Sound Reproduction System

Abstract

To provide a sound reproduction system that is easy to attach and makes possible better sound quality, sound field, and multi-functionality.SOLUTION: Rings 1a and 1b, which are worn on the head like a crown, hold speakers 3L, 3R from two points on the circumference so that they do not come in contact with the ears, and the head alone supports the entire structure, including the speakers and a holding mechanism. The left speaker 3L is coupled with a coupling part 5L via a pillar 4L. The coupling part 5L can be fixed at any angle by tightening it with a screw. The right speaker 3R has a similar structure. Thereby, the location relationship of the ears and the speakers is fixed regardless of the movement of the neck.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sound reproduction system that does not block the ears, such as a shoulder speaker. [Background technology]

[0002] In today's world, the dramatic advances in liquid crystal display technology have made it possible to get large screens that were previously unthinkable at affordable prices for what are known as home theaters. As a result, large, high-definition images have already been realized. On the other hand, while it is technically and economically possible to produce sound at the same volume as in a movie theater, there is another reason why home theaters are still not possible in ordinary homes that do not have soundproof rooms, namely because of the nuisance (noise) caused by sound diffusing to the surroundings.

[0003] So, various shoulder-mounted speakers that allow a single person to experience loud sound are available on the market. The shoulder-mounted type is the most common, but due to weight restrictions, even if the sound is loud, the reproduction of low frequencies is insufficient, so the incredible sense of realism like that of a movie theater cannot be realized. In particular, the low frequencies of 50Hz and 40Hz that are reproduced in movie theaters cannot be reproduced by shoulder-mounted speakers that use small speakers, so the current situation is that instead of low frequencies, the feeling of low frequencies is artificially compensated for by other means such as vibration.

[0004] In addition, the relative position between the ears and the speakers placed on the shoulders changes as the neck moves, causing problems with the left-right volume difference and sound localization. This makes it impossible to reproduce an accurate sound field. Furthermore, adding features such as noise canceling used in inner-type earphones is quite difficult with the shape of typical shoulder-mounted speakers, as the position of the ears and the speakers changes.

[0005] Shoulder-mounted speakers are not only great for watching movies, concerts, and sports in a home theater, but they can also be used to practice electronic instruments, allowing you to listen to music at a loud volume without disturbing those around you. However, because the speakers are placed on the shoulder, they cannot be used with electronic instruments such as cellos and violins. They are also not ideal for electronic instruments such as drums, which are mainly bass-heavy, as they lack bass.

[0006] Additionally, there are already speakers attached to helmets and HMDs (head mounted displays) that do not have speakers on the shoulders. Although they serve the same purpose in terms of listening to sound, helmet speakers do not use two speakers, one on each side, and do not require low-frequency reproduction, as the frequency band is narrowed to make them easier to hear. This is completely different from the improvements in sound quality, localization, and noise cancellation that are intended by this invention.

[0007] As for the speakers for the HMD, the HMD is worn using the head and nose to mainly hold the heavy display, and the speakers are held in the same way, with the speakers and ears in close contact and the face (nose and auricles) and head are used together to hold the heavy display and prevent it from shifting with body movements. This is basically the same structure as regular large headphones, and they press against the ears, so it cannot be said that they are comfortable to wear. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2020-136964 [Patent Document 2] Patent Publication 2018-119241 [Patent Document 3] Patent Publication No. 2018-129054 Summary of the Invention [Problem to be solved by the invention]

[0009] The above-mentioned Patent Document 1 shows a typical shoulder-mounted speaker system, but the speakers used are small, about 3 cm in diameter, and the distance to the auricle is about 14 cm, so there is an issue of insufficient bass reproduction, and various measures are required to compensate for this. Also, since the positional relationship between the ears and the speakers is not fixed, there are issues with the sound localization changing when the neck moves, and with the occurrence of a difference in volume between the left and right.

[0010] In the above Patent Document 2, a sturdy helmet that prioritizes safety is used, but it is heavy and has poor ventilation, which makes it uncomfortable to wear. In addition, a structure with one speaker on either the left or right side is shown, but the purpose is clearly to give instructions or communicate with others, and the sound quality of the speaker is about the same as that of a mobile phone with no bass.

[0011] As for Patent Document 3, the application is similar and sound quality and positioning are important, but the speaker is held not only on the head but also on the face (nose and ears). Since the display of an HMD is large and heavy, it is difficult to hold it on the head without using the face. Also, if the nose is not tightly attached, external light will affect the display, making it difficult to hold it on the head alone. This results in a fairly complicated structure, a poor fit, and high costs. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides an audio reproduction system comprising a ring that contacts the head and surrounds the head in an approximately circular shape, speakers positioned near each of the left and right ears, and a holding mechanism that holds the speakers outside the ring and in a position not in contact with the ears, wherein the entire system including the speakers and the holding mechanism is supported only by the ring on the head. Effect of the Invention

[0013] According to the present invention, by using a ring and placing the speaker close to the ear but not in contact with it, the structure is simple and comfortable to wear, and the deep bass sound of the subwoofer, which is the most annoying sound in a home theater, can be heard sufficiently by the listener, but since there is no diffusion to the surroundings, even if you play the sound at a loud volume like in a movie theater at home, it will not bother those around you. Of course, even if you move your neck, the ear and the speaker move together, so there is no deviation in the sense of sound field positioning or difference in volume between the left and right.

[0014] In addition, according to the present invention, the device can be made lighter due to the minimal holding mechanism, and the speaker is placed without contact with the ear, so the wearing comfort is much better than that of helmet-type or HMD-type devices. Therefore, not only can you watch movies, concerts, and sports, but you can also practice instruments at high volume, including low-pitched sounds such as bass drums of electronic instruments. In addition, you can play instruments such as violins and cellos, which you cannot do with general shoulder speakers, because there is nothing on your shoulder. Sound pressure equivalent to that heard 2 meters away from a floor speaker can be provided with only about 1 / 40,000 of the power consumption. In the case of general shoulder speakers, the power consumption is about 1 / 200, so the difference is 200 times. With products that use batteries, the continuous playback time can be greatly differentiated. If the power consumption of audio products, which are used by billions of units around the world, can be reduced, it will also be effective in combating global warming. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a diagram for explaining the arrangement of a size-adjustable ring and a speaker in an embodiment of the sound reproduction system according to the present invention. [Diagram 2] Figure 1 is a front view showing the relative positions of the ring, speaker, and ears. [Diagram 3] 1 is a diagram for explaining the arrangement of a size-adjustable ring, a U-shaped band, and a speaker in an embodiment of the sound reproduction system according to the present invention. FIG. [Figure 4] Figure 3 is a top view showing the ring, U-shaped band, and structure that can be adjusted in length to fit the shape of the head. [Diagram 5]FIG. 4 is a front view of a listener using the device shown in FIG. [Figure 6] This is a view from the left side of the listener in Figure 3 when being used. [Figure 7] FIG. 1 is a diagram for explaining the arrangement of microphones to be used when adding a noise canceling function or an echo canceling function required for a hands-free function in an embodiment of the sound reproducing system according to the present invention. [Figure 8] 1 is a cross-sectional view of a speaker used in the present invention and shows the positional relationship of an associated microphone. [Figure 9] FIG. 1 is a diagram for explaining a general circuit system configuration when a noise cancellation function is added to an embodiment of the sound reproducing system according to the present invention. [Figure 10] FIG. 1 is a diagram for explaining a general circuit system configuration of an echo cancellation function required when a hands-free function is added to an embodiment of the sound reproduction system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment of the sound reproduction system according to the present invention will be described below. In each figure, R indicates the right side of the listener, and L indicates the left side.

[0017] 1 and 2 are diagrams for explaining the relative positions and structures of a ring and left and right speakers in an embodiment of an audio reproduction system according to the present invention.

[0018] As shown in Fig. 1, in this embodiment, the ring is divided into two parts, 1a at the front and 1b at the rear, so that the circumferential length can be adjusted to fit the shape of the listener's head. Both ends 1aR and 1bR, and 1aL and 1bL are made of a material such as Velcro (registered trademark), and the size of the ring can be adjusted to fit the shape of the listener's head.

[0019] Figure 2 shows the front view of the ring when worn by a listener on the head. As can be seen in the figure, the left and right ends of the ring 1a are structured so that speaker 3L can be held close to the left ear and speaker 3R can be held close to the right ear without touching them. The left speaker is connected to 5L via a support 4L. The connection part 5L is structured to firmly fix the connection in relation to the position of the ear. For example, 5L can be fixed at any angle by tightening a screw. The right speaker has a similar structure. If the connection part 5L is structured so that the left and right speakers can be moved significantly toward the head when not in use, and if the support 4L is structured to be rotatable or foldable, more compact storage will be possible.

[0020] In this embodiment, the ring is made up of two parts, but it may be made up of one part, or it may be made up of three or more parts to allow for greater freedom in design and a better fit (breathability).

[0021] Figure 3 is a diagram in which U-shaped bands 2L and 2R have been added to Figure 1. Depending on the shape of the listener's head, the addition of a U-shaped band may improve the fit. The U-shaped band is also made of two parts, and when the U-shaped band is attached, joints 6L and 6R are provided at both ends of the ring 1a, allowing the U-shaped band to move freely, but the U-shaped band can also be removed from the joints when it is not needed. The ends of the U-shaped band also have 2Lb and 2Rb, made of a material such as Velcro (registered trademark) like the ring, allowing the length of the band to be adjusted.

[0022] Fig. 4 is a top view of Fig. 3, showing the relationship between each part. Fig. 5 is a front view of Fig. 3 with the addition of a U-shaped band, worn on the head of a listener. Fig. 6 is a left side view of Fig. 5. The ring does not necessarily have to be horizontal to the floor, and the angle θ at which the ring and U-shaped band intersect can be freely changed according to the listener's preference. The positional relationship between the speaker and the ear does not change even if a U-shaped band is added, so the embodiment will be explained based on the configuration of the ring and speaker in Fig. 1.

[0023] Also, the positional relationship between the ears and the speaker is always the same and very close, which is a big difference from shoulder-mounted speakers. In a typical shoulder-mounted speaker, the distance between the ears and the speaker is about 14 cm. If you compare listening to the same volume as listening to a TV speaker 2 m away, if the distance is 14 / 200, the power is inversely proportional to the square of the distance, so it is 196 / 40000, or about 1 / 200 of the power. In this invention, the distance is considered to be 1 cm, and the distance is further 1 / 14, so the power is saved by about 1 / 200. In other words, it requires only a small amount of power consumption to listen to the same volume. If you can listen to the same volume with less power, the amplitude of the speaker's diaphragm becomes smaller, and if the amplitude is small, the depth of the speaker becomes shorter, the magnet that drives the speaker's diaphragm becomes smaller, the weight becomes smaller, the cost decreases, and the distortion decreases, and yet the performance improves, creating a virtuous cycle.

[0024] FIG. 7 shows four microphones attached near the left speaker. This is because microphones are necessary to pick up external sounds when adding a noise cancellation function or a hands-free calling function to the present invention. For example, four microphones 8 to 11 are placed near the speaker. As shown in FIG. 8, speaker 3L is a typical dynamic speaker with a cone-shaped diaphragm 14 attached to a frame via an edge 7. A magnetic circuit that drives diaphragm 14 is housed in cylindrical part 12L at the rear of the frame. There are holes 15, 16, 17, and 18 on the back of the speaker frame, and diaphragm 14 is driven by the magnetic circuit to perform piston motion, radiating sound into the air.

[0025] A positive phase sound is generated in front of the diaphragm 14, and an opposite phase sound is generated behind it, and these are radiated into space through the holes. These holes are holes that allow the sound coming from behind the diaphragm to pass and be added in space with the sound coming from in front of the diaphragm, and the result of the addition creates a null area (silent area) on the circumference of the speaker. As a result, a silent area (dashed line 13) is created on the outermost circumference of the speaker 12L where the positive phase and opposite phase are added and cancel each other out. The dashed line indicated by 13 indicates the null area (silent area) where the sound coming from the diaphragm disappears. Normally, to prevent this situation from occurring, speakers are placed in a box to confine the opposite phase sound, but the present invention does not use a box and instead actively utilizes the silent phenomenon.

[0026] That is, in the area where the sounds coming from the front and rear of the speaker diaphragm cancel each other out, the sound coming from the speaker itself does not enter the microphone, so there is an advantage that the processing when adding a signal of the opposite phase to the input signal when canceling external noise is simplified. The microphone is installed in a place where the sum of the sounds coming from the front and rear of the speaker diaphragm is zero (the area of ​​the dashed line 13). However, since there are influences from the nose, auricle, and shoulders on the face, the area of ​​the dashed line 13 is not necessarily the most effective place for cancellation, and if multiple microphones can be placed, they may be placed in a position slightly outside the ideal silent area and used selectively depending on the situation. Once the microphone position with a good cancellation effect is determined, there is an advantage that the positional relationship between the ear and the speaker is fixed in this invention even if the neck moves, so cancellation control can be performed stably. The same effect can be obtained by providing a mechanism to mechanically move the position of one microphone instead of using four microphones.

[0027] FIG. 9 explains an embodiment of the present invention in which a noise cancellation function using multiple microphones is added. For example, a music source is transmitted from a mobile phone to a receiving unit 28 via an antenna 27 using a wireless communication technology called Bluetooth (registered trademark). Of course, the music source is not limited to wireless, and may be a CD player or a cassette player. In order to pick up noise around the listener, for example, as shown in FIG. 7, four microphones are placed in a silent area or an area corresponding to the entrance of the ear, and one is selected from a microphone changeover switch 19 and supplied to a microphone amplifier 20. The signal amplified by the microphone amplifier 20 is supplied to a bandpass filter 21. The bandpass filter 21 is for separating the frequency components of the noise to be canceled, and mainly extracts components of 80 Hz to 1 KHz. The mixer 22 is composed of level adjusters 23 and 24 that adjust the signal levels of the two inputs, and an adder 25. The output signal of the bandpass filter 21 is phase-inverted and supplied to the mixer 22, and added to the adder 25 via the level adjuster 23. The output signal of the mixer 22 is supplied to the speaker 3L via an amplifier 26. The amplifier 26 is a so-called integrated amplifier that combines the functions of a preamplifier, such as a volume and an equalizer, with the function of a power amplifier that amplifies the signal level.

[0028] The digitally transmitted music source is decoded in the transmitting / receiving section and output as an analog signal from Line Out 30. If one wishes to listen to a desired music signal in addition to noise cancellation, the audio signal is passed through level adjuster 24 and adder 25 in mixer 22, amplified by amplifier 26, and sent to speaker 3L. As described above, since out-of-phase sound waves are emitted from speaker 3L, the noise contained in the sound waves from the speaker and the noise at the selected microphone position cancel each other out, making it possible to cancel noise. On the other hand, music signals and the like sent from a mobile phone are in-phase and are output directly from the speaker.

[0029] Fig. 10 explains an embodiment of the present invention that adds a hands-free calling function. Many current headphone products have built-in wireless communication transmitters and receivers, and the music source is first stored in the memory of a mobile phone or the like, then transmitted to the headphones using wireless communication, where it is decoded by the receiver in the headphones and output. Therefore, if a call comes in while listening to music, the Line Out 30 of the transmitter and receiver can be switched from the music source to the call from the other party by operating the headphones. At this time, one of the microphones placed near the speaker picks up the voice of the listener who received the call, rather than noise.

[0030] The echo cancellation function required for hands-free operation will be described below. For example, a voice is picked up by a microphone 9 attached near the speaker, amplified by a microphone amplifier 20, sent to Mic IN 29, and sent to the other party's mobile phone via an RF transmission unit. The other party's voice is output from Line Out 30 and output from the left speaker 3L. The other party's voice is picked up by the microphone 9 near the speaker, sent again to the other party, and goes around and around, which is called an echo. To prevent this, echo cancellation is performed using the configuration surrounded by dotted lines in Figure 10. An FIR filter 32 is incorporated to attenuate the sound that becomes an echo, and a commonly known adaptive filter process is performed on the signal coming out of Line Out 30 to detect the difference with the microphone signal, which is monitored by the control unit CTL31 as an error signal Er33 and the coefficient of the FIR filter is controlled so that the signal is attenuated. At this time, in the present invention, the microphone 9 is placed in a silent area where sounds coming from the front and rear of the speaker's diaphragm cancel each other out, so it is difficult to pick up an echo signal from the speaker, which has the advantage of making the processing of the control unit CTL31 lighter.

[0031] As with noise cancellation, the effect of echo cancellation for the hands-free function can be improved by having multiple microphones in the silent area. In addition, for example, microphone 9 is located on the lower part of the face, that is, closest to the lips, and microphones 8, 10, and 11, as well as four microphones on the right side, can be changed to detect the direction from which the sound is coming and to give the microphones directionality. The hands-free function can also function with only one side. The noise cancellation mentioned above can also be digitally processed using an adaptive filter.

[0032] In this way, the present invention allows the creation of products that are lightweight and inexpensive with a simple mechanical structure. Above all, because the ears are not blocked, the sound can be heard in a much more natural way than with headphones, and because there is no pressure around the ears, a much better fit is obtained compared to conventional headphones. In addition, it has the advantage of not only allowing the user to enjoy powerful sound with only a small amount of power, but also not disturbing those around them. With the development of various new electronic musical instruments, beginners can practice at a sufficient volume without having to build a soundproof room or worrying about the repeated sounds of poor performances or the time of practice, which contributes to the improvement of music culture. [Explanation of symbols]

[0033] 1a, 1b: Rings divided into front and back, 1aR, 1aL: Magic Tape (registered trademark) portion of 1a; 1bR, 1bL: Magic Tape (registered trademark) portion of 1b; 2R, 2L: U-shaped band divided into left and right, 2Rb, 2Lb: Velcro (registered trademark) part of U-shaped band, 3R, 3L: Left and right speakers, 4R, 4L: Left and right speaker posts, 5R, 5L: Left and right speaker connection parts, 6R, 6L: Joint of left and right U-shaped bands, 7: Edge 8, 9, 10, 11: Microphones to be installed near the speaker, 12L, 12R: Magnet parts of left and right speakers, 13: The area where the sounds before and after the speaker diaphragm are added together and silence occurs 14: Cone speaker diaphragm 15, 16, 17, 18: Holes on the rear of the speaker frame 19: Microphone switch 20: Microphone amplifier 21: BPF (Band Pass Filter) 22: Mixing section 23, 24: Level adjuster 25: Addition section 26: Amplifier 27: Antenna 28: Transmitter / receiver 29: Microphone input 30: Line output 31: Control circuit section 32: FIR filter 33:Er error signal

Claims

[Claim 1] a ring in contact with the head and generally circumferentially surrounding the head; A speaker disposed near each of the left and right ears; a retaining mechanism for retaining the speaker outside the ring and in a position not in contact with the ear; In a head-mounted sound reproducing system in which the entire system including the speaker and the holding mechanism is supported only by a ring on the head, A head-mounted sound reproducing system characterized in that the speaker is not covered by a box but is held in the exposed state so as not to block the ears but in close proximity to the ears.

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