Pulse or digital communications – Pulse width modulation
Reexamination Certificate
1998-06-22
2001-01-30
Chin, Stephen (Department: 2734)
Pulse or digital communications
Pulse width modulation
C375S239000, C375S342000, C375S360000, C375S368000, C370S205000
Reexamination Certificate
active
06181741
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a remote control receiver which receives a remote control signal from a remote control which is used in a game machine, etc.
2. Description of Related Art
In a conventional game machine, a game machine body receives signals from a remote control on radio waves or infrared rays. It is convenient because a person can operate the remote control anywhere from the body of the game machine.
The above-mentioned remote control generates a remote control signal by serially arranging data in a plurality of bits, one-bit data being defined by the presence of a pulse with predetermined width. A transmitted waveform defines a pulse with use of a carrier. For instance, when the carrier is transmitted, the pulse is defined as a low level (L-level), and when the carrier is not transmitted, the pulse is defined as a high level (H-level). At the receiving side, the pulse is defined as the L-level or the H-level in the same manner.
The distance between the game machine body and the remote control varies in the transmission of the data from the remote control to the game machine body. The intensity of the signal, which the game machine body receives, varies according to the distance. For this reason, there is a disadvantage in that the data cannot be read correctly since a received waveform in the game machine body varies according to the transmission distance.
Specifically, if the remote control is close to the game machine body, or if the transmission distance is short, the pulse width of a received signal, which is reproduced by the game machine body, is larger than the pulse width of a transmitted signal, which is output from the remote control. If the remote control is far from the game machine body, or if the transmission distance is long, the pulse width of a received signal, which is reproduced by the game machine body, is smaller than the pulse width of a transmitted signal from the remote control.
The pulse width of the transmitted signal, which is output from an ordinarily remote control, is between 500 &mgr;s and 600 &mgr;s. No trouble occurs in the reception if the pulse width changes only within the range of between ±200 &mgr;s and ±250 &mgr;s. In the case of a high-speed communication which transmits the data ten times faster than a conventional communication, a change in pulse width must be within the range of ±20 &mgr;s.
Since the pulse width of the transmitted signal varies according to the transmission distance as stated above, the remote control can only be used within the transmission distance of between 1 m and 2.5 m in the high-speed communication wherein the change in pulse width is restricted within the range of ±20 &mgr;s, compared with an ordinary communication wherein the remote control which can be used within the transmission distance of between 0.2 m and 8 m. For this reason, the remote control is not practical.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of a remote control receiver which puts a remote control system, which transmits and receives a remote control signal in the high-speed communication, into practical use.
To achieve the above-mentioned object, the present invention is directed to the remote control receiver which comprises: a receiver which receives a remote control signal in which one frame is composed of a header representing a value “1”, a part with no signal representing a value “0”, and a data part with a plurality of bits representing a value “1” or “0”; a detector which detects the length of the header in each frame of the remote control signal received by the receiver; a waveform shaper for delaying a point where the remote control signal rises from “0” to “1” by a preset time, and delaying a point where the remote control signal falls from “1” to “0” to a point where the remote control signal would rise normally in accordance with the length of the header detected by the detector; and wherein the remote control signal is made a uniform length.
According to the present invention, the detection of the length of the header in the remote control signal results in the detection of a change in a point where the remote control signal falls from “1” to “0”, the point changing according to the transmission distance. The rising point of the remote control signal from “0” to “1” is delayed by a predetermined period of time, and the point where the remote control signal falls from “1” to “0” is delayed to the point where the remote control signal would fall normally in accordance with the length of the header.
This makes the remote control signals a uniform length, and corrects the data of each bit so that the data can have a proper width, regardless of the transmission distance of the remote control signal.
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patent: PCT/IB94/00329 (1994-10-01), None
Chin Stephen
Ha Dac V.
Nixon & Peabody LLP
Optec Co. Ltd.
Safran David S.
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