JP2003298454A - Mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To excellently keep the communication quality by reducing the interference among circuit components while making the profile of the enclosure low. <P>SOLUTION: A planar ground pattern 411 is formed on a printed circuit board 41 at a position opposed to a sub LCD unit 43, and a plurality of circuit components 412, 413 mutually requiring electromagnetic and thermal isolation are mounted apart from each other with the ground pattern 411 inbetween. Further, a shield case 42 having both a support function of the sub LCD unit 43 and a shield function of the circuit components 412, 413 is fitted to the printed circuit board 41, and the shield case 42 electromagnetically separates the circuit components 412, 413. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to mobile communication terminals such as DAs (Personal Digital Assistants).

[0002]

2. Description of the Related Art For mobile communication terminals represented by mobile phones, downsizing and weight reduction are important issues. In particular, a so-called folding type mobile communication terminal in which the first housing and the second housing are openably and closably connected using a hinge mechanism has a large dimension in the thickness direction of the terminal when folded, There is a demand for thinner first and second casings.

On the other hand, in recent mobile communication terminals, in addition to the main display installed on the front surface of the housing, a sub-display is installed on the back surface of the housing. If a sub-display is installed in addition to the main display, the user can check the display information regardless of the orientation of the mobile communication terminal. In particular, in the folding mobile communication terminal, it is not necessary to open the housing each time to check the time, the operating state of the terminal, etc., and the convenience for the user is improved.

[0004]

However, in general, the main display and the sub-display are provided back to back in the same housing. Therefore, the thickness of the housing is further increased, the portability is impaired, and the degree of freedom in design is reduced.

On the other hand, in order to reduce the thickness of the housing, it has been considered that circuit components such as integrated circuits are concentrated and mounted at specific positions on the printed wiring board. However, if the circuit components are intensively mounted at a specific position, the mounting density of the circuit components is increased, and electromagnetic or thermal interference between the circuit components is likely to occur, resulting in deterioration of communication quality.

The present invention has been made in view of the above circumstances, and an object thereof is to reduce the interference between circuit components while maintaining a good communication quality while reducing the thickness of the housing. It is to provide a mobile communication terminal capable of performing the above.

[0007]

In order to achieve the above object, the present invention resides in a mobile communication terminal in which a printed wiring board on which circuit components are mounted and a display unit are housed in a housing in an overlapping manner. A planar ground pattern is formed on a portion of the printed wiring board that faces the display unit, and the first and second portions of the printed wiring board that are separated from each other are isolated from each other. It is configured such that the first and second circuit components that need to be installed are separately mounted. For example, as the first and second circuit components, circuit components that need to be electromagnetically separated from each other and circuit components that need to be thermally separated from each other are applied.

Therefore, according to the present invention, the ground pattern is formed on the portion of the printed wiring board which faces the display unit, and the circuit components are mounted in the peripheral portion in a dispersed manner. Therefore, compared to the case where the circuit components are mounted on the entire surface of the printed wiring board, the distance between the printed wiring board and the display unit can be made closer, and the thickness of the housing can be reduced correspondingly to improve portability and design. It is possible to secure the degree of freedom.

Further, the first and second circuit components which need to be isolated from each other are mounted with the ground pattern separated. Therefore, not only the first and second circuit components are separated from each other in terms of distance, but also a good isolation performance can be obtained due to the shield effect of the ground pattern.

For example, when circuit components which require mutual electromagnetic isolation are mounted as the first and second circuit components, they are provided on the opposite surface of the printed wiring board or on the inner layer of the multilayer printed wiring board. The noise generated in the signal wiring pattern is absorbed by the ground pattern. That is, the ground pattern exerts an electromagnetic shielding effect, and electromagnetic isolation performance can be kept high. Further, when the circuit components that require mutual thermal isolation are mounted as the first and second circuit components, the ground pattern functions as a heat radiating member and a heat conductive material, so that the heat generated by the circuit components is locally generated. It becomes difficult to concentrate the heat, and thereby the thermal characteristics of the first and second circuit components can be improved.

Further, according to the present invention, a shield case having a function of shielding at least one of the first and second circuit components and a function of holding the display is provided between the printed wiring board and the display unit. Also features. According to this structure, the first and second circuit components are electromagnetically separated more effectively by the shielding effect of the shield case, and as a result, the isolation characteristic between the circuit components is further improved. You can Moreover, since the shield case also functions as a holder for the display unit, the size of the housing in the thickness direction can be reduced as compared with the case where a dedicated holder is provided.

Further, according to the present invention, a printed wiring board on which a heat generating circuit component is mounted and a display unit are housed in a housing in an overlapping manner, and a receiving speaker is arranged in the vicinity of the heat generating circuit component. In a communication terminal, a planar ground pattern is formed on a portion of the printed wiring board facing the display unit, and the heat generating circuit component is mounted on the printed wiring board at a position close to the ground pattern. It is also characterized by doing.

With this structure, the heat generated by the heat generating circuit component is transmitted to the planar ground pattern and is radiated from this ground pattern. For this reason, it is possible to suppress the temperature rise in the vicinity of the receiving speaker, thereby reducing the discomfort of the user.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows an external appearance of a foldable mobile phone which is a first embodiment of a mobile communication terminal according to the present invention when opened.
(A) is the front view, (b) is a side view, (c) is a rear view.

This foldable mobile phone has a lower housing 1
And the upper housing 2 are rotatably connected via a hinge mechanism 3. The key input section 1 is provided on the front surface of the lower housing 1.
1 and a speaker 12 for transmission, and a battery storage portion is provided on the back surface. On the other hand, on the front surface of the upper housing 2, a main display 21 composed of an LCD (Liquid Crystal Devise) and a receiving speaker 22 are arranged, and on the rear surface thereof, a sub display 24 also composed of an LCD is arranged. Reference numeral 23 denotes an antenna, which is housed in an antenna housing portion 25 provided on the back cover 2b so as to be movable back and forth.

By the way, the upper housing 2 is constructed as follows. 2 is an exploded perspective view showing the structure, and FIG. 5 is a transverse sectional view. That is, the front cover 2a and the back cover 2b
The display unit 4 is housed in a housing composed of. The display unit 4 is an integrated unit in which the printed wiring board 41 is sandwiched between the main display 21 and the sub-display 24.

First of all, the main display 21 is
As shown in FIG. 5, the main LCD unit 210 is an LCD
The main LCD holder 211 holding the main LCD unit 210 is fixed to a shield case 214, and the shield case 214 is attached to one surface of the printed wiring board 41. Incidentally, 212 is a transparent window for the main display 21 provided on the front cover 2a, and 213 is the printed wiring board 41.
It is a circuit component mounted on one surface of the.

On the other hand, the sub-display 24 is constructed as follows. FIG. 3 is an exploded perspective view showing the structure.
That is, the sub display 24 includes the sub LCD unit 43 and the shield case 42. The sub-LCD unit 43, as shown in FIG.
A flexible cable 432 is connected to 31 and a light guide 433 is attached to the back surface of the sub LCD 431. The light guide 433 is attached to the sub LCD 431 by using, for example, a double-sided tape.

The shield case 42 is a printed wiring board 41.
It has both the function of shielding the circuit components 412 and 413 mounted on the other surface of the above and the function of holding the sub LCD unit 43, and is composed of a frame-shaped member with a hollowed central portion. The sub LCD unit 43 is fixed to the hollowed central portion 421 of the shield case 42. As shown in FIG. 6, the sub LCD unit 43 is fixed by fitting a plurality of protrusions 434 provided on the outer edge of the sub LCD unit 43 into a plurality of grooves 422 provided on the inner edge of the central portion 421 of the shield case 42. It is done by combining.

By the way, in the central portion of the surface of the printed wiring board 41 on which the sub-display 24 is attached, as shown in FIG.
A solid ground pattern 411 is formed as shown in FIG. The ground pattern 411 is provided at a position facing the sub LCD unit 43, and its shape and size are set so as to correspond to the shape of the sub LCD unit 43 and be slightly larger than it. The ground pattern may have a grid pattern or a stripe pattern, and in short, may be any planar ground pattern.

Further, a plurality of circuit components are mounted on the printed wiring board 41 in the peripheral portion of the ground pattern 411 as shown in FIG. 7, for example. The layout of these circuit components is such that the first and second circuits need to be electromagnetically and thermally separated from each other.
Circuit parts 412 and 413 of the above-mentioned ground pattern 411.
Are set to be separated from each other. For example, the circuit component including the high frequency power amplifier is arranged on one side as the first circuit component 412, while the circuit component forming the high frequency receiving circuit including the reception intermediate period amplifier and the like is the second circuit component 413. Are arranged on the other side, respectively.

Further, a plurality of circuit components mounted on the printed wiring board 41 are shielded by the shield case 4 for each group.
Separated by two partitions. FIG. 7 shows the configuration thereof, and the two-dot chain line in the figure indicates the position of the partition wall of the shield case 42.

With such a structure, only the ground pattern 411 is formed on the printed wiring board 41 at a position facing the sub LCD unit 43, and the circuit components are dispersedly mounted on the peripheral portion thereof. Therefore, the printed wiring board 41
As compared with the case where the circuit components are mounted on the entire surface of the printed wiring board 41, the arrangement interval between the printed wiring board 41 and the sub display 42 can be made closer. Further, the central portion 4 of the shield case 42
The sub-LCD unit 43 is held by hollowing out 21 and fitting the sub-LCD unit 43 there. Therefore, compared with the case where the holding member of the sub LCD unit 43 and the shield case are provided separately,
The dimension in the thickness direction can be suppressed. Therefore, due to these synergistic effects, according to the present embodiment, it is possible to reduce the thickness of the upper housing 2 and sufficiently secure portability and design freedom.

Further, among the circuit components mounted on the peripheral portion of the printed wiring board 41, the first one is required to be electromagnetically and thermally isolated from each other like the relationship between the high frequency power amplifier and the reception intermediate frequency amplifier. And second circuit components 412 and 413
Are mounted at positions separated by the ground pattern 411. Furthermore, these first and second circuit components 41
The partition wall of the shield case 42 electromagnetically separates 2, 413 electromagnetically. Therefore, the first and second
The circuit components 412 and 413 are separated from each other in terms of distance, and good isolation performance can be maintained due to the shield effect of the ground pattern 411 and the partition wall of the shield case 42.

For example, the noise generated in the circuit components such as the high frequency power amplifier is separated into the distance and is blocked by the partition wall of the shield case 42, so that the noise is transmitted to the circuit components of the receiving circuit system. It becomes difficult to communicate.

Signal wiring patterns 414 and 416 are provided on the inner layer of the multilayer printed wiring board as shown in FIG. 8, and noise is generated from these signal wiring patterns 414 and 416. However, the noise generated from this signal wiring pattern is effectively absorbed by the ground pattern 411 having a large area. Therefore, the peripheral circuit parts 41
The effect of the noise on 2,413 is reduced.

On the other hand, most of the heat generated by the high frequency power amplifier is transmitted to the ground pattern 411 having a large area provided in the vicinity thereof and is radiated from the ground pattern 411. Therefore, the problem that the heat generated by the high-frequency power amplifier is accumulated in the peripheral portion and locally becomes high is avoided.
As a result, not only the high-frequency power amplifier itself but also other circuit components around it are less affected.

Also, the discomfort caused by the heat generated by the user is reduced. That is, as shown in FIGS. 1A and 2, the upper housing 2 is provided with a speaker 22 for receiving a voice, and a user talks with his / her ear in contact with or close to the speaker 22. To do. For this reason, the heat generated from the circuit component 412 such as the high frequency power amplifier is transmitted to the user's ear during the call, which gives the user discomfort. However, in the present embodiment, the heat generated by the heat generating circuit component 412 is transmitted to the planar ground pattern 411 and is radiated from this ground pattern 411. Therefore, the temperature rise around the speaker 22 can be suppressed, and the discomfort of the user can be reduced.

Further, in this embodiment, as described above, the plurality of protrusions 434 provided on the outer edge of the sub LCD unit 43 are provided in the plurality of grooves 422 provided on the inner edge of the central portion 421 of the shield case 42. By mating,
The sub LCD unit 43 is fixed to the shield case 42. Therefore, the sub LCD unit 43 can be fixed easily, highly accurately, and stably, which makes it possible to maintain high reliability of the terminal and further improve assembly workability.

(Second Embodiment) In the second embodiment of the present invention, a recess is provided at a position facing the sub LCD unit of the printed wiring board, and a planar ground pattern is formed on the bottom surface of the recess. It is configured such that circuit components requiring electromagnetic and thermal isolation are mounted separately on the printed wiring board at positions separated from the recess.

FIG. 9 is a cross-sectional view showing the structure of the upper casing of a foldable portable telephone which is a second embodiment of the mobile communication terminal according to the present invention. In the figure, the same parts as those in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

Sub-display 2 of printed wiring board 41 '
A concave portion 417 is provided in the central portion on the surface to which 4 is attached. The recess 417 is formed in the sub LCD unit 4 described above.
It is provided at a position facing 3 and its shape and size are set so as to correspond to the shape of the sub LCD unit 43 and be slightly larger than that. Then, this recess 41
A solid ground pattern 411 is formed on the bottom surface of 7. The ground pattern may have a grid pattern or a stripe pattern, and in short, may be any planar ground pattern.

A plurality of circuit components are mounted on the printed wiring board 41 'around the recess 417.
As shown in FIG. 7, the arrangement of these circuit components is such that the first and second circuit components 412 and 413, which need to be electromagnetically and thermally separated from each other, are formed on the bottom surface of the recess 417. It is set to be separated by 411.

A sub LCD is provided on the printed wiring board 41 '.
A shield case 42 'to which the unit 43 is fixed is attached. At this time, the bottom surface of the central portion of the shield case 42 'is positioned so as to contact the ground pattern 411 in the recess 417.

With such a structure, the height of the shield case 42 'in the state where the shield case 42' is attached to the printed wiring board 41 'is the same as that of the printed wiring board 41'.
It is lowered by an amount corresponding to the depth of the concave portion 417 provided in the. Therefore, the thickness of the back cover 2b 'of the upper housing 2 is further reduced, and as a result, the upper housing 2 can be made even thinner.

Also in the second embodiment, among the circuit components mounted on the peripheral portion of the printed wiring board 41 ', the transmission high-frequency power amplifier and the reception intermediate-frequency amplifier are electromagnetically related to each other. The circuit components 412 and 413, which are required to be thermally and thermally isolated, are mounted at positions separated by the ground pattern 411. Moreover, these circuit components 412 and 413 are electromagnetically separated by the partition wall of the shield case 42 '. Therefore, the circuit components 412 and 413 are separated from each other in terms of distance, and the ground pattern 411 and the shield case 42 'are also provided.
Due to the shielding effect of the partition wall, good isolation performance can be maintained.

(Other Embodiments) In each of the above embodiments, the ground pattern 411 is formed in the central portion of the printed wiring boards 41 and 41 'in correspondence with the position of the sub LCD unit.
Circuit parts 41 that need to be isolated from each other around their periphery
2, 413 is implemented.

However, in the mobile communication terminal, the sub-display is arranged in a direction orthogonal to the longitudinal direction of the upper casing.
In other words, some are installed sideways. In this case,
Depending on the orientation of the sub-display, for example, FIG.
As shown in FIG.
11 'is formed laterally, and a plurality of circuit components 412', 413 'which need to be isolated from each other are mounted with the ground pattern 411' interposed therebetween. Even in such a configuration, the housing is made thinner and the circuit components 412 ′, 41
It is possible to maintain the isolation performance between 3 '.

In the above embodiment, the foldable mobile phone has been described as an example, but the present invention can be applied to a mobile communication terminal of a type in which the first and second casings are slid by a sliding mechanism to open and close, Furthermore, the present invention can be applied to a straight type mobile communication terminal including one housing.

Other types of mobile communication terminals and their structures,
Regarding the installation position of the sub display and the formation position of the ground pattern corresponding to it, the shape and size of the ground pattern, the types of multiple circuit components that need to be isolated from each other and their placement positions, the structure of the shield case, etc. Various modifications can be implemented without departing from the scope of the present invention.

[0041]

As described above in detail, according to the present invention, there is provided a mobile communication terminal in which a printed wiring board on which circuit components are mounted and a display unit are housed in a housing in an overlapping manner. A planar ground pattern is formed on a portion of the substrate facing the display unit, and first and second portions of the printed wiring board, which are separated from each other, need isolation. The first and second circuit components are separately mounted.

Therefore, according to the present invention, it is possible to provide a mobile communication terminal capable of reducing interference between circuit components and maintaining good communication quality while reducing the thickness of the housing.

[Brief description of drawings]

FIG. 1 is an external view of a foldable mobile phone which is a first embodiment of a mobile communication terminal according to the present invention.
(A) is the front view, (b) is a side view, (c) is a rear view.

FIG. 2 is an exploded perspective view showing a configuration of an upper housing of the folding mobile phone shown in FIG.

FIG. 3 is an exploded perspective view showing a configuration of a sub display provided in the upper housing shown in FIG.

4 is a sub LCD of the sub display shown in FIG.
The disassembled perspective view which shows the structure of a unit.

5 is a cross-sectional view of an upper housing portion of the folding mobile phone shown in FIG.

FIG. 6 is an enlarged view showing a main part of the upper housing part shown in FIG.

7 is a plan view showing the configuration of a printed wiring board provided in the upper housing shown in FIG.

8 is a partial cross-sectional view showing the configuration of a printed wiring board provided in the upper housing shown in FIG.

FIG. 9 is a transverse cross-sectional view showing the configuration of the upper casing of a foldable mobile phone which is a second embodiment of the mobile communication terminal according to the present invention.

10 is a plan view showing the configuration of the printed wiring board shown in FIG.

FIG. 11 is a plan view showing the configuration of a printed wiring board according to another embodiment of the present invention.

[Explanation of Codes] 1 ... Lower housing 2 ... Upper housing 2a ... Front cover 2b ... Rear cover 3 ... Hinge mechanism 4 ... Display unit 11 ... Key input unit 12 ... Transmitting microphone 21 ... Main display 22 ... Reception Speaker 23 ... Antenna 24 ... Sub display 25 ... Antenna housing 41, 41 '... Printed wiring board 42, 42' ... Shield case 43 ... Sub LCD unit 210 ... Main LCD 211 ... LCD holder 212, 213 ... Transparent window 214 ... Shield cases 411, 411 ', 415 ... Ground patterns 213, 412, 412', 413, 413 '... Circuit parts 414, 416 ... Signal wiring pattern 417 ... Recessed portion 421 ... Hollowed-out central portion 422 ... Groove 431 ... Sub LCD 432 ... Flexible cable 433 ... Light guide 434 ... Protrusion

Continued front page    F-term (reference) 5E321 AA01 AA17 CC02 GG05                 5K011 AA03 AA13 AA15 JA01 KA05                 5K023 AA07 BB28 LL01

Claims (5)

[Claims] 1. A mobile communication terminal in which a printed wiring board on which circuit components are mounted and a display unit are housed in a housing in an overlapping manner, the portion facing the display unit on the printed wiring board. A planar ground pattern is formed on the printed wiring board, and the first and second circuit components, which need to be separated from each other, are separately mounted on the first and second portions of the printed wiring board that separate the ground pattern. A mobile communication terminal characterized by the above. 2. The mobile communication terminal according to claim 1, wherein the first and second circuit components are circuit components that need to be electromagnetically separated from each other. 3. The mobile communication terminal according to claim 1, wherein the first and second circuit components are circuit components that need to be thermally separated from each other. 4. A shield case having a function of shielding at least one of the first and second circuit components and a function of holding the display is provided between the printed wiring board and the display unit. The mobile communication terminal according to claim 1, wherein: 5. A mobile communication terminal in which a printed wiring board on which a heating circuit component is mounted and a display unit are housed in a casing in an overlapping manner, and a receiving speaker is arranged in the vicinity of the heating circuit component. And a planar ground pattern is formed on a portion of the printed wiring board facing the display unit, and the heating circuit component is mounted on a position of the printed wiring board in the vicinity of the ground pattern. A characteristic mobile communication terminal.