WO2025181928A1 - Speaker system for temple of spectacles - Google Patents

Abstract

The present invention provides a speaker system (PSZ earphone type) suitable for mounting on a spectacle temple. The speaker system includes a driver unit and a housing. The driver unit is disposed substantially parallel to the spectacle temple, and the inside of the housing is divided into a first space on the side close to the head and a second space on the far side from the head by a driver unit. A first sound hole is located on a line connecting the driver unit and an external earhole in the first space, and a second sound hole is located in a position close to the first sound hole in the second space.

Description

Glasses temple speaker system

The disclosed technology relates to a speaker system suitable for presenting audio content using VR glasses or AR glasses.
In this specification, a device that generates sound by vibrating a diaphragm using a magnet and coil or other means is called a "driver unit," and a device in which a driver unit is incorporated into a housing to obtain acoustic effects is called a "speaker system."

There are VR glasses and AR glasses that have speaker systems attached to the temples, providing users with audio content linked to video content. VR stands for Virtual Reality, and AR stands for Augmented Reality. Hereinafter, VR glasses, AR glasses, etc. will be collectively referred to as "VR glasses."
An example of VR glasses is shown in Figure 1. A speaker system is placed at a position 101 on the temples of the glasses, near the ears.
Unlike speaker systems that are worn in a way that blocks the ear canal, speaker systems placed on the temples of glasses are preferable as audio presentation devices for VR and AR because they put less strain on the ears even when worn for long periods of time. However, because the sound from the speaker system disperses into the air, there is an issue in that while the video content projected on the glasses is only visible to the user, the audio content coming from the speaker system is radiated into the surrounding area, exposing the information.

Earphones (Personalized Sound Zone earphones, hereinafter referred to as "PSZ earphones") have been proposed that can suppress sound leakage to the surroundings without blocking the external ear canal (Patent Document 1).
2A and 2B are schematic diagrams showing the speaker system of the PSZ earphone. (a) is a perspective view of the speaker system 2, (b) is a side view, and (c) is a diagram showing the speaker system 2 placed at the right ear.
Reference numeral 201 denotes a driver unit and 202 denotes a diaphragm. When a signal current flows through a coil (not shown), an induced magnetic field is generated, which interacts with the magnetic field of a magnet (not shown) to vibrate the diaphragm.
Sound waves are emitted from diaphragm 203 in both directions D1 (the front of the driver unit) and D2 (the back of the driver unit). The sound waves in the D1 direction and the D2 direction are in opposite phase to each other. Sound in the D1 direction will be called positive phase sound, and sound in the D2 direction will be called negative phase sound.
Reference numeral 203 denotes an opening (sound hole) that guides the sound of the positive phase from the speaker system 2 to the external ear canal 205. Reference numeral 204 denotes an opening (sound hole) that guides the sound of the negative phase to the outside of the speaker system 2.

If there is no opening 204, the sound waves emitted from the opening 203 will propagate to spaces other than the external ear canal, resulting in sound leakage to the surroundings.
If a sound wave of the same amplitude but in opposite phase is superimposed on the original sound wave, the original sound wave can be canceled or reduced. Therefore, when an opposite phase sound is emitted from opening 204, it interferes with a positive phase sound that propagates in directions other than the direction of the external ear canal from opening 203, and the two sounds cancel each other out in the vicinity of speaker system 2.
As a result, positive phase sound reaches the ear canal, but the sound from the speaker system 2 is cancelled or suppressed due to interference in the vicinity of the speaker system 2, realizing earphones that do not leak sound to the surroundings.

Japanese Patent Application Laid-Open No. 2023-182166

If PSZ earphones (speaker system 2 described above) are used in the speaker system of the VR glasses shown in Figure 1, it is expected that audio content will not leak to the surrounding area.
However, to effectively suppress sound leakage, it is necessary to carefully design the shape of the speaker system housing and the relative positions of the openings for the positive and negative phase sounds. However, existing PSZ earphones are not designed for mounting on eyeglass temples. Therefore, the structure (shape of the housing, position of the openings) of a PSZ earphone-type speaker system suitable for mounting on eyeglass temples is not known.

As a result of extensive research, the inventors have clarified the structure of a speaker system (PSZ earphone type) that is suitable for mounting on the temples of glasses.
The speaker system includes a driver unit and a housing. The driver unit is positioned approximately parallel to the temples of the glasses, and the interior of the housing is divided by the driver unit into a first space closer to the head and a second space farther from the head. In the first space, a first sound hole is located on a line connecting the driver unit and the external ear canal, and in the second space, a second sound hole is located in a position close to the first sound hole.

The disclosed technology provides a speaker system for eyeglass temples that effectively suppresses sound leakage to the surrounding area.

FIG. 1 is a diagram showing an example of VR glasses. A schematic diagram of the speaker system of a PSZ earphone. A diagram explaining a test method for determining the magnitude of sound leakage. 1A and 1B are side and perspective views of a square speaker system. Side, top, and bottom views of a square speaker system. FIG. 10 is a diagram showing an example of an anti-phase sound hole pattern used in measurement. FIG. 7 is a graph showing the frequency dependence of the sound pressure difference value in the 0° direction measured using the sound hole pattern shown in FIG. 6 . FIG. 7 is a graph showing the frequency dependence of the sound pressure difference value in the 90° direction measured using the sound hole pattern shown in FIG. 6. FIG. 10 is a diagram showing the directional dependency of sound pressure difference values by comparing the best pattern and the closed pattern. 10A and 10B are a perspective view of a circular speaker system according to a second embodiment worn on a head and a circular speaker system. FIG. 10 is a diagram showing the arrangement of anti-phase sound holes that were fabricated as a trial in order to find a suitable pattern for the anti-phase sound holes. FIG. 11 is a diagram for explaining that pattern d in FIG. 10 shows the best results. FIG. 10 is a diagram showing the arrangement of prototype anti-phase sound holes, which was fabricated to determine the position of the eccentric anti-phase sound holes. FIG. 13 is an overall view for explaining that pattern e in FIG. 12 shows the best results. FIG. 13 is an enlarged view for explaining that pattern e in FIG. 12 shows the best results. 10A and 10B are an exploded perspective view and a side view of a speaker system with a sound conduit according to a third embodiment worn on a head, and an exploded perspective view and a side view of the speaker system with a sound conduit. 10A and 10B are diagrams showing examples of changes in the length and angle of the sound guide tube and the opening position of the anti-phase sound hole. 14A and 14B are diagrams illustrating the results of measurements of three types of speaker systems with sound guide tubes and the pattern e of FIG. 13 according to the second embodiment. 10A and 10B are diagrams illustrating the relationship between the cross-sectional area of a sound guide tube and low-frequency boost.

Hereinafter, embodiments of the disclosed technology will be described in detail. Note that components having the same functions are assigned the same numbers, and duplicated descriptions will be omitted.
In the following embodiments, speaker systems were created by changing design parameters such as the driver unit of the speaker system, the shape and size of the housing, and the position and size of the sound holes that radiate positive and negative phase sounds, and sound was played back to measure the degree of sound leakage suppression, resulting in the discovery of a suitable structure.

[Test method]
First, a test method for determining the magnitude of sound leakage will be described with reference to Fig. 3. Fig. 3 shows the case where the right ear of a dummy head is used.
A test speaker system 302 is placed near the ears of a dummy head 301 (where the speaker system will be located when VR glasses or the like are worn).
An ear-position microphone 303 is placed in the external ear canal of the dummy head 301 .
Leakage sound is measured by arranging leakage sound microphones 304 concentrically on a plane at the same height as the ears. The leakage sound microphones 304 are placed 150 mm from the center of the driver unit's diaphragm. With the front as seen from the dummy head as the 0° direction, 18 microphones are placed at 15° intervals from -45° to 210°.
The sound pressure difference value = sound pressure measured with the leak sound microphone - sound pressure measured with the ear-position microphone was recorded. In other words, the smaller the sound pressure difference value, the better the sound leakage was suppressed.

This concludes the explanation of the [test method].

[First embodiment]
The first embodiment employs a square driver unit and discloses an optimal arrangement of sound holes in a housing that houses the square driver unit. The speaker system of the first embodiment is hereinafter referred to as a "square speaker system."

First, the above-mentioned [Test Method] was carried out by simulation.
Figure 4(a) is a side (top) view of the square speaker system viewed from the top of the head. The interior of the housing of the square speaker system is divided into two by the driver unit 201. Of these, the front side (D1) of the driver unit 201 will be called the normal phase space (401), and the rear side (D2) will be called the reverse phase space (402). Figure 4(a) shows how the volume of the reverse phase space 402 is changed.

Figure 4(b) is a perspective view of the square speaker system viewed from the ear canal side. The hole through which positive phase sound is emitted from the positive phase space 401 is called the positive phase sound hole (403). Figure 4(b) shows how the number of positive phase sound holes is changed.

Fig. 5(a) is a side view of the square speaker system viewed from the side of the head, showing the side surface of the housing that forms the anti-phase space 402. Holes are drilled in the shaded area of the housing side. The holes through which anti-phase sound is emitted from the anti-phase space 402 are called anti-phase sound holes (501). Fig. 5(a) shows the arrangement of anti-phase sound holes 501 of various shapes and positions.
FIG. 5B is a side (bottom) view of the square speaker system as seen from the jaw side of the dummy head, showing the state in which an anti-phase sound hole 501 is provided on the bottom surface of the housing.
FIG. 5C is a top view of the square speaker system, showing the state in which an anti-phase sound hole 501 is provided on the top surface of the housing.

We conducted approximately 20 acoustic simulation patterns by changing the combinations of "volume of the anti-phase space,""number of normal phase sound holes," and "pattern of anti-phase sound holes," and obtained the following results.
(1) It is better to reduce the volume of the reversed phase space as much as possible.
(2) Two positive phase sound holes are better than one (the wider the opening area, the better).
(3) The anti-phase sound hole pattern produces good results when it is opened only on the sides, not on the top or bottom, and the openings are located closer to the top of the head and closer to the ears.

Based on the above results, various speaker systems were prototyped and sound pressure difference values were measured using a dummy head, etc.
FIG. 6 shows an example of the antiphase sound hole pattern of the speaker system used in the measurement, and (d) shows a pattern (closed pattern) in which no antiphase sound holes are drilled.
7A and 7B show the frequency dependence of the sound pressure difference between the 0° and 90° directions for patterns a, b, c, and d. It was found that pattern b had the greatest effect in suppressing sound leakage.
Figure 8 shows the polar patterns (directional dependence of sound pressure difference values) for the best pattern b and the sealed pattern d. Each polar pattern is the measurement result when sounds of 100.26 Hz, 199.87 Hz, 399.47 Hz, 800.13 Hz, 1000 Hz, and 2000 Hz are reproduced using a square speaker system. Note that the "90° direction" in Figure 8 is reversed from Figure 3.
It was found that the square speaker system with pattern b reduces sound leakage in all directions, especially in the forward (0°) direction, compared to the square speaker system with a sealed pattern.

This concludes the description of the first embodiment.

Second Embodiment
The second embodiment employs a circular driver unit and discloses an optimal arrangement of sound holes in a housing that houses the circular driver unit. The speaker system of the second embodiment is hereinafter referred to as a "circular speaker system."

Figure 9(a) shows eyeglass temples equipped with a circular speaker system 90 according to the second embodiment attached to a dummy head 301. Figure 9(b) is a perspective view of the circular speaker system 90 viewed from the ear canal side. The circular speaker system 90 has a positive phase space 901 and a negative phase space 902 separated by a circular driver unit, a positive phase sound hole 903 that radiates sound in the positive phase space from the housing, and a negative phase sound hole 904 that radiates sound in the negative phase space from the housing.

In the second embodiment, we first considered suitable patterns for the anti-phase sound holes. Figure 10(a) shows a state in which a small hole (24.6 ^mm2 ) is placed in the center of the side of the anti-phase space 902 that is perpendicular to the temporal region. Similarly, (b) shows a state in which a medium hole (49 ^mm2 ) is placed in the center of the same side, (c) shows a state in which a large hole (75.4 ^mm2 ) is placed in the center of the same side, (d) shows a state in which a small hole (24.6 ^mm2 ) is placed near the front of the same side, and (e) shows a state in which four divided holes (6.6 ^mm2 x 4) are placed on the same side.

Figure 11 shows the frequency dependence of the sound pressure difference values measured for patterns a, b, c, d, and e. The measurements were taken at a 90° angle. Pattern d showed the best results at frequencies between 2 kHz and 3 kHz. This suggests that it may be possible to control the cancellation frequency by adjusting the distance between the positive and negative phase sound holes and the resonance point.

Therefore, based on the pattern in Figure 11 (d), the position of the anti-phase sound holes was changed and the sound pressure difference value was measured. As shown in Figure 12, a circular speaker system was prototyped with eccentric small holes (anti-phase sound holes) arranged as shown in (a) to (h), and the sound pressure difference value was measured. Specifically, for example, in (a) the sound holes were arranged in the front direction of the dummy head, in (c) in the direction of the top of the dummy head, and in (b) at a 45° angle between (a) and (c).

Figure 13A shows the frequency dependence of the sound pressure difference values measured for patterns c, d, e, and f. The measurement position was in the 90° direction. Figure 13B is an enlarged view of a frequency around 3 kHz. Figure 13B shows that pattern e (with the anti-phase sound hole eccentrically positioned closer to the back of the head) achieves significant suppression up to the highest frequency, and this position provides the optimal balance between the positive and negative phase sound holes.

This concludes the description of the second embodiment.

[Third embodiment]
If the speaker system is far from the ear canal, it is difficult to generate sound pressure, which leads to sound leakage. Therefore, as a third embodiment, a structure that uses a sound guide tube to deliver sound directly to the ear is disclosed. The speaker of the third embodiment will be referred to as a "speaker with a sound guide tube" below.

Fig. 14(a) shows a state in which eyeglass temples equipped with a speaker system with a sound conduit 140 according to the third embodiment are attached to a dummy head 301. Fig. 14(b) is an exploded view of the speaker system with a sound conduit. Here, an example using a circular driver unit is shown.
14(c) is a cross-sectional view. Circular driver unit 1407 is built into speaker system 140 with sound conduit, and forms positive phase space 1401 and negative phase space 1402. Positive phase conduit 1405 expands positive phase space 1401 and has positive phase sound hole 1403 on the side opposite to where driver unit 1407 is located. Negative phase conduit 1406 expands negative phase space 1402 and has negative phase sound hole 1404 on the side opposite to where driver unit 1407 is located.

We prototyped various speakers with sound conduits using the angle and length of the sound conduit and the position of the anti-phase sound hole as parameters, and measured the sound difference value. Note that the "sound conduit angle" is defined as 0° when the line connecting the driver unit and the positive phase sound hole is vertical, and 90° when it is horizontal.
FIG. 15(a) shows an example of a prototype in which the length of the sound guide tube is changed.
FIG. 15(b) shows an example of a prototype in which the angle of the sound guide tube is changed.
FIG. 15(c) shows an example of a prototype in which the positive-phase conduit and the negative-phase conduit are of different lengths.
FIG. 15(d) shows an example of a prototype in which the opening position of the antiphase sound hole is changed.

As a result of measuring the sound pressure difference values for various prototype speaker systems, the best results were obtained with the following structure.
(1) The sound guide tube extends from the driver unit toward the external auditory canal at an angle (approximately 30°).
(2) The length of the reversed-phase conduit is made longer than that of the normal-phase conduit. In the test, favorable results were obtained with a prototype with a normal-phase conduit of 20 mm and a reversed-phase conduit of 30 mm.
(3) The anti-phase sound hole is opened perpendicular to the line connecting the external ear canal and the driver unit.
However, requirement (3) above provided the best results, and a high sound leakage suppression effect was also confirmed with a structure that met requirements (1) and (2) and had the anti-phase sound hole opened in a direction parallel to the line connecting the external ear canal and the driver unit.

FIG. 16 shows the results of the sound pressure difference test, showing the largest sensitivity difference.
Graph A shows a prototype with a conduit angle of 30°, a positive phase conduit length of 10 mm, a negative phase conduit length of 10 mm, and the positive phase sound hole and negative phase sound hole facing the same direction.
Graph B shows a prototype with a conduit angle of 30°, a positive phase conduit length of 20 mm, a negative phase conduit length of 30 mm, and the negative phase sound hole opened at a right angle to the positive phase sound hole.
Graph C shows a prototype with a conduit angle of 30°, a positive phase conduit length of 30 mm, a negative phase conduit length of 30 mm, and the positive phase sound hole and negative phase sound hole facing the same direction.
For comparison, graph D shows the results of measurements taken for pattern e in FIG. 13 in the circular speaker system of the second embodiment.
Graph B gives the best results, achieving a greater overall sensitivity difference than Graph D. Sound leakage is significantly suppressed, especially in the frequency range of 3kHz-10kHz.

Furthermore, we found that in a speaker system with a sound duct, it is possible to boost the low frequencies as a secondary acoustic effect by changing the opening area of the duct.
The measurement results are shown in Figure 17. Graphs E, F, and G show the frequency dependence of sound pressure measured with an ear-positioned microphone when the cross section of the sound conduit was changed to 2mm x 12mm, 2mm x 9mm, and 2mm x 6mm, respectively. In all prototypes, the length of the sound conduit was 30mm, and the positive and negative phase sound holes were oriented in the same direction.
It can be seen from FIG. 17 that a smaller cross-sectional area increases the acoustic mass and tends to lower the lowest resonance frequency (so-called f ₀ ).

This concludes the description of the third embodiment.

[supplement]
In the third embodiment, a circular driver unit is used, but in a speaker system with a sound guide tube, the structure of the sound guide tube is important, and the driver unit may be square.
In addition, in the third embodiment, it was stated that favorable results were obtained with a prototype having a positive-phase conduit length of 20 mm and a negative-phase conduit length of 30 mm, but the conduit lengths can be changed to suit the design characteristics of the device.

1 VR glasses 101, 2, 302, 90, 140 Speaker system 201, 1407 Driver unit 202 Diaphragm 203, 403, 903, 1403 Positive phase sound hole 204, 501, 904, 1404 Negative phase sound hole 205 External ear canal 301 Dummy head 303 Ear position microphone 304 Leakage sound microphone 401, 901, 1401 Positive phase space 402, 902, 1402 Negative phase space 1405 Positive phase conduit 1406 Negative phase conduit

Claims (7)

A speaker system arranged on the temples of eyeglasses worn on the head,
Equipped with a driver unit and housing,
The driver unit is disposed approximately parallel to the temples of the glasses,
The inside of the housing is divided by the driver unit into a first space that is closer to the head and a second space that is farther from the head,
the first space has a first sound hole on a line connecting the driver unit and the external ear canal,
The second space has a second sound hole located in the vicinity of the first sound hole. 2. A speaker system according to claim 1,
The driver unit is rectangular,
The second sound hole is opened in a direction perpendicular to the driver unit at a position close to the first sound hole and close to the direction in which it will hit the top of the head. 3. The speaker system according to claim 2,
The volume of the second space is smaller than the volume of the first space,
The speaker system is characterized in that the first space is substantially perpendicular to the direction in which the temples extend and also has a sound hole in the direction in which the temples contact the chin. 2. A speaker system according to claim 1,
the driver unit is circular,
The second sound hole is opened in a direction perpendicular to the driver unit at a position close to the first sound hole. 2. A speaker system according to claim 1,
the first space includes a first duct that extends along a line (a first direction) connecting the driver unit and the external ear canal,
the second space includes a second conduit extending along the first conduit,
The speaker system, wherein the second pipe is longer than the first pipe. 6. A speaker system according to claim 5,
The speaker system according to claim 1, wherein the second sound hole is opened in the first direction at an end of the second duct that is closer to the external ear canal. 6. A speaker system according to claim 5,
The speaker system according to claim 1, wherein the second sound hole is opened in a direction perpendicular to the first direction at an end of the second duct that is closer to the external ear canal.