Video display device

Abstract

In the present invention, for example, a directional speaker is disposed at an appropriate position on the back surface of a video display unit.　This video display device includes: a video display unit having a video display surface and a back surface part that is on the side opposite the video display surface; and a pair of directional speakers provided on the back surface part. The distance between the pair of directional speakers is 850-1050 mm, and the distance from an upper peripheral edge section of the back surface part to the directional speaker is 130 mm or less.

Description

Video display device

[0001] The present disclosure relates to a video display device.

[0002] There is known an acoustic reproduction device in which an opening is provided in a cylindrical sound guide tube and sound is reproduced from the opening. Patent Document 1 listed below describes a technology in which such an acoustic reproduction device is provided on the back of a television set and the sound of the television set is reproduced from the acoustic reproduction device in a direction upward of the television set. This allows the sound image of the sound reproduced from the television set to be localized in the direction upward of the television set (upward localization).

[0003] U.S. Pat. No. 1,105,1103

[0004] However, if the position of the sound reproduction device is not appropriately set, not only will sound not be localized upward, but there is also a risk that the sound image will be localized in a way that makes the user feel uncomfortable. Patent Document 1 leaves room for improvement, for example, with regard to the position of the sound reproduction device.

[0005] An object of the present disclosure is to provide a video display device in which a directional speaker, which is a sound reproduction device, is arranged in an appropriate position.

[0006] The present disclosure relates to an image display device having, for example, an image display unit having an image display surface and a rear surface opposite the image display surface, and a pair of directional speakers provided on the rear surface, wherein the distance between the pair of directional speakers is 850 mm or more and 1050 mm or less, and the distance from the upper peripheral edge of the rear surface to the directional speakers is 130 mm or less.

[0007] 1 is a diagram for explaining an example of a sound reproduction system to which the present disclosure can be applied. FIG. 1 is a diagram for explaining an example configuration of a rear part of a video display device according to an embodiment. FIG. 1 is a diagram referred to when describing problems to be considered in the present disclosure. FIG. 1 is a diagram referred to when describing problems to be considered in the present disclosure. FIG. 1 is a diagram referred to when describing problems to be considered in the present disclosure. FIG. 1 is a diagram for explaining an example configuration of a directional speaker according to an embodiment. FIG. 2 is a diagram for explaining an example operation of a directional speaker according to an embodiment. FIG. 3 is a diagram for explaining the distance between directional speakers according to an embodiment. FIG. 4 is a diagram for explaining a reflected sound image formed when the distance between directional speakers according to an embodiment is too large. FIG. 5 is a diagram for explaining a reflected sound image formed when the distance between directional speakers according to an embodiment is appropriate. FIG. 6 is a diagram for explaining a reflected sound image formed when the distance between directional speakers according to an embodiment is too small. FIG. 7 is a diagram referred to when explaining the vertical position, etc. of a directional speaker according to an embodiment. FIG. 8 is a diagram for explaining a reflected sound image formed when the vertical position of a directional speaker according to an embodiment is appropriate. FIG. 9 is a diagram for explaining a modified example.

[0008] Embodiments of the present disclosure will be described below with reference to the drawings. The description will be made in the following order: <Outline of the present disclosure and problems to be considered in the present disclosure> <One embodiment> <Modification> The embodiments described below are preferred specific examples of the present disclosure, and the contents of the present disclosure are not limited to these embodiments. The dimensions, materials, shapes, relative positions, and directions (up, down, left, right, etc.) of components described in the embodiments are merely illustrative examples, and are not intended to limit the scope of the present disclosure unless otherwise specified. The size and positional relationships of components shown in each drawing may be exaggerated for clarity. Furthermore, to avoid cluttering the illustrations, only some reference symbols may be shown or some parts may be simplified. Furthermore, in the following description, the same names and symbols indicate identical or similar components, and redundant descriptions will be omitted as appropriate.

[0009] <Outline of the present disclosure and problems to be considered in the present disclosure> First, in order to facilitate understanding of the present disclosure, an outline of the present disclosure and problems to be considered in the present disclosure will be described.

[0010] [Sound Reproduction System] FIG. 1 is a diagram illustrating an example of an audio reproduction system (audio reproduction system 1) to which the present disclosure can be applied. The audio reproduction system 1 includes, for example, a video display device 10. Examples of the video display device 10 include a television device that reproduces broadcasts, but it may also be a device that reproduces content transmitted via the Internet, or a device that has both functions. A user U watches and listens to the video and sound reproduced from the video display device 10 in an acoustic space in the audio reproduction system 1. The acoustic space includes a wall RW and a ceiling CE. The video display device 10 is installed in front of the wall RW. For example, the video display device 10 is placed on a stand 20 installed on the floor. Note that the video display device 10 may be hung on the wall RW rather than placed on the stand 20.

[0011] [Image Display Device] Image display device 10 is a device applicable to an embodiment described later. Here, the main components of image display device 10 will be described. Image display device 10 has an image display unit 11. Image display unit 11 generally has a thin, plate-shaped resin housing, with a display provided on a predetermined main surface of the housing. Specifically, image display unit 11 has an image display surface 12, which is one main surface, and a back surface 13, which is the side opposite to image display surface 12. Display 12A is provided on image display surface 12. An organic EL (Electro Luminescence) or LCD (Liquid Crystal Display) can be used as display 12A.

[0012] A directional speaker 30 is provided on the rear surface 13 of the video display unit 11. The directional speaker 30 is a speaker device having directivity in a predetermined direction, specifically, a diagonally upward direction. A sound beam BM propagating in the above-mentioned direction is generated by the sound reproduced from the directional speaker 30. A specific configuration example of the directional speaker 30 will be described later.

[0013] Here, an example of the main configuration of the rear portion 13 will be described with reference to FIG. 2 . As shown in FIG. 2 , the rear portion 13 has a generally rectangular shape overall. The rear portion 13 has, for example, an upper peripheral portion 13A, a lower peripheral portion 13B, a right peripheral portion 13C, and a left peripheral portion 13D. A directional speaker 30 is provided a predetermined distance below the upper peripheral portion 13A of the rear portion 13. The directional speaker 30 includes a pair of directional speakers, directional speaker 30A and directional speaker 30B. The directional speaker 30A is provided on the right side as viewed from the rear portion 13, and the directional speaker 30B is provided on the left side as viewed from the rear portion 13. The directional speaker 30A is located on the left side as viewed from the user U, and therefore reproduces sound corresponding to the L (left) channel. Conversely, the directional speaker 30B is located on the right side as viewed from the user U, and therefore reproduces sound corresponding to the R (right) channel. When there is no need to distinguish between the directional speakers 30A and 30B, they will be referred to as directional speaker 30 as appropriate.

[0014] A pair of woofer units are provided below the directional speaker 30. For example, a woofer unit 40A is provided below the directional speaker 30A, and a woofer unit 40B is provided below the directional speaker 30B. When there is no need to distinguish between the woofer units 40A and 40B, they will be referred to as the woofer unit 40 as appropriate. Low-frequency sounds (e.g., 20 Hz to 600 Hz) are reproduced from the woofer unit 40. Because low-frequency sounds spread more widely than high-frequency sounds, they are propagated to the user U even when reproduced from the rear portion 13.

[0015] A pair of exciters are provided below the woofer unit 40. For example, an exciter 50A is provided below the woofer unit 40A, and an exciter 50B is provided below the woofer unit 40B. When there is no need to distinguish between the exciters 50A and 50B, they will be referred to as exciters 50 as appropriate. The exciter 50 is a device that vibrates the video display unit 11. When the exciter 50 operates, the video display unit 11 vibrates. Sound is generated by the vibration of the video display unit 11, and the generated sound is heard by the user U. The woofer unit 40 and the exciter 50 are not necessary.

[0016] [Operation of Sound Reproduction System] Returning to FIG. 1 , the operation of the sound reproduction system 1 will be described. A sound beam BM is generated by reproducing sound from the directional speaker 30 of the video display device 10. In FIG. 1 and FIG. 4 described later, the propagation direction of the beam BM is indicated by a dotted arrow. The beam BM is reflected by the wall RW facing the rear surface 13 and heads toward the ceiling CE. The beam BM is then reflected by the ceiling CE and heads downward, propagating toward the user U. A reflected sound image RS is generated at a predetermined location on the ceiling CE by the sound beam BM reflected by the wall RW. Specifically, a reflected sound image RS is formed at a predetermined location on the ceiling CE, including two reflected sound images: a reflected sound image RSA formed by the beam BMA from the directional speaker 30A, and a reflected sound image RSB formed by the beam BMB from the directional speaker 30B. The user U can get a sense of the spaciousness of the sound field by perceiving the reflected sound image RS in addition to the sound (direct sound) reproduced from the image display device 10. Furthermore, the reflected sound image RS allows the user U to get a sense of the sound being localized not only in front (the direction of the image display device 10) but also upward.

[0017] [Issues to be Considered in the Present Disclosure] Next, issues to be considered in the present disclosure will be described with reference to FIGS. 3 to 5. FIG. 3A illustrates an example in which the distance (spacing) between the directional speaker 30A and the directional speaker 30B is greater than the appropriate distance. If the spacing between the directional speaker 30A and the directional speaker 30B is too large, as shown in FIG. 3B , the spacing between the sound beam BMA generated by the operation of the directional speaker 30A and the sound beam BMB generated by the operation of the directional speaker 30B becomes wider. As a result, the spacing between the reflected sound image RSA formed by the reflection of the beam BMA on the wall RW and the reflected sound image RSB formed by the reflection of the beam BMB on the wall RW also becomes wider. This causes the sense of localization of the sound image perceived by the user U to be pulled extremely outward, resulting in almost no sense of localization near the center, and a hollow center in which the sense of localization of the sound does not match the sense of localization of the image reproduced on the image display device 10. Furthermore, although the directional speakers 30A and 30B have a certain degree of directivity, there is leakage of sound in directions other than the intended direction of directivity (sound leakage in Figure 3B). If the directional speakers 30A and 30B are placed close to the right peripheral portion 13C or the left peripheral portion 13D, there is a risk that such sound leakage will propagate toward the user U via the edge of the video display unit 11. This raises concerns that the sense of sound image localization near the center will be further stretched. For the above reasons, it is not desirable for the distance between the directional speakers 30A and 30B to be too large. Note that the sound image SIW in Figure 3B represents the sound image generated by low-frequency sounds reproduced from the woofer unit 40 (the same applies to Figure 4B).

[0018] On the other hand, it is also undesirable for the spacing between directional speaker 30A and directional speaker 30B to be too close, as shown in FIG. 4A . The reason for this is that, as shown schematically in FIG. 4B , if the spacing between directional speaker 30A and directional speaker 30B is too close, the proximity of beams BMA and BMB causes them to partially combine, resulting in a sound image resembling a rooster's comb. As a result, a reflected sound image RS with strong sound pressure near the center is formed on the ceiling CE. In other words, the stereo effect perceived by user U in the upward localization is diminished, and the central localization is overemphasized. This may result in a mismatch between the image and sound localization reproduced on the video display device 10. For these reasons, it is also undesirable for the spacing between directional speaker 30A and directional speaker 30B to be too small.

[0019] So far, we have considered the horizontal position of the directional speaker 30, but the vertical position must also be considered. For example, suppose the distance between the directional speaker 30 and the upper peripheral portion 13A is increased and the directional speaker 30 is located below the rear portion 13. If the directional speaker 30 is positioned too low, as shown schematically in FIG. 5 , the beam BM reflected by the wall RW is blocked by the rear portion 13 of the image display device 10 and cannot travel toward the ceiling CE. This may result in a lack of a reflected sound image RS on the ceiling CE, making upward localization impossible. Furthermore, even if a reflected sound image RS is formed on the ceiling CE, the sound pressure will be low, so the direct sound from the image display device 10 will predominate, increasing the risk that the user U will not experience the sense of upward localization provided by the reflected sound image RS.

[0020] For these reasons, it is necessary to arrange the directional speaker 30 at an appropriate position on the rear surface 13 of the image display device 10. Taking this into consideration, the details of the present disclosure will be described with reference to an embodiment.

[0021] <One embodiment> In one embodiment, the above-described sound reproduction system 1 and video display device 10 can be applied. The configuration examples and operations thereof have already been described, so duplicated description will be omitted.

[0022] 6A and 6B are diagrams illustrating an example of the configuration of the directional speaker 30 according to one embodiment. In this embodiment, the directional speakers 30A and 30B have the same components, but there may be differences in configuration between the two.

[0023] FIG. 6A is a plan view of the directional speaker 30, and FIG. 6B is a side view of the directional speaker 30. The directional speaker 30 has a tubular (cylindrical) sound conduit 31. The sound conduit 31 is a hollow tubular member in which an internal space SP1 is formed, and is made of resin or metal. A tip 32 (an example of one end) of the sound conduit 31 is closed. The opposite side to the tip 32 is an open end 33 (an example of the other end). The sound conduit 31 has a shape in which the vicinity of the open end 33 is slightly bent toward the open end 33. The sound conduit 31 also has a substantially flat surface 31A on its upper side (the -Z direction side in FIG. 6A ).

[0024] The directional speaker 30 also includes a speaker unit 34. The speaker unit 34 is a tweeter unit that reproduces high-frequency sounds above a predetermined frequency. High-frequency sounds above a predetermined frequency include, for example, sounds above 5 kHz. A signal that passes through a high-pass filter with a cutoff frequency of 5 kHz in an audio processor (not shown) is provided to the speaker unit 34 and reproduced. The sound reproduced from the directional speaker 30 corresponds to the image displayed on the video display unit 11 and may be synchronized with the image. The sound may be music, a human voice, environmental sounds, or any other sound. Note that the video display device 10 may be configured to reproduce only music, for example, without displaying an image. The directional speaker 30 is also referred to as a beam tweeter because it functions as a tweeter that generates a sound beam (BM).

[0025] Note that a speaker unit that reproduces mid-range sounds or a full-range speaker unit that reproduces sounds over the entire frequency range may be applied as the speaker unit 34. The source to the speaker unit 34 may be supplied via a wired connection such as a cable, or may be supplied wirelessly such as via Bluetooth (registered trademark).

[0026] The speaker unit 34 is attached to the open end 33. For example, the speaker unit 34 is attached to the open end 33 so that the direction of sound emission from the speaker unit 34 is toward the internal space SP1 of the sound conduit 31.

[0027] A plurality of holes (holes 35A, 35B) that communicate with the internal space SP1 are formed in the flat surface 31A of the sound conduit 31. The shapes of the holes 35A, 35B are, for example, substantially circular, but may be other shapes such as rectangular.

[0028] The plurality of holes 35A are arranged in a substantially aligned first row CA along the extension direction of the sound conduit 31 (the X direction in FIG. 6A ). The plurality of holes 35A form a first hole group 36A. The plurality of holes 35A are arranged at substantially equal intervals. Furthermore, the diameters (opening sizes) of the plurality of holes 35A gradually increase in the +X direction (the direction from left to right in FIG. 6A ) and become the same diameter halfway through (for example, near the center). However, the diameters of all of the holes 35A may be the same, or the diameters may change linearly from left to right.

[0029] The plurality of holes 35B are arranged in a substantially aligned second row CB along the extension direction of the sound conduit 31 (the X direction in FIG. 6A ). The first row CA and the second row CB are substantially parallel rows along the extension direction of the sound conduit 31 and are adjacent rows. A second hole group 36B is formed by the plurality of holes 35B. The plurality of holes 35B are arranged at substantially equal intervals. Furthermore, the diameters (opening sizes) of the plurality of holes 35B gradually increase in the +X direction (the direction from left to right in FIG. 6A ) and become the same halfway through (for example, near the center). However, the diameters of all the holes 35B may be the same, or the diameters may change linearly from left to right. Note that the first row CA and the second row CB are components provided for convenience of explanation, and the first row CA and the second row CB do not necessarily have to be visible.

[0030] The individual holes 35A constituting the first hole group 36A and the individual holes 35B constituting the second hole group 36B are arranged, for example, in a staggered (zigzag) pattern.

[0031] The directional speaker 30 further includes a support member 37. The support member 37 is made of resin or metal and has, for example, a thin plate shape. The support member 37 is attached, for example, to the lower side of the sound conduit 31 and supports the entire sound conduit 31. The support member 37 has protrusions 37A and 37B that partially protrude from predetermined ends of the sound conduit 31. For example, two holes 38A are formed in the protrusion 37A. For example, two holes 38B are formed in the protrusion 37B. The directional speaker 30 is attached to the rear portion 13 by attaching screws or bolts to the rear portion 13 using the holes 38A and 38B. For example, the directional speaker 30 is attached to the rear portion 13 with the tip 32 of the sound conduit 31 facing upward (toward the upper peripheral portion 13A). As a result, the beam BM is emitted toward the rear side of the image display device 10 and diagonally upward.

[0032] The length of the directional speaker 30 (the length in the X direction in FIG. 6A ) is, for example, approximately 120 mm to 130 mm. The width of the directional speaker 30 (the length in the Y direction in FIG. 6A ) is, for example, approximately 75 mm to 85 mm. The thickness of the directional speaker 30 (the length in the Z direction in FIG. 6A ) is, for example, approximately 20 mm to 30 mm. Of course, the size of the directional speaker 30 is not limited to the above example. However, because electronic components that drive the image display device 10 are stored inside the image display unit 11 and various interfaces such as a USB (Universal Serial Bus) and an HDMI (High-Definition Multimedia Interface) (registered trademark) are provided on the rear surface unit 13, it is preferable that the directional speaker 30 be relatively small.

[0033] (Operation Example) Next, with reference to Figures 7A and 7B, an operation example of the directional speaker 30 will be described. Note that Figure 7A shows a simplified shape of the directional speaker 30.

[0034] Sound waves reproduced from the speaker unit 34 propagate through the internal space SP1 of the sound conduit 31. Then, sound waves are sequentially emitted from the hole 35A (and similarly for the hole 35B) closer to the open end 33. The sound waves radiated from the hole 35A and the like are subjected to the effects of propagation delay and attenuation within the sound conduit 31, and the radiated sound waves form directivity due to the phase interference of each wave. In other words, as sound is reproduced from each hole of the directional speaker 30, a directional sound beam BM is generated and radiated.

[0035] As shown in Fig. 7B , the vertical direction of the holes 35A, 35B (the direction of sound radiation, which is the direction of a perpendicular line extending from the center of each hole in the Z direction) is set to 0°. The direction of the sound radiation surfaces (opening surfaces of each hole) of the holes 35A, 35B toward the tip 32 of the sound conduit 31 is set to 90°. In this case, the directivity of the beam BM, which is schematically shown in Fig. 7A , i.e., the radiation direction, is within a range of 60° to 80°, as shown in Fig. 7B . In other words, the sound reproduced from the speaker unit 34 is reproduced diagonally upward from the directional speaker 30.

[0036] In this embodiment, the diameters of the plurality of holes 35A, 35B gradually increase from the side closer to the speaker unit 34 toward the tip 32. This configuration makes it possible to match the radiated sound pressures from the respective holes as much as possible, and to align the radiation direction (radiation direction of the beam BM) created by combining these, thereby increasing the sound pressure.

[0037] Furthermore, the shorter the spacing between the holes, the more likely it is that a sound beam BM spanning a wide frequency range can be generated. In a configuration in which multiple holes are arranged in a row, there is a limit to how short the spacing between the holes can be due to constraints imposed by the diameter of the holes, the space on the flat surface 31A, and manufacturing process constraints. However, in this embodiment, as described above, the holes 35A and holes 35B in each row are arranged in a staggered pattern. As a result, when the directional speaker 30 is viewed from the side, the holes 35A and holes 35B are alternately arranged, which allows the distance between the holes (e.g., the distance between the centers of the holes) to be reduced by approximately half. In other words, the apparent spacing between the holes can be shortened, making it possible to generate a sound beam BM spanning a wide frequency range.

[0038] The holes 35A and 35B may be inclined as a whole toward the radiation direction of the beam BM. For example, the holes 35A and 35B may be inclined at approximately 45 degrees diagonally upward. This can improve the sound pressure level of the beam BM. It can also reduce sound leakage components that do not form the beam BM.

[0039] [Location of Directional Speakers] In order to solve the above-mentioned problems, the appropriate location (range) of the directional speakers 30A and 30B was investigated.

[0040] First, the spacing between the directional speakers 30A and 30B was examined. As shown in FIG. 8 , the distance between the center lines of the directional speakers 30A and 30B was defined as the spacing distance HD. Note that in FIG. 8 and subsequent figures, the shapes of the directional speakers 30A and 30B are sometimes simplified and illustrated as rectangles. A 75-inch television set was used as the video display device 10. Specifically, the television set had a width of 1667 mm, a height of 961 mm, and a thickness of 61 mm. First, the directional speaker 30A was positioned near the right peripheral edge 13C, and the directional speaker 30B was positioned near the left peripheral edge 13D. Then, the directional speakers 30A and 30B were moved inward by the same distance, and the directional speakers 30A and 30B were temporarily attached to the rear surface 13, thereby changing the distance HD. Then, a predetermined test sound (e.g., a musical piece) was played from the directional speakers 30A and 30B, and the reflected sound image RSA formed on the ceiling CE by the beam BMA emitted from the directional speaker 30A and the reflected sound image RSB formed on the ceiling CE by the beam BMB emitted from the directional speaker 30B were measured using a known acoustic camera capable of visualizing sound pressure distribution. Note that, for ease of understanding, the measurement results using the acoustic camera only show the locations corresponding to the reflected sound images RSA and RSB. Furthermore, for the reflected sound images RSA and RSB, the locations shown are those where the sound pressure was 65 dB or higher, which is the general conversation level.

[0041] Fig. 9A shows the arrangement of directional speakers 30A and 30B when the distance HD is relatively large (for example, 1520 mm). Fig. 9B shows the sound pressure distribution of reflected sound images RSA and RSB measured by an acoustic camera in the arrangement shown in Fig. 9A.

[0042] As shown in Figure 9B, because the distance HD between the directional speakers 30A and 30B is too large, the reflected sound images RSA and RSB become separated. As a result, the sound image is not localized in the center, resulting in the hollow sound described above. As long as the distance HD is equal to or greater than a certain value, the reflected sound images RSA and RSB remain separated, as shown in Figure 9B.

[0043] Fig. 10A shows an arrangement of directional speakers 30A and 30B where the distance HD is 1050 mm. Fig. 10B shows the sound pressure distribution of reflected sound images RSA and RSB measured by an acoustic camera in the arrangement shown in Fig. 10A.

[0044] As shown in FIG. 10B , when the distance HD is 1050 mm, the reflected sound images RSA and RSB are separated by areas of high sound pressure. Therefore, the stereo effect of upward localization can be maintained. Furthermore, the positions at which the reflected sound images RSA and RSB are formed match the size (width) of the image display device 10. Furthermore, the reflected sound images RSA and RSB overlap at areas of a certain level of sound pressure (e.g., 65 dB or more and less than 80 dB), and a sound image is also present in the center. This prevents a hollow sound from occurring. Even when the distance HD is shortened from 1050 mm, the reflected sound image shown in FIG. 10B is formed for a certain distance.

[0045] Fig. 11A shows an arrangement of directional speakers 30A and 30B where the distance HD is 850 mm. Fig. 11B shows the sound pressure distribution of reflected sound images RSA and RSB measured by an acoustic camera in the arrangement shown in Fig. 11A.

[0046] As shown in Figure 11B, when the distance HD is 850 mm, all sound pressure areas of the reflected sound images RSA and RSB overlap and become one. The area with high sound pressure is formed near the center. In this way, the sound image with high sound pressure is formed near the center, which significantly emphasizes the sense of central localization. As a result, the stereo effect perceived by the user U in the upward localization is diminished.

[0047] From the above, it can be seen that the distance HD is preferably in the range of 850 mm to 1050 mm.

[0048] Next, the vertical position of the directional speaker 30 (directional speaker 30A and directional speaker 30B) was examined. The distance VD, which is the distance from the upper periphery 13A of the rear surface 13 to the upper end of the directional speaker 30, was changed. As shown in FIG. 12A , the center of the hole that contributes to sound reproduction and is closest to the tip 32 (hole 35A, in this example, closest to the tip 32) was set as the upper end of the directional speaker 30.

[0049] As shown in FIG. 12B , the usage mode in which the distance WD between the rear surface 13 and the wall RW is smallest is assumed to be a mode in which the image display device 10 is supported on the wall RW by a bracket 60 and wall-mounted. In this case, the distance WD is approximately 10 mm. Even when the image display device 10 is placed on a surface rather than wall-mounted, it is rare for the image display device 10 to be used in the center of an acoustic space such as a room. Rather, it is more common for the image display device 10 to be used close to the wall RW. In this case, the distance WD from the rear surface 13 to the wall RW is approximately 1 m at most. Although the reflective effect of the wall RW cannot be obtained when the distance WD from the rear surface 13 to the wall RW is extremely long, such cases are rare. Therefore, if it can be confirmed that the reflective effect of the wall RW can be obtained when the distance WD is smallest, it is considered that the reflective effect of the wall RW can be obtained even when the distance WD corresponds to a typical usage mode.

[0050] The actual measurements were performed as follows: As shown in Fig. 12C, the directional speakers 30 (directional speakers 30A and 30B) were fixed to the wall RW using a support member or the like (not shown). The distance WD between the directional speakers 30A and 30B and the wall RW was set to 10 mm for the reasons described above.

[0051] To facilitate measurement, in this example, a plate 70 was prepared that was approximately the same size and made of approximately the same material (e.g., resin) as the video display unit 11. The plate 70 was positioned so that its rear surface 73 (corresponding to the rear surface 13 of the video display unit 11) faced the directional speakers 30A and 30B. The plate 70 was then moved vertically to change the distance VD between the upper peripheral edge 73A of the plate 70 (corresponding to the upper peripheral edge 13A of the video display unit 11) and the hole 35A closest to the upper peripheral edge 73A. While changing the distance VD, a predetermined test sound (e.g., music) was played from the directional speakers 30A and 30B, and the reflected sound images RSA and RSB formed on the ceiling CE were measured using an acoustic camera. For ease of understanding, only the portions of the measurement results using the acoustic camera corresponding to the reflected sound images RSA and RSB are shown. Furthermore, for the reflected sound images RSA and RSB, the locations where the sound pressure was equal to or higher than 65 dB, which is the general conversation level, were shown. The distance HD between the directional speakers 30A and 30B was set to 1050 mm, which is one of the optimum values ​​mentioned above.

[0052] The distance VD was gradually increased from an initial value (for example, the distance VD = 0 or the value of the distance VD when the tip of the sound conduit 31 and the upper peripheral edge portion 73A were aligned). As shown in FIG. 13A, the distance VD was changed up to 130 mm. FIG. 13B shows the measurement results for the reflected sound images RSA and RSB when the distance VD was 130 mm. Up to the distance VD of 130 mm, the areas of high sound pressure (for example, 80 dB or more) in the reflected sound images RSA and RSB are clearly separated. Furthermore, the areas of a certain level of sound pressure (for example, 65 dB or more and less than 80 dB) in the reflected sound images RSA and RSB overlap, and a sound image is also present in the center. In other words, it can be seen that up to a distance VD of 130 mm, the beam BM emitted from the directional speakers 30A, 30B is reflected by the wall portion RW and then forms an appropriate reflected sound image (a sound image that provides a stereo feeling and suppresses center-off sounds) toward the upper side.

[0053] On the other hand, it was found that when the distance VD is greater than 130 mm, in other words, when the directional speakers 30A, 30B are positioned lower, the sound pressure decreases. For example, as shown in FIG. 14A, the distance VD is set to 215 mm. The measurement results using an acoustic camera in this case are shown in FIG. 14B. As shown in FIG. 14B, the reflected sound images RSA and RSB are formed on the left and right, and a sound image is also formed in the center due to the overlapping portion of the reflected sound images RSA and RSB. This is because the distance HD between the directional speakers 30A and 30B is an appropriate value, and the distribution of the reflected sound images RSA and RSB itself is thought to be appropriate.

[0054] However, when the reflected sound images RSA and RSB shown in FIG. 14B are viewed from the perspective of sound pressure, even the point where the sound pressure is greatest is 80 dB or less. In other words, the sound pressure is approximately 7 dB to 10 dB lower than the sound pressure of the reflected sound images RSA and RSB when the distance VD is 130 mm or less. This reduction in sound pressure makes it difficult for the user U to obtain a sense of positioning above. Therefore, it was found that the value of the distance VD is preferably greater than the initial value and equal to or less than 130 mm.

[0055] From the above, the preferred placement position for the pair of directional speakers 30A, 30B is when the distance between them is 850 mm or more and 1050 mm or less, and when the distance from the upper peripheral portion 13A to each of the directional speakers 30A, 30B is 130 mm or less.

[0056] When a pair of directional speakers is placed in this preferred position, if a sound beam emitted to the outside through the holes of each directional speaker is emitted toward a wall installed 10 mm away from the rear portion, the beam is reflected by the wall, forming a reflected sound image in a direction approximately perpendicular to the video display unit. Such reflected sound images include a pair of sound images (separate sound images) formed corresponding to each of the pair of directional speakers, each with a predetermined sound pressure (e.g., 80 dB) or more, and a sound image formed between at least the pair of sound images (a sound image formed by the action of directional speaker 30A and a sound image formed by the action of directional speaker 30B overlapping each other), with a sound pressure lower than the predetermined value.

[0057] In this example, a 75-inch equivalent video display unit 11 was used. The results obtained in this example are believed to be similarly applicable to equivalent video display units 11 with a substantially different size (for example, within the range of 65 to 85 inches).

[0058] <Modifications> Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present disclosure.

[0059] For example, as shown in FIG. 15 , the sizes of the holes 35A and 35B may be different. For example, the size of the hole 35A on the open end 33 side may be made larger than the size of the hole 35B on the open end 33 side. Furthermore, the size change step of the hole 35A may be made larger than the size change step of the hole 35B. For example, by making the size of the hole 35A larger than the size of the hole 35B, the sound pressure of the sound radiated from the hole 35A can be made larger than the sound pressure of the sound radiated from the hole 35B. This makes it possible to increase the sound pressure inside or outside the beam BM generated by the sound radiated from each hole. By making the sound pressure of the beam BM partially different, it is possible to improve the sound field collapse, such as the above-mentioned hollows and crests.

[0060] In the above-described embodiment, the hole portions are provided along two rows of the plate-shaped portion. However, the hole portions may be provided along three or more rows. In this case, the hole portions along each row may be arranged in a staggered pattern. Furthermore, the plurality of hole portions may be arranged to form a ring or a rectangle rather than a row. Furthermore, in the above-described embodiment, the diameter of the hole portions gradually increases. However, the diameter may increase for each unit of a plurality of hole portions. Furthermore, although the above-described advantages can be obtained by arranging the hole portions in a staggered pattern, the hole portions may also be arranged adjacent to each other instead of in a staggered pattern.

[0061] In the above-described embodiment, the directional speaker 30 has been described as an example of a speaker having directionality, but the present invention is not limited to this and a directional speaker having another shape may be used. The directional speaker may be, for example, a horn speaker having a predetermined directivity.

[0062] Furthermore, the matters described in each embodiment and modification can be combined as appropriate. Furthermore, the contents of the present disclosure should not be interpreted as being limited to the effects exemplified in this specification.

[0063] The present disclosure may also adopt the following configurations: (1) An image display device comprising: an image display unit having an image display surface and a rear surface opposite to the image display surface; and a pair of directional speakers provided on the rear surface, wherein the distance between the pair of directional speakers is 850 mm or more and 1050 mm or less, and the distance from an upper peripheral edge of the rear surface to the directional speakers is 130 mm or less. (2) The image display device described in (1), wherein each of the pair of directional speakers comprises: a speaker unit; a hollow sound conduit having one closed end and the other open end to which the speaker unit is attached; and a plurality of holes provided in the sound conduit, wherein sound reproduced from the speaker unit is radiated from inside the sound conduit to the outside through the holes. (3) The image display device according to (2), wherein, when the vertical direction of the hole is 0° and the direction of the sound emission surface of the hole toward the one end of the sound conduit is 90°, the emission direction of the beam generated by the sound radiated from the plurality of holes is in the range of 60° to 80°. (4) The image display device according to any of (1) to (3), wherein the plurality of holes are arranged in a general alignment along the extension direction of the sound conduit. (5) The image display device according to (4), wherein diameters of the plurality of holes increase from the side closer to the speaker unit toward the one end and become generally the same diameter from a predetermined point. (6) The image display device according to (4) or (5), wherein the plurality of holes include a first group of holes arranged in a general alignment in a first row along the extension direction of the sound conduit, and a second group of holes arranged in a general alignment in a second row along the extension direction of the sound conduit. (7) The image display device according to (6), wherein the individual holes constituting the first hole group and the individual holes constituting the second hole group are arranged in a staggered pattern. (8) The image display device according to any one of (1) to (7), wherein the size of the image display unit is within a range of 65 inches to 85 inches.(9) The video display device according to any one of (2) to (8), wherein, when a sound beam emitted to the outside through the hole is emitted toward a wall portion installed at a position 10 mm away from the rear portion, the beam is reflected by the wall portion, thereby forming a reflected sound image in a direction approximately vertical to the video display portion. (10) The video display device according to (9), wherein the reflected sound images include a pair of sound images formed corresponding to each of the pair of directional speakers when the sound pressure is equal to or higher than a predetermined value, and a sound image formed at least between the pair of sound images when the sound pressure is lower than the predetermined value. (11) The video display device according to any one of (1) to (10), wherein the speaker unit is a tweeter unit that reproduces high-frequency sound equal to or higher than a predetermined frequency. (12) The video display device according to (11), wherein the high-frequency sound equal to or higher than the predetermined frequency includes sound of 5 kHz or higher. (13) The video display device according to (11) or (12), wherein a signal that has passed through a high-pass filter having a cutoff frequency of the predetermined frequency is reproduced from the speaker unit. (14) The video display device according to any one of (1) to (13), wherein one of the pair of directional speakers is a directional speaker corresponding to an L channel, and the other is a directional speaker corresponding to an R channel.

[0064] REFERENCE SIGNS LIST 1: Sound reproduction system 10: Image display device 11: Image display section 12: Image display surface 13: Rear section 30, 30A, 30B: Directional speaker 31: Sound guide tube 32: Tip section 33: Open end 35A, 35B: Hole section 36A: First hole section group 36B: Second hole section group CA: First row CB: Second row BM: Beam RW: Wall section

Claims

1. A video display device comprising: a video display unit having a video display surface and a rear surface opposite the video display surface; and a pair of directional speakers provided on the rear surface, wherein the distance between the pair of directional speakers is 850 mm or more and 1050 mm or less, and the distance from the upper periphery of the rear surface to the directional speakers is 130 mm or less.

2. The image display device of claim 1, wherein each of the pair of directional speakers comprises a speaker unit, a hollow sound guide tube with one end closed and the other end open to which the speaker unit is attached, and a plurality of holes provided in the sound guide tube, and wherein sound reproduced from the speaker unit is radiated from inside the sound guide tube to the outside through the holes.

3. The image display device according to claim 2, wherein, when the vertical direction of the hole is 0° and the direction of the sound emitting surface of the hole toward the one end of the sound guide tube is 90°, the radiation direction of the beam generated by the sound radiated from the plurality of holes is in the range of 60° to 80°.

4. The image display device according to claim 1, wherein the plurality of holes are arranged in a substantially aligned manner along the extension direction of the sound guide tube.

5. The image display device according to claim 4, wherein the diameters of the plurality of holes increase from the side closer to the speaker unit toward the one end, and become substantially the same diameter from a predetermined point.

6. An image display device as described in claim 4, wherein the plurality of holes include a first group of holes arranged in approximately alignment with a first row along the extension direction of the sound conduit, and a second group of holes arranged in approximately alignment with a second row along the extension direction of the sound conduit.

7. The image display device according to claim 6, wherein the individual holes constituting the first hole group and the individual holes constituting the second hole group are arranged in a staggered pattern.

8. The image display device according to claim 1, wherein the size of the image display unit is within the range of 65 to 85 inches.

9. The image display device according to claim 2, wherein when a sound beam emitted to the outside through the hole is emitted toward a wall portion installed at a position 10 mm away from the rear portion, the beam is reflected by the wall portion, thereby forming a reflected sound image in a direction approximately vertical to the image display portion.

10. A video display device as described in claim 9, wherein the reflected sound images include a pair of sound images formed corresponding to each of the pair of directional speakers when the sound pressure is equal to or greater than a predetermined value, and a sound image formed at least between the pair of sound images when the sound pressure is smaller than the predetermined value.

11. The video display device according to claim 1, wherein the speaker unit is a tweeter unit that reproduces high-frequency sounds above a predetermined frequency.

12. The image display device according to claim 11, wherein the high-frequency sounds above the predetermined frequency include sounds above 5 kHz.

13. The video display device according to claim 11, wherein a signal that has passed through a high-pass filter whose cutoff frequency is the predetermined frequency is reproduced from the speaker unit.

14. The video display device according to claim 1, wherein one of the pair of directional speakers is a directional speaker corresponding to the L channel, and the other is a directional speaker corresponding to the R channel.

Images