U.S. patent number 3,891,810 [Application Number 05/392,370] was granted by the patent office on 1975-06-24 for headphone.
Invention is credited to Naotake Hayashi.
United States Patent |
3,891,810 |
Hayashi |
June 24, 1975 |
Headphone
Abstract
A headphone set held over the ears by a band worn on the head of
a user comprises a sound box surrounding each ear and mounting in
its front, an electro-acoustic transducer. This electro-acoustic
transducer has its axis inclined by a small angle from the vertical
to a line connecting each ear.
Inventors: |
Hayashi; Naotake (Zoshigaya,
Toshima-ku, Tokyo, JA) |
Family
ID: |
13920087 |
Appl.
No.: |
05/392,370 |
Filed: |
August 28, 1973 |
Foreign Application Priority Data
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Sep 1, 1972 [JA] |
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47-87623 |
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Current U.S.
Class: |
381/373;
381/354 |
Current CPC
Class: |
H04R
1/1008 (20130101); H04R 5/0335 (20130101) |
Current International
Class: |
H04R
1/10 (20060101); H04m 001/05 (); H04r 001/10 () |
Field of
Search: |
;179/156R,182R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cooper; William C.
Attorney, Agent or Firm: Sughrue, Rothwell, Mion, Zinn and
Macpeak
Claims
What is claimed is:
1. A headphone set including a pair of headphones adapted to fit
over the ears of a user and connected by a head band, each
headphone comprising:
a sound box having a front wall defining an opening therein, upper
and lower walls, an outer side wall, and a rear wall, the sound box
being adapted to fit over the ear of a user such that the inner
peripheral edges of the front wall, the rear wall, and the upper
and lower walls make intimate contact with the head and cheek of a
user, and
a generally planar electro-acoustic transducer mounted within the
front wall opening and having a perforated exterior face,
said electro-acoustic transducer having an axis generally
perpendicular to the plane of the transducer inclined outwardly
from the front-rear axis of the users head at an angle of between
20.degree. to 30.degree..
2. A headphone set as defined in claim 1 wherein the transducer
comprises a central, planar, vibratory membrane spaced from and
disposed between a pair of planar, perforated electrodes, one of
said electrodes constituting said exterior face of the
transducer.
3. A headphone set as defined in claim 2 further comprising a layer
of acoustically absorbent material covering the inner surfaces of
the upper, lower, outer, and rear walls, and an aperture defined in
the rear wall and extending through the layer of material.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a headphone set held over the ears by a
band worn on the head of a user, comprising a sound box surrounding
each ear and an electro-acoustic transducer mounted near each
ear.
2. Description of the Prior Art
Headphone sets can be used to listen to high-fidelity recordings in
a relatively easy manner irrespective of a listener's position and
attitude. As a result, various improvements have been proposed to
such headphones for hearing stereo recordings. However, a bare
headphone is merely a kind of electro-acoustic transducer which can
transmit communication signals, so that it is basically unsuitable
for hearing stereo or binaural music.
Heretofore it has been proposed to modify a headphone for the
purpose of hearing stereo or binaural music. For example, the
headphone has been screened from outside noises with the aid of a
sound box and so constructed that the sound produced by the
electro-acoustic transducer is not leaked out of the box. In
addition, it has been proposed to provide openings in the sound box
to cause the outside sound and the sound produced in the headphone
to pass through these openings to some extent.
Such an open type headphone has the advantage that outside sound
can enter into the headphone or the sound reproduced can be leaked
out to a certain degree, and as a result, natural and excellent
high-fidelity sound can be reproduced and heard compared to a
closed type headphone.
Conventional closed and open type headphones, however, have the
disadvantages that since the electro-acoustic transducers are held
over the ears on a line connecting each ear the sound waves issued
from the left and right channels are directly transmitted to the
ear-drums from the left and right on a line connecting each ear,
that both a plug type earphone adapted to be inserted into the ear
and a large type headphone surrounding the ear are closely fitted
into and surround the external ear path and hence a sound pressure
is subjected to the ear, that the headphone covers the ear in quite
unnatural manner, and that the stereo signals reproduced by
headphones are basically different from those transmitted from
speakers and the natural sound to be heard by each ear per se.
SUMMARY OF THE INVENTION
The inventor has found out that in case of hearing a musical
performance, for example, the music is picked up by a set of
microphones arranged at the left and right sides of a listener and
transmitted through left and right channels to electro-acoustic
transducers by which the music is reproduced. In hearing such music
with both ears at once, it is best to locate the speakers on lines
met at the position of the listener and making an angle of about
60.degree.. The invention is based on such recognition.
A feature of the invention is the provision of a headphone held
over the ear by a band worn on the head of a user comprising a
sound box open at its front and surrounding each ear, and an
electro-acoustic transducer set into the open front of the sound
box, the axis of the electro-acoustic transducer being inclined
outwardly by a small angle from the vertical to a line connecting
each ear.
Such an such improved headphone has a number of advantages. First,
it is easy to catch almost all of the sound waves produced by the
electro-acoustic transducer located in front of the ear and to
transmit these sound waves through the external ear-path to the
ear-drum. Secondly, the axial direction of the external ear-path is
approximately perpendicular to the incident direction of the sound
waves so that the listener can catch the sound waves transmitted
from the front. Third, the frequency characteristics, phase
characteristics, etc. of the sound wave can be perceived by the ear
in response to the complex configuration of the ear, and as a
result, the listener can hear the sound in an extremely natural
aural sense from acoustic, physiological and psychological points
of view. Finally, an ideal stereo sound can be heard without the
disadvantage that the sound passes through a line connecting each
ear.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawing:
FIG. 1 is a front view showing a headphone held over the ear by a
band worn on the head of a user according to the invention, partly
in section;
FIG. 2 is a plan view of FIG. 1, partly in section;
FIG. 3 is a front view showing a sound box of the headphone
according to the invention in an enlarged scale; and
FIG. 4 is a section along line IV--IV in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the embodiment shown in the drawings, a sound box 1 has such
dimensions that it can surround each ear 2 with spaces remaining
around the ear 2 so as not to deform the ear. The sound box 1 is
comprised of upper and lower walls 3, 4, a side wall 5 and a rear
wall 6. The opposite side of the side wall 5 is opened so as to
insert the ear 2 into the sound box 1 and make the end edges of the
respective walls contact the head and cheek of a user. As a result,
the user's ears are not subjected to any disagreeable sound
pressure. In addition, the front side which is in opposition to the
rear wall 6 is opened, and to this open front is secured an
electro-acoustic transducer 7. If the box 1 is constructed as
described above, some sound can leak out of the box with the
frequency characteristics of the electro-acoustic transducer 7 well
matched to the incident signal, and the low frequency band is
adjustable. The box 1 is provided with a lining 8 made of some
suitable sound absorbing material to prevent the high frequency
band from being irregularly reflected.
The present invention makes use of some suitable electro-acoustic
transducer 7. In the embodiment shown in the drawings, the
electro-acoustic transducer 7 is comprised of an electrostatic type
flat plate shaped electro-acoustic transducer comprising a
diaphragm 9 and fixed electrodes 11 arranged at each side of the
diaphragm 9 and spaced apart by means of spacers 10. Reference
numbers 12, 13 and 14 designate lead wires connected to the
diaphragm 9 and fixed electrodes 11, respectively. The
electro-acoustic transducer 7 is so dimensioned that a plane sound
wave can arrive at the ears 2 as a whole from the front.
The electro-acoustic transducer 7 is not limited to the above
described electrostatic type, but an electromagnetic type can also
be used. In this case, it is preferable to use a velocity type, for
example, an elliptic dynamic speaker.
In the present invention, the electro-acoustic transducer 7 is set
into the front of the sound box 1 such that the axis of the
electro-acoustic transducer 7 is inclined by a relatively small
angle .theta., for example, 20.degree. to 30.degree. from the
vertical line 15 against a line connecting each ear 2 as shown in
FIG. 2. This is because of the fact that if one wishes to hear the
stereo-performance through two speakers, these speakers are located
on lines met at the listener and symmetrically inclined by about
30.degree. from the center line of the speakers such that the sound
wave arrives from the front at each ear of the listener. The
invention is based on such a stereo listening principle and the
transducers 7 are set into the sound box 1 so that the transducer 7
is placed in front and inclined by about 20.degree. to 30.degree.
from the vertical line 15 against the line connecting each ear 2 as
shown in FIG. 2.
The rear wall 6 and its lining 8 may be provided with an aperture
18 for passing waves sound wave produced by the transducer 7. The
provision of the aperture 18 results in an increase of the loss in
the low frequency band, however, it prevents the sound from being
confined in the box 1. If the frequency characteristics of the
transducer 7 were flat in the open field, the sound box 1 would not
be required. But, the amplitude of the sound wave is liable to
become constant at a frequency lower than about 100 Hz. As a
result, in order to correct for such low frequency characteristics,
a totally enclosed type headphone is preferable. But, the use of
such a transducer makes it difficult to eliminate the reaction of
the sound pressure since the low frequency band causes resonation
in the sound box cavity. As a result, it is necessary to provide a
number of small holes in the box 1 or to provide the aperture 18 in
the rear wall so that very low frequency sound waves leak out and
any resonance is dampened.
In the present invention, it is possible to connect the inside of
each sound box with a sound path 19. In this case, the sound path
19 can be provided along or inside of a head band 20. The coupling
of the boxes through the sound path 19 enables the obtention of a
time difference and sound pressure difference simultaneously in
each box, thereby improving the stereo performance of the
headphone. If it is desired to listen to a binaural performance,
the sound path 19 must be closed.
Since directivity characteristics are broader at the medium and low
frequency bands, the headphone according to the invention may be
formed in a conventional manner so as to damp the high frequency
band. A portion of the lining 8 which is near the transducer 7 can
then be removed and a tweeter element, that is, a small loudspeaker
responsive only to the higher frequency band, may be set there so
as to secure almost the same effect by adjusting the sound
pressure.
A transducer 7 can also be set into the rear wall 6 so as to
provide a four channel headphone.
* * * * *