Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1999-02-04
2001-09-04
Hunter, Daniel (Department: 2684)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S575100, C455S129000, C455S269000, C455S090300
Reexamination Certificate
active
06285893
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a portable radio device removably fitted to a mobile body, more particularly, to a portable radio device fitted to a mobile body which is a human body.
2. Description of the Related Art
In a mobile radio communication system, a radio device, such as a radio-paging device (pager) or a portable telephone, which is of a portable type and is not fixed to a mobile body, has been popularized in recent years, besides a communication device fixedly provided in a mobile body such as a vehicle. Furthermore, a portable radio device is used not only for ringing or voice communication but also for various data transmission.
Generally, in a mobile radio communication system, the communication quality is largely affected by interference due to the multiple radio wave paths or fading associated with the movement of a mobile body and so on, and then various countermeasures have been disclosed for suppressing such interference.
For example, in “Mobile Radio Reception System” disclosed in Japanese Patent Application Laid-Open No. 58-46892 (JP 58-46892/1983), three or more directional antennas, each having directivity within a limited angular range in a horizontal plane, are disposed such that each antenna forms an antenna directivity pattern in a respectively different directions and as a whole to be nondirectional. The signal strength received from each of these antennas is compared with a predetermined threshold to switch the output from each antenna, thereby performing diversity reception. In the application of this system, the antenna are necessarily integrated with a receiver. A radio device having antennas fixedly mounted to a mobile body such as a vehicle is the most appropriate.
Additionally, “Portable Radio Device” disclosed in Japanese Patent Application Laid-Open No. 3-6927 (JP36927/1991) comprises an antenna and components having a removable metal portion, such as a battery, and a single housing. For the purpose of suppressing the affect of the mounting state of those components on the antenna characteristics, the portable radio device is provided with determining means for determining the mounting state of the components and control means for controlling various constants which define the characteristics of the antenna in accordance with the determined mounting state of the components.
On the other hand, a small device among the above-mentioned portable radio devices, for example a portable radio receiver for broadcasting or a portable telephone, typically has a single antenna provided inside or attached outside a housing of the communication device. While moving time along, the entire communication device is used while being fitted to a human body by putting the entire communication device including the antenna in a bag or a pocket of clothing, or by holding the device in a holding case attached to a belt.
When the portable radio device is fitted to the human body as described above, typically it is not specified which surface of the housing of the portable radio device is disposed closely to the human body. If the surface of the housing on which the antenna is disposed is close to the human body, the directivity of the antenna may be disturbed by the human body to deteriorate the reception sensitivity and the transmission incident power.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a portable radio device which can obtain a favorable state of radio wave transmission and reception when the portable radio device is fitted for use to a mobile body which affects the propagation of the radio wave, especially to a human body, with a surface of the device being fitted to the mobile body.
To achieve the above object, a portable radio device according to the present invention has a radio communication unit including at least one of either a transmitter or a receiver for radio waves; a device housing for holding the radio device and removably fitted to a mobile body; a plurality of antennas dispersedly disposed at positions away from one another in the device housing; a plurality of sensors provided corresponding to each of the plurality of antennas and for detecting an object close to the device housing; and a switching circuit for comparing detection results of the respective sensors and selectively switching one of the antennas to be connected to the radio communication unit.
The sensor may include one of an optical sensor, a strain sensor, and a temperature sensor or a combination of two or more of the above sensors.
The optical sensor is a reflection type optical sensor having a light emitting device and a light detection device, in which light is emitted from the light emitting device in a specific direction to detect the reflected light from a interception object at with light detection device. The strain sensor is a pressure sensor for sensing, when the device is contacted with another object, the contact pressure with the strain of the contact surface. The temperature sensor detects the temperature such as the temperature radiated from a human body to sense the approaching of a heat source.
The switching circuit receives detection outputs from the plurality of sensors, determines the fitting surface of the device housing contact with the mobile body, and selects one of the antennas corresponding to the fitting surface when the power of the radio communication unit is put on.
The switching circuit may periodically receive the detection outputs from the plurality of sensors at certain time intervals or occasionally when indication input is received.
As described above, the present invention has effects that the directivity of the antennas properly functions, a favorable transmission state of radio waves can be obtained, and an improvement in the reception sensitivity and the transmission characteristics can be achieved by detecting the fitting direction of the device housing with respect to the mobile body using a plurality of sensors, selecting the optimal antenna corresponding to the detection result, and connecting the selected antenna to the communication circuit.
The above and other objects, features, and advantages of the present invention will become apparent from the following description referring to the accompanying drawings which illustrate an example of a preferred embodiment of the present invention.
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Japanese Patent Laid-OpenGgazette No. 60123/81 (JP,A,56-60123) as for English abstract of Japanese Patent Laid-open Gazette 46892/83 (JP,A,58-46892), dated May 23, 1981.
Japanese Patent Laid-Open Gazette No. 6927/91 (JP,A,3-6927), dated Jan. 14, 1991.
Japanese Patent Laid-Open Gazette No. 200889/95 (JP,A,7-200889), dated Aug. 4, 1995.
Japanese Patent Laid-Open Gazette No. 200897/95 (JP,A,7-200897), dated Aug. 4, 1995.
Hunter Daniel
NEC Corporation
Scully Scott Murphy & Presser
Zewdu Meless
LandOfFree
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