(19) 0
`
`)
`
`E"*°"““s°“°s"a‘°"‘am‘
`
`European Patent Office
`Office européen des brevets
`
`llllllllllllllllllllllllllllllllllllllllllIllllllllllllllllllllllllllllllll
`
`(11)
`
`EP 0 950 570 A2
`
`(12)
`
`EUROPEAN PATENT APPLICATION
`
`(43) Date of publication:
`20.10.1999 Bulletin 1999/42
`
`(51) Int. CLG: 360R 11/02
`
`(21) Application number: 99105608.6
`
`(22) Date of filing: 19.03.1999
`
`(84) Designated Contracting States:
`AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU
`
`MC NL PT SE
`Designated Extension States:
`AL LT LV MK RO SI
`
`(30) Priority: 24.03.1998 JP 7611598
`14.04.1998 JP 10229198
`
`(71) Applicant: CLARION Co., Ltd.
`Tokyo (JP)
`
`(72) Inventors:
`- Ido, Kazuhiro
`c/o Clarion Co., Ltd.
`TOKYO (JP)
`
`- Chubachi, Yoshiki
`c/o Clarion Co., Ltd.
`Tokyo (JP)
`- Uehara, Nagatoshi
`c/o Clarion Co., Ltd.
`Tokyo (JP)
`- Hamashima, Sadafumi
`c/o Clarion Co., Ltd.
`Tokyo (JP)
`
`(74) Representative:
`Fritsche, Rainer, Dipl.-Wirtsch.-lng.
`Eisenfiihr, Speiser & Partner
`Patentanwalte
`Arnulfstrasse 25
`80335 Miinchen (DE)
`
`
`
`(54)
`
`Automotive information system, automotive computer system, and method of controlling
`the automotive information system
`
`FIG.
`
`1
`
`
`
`An automotive information system including a
`(57)
`car audio system and other information units or devices
`is controlled by a small-sized computer that is also part
`of the automotive information system and that is loaded
`with a general-purpose OS. The automotive information
`system has a local BUS of a form conforming with the
`data form of the CPU, a PCI BUS that interconnects the
`units or devices of the system, and a PCI BUS boot con-
`troller that performs form conversion of data exchanged
`between these two types of BUSes. Audio data which
`may be analog or digital and other data which are inher-
`ently digital are transmitted in the form of digital signals
`through the PCI BUS, and these data are processed
`digitally by the CPU. With this arrangement, the small-
`sized computer and information devices such as a car
`audio system are combined in such a manner as not to
`impair the advantages of the computer and the informa-
`tion devices. Audio data when it is formed of analog sig-
`nals is audio-to-digital-converted into audio signals in
`the form of digital signals. Thus, audio data and other
`digital data are transmitted through a common digital
`circuit, so that the wiring layout is simplified and audio
`characteristic is stabilized against noise and change in
`the environmental conditions.
`
`EP0950570A2
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`EP 0 950 570 A2
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`2
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`Description
`
`Background of the Invention
`
`1. Field of the Invention
`
`[0001] The present invention relates to an automotive
`Information system which operates under the control of
`a small-sized computer.
`In this specification, the term
`"automotive information system" is used to mean a sys-
`tem that is used on a vehicle such as an automobile and
`
`that consolidates one or more of a plurality of informa-
`tion apparatuses such as a car audio system, a car nav-
`igation
`system,
`a voice
`recognition
`system for
`recognizing driver's order, a hand-free mobile tele-
`phone, a security system, and so forth. The present
`invention also is concerned with an automotive compu-
`ter system. The invention further pertains to a method
`Of controlling an automotive information system.
`
`2. Description of the Related Art
`
`In recent years, remarkable progress has been
`[0002]
`achieved in the field of semiconductors, enabling minia-
`turization and sophistication of various electronic
`devices incorporating semiconductors. Personal com-
`puters (referred to also as "PCs", hereinafter) are typical
`examples of electronic devices that are experiencing
`reduction in sizes and improvement in performance by
`virtue of the progress in the field of semiconductor.
`[0003]
`In particular, small-sized computers such as
`handheld-type computers and so-called palm-top com-
`puters are finding spreading use. Such small-sized
`computers will be inclusively referred to as a "handheld
`computer", hereinafter. Such handheld computers
`employs a basic software,
`i.e., an operating system
`(referred to also as "OS", hereinafter), typically a gen-
`eral-purpose OS known as Windows CE (registered
`trademark of Microsoft Corporation).
`[0004]
`Such a general-purpose OS exquisitely man-
`ages CPU and memories in the computer,
`thereby
`implementing high-degree of processing ability, while
`providing standard user-interfaces that are easy to use
`and that have no dependency on the programs. The OS
`also permits free modification or addition of program,
`provided that such programs comply with predeter-
`mined forms supported by the OS, thus enabling addi-
`tion or modification of functions to be performed by the
`computer.
`[0005] Another example of electronic devices that are
`on their way towards reduction in size and improvement
`in the performance arc automotive information appara-
`tuses such as car audio systems, car navigation sys-
`tems, and so forth. The car audio system is a system
`which is referred to also as a "car stereo" and which
`
`consolidates various components such as a CD player,
`AM/FM tuners, amplifiers and speakers, The car navi-
`gation system is a system which locates the instant
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`position of an automobile based on the outputs of
`devices such as an azimuth magnet, a trip meter and a
`GPS, and guides the driver to a designated destination
`by showing the momentary positions on a map dis-
`played on a screen.
`
`[0006] There is a current trend that a car audio system
`is combined with other automotive devices or systems
`such as a car navigation system, hand-free mobile
`phones and security system. A system that consoli-
`dates these automotive devices and systems will there-
`fore be referred to as an automotive information system,
`as stated before.
`
`Conventionally, handheld personal computers
`[0007]
`having an OS of the type mentioned before and automo-
`tive information systems or the kind stated above have
`been designed and manufactured separately from and
`independently of each other. Although there have been
`car audio systems that incorporate a computer in gen-
`eral sense, such a computer is a kind of processor or a
`built-in system designed only for specific purposes and
`is fundamentally different from a handheld computer
`loaded with a general-purpose OS.
`[0008]
`More specifically, such a built-in system
`employs a CPU having minimum required functions.
`Namely, the built-in system implements, by means of
`simple programs relying on an assembler, minimum
`required tasks to be performed on hardware, e.g., rec-
`ognition of a switch operation, activation and deactiva-
`tion off a disk playback mechanism, and so forth. Such
`a built-in system, unlike a handheld personal comput-
`ers, cannot cope with demands for versatility or func-
`tions
`such as processing and storage of data,
`modification or addition of a program, and so on.
`[0009] Meanwhile, a handheld personal computer by
`itself cannot perform functions such as playing a music
`or controlling a car audio system. Therefore, a user of a
`handheld computer, even when be happened to bring
`his computer into an automobile, cannot use the com-
`puter in relation to the car audio system that is installed
`on the automobile.
`
`It is a current trend that a car audio system,
`[0010]
`having conventional components such as radio tuners,
`cassette tape deck, CD player and so on, are combined
`with other devices such as an MD player, a CD/MD
`auto-changer, a car navigation system, a voice recogni-
`tion system for recognizing driver's order, hand-free
`mobile phones, a security system, and so forth, thus
`providing a complicated automotive information system.
`It is not easy for the driver to manage such a compli-
`cated automotive information system by manipulating
`various switches provided on individual component
`devices or systems of the automotive information sys-
`tem.
`
`[0011] Namely, such a complicated automotive infor-
`mation system composed of many component devices
`or systems inevitably has many keys, buttons, dials and
`switches which are located at various positions on the
`dashboard or console. This heavily burdens the driver
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`EP 0 950 570 A2
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`4
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`because the driver has to understand and remember
`
`the locations of various keys, dials and switches.
`
`In order that the car driver can easily and effi-
`[0012]
`ciently use a complicated automotive information sys-
`tem which becomes complicated more and more,
`it is
`desirable that the system is controlled by a compact
`computer that has a high grade of processing perform-
`ance suitable for controlling the complicated system and
`that provides user-friendly user interface while affording
`addition or modification of controlling function, specifi-
`cally an information processing apparatus equivalent to
`a handheld personal computer loaded with a general-
`purpose OS.
`[0013]
`In view of the current automotive society and
`heavy traffic congestion,
`it is desirable also from the
`view point of computer-related industries that handheld
`computers find spreading use by being combined with
`automotive information equipment.
`In particular, a
`handheld computer when combined with an automotive
`information system enhances utilities of both the hand-
`held computer and the automotive information system.
`For instance, operation keys and memories can be used
`commonly both for the handheld computer and the
`automotive information system. When the driver needs
`a certain type of information, the handheld computer
`provides the information by way of synthesized voice
`message which is output from a speaker of the car
`audio system, so that the driver can obtain the informa-
`tion by listening to the voice message. When the auto-
`motive information system includes a mobile phone, the
`handheld computer on the automobile can make access
`to an external computer network via the telephone com-
`munication line. Thus, the utility of the automotive infor-
`mation system, as well as that of
`the handheld
`computer, can be enhanced advantageously.
`[0014]
`In general, a CPU adapted to use a general-
`purpose OS operates at a high speed. Therefore, when
`such a CPU is used in combination with devices or sys-
`tems included in the automotive information system
`which may fail to operate at high speed, it is desirable
`that different BUSes are used for the CPU and the auto-
`
`in order to accommodate
`motive information system,
`the difference in the operation speed. It is also desirable
`that component devices and systems constituting the
`automotive information system are connected by a sim-
`ple and neat wiring layout.
`[0015] A car audio system included in the automotive
`information system which is controlled by a computer or
`which incorporates a computer-controlled electronic
`device essentially handles information in the form of
`digital data in addition to audio information such as a
`music. For instance, when the car audio system is oper-
`ating in a paying mode or a rewinding mode, a message
`reading PLAY or REW is displayed on a display section
`such as a liquid crystal display unit. To this end, charac-
`ters to be displayed are formed by digital data such as
`character codes or dot patterns.
`[0016]
`In an automotive information system incorpo-
`
`rating a car navigation system, data such as programs
`and maps are read from a CD-ROM and are developed
`into a bit map corresponding to maps and characters so
`that the maps and characters are displayed on the liquid
`crystal display screen.
`
`In this specification, data which is inherently
`[0017]
`digital will be referred to as "digital data", while sound
`data such as of music will be referred to as "audio" data,
`regardless of whether it is in the form of analog or digital
`form.
`
`In the known automotive information system
`[0018]
`having a car audio system, constructions of various
`parts are rendered complicated, due to the fact that
`audio data is handled by a circuit which is different from
`that used for handling digital data such as character and
`image data.
`[0019]
`For instance, in an automotive information sys-
`tem having a CD-ROM auto changer which is capable of
`reading data both from a music CD and a CD-ROM and
`which is connected to a car audio system, the audio
`data road from the music CD is lent to an amplifier via
`an analog signal line, while digital data read from the
`CD-ROM is sent to the car navigation system via a dig-
`ital communication line such as a BUS.
`It is therefore
`
`necessary that connectors are used for respective
`Component devices or systems of the automotive infor-
`mation system, with the result that the construction of
`the whole system is complicated
`[0020]
`In addition, intricate connecting wiring systems
`having many connection cords have to be used for
`achieving mutual connections between the component
`devices or systems of the automotive information sys-
`tem. Consequently,
`laborious work is necessary for
`accomplishing the connection, as well at for protective
`maintenance and repair. This problem is becoming seri-
`ous because the number of components consolidated in
`automotive information systems is increasing. There is
`a trend that the users separately purchase desired com-
`ponent devices or systems that are sold as option parts
`and requests the car dealer to assemble them together
`to form a consolidated system or to add a new compo-
`nent device or system to an listing system which has
`already been set up on the automobile.
`[0021]
`It
`is quite difficult to determine the wiring
`scheme, i.e., the components to be mutually connected,
`connectors of each component to be used for achieving
`the connection, type of the cable to be used, and so
`forth. The number and the types of the connectors vary
`according to the component devices.
`It is also neces-
`sary to suitably select the type of the connectors and
`cables, e.g., conventional audio cables for analog sig-
`nals, digital communication cables for digital data, opti-
`cal fibers, and so forth.
`[0022]
`After the automotive information system has
`safely been set up, if the user wishes to add a new com-
`ponent device or system, it is necessary to modify the
`wiring layout in which various kinds of cables are laid in
`an intricate manner, in order to connect the additional
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`EP 0 950 570 A2
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`component device or system.
`
`For the purpose of modifying the wiring layout,
`[0023]
`it say become necessary to disconnect the existing
`cables. The connections have to be restored after con-
`
`it is
`necting the new component device. To this end,
`necessary to make a memo or record concerning the
`positions and types of the cables before they are dis-
`connected. Making such a memo or record alone is
`quite a troublesome work. This problems is encoun-
`tered also when the cables are disconnected forthe pur-
`pose of protective maintenance or repair.
`[0024]
`Further, different types of cables have different
`natures and require different kinds of attention in han-
`dling. Thin also is a factor that makes it difficult to deter-
`mine and execute the wiring layout. For instance, a
`cable designed to electrically transmit digital signals can
`sustain bending to some extent but
`is liable to be
`affected by electrical noises.
`In contrast, optical fibers
`are not resistant to bonding, although they are less
`likely to be influenced by electrical noises. Cables for
`analog signals undesirably pick up strong electrical
`noises. Thus, different types of cables have to be han-
`dled and treated differently The routing of the cables,
`i.e., the paths along which the cables are to be laid must
`be determined with deliberative consideration.
`
`[0025] Known car audio systems have a drawback in
`that, when audio signals are transmitted through an
`analog circuit, the audio characteristic is undesirably
`deteriorated due to a change in environmental condition
`such as temperature and humidity or due to influence of
`noises. For instance, the signal frequency which can be
`best transmitted through an analog signal cable varies
`depending on the temperature.
`[0026] The user of a car audio system can set up the
`best condition, e.g., tone, balance and so forth, of play-
`back of music, by using, for example, a graphic equal-
`izer. However, the actual playback condition tends to
`deviate from the set best condition due to a change in
`the audio characteristic caused by a variation of the
`environmental condition or by noise. The user therefore
`has to set up again the payback condition so as to can-
`cel
`the deviation. Frequent change of
`setting is
`extremely troublesome. The change in the audio char-
`acteristic is serious particularly in audio systems used
`on automobiles, considering that automobiles are sub-
`jected to a variety of conditions of use, depending on
`the district, season, habits of the drivers, and so on.
`[0027]
`Conventional automotive information system
`employs a wiring system in which cables or lines led
`from various component units are concentrated to a
`central unit which is also referred to as a "hub". This
`
`style of wiring is quite inconvenient
`conventional
`because all the wires and lines from various component
`units located at various positions on the automobile are
`concentrated to the hub.
`
`[0028] This conventional wiring system retires cables
`and lines of greater lengths. This not only renders the
`wiring work troublesome but enhances the risk of
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`change in the audio characteristic due to noise and
`change in the environmental condition. In addition, con-
`centration of many cables and lines to the central hub
`further impedes addition of a component unit, protective
`maintenance and repair, because of difficulty encoun-
`tered in disconnecting and connecting the cables and
`lines.
`
`SUMMARY OF THE INVENTION
`
`it is a first object of the present
`Accordingly,
`[0029]
`invention to provide an automotive information system,
`as well as an automotive computer system and a
`method of controlling an automotive information sys-
`tem, in which a small-sized computer such as a hand-
`held computer using a general purpose OS is combined
`with information devices or systems that are used on
`automobiles. More specifically,
`the combination is
`achieved in such a manner as to enable maximum use
`
`of the merits and functions of both the computer and the
`information devices and systems, thus offering advan-
`tages that could never be achieved by the known arts.
`[0030]
`It is a second object of the present invention to
`provide an automotive information system, as well as an
`automotive computer system and a method of control-
`ling an automotive information system, which employs a
`plurality of types of BUSes so us to permit both a high-
`speed computer and automotive information devices or
`systems to operate at their optimum operation speeds,
`thus eliminating idle time.
`[0031]
`It is a third object of the present invention to
`provide an automotive information system, as well as an
`automotive computer system and a method of control-
`ling an automotive information system, in which various
`automotive information devices and systems are con-
`nected in a manner like a sweet-potato-vine,
`thus
`achieving a rational wiring layout.
`[0032]
`It is a fourth object of the present invention to
`provide an automotive information system which is
`arranged to permit both audio data and other inherently-
`digital data can be transmitted through a common digital
`circuit.
`
`To this end, according to one aspect of the
`[0033]
`present invention, there is provided an automotive infor-
`mation system comprising a controlling computer; the
`computer having a CPU ad an operating system; the
`operating system including: means for administrating
`resources available on the computer; input/output con-
`trolling means including a user interface; and program
`executing means for executing a predetermined pro-
`gram.
`
`In accordance with a second aspect of the
`[0034]
`present invention, there is provided an automotive com-
`puter system, comprising: an operating system that
`implements environment necessary for execution Of a
`program of a predetermined form; a CPU; an automo-
`tive information system having a plurality of information
`devices; and controlling means for controlling the auto-
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`EP 0 950 570 A2
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`motive information system.
`
`In accordance with a third aspect of the present
`[0035]
`invention, there is provided a method of controlling an
`automotive information system by using a computer
`having an operating system, comprising: causing the
`operating system to implement environment necessary
`for executing a program of a predetermined form; and
`causing the program to control the automotive informa-
`tion system.
`[0036]
`In the automotive information system, automo-
`tive computer system and the method of controlling an
`automotive information system in accordance with first
`to third aspect of the present invention, the computer
`used for controlling the automotive information system
`has a general-purpose OS that administrates the
`resources such as a CPU and memories of the compu-
`ter so as to permit full use of the ability of the computer.
`The general-purpose OS also provides a user-friendly
`standardized user interface which is easy to use and
`which has no dependency on the programs. Further, the
`general-purpose OS permits addition or modification of
`a program having a predetermined form, thus facilitating
`addition or modification of the functions to be performed
`by the computer. For these reasons, the general-pur-
`pose OS serves to facilitate the control of complicated
`automotive information system. At the same time, the
`computer having general-purpose OS and combined
`with automotive information devices enables the user to
`
`utilize various kinds of programs available on the com-
`puter and to handle various kinds of information by mak-
`ing use of the function of the automotive information
`device such as a car audio system.
`[0037]
`In a specific form of the present invention, an
`automotive information system comprises: a controlling
`computer having a CPU; a plurality of
`information
`devices; a first BUS corresponding to the form of the
`CPU of the computer; and a second BUS interconnect-
`ing the information devices of the automotive informa-
`tion system.
`[0038]
`In another form of the invention, an automotive
`information system comprises: a controlling computer
`having a CPU; a plurality of information device; a local
`BUS corresponding to the form of the CPU of the com-
`puter; and a PCI BUS interconnecting the information
`devices of the automotive information system.
`[0039]
`In these forms of the present invention, the
`automotive information system may comprise data form
`converting means for converting the form of data
`exchanged between the BUSes,
`[0040]
`The automotive information system of the
`present invention may further comprise a third BUS that
`connects the plurality of information devices in a daisy-
`chain fashion.
`
`The present invention also provides an auto-
`[0041]
`motive computer system, comprising: a computer hav-
`ing a CPU; an automotive information system having a
`plurality of information devices; a first BUS correspond-
`ing to the form of the CPU of the computer; and a sec-
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`ond BUS interconnecting the information devices of the
`automotive information system.
`
`Provided also by the present invention is an
`[0042]
`automotive computer system, comprising: a computer
`having a CPU; an automotive information system hav-
`ing a plurality of information devices; a local BUS corre-
`sponding to the form of the CPU of the computer; and a
`PCI BUS interconnecting the information devices of the
`automotive information system.
`[0043]
`The automotive computer system of any type
`stated above may further comprise data form converting
`means for converting the form of data to be exchanged
`between the BUSes.
`
`The automotive computer system may also
`[0044]
`comprise a third BUS for connecting the plurality of
`information devices of the automotive information sys-
`tem in a daisy-chain fashion.
`[0045]
`In accordance with a fourth aspect of the
`present invention, there is provided a method of control-
`ling an automotive information system including a plu-
`rality of information devices by using a computer having
`a CPU, comprising: causing the CPU to transmit and
`receive data through a first BUS corresponding to the
`form of the CPU; and causing the information devices to
`exchange data through a second BUS interconnecting
`the information devices.
`
`In the controlling method of the fourth aspect,
`[0046]
`as well as in the foregoing automotive information sys-
`tem and automotive computer system employing differ-
`ent BUSes,the CPU of
`the computer
`and the
`information devices use BUSes that are adapted to the
`CPU and the information devices, respectively. When
`data is exchanged between these different BUSes, con-
`version of the form of data is executed as necessary.
`Therefore, the CPU having high operation speed is not
`required to keep pace with operation cycles of the infor-
`mation devices that operate at much lower speeds than
`the CPU. Therefore, the CPU is allowed to quickly per-
`form complicated processings by,
`for example, effi-
`ciently making access to memories. Further, the risk of
`conflict between the data handled by the CPU and the
`data handled by the information devices, which may
`occur when a single BUS is used commonly both by the
`CPU and the information devices, can be avoided,
`whereby the computer and the information devices can
`operate smoothly without being interfered by each
`other.
`
`It is also possible to easily conduct multi-task
`[0047]
`operation such that, for example, the CPU executes a
`processing by using the BUS adapted to the CPU while
`audio signals are being reproduced by on informtion
`device such as a car audio system using the BUS inter-
`connecting the information devices. Further, replace-
`ment of
`the CPU can easily be made simply by
`changing the BUS to another type of BUS which is
`adapted to the new CPU, without requiring modification
`or change in the arrangement of the information devices
`and the BUS which interconnects these devices.
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`EP 0 950 570 A2
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`The daisy-chain type connection of the infor-
`[0048]
`mation devices, achieved by connecting these devices
`in a manner like a sweet-potato-vine, enhances the
`degree of freedom in the selection of locations of the
`information devices. This permits easier setting of the
`devices than in the case of a star-type connection in
`which long cables are concentrated to a central hub.
`This also affords simple and neat wiring layout, allowing
`easy modification and protective maintenance, as well
`as repair.
`
`In accordance with a fifth aspect of the present
`[0049]
`invention, there is provided an automotive information
`system, comprising: a plurality of devices for providing
`at least one of audio data and digital data; transmitting
`means for transmitting, in the form of digital signals, the
`audio data and digital data from the devices; processing
`means for processing the digital data and the audio data
`in the form of the digital signal; audio output means for
`outputting, in the form of analog signals, the audio data
`processed by the processing means; and digital output
`means for outputting the digital data processed by the
`processing means.
`[0050]
`This automotive information system may fur-
`ther comprise A/D conversion means for converting
`analog signals supplied from the devices into audio data
`in the form of digital signals.
`[0051]
`The plurality of devices may include a radio
`tuner and/or a microphone.
`[0052]
`In the automotive information system of the
`type described above, analog signals derived from the
`radio tuner or the microphone are converted into audio
`data in the form of digital signals, and the digital audio
`data thus obtained are digitally transmitted and proc-
`essed together with other digital data.
`[0053]
`The transmission means may include a PCI
`BUS. In such a case, the data is transmitted through the
`PCI BUS that interconnects the peripheral devices, so
`that various kinds of digital data an be unitarily adminis-
`trated. In addition, wider variety of devices can be incor-
`porated in the automotive information system when the
`PCI BUS is used.
`
`[0054] The transmitting means may also include data
`destination determining means which determines desti-
`nation to which the data is to be transmitted, based on
`the device by which the data is provided. Thus, the
`transmission means performs traffic control as to the
`source and destination of various data. A circuit such as
`
`ASIC performs this traffic control, thus facilitating uni-
`tary management of the data.
`[0055] The automotive information system of the fifth
`aspect may further comprise a digital sound processor.
`Since the audio data if analog is converted into digital
`signals, the audio data in the form of digital signals is
`conveniently processed by the digital sound processor.
`This permits various functions such as equalizing, vol-
`ume control, balancing and fading to be easily imple-
`mented in a contactless manner with high grade or
`quality.
`
`10
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`15
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`20
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`25
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`30
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`35
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`55
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`The audio output means may includes D/A
`[0056]
`conversion means for effecting D/A conversion to con-
`vert the processed audio data into analog signals, and
`an amplifier for enabling the analog signals to activate a
`speaker. In this case, the audio data is unitarily control-
`led in digital form and then converted into analog sig-
`nals, whereby the analog processing of the audio data
`is minimized, with the result that the audio characteristic
`is stabilized.
`
`[0057] The digital output means may include an oper-
`ation display section for outputting the processed digital
`data. This feature enables the user to easily operate the
`information device such as the car audio system, while
`monitoring characters and images formed of digital data
`and displayed on the operation display section.
`[0058] The automotive information system of the fifth
`aspect may further comprise connecting means £or
`connecting the plurality of devices of the automotive
`information system in a daisy-chain fashion.
`[0059]
`The daisy-chain type connection of the infor-
`mation devices, achieved by connecting these devices
`in a manner like a sweet-potato-vine, enhances the
`degree of freedom in the selection of locations of the
`information devices. This permits easier setting of the
`devices than in the case of a star-type connection in
`which long cables are concentrated to a central hub.
`This also affords simple and neat wiring layout, allowing
`easy modification and protective maintenance, as wall
`as repair.
`[0060] The arrangement may be such that the above-
`mentioned connecting means includes a USB, while the
`transmission means includes a PCI BUS.
`In this case,
`the automotive information system further comprises
`form conversion means for converting the audio data
`and the digital data transmitted through the USB into
`data of a form adapted for the PCI BUS.
`[0061]
`The USB provides a rather low transmission
`rate, although it permits daisy-link-type transmission.
`Transmission of data from the information devices is
`
`conducted by using this USB. The data transmitted
`through the USB is then subjected to a form conversion
`so as to be changed into data of a form that is suitable
`for transmission and processing through the PCI BUS
`which provides comparatively high transmission rate.
`It
`is thus possible to make an effective use of the merits of
`both types of BUSes, by virtue of the conversion of the
`data form.
`
`In the automotive information system of the fifth
`[0062]
`aspect, the plurality of devices may include at least one
`of a CD-BOM auto-changer for reading data from music
`CDs and CD-ROMs while changing the CD or the CD-
`ROM from one to another, an alarm system for security
`purpose, and an automotive telephone system.
`[0063] This automotive information system has a vari-
`ety of uses. For instance, it is possible to read from a
`CD-ROM various kinds of digital data to be used by the
`car navigation system. It is also possible that the secu-
`rity system informs the driver of any extraordinary event
`
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`11
`
`EP 0 950 570 A2
`
`12
`
`via the automotive mobile phone. In particular, a multi-
`function automotive information system can be imple-
`mented with a simple wiring layout, by employing the
`aforementioned daisy-chain type wiring connection.
`
`In accordance with the sixth aspect of the
`[0064]
`present invention, there is provided a method of control-
`ling an automotive information system having a plurality
`of devices, comprising the steps of: causing the plurality
`of devices to supply