Television – Basic receiver with additional function – Multimode
Reexamination Certificate
2000-05-19
2004-05-25
Kostak, Victor R. (Department: 2714)
Television
Basic receiver with additional function
Multimode
C348S555000, C348S731000, C455S161300
Reexamination Certificate
active
06741293
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a broadcast receiving device and a broadcast reception and output method, particularly to those that are made adaptable to the conditions of received broadcast waves that change with the move of a mobile body furnished with such equipment by taking advantage of both digital and analog broadcast merits.
2. Description of the Related Art
With digital television broadcasting about to begin in Japan, the development of digital TV receiving equipment for mobile applications is in progress. Japanese Patent Laid-Open Publication No. Hei 9-307517, for example, proposes equipment related to digital television broadcasting. Digital broadcasting has advantages in that digital broadcasting can provide higher quality images and sound over analog broadcasting.
As is well-known, digital TV broadcast receivers assure a higher quality of reception by carrying out error correction. If, however, the electric field of received broadcast waves is below a certain level, error correction cannot be performed and no images can be reproduced. This phenomenon is referred to as a cliff effect. When providing a digital broadcast receiver installed on a mobile body, the field intensity of received broadcast signals change as the body moves. Thus, there is a possibility that the field intensity of a received signal will become so low that no images can be obtained due to the cliff effect.
Analog signals have a demerit that ghosts or blurred colors may occur, due to the affect of multiple paths, even when the power of received broadcast waves is sufficiently large. However, unlike digital broadcasts, analog broadcasts are free from the cliff effect. Even when the field intensity of received broadcast waves becomes low during the move of a mobile body equipped with an analog broadcast receiver, the receiver can continue to generate video and audio outputs, though image and sound quality decrease.
As described above, digital broadcasts have higher quality, but no images can be obtained from them when the field intensity of received broadcast waves is below a certain level. In contrast, analog broadcasts can continue to produce images, no matter how low the field intensity of received broadcast waves becomes low.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a broadcast receiver and a broadcast reception and output method that are adaptable to the conditions of received broadcast waves that change with the move of a mobile body furnished with such equipment through the selective use of digital and analog broadcast characteristics.
The broadcast receiver equipment according to the present invention comprises a digital broadcast receiver portion for receiving at least one digital broadcast channel; an analog broadcast receiver portion for receiving analog broadcasts including a channel for transmitting the same content broadcast as on at least one of the digital broadcast channels that can be received by the digital broadcast receiver portion; a receive condition sensing means for sensing the condition of either or both of the digital and analog broadcast waves received by the digital and analog broadcast receiver potions; a channel selection switch for carrying out channel selection, based on predetermined processing; selection means for selecting either the digital or analog broadcast when the channel selection switch has selected a pair of digital and analog channels from which same content broadcasts are received, according to the conditions of received broadcast waves, as sensed by the receive condition sensing means; and a broadcast output means for outputting the selected broadcast.
In the broadcast receiver of the present invention, when broadcasts of the same content are received from a pair of digital and analog channels which have been selected by the channel selection switch, based on predetermined processing, the selection means selects either the digital or analog broadcast, according to the conditions of either or both of the digital and analog broadcast waves received by the digital and analog broadcast receiver portions, as sensed by the receive condition sensing means, and the broadcast output means outputs the selected broadcast. Thus, the present invention enables selective output of digital or analog signals of better quality, because the broadcast output is switched between the received digital and analog broadcasts, according to the conditions of either or both of the digital and analog broadcast waves received by its digital and analog broadcast receiver portions. The broadcast in the above description can be exemplified by TV broadcasting, but are not limited to this, and any kind of broadcasting, such as radio broadcasting, may be applicable to the present invention. The “predetermined processing” of the channel selection switch includes operation by the user and an automatic search executed when the receiver is powered up.
This broadcast receiver of the present invention may operate so that the receive condition sensing means senses the conditions of the digital broadcast waves received by the digital broadcast receiver portion. If this is implemented, the device can switch over between digital and analog broadcasts to be output, according to the conditions of received digital broadcast waves that produce clearer sound and images.
When the broadcast receiving equipment according to the present invention is intended to perform digital/analog broadcast switching according to the conditions of received digital broadcast waves, its receive condition sensing means may detect the error rate of packets during the demodulation of the received digital broadcast signals as an index of the conditions of the received waves. If this is implemented, the device can easily determine whether the strength of the received digital broadcast is sufficient to obtain output such as images. When operating in this manner, the broadcast receiving equipment of the present invention can be preset so that its selection means selects the digital broadcast if the error rate of packets detected as the index of the conditions of the received digital broadcast waves is less than a predetermined rate or select the corresponding analog broadcast if this error rate is equal to or greater than the predetermined rate.
Alternatively, when the broadcast receiving equipment according to the present invention is intended to perform digital/analog broadcast switching according to the conditions of received digital broadcast waves, its receive condition sensing means may detect the received power level of the received digital broadcast signals as the index of the conditions of the received digital broadcast waves. Because the received power level is closely related to the received wave conditions, more adequate digital/analog broadcast switching can be performed according to the received power level. When operating in this manner, the broadcast receiving equipment of the present invention can be preset so that its digital/analog selection means selects the digital broadcast if the received power level is equal to or higher than a predetermined level or select the corresponding analog broadcast if this level is lower than the predetermined level.
The broadcast receiver of the present invention also may operate so that its receive condition sensing means senses the conditions of the analog broadcast waves received by the analog broadcast receiver portion. If this is implemented, the equipment can switch over between digital and analog broadcasts to be output, according to the conditions of received analog broadcast waves.
In the broadcast receiver according to the present invention, furthermore, the receive condition sensing means may comprise a received video conditions sensing means for sensing the conditions of the video of the received broadcast waves and a received audio conditions sensing means for sensing the conditions of the audio of the received broadcast waves. Moreover, the selection means may comprise a vi
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kostak Victor R.
Toyota Jidosha & Kabushiki Kaisha
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