Patent Application
20070058821
The present invention relates to microphones, and, more particularly, to an automotive microphone assembly.
Today's automobiles are becoming more complex in a variety of ways. One of those ways is in the accommodation of electronic devices used by the driver. Some vehicles include the ability to connect to cellular phones, the ability to connect to computer networks, complex sound systems, and/or entertainment systems, for example. Another way that vehicles have become more complex involves the use of “convenience” technologies. For example, some vehicles have navigation systems and/or a voice recognition system such as may be used to command features of the vehicle, including but not limited to the sound system, as well as a speech recording system or an intercom system.
Yet another way in which vehicles have become complex involves electronic control of previously uncontrolled operations of the vehicle. Vehicle stability systems, traction control, hybrid engines, noise monitoring or compression, noise control, and control of the engine's valves are a few examples of such electronic controls. For example, to conserve the consumption of fuel, some manufacturers reduce the number of valves used to run the vehicle at somewhat constant highway speeds. Such reduction in the number of valves used does, however, result in additional engine noise. Thus, in addition to the electronics required to control the number of valves, an electronic system is used to reduce the noise level in the cabin of the vehicle when the number of valves used is reduced.
Because there has been a significant increase in the use of electronics in vehicles, there is concern with respect to the costs associated with such electronics. In addition, there are usually limitations as to the location and size of components added to a vehicle. Thus, it is desired to provide an electronic assembly that reduces the cost of the electronics and reduces the physical space required for the vehicle's electronics.
More than one of the types of electronic systems found in vehicles require the use of a microphone to pickup (detect) certain sounds. These systems include, but not are not limited to, telephony systems, voice recognition systems, speech recording systems, intercom systems, noise control systems, noise compression systems, and noise monitoring systems. Thus, it is desired to provide a microphone assembly that serves multiple systems in an automotive application, and, in particular, an assembly that serves both: (a) a telephony system, a voice communication system, a speech recording system, or an intercom system, and (b) the active noise control, noise compression, or noise monitoring system of an automobile. It is also desired that such an assembly be made of reasonably priced components, be easy to assemble, and permit for maintenance and repair of the components of the assembly.
The present invention comprises an microphone assembly. The invention accommodates more than one microphone system for support of multiple electronic systems in an automobile, thereby resulting in a space savings in the automobile and realizing cost savings, while maintaining acoustic integrity of the systems. The assembly is made of reasonably priced components, is easy to assemble, and permits for repair or replacement of the components thereof, or of the entire assembly.
In one embodiment, the automotive microphone assembly of the present invention comprises a first microphone, a second microphone, and a connection means for electrically connecting the first and second microphones to a first automotive system and a second automotive system, respectively. Each of the first and second automotive systems comprises one of the group consisting of a telephony system, a speech recognition, system, a speech recording system, an intercom system, a noise control system, a noise compensation system, or a noise monitoring system. If one of the first or second microphones comprises a directional microphone, the corresponding automotive system comprises one of the group consisting of a telephony system, a speech recognition system, a speech recording system, or an intercom system. If one of the first or second microphones comprises an omnidirectional microphone, the corresponding automotive system comprises one of the group consisting of a noise control system, a noise compensation system, or a noise monitoring system.
In another embodiment of the assembly of the present invention, the assembly includes a first microphone having first and second leads, a second microphone having first and second leads, and a connection means. The connection means includes a first input for electrical connection to the leads of the first microphone, a second input for connection to the leads of the second microphone, a first output electrically connected to the first input and for electrical connection to a first automotive system, and a second output electrically connected to the second input and for electrical connection to a second automotive system.
Electrical connections may be made by hardwiring, printed circuit board(s), connector(s), interconnect(s), cable(s), or any combination thereof. Disposed between the first input and first output and/or the second input and second output may be circuitry such as preamplification circuitry, bias circuitry, microphone filtering and/or processing circuitry (such as analog filtering, analog-to-digital conversion, signal-to-noise-ratio enhancement means, digital filtering, or digital processing), and/or the circuitry required for each of the first and second automotive systems.
In another embodiment, the assembly of the present invention includes microphone boot for receipt of a first microphone and a second microphone, a printed circuit board, an interconnect, and a housing for the microphone boot and the printed circuit board. The printed circuit board provides for electrical connection between the first and second microphones and the interconnect. The interconnect provides, generally, for electrical connection to external electronics. In one embodiment, the interconnect provides for electrical connection to the first and second automotive systems. In another embodiment, the printed circuit board provides for electrical connection of the first and second automotive systems (if such electronic resides on the printed circuit board) to other external electronics.
The housing comprises, in one embodiment, a top housing portion for placement over the top of the microphone boot and surrounding the sides of the microphone boot, and a bottom housing portion for placement of the printed circuit board, interconnection, and top housing therein. Alternately, the bottom housing portion could be formed for placement outside the side surfaces of the top housing.
The assembly of the present invention may also comprise an acoustic cloth for placement over the top of the microphone boot between the microphone boot and the top housing portion. Such an acoustic cloth serves to protect the first and second microphones from dust and other foreign matter, and provides some wind noise mitigation. The assembly may also include a gasket for placement over the top of the top housing portion. Such a gasket protect and/or separates the housing from any adjacent or proximate devices in the automobile.
The housing comprises at least two apertures on the top thereof to serve as waveguide openings for the waveguides of the first and second microphones. The housing also comprises at least one other aperture to allow the interconnect to connect to external electronics.
The present invention comprises an automotive microphone assembly. Referring now to
Each of first microphone 36 and second microphone 38 comprise a waveguide opening for receipt of acoustic signals to the first and second microphones 36 and 38, respectively. The waveguide opening of first microphone 36 resides on the side surface of first microphone 36 not shown in
According to the present invention, printed circuit board 42 provides: (1) a pre-amplified directional microphone signal that is used for voice pickup by a hands free telephony system, by an automatic speech recognition system, by a speech recording system, and/or by an intercom system; and (2) a pre-amplified omnidirectional microphone signal as an input to an active noise control system, a noise compensation system, and/or a noise monitoring system. An example of a schematic for printed circuit board 42 is illustrated in
Microphone boot 40, acoustic cloth 34, housing 22, and gasket 20 are provided to hold first microphone 36 and second microphone 38 in electrical contact with printed circuit board 42 and for installation of microphone assembly 10 into an automobile. Thus, the materials of microphone boot 40, acoustic cloth 34, housing 22, and gasket 20 are of the type used in prior art microphone assemblies holding only a single microphone to be placed in an automotive environment. For example, microphone boot 40 and housing 22 are comprised of a non-conductive material, such as plastic or elastomeric material such as rubber, and assists in providing an acoustical seal about first microphone 36 and second microphone 38. Similarly, bottom portion 14 (see
In the embodiment of
Referring now to
Also, as seen in the combination of
In addition, top portion 12 of assembly 10 contains apertures on the top thereof that serve as waveguides for proper transmission to first and second microphones 36 and 38, and, more specifically, waveguides for proper transmission to the waveguide openings of first and second microphones 36 and 38. In the embodiment of
It will be appreciated by those of skill in the art that the plurality of apertures through which the leads of first microphone 36 and second microphone 38 extend may comprise two apertures—one for the first and second leads of first microphone 36 and one for first and second leads of second microphone 38. There may also be one aperture for each such lead, or separate apertures for the leads of one of the microphones and a single aperture for the leads of the other microphone. There may also be only a single aperture through which both first microphone 36 and second microphone 38 extend and through which their respective leads are connected.
Referring now to
For directional microphone MIC1 and associated circuitry, transistors Q1A and Q2 form a high gain NPN Darlington pair. Transistor Q1B is used to form a complementary Darlington PNP/NPN configuration with first dual NPN Darlington pair. Standard Darlington pairs of NPN or PNP transistors and Complementary Darlington Pairs of NPN and PNP transistors are well-known. The three transistors Q1A, Q1B and Q2 configured as a Darlington/complementary Darlington configuration and form a very high open loop gain inverting amplifier. Typical open loop gain is on the order of 140 dB.
Feedback network C5 and R6 form a feedback impedance from output to input of the preamplifier. C1 and R11 form an input impedance of the amplifier. The impedance ratio of C5 and R6 divided by impedance of C1 and R11 set the closed loop gain of the microphone preamplifier for MIC1. In the embodiment of
Resistors R2 and capacitor C2 provide a stable DC bias voltage to operate MIC1. Resistor R1 is used to bias MIC1 from this bias voltage. The preamplifier is self biased from an external voltage and bias resistor, for example, 12 volts and 2K ohms. The ratio of resistor R6 to R7, along with the forward base emitter voltage drop of Q2 and Q1A, set the DC operating point of the microphone preamplifier for MIC1 when powered from external bias voltage of 12 volts through a 2K ohm resistor. A typical DC bias point is 6 volts.
Resistor R8 sets the bias current ratio of transistors Q1A and Q1B. Bias collector current of transistor Q1A is set at the base emitter forward voltage drop of transistor Q1B divided by resistance R8. Capacitors C6, C9, C4, C12, and C7 are provided to reduce susceptibility to pickup and demodulation of radio frequency interference. Resistor R9 is provided to prevent damage should the preamplifier for MIC1 be directly connected to 12 volts without a bias resistor. R9 also helps provide immunity to radio frequency interference. Output of the microphone preamplifier for MIC1 is typically −5 dBV/Pa.
As illustrated in
Resistor R13 sets the bias current ratio of transistors Q3A and Q3B. Bias collector current of transistor Q3A is set at the base emitter forward voltage drop of transistor Q3B divided by resistance R13. Capacitors C14, C15, C11, C19, and C20 are provided to reduce susceptibility to pickup and demodulation of radio frequency interference. Resistor R12 is set to 0 ohms for use with a protected 9V supply. Should the amplifier for MIC2 need to be powered from 12 V vehicle battery power, a small resistor should be used to provide protection from damage should the preamplifier be directly connected to 12 volts without a bias resistor. Output of the for omnidirectional microphone MIC2 is typically −13 dBV/Pa.
It will be appreciated by those of skill in the art that the present invention provides a compact assembly for microphones used to support multiple systems. In the particular instance illustrated in
It will also be appreciated by those of skill in the art that the preamplifier circuits of
It will be further appreciated that the microphone assembly of the present invention is comprised of reasonably priced components. It will be still further appreciated that the microphone assembly is easy to assemble. The components of the assembly are made to “fit” with respect to connecting components. It will be yet further appreciated that the microphone assembly of the present invention permits for repair or replacement of the entire assembly, or of components thereof. While the components may be repaired or replaced, it may be most cost effective to simply repair or replace the entire assembly.
It will also be appreciated by those of skill in the art that, while only two microphones were illustrated herein, the present invention is contemplated to be used to support more than two microphones and subsystems requiring such microphones. For example, a first directional microphone for connection with a telephony subsystem, a second directional microphone for connection with a voice recognition subsystem, and a first omnidirectional microphone for a noise monitoring subsystem can be held in a single microphone boot and supported by a single printed circuit board according to the principles taught by the embodiment illustrated herein.
It will also be appreciated by those of skill in the art that the printed circuit board present herein comprises a connection means between the first and second microphones and the first and second automotive systems, respectively. Other connection means are contemplated to be within the scope of the present invention, including but not limited to hardwired circuits, connectors, interconnects, cables, or any combination of wires, connectors, interconnects, cables, and printed circuit boards. Further, the connection means need not comprise the preamplifier circuits discussed in the embodiment of
It will be still further appreciated that variations of the combinations of microphones, connection means, and housings may achieve the result of an automotive vehicle module connecting a plurality of microphones with a plurality of automotive systems. In some instances, a housing may not be necessary, although for ease of assembly and to protect the module from the elements, a housing may be desired. While the embodiment of
It will be yet further appreciated that the automotive microphone assembly of the present invention is compact. The microphones of the present invention are co-located—in close proximity to each other. In one embodiment, the nearest points between the housings of the microphones are no further apart than 2 centimeters. Thus, the automotive microphone assembly does not consume a significant amount of space in the automobile, yet the acoustic integrity of the automotive system served by the microphone is maintained.
As used herein and in the claims, the term “automobile” and “automotive” includes any motorized vehicle that may include two or more of the telephony, speech recognition, speech recording, intercom, noise control, noise compensation, or noise monitoring systems. Thus, the terms “automobile” and “automotive” includes, but is not limited to, cars, trucks, sport utility vehicles, motorcycles, tractors and other farm equipment, cranes, front loaders and other construction equipment, and riding lawn mowers.
In view of the many possible embodiments to which the principles of this invention may be applied, it should be recognized that the detailed embodiments are illustrative only and should not be taken as limiting the scope of the invention. Rather, the invention comprises all such embodiments as may come within the scope and spirit of the invention and equivalents thereto.
