Sony

Sony Corporation (ソニー株式会社 ,Sonī Kabushiki Gaisha?) is a multinational conglomerate corporation headquartered in Minato, Tokyo, Japan, and one of the world's largest media conglomerates with revenue exceeding US$99.1 billion (as of 2008).[1] Sony is one of the leading manufacturers of electronics, video, communications, video game consoles, and information technology products for the consumer and professional markets. Its name is derived from sonus, the Latin word for sound.[4]

Sony Corporation is the electronics business unit and the parent company of the Sony Group, which is engaged in business through its five operating segments—electronics, games, entertainment (motion pictures and music), financial services and other. These make Sony one of the most comprehensive entertainment companies in the world. Sony's principal business operations include Sony Corporation (Sony Electronics in the U.S.), Sony Pictures Entertainment, Sony Computer Entertainment, Sony Music Entertainment, Sony Ericsson, and Sony Financial Holdings. As a semiconductor maker, Sony is among the Worldwide Top 20 Semiconductor Sales Leaders. The company's slogan is Sony. Like no other.[5]

In 1945, after World War II, Masaru Ibuka started a radio repair shop in a bombed-out building in Tokyo. The next year, he was joined by his colleague Akio Morita and they founded a company called Tokyo Tsushin Kogyo K.K.,[6] which translates in English to Tokyo Telecommunications Engineering Corporation. The company built Japan's first tape recorder called the Type-G.[6]

In the early 1950s, Ibuka traveled in the United States and heard about Bell Labs' invention of the transistor.[6] He convinced Bell to license the transistor technology to his Japanese company. While most American companies were researching the transistor for its military applications, Ibuka looked to apply it to communications. Although the American companies Regency and Texas Instruments built the first transistor radios, it was Ibuka's company that made them commercially successful for the first time. In August 1955, Tokyo Telecommunications Engineering released the Sony TR-55, Japan's first commercially produced transistor radio.[7] They followed up in December of the same year by releasing the Sony TR-72, a product that won favor both within Japan and in export markets, including Canada, Australia, the Netherlands and Germany. Featuring six transistors, push-pull output and greatly improved sound quality, the TR-72 continued to be a popular seller into the early sixties.

In May 1956, the company released the TR-6, which featured an innovative slim design and sound quality capable of rivaling portable tube radios. It was for the TR-6 that Sony first contracted "Atchan", a cartoon character created by Fuyuhiko Okabe, to become its advertising character. Now known as "Sony Boy", the character first appeared in a cartoon ad holding a TR-6 to his ear, but went on to represent the company in ads for a variety of products well into the mid-sixties.[6] The following year, 1957, Tokyo Telecommunications Engineering came out with the TR-63 model, then the smallest (112 × 71 × 32 mm) transistor radio in commercial production. It was a worldwide commercial success.[6]

University of Arizona professor Michael Brian Schiffer, Ph.D., says, "Sony was not first, but its transistor radio was the most successful. The TR-63 of 1957 cracked open the U.S. market and launched the new industry of consumer microelectronics." By the mid 1950s, American teens had begun buying portable transistor radios in huge numbers, helping to propel the fledgling industry from an estimated 100,000 units in 1955 to 5,000,000 units by the end of 1968. However, this huge growth in portable transistor radio sales that saw Sony rise to be the dominant player in the consumer electronics field[8] was not because of the consumers who had bought the earlier generation of tube radio consoles, but was driven by a distinctly new American phenomenon at the time called rock and roll.

Sony's headquarters moved to Minato, Tokyo from Shinagawa, Tokyo around the end of 2006.

Direct Stream Digital

Direct-Stream Digital (DSD) is the trademark name used by Sony and Philips for their system of recreating audible signals which uses pulse-density modulation encoding, a technology to store audio signals on digital storage media which is used for the Super Audio CD (SACD).

The signal is stored as delta-sigma modulated digital audio, a sequence of single bit values at a frequency sampling rate of 64 times the CD Audio sampling rates of 44.1 kHz, for a rate of 2.8224 MHz (1 bit times 64 times 44.1 kHz). Noise shaping occurs by use of the 64× oversampled signal to reduce noise/distortion caused by the inaccuracy of quantization of the audio signal to a single bit. Therefore it is a topic of discussion whether it is possible to eliminate distortion in 1-bit Sigma-Delta conversion (see Audio Engineering Society Convention Paper 5395 in the External Links section below).

There has been much controversy between proponents of DSD and PCM over which encoding system is superior. Professors Stanley Lipshitz and John Vanderkooy from the University of Waterloo, in Audio Engineering Society Convention Paper 5395

(2001), stated that 1-bit converters (as employed by DSD) are unsuitable for high-end applications due to their high distortion. Even 8-bit, four-times-oversampled PCM with noise shaping, proper dithering and half data rate of DSD has better noise floor and frequency response. However, in 2002, Philips published a convention paper arguing against this in Convention Paper 5616

. Lipshitz and Vanderkooy's paper has been criticized in detail by Professor James Angus at an Audio Engineering Society presentation in Convention Paper 5619

. Lipshitz and Vanderkooy responded in Convention Paper 5620

.

Practical DSD converter implementations were pioneered by Ed Meitner, an Austrian sound engineer and owner of EMM Labs. Global DSD technology was developed by Sony and Philips, the designers of the audio CD. Philips' DSD tool division was transferred to Sonic Studio, LLC

in 2005 for on-going design and development.

DSD technology may also have potential for video applications. A similar structure based on pulse-width modulation, which is decoded in the same way as DSD, has been used in Laserdisc video.

Audio effects and amplification

PWM is sometimes used in sound synthesis, in particular subtractive synthesis, as it gives a sound effect similar to chorus or slightly detuned oscillators played together. (In fact, PWM is equivalent to the difference of two sawtooth waves. [1]

) The ratio between the high and low level is typically modulated with a low frequency oscillator, or LFO.

A new class of audio amplifiers based on the PWM principle is becoming popular. Called "Class-D amplifiers", these amplifiers produce a PWM equivalent of the analog input signal which is fed to the loudspeaker via a suitable filter network to block the carrier and recover the original audio. These amplifiers are characterized by very good efficiency figures (≥ 90%) and compact size/light weight for large power outputs.

Historically, a crude form of PWM has been used to play back PCM digital sound on the PC speaker, which is only capable of outputting two sound levels. By carefully timing the duration of the pulses, and by relying on the speaker's physical filtering properties (limited frequency response, self-inductance, etc.) it was possible to obtain an approximate playback of mono PCM samples, although at a very low quality, and with greatly varying results between implementations.

In more recent times, the Direct Stream Digital sound encoding method was introduced, which uses a generalized form of pulse-width modulation called pulse density modulation, at a high enough sampling rate (typically in the order of MHz) to cover the whole acoustic frequencies range with sufficient fidelity. This method is used in the SACD format, and reproduction of the encoded audio signal is essentially similar to the method used in class-D amplifiers.

The term low-frequency oscillation (LFO) is an audio signal usually below 20 Hz which creates a pulsating rhythm rather than an audible tone. LFO predominantly refers to an audio technique specifically used in the production of electronic music. The abbreviation is also very often used to refer to low-frequency oscillators themselves, which produce the effects explored in this article.

Power delivery

PWM can be used to reduce the total amount of power delivered to a load without losses normally incurred when a power source is limited by resistive means. This is because the average power delivered is proportional to the modulation duty cycle. With a sufficiently high modulation rate, passive electronic filters can be used to smooth the pulse train and recover an average analog waveform.

High frequency PWM power control systems are easily realisable with semiconductor switches. The discrete on/off states of the modulation are used to control the state of the switch(es) which correspondingly control the voltage across or current through the load. The major advantage of this system is the switches are either off and not conducting any current, or on and have (ideally) no voltage drop across them. The product of the current and the voltage at any given time defines the power dissipated by the switch, thus (ideally) no power is dissipated by the switch. Realistically, semiconductor switches such as MOSFETs or BJTs are non-ideal switches, but high efficiency controllers can still be built.

PWM is also often used to control the supply of electrical power to another device such as in speed control of electric motors, volume control of Class D audio amplifiers or brightness control of light sources and many other power electronics applications. For example, light dimmers for home use employ a specific type of PWM control. Home use light dimmers typically include electronic circuitry which suppresses current flow during defined portions of each cycle of the AC line voltage. Adjusting the brightness of light emitted by a light source is then merely a matter of setting at what voltage (or phase) in the AC cycle the dimmer begins to provide electrical current to the light source (e.g. by using an electronic switch such as a triac). In this case the PWM duty cycle is defined by the frequency of the AC line voltage (50 Hz or 60 Hz depending on the country). These rather simple types of dimmers can be effectively used with inert (or relatively slow reacting) light sources such as incandescent lamps, for example, for which the additional modulation in supplied electrical energy which is caused by the dimmer causes only negligible additional fluctuations in the emitted light. Some other types of light sources such as light-emitting diodes (LEDs), however, turn on and off extremely rapidly and would perceivably flicker if supplied with low frequency drive voltages. Perceivable flicker effects from such rapid response light sources can be reduced by increasing the PWM frequency. If the light fluctuations are sufficiently rapid, the human visual system can no longer resolve them and the eye perceives the time average intensity without flicker (see flicker fusion threshold).