Electrical audio signal processing systems and devices – Circuitry combined with specific type microphone or loudspeaker
Reexamination Certificate
2000-06-07
2003-04-15
Harvey, Minsun Oh (Department: 2644)
Electrical audio signal processing systems and devices
Circuitry combined with specific type microphone or loudspeaker
C381S191000, C381S191000, C381S172000, C381S173000, C381S174000, C381S151000
Reexamination Certificate
active
06549631
ABSTRACT:
DESCRIPTION
The present invention relates to a pressure transducing assembly according to the preamble of claim 1.
It is known in the art that having measurement data in digital form offers the advantage over the well-known analogue representation of data to show very low additional signal noise and distortions in particular during the steps of further processing.
Picking-up measurement data from pressure measurements, for example in the infrasonic, ultrasonic or audible range, using conventional pressure transducing assemblies or digital microphones leads to signal distortions and noise impacts which are—in accordance with the tremendous low noise level capabilities of present data/sound playback devices—in some cases disturbing.
Therefore, digital pressure pick-up devices/microphones have been developed with the aim to generate a digital equivalent of the analogue pressure-/sound signal at a very early stage of the signal processing chain.
In the known art digital pressure pick-up devices or microphones comprise an audio or pressure transducer on the basis of an analogue pressure/audio signal conversion process. These audio/pressure transducers of the conventional art contain at a first stage a transducer section which converts the mechanical analogue pressure value into an analogue electrical equivalent.
A microphone/pressure transducer generally produces a low-level electrical signal in response to that audible sound/pressure levels around the microphone/pressure transducer. This particular low-level electrical signal is then transmitted or conducted along an electrical pathway or cable to subsequent processing apparatuses—for example, a digital signal processing device such as an audio mixing and control section—where it is converted into a digital signal for further processing.
Along the particular electrical pathway the low-level electrical signal is affected by external noise and interference processes during transmission along the cable. Further, analogue amplification—usually in the range of 40-60 db—introduces noise and distortions.
Therefore, known digital microphones/pressure transducing assemblies utilize an analogue amplification stage immediately after the mechanical-to-electrical conversion of the sound/pressure so as to increase the signal-to-noise ratio.
Immediately after amplification an analogue-to-digital converter is connected which produces a digital equivalent to the analogue and amplified measuring signal.
Although known devices for modulating or converting analogue electrical signals do not produce further analogue noise per se, conventional electric negative feedback loops, for example in 1-bit analogue/digital converters, interact with further analogue equipment and in particular with difference/summation amplifiers which do introduce additional analogue noise to the sound/pressure signal in the feedback process, e.g. of a conventional delta-sigma modulator or transducer. Analogue amplification by itself is much worse than A/D conversion noise.
It is therefore an object of the present invention to improve the signal-to-noise ratio performance of known sound/pressure transducing assemblies.
This particular object is achieved with a pressure transducing assembly according to the generic part of claim 1 with the characterizing features of claim 1.
It is a further object of the present invention to reduce the parts count and assembly cost and size of sound/pressure transducing assemblies. Advantageous embodiments of the inventive transducing assembly are covered by the dependent claims.
State of the art pressure transducing assemblies for converting a received pressure into a digital pressure signal in general comprise pressure transmitting means, pressure receiving processing means and pressure signal processing means.
In accordance with the present invention the pressure transmitting means is adapted to receive a first or environmental mechanical pressure from an environment and to transmit said first pressure to said pressure receiving and processing means. Said pressure receiving and processing means is adapted to generate a second or internal mechanical pressure therein in accordance with said received first pressure and further to process said second pressure. Said pressure receiving and processing means comprises pressure signal generating means which is adapted to generate a first or analogue pressure signal being representative for said second pressure. Additionally, said pressure receiving and processing means has pressure compensating means to receive a pressure compensation signal and to generate an additional pressure within said pressure receiving and processing means in particular according to said analogue pressure compensation signal as to compensate said second pressure at least in part. The pressure signal processing means is adapted to receive and process said first analogue pressure signal. Furthermore, said pressure signal processing means has negative feedback capabilities to generate said analogue pressure compensation signal at least based on said received analogue pressure signal. Finally, said pressure signal processing means is adapted to generate a digital pressure signal having an integer number of bits and being representative at least for said internal pressure and/or said first or environmental pressure and to provide at least said digital pressure signal as an output signal.
A basic idea of the present invention is to exchange noise introducing analogue electronic elements of conventional sound/pressure transducing assemblies, in particular the analogue input amplifier together with the difference/summation-amplifier of negative-feedback capability, by means of mechanical components.
Therefore, the inventive pressure transducing assembly does not contain a mechanical-to-electrical signal transducer in connection with the amplifier and difference amplifier as an input stage. Instead, a received pressure signal from an environment is transmitted to pressure processing means, which indeed further processes the pressure, i. e. the physical or mechanical entity itself instead of its electrical equivalent as done by the conventional art.
The pressure processing means comprises a pressure signal generating means, which converts the pressure/sound—being processed—into an equivalent analogue electrical signal.
The equivalent electrical signal is then further processed in conventional manner by pressure signal processing means. Such a pressure signal processing means utilizes an integrator and a comparator to produce a digitized equivalent of the analogue electrical pressure signal. According to the negative-feedback capability of the pressure signal processing means the digital signal is fed back to the mechanical acting pressure receiving and processing means by using a digital-to-analogue converter which re-converts an integrated and digitized pressure signal into an analogue pressure compensation signal, the latter being impressed to the provided pressure compensating means of said pressure receiving and processing means. In particular 1-bit—i. e. on or off—or multi-bit digital-to-analogue conversion is applied.
The pressure compensating means then produces an additional pressure within said pressure receiving and processing means so as to compensate the pressure in said pressure receiving and processing means at least in part. Therefore, a mechanical realization of a negative-feedback control loop is realized by exchanging a conventional electrical amplifying and comparing stage by means of mechanical analogues. Therefore, no additional analogue electrical noise is introduced and accordingly, the output signal of the pressure signal processing means can have a better signal-to-noise ratio compared with the purely electrical or electronical realizations of sound/pressure transducing devices.
These conventional sound/pressure transducing devices are often known as delta-sigma transducers or modulators, and they are also called balanced charge transducers or modulators as they perform in part an electrical compensation of the
Frommer William S.
Frommer & Lawrence & Haug LLP
Grier Laura A.
Harvey Minsun Oh
Sony International (Europe) GmbH
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