Cross Reference to Related Applications
[0001] The present invention contains subject matter related to Japanese Patent Application
No.
2007-314546 filed in the Japanese Patent Office on December 5, 2007, the entire contents of which
being incorporated herein by reference.
BACKGROUND
1. Technical Field
[0002] The present invention relates to a mobile device, and more particularly, to a mobile
device configured to receive television broadcasting such as terrestrial digital broadcasting
and the like.
2. Related Art
[0003] There are mobile phones that have a function of receiving television broadcasting.
Particularly, for the function, a mobile phone that has an antenna in a housing and
performs tuning control using a variable tuning circuit has been developed (see
JP-A-2006-41840).
[0004] There is a mobile phone that has first and second housings, a display screen provided
to the one of the housings, and operating keys provided to the other one thereof (see
JP-A-2006 - 332795). The first and second housings of the mobile phone are connected by means such as
a hinge to rotate relative to each other, so that a positional relationship therebetween
is variable.
SUMMARY
[0005] However, circuit boards having conductive foils in ground patterns and components
with metal such as circuit elements and connectors shielded by metal are included
in the first and second housings. In addition, when an angle between the first and
second housings is changed by the rotation therebetween, a reception condition of
the antenna is also changed. Therefore, as described above, the positional relationship
between the first and second housings of the mobile phone can be changed and the reception
condition of the antenna can also be changed due to the changed positional relationship,
so that there is a problem in that good reception is difficult.
[0006] It is desirable to provide a mobile device capable of performing good reception even
when a positional relationship between multiple housings of the mobile device is changed.
[0007] According to an aspect of the invention, the mobile device having first and second
housings of which positional relationship is variable, includes: in the first and
second housings, an antenna element for receiving television signals; a matching circuit
including a variable capacitance element to perform matching with the antenna element;
a television signal receiver circuit connected to the matching circuit; a control
circuit controlling a tuning voltage to be supplied to the variable capacitance element;
and a sensing unit detecting the positional relationship between the first and second
housings, wherein the control circuit controls the tuning voltage according to the
positional relationship between the first and second housings represented by the detection
result of the sensing unit.
[0008] With such a configuration, the tuning voltage according to the positional relationship
between the first and second housings which influences the reception condition is
supplied to an antenna module, so that accurate reception is possible even when the
positional relationship between the first and second housings is changed.
[0009] In the mobile device according to the aspect of the invention, at least one of the
first and second housings may include a display for displaying images demodulated
from the received television signal.
[0010] In this case, in the mobile device having the first and second housings of which
the positional relationship is variable and at least one is provided with the display
to display the received television broadcasting, a user holds the other side housing
(the first housing) and moves the housing having the display in order to use the mobile
device. Specifically, in the mobile device of which the housing has the display, various
relationships between the first and second housings exist as the positional relationship
therebetween. In this situation, a tuning voltage according to the corresponding positional
relationship is supplied to the antenna module, so that accurate reception according
to the positional relationship between the first and second housings is always possible.
[0011] In the mobile device according to the embodiment of the invention, the control circuit
may include a storage unit for storing a correspondence table representing correspondence
between the positional relationship of the first and second housings and the tuning
voltage. With such a configuration, the tuning voltage can be selected according to
the positional relationship between the first and second housings by referring to
the correspondence table.
[0012] In the mobile device according to the embodiment of the invention, the sensing unit
may include a magnet provided to at least one of the first and second housings and
a magnetism sensor provided to the other one of the first and second housings.
[0013] With such a configuration, when the first and second housings are in a predetermined
state, a positional relationship between the magnet provided to the one housing and
the sensor provided to the other housing is allowed to be a predetermined relationship,
so that the positional relationship between the housings can be detected by the output
from the sensor.
[0014] According to the embodiment of the present invention, good reception is possible
even when the positional relationship between multiple housings of the mobile device
is changed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015]
Fig. 1A is a front view illustrating the outer appearance of a mobile phone in a closed
state according to a first embodiment of the invention, and Fig. 1B is a side view
illustrating the outer appearance of the mobile phone in the closed state.
Fig. 2A is a front view illustrating the outer appearance of the mobile phone in a
use state according to the first embodiment of the invention, and Fig. 2B is a side
view illustrating the outer appearance of the mobile phone in the use state.
Fig. 3 is a perspective view illustrating a circuit board included in a second housing
and an antenna module provided to a surface of the circuit board.
Fig. 4 is a perspective view illustrating the outer appearance of the antenna module.
Fig. 5 is a connection diagram illustrating a configuration of a matching circuit
of the antenna module.
Fig. 6 is a block diagram illustrating a configuration of the antenna module and a
receiver circuit.
Fig. 7 is a view illustrating a relationship between tuning voltages used in the use
state and tuning voltages used in the closed state corresponding to each reception
channel.
Fig. 8 is a view for explaining tuning voltage supply means in the receiver circuit.
Fig. 9 is a view illustrating changes in voltage standing wave ratio (VSWR) characteristics
due to changes in the tuning voltages.
Fig. 10A is a front view illustrating the outer appearance of a mobile phone in a
closed state according to a second embodiment of the invention, and Fig. 10B is a
side view illustrating the outer appearance of the mobile phone in the closed state.
Fig. 11A is a front view illustrating the outer appearance of the mobile phone in
a use state according to the second embodiment of the invention, and Fig. 10B is a
side view illustrating the outer appearance of the mobile phone in the use state.
Fig. 12A is a front view illustrating the outer appearance of the mobile phone in
a folded-back state according to the second embodiment of the invention, and Fig.
10B is a side view illustrating the outer appearance of the mobile phone in the folded-back
state.
Fig. 13 is a block diagram illustrating a configuration of an antenna module and a
receiver circuit according to the second embodiment.
Fig. 14 is a view illustrating a relationship between tuning voltages used in the
use state, tuning voltage used in the closed state, and tuning voltage used in the
folded-back state corresponding to each reception channel.
Fig. 15 is a front view illustrating the outer appearance of a mobile phone in a horizontally
long display state according to another embodiment.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0016] Hereinafter, a mobile device according to embodiments of the invention will be described
in detail with reference to the accompanying drawings.
First Embodiment
[0017] Figs. 1 and 2 are views illustrating the appearance of a mobile phone 10 that is
an example of the mobile device according to the embodiment of the invention. The
mobile phone 10 includes a first housing 20 having an operating surface 21 provided
with operating keys 22 for inputting phone numbers and the like, a microphone (not
shown), and the like, and a second housing 30 having an operating surface 31 provided
with a liquid crystal display unit 32, operation keys 33, a speaker (not shown), and
the like.
[0018] The second housing 30 is slidably supported with respect to the first housing 20
by a slide member (not shown). Fig. 1 illustrates a closed state in which the first
and second housings 20 and 30 overlap with each other. In this state, since the second
housing 30 overlaps with the operating surface 21 of the first housing 20, the outer
size of the mobile phone 10 constructed with the first and second housings 20 and
30 is reduced so as to enable the mobile phone 10 to be easily stored. On the other
hand, Fig. 2 illustrates a use state in which the first and second housings 20 and
30 in the closed state in Fig. 1 slide past each other and the operating keys 22 provided
to the operating surface 21 of the first housing 20 are exposed. As illustrated in
Fig. 2, the operating surfaces 21 and 31 of the first and second housings 20 and 30,
respectively, face the same direction in the use state.
[0019] When a user does not use the mobile phone 10, the user may allow the first and second
housings 20 and 30 that can slide past each other to be in the closed state for portability,
and when the user uses the mobile phone 10, the user may allow the first and second
housings 20 and 30 to be in the use state so that the liquid crystal display unit
32 and the operating keys 22 are exposed in the same direction and can be simultaneously
used.
[0020] The mobile phone 10 includes an antenna module 40 in the second housing 30 to receive
television broadcasting (for example, terrestrial digital broadcasting) through the
antenna module 40. The antenna module 40 is used for receiving television broadcasting,
and an antenna module (not shown) for phone calls is additionally provided. For example,
the antenna module for phone calls is included in the first housing 20 and provided
in the vicinity of a lower portion in the figure. As described above, the antenna
module 40 for receiving television broadcasting and the antenna module for phone calls
are separated as much as possible from each other to prevent interference therebetween.
[0021] Fig. 3 is a perspective view illustrating a circuit board 50 included in the second
housing 30 and the antenna module 40 provided to a surface of the circuit board 50.
As illustrated in Fig. 3, the circuit board 50 is a board having a shape to be included
in the second housing 30 (see Figs. 1 and 2) and a base material 50a of which at least
one surface is formed in a ground pattern 50b. A cut-out portion is formed at a part
of the ground pattern 50b, and the antenna module 40 is directly attached to the base
material through the cut-out portion.
[0022] As illustrated in Fig. 4, the antenna module 40 includes an antenna element 40a constructed
with a base body 41 having a rectangular parallelepiped shape, a belt-like radiation
conductor 42 wound on the base body 41 in a helical pattern, and a matching circuit
40b constructed with an LC series resonant circuit 43 including, for example, a varactor
diode, a coil, and the like and formed at the surface of the base body 41. The matching
circuit 40b can change a resonance frequency by changing capacitance of the varactor
diode and equivalently changing reactance L, thereby changing a reception frequency
band. The matching circuit 40b is connected to the ground pattern 50b with a ground
line 45 and also connected to a tuner (not shown) with a power supply line 46. According
to the embodiment, the base body 41 is composed of a resin material such as liquid
crystal polymer but it is not limited thereto and may be composed of, for example,
a dielectric material, a magnetic material, or a combination thereof. In addition,
the antenna may have a film shape. Additionally, instead of the radiation conductor
42 wound in the helical pattern, a plurality of conductors having a ring shape may
be worn, or a monopole-type conductor may be provided.
[0023] Fig. 5 is a connection diagram illustrating a circuit configuration of the matching
circuit 40b. For the antenna element 40a, the matching circuit 40b includes a resistor
R11, a pair of varactor diodes D11 and D12, coils L11 and L12, a condenser C11, and
a resistor R13. The matching circuit 40b changes a voltage to be supplied to the varactor
diodes D11 and D12 by changing a tuning voltage V
tune described later, thereby chanting the reception frequency band. Accordingly, a desired
channel can be selected. At the same time, the tuning voltage can be adjusted (described
later) according to a state (the closed state or the use state) of the first and second
housings 20 and 30 of the mobile phone 10, and optimal tuning characteristics according
to the state of the housings can be obtained.
[0024] Fig. 6 is a connection diagram illustrating a configuration of the antenna module
40 described above with reference to Fig. 4 and a receiver circuit 60 connected to
the antenna module 40. As illustrated in Fig. 6, the matching circuit 40b of the antenna
module 40 is connected to the receiver circuit 60 with the power supply line 46.
[0025] The receiver circuit 60 includes a mobile tuner 65 having a tuner 61 and a demodulation
integrated circuit (IC) 62, and a control circuit 63. The tuner 61 performs frequency
conversion on a radio frequency (RF) signal received from the antenna module 40 into
a signal having a low frequency to perform digital demodulation. The demodulation
IC 62 demodulates the reception signal output from the tuner 61 and outputs the demodulated
signal to the control circuit 63. The control circuit 63 decodes an image signal by
performing, for example, moving picture experts group (MPEG) decoding on the signal
demodulated by the demodulation IC 62 and outputs the decoded image signal to the
liquid crystal display unit 32. Accordingly, the images of television broadcasting
received through the antenna module 40 are displayed on the liquid crystal display
unit 32. In addition, the control circuit 63 performs processing such as changing
a channel of the received television broadcasting according to operation results input
through the operating keys 22 or 33.
[0026] The demodulation IC 62 is configured to transmit the tuning voltage V
tune for allowing a frequency band of a channel selected by the user to be the reception
frequency to the matching circuit 40b of the antenna module 40 so as to tune the frequency
band received through the antenna module 40 to the frequency band of the desired channel.
The demodulation IC 62 is also configured to obtain optimal tuning characteristics
according to the state of the housings by adjusting the tuning voltage V
tune according to the state (the closed state or the use state) of the first and second
housings 20 and 30 of the mobile phone 10.
[0027] Specifically, a magnetic induction type sensor 71 for detecting magnetism is provided
to the first housing 20 of the mobile phone 10. More specifically, as illustrated
in Figs. 1A and 2A, the sensor 71 is fixed to a lower right corner of the first housing
20 in the figure, and a magnet 75 is fixed to a lower right corner of the second housing
30 in the figure. Accordingly, when the first and second housings 20 and 30 are in
the closed state as illustrated in Fig. 1, the magnet 75 is close to the sensor 71.
On the contrary, when the first and second magnets 20 and 30 are in the use state
as illustrated in Fig. 2, the magnet 75 and the sensor 71 are separated from each
other. Since the sensor 71 acquires different outputs according to distances from
the magnet 75, a detecting signal output in the closed state illustrated in Fig. 1
and a detecting signal output in the use state illustrated in Fig. 2 have different
levels from each other.
[0028] Therefore, the control circuit 63 of the receiver circuit 60 (see Fig. 6) provided
to the first housing 20 can determine whether the first and second housings 20 and
30 are in the closed state or the use state, on the basis of the signal level of the
detecting signal output from the sensor 71. The control circuit 63 transmits an indicating
signal for indicating a tuning voltage value according to the closed state or the
use state on the basis of the signal level of the detecting signal output from the
sensor 71 to the demodulation IC 62. The demodulation IC 62 supplies a tuning voltage
V
tune according to the indicating signal obtained from the control circuit 63 to the matching
circuit 40b of the antenna module 40.
[0029] Specifically, as illustrated in Fig. 7, the control circuit 63 sets a tuning voltage
V
tune1 used in the closed state and a tuning voltage V
tune2 used in the use state for each channel of the television broadcasting in a correspondence
table, selects the tuning voltage as the tuning voltage V
tune1 used in the closed state or the tuning voltage V
tune2 used in the use state, according to the signal level (the signal level corresponding
to the closed state or the signal level corresponding to the use state) of the detecting
signal received from the sensor 71, and transmits an indicating signal for indicating
the selected tuning voltage to the demodulation IC 62. According to the embodiment,
the correspondence table is stored in a storage unit 63a included in the control circuit
63 but not limited thereto. For example, the correspondence table may be stored in
a storage unit provided outside the control circuit 63.
[0030] More specifically, when the user selects, for example, a channel CH1 by manipulating
the operating keys 22, the control circuit 63 determines whether the housings are
in the closed state or the use state on the basis of the detecting signal received
from the sensor 71. When the housings are in the closed state, the control circuit
63 selects the tuning voltage V
tune1 (=1.4 V) used in the closed state corresponding to the channel CH1 and transmits
the indicating signal for indicating this voltage to the demodulation IC 62. On the
contrary, when the housings are in the use state, the control circuit 63 selects the
tuning voltage V
tune2 (=1.0 V) used in the use state corresponding to the channel CH1 and transmits the
indicating signal for indicating this voltage to the demodulation IC 62.
[0031] The demodulation IC 62 transmits the tuning voltage V
tune indicated by the indicating signal received from the control circuit 63 to the matching
circuit 40b of the antenna module 40. Specifically, as illustrated in Fig. 8, the
demodulation IC 62 of the receiver circuit 60 transmits a pulse signal S
PWM having a pulse width according to the voltage indicated by the indicating signal
to a tuning voltage generation circuit 66, on the basis of the indicating signal transmitted
from the control circuit 63. The tuning voltage generation circuit 66 generates the
tuning voltage V
tune in a direct current voltage level according to the pulse width of the pulse signal
S
PWM by using a source voltage V
CC and supplies the generated tuning voltage V
tune to the matching circuit 40b through a resistor R14. In addition, a condenser C12
for blocking the direct current voltage is provided to a transmission line connecting
the matching circuit 40b to the mobile tuner 65.
[0032] Accordingly, the optimal tuning voltage V
tune according to the state (the closed state or the use state) of the housings of the
mobile phone 10 is supplied to the antenna module 40. As described above, as illustrated
in Fig. 9, since voltage standing wave ratio (VSWR) characteristics of the antenna
module 40 are changed by changing the tuning voltage V
tune, the reception frequency can be adjusted to the frequency of the channel to be received.
[0033] Otherwise, as represented by a dash line in Fig. 8, a direct current voltage S
DAC obtained by performing digital-to-analog conversion on the indicating signal transmitted
from the control circuit 63 may be supplied to the antenna module 40 as the tuning
voltage V
tune.
[0034] The operation of the mobile phone 10 having the aforementioned construction will
be described. Since the liquid crystal display unit 32 of the mobile phone 10 is exposed
in both of the closed state illustrated in Fig. 1 and the use state illustrated in
Fig. 2, the received television broadcasting can be displayed on the liquid crystal
display unit 32 in both states and provided to the user.
[0035] A positional relationship between the first and second housings 20 and 30 in the
closed state and a positional relationship between the first and second housings 20
and 30 in the use state are different from each other. The reception condition of
the antenna module 40 of the mobile phone 10 is changed according to the positional
relationship between the first and second housings 20 and 30 including the ground
pattern and various types of circuit components, so that the tuning voltage to be
applied needs to be changed according to the positional relationships therebetween.
In the receiver circuit 60 of the mobile phone 10, the optimal tuning voltages to
be adjusted to the tuning characteristics in each state of the housings are stored
in the form of the correspondence table in the storage unit 63a of the control circuit
63.
[0036] In the closed state illustrated in Fig. 1, the user can select a desired channel
by manipulating the operating keys 33 of the second housing 30 which are operable
in the closed state, and in the use state illustrated in Fig. 2, the user can select
a desired channel by manipulating the operating keys 22 of the first housing 20 which
are operable in the use state.
[0037] When a channel is selected by manipulating the operating keys 22 or 33, the control
circuit 63 of the mobile phone 10 determines the state (the closed state in Fig. 1
or the use state in Fig. 2) of the housings on the basis of the detecting signal of
the sensor 71. Thereafter, the control circuit 63 selects the tuning voltage corresponding
to the state of the housings and the channel indicated by manipulating the operating
keys 22 and 33 from the correspondence table illustrated in Fig. 7.
[0038] Accordingly, the selected tuning voltage is supplied to the antenna module 40, and
broadcast waves of the indicated channel can be received with the optimal tuning characteristics
according to the state of the housings.
[0039] In addition, when the state of the housings is changed while the television broadcasting
of the channel selected by manipulating the operating keys 22 or 33 is received, the
control circuit 63 detects the change in the state on the basis of the detecting signal
output from the sensor 71, selects a tuning voltage according to the changed state
from the correspondence table illustrated in Fig. 7, changes the current tuning voltage
to the selected tuning voltage, and supplied the selected tuning voltage to the antenna
module 40.
[0040] For example, when television broadcasting of a channel 1 is received in the closed
state (see Fig. 1), the tuning voltage supplied to the antenna module 40 is 1.4 V
as illustrated in Fig. 7. When the closed state of the housings is changed to the
use state (see Fig. 2) while the television broadcasting is received, the signal level
of the detecting signal of the sensor 71 is changed, and the control circuit 63 changes
the tuning voltage currently supplied to the antenna module 40 to the tuning voltage
of 1.0 V according to the changed state. Accordingly, even when the state of the housings
is changed while the television broadcasting is received, the optimal tuning characteristics
can be obtained.
Second Embodiment
[0041] Figs. 10 to 12 are views illustrating the appearance of a mobile phone 110 according
to a second embodiment. As compared with the mobile phone 10 according to the first
embodiment described with reference to Fig. 1, a positional relationship between first
and second housings 120 and 130 of the mobile phone 110 is different from that of
the mobile phone 10. Therefore, like reference numerals in Figs. 1 and 10 to 12 denote
like elements, and a detailed description thereof will be omitted.
[0042] Referring to Figs. 10 to 12, the mobile phone 110 includes the first and second housings
120 and 130 which are connected by a hinge 111 to rotate relative to each other in
a direction represented by an arrow a. In addition, the first and second housings
120 and 130 connected by the hinge 111 can also rotate relative to each other in a
direction represented by an arrow b.
[0043] The first housing 120 has operating keys 122 and 123 on an operating surface 121
to input phone numbers, select a channel for receiving television broadcasting, and
the like. The second housing 130 has a liquid crystal display unit 132 on a display
surface 131 to display an operating state of the mobile phone 110 and images of the
selected channel when the television broadcasting is received.
[0044] Fig. 10 illustrates a closed state in which the first and second housings 120 and
130 overlap with each other. Fig. 11 illustrates a use state in which the operating
surface 121 of the first housing 120 and the display surface 131 of the second housing
130 are exposed in the same direction. Fig. 12 illustrates a folded-back state in
which the operating surface 121 of the first housing 120 and the other surface of
the second housing 130 (the reverse side of the operating surface 131) face each other.
[0045] In the closed state illustrated in Fig. 10, the operating surface 121 of the first
housing 120 and the display surface 131 of the second housing 131 face each other.
As a result, in this state, the other surface of the second housing 130 (the reverse
side of the display surface 131) is exposed.
[0046] On the other hand, in the use state illustrated in Fig. 11, the operating surface
121 of the first housing 120 and the display surface 131 of the second housing 130
are exposed in the substantially the same direction, so that the user can manipulate
the operating keys 122 and 123 provided to the operating surface 121 of the first
housing 120, and simultaneously, can see the liquid crystal display unit 132 provided
to the display surface 131 of the second housing 130.
[0047] In the folded-back state illustrated in Fig. 12, the other surface of the second
housing 130 is allowed to overlap with the operating surface 121 of the first housing
120, so that the operating surface 121 of the first housing 120 is not exposed, and
the display surface 131 of the second housing 130 overlapping with the first housing
120 is exposed. In this state, the user can see the liquid crystal display unit 132
provided to the display surface 131 of the second housing 130.
[0048] Specifically, in the closed state illustrated in Fig. 10, the liquid crystal display
132 of the second housing 130 face the first housing 120, and a display surface of
the liquid crystal display unit 132 is externally invisible. On the other hand, in
the use state illustrated in Fig. 11 and the folded-back state illustrated in Fig.
12, the display surface of the liquid crystal display unit 132 of the second housing
130 is exposed, and the display surface is externally visible. Therefore, the user
may allow the mobile phone 110 to be in the use state illustrated in Fig. 11 or in
the folded-back state illustrated in Fig. 12 to watch information such as images of
the television broadcasting displayed on the liquid crystal display unit 132.
[0049] The antenna module 40 is provided to an end portion opposite to the other end portion
provided with the hinge 111 in the second housing 130 to receive television broadcasting.
The antenna module 40 is separately provided from an antenna module (not shown) for
phone calls. The antenna module for phone calls, for example, is included in the first
housing 120 to be adjacent to the hinge 111. As described above, the antenna module
40 for receiving television broadcasting and the antenna module for phone calls are
separated as much as possible from each other to prevent interference therebetween.
[0050] As illustrated in Figs. 10A, 11A, and 12B, the first housing 120 of the mobile phone
110 includes two magnetic induction type sensors 71 and 72 for detecting magnetism.
The first sensor 71 is provided to a lower right corner of the first housing 120 in
the figure, and the second sensor 72 is provided to a lower left corner of the first
housing 120 in the figure.
[0051] On the other hand, as illustrated in Fig. 11A, a magnet 75 is fixed to an upper right
corner of the second housing 130 with respect to the display surface 131 including
the liquid crystal display unit 132. Accordingly, when the first and second housings
120 and 130 are in the closed state as illustrated in Fig. 10, the magnet 75 is close
to the sensor 71. On the contrary, when the first and second housings 120 and 130
are in the use state as illustrated in Fig. 11, the magnet 75 and the sensors 71 and
72 are separated from each other. In addition, in the folded-back state in which the
display surface 131 is exposed as illustrated in Fig. 12, the magnet 75 and the sensor
72 are close to each other. The sensors 71 and 72 acquire different outputs according
to distances from the magnet 75. Therefore, a detecting signal output in the closed
state illustrated in Fig. 10 and a detecting signal output in the use state illustrated
in Fig. 11 have different levels from each other, and a detecting signal output in
the closed state illustrated in Fig. 10 and a detecting signal output in the folded-back
state illustrated in Fig. 11 have different levels from each other.
[0052] Accordingly, according to a combination of the signal levels of the detecting signals
of the first and second sensors 71 and 72, the state (the closed state, the use state,
or the folded-back state) of the first and second housings 120 and 130 can be determined.
As illustrated in Fig. 13 in which like reference numerals in Fig. 6 denote like elements,
the control circuit 63 stores correspondence between the combination of the signal
levels of the detecting signals S71 and S72 of the first and second sensor 71 and
72, respectively, and the state (the closed state, the use state, or the folded-back
state) of the housings of the mobile phone 110 in the form of a correspondence table,
and determines the state of the housings of the mobile phone 110 by referring to the
correspondence table on the basis of the detecting signals S71 and S72 supplied from
the first and second sensor 71 and 72, respectively.
[0053] In addition, the control circuit 63 transmits an indicating signal for indicating
a tuning voltage according to the closed state, the use state, or the folded-back
state on the basis of each signal level of the detecting signals S71 and S72 output
from the sensors 71 and 72, respectively, to the demodulation IC 62. The demodulation
IC 62 supplies the tuning voltage V
tune according to the indicating signal obtained from the control circuit 63 to the matching
circuit 40b (see Figs. 4 and 5) of the antenna module 40.
[0054] Specifically, as illustrated in Fig. 14, the control circuit 63 sets the tuning voltage
V
tune1 use in the closed state, the tuning voltage V
tune2 use in the use state, and the tuning voltage V
tune3 used in the folded-back state for each channel of television broadcasting in the
form of the correspondence table. In addition, on the basis of the signal levels of
the detecting signals obtained from the sensors 71 and 72, the control circuit 63
selects one from among the tuning voltages V
tune1, V
tune2, and V
tune3 used in the closed state, the use state, and the folded-back state, respectively,
and transmits an indicating signal for indicating the selected tuning voltage to the
demodulation IC 62.
[0055] For example, when the user selects, for example, a channel CH1 by manipulating the
operating keys 122 and 123, the control circuit 63 determines whether the housings
are in the closed state, the use state, or the folded-back state on the basis of the
detecting signals received from the sensors 71 and 72. When the housings are in the
closed state, the control circuit 63 selects the tuning voltage V
tune1 (=1.4 V) used in the closed state corresponding to the channel CH1 and transmits
the indicating signal indicating the selected tuning voltage to the demodulation IC
62. When the housings are in the folded-back state, the control circuit 63 selects
the tuning voltage V
tune3 (=1.2 V) used in the folded-back state corresponding to the channel CH1, and when
the housings are in the use state, the control circuit 63 selects the tuning voltage
V
tune2 (=1.0 V) used in the use state corresponding to the channel CH1. The control circuit
63 then transmits the indicating signal indicating the selected tuning voltage to
the demodulation IC 62.
[0056] The demodulation IC 62 transmits the tuning voltage V
tune indicated by the indicating signal received from the control circuit 63 to the matching
circuit 40b of the antenna module 40.
[0057] Accordingly, the optimal tuning voltage according to the state (the closed state,
the use state, or the folded-back state) of the housings of the mobile phone 10 can
be supplied to the antenna module 40. In particular, in the closed state (see Fig.
10), the display surface 131 faces the first housing 120, and the liquid crystal display
unit 132 is not externally visible. However, in some cases, as illustrated in Fig.
10A, for example, a relatively smaller liquid crystal display unit 142 may be provided
to the other surface of the second housing 130 to receive and display the television
broadcasting and the like. Even in this case, the optimal tuning voltage needs to
be set according to the state of the first and second housings 120 and 130.
[0058] According to the embodiment, selecting the optimal tuning voltage according to the
states (the closed state, the use state, and the folded-back state) of the housings
illustrated in Figs. 10 to 12 is described. However, the states of the housings are
not limited thereto. For example, as illustrated in Fig. 15, the second housing 130
rotates in the horizontal direction with respect to the first housing 120 so that
the liquid crystal display unit 132 displays images of the television broadcasting
in a horizontally long state (hereinafter, referred to as horizontally long display
state). In this case, as sensing means for detecting the horizontally long display
state, for example, a second magnet 76 is provided to the second housing 130, and
a third sensor 73 is provided to a position of the first housing 120 corresponding
to the position of the second magnet 76 in the horizontally long display state illustrated
in Fig. 15, so as to determine the horizontally long display state according to the
output of the third sensor 73.
[0059] Accordingly, the mobile phone 110 according to the embodiment described above can
select the optimal tuning voltage according to the state of the housings and receive
the television broadcasting.
Another embodiment
[0060] In the aforementioned embodiments, the mobile phone receiving the television broadcasting
is described. However, the invention is not limited thereto, and the invention may
be applied to various types of mobile phones such as PDAs (personal digital assistants)
having a function of receiving television broadcasting.
[0061] The invention is applicable to mobile devices such as mobile phones having the function
of receiving television broadcasting.
[0062] It should be understood by those skilled in the art that various modifications, combinations,
sub-combinations and alterations may occur depending on design requirements and other
factors insofar as they are within the scope of the appended claims of the equivalents
thereof.