CN113473332A

CN113473332A - Miniature electroacoustic transducer with digital interface

Info

Publication number: CN113473332A
Application number: CN202110706723.3A
Authority: CN
Inventors: 卢明辉; 张胜; 谢海圣; 郁晓君
Original assignee: Suzhou Acoustic Industrial Technology Research Institute Co ltd
Current assignee: Suzhou Acoustic Industrial Technology Research Institute Co ltd
Priority date: 2021-06-24
Filing date: 2021-06-24
Publication date: 2021-10-01

Abstract

The invention discloses a miniature electroacoustic transducer with a digital interface, which comprises: the micro-speaker is internally provided with a digital-to-analog conversion module; the main chip is connected with the digital-to-analog conversion module in the micro loudspeaker through an external terminal; the main control chip of the invention does not have the condition of digital-to-analog conversion, and adopts a system of a digital micro-speaker, so that the product form is more compact; the introduction of the digital micro-speaker can be: more digital main control chips are adapted, particularly, the chips without high-precision digital-to-analog conversion are adapted, and the overall cost of the scheme is reduced.

Description

Miniature electroacoustic transducer with digital interface

Technical Field

The invention relates to a miniature electroacoustic transducer with a digital interface, belonging to the technical field of audio equipment.

Background

With the popularization of audio products and the explosion of new technological industries. Wireless, intelligent and networking are becoming new trends in audio product development. These trends have changed the form of audio end products dramatically, and at the same time, they must have profound effects on audio components, the most significant of which is digitization. The miniature electroacoustic transducer is one of the important components of the audio component, and the digital design conforming to the audio development trend will become the cornerstone of the development and innovation of the future audio equipment.

The traditional electroacoustic transducer is a physical analog device generally as the name implies, and converts one analog physical quantity into another physical analog quantity; in the context of an electroacoustic transducer, the interconversion of electrical energy and acoustic energy is the main component, usually the device that converts electrical energy into acoustics is called a loudspeaker; and the device that converts acoustic energy into electrical energy is called a microphone. Although the electro-acoustic, electro-acoustic transducer accomplishes the mutual conversion of the acoustic physical quantity and the electric physical quantity. But it mainly aims at analog electric quantity, and because the analog electric quantity can not be directly received by the chip, it usually needs to add an additional AD, DA conversion link in the process of using. While a few chips provide an interface for directly receiving analog electrical signals, they are typically only simple digital-to-analog (analog-to-digital) interfaces that do not provide the digital electrical signals required for professional electro-acoustic processing. For chips with high-precision AD and DA functions, the price is usually high. If the acoustic signal has been digitized, the signal can be processed directly without digital-to-analog conversion. Besides the advantage of saving intermediate links, the digitization has the advantages of better anti-interference performance, better dynamic range and the like compared with the analog signal.

In view of the above considerations, acoustic-electric transducers represented by MEMS microphones have provided interfaces for directly converting acoustic quantities into digital electrical quantities. The MEMS microphone can directly convert the acoustic quantity into a PDM signal and transmit the PDM signal to a chip with a PDM digital interface, so that an intermediate AD conversion link is omitted. The elimination of the analog-to-digital conversion link not only saves the cost of the corresponding chip, but also saves the peripheral circuit required by the corresponding function. So that the product can be made more compact. In view of such a consideration, MEMS microphones are widely used in thin and lightweight cellular phones and in-ear microphones which require high size.

Today's miniature electro-acoustic transducers are still usually traditional devices for converting analog electrical quantities into analog acoustic quantities. The product typically needs to contain a digital to analog conversion section. And because the distinguishable acoustic frequency of human ears is between 20Hz and 20KHz, the plate-level noise in low-frequency bands in the product is easy to interfere with the electrical signals before electro-acoustic conversion, thereby deteriorating the audio playback effect.

To comply with the large trend of intelligence and to reduce the complexity of audio systems, more and more acoustic components are digitized. Such as digital audio power amplifiers, PDM microphones. Most of the present digital electroacoustic transducers or digital loudspeakers are usually medium-sized loudspeaker systems. In the micro-speaker link, the analog electroacoustic transducer is mainly used at present.

The intelligent digital acoustic equipment uses an analog electroacoustic transducer, and a main chip of the intelligent acoustic equipment is required to provide high-precision DA conversion capability, or an analog-to-digital conversion chip with a high-precision DA conversion function is introduced.

Digital chips with high precision DA capability are often expensive due to the particularities in the design: the on-chip design of the chip is usually a pure digital gate circuit design, the DA involves an analog part (digital-to-analog conversion), and the difficulty is greatly increased when the digital and analog parts need to be considered at the same time in the stage of involving the chip with a high-precision DA function.

If an external DA chip is adopted, the method has the following main application scenes for the micro loudspeaker: ear phones or hearing aids, the product size of which is limited to the size of the ear canal. The introduction of an external DA necessarily results in an increase in the size of the product, and in the case of a given ear canal size, it necessarily has a negative effect on the other functions of the device.

In addition, digital micro-speakers have advantages over analog micro-speakers in terms of signal integrity and interference immunity (audio frequency band). Since an electroacoustic transducer needs to convert electrical energy into mechanical/acoustic energy. The conversion usually requires the provision of ampere force or maxwell stress by means of a magnetic field. In the process of transduction, taking a moving iron unit as an example, low-frequency electromagnetic waves in an audio frequency band can be generated, and because the action waveband of the electromagnetic waves is the same as that of an analog electroacoustic transducer, positive feedback is easy to generate in acoustic amplification applications such as hearing aids. The digital transducer is usually in a synchronous type of 48KHz, and the digital signal is usually in the MHz level and is different from the low-frequency electromagnetic wave interference frequency band, so that the problems are not easy to occur.

Disclosure of Invention

The invention aims to provide a miniature electroacoustic transducer with a digital interface, which solves the defects of the prior art.

A digitally interfaced miniature electroacoustic transducer comprising:

the micro-speaker is internally provided with a digital-to-analog conversion module;

and the main chip is connected with the digital-to-analog conversion module in the micro loudspeaker through an external terminal.

Further, the interface of the external terminal is a digital interface.

Furthermore, the digital interface comprises a power line interface, a ground line interface, a signal clock interface, a synchronous clock interface and a signal interface.

Further, the external terminal is integrated within the micro-speaker.

Further, the micro-speaker includes a static magnet, an armature, a diaphragm, and a coil; the static magnet is arranged on the side portion of the armature, the coil is arranged on the armature and connected with an external terminal, and the armature is provided with a guide pin which is connected with the vibrating diaphragm.

Furthermore, two groups of static magnets are arranged on two sides of the armature respectively.

Compared with the prior art, the invention has the following beneficial effects: the main control chip of the invention does not have the condition of digital-to-analog conversion, and adopts a system of a digital micro-speaker, so that the product form is more compact;

the introduction of the digital micro-speaker can be: more digital main control chips are adapted, particularly, the chips without high-precision digital-to-analog conversion are adapted, and the overall cost of the scheme is reduced.

Chip design manufacturers can concentrate on the design of the high-speed digital gate circuit part and share the design difficulty of the scheme.

The digital-analog part is arranged in the micro loudspeaker, so that the design of the audio electromagnetic compatibility part can be improved, and the audio playback precision is improved.

Since the digital electric signal to the acoustic signal are all provided by the micro-speaker manufacturer, as shown in the structure diagram five: the structure is uniform. Unified and stable digital interfaces can be provided for manufacturers of different analog acoustic path design capabilities.

Drawings

FIG. 1 is a schematic diagram of a prior art balanced armature electroacoustic speaker;

FIG. 2 is a prior art internal structure diagram;

FIG. 3 is a connection diagram of a prior art external chip and moving-iron unit;

FIG. 4 is a schematic structural view of the present invention;

FIG. 5 is a schematic view of the interior of the structure of the present invention;

in the figure: 1. a static magnet; 2. an armature; 3. vibrating diaphragm; 4. a coil; 5. an external terminal; 6. a digital-to-analog conversion module; 7. and (6) guiding the needle.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

As shown in fig. 1, an external device supplies an analog voltage to the moving-iron unit through a terminal 5, which is a typical moving-iron configuration. Current enters the coil 4 through 5 and converts the voltage into current. A magnetic field will be generated by the passage of current through the solenoid structure of the coil 4. Since the acoustic signal is an alternating signal, the magnetic field generated by the coil 4 is also alternating. Because the armature 2 is usually a magnetic polarization material, an alternating magnetic field is amplified through the armature 2, the armature with alternating magnetic charges vibrates up and down at the balance position under the action of the armature 1, and the armature 2 is connected with the armature 3 through the guide pin and finally drives the armature 3 to vibrate and sound.

In the above-described conventional structure, an external device or chip directly supplies an analog voltage. The connection between the external chip and the moving iron unit is shown in fig. two and fig. three. Figure two shows the connection of a main chip without an internal DA conversion module to the micro-speaker. The output of the main chip is a digital signal expressed by D, and the digital control signal of the chip is converted into an analog control signal meeting the audio frequency requirement through an intermediate digital-to-analog conversion module; and the third figure shows the connection between a main control chip containing internal digital-to-analog conversion and the micro-speaker, and the micro-speaker directly receives the analog electric signal output by the chip due to the existence of the internal digital-to-analog conversion module.

As shown in fig. 4-5, the technical solution of the present invention discloses a digital interface miniature electroacoustic transducer, comprising:

the micro-speaker is internally provided with a digital-to-analog conversion module 6;

the main chip is connected with a digital-to-analog conversion module 6 in the micro loudspeaker through an external terminal 5; wherein the external terminal 5 is integrated within the micro-speaker, making the micro-speaker compact;

the main chip directly transmits the digital signal to the micro loudspeaker, and for the chip, the micro loudspeaker does not need any digital-to-analog conversion module and completes digital-to-analog conversion and electroacoustic transduction;

in this embodiment, the interface of the external terminal 5 is a digital interface, the external terminal 5 is changed from an original analog interface to a digital interface, the analog interface is usually a positive and negative binding post for a single signal, and the digital signal is usually a plurality of signals, such as a power line interface, a ground line interface, a signal clock interface, a synchronous clock interface, and a signal interface.

As shown in fig. 5, the micro-speaker includes a static magnet 1, an armature 2, a diaphragm 3, and a coil 4; the static magnet 1 is arranged on the side of the armature 2, the coil 4 is arranged on the armature 2 and is connected with an external terminal 5, the armature 2 is provided with a guide pin 7, the guide pin 7 is connected with the vibrating diaphragm 3, compared with the traditional analog moving iron unit, a digital-to-analog conversion module 6 is added in the static magnet, and the current of the coil 4 is supplied by the digital-to-analog conversion module 6. Two groups of static magnets 1 are arranged and are respectively arranged at two sides of the armature 2.

The main control chip of the invention does not have the condition of digital-to-analog conversion, and adopts a system of a digital micro-speaker, so that the product form is more compact;

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims

1. A digitally interfaced miniature electroacoustic transducer, comprising:

the micro-speaker is internally provided with a digital-to-analog conversion module (6);

and the main chip is connected with a digital-to-analog conversion module (6) in the micro loudspeaker through an external terminal (5).

2. The digitally interfaced miniature electroacoustic transducer of claim 1 wherein the interface of the external terminal (5) is a digital interface.

3. The digitally interfaced miniature electroacoustic transducer of claim 1 wherein said digital interface comprises a power line interface, a ground line interface, a signal clock interface, a synchronous clock interface and a signal interface.

4. The digitally interfaced miniature electroacoustic transducer of claim 1 wherein the external terminal (5) is integrated within a micro-speaker.

5. The digital-interfaced miniature electroacoustic transducer of claim 1 wherein said micro-speaker comprises a static magnet (1), an armature (2), a diaphragm (3) and a coil (4); the static magnet (1) is arranged on the side portion of the armature (2), the coil (4) is arranged on the armature (2) and connected with an external terminal (5), the armature (2) is provided with a guide pin (7), and the guide pin (7) is connected with the vibrating diaphragm (3).

6. The digital interfaced miniature electroacoustic transducer of claim 1 wherein said magnetostatic iron (1) is provided in two groups, one on each side of said armature (2).