Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus access regulation
Reexamination Certificate
2000-03-07
2001-09-04
Nguyen, Viet Q. (Department: 2818)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus access regulation
C710S005000, C710S015000, C710S020000, C710S024000, C710S025000, C710S029000, C710S036000, C713S300000
Reexamination Certificate
active
06286071
ABSTRACT:
TECHNICAL FIELD
This invention relates to a communication control method, a communication system and an electronic device used therefor for use with electric household appliances, a personal computer (hereinafter referred to as a personal computer), peripheral equipment of such personal computer and an external memory housed within the personal computer connected to a communication control bus such as an IEEE 1394 standard serial bus.
More particularly, it may be checked whether or not a communication is effected on the specific interval of the communication control bus which was requested to be used. If the communication may not be effected on the communication control bus of such specific interval, the communication control bus of such specific interval may be opened to a set of electronic devices which had issued requests, and a connection between these electronic devices may be protected. Thus, even when signal formats of data used on that communication control bus are different from each other, the communication control bus of other specific interval in which the use requests are not overlapping can be simultaneously used by other electronic devices and such communication control bus can be utilized effectively.
BACKGROUND ART
Recently, digital video cameras having a function to transmit and receive a digital video signal and a digital audio signal by use of IEEE 1394 high-speed serial bus (hereinafter simply referred to as 1394 serial bus) have already been commercially available on the market. Also, the 1394 serial bus receives a remarkable attention as an interface for connecting peripheral equipment to a personal computer.
This 1394 serial bus may prepare an isochronous transfer mode for assuring that packets of a predetermined amount may be transmitted and received at every 125 &mgr;s and an asynchronous transfer mode suitable for transferring control commands and files although the asynchronous mode is inferior to the isochronous transfer mode in priority. For example, when digital electric household appliances such as digital video camera and a digital video deck may be connected by the 1394 serial bus, there can be transferred at a high speed real time data such as a digital video signal and a digital audio signal.
A communication system
200
connected to the electric household appliances by this kind of 1394 serial bus will be described with reference to FIG.
13
. The communication system
200
shown in
FIG. 13
may include a digital satellite receiver (Integrated Receiver Decoder: hereinafter referred to as an IRD receiver)
1
to receive digital satellite broadcasting such as a movie and a piece of music. A mini disc
2
may be connected to this IRD receiver
1
by the 1394 serial bus
6
A to record/reproduce digital data such as a piece of music received from the satellite.
Also, digital home video apparatus (hereinafter referred to as D-VHS apparatus)
3
may be connected to the IRD receiver
1
by a 1394 serial bus
6
B in a daisy-chain fashion (daisy chain fashion) to record/reproduce digital data such as a piece of music received from the satellite. A digital video deck (hereinafter referred to as a DV deck)
4
may be connected to the D-VHS apparatus
3
by a 1394 serial bus
6
C in a daisy-chain fashion to record/reproduce digital data such as recording video data. A video recorder having a built-in type camera (hereinafter referred to as a DV camera/recorder)
5
may be connected to the DV deck
4
by a 1394 serial bus
6
D in a daisy-chain fashion to record/reproduce digital data such as recording video data.
MPEG transport stream data (hereinafter referred to as MPEG data) based on the moving picture compression system may be transferred among the IRD apparatus
1
, the mini disc
2
and the D-VHS apparatus
3
, and digital video data (hereinafter referred to as DV data) may be transferred between the DV deck
4
and the DV camera/recorder
5
. For example, in the communication system
200
shown in
FIG. 13
, the digital video signal and the digital audio signal recorded by the DV camera/recorder
5
may be played back and these DV data may be recorded by the DV deck
4
.
According to the conventional communication system
200
, when digital household equipment for handling MPEG data and DV data having different signal formats may be connected to the 1394 serial buses
6
A to
6
D, the DV camera/recorder
5
which had been served as a digital video signal output machine, for example, to issue a bus use request and which had acquired the bus use right may output a digital video signal to a default channel No. (e.g. channel
63
) on a previously-prescribed bus management.
Then, the DV deck
4
which, may be used as the digital video signal input machine may input a digital video signal from the same default channel No. Thus, the digital video signal can be easily transmitted and received between the DV camera/recorder
5
and the DV deck
4
which had acquired the bus use right with the priority to the IRD receiver
1
used as the output machine.
However, according to the conventional communication system
200
, if the DV camera/recorder
5
and the DV deck
4
shown in
FIG. 13
may use the 1394 serial bus
6
D which is the specific interval in which they had previously acquired the bus use right with the priority to digital household equipment which can become other output machines, the IRD receiver
1
and the mini disc
2
cannot use the 1394 serial bus
6
A and the IRD receiver
1
and the D-VHS apparatus
3
cannot use the 1394 serial bus
6
B.
The reason for this may be considered such that DV data may enter the 1394 serial buses
6
A to
6
C for which the DV camera/recorder
5
and the DV deck
4
have not issued the bus use requests so that the IRD apparatus
1
, the mini disc
2
and the D-VHS apparatus
3
which may handle MPEG data cannot receive the DV data.
Therefore, although the 1394 serial buses (hereinafter referred to as communication control buses)
6
A and
6
B have sufficient available channels and bandwidths (bus resources) to handle MPEG data, such available channels and bandwidths cannot be used between the IRD receiver
1
and the mini disc
2
and the IRD receiver
1
and the D-VHS apparatus (hereinafter referred to as electronic device)
3
. In this connection, it may become difficult to record a piece of music or the like digitally received at the IRD receiver
1
from the satellite on the mini disc
2
or to record a movie received at the IRD receiver
1
on the D-VHS apparatus
3
at the same time DV data may be recorded on the DV deck
4
from the DV camera/recorder
5
.
As a result, there arises a problem that applications that can input and output signals on the communication system
200
may be limited, thereby making it impossible to utilize the bus resource effectively.
Therefore, in view of the above-described aspect, the present invention is created and, an object of the present invention is to provide a communication control method, a communication system and electronic devices used therefor in which even when signal formats of data used on the communication control bus are different from each other, communication control buses of other specific intervals in which use requests are not overlapped can be simultaneously used by other electronic devices and the communication control bus can be utilized effectively.
DISCLOSURE OF THE INVENTION
In a communication control method according to this invention, a method of controlling a communication between a plurality of electronic devices connected by a communication control bus in a daisy-chain fashion comprises the steps of receiving bus use requests from both of an electronic device serving as an output machine on the communication control bus and an input machine serving as an input machine on the communication control bus, checking whether or not a specific interval of the communication control bus which was requested to be used is used and opening the communication control bus of the specific interval to an electronic device of signal input/output pair which we
Frommer William S.
Frommer & Lawrence & Haug LLP
Nguyen Viet Q.
Sony Corporation
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