Telecommunications – Transmitter and receiver at separate stations
Reexamination Certificate
1995-07-18
2001-04-17
Eisenzopf, Reinhard J. (Department: 2745)
Telecommunications
Transmitter and receiver at separate stations
C455S107000, C455S292000
Reexamination Certificate
active
06219529
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique for short-range data transfer between terminal devices used for compact and portable information terminal devices such as wireless handy terminals.
2. Description of the prior Art
Conventional short-range data transfer techniques for compact and portable information terminal devices utilize electromagnetic induction which occurs between electromagnetic coils in data transmission and reception portions. Such electromagnetic induction can be described as the relationship between an electrical field E and a magnetic field H given by the following equations (i.e. Maxwell's electromagnetic field equations).
rotE=−&mgr;dH/dt (1)
rotH=−&egr;dB/dt (2)
In the above equations (1) and (2), A represents as a permeability; &egr; represents a dielectric constant; and t represents time.
FIG. 6
shows the scheme of the conventional short-range data transfer wherein electromagnetic coils are used in data transmission and reception portions. When an alternating current
26
including signal is applied to an electromagnetic coil
25
of a transmission portion
24
, an a.c. magnetic field H is produced and an electrical field E is also induced according to Equation (1). In other words, when the alternating current
26
is applied to the electromagnetic coil
25
of the transmission portion
24
, an electromagnetic wave
27
caused by interaction between the magnetic field H and induced electrical field E produced at the electromagnetic coil
25
of the transmission portion is radiated in a space. When the electromagnetic wave
27
radiated in the space is detected by an electromagnetic coil
29
of a reception portion
28
, a current I
30
and a magnetic field are induced at the electromagnetic coil
29
of the reception portion
28
in accordance with Equations (1) and (2). The data at the transmitting end can be transferred to the receiving end by analyzing the induced current I
30
. The conventional method of short-range data transfer techniques utilizing electromagnetic induction is summarized above. Such short-range data transfer techniques are widely used due to the simple circuitry employed, although the technique is less desirable in terms of transfer speed, transfer distance and the like than wireless communication techniques such as those used in portable telephones (mobile telephone systems) and radios.
Usually, it is required for a compact and portable wireless terminal to have the function of communication with the parent terminal and the function of communication with other offsprings. Such data transfer is carried out in a short-range such as several centimeters or in a state wherein the terminals are in contact with each other. In such situations, the electromagnetic induction system using electromagnetic coils as described above is required. Therefore, a compact and portable wireless terminal incorporates an analog circuit portion for transmission and reception of electrical waves in the range from several tens of MHz to several tens of GHz to be used for wireless communication (hereinafter referred to as RF circuit) and a relatively simple data transmission/reception circuit portion for performing short-range data transfer utilizing electromagnetic induction (hereinafter referred to as an electromagnetic induction circuit). As is apparent from Equations (1) and (2), a current I induced at the electromagnetic coil of the receiving end of the electromagnetic induction circuit is increased in proportion with the frequency of the signal to be transferred. Therefore, although the reception sensitivity is sufficient for transferred signals of high frequencies, the sensitivity is insufficient for low frequencies. This has resulted in a serious problem with data transfer systems using normal electromagnetic induction coils in that they can transfer only signals of high frequencies. Especially, transfer has been almost impossible for signals having frequencies of several tens of Hz or lower. This problem has necessitated designers to indiscriminately increase the frequency of signals to be transferred by short-range data transfer systems such as compact and portable wireless terminals in order to improve reception sensitivity. This has inevitably resulted in an increase in the power consumption of such an electromagnetic induction circuit which has created a serious problem in product design.
SUMMARY OF THE INVENTION
Essentially, the above-described problem is inevitable in systems utilizing electromagnetic induction. In order to solve this problem, according to the present invention, an amorphous magnetic impedance element is included in a data reception circuit. The amorphous magnetic impedance element (hereinafter referred to as and MI element) is an element in the form of a bulk or film of the type which has recently been attracting attentions as a high sensitivity magnetic sensor and whose impedance component changes greatly in response to application of a magnetic field thereto with an alternating current supplied. For example, see “FET Utilizing Amorphous MI Elements for 200 MHz Sensor Oscillator”, Magnetics Research Institute Ref. No. MAG-93-99, published by DENKI GAKKAI (Institute of Electrical Engineers). As shown in
FIG. 7
, an electrical equivalent circuit for this MI element is constituted by an actual resistance component Rs and an inductance component Ls. When a magnetic field is applied, both or one of the Rs and Ls components of this element undergoes a significant change. Further, the MI element has the following major characteristics.
First, the impedance changes in response to the application of a magnetic field with high sensitivity which is exhibited for magnetism as low as 0.1 gauss or less.
Secondly, the magnetic fields which can be detected by this element include static magnetic fields and magnetic fields of high frequencies on the order of 10 MHz.
Thirdly, this element can be processed in extremely small dimensions such as a length of 1 mm or less and a diameter or thickness of 100&mgr; or less.
Fourthly, the electrical parameters to be changed (Rs and Ls) and the sensitivity can be freely selected depending on the conditions for the formation and packaging of the element.
In summary, the present invention is characterized in that a data reception circuit is configured using such an MI element instead of an electromagnetic coil.
The use of an MI element having the characteristics described above as an electromagnetic wave receiving element of a data reception circuit allows reception over a wide frequency band that covers static magnetic fields which do not oscillate over time and alternating current magnetic fields on the order of 10 MHz. As a result, the frequency for data transfer may be arbitrarily selected unlike reception circuits utilizing electromagnetic coils for which the frequency is limited to a high frequency band. This makes it possible to reduce the power consumption of a product to a value which is appropriate for the product.
Further, since the element itself is compact as described above, it is possible to make a product using the element compact. Another significant feature provided by the use of this MI element is that the configuration of the data transmitting end is not limited to an electromagnetic coil because the element directly detects changes in the magnitude and strength of a magnetic field. For example, it is possible to provide a purely mechanical transmission mechanism constituted by a simple magnet and a mechanical magnetic shielding mechanism which operates in conjunction with transmission data. The use of this MI element allows wireless data transfer (the so-called magnetic field communication) utilizing only changes in the magnitude and strength of a magnetic field.
REFERENCES:
patent: 3660760 (1972-05-01), Schaad et al.
patent: 3787772 (1974-01-01), Sedin
patent: 3898565 (1975-08-01), Takeuchi et al.
patent: 3953799 (1976-04-01), Albee
patent: 4071714 (1978-01-01), Sa
Inokoshi Yoshio
Kamimoto Takashi
Kimura Fumio
Kuwahara Seiji
Miyoshi Tatsuo
Adams & Wilks
Eisenzopf Reinhard J.
Kincaid Lester G.
Seiko Instruments Inc.
LandOfFree
Wireless communication system using only the magnetic field... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Wireless communication system using only the magnetic field..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wireless communication system using only the magnetic field... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2457503