JPH11298997A - Portable communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a portable communication terminal that is easily made small, advantageous for cost reduction, and by which a high sound pressure level is obtained. SOLUTION: This portable communication terminal is formed by attaching a vibration element as a sound source to a housing 11, the generated sound is emitted to the outside of the housing 11, and a piezoelectric vibrator 12 is fixed to the wall face of the housing 11. An electrode opposed to a piezoelectric body is provided to make the piezoelectric vibrator 12 more mechanically by piezoelectric distortions caused when a voltage is applied between the electrodes. The terminal users the piezoelectric vibrator 12 of a mono morph, laminated, bimorph or multi-morph type that provides a large displacement output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable communication terminal such as a portable telephone or a receiver capable of making a call without a cord by indoor radio, and more particularly to a piezoelectric vibrator capable of obtaining a large output as a sound source and using the same as a housing. The present invention relates to a portable communication terminal attached to a personal computer.

[0002]

2. Description of the Related Art A piezoelectric acoustic device having a structure as shown in FIGS. 11 and 12, for example, has been mainly used as a receiver of a conventional portable communication terminal. That is, the piezoelectric element 6 is housed in a tray-shaped case 1 having a step 2 at an intermediate portion of an inner peripheral wall, and a peripheral portion of the diaphragm 7 is supported by the step 2 and a silicone adhesive 5 (see FIG. 12). Then, the lead wires 9 and 10 are drawn out of the case 1 from recesses formed in the peripheral wall of the case 1.

Further, a damper is provided on the upper wall of the case 1 to adjust the sound pressure-frequency characteristics of the sound generated from the piezoelectric acoustic device. For example, when a piezoelectric element 6 having a diameter of about 20φ is used, a through hole 3 having a diameter of about 1 to 2φ is provided in the center of the upper surface of the case 1, and a mesh 4 of about # 380 made of Tetron or the like is provided to form a damper. I have. With this damper, the sound pressure-frequency characteristic is adjusted so that a required sound pressure level is obtained in a predetermined sound range. other,
There is a case where a large number of small holes are opened without using the mesh 4 as described above, and the small holes are used as dampers.

Such a piezoelectric acoustic device is attached to a portable communication terminal such as a portable telephone or a receiver as shown in FIG. That is, the case 1 in which the piezoelectric element 6 is housed is applied with the opening side of the case 11 facing the inner surface of the housing 31 of a sounding device such as a mobile phone or a cordless horn. Is fixed with a double-sided adhesive sheet or the like via a bush made of an elastic material. Further, the lead wires 9, 10 are connected to the housing 31.
It is connected to a printed circuit board (not shown) housed inside, and is connected to the circuit of the portable communication terminal.

In the above-described piezoelectric acoustic device, a bending displacement type unimorph type or bimorph type is used as the piezoelectric element 6. For example, FIGS. 11 and 12 show a bending-displacement unimorph type. The piezoelectric element 6 is formed by forming a piezoelectric film 8 on one surface of a vibration plate 7 and soldering lead wires 9 and 10 to electrodes provided on the surfaces of the vibration plate 7 and the piezoelectric film 8, respectively.

[0006]

In the above-described piezoelectric acoustic device, a piezoelectric element which cannot have a large output, such as a unimorph type or bimorph type piezoelectric element, is used. Case 1 is required. Therefore, it is necessary to store the piezoelectric element 6 in the case 1 and attach the case 1 to the housing 31 of a portable communication terminal such as a mobile phone or a cordless phone.

However, since the case 11 is provided, it is difficult to reduce the size. Also, since the number of parts is large, the production cost of the parts is high. In particular, the case 1 is a molded plastic article, and the incineration cost for the mold cost is large. Moreover, since the assembly is complicated, the number of assembly steps is large. Therefore, the portable communication terminal incorporating the piezoelectric acoustic device as described above has a problem that it is difficult to reduce the size and the manufacturing cost. The present invention
In view of the problems of the conventional portable communication terminal using the piezoelectric acoustic device as described above, there is provided a portable communication terminal that can be easily reduced in size, is advantageous in reducing costs, and can obtain a high sound pressure level. The purpose is to:

[0008]

According to the present invention, in order to achieve the above object, a monomorph type, laminated type, bimorph type or multimorph type piezoelectric vibrator 1 is used as a sound source.
2, the piezoelectric vibrating body 12 is fixed to the housing 11 of the portable communication terminal. Thereby, the housing 11 of the portable communication terminal itself can be used as an acoustic box, and a portable communication terminal capable of obtaining a higher sound pressure level by the piezoelectric vibrator 12 can be obtained.

That is, in the portable communication terminal according to the present invention, a vibration element is attached to the housing 11 as a sound source.
The generated sound is emitted to the outside of the housing 11, and a monomorph type, a laminated type, a bimorph type or a multimorph type piezoelectric vibrator 1 is provided on a wall surface of the housing 11.
2 is fixed. The piezoelectric vibrating body 12 is an element that performs mechanical movement by piezoelectric distortion generated when an opposing electrode is provided on a piezoelectric body and a voltage is applied between the electrodes. Since the piezoelectric vibrator 12 has an extremely fast response speed, it can vibrate by applying an audio signal and emit sound.

There are two types of piezoelectric vibrators: a linear displacement type that utilizes deformation in the surface direction, and a bending displacement type that utilizes bending which is a displacement in a direction perpendicular to the surface. The stacked type is a linear displacement type in which a plurality of piezoelectric bodies are stacked. The bimorph type and the multimorph type are bending displacement types in which two or more piezoelectric bodies are bonded. Since these laminated, bimorph or multimorph type piezoelectric vibrators have two or more piezoelectric bodies, a large output is obtained and a high sound pressure level is obtained.

By fixing the piezoelectric vibrator 12 having such a large output to the inner surface of the housing 11 of the portable communication terminal, it is possible to use the housing 11 of the portable communication terminal itself as an acoustic box and emit sound. . Also,
An earpiece 15 is provided in the housing 11 of the portable communication terminal, and a user puts his / her ear on the earpiece 15 to receive a call when the portable communication terminal is used. However, at this time, the vibration of the earpiece 15 may be suppressed. In this regard, the piezoelectric vibrating body 12 is fixed to the inner wall of the wall of the housing 11 where the earpiece 15 is provided, or the other wall facing the wall of the housing 11 where the earpiece 15 is provided. By fixing the piezoelectric vibrating body 12 to the inner wall of the device, stable sound generation is possible without obstructing the vibration by the piezoelectric vibrating body 12. Further, by providing an appropriate sound emission hole 16 in the ear cover 15 of the housing 11, sound can be efficiently heard without being disturbed by ambient noise. Further, by providing the sound emitting hole 16 with a braking means for braking the sound emitted to the outside, it becomes possible to adjust the frequency-sound pressure level characteristics.

[0012]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings.
FIG. 1 is a partially longitudinal side view showing an example of a portable communication terminal according to the present invention, in which the left side is the upper side and the lower side is the front side.

The housing 11 is made of a resin molded body, and is provided with an antenna 13 at an upper portion thereof, which can be pulled out upward. Housing 11
A circuit board 20 to which a liquid crystal display for visually displaying necessary information is attached is built in, and the circuit board 20 constitutes an electronic circuit required as a portable communication terminal. At a position near the upper end of the front surface of the housing 11, there is provided a see-through window 14 through which a display unit such as the liquid crystal display can be visually recognized. Below the see-through window 14, a key switch 17 is provided for a user to input operation information and the like necessary for the electronic circuit. Below the key switch 17, a microphone 19 for converting a user's voice into an electric signal is provided. The microphone 19 obtains sound from outside the housing 11 and converts the sound into an electronic signal. The microphone 19 is soundproofed against the internal space of the housing 11 so as not to receive the sound inside the housing 11. Above the front surface of the housing 11, an earpiece 15 is provided for the user to listen to the sound by putting his / her ear, and in the illustrated example, the earpiece 15 is provided with a sound emission hole 16.
A mesh may be attached to the sound emitting hole 16 as braking means for adjusting the frequency-sound pressure level characteristic, or a large number of small holes may be provided. Further, a waterproof sheet or a dust-proof sheet may be attached to the sound emission hole 16. A battery 18 for driving a circuit formed on the circuit board 20 is detachably attached to a lower rear portion of the housing 11. In FIG. 1, a solid line indicates a state where the battery 18 is attached, and a two-dot chain line indicates a state where the battery 18 is detached. The state is shown. The lower portion of the rear surface of the housing 11 to which the battery 18 is attached has flat inner and outer surfaces.

In the example shown in FIG. 1, the piezoelectric vibrator 1 is provided on a flat inner surface at the lower back of the housing 11 on which the battery 18 is mounted.
2 is fixed. The inner surface at the lower rear portion of the housing 11 to which the battery 18 is attached is the widest flat portion of the housing 11, and a relatively large piezoelectric vibrating body 12 can be attached here.

The piezoelectric vibrator 12 is mounted on the inner wall of the housing 12.
Can be fixed by any means such as bonding with an adhesive or bonding via a double-sided adhesive sheet. Thus, the vibration of the piezoelectric vibrating body 12 is transmitted to the housing 11, resonates inside the housing 11, and the sound is emitted from the entire housing 11. By appropriately selecting the thickness of the entire housing 11 and the size, shape, and number of the sound emission holes 16 of the earpiece 15 or the roughness of a mesh attached thereto, the earpiece 15 is moved from the housing 11 to the housing 11. Can be adjusted so that the frequency-sound pressure level characteristic of the sound emitted to the outside becomes appropriate. Specifically, adjustment is performed so that a sound of 300 Hz to 3.4 KHz is emitted at a flat sound pressure level. Sound release hole 1 in earpiece 15
6 is easy to adjust the frequency-sound pressure level characteristics as described above, but if no sound emission hole 16 is provided, there is an advantage that the waterproofness is improved.

When the earpiece 15 is used as an earphone with the user's ear in contact with the earpiece 15, the piezoelectric vibrating body 1 is used so that the sound pressure level of the sound emitted from the earpiece 15 is not excessive.
2 is controlled. In addition, since a piezoelectric vibrator capable of obtaining a large displacement output is used, by changing the conditions for applying voltage to the piezoelectric vibrator 12, the piezoelectric vibrator can be used as a speaker for listening to sound while the ear is away from the earpiece 15. Is also possible.

As described above, the microphone 19 is
Since the sound is prevented from receiving the sound inside the housing 11, the sound generated by the vibration of the piezoelectric vibrating body 12 is not received. As described above, the piezoelectric vibrator 1
By attaching 2 to the rear wall side of the housing 11,
Even when the user of the portable communication terminal touches the ear cover 15 of the housing 11 with the ear or the like, the piezoelectric vibrating body 12 can vibrate without being affected and generate sound. In particular, the part to which the battery 18 is attached has a double wall formed by the relatively thick battery 18 in addition to the wall of the housing 11 in a normal use state. Almost no influence, stable vibration and sound can be generated in all use conditions.

FIG. 2 is a partially longitudinal side view showing another example of the portable communication terminal according to the present invention. In this example, the piezoelectric vibrating body 12 is attached to the inner wall on the back surface of the housing 11 opposite to the front surface portion where the ear cover 15 is provided.
This position is narrower than the inner surface of the portion where the battery 18 is attached, but is close to the earpiece 15, so that a high output sound pressure level can be obtained with the piezoelectric vibrator 12 having a small output.
Further, the upper rear side of the housing 11 is a portion where the user of the portable communication terminal device hardly touches the hand, and the piezoelectric vibrator 12 can vibrate without being affected by the outside, and can generate sound. Of course, the upper rear side of the housing 11 is not touched by the user of the portable communication terminal.

FIG. 3 is a partially longitudinal side view showing another example of the portable communication terminal according to the present invention. In this example, 12 is attached to the inner wall of the upper front portion of the housing 11 provided with the earpiece 15. Although this position is narrower than the mounting surface of the battery 18 described above, the inner wall of the earpiece 15 is suitable for providing a small, large-output piezoelectric vibrator.

As described above, the piezoelectric vibrating body 12 is an element which is provided with an electrode facing the piezoelectric body and performs a mechanical movement by piezoelectric strain generated when a voltage is applied between the electrodes. Piezoelectric vibrators include a linear displacement type using in-plane displacement, that is, deformation in a plane direction, and a bending displacement type using out-of-plane displacement, that is, bending that is displacement in a direction perpendicular to the plane. The former includes a single-plate type made up of a single-layered piezoelectric body and a stacked type made up of a plurality of piezoelectric bodies. The latter include a monomorph type consisting of a single-layer piezoelectric body, a unimorph type combining a piezoelectric body and an elastic plate one by one, a bimorph type sandwiching an elastic plate between two piezoelectric bodies or two piezoelectric bodies, There is a multimorph type in which a piezoelectric body is bonded.

In the present invention, a piezoelectric vibrator of a monomorph type, a laminated type, a bimorph type, a multimorph type, or the like which can obtain a large displacement output is used. The opposing electrodes of the piezoelectric vibrator 12 are connected to a drive circuit formed on the circuit board 20. Since the response speed of the piezoelectric vibrating body 12 is extremely fast, the piezoelectric vibrating body 12 can vibrate by applying a voice signal and emit voice.

FIG. 4 is a conceptual diagram showing the basic structure of a monomorph type piezoelectric vibrator. Lithium niobate single crystal 14
Monomorph type piezoelectric body 3 composed of a 0 ° rotating Y plate or the like
A pair of electrodes 32 made of a conductive film are provided on the upper and lower surfaces 1 (the electrodes on one end face are hidden behind the piezoelectric body 31 and cannot be seen). In the piezoelectric body 31, the domain-inverted layer grows from the + plane side by heat-treating the single-domain crystal plate just below the Curie point, and the growth stops at almost the center of the plate thickness. As shown by the arrow in FIG. 5, the piezoelectric body 3 is separated from the center of the thickness of the piezoelectric body 31 shown by the broken line in FIG.
Displacement occurs in directions facing each other at an angle of about 45 ° with respect to the first main surface. According to this principle, the pair of electrodes 3
When a voltage of an audio signal is applied during the period 2, bending deformation occurs according to the principle of a serial drive type bimorph. Sound is generated using this deformation.

FIGS. 5A and 5B are perspective views showing specific examples of a monomorph type piezoelectric vibrator. FIG.
The piezoelectric vibrator shown in (a) is provided with a through hole extending from one main surface of the piezoelectric body 31 to the other main surface, and connects an electrode on the lower surface side of the piezoelectric body 31 through a conductor provided in the through hole. Piezoelectric body 31
Are connected to a lead-out electrode 36 on the upper surface side, and lead wires 35 and 34 are connected to the lead-out electrode 36 and the electrode 32 on the upper surface side, respectively.

The piezoelectric vibrator shown in FIG. 5B is provided with a connection electrode 37 extending from one main surface of the piezoelectric body 31 to the other main surface on a part of the peripheral surface of the piezoelectric body 31. An electrode on the lower surface side of the piezoelectric body 31 is connected to an extraction electrode 36 on the upper surface side of the piezoelectric body 31 via an electrode 37, and the extraction electrode 36 and the piezoelectric body 3 are connected.
Lead wires 35 and 34 respectively with the electrode 31 on the upper surface side of
Are connected.

FIG. 6 is a conceptual diagram showing the basic structure of a laminated piezoelectric vibrator. A plurality of piezoelectric bodies 31 are stacked via a conductor layer 33, and a pair of external electrodes 32 made of a conductive film are provided on the end faces of the piezoelectric bodies 31 at both ends (the external electrodes on one end face are shaded by the piezoelectric bodies 31). Invisible). The external electrodes 32 and the conductor layers 33 are alternately connected every other one, and are connected to a pair of terminals 34 and 35. By applying an audio signal to the terminals 34 and 35, each piezoelectric body 31 is displaced in the stacking direction.
A displacement in the plane direction as shown by an arrow in FIG. Sound is generated using this displacement. Therefore,
This stacked actuator is used by fixing the upper surface or the lower surface to the inner surface of the housing 11 in FIG.

FIG. 7 is a conceptual diagram showing the basic structure of a laminated piezoelectric vibrator. The main surface of the two piezoelectric members 31 is the conductor layer 3
3, a pair of external electrodes 32 made of a conductive film are provided on the other main surface of the piezoelectric body 31 (the external electrodes on one end face are invisible behind the piezoelectric body 31). Have been. FIG. 7 (a) connects external electrodes 32 and conductor layers 33 on both surfaces to terminals 34 and 35, respectively, and applies a drive voltage to these terminals 34 and 35, which is a so-called parallel type. On the other hand, FIG. 7B shows a so-called series type in which drive voltages are applied to the external electrodes 32 on both surfaces to terminals 34 and 35, respectively. In any case, when an audio signal is applied to the terminals 34 and 35, a displacement occurs in a direction orthogonal to the plane indicated by the arrow in FIG. Sound is generated using this displacement. Therefore, this bimorph-type actuator is used by fixing the upper or lower surface to the inner surface of the housing 11 in FIG.

Although not shown, the basic concept of the multi-morph type piezoelectric vibrating body is not different from that of the multi-morph type piezoelectric vibrating body, since only four or more piezoelectric bodies 31 are bonded. That is, the main surfaces of four or more piezoelectric bodies are bonded via a conductor layer, and a pair of external electrodes made of a conductive film are provided on the other main surface of the endmost piezoelectric body.

FIG. 8 shows a specific example of a bimorph type piezoelectric vibrating body having a parallel type structure. One main surface of the two disc-shaped piezoelectric bodies 31 is bonded via a conductor layer 33. A notch-shaped concave portion 38 is provided in a peripheral portion of one piezoelectric body 31, and a part of the conductor layer 33 is exposed as a connecting portion 36 at this portion. A pair of external electrodes 32 are formed on the other main surface of the piezoelectric body 31, that is, on the upper and lower surfaces of the two piezoelectric bodies 31 in FIG.
Are connected to each other via a connection conductor 37 provided on the peripheral surface of the piezoelectric body 31. The lead wires as the terminals 34 and 35 are connected to the external electrode 32 and a part of the connection portion 36 of the conductor layer 33.

FIG. 9 shows a specific example of a multi-morph piezoelectric vibrating body having a parallel structure. One main surface of each of the four disc-shaped piezoelectric members 31 is sequentially bonded via a conductor layer 33. The uppermost piezoelectric body 3 in FIG.
A notch-shaped concave portion 38 is provided in the periphery of 1, and a part of the conductor layer 33 is exposed as a connecting portion 36 at this portion.
The conductor layer 33 between the piezoelectric bodies 31 is led out to the peripheral surface of the piezoelectric body 31 at a portion corresponding to the connection portion 36,
This lead-out portion is connected via a connection conductor 39.
A pair of external electrodes 32 are formed on the other main surface of the piezoelectric members 31 at both ends, that is, on the upper surface and the lower surface of the uppermost and lowermost piezoelectric members 31 in FIG.
1 are connected to each other via a connection conductor 37 provided on the peripheral surface of the first. The lead wires as the terminals 34 and 35 are connected to a connection portion 36 that is connected to the external electrode 32 and the conductor layer 33. Although the piezoelectric vibrator shown in FIGS. 8 and 9 is circular, the shape is not limited. Rectangle, ellipse and other shapes can be employed as needed.

FIG. 10 shows frequency-sound pressure level characteristics of a portable communication terminal using a bending displacement type bimorph type piezoelectric vibrator and a portable communication terminal using a linear displacement type single plate type piezoelectric vibrator. It is shown. The same shape was used for both housings, and a predetermined surface of the piezoelectric vibrator was attached to the same location. The solid line is for the former mobile communication terminal,
The broken line is for the latter mobile communication terminal. In the mobile communication terminal using the bending displacement type bimorph type piezoelectric vibrator, a peak is observed at around 4.5 KHz, but the whole is compared with the mobile communication terminal using the linear displacement type single plate type piezoelectric vibrator. A high sound pressure level is obtained.

[0031]

As described above, in the portable communication terminal according to the present invention, the piezoelectric vibrator 12 having a large output as a sound source.
By fixing the piezoelectric vibrating body 12 to the inner wall of the housing 11 of the portable communication terminal, the housing 11 itself of the portable communication terminal is used as an acoustic box,
A high sound pressure level can be obtained. This facilitates attachment of the sound source to the housing 11 and facilitates assembly of the portable communication terminal.

[Brief description of the drawings]

FIG. 1 is a partially longitudinal side view showing an example of a portable communication terminal according to the present invention.

FIG. 2 is a partially longitudinal side view showing another example of the portable communication terminal according to the present invention.

FIG. 3 is a partially longitudinal side view showing another example of the portable communication terminal according to the present invention.

FIG. 4 is a conceptual diagram showing a basic structure of a monomorph type piezoelectric vibrator.

FIG. 5 is a conceptual diagram showing an example of a specific structure of a monomorph type piezoelectric vibrator.

FIG. 6 is a conceptual diagram showing a basic structure of a laminated piezoelectric vibrator.

FIG. 7 is a conceptual diagram showing a basic structure of a bimorph type piezoelectric vibrator.

FIG. 8 is a conceptual diagram showing an example of a specific structure of a bimorph type piezoelectric vibrator.

FIG. 9 is a conceptual diagram showing an example of a specific structure of a multimorph type piezoelectric vibrator.

FIG. 10 shows an example of frequency-sound pressure level characteristics of a portable communication terminal using a flexural displacement type bimorph type piezoelectric vibrator and a portable communication terminal using a linear displacement type single plate type piezoelectric vibrator. It is a graph.

FIG. 11 is an exploded perspective view showing an example of a piezoelectric acoustic device used in a conventional portable communication terminal as viewed from the bottom.

FIG. 12 is a longitudinal sectional side view showing a state where the piezoelectric acoustic device is attached to a housing of a portable communication terminal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Housing 12 Piezoelectric vibrator 15 Housing earpiece 16 Sound emission hole of earpiece

Claims (6)

[Claims] A portable communication terminal for attaching a vibration element as a sound source to a housing (11) and emitting the generated sound to the outside of the housing (11).
A portable communication terminal characterized in that a monomorph type, laminated type, bimorph type or multimorph type piezoelectric vibrator (12) is fixed to the wall surface of 1). 2. The portable communication terminal according to claim 1, wherein the piezoelectric vibrator is fixed to an inner wall of a housing. 3. An ear cover (15) for applying a user's ear to the housing (11), and a piezoelectric vibration is applied to an inner wall of the wall provided with the ear cover (15) of the housing (11). 3. The portable communication terminal according to claim 1, wherein the body is fixed. 4. An ear cover (1) of said housing (11).
The portable communication terminal according to claim 2, wherein a piezoelectric vibrator (12) is fixed to an inner wall of the other wall facing the wall provided with (5). 5. A sound emission hole (16) in the earpiece (15).
The mobile communication terminal according to claim 3 or 4, wherein a mobile communication terminal is provided. 6. A sound output hole (16) of the earpiece (15).
6. The apparatus according to claim 5, further comprising a braking means for adjusting frequency-sound pressure level characteristics.