The present application claims priority from Japanese Patent Application No. 2013-217237, which was filed on Oct. 18, 2013, the disclosure of which is herein incorporated by reference in its entirety.
1. Technical Field
The present invention relates to a technique for protecting a speaker unit of a speaker and improving an appearance thereof while adjusting sound quality.
2. Description of the Related Art
In order to protect speaker units or drivers and improve appearances of speakers, conventional speakers in most cases are provided with speaker nets for covering sound emitting surfaces of the respective speaker units. For example, in the case of a speaker in which a single speaker unit is stored in a cabinet having a rectangular parallelepiped shape, the speaker is provided with a speaker net including: a rectangular frame formed along outer edges of a cabinet so as to surrounding a sound emitting surface of the speaker unit; and a sheet member (formed of metal mesh, saran net, or cloth, for example) pasted to an opening portion of the frame so as to cover the entire sound emitting surface. The construction in which such a speaker net is mounted on the speaker avoids direct contact of user's finger with the speaker unit, protecting the speaker unit. Also, suitable material, texture, and coloring of the sheet member improve an appearance of the speaker. Furthermore, the speaker net hides a large speaker unit, e.g., a woofer such that the speaker unit does not directly meet the eyes of the user, resulting in reduced degree of intimidation against the user.
While the speaker net thus plays an important role in, e.g., protecting a speaker unit and improving an appearance of the speaker, the speaker net mounted on the speaker may disadvantageously lower quality of sound traveling to a listener. Specifically, in the state in which the speaker net is mounted, sound pressure in a portion of a high frequency range greatly lowers, and sound in a low frequency range becomes less clear when compared with a state in which the speaker net is not mounted. In order to improve sound quality, some listeners use the speaker in the state in which the speaker net is removed. However, the removal of the speaker net is not preferable because of insufficient protection of the speaker unit.
This invention has been developed to provide a technique capable of both protecting a speaker unit of a speaker and avoiding deterioration of sound quality of reproduced sound.
The present invention provides a speaker including: one or more speaker units; a cabinet accommodating the one or more speaker units; and a speaker net mounted on one of the cabinet and at least one of the one or more speaker units so as to cover a sound emitting surface of each of the at least one of the one or more speaker units. The speaker net includes: a frame surrounding the sound emitting surface of each of the at least one of the one or more speaker units; and a sheet member stuck to the frame to cover the sound emitting surface of each of the at least one of the one or more speaker units. The frame is formed with at least one through hole establishing communication between (i) a space between the frame and the cabinet and (ii) a space outside the speaker.
The present invention also provides a speaker net to be mounted on one of a cabinet accommodating one or more speaker units and at least one of the one or more speaker units to cover a sound emitting surface of each of the at least one of the one or more speaker units. The speaker net includes: a frame surrounding the sound emitting surface of each of the at least one of the one or more speaker units; and a sheet member stuck to the frame to cover the sound emitting surface of each of the at least one of the one or more speaker units. The frame is formed with at least one through hole establishing communication between (i) a space between the frame and the cabinet and (ii) a space outside the speaker.
Experiment and consideration of the inventors of the present invention have shown that, in a conventional speaker including a speaker net, a gap formed between a frame of the speaker net and a surface of the cabinet (i.e., a space between the frame and the cabinet) deteriorates sound quality. In the conventional speaker, as will be explained later in detail, acoustic impedance greatly changes near an opening portion of the gap which is formed at a side face of the speaker and which opens to an outside space. Thus, reflection of sound radiated from speaker units occurs at the open end. This reflected sound encounters and overlaps sound directly transmitted from the speaker units, whereby distribution of sound pressure with nodes and antinodes as in the acoustic mode occurs in front of the speaker, which deteriorates sound quality.
In a speaker of the present invention, a space corresponding to the gap communicates with a space outside the speaker (hereinafter may be referred to as “outside space”) by at least one through hole formed in the frame and is united with the outside space. Thus, the acoustic impedance does not greatly change near the opening portion formed at the side face of the speaker, preventing the reflection of sound at the open end. Consequently, the distribution of sound pressure as in the acoustic mode does not occur in front of the speaker, preventing the deterioration of sound quality. Also, the speaker net according to the present invention of course protects the speaker units. According to the present invention, it is possible to protect the speaker units of the speaker and avoid the deterioration of sound quality of reproduced sound.
It is noted that Patent Document 1 (Japanese Patent Application Publication No. 3-292097) includes a description suggesting that a gap formed between a frame of a speaker net (a speaker grille in Patent Document 1) and a surface of a cabinet deteriorates sound quality. However, Patent Document 1 does not identify how the sound quality is deteriorated, and the speaker grille disclosed in Patent Document 1 does not have the construction for avoiding the above-described sudden change of acoustic impedance. That is, the invention disclosed in Patent Document 1 differs from the present invention.
Hereinafter, there will be described one embodiment of the present invention by reference to the drawings.
A speaker net of a speaker is constituted by a frame and a sheet member. Here, the problem is that it is not adequately clarified which causes the deterioration of sound quality due to the speaker net among the frame, the sheet member, and interaction of the frame and the sheet member and how the deterioration is caused. To clarify these, the inventors of the present invention have conducted the following experiment.
The inventors of the present invention have measured frequency characteristics or response in a case (A) where the speaker from which the speaker net is removed is placed in an anechoic chamber and controlled to emit sound, in a case (B) where the speaker including the cabinet on which only the frame is mounted (i.e., on which the speaker net having no sheet member is mounted) is placed in the anechoic chamber and controlled to emit sound, and in a case (C) where the speaker on which the speaker net is mounted is placed in the anechoic chamber and controlled to emit sound. In each of the cases (A)-(C), a microphone is placed at a position spaced apart from a sound emitting surface of the speaker by a distance of 1.5 m in a direction of a directional axis of the speaker and picks up sound reproduced by the speaker to measure the frequency characteristics.
As apparent when comparing the graph GB01 and the graph GC01 with each other, the presence or absence of the sheet member little affects the frequency response. In contrast, peaks and dips not appearing in the graph GA01 appear in the graph GB01 and the graph GC01 at a frequency range near 7 kHz.
The inventors of the present invention then have measured directional characteristics by causing the microphone to pick up sound having a frequency of 7 kHz while sequentially changing the location of the microphone in the clockwise direction from a direction of the directional axis of the speaker units which is defined as an angle of 0°.
The inventors of the present invention have then considered how the frame deteriorates the sound quality.
In the construction in which the speaker net is mounted on the speaker, the sound waves radiated from the speaker units 14 enter into a space formed between a surface of a cabinet 12 of the speaker and a surface of a frame 16 which is opposite the surface of the cabinet 12 (i.e., a gap having the width ranged from several to a dozen or so mm between the surface of the cabinet and the frame). It is noted that this space is indicated by “GAP” in
Since the reflected sound is caused by the reflection of sound at the open end, the phase of the reflected sound is displaced by an amount corresponding to a half-wavelength with respect to the phase of the directly transmitted sound. This makes it possible to consider that distribution of sound pressure with nodes and antinodes as in the acoustic mode occurs in the space in front of the speaker (see
There will be next explained a speaker according to one embodiment of the present invention with reference to drawings.
In the present embodiment, the portion of the frame 20 which surrounds the sound emitting surface of the tweeter TW has the through holes in the form of the slits 20S for establishing the communication between (a) the space defined between the cabinet and the frame 20 and (b) the outside space existing in front of the speaker. Thus, the space defined between the cabinet and the frame 20 communicates via the slits 20S with the outside space existing in front of the speaker and is thereby united with the outside space (see
In addition or instead of the portion of the frame 20 which surrounds the sound emitting surface of the tweeter TW, a plurality of through holes 20S may be formed in a portion of the frame 20 which differs from the portion of the frame 20 which surrounds the sound emitting surface of the tweeter TW.
With the above-described construction in which the speaker net 18 includes the frame 20 in the present embodiment, it is possible to avoid deterioration of sound quality of reproduced sound. That is, in the present embodiment, it is possible to both protect the speaker units and avoid deterioration of sound quality.
While the embodiment of the present invention has been described above, it is to be understood that the invention is not limited to the details of the illustrated embodiment, but may be embodied with various changes and modifications, which may occur to those skilled in the art, without departing from the spirit and scope of the invention.
While the frame having the characteristics of the above-described embodiment is mounted on the cabinet for storing the speaker units in the above-described embodiment, the frame may be mounted on at least one of the speaker units. While the present invention is applied to the speaker in which the speaker units of various types are stored in the cabinet in a state in which the sound emitting surfaces of the respective speaker units are arranged in a line in the above-described embodiment, the present invention may be applied to a speaker in which a plurality of speaker units having the same frequency range of reproduced sound are stored in the cabinet, for example, the present invention may be applied to a speaker array. In this construction, since the speaker units have the same frequency range of reproduced sound, the entire frame is formed, for example, to have through holes for establishing communication between (a) a space between the cabinet and the frame and (b) the outside space.
The present invention may be applied to a speaker in which only one speaker unit is stored in the cabinet. Specifically, one example of such a speaker includes: a speaker unit; a cabinet accommodating the speaker unit; and a speaker net mounted on the cabinet or the speaker unit so as to cover a sound emitting surface of the speaker unit, wherein the speaker net includes: a frame surrounding the sound emitting surface of the speaker unit; and a sheet member stuck to the frame so as to cover the sound emitting surface of the speaker unit, and wherein the frame is formed with at least one through hole for establishing communication between (i) a space between the cabinet and the frame and (ii) an outside space.
A speaker net may be offered alone which includes: a frame surrounding a sound emitting surface of at least one speaker unit; and a sheet member stuck to the frame so as to cover the sound emitting surface of the at least one speaker unit, wherein the frame is formed with at least one through hole for establishing communication between (i) a space between a cabinet and the frame and (ii) an outside space. For example, various types of speaker nets including sheet members having respective different materials, textures, or colorings are placed on the market as speaker nets mountable on a particular speaker. This situation allows users of the speaker to choose and use a speaker net that matches (i) an atmosphere of a room in which the speaker is placed and (ii) other pieces of furniture in the room.
Number | Date | Country | Kind |
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2013-217237 | Oct 2013 | JP | national |