Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Hirotsugu Kawada

Noboru Katta

Yuji Mizuguchi

Takahisa Sakai

Toshihiko Kurosaki

Nobuhiko Yasui

Yutaka Takahira

Makoto Tatebayashi

Shunji Harada

Susumu Ibaraki

Toshitomo Umei

Yoshihiro Mori

Osamu Shibata

Katsuhiko Miwa

Takashi Akita

Masaaki Takata

A data player for reading contents encrypted by a decoding key from a digital medium, and playing the encrypted contents by using the decoding key which is stored in a key storage unit, comprises: a key obtaining unit for performing mutual authentication with the key storage unit to obtain the decoding key stored in the key storage unit; a key holding unit for holding the decoding key; a playback state obtaining unit for monitoring the playback state of the digital medium; and a contents decoding unit for decoding the encrypted contents by using the decoding key. The decoding key is obtained by the key obtaining unit and stored in the key holding unit, and the encrypted contents read from the digital medium is decoded with the decoding key by the contents decoding unit to play the contents. The decoding key stored in the key holding unit is discarded according to the playback state of the digital medium which is obtained by the playback state obtaining unit.

Data player, digital contents player, playback system, data embedding apparatus, and embedded data detection apparatus

A data transmission system in which normal transmission can be performed irrespectively of the inserting orientation of a connector is provided. A transmitting device transmits to a receiving device a differential transmission signal including polarity decision data for deciding the polarity of the connector. Based on the polarity decision data included in the differential transmission signal transmitted from the transmitting device, the receiving device decides whether the polarity of the connector has been reversed or not. When it is decided that the polarity has not been reversed, the receiving device reads data from the differential transmission signal. When it is decided that the polarity has been reversed, the polarity of the differential transmission signal is reversed for data reading.

Data transmission system

A recording apparatus records movie content onto a DVD. The movie content is encrypted using a different encryption method depending on whether the DVD is intended for consumer use or industrial use. If the DVD is for consumer use, a VIDEO_TS directory is created on the DVD, and the encrypted movie content is recorded in the VIDEO_TS directory. If the DVD is for industrial use, a VIDEO_TS directory and an EWCPS_TS directory are created on the DVD, and the encrypted movie content and message data are recorded respectively in the EWCPS_TS directory and the VIDEO_TS directory. The message data indicates that the movie content cannot be played back by consumer DVD players.

Recording method and apparatus, optical disk, and computer-readable storage medium

A digital data transmission apparatus includes a transmitting end () that includes: a binary/quadrary conversion unit () for converting a data stream; a coding unit () for mapping converted data to be coded; a digital filter (); a D/A conversion unit (); a low-pass filter () for attenuating noises which are caused by folding distortion; a differential driver (); low-pass filters () and () for eliminating noises from differentially outputted signals; and a common mode choke coil () for eliminating common mode noises and outputting a resultant signal to a twisted pair cable (), and a receiving end () that includes: a low-pass filter () for eliminating noises from the twisted pair cable; a receiver (); an A/D conversion unit (); a digital filter (); an evaluation unit () for evaluating a signal level of a received signal; a decoding unit () for decoding the signal level into received data; and a synchronization unit () for generating a clock.

Digital data transmitter

A digital data transmission apparatus includes a transmitting end () that includes: a binary/quadrary conversion unit () for converting a data stream; a coding unit () for mapping the converted data to be coded; a digital filter (); a D/A conversion unit (); a low-pass filter () for eliminating a high-band signal; a differential driver () for inputting an analog signal that has passed through the low-pass filter into a twisted pair cable (), and a receiving end () that includes: a low-pass filter () for eliminating noises from both wires of the twisted pair cable; a receiver () for receiving the signals that have passed through the low-pass filter; an A/D conversion unit (); a digital filter (); an evaluation unit () for evaluating a signal level of a received signal; a decoding unit () for decoding the signal level into receipt data; and a synchronization unit () for generating a clock.

Digital data transmitter, transmission line encoding method, and decoding method

A ring-shaped network quickly performs initialization even when a plurality of data transmission apparatuses are connected thereto. Each data transmission apparatus outputs received data to a device connected thereto while performing establishment of clock synchronization based on the received data, and when synchronization is established, it resends the received data. Further, when synchronization of the connected device is established, it sends data supplied from the connected device. Further, a master data transmission apparatus outputs data at turn-on of power or immediately after reset, and a next-stage slave data transmission apparatus receives the data to establish synchronization, and resends the received data when synchronization is established. Thus, synchronization of all the data transmission apparatuses is established while making a round of this data, and then synchronization of devices connected to the respective data transmission apparatuses is established.

Ring network and data transmitter

An evaluation level setting method and a data reception apparatus in which the method is implemented accurately evaluate signal levels in multi-valued transmission for transmitting data while assigning one or more bits of data as one data symbol to a signal level. A data transmission apparatus outputs an initialization pattern signal at turn-on of power or after reset, and the data reception apparatus establishes clock synchronization on the basis of the received initialization pattern signal and starts data reception after setting of evaluation levels to be used for threshold evaluation of signal levels.

Judgment level setting method and data receiver

A first initialization pattern signal is a signal in which a maximum signal level and a minimum signal level appear alternately, and a second initialization pattern signal is a signal in which all signal levels appear in a predetermined arrangement. In a ring-shaped network including plural stages of data transmission apparatuses (), a transmission unit () of each data transmission apparatus outputs the first initialization pattern signal successively to a next-stage data transmission apparatus at turn-on of power or immediately after reset, and a reception unit () establishes clock synchronization on the basis of the first initialization pattern signal received. When synchronization is established in all of the data transmission apparatuses, the transmission unit () outputs the second initialization pattern signal successively to the next-stage data transmission apparatus, and the reception unit () sets evaluation levels for the respective signal levels on the basis of the received second initialization pattern signal, and transmission/reception of data is started when evaluation levels are set in all of the data transmission apparatuses.

Initializing method and data transmitter

A receiver includes a noise reduction circuit for eliminating noise from a differential signal transmitted through a differential transmission line, and a data recovery circuit for recovering data from a differential signal outputted from the noise reduction circuit. The noise reduction circuit includes common-mode chokes for reflecting common-mode noise superimposed on an input differential signal, and a common-mode noise reduction circuit for directing the common-mode noise reflected by the common-mode chokes to a low potential point of the common-mode noise reduction circuit.

Receiver

A communications system and a communications device are provided that can reduce the difference in data reaching time with a simple structure and can play audio without making listeners feeling strange. A communications device is coupled to a network and a device such as a CD player or the like. The communications device includes a network interface unit , a network controller communicating with the device and others, and a CPU controlling these components. Furthermore, the network interface unit , a transmission signal processing unit and a reception signal processing unit converts the data format appropriate for the network controller and the network , respectively. A transmission scheme determination unit determines the transmission scheme used among nodes. First and second switches and each have a contact A and a contact B, connecting either one of these contacts based on a control signal from the transmission scheme determination unit

Growing community of inventors

Sakai, Japan

Hirotsugu Kawada