JPH10125163A - Key pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent radiation noises or reflection noises, reduce the number of part items, reduce packaging man-hours and cost, miniaturize a key pad section, and make it lightweight by forming it with a composite magnetic substance constituted of soft magnetic substance powder and an organic binder. SOLUTION: A portable telephone 1 is constituted of a key pad section 6, a housing 2, and a display 7. The key pad section 6 is formed with a composite magnetic substance constituted of soft magnetic substance powder using the metal magnetic substance powder having an oxide film on the surface and an organic binder. Both the key pad section 6 and the housing 2 are made of an electromagnetic wave interference preventing material kneaded and dispersed with magnetic powder in a resin, an elastomer having a good expansion characteristic is used for the resin, and flat powder is used for the magnetic powder. High-frequency radiation and reflection noises are prevented without impairing the good moldability of the resin and without causing secondary radiation, and no shield plate is required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a portable telephone, a PH
The present invention relates to a keypad used in an S, a transceiver, various electronic devices, and the like, and in particular, to a keypad used for the keypad and materials of the keypad and the housing.

[0002]

2. Description of the Related Art Conventionally, this kind of keypad has been used for portable telephones, PHSs, transceivers, various electronic devices and the like. For example, a keypad will be described by taking a portable wireless communication terminal as an example. First, the keypad of these portable wireless communication terminals is used together with a housing and is formed of resin. The resin-made keypad portion, the keypad portion, and the housing have been widely used because of their excellent moldability and light weight.

In recent years, the effect of electromagnetic waves has become a problem. Portable wireless communication terminals are no exception.

[0004] The effects of a portable radio communication terminal using a keypad have the following problems.

[0005] It is an effect on other electronic devices and the like.
The problem is particularly acute for medical devices. Electromagnetic waves emitted by mobile phones cause malfunctions of medical devices and abnormalities of pacemakers.

[0006] All of them are generally affected by electromagnetic waves used for communication, but electromagnetic waves generated from various devices mounted on the portable radio communication terminal, that is, radiation and reflection noise are minimized. In order to prevent generation and intrusion of electromagnetic waves, it is essential to shield the equipment used. For this reason, a shield plate is used in the wireless terminal.

However, the use of a shield plate in order to prevent the generation and invasion of electromagnetic properties has the disadvantage that the number of components increases and the cost increases.

[0008]

To solve the problem of the shield, as shown in FIG. 5, a keypad portion 6, a display 7, a metal shield plate 3, and a device 4 are provided inside a resin housing 2. In general, a shield plate 3 covers the entire mounting device 4 and a resin casing 2 covers the outside of the mounting device 4, thereby preventing noise inside and outside the above problem. Is quite possible. However, since the shield plate is installed close to the device, secondary radiation occurs due to reflection, or conducted noise becomes radiation noise using the shield plate as an antenna, and the portable wireless communication terminal itself malfunctions due to noise. And so on.

An object of the present invention is to prevent the radiation noise or reflection noise, eliminate the need for a shield plate, reduce the number of components, reduce the number of steps and cost for mounting, reduce the size and weight, and reduce the number of components inside and outside. An object of the present invention is to provide an inexpensive keypad used together with a housing that is sufficiently shielded.

[0010]

According to the present invention, the problem is solved by forming the keypad and the keypad and the housing with a material that does not transmit electromagnetic waves to the outside and does not reflect the electromagnetic waves inside. At this time, a material capable of preventing reflection and radiation noise is used for the portable radio communication device and the like currently used in the high frequency band for the key pad, the key pad and the housing, and various types of high speed and high frequency are used. An object of the present invention is to provide a keypad that absorbs not only noise generated from a device but also noise leaked from a high-frequency device installed therein.

The present invention is a keypad comprising a composite magnetic substance comprising a soft magnetic substance powder and an organic binder.

Further, the present invention is a keypad, wherein the keypad has a multilayer structure of the composite magnetic body and a conductor layer, and the conductor layer is not provided on an inner surface layer.

Further, the present invention is the above keypad, wherein the keypad is used together with a housing made of a composite magnetic material comprising a soft magnetic material powder and an organic binder.

Further, the present invention provides the key pad according to the present invention, characterized in that the key pad has a multilayer structure of the composite magnetic body and the conductor layer, and the inner surface layer is used together with a housing not provided with the conductor layer. is there.

Further, the present invention provides the above-mentioned keypad, wherein the soft magnetic powder comprises a metal magnetic powder having an oxide film on a surface thereof and has a surface resistance of 10 ³ Ω or more. It is.

The present invention also provides the above keypad, wherein the composite magnetic body has at least two magnetic resonances caused by anisotropic magnetic fields having different magnitudes from each other.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the keypad of the present invention will be described with reference to the drawings. The keypad of the present invention will be described using a mobile phone of a mobile wireless communication terminal as an example.

The keypad of the present invention is used, for example, in a mobile phone. As shown in FIG. 1, the mobile phone 1 includes a keypad portion 6 made of a composite magnetic material composed of a soft magnetic powder using a metal magnetic powder having an oxide film on its surface and an organic binder, and a housing 2. , Display 7, substrate 5 on which device 4 is mounted, and battery 8. Similarly, both the keypad portion 6 and the housing 2 are made of a material for preventing electromagnetic interference in which a magnetic powder is kneaded and dispersed in a resin. As the resin, an elastomer having good elasticity is used. As the magnetic powder, a flat powder is used. It is preferred that Also,
As the resin, a thermoplastic resin such as a polyester resin, a polyvinyl chloride resin, a polyvinyl butyral resin, a polyurethane resin, a celerol resin, a nitrile butajun rubber, or a polymer epoxy resin thereof, a phenol resin, an amide resin And thermosetting resins such as isid-based resins. As the magnetic powder, a composite magnetic material composed of a soft magnetic powder using a metal magnetic powder having an oxide film on the surface and an organic binder was used.

Table 1 shows the soft magnetic powder and the organic binder used for the keypad portion of the mobile phone, or the keypad portion and the housing of the keypad of the present invention.

[0020]

The soft magnetic material powder is composed of nitrogen having a partial pressure of oxygen of 20%.
Vapor phase oxidation is performed in an oxygen mixed gas atmosphere to form an oxide film on the surface. These are heat-kneaded and pressure-formed to obtain a molded body. As a result of measuring the surface resistance of this composite magnetic material, 1 × 1
It was 0 ⁶ Ω. When various surface resistances of the composite magnetic material were examined, a relationship between the surface resistance, the transmission attenuation level, and the coupling level as shown in FIG. 4 was obtained. From FIG. 4, it was found that the surface resistance of the composite magnetic material should be not less than 10 ³ Ω in order to prevent the electromagnetic wave from transmitting to the outside and not reflecting the inside. A shows a graph of the coupling level, and B shows a graph of the transmission attenuation level.

FIG. 2 shows the results of measuring the μ-f characteristics of the composite magnetic material. The solid line shows the μ characteristic after annealing, and the broken line shows the μ characteristic before annealing. In the composite magnetic material before the annealing treatment, as shown in FIG. 2, a peak of μ ″ accompanying magnetic resonance appears, which indicates that magnetic resonance occurs at two places.
μ ″ shows a high value in a wide range, and μ ′ also shows a large value at a high frequency.

(Embodiment 1) A keypad portion 6 having an average thickness of 0.5 mm was formed from the composite magnetic material. The keypad unit 6 was used for a mobile phone.

(Embodiment 2) A keypad portion 6 having an average thickness of 0.5 mm and a housing having an average thickness of 1.2 mm were formed of the composite magnetic material. The keypad 6 and the housing 2 were used for a mobile phone.

(Embodiment 3) As shown in FIG. 1 (b), the composite magnetic material 9 is formed into two layers, and a nickel mesh is sandwiched as a conductor layer 10 in the middle to form a multilayer structure. 0.5mm thick keypad section 6
Was formed. The keypad unit 6 was used for a mobile phone.
Nickel mesh is 100 mesh, t = 0.1
mm.

(Embodiment 4) As shown in FIG. 1 (b), the composite magnetic material 9 is formed into two layers and a nickel mesh is sandwiched as a conductor layer 10 in the middle to form a multi-layer structure, thereby obtaining a total average thickness. 0.5mm thick keypad 6
Then, the casing 2 having a total average thickness of 1.2 mm was formed. The keypad section 6 and the housing 2 were used for a mobile phone. Nickel mesh is 100 mesh, t = 0.1
mm.

The evaluation was performed using the evaluation sample 20 having the same thickness of 0.5 mm as the average thickness of the keypad portion and the same thickness of 1.2 mm as the average thickness of the housing according to the first to fourth embodiments of the invention. The transmission attenuation level and the binding level were measured, respectively.

As shown in FIGS. 6 (a) and 6 (b), the measuring device comprises an electromagnetic wave source transmitter 21 and an electromagnetic field intensity measuring device (receiving element) 22, each having a loop diameter of 2 mm or less. An apparatus in which an electromagnetic field transmitting micro loop antenna 23 and an electromagnetic field receiving micro loop antenna 24 were connected was used.

In the measurement of the transmission attenuation level, as shown in FIG. 6 (a), the sample was positioned between the electromagnetic field transmitting micro loop antenna 23 and the electromagnetic field receiving micro loop antenna 24.

In the measurement of the coupling level, as shown in FIG. 6B, one surface of the sample and the small loop antenna 23 for electromagnetic field transmission are used.
And the minute loop antenna 24 for electromagnetic field reception.

A spectrum analyzer (not shown) is connected to the electromagnetic field intensity measuring device 22, and the measurement is performed based on the electromagnetic field intensity in a state where no sample exists.

FIG. 3A shows transmission attenuation levels of the first to fourth embodiments of the present invention and the comparative example measured by the above-described method.
FIG. 3B shows the coupling levels of the first to fourth embodiments of the present invention and the comparative example. In the first embodiment of the present invention, the second embodiment of the present invention, the third embodiment of the present invention, the fourth embodiment of the present invention, and the comparative example is a metal shield plate. The one using a stainless steel plate of t = 0.3 mm is shown in FIG.

As shown in FIG. 3, in Embodiments 1 and 2 of the present invention, the transmission attenuation level and the coupling level are both reduced.
Also, in the third and fourth embodiments of the present invention, it can be seen that the transmission attenuation level is further reduced and the shielding and absorbing effect is enhanced. It can be seen that the coupling level is not as high as in the first and second embodiments of the present invention, but is also reduced. On the other hand, in the comparative example, the transmission attenuation level is greatly reduced, but the coupling level is high. From the above results, the housing used for the mobile phone of the present invention can effectively remove radiation noise without causing secondary radiation noise due to reflection.

In the embodiment of the present invention, the conductor layer is provided by sandwiching a nickel mesh. However, a conductor film is formed by sandwiching a metal foil, electroless plating or vapor deposition, and further forming a composite magnetic material. There are various methods of multilayering with a conductor layer, such as a method of layering a body, a method of kneading a conductor powder and an organic binder to form a conductor, and achieving a multilayer structure with a composite magnetic layer, and the like. Any method may be adopted as long as a conductive layer is not provided on the substrate. Also, the number of layers is not limited to the three layers in the embodiment.

[0035]

According to the present invention, by replacing a conventional resin housing with a keypad portion made of a composite magnetic material capable of maintaining electromagnetic absorption performance even in a high frequency band, and a keypad portion and a housing, the moldability of the resin is improved. Without losing goodness,
High-frequency radiation and reflection noise can be prevented without inducing secondary radiation, and the number of parts is reduced because the shield plate is not required, so that the number of mounting steps and cost can be reduced, and the size and weight can be reduced. It is possible to provide a keypad that can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example in which a keypad of the present invention is used for a portable wireless communication terminal. FIG. 1A is a perspective view. FIG. 1B is a partially enlarged cross-sectional view of a keypad portion having a multilayer structure in which a conductor layer is sandwiched between two composite magnetic materials, or a keypad portion and a housing. FIG. 1C is a schematic exploded perspective view.

FIG. 2 is a μ-f characteristic diagram of a composite magnetic material used in an example of the present invention.

FIG. 3 is a diagram illustrating transmission attenuation levels and coupling levels according to the first, second, third, and fourth embodiments of the present invention and a comparative example. FIG. 3 (a)
FIG. 4 is a diagram showing a transmission attenuation level. FIG. 3B is a diagram showing a coupling level.

FIG. 4 is a view showing the relationship among the surface resistance, the transmission attenuation level, and the coupling level of the composite magnetic body used for the keypad, the keypad, and the housing of the present invention.

FIG. 5 is an exploded perspective view of an example in which a conventional keypad is used for a portable wireless communication terminal.

FIG. 6 is an explanatory diagram showing a measurement method for measuring a transmission attenuation level and a coupling level. FIG. 6A is an explanatory diagram showing a method of measuring a transmission attenuation level. FIG. 6B is an explanatory diagram showing a method of measuring a binding level.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cellular phone 2 Housing 3 Shield plate 4 Device 5 Substrate 6 Keypad part 7 Display 8 Battery 9 Composite magnetic layer 10 Conductive layer 20 Evaluation material 21 Transmitter for electromagnetic field wave source 22 Electromagnetic field intensity measuring device 23 Micrometer for electromagnetic field transmission Loop antenna 24 Micro loop antenna for electromagnetic field reception

Claims (6)

[Claims] 1. A keypad comprising a composite magnetic material comprising a soft magnetic material powder and an organic binder. 2. A keypad comprising a multilayer structure of the composite magnetic body and a conductor layer, and the conductor layer is not provided on an inner surface layer. 3. The keypad according to claim 1, wherein the keypad is used together with a housing made of a composite magnetic material comprising a soft magnetic material powder and an organic binder. 4. A multi-layer structure comprising said composite magnetic body and a conductor layer, and an inner surface layer is used together with a housing not provided with said conductor layer. Crab keypad. 5. The composite magnetic material according to claim 1, wherein said soft magnetic material powder is a metal magnetic material powder having an oxide film on its surface, and has a surface resistance of 10 ³ Ω or more.
6. The keypad according to any one of items 1 to 5. 6. It has at least two magnetic resonances caused by anisotropic magnetic fields of different magnitudes. The keypad according to any one of claims 1 to 5, wherein the composite magnetic body is used.