Patent Application
20060133629
The present invention relates generally to audio monitors and, more particularly, to an in-ear monitor.
In-ear monitors, also referred to as canal phones and stereo headphones, are commonly used to listen to both recorded and live music. A typical recorded music application would involve plugging the monitor into a music player such as a CD player, flash or hard drive based MP3 player, home stereo, or similar device using the monitor's headphone jack. Alternately, the monitor can be wirelessly coupled to the music player. In a typical live music application, an on-stage musician wears the monitor in order to hear his or her own music during a performance. In this case, the monitor is either plugged into a wireless belt pack receiver or directly connected to an audio distribution device such as a mixer or a headphone amplifier. This type of monitor offers numerous advantages over the use of stage loudspeakers, including improved gain-before-feedback, minimization/elimination of room/stage acoustic effects, cleaner mix through the minimization of stage noise, increased mobility for the musician and the reduction of ambient sounds.
In-ear monitors are quite small and are normally worn just outside the ear canal. As a result, the acoustic design of the monitor must lend itself to a very compact design utilizing small components. Some monitors are custom fit (i.e., custom molded) while others use a generic “one-size-fits-all” earpiece.
Prior art in-ear monitors use either diaphragm-based or armature-based receivers. Broadly characterized, a diaphragm is a moving-coil speaker with a paper or mylar diaphragm. Since the cost to manufacture diaphragms is relatively low, they are widely used in many common audio products (e.g., ear buds). In contrast to the diaphragm approach, an armature receiver utilizes a piston design. Due to the inherent cost of armature receivers, however, they are typically only found in hearing aids and high-end in-ear monitors.
Diaphragm receivers, due to the use of moving-coil speakers, suffer from several limitations. First, because of the size of the diaphragm assembly, a typical earpiece is limited to a single diaphragm. This limitation precludes achieving optimal frequency response (i.e., a flat or neutral response) through the inclusion of multiple diaphragms. Second, diaphragm-based monitors have significant frequency roll off above 4 kHz. As the desired upper limit for the frequency response of a high-fidelity monitor is at least 15 kHz, diaphragm-based monitors cannot achieve the desired upper frequency response while still providing accurate low frequency response.
Armatures, also referred to as balanced armatures, were originally developed by the hearing aid industry. This type of driver uses a magnetically balanced shaft or armature within a small, typically rectangular, enclosure. As a result of this design, armature drivers are not reliant on the size and shape of the enclosure, i.e., the ear canal, for tuning as is the case with diaphragm-based monitors. Typically, lengths of tubing are attached to the armature which, in combination with acoustic filters, provide a means of tuning the armature. A single armature is capable of accurately reproducing low-frequency audio or high-frequency audio, but incapable of providing high-fidelity performance across all frequencies. To overcome this limitation, armature-based in-ear monitors often use two, or even three, armature drivers. In such multiple armature arrangements, a crossover network is used to divide the frequency spectrum into multiple regions, i.e., low and high or low, medium, and high. Separate armature drivers are then used for each region, individual armature drivers being optimized for each region. Unfortunately, as armatures do not excel at low-frequency sound reproduction, even in-ear monitors using multiple armatures may not provide the desired frequency response across the entire audio spectrum. Additionally, the costs associated with each armature typically prohibit the use of in-ear monitors utilizing multiple armature drivers for most applications.
Although a variety of in-ear monitors have been designed, these monitors do not provide optimal sound reproduction throughout the entire audio spectrum. Additionally, those monitors that achieve even a high level of audio fidelity are prohibitively expensive. Accordingly, what is needed in the art is an in-ear monitor that achieves the desired response across the audio spectrum at a reasonable cost. The present invention provides such a monitor.
The present invention provides an in-ear monitor for use with either a recorded or a live audio source. The disclosed in-ear monitor combines a single diaphragm driver and a single armature driver within a single earpiece, thereby taking advantage of the capabilities of each type of driver. Preferably, the diaphragm is used to reproduce the lower frequencies while the higher frequencies are accurately reproduced by the armature driver. Such a hybrid design offers improved fidelity across the desired frequency spectrum and does so at a reduced cost in comparison to multiple armature designs. In addition to the two drivers, the in-ear monitor of the invention includes means for splitting the incoming signal into separate inputs for each driver. Typically this function is performed by a passive crossover circuit although an active crossover circuit can also be used. In at least one embodiment, acoustic dampers are interposed between one or both driver outputs and the eartip.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.
As previously noted, circuit 105 of in-ear monitor 100 sends input signals to both armature 107 and diaphragm 109. In at least one embodiment of the invention, circuit 105 is comprised of a passive crossover circuit. This passive crossover divides the incoming audio signal into a low-frequency portion and a high-frequency portion. The low-frequency portion is routed electrically to diaphragm 109 and the high-frequency portion is routed electrically to armature 107. Passive crossover circuits are well known in the industry and as the present invention is not limited to a specific crossover design, additional detail will not be provided herein. In an alternate embodiment, circuit 105 is comprised of an active crossover circuit.
The invention can use any of a variety of armature and diaphragm designs and is not limited to a single design for either. As armature and diaphragm drivers are well known by those of skill in the art, additional details will not be provided herein. In at least one embodiment of the invention, armature 107 utilizes a split coil design, thus allowing in-ear monitor 100 to achieve a more uniform frequency response while also providing an impedance that is suitable for use with a greater variety of consumer audio products.
Eartip 313 is designed to fit within the outer ear canal of the user and as such, is generally cylindrical in shape. Eartip 313 can be fabricated from any of a variety of materials. Preferably eartip 313 is fabricated from a compressible material (e.g., elastomeric material), thus providing a comfortable fit for the user. As shown in the exploded view of
Although sound delivery assembly 311 can utilize a single piece design, in the preferred embodiment of the invention sound delivery assembly 311 is comprised of a boot 405 and a damper housing 407. Boot 405 and damper housing 407 can be held together using any of a variety of means, including pressure fittings, bonding, interlocking flanges, etc. Preferably the means used to attach boot 405 to damper housing 407 is such that the two members can be separated when desired. In at least one embodiment of the invention, captured between members 405/407, and corresponding to driver outputs 409/411, is a pair of dampers 413/415. Alternately, a single damper can be used, corresponding to either driver output 409 or driver output 411. The use of dampers allows the output from the in-ear monitor 300 in general, and the output from diaphragm 301 and armature 305 in particular, to be tailored. Tailoring may be used, for example, to reduce the sound pressure level overall or to reduce the levels for a particular frequency range or from a particular driver. Damper housing 407 also includes a pair of conduits 501/503 that deliver the sound from the drivers through dampers 413/415 (if used) to eartip 313. Although the preferred embodiment keeps the sound conduits separate throughout housing 407, in an alternate embodiment sound conduits 501/503 converge in a “Y” fashion to a single output conduit (not shown).
As previously noted, there are numerous minor variations of the present invention. For example,
As will be understood by those familiar with the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/639,407, filed Dec. 22, 2004, the disclosure of which is incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 60639407 | Dec 2004 | US |
