and transmitters. The present invention more specifically 
relates to a technology for effectively reducing an effect of 
high-frequency noise generated by an integrated circuit (hereinafter 
called IC) in a communication apparatus, on an antenna body. 
BACKGROUND ART 
As a portable transmitter or receiver, a watch with an FM radio and a 
watch-shaped individual-selective-calling receiver have been known. In 
such a watch-type apparatus, an electrically conductive plate member or 
film is put in a watchband for mounting an apparatus body at a wrist. 
Therefore, when the watchband is mounted at the wrist, a loop antenna is 
formed by the plate member or film. 
In such a communication apparatus, as typically shown in FIG. 9(b), the 
apparatus body includes a circuit board 73 on which a high-frequency 
analog IC 93B for transmission or receiving and a signal-processing 
digital IC 94B which is driven by a driving signal having a frequency as 
high as several MHz are mounted. These ICs (collectively indicated by 
A.cndot.B-IC in the figure) are wire-bonded on the rear surface section 
732 of the circuit board 73 at the rear surface side (side where the 
entire or most part of a loop antenna 4 is disposed) of the circuit board 
73. At the front surface side (side where a liquid crystal display panel 6 
is disposed) of the circuit board 73, a display digital IC 95B (indicated 
by C-IC in the figure) which is driven by a several-tens-of-kHz driving 
signal is mounted on the front surface section 721 of a circuit board 72 
by wire bonding. 
Through various examinations into the effect of high-frequency noise in a 
wrist-mount-type communication apparatus, the inventor of this application 
found that sensitivity is low when the high-frequency analog IC 93B or the 
signal-processing digital IC 94B is wire-bonded to the rear surface 
section 732 of the circuit board 73. In other words, irrespective of 
high-frequency noise generated from the active surface (meaning a surface 
on which leads are exposed, a wiring surface, and a device surface) 930B 
or 940B of the high-frequency analog IC 93B or the signal-processing 
digital IC 94B, when the high-frequency analog IC 93B or the 
signal-processing digital IC 94B is disposed conventionally such that the 
active surface 930B or 940B faces the loop antenna 4, it is because the 
loop antenna 4 is susceptible to the effect of the high-frequency noise. 
In consideration of the foregoing problem, it is an object of the present 
invention to provide a highly sensitive communication apparatus which 
reduces the effect of high-frequency noise generated from the active 
surface of an IC by appropriately disposing the IC that serves as a noise 
source. 
DISCLOSURE OF INVENTION 
To solve the foregoing problem, the object of the present invention is 
achieved through the provision of a communication apparatus including a 
board on which an integrated circuit generating high-frequency noise is 
mounted; and an antenna body the entire or most of which is disposed on 
one board-surface side of the board, wherein the integrated circuit is 
mounted on the board such that the active surface thereof directs at the 
direction opposite the direction where the entire or most of the antenna 
body is disposed against the board. 
In a communication apparatus according to the present invention, since the 
active surface of an integrated circuit generating high-frequency noise 
directs at the direction opposite the direction where the entire or most 
of the antenna body is disposed, even if the integrated circuit emits 
high-frequency noise from its active surface, the high-frequency noise 
unlikely reaches the antenna body. Therefore, the sensitivity of the 
communication apparatus can be increased. 
To make such a communication apparatus to be of a wrist-mount-type, the 
communication apparatus is, for example, provided with an apparatus body 
in which a side on which a display screen is formed is set to a front 
surface side and a watchband extending from the apparatus body toward the 
rear surface side for mounting the apparatus body to the wrist, and the 
antenna body is formed in the watchband, and the board is disposed at the 
rear surface side of the display screen in the apparatus body. 
In the present invention, an integrated circuit generating the 
high-frequency noise includes, for example, a high-frequency analog 
integrated circuit having at least one of functions between a transmission 
function and a receiving function, a signal-processing digital integrated 
circuit driven by a high-frequency driving signal, or a CPU. 
In the present invention, to mount the integrated circuit such that the 
active surface directs at the direction opposite the direction where the 
entire or most of the antenna body is disposed against the board, the 
integrated circuit is, for example, face-down-bonded to a board surface 
where the entire or most of the antenna body is disposed in the board. 
The integrated circuit may be wire-bonded to the board surface opposite the 
surface where the entire or most of the antenna body is disposed in the 
board so that the active surface of the integrated circuit directs at the 
direction opposite the direction where the entire or most of the antenna 
body is disposed against the board. 
In the present invention, face-down bonding means all methods for 
electrically connecting electrodes by adhering a surface electrode or a 
wiring lead mounted in advance on a semiconductor chip for an integrated 
circuit to a wiring electrode formed on a board with both front surfaces 
thereof facing each other, and includes flip-chip bonding.

REFERENCE NUMERALS 
1: Wrist-mount-type communication apparatus 
2: Apparatus body 
4: Loop antenna (antenna body) 
4R, 4L: Watchbands 
5: Circuit assembly 
6: Liquid crystal display panel (display screen) 
41, 42: Antenna bodies 
71, 72, 73, 74, 75: Circuit boards 
90A, 95A: Digital ICs for processing display data 
91A, 93A, 96, 98: High-frequency analog ICs generating high-frequency noise 
92A, 94A, 97, 99: Signal-processing digital ICs generating high-frequency 
noise 
910A, 920A, 930A, 940A, 960, 970, 980, 990: Active surfaces of ICs 
BEST MODE FOR CARRYING OUT THE INVENTION 
According to the drawings, an embodiment of the present invention will be 
described. 
Embodiment 1 
FIG. 1 is a view indicating a configuration of a wrist-mount-type 
communication apparatus to which the present invention is applied. 
In FIG. 1, the wrist-mount-type communication apparatus 1 is formed by an 
apparatus body 2 which has a liquid crystal display panel 6 (display 
screen) disposed on the front surface side thereof and a pair of 
watchbands 4R and 4L. Each of the watchbands 4R and 4L is mounted to both 
ends of the apparatus body at each watchband main end. 
These wrist bands can be connected to each other at each sub end by a 
buckle 41. 
The watchbands 4R and 4L are provided with electrically conductive plates 
thereinside and mounted at the wrist of the user. When the sub ends of the 
watchbands 4R and 4L are connected, they form a loop antenna 4 (antenna 
body). 
The apparatus body 2 is formed by a front-surface-side casing 3a and a rear 
cover 3b secured to the rear side of the casing 3a at the rear side of the 
apparatus body 2. A circuit assembly 5 is built in the apparatus body 2, 
which is formed by the casing 3a and the rear cover 3b. 
FIG. 2(a) and (b) show the front and rear surfaces of the circuit assembly 
5, respectively. FIG. 3(a) is a typical cross-sectional view of the 
circuit assembly 5 taken on line IV-IV' shown in FIG. 2. 
In these figures, main components of the circuit assembly 5 are laminated 
in the thickness direction of the apparatus body 2 in its inside. In other 
words, in the circuit assembly 5, the liquid crystal display panel 6, a 
circuit board 71, and a battery 8 for driving the circuit are disposed in 
the thickness direction. 
The loop antenna 4 is electrically and mechanically connected to terminal 
sections of the circuit board 71. These terminal sections are connected to 
a digital IC 90A. The loop antenna 4 is held by the watchbands 4R and 4L, 
and extends to the rear surface side of the circuit board 71. The loop 
antenna 4 is not necessarily directly secured to the circuit board 71. The 
loop antenna 4 needs to be electrically connected to terminal sections of 
the circuit board 71. It may be pressure-connected, or wire-connected with 
leads. 
Various electronic components are mounted on the circuit board 71. Of the 
front surface side (side where the liquid crystal display panel 6 is 
disposed) thereof and the rear surface side (side where the entire or most 
of the loop antenna 4 is disposed), to the front surface section 711 
opposing the liquid crystal display panel 6, the digital IC 90A (indicated 
by C-IC in the figure) for controlling display operations in the liquid 
crystal display unit 6 is adhered and electrically connected by face-down 
bonding method such as flip chip bonding. 
At the rear surface side where most part of the loop antenna 4, which is 
formed by connecting the sub ends of the watchbands 4R and 4L mounted at 
the wrist, is disposed, on the rear surface section 712 of the circuit 
board 71, a high-frequency analog IC 91A having transmission and receiving 
functions and a signal-processing digital IC 92A are mounted. These ICs 
(collectively indicated by A.cndot.B-IC in the figure) are also 
face-down-bonded to the circuit board 71. Therefore, the active surfaces 
910A and 920A of the high-frequency analog IC 91A and the 
signal-processing digital IC 92A face the circuit board 71 (side where the 
liquid crystal display panel 6 is disposed) and do not face the direction 
where most of the loop antenna 4 is disposed. 
The digital IC 90A for liquid crystal display is driven by a driving signal 
having a frequency as relatively low as several tens of kHz, and does not 
generate high-frequency noise. On the other hand, since the high-frequency 
analog IC 91A transmits and receives high-frequency signals in the range 
of several tens of MHz to several hundreds of MHz, it generates 
high-frequency noise as shown by arrow A. Since the signal-processing 
digital IC 92A includes a digital circuit for sampling a received signal 
before analog/digital conversion and a phase locked loop circuit, and is 
driven by a driving signal having a frequency as high as several MHz, it 
generates high-frequency noise as indicated by arrow A. 
In this embodiment, however, since the high-frequency analog IC 91A and the 
signal-processing digital IC 92A both generating high-frequency noise are 
disposed at the rear surface side of the circuit board 71 with the active 
surfaces 910A and 920A thereof directing the side (side where the liquid 
crystal display panel 6 is disposed) of the circuit board 71 and not 
directing the direction where most of the loop antenna 4 is disposed, the 
effect of the high-frequency noise generated by them is unlikely to reach 
the loop antenna 4. Therefore, the wrist-mount-type communication 
apparatus 1 to which the present invention is applied has high 
sensitivity. 
To examine the noise reduction effect, the structure in the present 
embodiment shown in FIG. 3(a) and a structure in a comparison case shown 
in FIG. 3(b) in which a digital IC 90B (indicated by C-IC in the figure) 
for controlling display operations in the liquid crystal display panel 6 
is face-down bonded to the rear surface section 712 of the circuit board 
71 and a high-frequency analog IC 91B and a signal-processing digital IC 
92B both serving as high-frequency noise generation sources are face-down 
bonded to the front surface section 711 of the circuit board 71 are 
relatively compared in terms of sensitivity in receiving. 
In FIG. 4, receiving sensitivity measured in a frequency range of 87.4 MHz 
to 108.2 MHz in the wrist-mount-type communication apparatus 1 according 
to the present embodiment in which the high-frequency analog IC 91A and 
the signal-processing digital IC 92A both serving as high-frequency noise 
generation sources are face-down bonded to the rear surface section 712 of 
the circuit board 71 to direct the active surfaces 910A and 920A thereof 
toward the liquid crystal display panel 6 is indicated by a broken line 
L1A. In FIG. 4, receiving sensitivity measured in a frequency range of 
87.4 MHz to 108.2 MHz in the wrist-mount-type communication apparatus 1 
according to the comparison case in which the high-frequency analog IC 91B 
and the signal-processing digital IC 92B both serving as high-frequency 
noise generation sources are face-down bonded to the front surface section 
711 of the circuit board 71 to direct the active surfaces 910B and 920B 
thereof toward the loop antenna 4 is indicated by a broken line L1B. 
The vertical axis in FIG. 4 indicates relative sensitivity with the 
reference sensitivity level being set to 0 dB. 
As clearly understood from this figure, in the structure according to the 
present embodiment, high-frequency noise emitted from the active surfaces 
910A and 920A of the high-frequency analog IC 91A and the 
signal-processing digital IC 92A is not emitted toward the loop antenna 4 
as shown by arrow A in FIG. 3(a), whereas in the structure according to 
the comparison case, high-frequency noise emitted from the active surfaces 
910B and 920B of the high-frequency analog IC 91B and the 
signal-processing digital IC 92B is emitted toward the loop antenna 4 as 
shown by arrow B in FIG. 3 (b). Therefore, in the structure according to 
the present embodiment, sensitivity is higher in any frequencies ranging 
from 87.4 MHz to 108.2 MHz than in the structure according to the 
comparison case. In other words, sensitivity in the structure according to 
the present embodiment is -2.5 dB in relative sensitivity against the 
reference sensitivity, whereas sensitivity in the structure in the 
comparison case is -1.0 dB in relative sensitivity against the reference 
sensitivity. According to the structure of the present embodiment, 
sensitivity increases by 1.5 dB. 
In FIG. 5, in a wrist-mount-type communication apparatus using the 
structure according to the present embodiment, sensitivity in the 
communication apparatus which has the circuit board 71 on which each IC is 
mounted as is is indicated by a broken line L3A, sensitivity in the 
communication apparatus in which the side of the circuit board 71 at which 
the high-frequency analog IC 91A is mounted is entirely shielded and a 
circuit-driving battery 8 is disposed such that it faces the rear surface 
side of the circuit board 71 is indicated by a broken line L4A, 
sensitivity in the communication apparatus in which both sides of the 
circuit board 71 are entirely shielded and the circuit-driving battery 8 
is disposed such that it faces the rear surface side of the circuit board 
71 is indicated by a broken line L5A, and sensitivity in the communication 
apparatus in which a shield plate to which a driving voltage is applied is 
disposed at the rear surface side of the circuit board 71, and a 
circuit-driving battery 8 and a rear cover are disposed such that they 
face the rear surface side of the circuit board 71 is indicated by a 
broken line L6A. 
In FIG. 6, in a wrist-mount-type communication apparatus using the 
structure according to the comparison case, sensitivity in the 
communication apparatus which has the circuit board 71 on which each IC is 
mounted as is is indicated by a broken line L3B, sensitivity in the 
communication apparatus in which the side of the circuit board 71 at which 
the high-frequency analog IC 91B is mounted is entirely shielded and the 
circuit-driving battery 8 is disposed such that it faces the rear surface 
side of the circuit board 71 is indicated by a broken line L4B, 
sensitivity in the communication apparatus in which both sides of the 
circuit board 71 are entirely shielded and the circuit-driving battery 8 
is disposed such that it faces the rear surface side of the circuit board 
71 is indicated by a broken line L5B, and sensitivity in the communication 
apparatus in which a shield plate to which a driving voltage is applied is 
disposed at the rear surface side of the circuit board 71, and the 
circuit-driving battery 8 and a rear cover are disposed such that they 
face the rear surface side of the circuit board 71 is indicated by a 
broken line L6B. 
The vertical axes in FIGS. 5 and 6 indicate relative sensitivity with the 
reference sensitivity level being set to 0 dB. 
In FIGS. 5 and 6, in either structure, the more shielding measures are 
applied, the higher the sensitivity becomes. As shown in Table 1 in which 
sensitivity obtained from the sensitivity characteristics shown in FIGS. 5 
and 6 is compared, in any conditions, sensitivity is higher in the 
structure according to the present invention. 
Table 1 also indicates sensitivity measured with another sample in the 
wrist-mount-type communication apparatuses having the same structures and 
the same specifications, in parentheses. Values shown in Table 1 are the 
averages of measured values indicated in each line in FIGS. 5 and 6. 
TABLE 1 
______________________________________ 
Difference in 
Structure in sensitivity of 
present Structure in 
present 
Item embodiment comparison 
embodiment to 
Structure [dB] case [dB] comparison case 
______________________________________ 
Circuit board 
0.83 3.64 2.81 
only (-0.17) (1.87) (2.49) 
Shielding -0.57 1.97 2.54 
high-frequency 
(-1.82) (1.54) (3.36) 
analog IC side + 
battery 
Shielding both 
-0.42 1.26 1.68 
sides of (-1.91) (1.17) (3.08) 
circuit board + 
battery 
Shielding rear 
-0.62 0.86 1.48 
surface side 
(-2.52) (-0.67) (1.85) 
with driving 
voltage + 
battery + rear 
cover 
______________________________________ 
In FIG. 7, with this another sample in a wrist-mount-type communication 
apparatus using the structure according to the present embodiment, 
sensitivity in the communication apparatus which has the circuit board 71 
on which each IC is mounted as is is indicated by a broken line L3A, 
sensitivity in the communication apparatus in which the side of the 
circuit board 71 at which the high-frequency analog IC 91A is mounted is 
entirely shielded and the circuit-driving battery 8 is disposed such that 
it faces the rear surface side of the circuit board 71 is indicated by a 
broken line L4A, sensitivity in the communication apparatus in which both 
sides of the circuit board 71 are entirely shielded and the 
circuit-driving battery 8 is disposed such that it faces the rear surface 
side of the circuit board 71 is indicated by a broken line L5A, and 
sensitivity in the communication apparatus in which a shield plate to 
which a driving voltage is applied is disposed at the rear surface side of 
the circuit board 71, and the circuit-driving battery 8 and a rear cover 
are disposed such that they face the rear surface side of the circuit 
board 71 is indicated by a broken line L6A. 
In FIG. 8, with this another sample in a wrist-mount-type communication 
apparatus using the structure according to the comparison case, 
sensitivity in the communication apparatus which has the circuit board 71 
on which each IC is mounted as is is indicated by a broken line L3B, 
sensitivity in the communication apparatus in which the side of the 
circuit board 71 at which the high-frequency analog IC 91B is mounted is 
entirely shielded and the circuit-driving battery 8 is disposed such that 
it faces the rear surface side of the circuit board 71 is indicated by a 
broken line L4B, sensitivity in the communication apparatus in which both 
sides of the circuit board 71 are entirely shielded and the 
circuit-driving battery 8 is disposed such that it faces the rear surface 
side of the circuit board 71 is indicated by a broken line L5B, and 
sensitivity in the communication apparatus in which a shield plate to 
which a driving voltage is applied is disposed at the rear surface side of 
the circuit board 71, and the circuit-driving battery 8 and a rear cover 
are disposed such that they face the rear surface side of the circuit 
board 71 is indicated by a broken line L6B. 
The vertical axes in FIGS. 7 and 8 indicate relative sensitivity with the 
reference sensitivity level being set to 0 dB. 
As a result, as understood from Table 1, FIG. 7, and FIG. 8, it has been 
confirmed that the advantage of sensitivity increase by use of the 
structure to which the present invention is applied is repeatedly shown 
even if measurement is performed with another sample. 
Embodiment 2 
Since a wrist-mount-type communication apparatus according to the present 
embodiment is substantially the same in structure as the wrist-mount-type 
communication apparatus according to the embodiment 1 except that an IC is 
wire-bonded to a circuit board, it will be described by referring to FIG. 
1 and FIG. 2. 
In FIG. 1, the wrist-mount-type communication apparatus 1 is formed by an 
apparatus body 2 which has a liquid crystal display panel 6 (display 
screen) disposed on the front surface side thereof and a pair of 
watchbands 4R and 4L. Each of the watchbands 4R and 4L is mounted to both 
ends of the apparatus body at each watchband main end. These wrist bands 
can be connected to each other at each sub end by a buckle 41. 
The watchbands 4R and 4L are provided with electrically conductive plates 
thereinside and mounted at the wrist of the user. When the sub ends of the 
watchbands 4R and 4L are connected, they form a loop antenna 4 (antenna 
body). A circuit assembly 5 is built in the apparatus body 2. 
FIG. 2(a) and (b) show the front and rear surfaces of the circuit assembly 
5, respectively. FIG. 9(a) is a typical cross-sectional view of the 
circuit assembly 5 taken on line IV-IV' shown in FIG. 2. 
In these figures, main components of the circuit assembly 5 are laminated 
in the thickness direction of the apparatus body 2 in its inside. In other 
words, in the circuit assembly 5, the liquid crystal display panel 6, a 
first circuit board 72, a second circuit board 73 mounted to the rear 
surface side of the first circuit board, and a battery 8 for driving the 
circuits are disposed in the thickness direction. On the rear surface side 
(side where the entire or most of the loop antenna 4 is disposed) of the 
second circuit board 73, a digital IC 95A (indicated by C-IC in the 
figure) for controlling display operations in the liquid crystal display 
unit 6 is wire-bonded to the rear surface section 732 thereof. 
Various electronic components are mounted on the first circuit board 72. On 
the front surface side (side where the liquid crystal display panel 6 is 
disposed) thereof, to the front surface section 721, a high-frequency 
analog IC 93A having transmission and receiving functions and a 
signal-processing digital IC 94A are mounted. These ICs (collectively 
indicated by A.cndot.B-IC in the figure) are also wire-bonded to the first 
circuit board 72. Therefore, the active surfaces 930A and 940A of the 
high-frequency analog IC 93A and the signal-processing digital IC 94A face 
the liquid crystal display panel 6 and do not face the direction where the 
loop antenna 4 is disposed. 
The digital IC 95A for liquid crystal display is driven by a driving signal 
having a frequency as relatively low as several tens of kHz, and does not 
generate high-frequency noise. On the other hand, since the high-frequency 
analog IC 93A transmits and receives high-frequency signals in the range 
of several tens of MHz to several hundreds of MHz, it generates 
high-frequency noise as shown by arrow C. Since the signal-processing 
digital IC 94A includes a digital circuit for sampling a received signal 
before analog/digital conversion and a phase locked loop circuit, and is 
driven by a driving signal having a frequency as high as several MHz, it 
generates high-frequency noise as indicated by arrow C. 
In this embodiment, however, the high-frequency analog IC 93A and the 
signal-processing digital IC 94A both generating high-frequency noise are 
disposed at the front surface side of the first circuit board 72 with the 
active surfaces 930A and 940A thereof directing toward the liquid crystal 
display panel 6 and not directing at the loop antenna 4. Therefore, the 
effect of the high-frequency noise generated by them is unlikely to reach 
the loop antenna 4. Therefore, the wrist-mount-type communication 
apparatus 1 to which the present invention is applied has high 
sensitivity. 
To examine the noise reduction effect, the structure in the present 
embodiment shown in FIG. 9(a) and a conventional structure shown in FIG. 
9(b) in which a digital IC 95B for controlling display operations in the 
liquid crystal display panel 6 is wire-bonded to the front surface section 
721 of the first circuit board 72 and a high-frequency analog IC 93B and a 
signal-processing digital IC 94B both serving as high-frequency noise 
generation sources are wire-bonded to the rear surface section 732 of the 
second circuit board 73 are relatively compared in terms of sensitivity in 
receiving. 
As a result, sensitivity is -3.0 dB in relative sensitivity against the 
reference sensitivity in the wrist-mount-type communication apparatus 1 
according to the present embodiment in which the high-frequency analog IC 
93A and the signal-processing digital IC 94A both serving as 
high-frequency noise generation sources are wire-bonded to the front 
surface section 721 of the first circuit board 72 to direct the active 
surfaces 930A and 940A thereof toward the liquid crystal display panel 6. 
In contrast, sensitivity is -2.0 dB in relative sensitivity against the 
reference sensitivity in the conventional wrist-mount-type communication 
apparatus in which the high-frequency analog IC 93B and the 
signal-processing digital IC 94B both serving as high-frequency noise 
generation sources are wire-bonded to the rear surface section 732 of the 
second circuit board 73 to direct the active surfaces 930B and 940B 
thereof toward the loop antenna 4. In other words, in the structure 
according to the present embodiment, high-frequency noise emitted from the 
active surfaces 930A and 940A of the high-frequency analog IC 93A and the 
signal-processing digital IC 94A is not emitted toward the loop antenna 4 
as shown by arrow C in FIG. 9(a), whereas in the conventional structure, 
high-frequency noise emitted from the active surfaces 930B and 940B of the 
high-frequency analog IC 93B and the signal-processing digital IC 94B is 
emitted toward the loop antenna 4 as shown by arrow D in FIG. 9(b). 
Therefore, in the structure according to the present embodiment, 
sensitivity is higher by 1.0 dB than in the comparison case. 
In FIG. 10, in the wrist-mount-type communication apparatus 1 using the 
structure according to the present embodiment, sensitivity in the 
communication apparatus as a final product is indicated by a broken line 
L7A, sensitivity in the communication apparatus in which a rear cover to 
be disposed on the rear surface side of the second circuit board 73 is 
removed is indicated by a broken line L8A, sensitivity in the 
communication apparatus in which the rear cover and a battery 8 for 
driving the circuits both to be disposed at the rear surface side of the 
second circuit board 73 are removed is indicated by a broken line L9A, and 
sensitivity in the communication apparatus formed only by the first and 
second circuit boards 72 and 73 is indicated by a broken line L10A. 
In FIG. 11, in the conventional wrist-mount-type communication apparatus, 
sensitivity in the communication apparatus as a final product is indicated 
by a broken line L7B, sensitivity in the communication apparatus in which 
the rear cover to be disposed on the rear surface side of the second 
circuit board 73 is removed is indicated by a broken line L8B, sensitivity 
in the communication apparatus in which the rear cover and the battery 8 
for driving the circuits both to be disposed at the rear surface side of 
the second circuit board 73 are removed is indicated by a broken line L9B, 
and sensitivity in the communication apparatus formed only by the first 
and second circuit boards 72 and 73 is indicated by a broken line L10B. 
The vertical axes in FIGS. 10 and 11 indicate relative sensitivity with the 
reference sensitivity level being set to 0 dB. 
In FIGS. 10 and 11, in either structure, the more the apparatus used 
approaches the final product, the higher the sensitivity becomes. As shown 
in Table 2 in which sensitivity obtained from the sensitivity 
characteristics shown in FIGS. 10 and 11 is compared, in any conditions, 
sensitivity is higher in the structure according to the present invention. 
Table 2 also indicates sensitivity measured with another sample in the 
wrist-mount-type communication apparatuses having the same structures and 
the same specifications, in parentheses. Values shown in Table 2 are the 
averages of measured values indicated in each line in FIGS. 10 and 11. 
TABLE 2 
______________________________________ 
Difference in 
Structure in sensitivity of 
present Structure in 
present 
Item embodiment comparison 
embodiment to 
Structure [dB] case [dB] comparison case 
______________________________________ 
Final product 
-3.18 -1.95 1.23 
(-3.04) (-2.41) (0.63) 
With rear -1.06 0.64 1.70 
cover being 
(2.00) (-0.85) (1.15) 
removed 
Wither rear 
3.62 4.49 0.87 
cover and (1.70) (2.72) (1.02) 
battery being 
removed 
Formed only by 
3.56 4.78 1.22 
circuit boards 
(2.14) (2.66) (0.52) 
______________________________________ 
In FIG. 12, with this another sample in a wrist-mount-type communication 
apparatus 1 using the structure according to the present embodiment, 
sensitivity in the communication apparatus as a final product is indicated 
by a broken line L7A, sensitivity in the communication apparatus in which 
the rear cover to be disposed on the rear surface side of the second 
circuit board 73 is removed is indicated by a broken line L8A, sensitivity 
in the communication apparatus in which the rear cover and the battery 8 
for driving the circuits both to be disposed at the rear surface side of 
the second circuit board 73 are removed is indicated by a broken line L9A, 
and sensitivity in the communication apparatus formed only by the first 
and second circuit boards 72 and 73 is indicated by a broken line L10A. 
In FIG. 13, with this another sample in a conventional wrist-mount-type 
communication apparatus, sensitivity in the communication apparatus as a 
final product is indicated by a broken line L7B, sensitivity in the 
communication apparatus in which the rear cover to be disposed on the rear 
surface side of the second circuit board 73 is removed is indicated by a 
broken line L8B, sensitivity in the communication apparatus in which the 
rear cover and the battery 8 for driving the circuits both to be disposed 
at the rear surface side of the second circuit board 73 are removed is 
indicated by a broken line L9B, and sensitivity in the communication 
apparatus formed only by the first and second circuit boards 72 and 73 is 
indicated by a broken line L10B. 
The vertical axes in FIGS. 12 and 13 indicate relative sensitivity with the 
reference sensitivity level being set to 0 dB. 
As a result, as understood from Table 2, FIG. 12, and FIG. 13, it has been 
confirmed that the advantage of sensitivity increase by use of the 
structure according to the present embodiment is repeatedly shown even if 
measurement is performed with another sample. 
Embodiment 3 
In the embodiments 1 and 2, in a wrist-mount-type communication apparatus 
including an apparatus body which has as the front surface side a side on 
which a display screen is formed and an antenna body formed in a watchband 
for mounting the apparatus body to the wrist, ICs generating 
high-frequency noise are mounted on a circuit board such that the active 
surfaces thereof direct at the display screen side (side opposite the side 
where the entire or most of the antenna body is disposed against the 
circuit board). As shown in FIGS. 14(a) and 14(b), the present invention 
can also be applied to a communication apparatus in which ICs and an 
antenna body are formed on the same circuit board. 
FIG. 14(a) is a typical perspective view indicating arrangement of an 
antenna body and a circuit board in a communication apparatus according to 
embodiment 3. FIG. 14(b) is a side view of the structure. 
As shown in FIG. 14(a), the communication apparatus according to the 
present embodiment includes a circuit board 74 on which various electronic 
components are mounted and an antenna body 41 formed on one surface 741 of 
the circuit board 74. Among the electronic components, ICs generating 
high-frequency noise, such as a high-frequency analog IC 96 and a 
signal-processing digital IC 97, are all mounted on the same surface 741 
as the antenna body 41 is mounted, against the circuit board 74. 
Since the high-frequency analog IC 96 and the signal-processing digital IC 
97 are face-down-bonded to the circuit board 74 as shown in FIG. 14(b), 
the active surfaces 960 and 970 thereof face the direction opposite the 
direction where the antenna body 41 is disposed against the circuit board 
74. Therefore, in the communication apparatus according to the present 
embodiment, if high-frequency noise is emitted from the active surfaces 
960 and 970 of the high-frequency analog IC 96 and the signal-processing 
digital IC 97 as indicated by arrow E, the effect of the high-frequency 
noise is unlikely to reach the antenna body 41 and sensitivity is high. 
Embodiment 4 
FIG. 15(a) is a typical perspective view indicating arrangement of an 
antenna body and a circuit board in a communication apparatus according to 
embodiment 4. FIG. 15(b) is a side view of the structure. 
As shown in FIG. 15(a), the communication apparatus according to the 
present embodiment includes a circuit board 75 on which various electronic 
components are mounted and an antenna body 42 formed on one surface 751 of 
the circuit board 75. Among the electronic components, ICs generating 
high-frequency noise, such as a high-frequency analog IC 98 and a 
signal-processing digital IC 99, are all mounted on the surface 752 
opposite the surface on which the antenna body 42 is mounted against the 
circuit board 75. 
Since the high-frequency analog IC 98 and the signal-processing digital IC 
99 are wire-bonded to the circuit board 75 as shown in FIG. 15(b), the 
active surfaces 980 and 990 thereof face the direction opposite the 
direction where the antenna body 41 is disposed against the circuit board 
75. Therefore, also in the communication apparatus according to the 
present embodiment, if high-frequency noise is emitted from the active 
surfaces 980 and 990 of the high-frequency analog IC 98 and the 
signal-processing digital IC 99 as indicated by arrow F, the effect of the 
high-frequency noise is unlikely to reach the antenna body 941 and 
sensitivity is high. 
Other Embodiments 
In each embodiment, a loop antenna is used as an antenna body. A slit may 
be formed in the longitudinal direction of the antenna body to form a slot 
antenna. 
Not only in a case in which an antenna body is formed on a circuit board on 
which an IC is mounted but also in a case in which an antenna body is 
formed on a base member different from a circuit board, when an IC 
generating high-frequency noise is mounted on the circuit board such that 
the active surface thereof directs at the direction opposite the direction 
where the entire or most of the antenna body is disposed against the 
circuit board, if high-frequency noise is emitted from the active surface 
of the integrated circuit, the effect of the high-frequency noise unlikely 
reach the antenna body and an advantage of high sensitivity is obtained. 
Industrial Applicability 
In a communication apparatus according to the present invention, the active 
surface of an integrated circuit generating high-frequency noise directs 
at the direction opposite the direction where the entire or most of the 
antenna body is disposed against the circuit board. In other words, the 
active surface of the integrated circuit generating high-frequency noise 
does not direct toward the antenna. Therefore, if high-frequency noise is 
emitted from the active surface of the integrated circuit, the 
high-frequency noise is unlikely reach the antenna body, and the 
communication apparatus having a high sensitivity is implemented. 
In addition, the present invention can be applied to any types of 
communication apparatuses, such as a watch having an FM radio, a 
watch-type individual-selective-calling receiver, a pocket pager, a 
portable phone, a PHS.