Speaker system for temple of spectacles

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

[0001] The disclosed technology relates to a speaker system suitable for presenting audio content with VR glasses or AR glasses. In this specification, a device that generates sound by vibrating a diaphragm with a magnet and coil or other means is referred to as a "driver unit," and a device in which a driver unit is incorporated into a housing to obtain an acoustic effect is referred to as a "speaker system."

[0002] VR and AR glasses feature speaker systems mounted on the temples, providing users with audio content linked to video content. VR stands for Virtual Reality, and AR stands for Augmented Reality. Hereinafter, VR and AR glasses will be collectively referred to as "VR glasses." Figure 1 shows an example of VR glasses. The speaker system is mounted on the temples at position 101, near the ears. Unlike speaker systems that are worn to block the ear canal, temple-mounted speaker systems are preferable as audio presentation devices for VR and AR because they place 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 a problem in that while the video content projected on the glasses is only visible to the user, the audio content played from the speaker system is emitted into the surrounding area, exposing information.

[0003] Earphones (Personalized Sound Zone earphones, hereafter 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). Figure 2 shows a schematic diagram of a speaker system for a PSZ earphone. (a) is a perspective view of the speaker system 2, (b) is a side view, and (c) is a diagram of the speaker system 2 placed on the ear (right ear). Reference numeral 201 denotes a driver unit, and 202 denotes a diaphragm. An induced magnetic field is generated when a signal current flows through a coil (not shown), which interacts with the magnetic field of a magnet (not shown) to vibrate the diaphragm. Sound waves are emitted from the diaphragm 203 in both directions D1 (the front of the driver unit) and D2 (the rear of the driver unit). The sound waves in the D1 direction and the D2 direction are in opposite phase to each other. Here, sound in the D1 direction is called positive-phase sound, and sound in the D2 direction is 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.

[0004] Without opening 204, the sound waves emitted from opening 203 would propagate to spaces other than the external ear canal, resulting in sound leakage to the surroundings. By superimposing a sound wave of the same amplitude but in the opposite phase on the original sound wave, the original sound wave can be canceled or reduced. Therefore, when sound of the opposite phase is emitted from opening 204, it interferes with sound of the positive phase that propagates from opening 203 in directions other than the direction of the external ear canal, and the two waves cancel each other out near speaker system 2. As a result, sound of the positive phase reaches the external ear canal, but the speaker sound is canceled or suppressed due to interference near speaker system 2, realizing earphones that do not leak sound to the surroundings.

[0005] Japanese Patent Application Laid-Open No. 2023-182166

[0006] Using PSZ earphones (speaker system 2 described above) in the speaker system of the VR glasses shown in Figure 1 is expected to prevent audio content from leaking to the surroundings. Effectively suppressing sound leakage requires careful design of 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 housing, position of openings) of a PSZ earphone-type speaker system suitable for mounting on eyeglass temples is unknown.

[0007] After extensive research, the inventors have discovered the structure of a speaker system (PSZ earphone type) that is suitable for mounting on eyeglass temples. This speaker system includes a driver unit and a housing. The driver unit is positioned approximately parallel to the eyeglass temples, and the interior 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. In the first space, a first sound hole is located on the line connecting the driver unit and the external ear canal, and in the second space, a second sound hole is located close to the first sound hole.

[0008] The disclosed technology provides a speaker system for eyeglass temples that effectively suppresses sound leakage to the surroundings.

[0009] 12A and 12B are diagrams showing an example of VR glasses; a schematic diagram showing a speaker system of PSZ earphones; a diagram explaining a test method for determining the magnitude of sound leakage; a side view and a perspective view of a square speaker system; a side view, a top view, and a bottom view of a square speaker system; a diagram showing an example of an out-of-phase sound hole pattern used in measurement; a diagram showing the frequency dependence of the sound pressure difference value in the 0° direction measured using the sound hole pattern shown in FIG. 6; a diagram showing the frequency dependence of the sound pressure difference value in the 90° direction measured using the sound hole pattern shown in FIG. 6; a diagram showing the directional dependence of the sound pressure difference value by comparing the best pattern with a sealed pattern; a perspective view of the circular speaker system according to the second embodiment worn on the head, and the circular speaker system; a diagram showing the arrangement of out-of-phase sound holes prototyped to find a suitable pattern for the out-of-phase sound holes; a diagram explaining why pattern d in FIG. 10 shows the best results; a diagram showing the arrangement of out-of-phase sound holes prototyped to determine the position of an eccentric out-of-phase sound hole; an overall view explaining why pattern e in FIG. 12 shows the best results. 13A and 13B are enlarged views for explaining that pattern e of Fig. 12 shows the best results. A state in which a speaker system with a sound conduit according to a third embodiment is worn on the head, and an exploded perspective view and side view of the speaker system with a sound conduit. A diagram showing examples of changes in the length, angle, and opening position of the anti-phase sound hole of the sound conduit. A diagram for explaining the results of measurements on three types of speaker systems with a sound conduit, and pattern e of Fig. 13 of the second embodiment. A diagram for explaining the relationship between the cross-sectional area of ​​the sound conduit and low-frequency boost.

[0010] The following describes in detail embodiments of the disclosed technology. Components having the same functions are given the same numbers, and duplicate explanations 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 reproduced. The degree of sound leakage suppression was measured, and a suitable structure was found.

[0011] [Test Method] First, using Figure 3, we will explain the test method for determining the level of sound leakage. Figure 3 shows the case where the right ear of a dummy head was used. A test speaker system 302 was placed near the ear of dummy head 301 (where the speaker system would be located when wearing VR glasses, etc.). An ear-positioned microphone 303 was placed in the external ear canal of dummy head 301. Leakage sound was measured by arranging leakage sound microphones 304 concentrically on a plane at the same height as the ear. The leakage sound microphones 304 were placed 150 mm from the center of the driver unit diaphragm. Eighteen microphones were placed at 15° increments from -45° to 210°, with the front as viewed from the dummy head as the 0° direction. The sound pressure difference value = [sound pressure measured by the leakage sound microphone] - [sound pressure measured by the ear-positioned microphone] was recorded. In other words, the smaller the [sound pressure difference value], the better the sound leakage was suppressed.

[0012] This concludes the explanation of the test method.

[0013] [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."

[0014] First, the above-mentioned [Test Method] was carried out by simulation. Fig. 4(a) is a side (top) view of the square speaker system as 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). Fig. 4(a) shows how the volume of the reverse phase space 402 is changed.

[0015] 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.

[0016] FIG. 5( a) is a side view of the square speaker system viewed from the temporal region 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 from 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. 5( b) is a side (bottom) view of the square speaker system viewed from the jaw side of a dummy head, showing the anti-phase sound holes 501 provided on the bottom surface of the housing. FIG. 5( c) is a top view of the square speaker system, showing the anti-phase sound holes 501 provided on the top surface of the housing.

[0017] We conducted acoustic simulations of approximately 20 patterns by changing the combination of "anti-phase space volume," "number of positive phase sound holes," and "pattern of anti-phase sound holes," and obtained the following results: (1) It is best to reduce the volume of the anti-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 best results are achieved when the anti-phase sound hole pattern has openings only on the sides, not on the top or bottom, and when the openings are located closer to the top of the head and closest to the ears.

[0018] Based on these results, various speaker systems were prototyped and sound pressure differential values ​​were measured using a dummy head. Figure 6 shows an example of the out-of-phase sound hole pattern of the speaker system used in the measurements, while (d) shows a pattern without out-of-phase sound holes (sealed pattern). Figures 7A and 7B show the frequency dependence of the sound pressure differential values ​​in the 0° and 90° directions for patterns a, b, c, and d. Pattern b was found to have the greatest sound leakage suppression effect. Figure 8 shows the polar patterns (directional dependence of sound pressure differential values) for the best pattern b and sealed pattern d. Each polar pattern represents the measurement results when a square speaker system was used to play sounds at 100.26 Hz, 199.87 Hz, 399.47 Hz, 800.13 Hz, 1000 Hz, and 2000 Hz. 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.

[0019] The above is the description of the first embodiment.

[0020] 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."

[0021] Fig. 9(a) shows a state in which eyeglass temples equipped with a circular speaker system 90 according to the second embodiment are attached to a dummy head 301. Fig. 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.

[0022] In the second embodiment, first, a suitable pattern for the anti-phase sound hole was examined. Fig. 10(a) shows a small hole (24.6 mm) in the center of the side surface of the anti-phase space 902 that is perpendicular to the temporal region. 2 Similarly, (b) shows a hole (49 mm) in the center of the same side. 2 ) and (c) a large hole (75.4 mm 2 ), and (d) a small hole (24.6 mm) near the front of the same side. 2 ), and (e) has a four-part hole (6.6 mm) on the same side. 2 ×4) are arranged as shown.

[0023] 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 indicates the possibility of controlling the cancellation frequency by adjusting the distance between the positive and negative phase sound holes and the resonance point.

[0024] Therefore, based on the pattern in Figure 11(d), the position of the anti-phase sound holes was changed and sound pressure difference values ​​were 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 sound pressure difference values ​​were measured. Specifically, for example, in (a) the sound holes were arranged in the front direction of the dummy head, in (c) the direction of the top of the dummy head, and in (b) the sound holes were arranged eccentrically in a 45° diagonal direction between (a) and (c).

[0025] 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 shows 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.

[0026] The above is the description of the second embodiment.

[0027] [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.

[0028] 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. FIG. 14( c) is a cross-sectional view. A circular driver unit 1407 is built into the speaker system with a sound conduit 140, and forms a positive phase space 1401 and a negative phase space 1402. A positive phase conduit 1405 expands the positive phase space 1401 and is provided with a positive phase sound hole 1403 on the side opposite to where the driver unit 1407 is located. A negative phase conduit 1406 expands the negative phase space 1402 and is provided with a negative phase sound hole 1404 on the side opposite to where the driver unit 1407 is located.

[0029] Various types of speakers with sound guide tubes were prototyped using the angle and length of the sound guide tube and the position of the anti-phase sound hole as parameters, and sound difference values ​​were measured. Note that the "sound guide tube 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. Figure 15(a) shows an example of a prototype where the length of the sound guide tube was changed. Figure 15(b) shows an example of a prototype where the angle of the sound guide tube was changed. Figure 15(c) shows an example of a prototype where the positive phase and negative phase conduits are of different lengths. Figure 15(d) shows an example of a prototype where the opening position of the negative phase sound hole was changed.

[0030] After measuring the sound pressure difference values ​​for various prototype speaker systems, the best results were obtained with the following structure. (1) The sound conduit extends from the driver unit toward the external ear canal at an angle (approximately 30°). (2) The length of the negative-phase conduit is longer than the positive-phase conduit. In tests, favorable results were obtained with a prototype with a positive-phase conduit of 20 mm and a negative-phase conduit of 30 mm. (3) The negative-phase sound hole is opened perpendicular to the line connecting the external ear canal and the driver unit. However, while requirement (3) above gave the best results, a high sound leakage suppression effect was also confirmed with a structure that met requirements (1) and (2) and had the negative-phase sound hole opened parallel to the line connecting the external ear canal and the driver unit.

[0031] Figure 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 and negative sound holes facing the same direction. Graph B shows a prototype with a conduit angle of 30°, a positive and negative sound holes facing 20 mm, and a negative-phase conduit length of 30 mm, with the negative sound holes facing perpendicular to the positive sound holes. Graph C shows a prototype with a conduit angle of 30°, a positive and negative sound holes facing 30 mm, and a negative-phase conduit length of 30 mm, with the positive and negative sound holes facing the same direction. For comparison, Graph D shows the results of measurements taken for pattern e in Figure 13 of the circular speaker system of the second embodiment. Graph B provides the best results, achieving a larger sensitivity difference overall than Graph D. Sound leakage is significantly suppressed, particularly at frequencies between 3 kHz and 10 kHz.

[0032] Furthermore, it was discovered that in a speaker system with a sound conduit, changing the opening area of ​​the conduit makes it possible to boost the low frequencies as a secondary acoustic effect. Figure 17 shows the measurement results. Graphs E, F, and G show the frequency dependence of the sound pressure measured with an ear-positioned microphone when the cross section of the sound conduit is 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. Figure 17 shows that when the cross section is small, the acoustic mass increases, and the lowest resonance frequency (so-called f ０ ) is seen to be on a downward trend.

[0033] The above is the description of the third embodiment.

[0034] [Additional Information] In the third embodiment, a circular driver unit was used, but the structure of the sound conduit is important in a speaker system with a sound conduit, so the driver unit may also be square. Also, in the third embodiment, it was stated that favorable results were obtained with a prototype in which the positive phase conduit was 20 mm long and the negative phase conduit was 30 mm long, but the conduit lengths can be changed to suit the design characteristics of the device.

[0035] 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

1. A speaker system to be placed on the temples of eyeglasses worn on the human head, comprising a driver unit and a housing, wherein the driver unit is placed approximately parallel to the temples, 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 auditory canal, and the second space has a second sound hole in a position close to the first sound hole.

2. A speaker system as claimed in claim 1, wherein the driver unit is rectangular, and the second sound hole is located close to the first sound hole, and opens in a direction perpendicular to the driver unit, close to the direction that it will hit the top of the head.

3. A speaker system as claimed in claim 2, characterized in that the volume of the second space is smaller than the volume of the first space, and the first space is substantially perpendicular to the direction in which the temples extend and also has sound holes in the direction in which they contact the chin.

4. A speaker system as claimed in claim 1, wherein the driver unit is circular, and the second sound hole is opened in a direction perpendicular to the driver unit, at a position close to the first sound hole.

5. A speaker system as claimed in claim 1, wherein the first space comprises a first duct that extends along a line (first direction) connecting the driver unit and the external ear canal, and the second space comprises a second duct that extends along the first duct, and the second duct is longer than the first duct.

6. A speaker system as set forth in claim 5, characterized in that the second sound hole is opened in the first direction at the end of the second duct that is closer to the external ear canal.

7. A speaker system as claimed in claim 5, characterized in that the second sound hole is opened in a direction perpendicular to the first direction at the end of the second duct that is closer to the external ear canal.

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