Sony Corporation ('Sony') has developed 'single wire interface technology', a hybrid transmission technology which facilitates both data and power transmissions through a single cable.
This technology enables the internal wiring of a mobile device to be streamlined through a single cable (copper wire). Conventionally, the video, audio and control signals as well as the power transmission were spread out over several dozen cables within the movable mechanisms of mobile devices, such as hinges or rotating parts. Sony aims to promptly implement this technology to improve design flexibility, reliability and durability for mobile devices with movable mechanisms.

In order to swiftly begin practical implementation of this technology, Sony has teamed up with ROHM Co., Ltd. ('ROHM'), which has a track record in peripheral technologies, for the joint development and technical validation for the analog portion of the test chip.
Hereafter, Sony will grant ROHM a license for the IP of the digital portion of this newly-developed technology in order to advance the development of a single chip which includes both the analog and digital portions.

• *1Time division duplex and multiplex: A method of digital data transmission using time slot.
  It enables bi-directionally transmitting multi-type of data over a single cable.
• *2Multi-level encoding: Encoding from data bits to multi-level code.

Main points of development

1. Time division duplex and multiplex have enabled bi-directional transmission of multiple types of data over a single transmission cable
Sony developed a unique time division duplex and multiplex method that enable packets of data, including video (display, camera), audio, and control signals to be transmitted over a single cable. Furthermore, Sony has enabled the bi-directional transmission of different signals, such as display and camera signals, by incorporating a mechanism that retains individual synchronization.

2. Unique multi-level encoding technology has enabled higher transmission rates within the limited signal frequency bandwidth
The newly-developed hardware is composed of (1) a digital portion that performs multi-level encoding, (2) an analog portion that transmits and receives signals, and (3) another portion that combines signals with DC power or separates signals from DC power. A unique multi-level encoding that has no DC component enables both high speed transmission with limited frequency bandwidth and DC power supply on a single common cable.
Sony has demonstrated that high transmission speeds (940Mbps) can be achieved.

Technical specifications (tentative values) of the demonstration system

• Transmission signal
  : video (Display / Camera), audio, control signals
• Transmission speed
  : 940Mbps
• Power consumption
  : 10-80mW (0-940Mbps) during transmission, 0.3mW when on stand-by.^*3
• Power supply voltage for analog IC
  : 1.5V/3.0V
• Transmission distance
  : 60cm^*4
• Supplied current value
  : 600mA^*4
• Operating ambient temperature
  : -20 - +85°C

• *3excluding the digital section (FPGA)
• *4when using twin coaxial cable #36 with shields

A comparison with conventional technology

The wiring between the main body of a mobile phone and its display section includes display data, camera data, audio signals, various kinds of sensor data and control data, and a DC power supply. The table below presents a comparison of required wiring for conventional technology, and required wiring for the newly-developed 'single wire interface technology'.

The above estimates assume the following conditions.

• Screen display: WVGA resolution
  Built-in camera on display side: VGA resolution
• Includes audio and DC power wiring.
• Has controls for various sensors (two type) such as the touch panel sensors and receives data.
• Has 4 key switch data acquisition controls and 2 LED flashing controls.