JP2002536899A - Headphones - Google Patents

Abstract

(57) [Summary] A headband having an ear speaker (3) including a sound source in the form of a rigid lightweight panel (5) and a vibration exciter (6) for applying a bending wave to the panel to generate an acoustic output. Headphone (1) comprising (2).

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD [0001] The present invention relates to headphones. More particularly, the present invention relates to headphones comprising flexural panel shaped loudspeakers, such as, for example, distributed mode acoustic radiators of the general type described in International Patent Application WO 97/09842.

BACKGROUND OF THE INVENTION Conventional headphones use coherent, generally piston-moving sound sources. These have significant proximity effects and generally represent a high risk of placing the transducer at the entrance of the ear canal. It is difficult to predict or control the actual frequency response at the ear. Known ribbon and electrostatic flat headphones are cumbersome and costly.

(Disclosure of the Invention) According to the present invention, there is provided a headphone including a sound source in the form of a resonant panel, and conversion means for applying a bending wave to the panel to generate an acoustic output. The sound source may be in the form of a distributed mode acoustic radiator. The headphones preferably include a pair of distributed mode acoustic radiators.

[0004] The or each distributed mode acoustic radiator may comprise a rigid lightweight panel with a cellular core sandwiched between opposed skins.

[0005] The transducer for applying the bending wave to the radiator may be in the form of an electrodynamic inertial element.

[0006] Headphones made using distributed mode acoustical panels offer additional diffuse radiation patterns from large radiation areas, in addition to the potential for low cost, light weight, and thin configurations.
It also reduces the effects of standing waves on the head and proximity problems. Wearing on the head is much less important for good sound quality.

For this implementation, a thin panel designed to provide good distributed mode excitation over a wide frequency range is used and mounted on an elastic support, which with a defined minimum flex mode. , Near field, generally 30Hz to 20kHz
smooth the audible frequency band up to z. This is achieved by using a small electrodynamic transducer with low coil inductance.

[0008] For low cost, or even in disposable applications, distributed mode acoustic panels can be made with card-based reinforced structures driven by suitable mechanically compatible low cost piezoelectric transducers. it can. Similar structural materials can be used for headbands, resulting in an ultra-lightweight structure. The present invention is illustratively shown in the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1 and FIG. 2, a headphone device (hereinafter, referred to as “headphone”) (
1) In general, in the conventional configuration, an inverted U-shaped elastic padded member (2) is generally formed.
To form a headband having an ear speaker (3) supported on the free ends of the legs of the headband. Further, generally, a lead wire (4) connects an ear speaker to an output terminal of an audio amplifier (not shown) as in the related art. According to the invention, each ear loudspeaker comprises a resonant acoustic radiator, comprising a rigid lightweight panel diaphragm (5) and a vibration exciter (6) attached to the diaphragm. A bending wave is applied to resonate the panel to provide an acoustic output. International Patent Application WO 97/09842 describes a suitable distributed mode resonant bending wave acoustic radiator.

In the embodiment shown in FIG. 1, each pair of earphones is interleaved with a suitably small exciter arranged to drive the panel at a predetermined off-center position to provide good coupling to the mode distribution. A free-supporting resonance panel with physical parameters selected for the modal frequency to be applied.

A typical headband serves to attach the headphone assembly to the head, and a cable is provided to supply an audio signal to each channel exciter, which audio signal is typically, for example, stereo. This is a channel signal. For maximum efficiency, the panels are typically 50mm x 70mm or 50mm x 56mm in size, but may be smaller or larger depending on design constraints such as price, size, quality and bandwidth. , The panel is located approximately centered over the ear.

From FIG. 2, the panel (5) is supported by an elastic peripheral support (8) in a casing or housing (7), such as molded plastic, and comprises a sound attenuating material (10).
) Form a filled cavity (9). The housing has a projection or extension (11) for receiving the exciter (6). The panel (5) can be optimally covered by an acoustically transparent cover or grill. The panel (5) may be surrounded by a cushion (12) to improve user comfort. The casing or housing (7) is shown as closed, but may optionally be open.

FIG. 3 shows the casing or housing (7) of the embodiment of FIGS.
An embodiment of an ear speaker (3) replaced by an open frame (14) is shown, the open frame (14) supporting a panel (5) on a resilient peripheral support (8) and of the panel (5). Each side is covered by an acoustically transparent cover or grill (13) supported on a frame (14). In the configuration of the headphones (1) shown in FIG. 4, each ear speaker (3) has a housing or casing (17) for supporting the resonance panel (5) and the exciter (6), and the housing (17) 2 is similar to FIG. 2 but surrounds the panel (5) and projects into the panel inner side (15) to form an outlet (16) that is aligned with the user's ear canal. That is, the housing projection (15) forms a duct (18) with the inwardly facing surface of the panel (5), which sends acoustic energy from the entire panel to the outlet. In this connection, the output from the flexural wave panel is incoherent, unlike the coherent output from the earspeaker moving in the piston motion, so that there are problems associated with sending coherent sound to the ear canal. Note that this is prevented.

As mentioned above, the headphone of FIG. 5 uses a resilient support (8) to connect a panel (5) having a vibration exciter mounted on the panel to apply a bending wave to the panel to generate an acoustic output. An ear speaker (3) having a housing (27) for supporting a frame (14) supported thereby is provided. In this case, however, the housing (27) forms a duct (18) on the outer side of the panel (5), which ends at an outlet (19) which opens to the surrounding air. The duct is intended to load the panel with sound output from the entire outer surface of the panel (5) so as to increase the sound output entering the user's ear from the inner surface of the panel.

In the headphone embodiment of FIG. 6, the ear speaker (3) has a relatively large housing (37) intended to seal the user's ear with a cushion (12) to create a closed system.

In the headphone of FIG. 7, for example, the above-mentioned pair of ear speakers (3) is attached to each end of the headband (2) by a support member (20), and the posture of the support member (20) is the head. Adjustable for the band. Each of the pair of ear speakers (3) is attached to a hinge member (21), which in turn is attached to the member (20), and the earpiece is used to optimize the perceived sound quality of the user. The position and posture with respect to the ear can be adjusted. Also,
The ear speaker can slide along the support member (20) to change the attitude of the ear speaker. For this purpose, the member (21) is slidable on the member (20).

FIG. 8 is a diagram showing possible positions of the vibration exciter (6) on the panel (5) as taught generally in WO 97/09842. A point near the center represented by A is the most efficient, but a position near the end represented by C and taught in WO99 / 37121 shows good perceived sound quality.

Studies have shown that, of the two known methods of driving the local acoustics of the ear, pressure-driven and speed-driven, the speed method is more characteristic of natural perception and longer listening time with headphones. There is an advantage in reducing fatigue in certain ears. The market popularity of so-called "open air" headphones, such as made by Sennheiser in Germany, proves the appeal of a speed-driven design that does not use a steady pressure closing the ears compared to traditional types that require a tight seal Is what you do. Near center actuation for the flex wave panel will provide a combination of pressure and velocity sound energy at the ear entrance. When high sound quality is the goal, efficiency is not important because the amplifier output and magnet strength are inexpensive, and in any case the power level required by the headphones is several orders of magnitude lower than that required by loudspeaker applications, and therefore the loudspeaker A 1 watt requirement for the speaker's perceived volume level could be equivalent to just 10 mW for headphones, and a feature of the present invention is to minimize the pressure contribution and reduce the speed of the modal interleaved resonant panel. The point is to maximize the driving portion. Use exciters at end or near-end positions selected for good mode coupling, but where the balance or selection of positions is chosen to favor uniformity rather than absolute efficiency This allows the dominant bending wave to traverse the panel with little or no planar contribution and pass smoothly near the ear canal, thus providing the desired velocity drive equivalent to the ear sound field. Can be excited.

Since the sound field is actually quite diffuse due to the complex and almost random mode resonances that exist above the area of the panel, the acoustic coupling of the panel to the ear depends on the conventional coherent piston used in headphones. Most of the usual cavity and boundary resonance effects caused by the placement of the moving speaker components are prevented. Compared to the prior art, coherent sound sources driven in the standing wave mode do not occur in the area between the new headphone and the ear.

At the same time as the panels are smaller and the mounting / boundary conditions are favorable, many panel materials and constructions are available, and compliant polymer foaming over all or part of the perimeter This can be realized by using a resin support. Good results are obtained with monolithic and composite panel constructions, and metal can be used with relatively good boundary conditions for relatively small panels, e.g.
. An aluminum alloy of 15 mm to 0.8 mm, or copper, tin, zinc or the like can be used. In addition to various polymers such as polycarbonate and polystyrene, a monolith bonded with a carbon fiber resin is also effective from 0.8 mm to 0.1 mm. The efficiency requirements are not high and a wide variety of exciters can be used with pole diameters from 9 mm to 19 mm depending on the required bandwidth and volume.

When the exciter is mounted in position C, it is desirable to provide local mass attenuation of the panel, as taught in WO 99/37121. Experiments have shown that corner position B gives unsatisfactory results.

FIG. 9 shows a panel made of an aluminum plate and the frequency of a suitable exemplary ear speaker having the exciter mounted in position C of FIG. 8 and the mass attenuation of the panel as taught in WO 99/37121. It is a graph which shows a response.

In other words, the present invention provides a new type of headphone that avoids the problems of the piston motion element without being expensive like an electrostatic headphone.

[Brief description of the drawings]

FIG. 1 is a perspective view of a headphone device.

FIG. 2 is a sectional view of the headphone device of FIG. 1;

FIG. 3 is a cross-sectional view of another embodiment of the headphone device, similar to FIG. 2;

FIG. 4 is a sectional view of another embodiment of the headphone device, similar to FIG. 2;

FIG. 5 is a sectional view of another embodiment of the headphone device, similar to FIG. 2;

FIG. 6 is a sectional view of still another embodiment of the headphone device, similar to FIG. 2;

FIG. 7 is a plan view of another embodiment of the headphone device.

FIG. 8 is a diagram showing possible positions of a vibration exciter on a bending wave panel.

FIG. 9 is a graph of measured frequency response of a preferred headphone device.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID , IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72 ) Inventor Morecroft Dennis UK Cambridgeshire PEE 29 3 Cudie Huntingdon Hartford Road 18 F-term (reference) 5D005 BA01 BA07 BD13 5D016 EC04 EC23 FA01

Claims (9)

[Claims] 1. A headphone comprising: a sound source in the form of a rigid and lightweight panel; and a vibration exciter that applies a bending wave to the panel to generate an acoustic output. 2. The headphone according to claim 1, further comprising a pair of ear speakers facing each other. 3. The headphone according to claim 1, wherein the rigid lightweight panel is an aluminum plate. 4. A headphone according to claim 1, wherein the vibration exciter is in the form of an electrodynamic inertial element. 5. The headphone according to claim 2, wherein the ear speaker includes a housing forming an acoustic duct. 6. The headphones of claim 5, wherein the acoustic duct has an outlet intended to align with a user's ear canal. 7. The headphone according to claim 5, wherein the acoustic duct is intended to load the panel with the acoustic energy from the panel. 8. The apparatus according to claim 2, further comprising a headband, wherein the ear speaker is mounted on the headband so that a posture can be adjusted with respect to a user's ear. The headphones according to any one of the preceding claims. 9. The rigid lightweight panel according to WO97 / 09842 or WO9 / 09842.
The headphone of claim 1, wherein the headphone is a distributed mode acoustic radiator taught in 9/37121.