Audio output device and audio output method

Abstract

To make video match an audio playback position to thereby make an audiovisual environment more comfortable.SOLUTION: An audio output device comprises a first speaker that is a directional speaker arranged toward a video display surface, a second speaker which is wider in directivity than at least the first speaker, and an audio signal processing part. The audio signal processing part extracts a signal component at a high-frequency band side of an audio signal outputted together with video displayed on the video display surface to generate a first audio signal that is supplied to the first speaker; and also extracts a signal component closer to a low-frequency band side than the first audio signal of the audio signal outputted together with the video displayed on the video display surface and performs delay processing to the component to generate a second audio signal that is supplied to the second speaker.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present technology relates to an audio output device and an audio output method for outputting audio to be played together with video. [Background technology]

[0002] Patent Document 1 below is a technology related to sound that is played simultaneously with an image projected by a projector onto a wall or screen. This technology discloses that sound emitted from a specific channel, for example a surround channel, in an audio device placed near the screen is reflected from the screen, wall, ceiling, etc. to the viewer's position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 10,863,276 Summary of the Invention [Problem to be solved by the invention]

[0004] There are devices called mobile projectors or portable projectors that combine image projection and audio playback. Because they have a built-in audio playback function, users can experience movies and other content with both image and audio simply by setting up such a projector anywhere.

[0005] However, because audio is output from speakers inside the projector body, if the projector is placed away from the display surface of the projected image, the playback positions of the image and audio may differ, which may cause discomfort to the user. Even when sound is output from a separate speaker, the sound may not be localized on the image display screen, causing a sense of discomfort.

[0006] Therefore, an object of the present technology is to match the playback positions of video and audio, thereby enabling users to experience video and audio with a sense of realism. [Means for solving the problem]

[0007] The audio output device of the present technology includes a first speaker which is a directional speaker arranged facing a video display surface, a second speaker having a directionality at least wider than that of the first speaker, and an audio signal processing unit which extracts signal components on the high frequency band side of an audio signal to be output together with an image to be displayed on the video display surface to provide a first audio signal to be supplied to the first speaker, and extracts signal components including a lower frequency band side than the first audio signal from the audio signal to be output together with the image to be displayed on the video display surface, performs delay processing, and provides a second audio signal to be supplied to the second speaker. With this configuration, of the sounds accompanying the video, the higher frequency sounds are output from the first speaker, reflected by the video display surface and reach the viewer, while the lower frequency sounds are delayed before reaching the viewer. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of a state in which a projector according to a first embodiment of the present technology is in use. [Diagram 2] FIG. 11 is an explanatory diagram of a state in which a projector of a comparative example is used. [Diagram 3] 4A and 4B are explanatory diagrams of high-frequency characteristics and low-mid-frequency characteristics of output sound according to the embodiment; [Figure 4] FIG. 1 is an explanatory diagram illustrating an example of the appearance of a projector according to an embodiment. [Diagram 5] FIG. 1 is an explanatory diagram illustrating an example of the appearance of a projector according to an embodiment. [Figure 6] FIG. 2 is an explanatory diagram of the Haas effect according to the embodiment. [Figure 7] FIG. 2 is an explanatory diagram of an example of a monaural channel according to an embodiment. [Figure 8] FIG. 2 is an explanatory diagram of an example of three channels according to an embodiment. [Figure 9]4 is an explanatory diagram of a radiation angle of high-frequency sound according to an embodiment. FIG. [Figure 10] 1 is a block diagram of a sound output device according to an embodiment; [Figure 11] 11 is a flowchart of a calibration process according to the embodiment. [Figure 12] 1 is an explanatory diagram of a phase interference type narrow-directivity speaker that can be applied to an embodiment. [Figure 13] 1 is an explanatory diagram of a parabolic narrow-directivity speaker that can be applied to an embodiment. [Figure 14] 1 is an explanatory diagram of an ultrasonic narrow-directivity speaker that can be applied to an embodiment. [Figure 15] FIG. 11 is an explanatory diagram of a usage state of a short focus projector according to a second embodiment. [Figure 16] FIG. 11 is an explanatory diagram of a speaker configuration of a short focus projector according to a second embodiment. [Figure 17] 13A to 13C are explanatory diagrams illustrating a state in which the bar-shaped speaker according to the third embodiment is in use. [Figure 18] 13 is an explanatory diagram of a speaker configuration of a bar-shaped speaker according to a third embodiment. FIG. [Figure 19] FIG. 13 is a perspective view of a ceiling mounted projector according to a fourth embodiment. [Figure 20] FIG. 13 is an explanatory diagram of a state in which a ceiling mounted projector according to a fourth embodiment is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The embodiments will be described below in the following order. <1. First embodiment: Portable projector> <2. Second embodiment: short focus projector> <3. Third embodiment: Bar-shaped speaker> <4. Fourth embodiment: Ceiling-mounted projector> <5. Summary and examples of modifications>

[0010] <1. First embodiment: Portable projector> 1 shows a first embodiment of the present invention in which video content is viewed using a projector 1. The projector 1 in this case is a relatively small device known as a portable projector or mobile projector.

[0011] The portable projector 1 is constructed in a relatively small housing and can be carried around by the user. Since it also has a built-in speaker and battery, the user can set up the projector 1 anywhere and project images onto a wall or screen 150, allowing the user to experience content such as movies with video and audio.

[0012] 1, the projector 1 is installed, for example, near a viewer 120, and emits projection light 101 to display an image 110 on a screen 150. This forms an image display surface 111 on the screen 150. Furthermore, sound reproduced together with the image 110 is output from a speaker built into the projector 1.

[0013] Before describing the audio output in the embodiment, a comparative example will be described with reference to Fig. 2. Like Fig. 1, Fig. 2 also shows a state in which a projector 300 is installed and an image 110 is projected onto a screen 150. Audio is output from a speaker built into the projector 300. In this case, the viewer 120 recognizes the image 110 on the image display surface 111 as indicated by the arrow 100, but perceives the sound as coming from the direction of the projector 300 as indicated by the arrow 210. For this reason, the positions of the image 110 and the sound 211 do not match for the viewer 120. For example, in content such as a movie, the voice of an actor in the image 110 speaking will sound as if it is coming from the side, not from the direction of the image, which creates a sense of discomfort for the viewer 120.

[0014] Therefore, in this embodiment, a device is devised for audio reproduction as shown in FIG. FIG. 1 shows an example of a two-channel configuration for audio output, an L (left) channel and an R (right) channel. The projector 1 outputs low-mid range sound 203 with wide directivity to the surroundings, while outputting high range sound 201 toward the image display surface 111. In particular, by arranging a narrow directivity speaker so that it faces the image display surface 111, the high range sound 201 is emitted toward the image display surface 111. This high range sound 201 is reflected by the screen 150. The reflected high range sound 202 reaches the viewer 120 and is heard by the viewer 120. Therefore, the viewer 120 recognizes the image display surface 111 as the sound emission position (virtual speaker position) for the reflected high range sound 202.

[0015] On the other hand, the mid-low range sound 203 is output as sound from, for example, an omnidirectional speaker built into the projector 1, or a speaker having a relatively wide directivity. In this case, the projector 1 outputs the low-mid range sound 203 with a predetermined delay, so that the reflected high-range sound 202 reaches the viewer 120 slightly earlier than the low-mid range sound 203 .

[0016] In this case, the high-frequency audio 201 (reflected high-frequency audio 202) is timed to match the video 110. For example, the audio is made to match the video content, such as the voices and movements of the actors in the video 110. It is sufficient to match the output timing of the high-frequency audio 201 from the high-frequency speaker 3 with the video content, but the output timing of the high-frequency audio 201 may also be set to match the reflected high-frequency audio 202 with the video content, taking into consideration the distance to reach the viewer 120. In contrast, the low-mid-range sound 203 is perceived slightly later by the viewer 120. Then, due to the Haas effect (precedence effect), the sound image is localized for the viewer 120 in the direction of the reflected high-range sound 202 that arrived first. In other words, it is in the direction of the image display surface 111 on which the image 110 is displayed. And because the reflected high-frequency sound 202 arrives from the direction of the image 110 without any delay relative to the image, the viewer 120 perceives the sound as if it is being output from within the image 110. Furthermore, with the addition of the low-mid-range sound 203, the viewer 120 perceives a powerful sound as if it is being emitted from the image display surface 111.

[0017] In this way, even if the portable projector 1 is installed in an arbitrary position, the viewer 120 feels that the playback positions of the video and audio are aligned, and can experience video and audio with a sense of realism.

[0018] The projector 1 will be specifically described below. FIG. 3 shows frequency characteristics of a high-frequency sound 201 and a low-mid-frequency sound 203. A certain cutoff frequency fc is set, and signal components on the high frequency band side are extracted by filter processing to produce high frequency sound 201. Signal components on the low frequency band side below the cutoff frequency fc are also extracted by filter processing to produce low mid frequency sound 203. Figure 3 shows high frequency characteristics 161 and low mid frequency characteristics 162 in this case.

[0019] The cutoff frequency fc may be, for example, around 3 KHz. Although 3 KHz is one example, it is preferable that the high-frequency sound 201 includes the band between 5 KHz and 7 KHz, which is a band to which humans are sensitive. On the other hand, if only a specific narrow band is included, it may be felt that a double sound is heard between the component reflected on the screen and the component that reaches the viewer 120 directly from the main body, so it is preferable to make the band as wide as possible. Therefore, it is possible to consider a band higher than 3 KHz, for example, as the high-frequency sound 201, which includes around 5 KHz to 7 KHz and means as wide a band as possible. Of course, examples of the high-frequency sound 201 being higher than 4 KHz or higher than 5 KHz are also possible.

[0020] The cutoff frequency fc may be variably set. For example, it may be changed by a user operation, or it may be adjusted by the material of the image display surface 111, etc., taking into account the reflection characteristics.

[0021] In addition, in the embodiment, the high and low frequencies are separated at around 3 KHz, for example, and the separation into a "high frequency" and a "mid-low frequency" is described; however, examples of separation into, for example, a "high and mid frequency" and a "low frequency" are also conceivable.

[0022] The projector 1 outputs the band-divided high-frequency sound 201 and low-mid-frequency sound 203. Fig. 4 is a schematic diagram showing the configuration of the projector 1 in the case of a monaural channel.

[0023] The projector 1 has a projection unit 2 that outputs projection light 101 formed on the screen side surface of the housing. The high-frequency speaker 3 with narrow directivity is provided so as to emit sound, for example, in the projection direction of the projection unit 2. As a result, the high-frequency sound 201 from the high-frequency speaker 3 is directed toward the image display surface 111 and is reflected.

[0024] The mid-low range speaker 4 is provided inside the housing of the projector 1, or on a surface of the housing different from the projection unit 2. For example, sound from the mid-low range speaker 4 inside the housing is emitted through a sound emission hole 6. Also, sound from the mid-low range speaker 4 provided on a surface on the housing is emitted from the surface of the housing. Since the mid-low range speaker 4 is omnidirectional or has wide directivity, the mid-low range sound 203 reaches the surrounding viewers 120 directly.

[0025] 5 is a schematic diagram showing the configuration of the projector 1 in the case of L-R stereo channels. Narrow-directivity high-frequency speakers 3 for the L channel and R channel are provided so as to emit sound toward the projection direction of the projection unit 2. As a result, high-frequency sounds 201 for the L channel and R channel from the high-frequency speakers 3, 3 are directed toward the image display surface 111 and are reflected therefrom. The mid-low range speakers 4 correspond to the L channel and the R channel, respectively, and are provided inside the housing of the projector 1 or on a surface of the housing different from the projection unit 2.

[0026] The above-mentioned Figs. 4 and 5 are merely schematic examples, and various shapes of the projector 1, the number of speakers, the number of channels, speaker arrangement configurations, etc. are possible.

[0027] For example, the Haas effect caused by the above-described projector 1 will be described with reference to FIG. FIG. 6 shows a state in which high-frequency sound 201 from the high-frequency speakers 3 of the L channel and R channel is reflected by the image display surface 111 on the screen 150, and the sound of the L channel (Lch) and R channel (Rch) reaches the viewer 120 as reflected high-frequency sound 202. Furthermore, the low-mid-range sound 203 reaches the viewer 120 directly from the low-mid-range speaker 4 . At this time, the Haas effect is obtained by delaying the mid-low frequency sound 203 by a time difference ΔT with respect to the reflected high frequency sound 202. This makes the viewer 120 feel as if the sound image is localized on the image display screen 111.

[0028] In addition, the high-frequency sound 201 (high-frequency speaker 3) may be configured as a mono channel or a three-channel configuration of an L channel, an R channel, and a C (center) channel (Cch) other than the L / R two-channel configuration. It may also be configured as a multi-channel configuration of four or more channels. FIG. 7 shows a case where the high-frequency sound 201 is a monaural channel, and FIG. 8 shows a case where the high-frequency sound 201 is a three-channel configuration. In either case, the low-mid range sound 203 is delayed by a time difference ΔT with respect to the reflected high range sound 202 of one or more channels.

[0029] Although only one mid-low range speaker 4 is shown in each of the examples of Figs. 6, 7 and 8, the mid-low range speaker 4 may adopt a two-channel or three-channel stereo speaker configuration.

[0030] Incidentally, when high-frequency speakers 3 are arranged for two channels, L and R, each high-frequency speaker 3 may be fixedly arranged facing a respective predetermined direction. FIG. 9A shows a case where the projector 1 and the screen 150 are relatively close, and FIG. 9B shows a case where the projector 1 and the screen 150 are relatively far away.

[0031] In this case, the high-frequency speaker 3 of the L channel is fixedly positioned so that the high-frequency audio 201 is output toward the left area of ​​the video display surface 111, and the high-frequency speaker 3 of the R channel high-frequency audio 201 is fixedly positioned so that the high-frequency audio 201 is output toward the right area of ​​the video display surface 111. In this case, the two high-frequency speakers 3, 3 are arranged to have a radiation angle AG1. The radiation angle AG1 is determined based on the radiation angle AG2 of the projected light 101. In other words, if the high-frequency speakers 3, 3 are arranged so that the radiation angle AG1 is within the angular range of the radiation angle AG2 and slightly smaller than the radiation angle AG2, the high-frequency sound 201 of the L channel will be directed toward the left region in the image 110, and the high-frequency sound 201 of the R channel will be directed toward the right region in the image 110. Therefore, for the viewer 120 , the reflected high-frequency sound 202 in the L channel is heard from the left area of ​​the image 110 , and the reflected high-frequency sound 202 in the R channel is heard from the right area of ​​the image 110 .

[0032] When the projector 1 and the screen 150 are relatively close as in FIG. 9A, the area of ​​the image 110 is small, and when the projector 1 and the screen 150 are relatively far away as in FIG. 9B, the area of ​​the image 110 is large. Considering this, for example, if the high-frequency speakers 3, 3 are arranged in a relationship of radiation angle AG1, the high-frequency sounds 201 of the L channel and R channel will be reflected in the left and right areas of the image 110 regardless of the position of the projector 1, that is, regardless of the distance from the image display surface 111. Therefore, when arranging high-frequency speakers 3 for two channels, L and R, each high-frequency speaker 3 only needs to be fixedly positioned so that it faces in a specified direction and has a radiation angle AG1, and there is no need to adjust the orientation of the high-frequency speakers 3, 3 according to the placement position of the projector 1.

[0033] In the case of a monaural channel, one high-frequency speaker 3 may be disposed so as to emit sound toward the center of the image display surface 111 , that is, toward the central axis direction of the projection light 101 . In addition, in the case of three channels, L, R, and C, the high-frequency speakers 3, 3 of the L channel and R channel are positioned in relation to the radiation angle AG1 as described above, and the high-frequency speaker 3 of the C channel is positioned so that it emits sound toward the central axis of the projection light 101.

[0034] An example of the configuration of an audio output device 90 built into the projector 1 will be described with reference to FIG. The audio output device 90 includes an audio source 20, an audio signal processing unit 21, an amplifier 22, an adjustment control unit 23, and a detection unit 24.

[0035] The audio source 20 indicates a source of an audio signal for audio to be played along with the projected image. For example, the audio source 20 can be a recording medium on which an audio signal of an audio track of video content is recorded, a communication unit for receiving video content by streaming or the like, or an input unit for inputting an audio signal from another device. The audio signal SI to be output is supplied from the audio source 20 to the audio signal processing unit 21.

[0036] In addition, the audio signal is shown as monaural in Fig. 10 to avoid complicating the drawing. In the case of the above-mentioned two-channel or three-channel, it is sufficient that the system of the illustrated audio signal has two or more channels. Furthermore, the number of channels of the high-frequency sound 201 output from the high-frequency speaker 3 may be different from the number of channels of the low-mid-frequency sound 203 output from the low-mid-frequency speaker 4. For example, the high-frequency sound 201 is output in two channels, L and R, and the low-mid-frequency sound 203 is output in monaural.

[0037] The audio signal processing unit 21 is configured by, for example, a DSP (digital signal processor) and performs necessary audio signal processing. In the case of this embodiment, as shown in the figure, the processing functions of the DSP include a low pass filter (LPF) 31, a high pass filter (HPF) 32, a delay unit 33, and an equalizer 34. The LPF 31 and HPF 32 perform filtering using the cutoff frequency fc shown in FIG.

[0038] The audio signal processing unit 21 extracts low-mid frequency audio signal components from the input audio signal SI using the LPF 31 and extracts high frequency audio signal components using the HPF 32 . The low-mid frequency audio signal component extracted by the LPF 31 is subjected to a delay process for a predetermined time by the delay unit 33, and is then output from the audio signal processing unit 21 as a low-mid frequency audio signal SML. This low-mid-range audio signal SML is amplified by the amplifier 22 and outputted as low-mid-range audio 203 from the low-mid-range speaker 4 .

[0039] The high-frequency components extracted by the HPF 32 have their sound pressure frequency characteristics adjusted by the equalizer 34, and are output as a high-frequency audio signal SH from the audio signal processing unit 21. Note that the output of the HPF 32 may be output as it is from the audio signal processing unit 21 as the high-frequency audio signal SH without providing the equalizer 34. This high-frequency audio signal SH is amplified by the amplifier 22 and outputted as high-frequency audio 201 from the high-frequency speaker 3 .

[0040] With the above configuration, the high-frequency audio signal SH is supplied to the high-frequency speaker 3 with narrow directivity, and the high-frequency audio 201 is output toward the video display screen 111. The delayed low-mid frequency audio signal SML is supplied to a low-mid frequency speaker 4 such as an omnidirectional speaker, and a low-mid frequency audio 203 is output. This allows the above-mentioned Haas effect to be exerted, and the sound image to be localized on the image display surface 111.

[0041] In addition, FIG. 10 shows an adjustment control unit 23, which allows adjustment to be made so that an appropriate Haas effect can be obtained depending on the situation. The adjustment control unit 23 may be configured, for example, by a processor such as a microcomputer separate from the audio signal processing unit 21, or may be configured, for example, by a DSP integrated with the audio signal processing unit 21.

[0042] The adjustment control unit 23 can instruct the audio signal processing unit 21 on the delay time DS calculated using the detection information of the detection unit 24 or the like, and perform a calibration process to optimize the delay time of the delay unit 33 . In addition, the adjustment control unit 23 can instruct the audio signal processing unit 21 on the correction value EQP calculated using the detection information of the detection unit 24, etc., and perform a calibration process to adjust the sound pressure frequency characteristics given to the high-frequency components by the equalizer 34.

[0043] FIG. 11 illustrates an example of the calibration process performed by the adjustment control unit 23. In step S101, the adjustment control unit 23 determines whether or not it is time for calibration. For example, the adjustment control unit 23 determines the timing for calibration when the projector 1 is turned on, when image projection starts, or when a user operation is performed, etc. If it is determined that it is the timing for calibration, the adjustment control unit 23 proceeds to step S102 and executes the calibration process of FIG.

[0044] Steps S102 to S105 are processes for adjusting the delay time of the delay unit 33. In step S102, the adjustment control unit 23 acquires detection information relating to distance from the detection unit 24. In step S103, adjustment control unit 23 calculates the distance from its own projector 1 to image display surface 111 or a time corresponding to the distance based on the detection information related to the distance input from detection unit 24. The time corresponding to the distance is a time calculated using the speed of sound.

[0045] In step S104, the adjustment control unit 23 calculates an appropriate delay time of the mid-low range audio signal SML to obtain the Haas effect based on the calculated distance. That is, the delay time DS is calculated as the time it takes for the audio output from the high range speaker 3 to be reflected by the image display surface 111 and return to the projector 1 itself, that is, the time required for a round trip over the calculated distance, plus the time difference ΔT in FIG. 6.

[0046] In step S105, the adjustment control unit 23 instructs the delay unit 33 of the audio signal processing unit 21 about the calculated delay time DS. This allows the delay unit 33 to perform delay processing using the delay time DS.

[0047] The optimum value of the delay time for obtaining the Haas effect while avoiding an unnatural feeling changes slightly depending on the position where the projector 1 is placed, specifically the distance to the image display surface 111 such as the screen 150. In the case of a portable projector 1, it is uncertain whether the user will place the projector 1 at such a distance. Therefore, by adjusting the delay time based on the distance detection, appropriate sound image localization due to the Haas effect can be realized regardless of where the viewer 120 places the projector 1 in a room or the like.

[0048] Here, the configuration of the detection unit 24 and an example of how the delay time DS is calculated using the detection unit 24 will be described. First, it is possible to provide a distance measurement sensor as the detection unit 24. For example, a distance measurement sensor such as a ToF (Time of Flight) sensor is disposed so as to be able to measure the distance in front of the projection unit 2. The distance between the projector 1 and the image display surface 111 can be detected by the detection information of this distance measurement sensor. Based on this, the time difference ΔT can be added to the time required for the round trip to obtain the delay time DS.

[0049] Furthermore, a focus control unit of the projection unit 2 that projects an image may be applied as the detection unit 24. In other words, the detection unit 24 is a focus information detection unit that acquires focus information of the projected image. For example, by using the focal length at a certain point in time and the defocus value in that state as focus information, the distance between the projector 1 and the image display surface 111 can be detected. Based on this, the time difference ΔT can be added to the time required for the round trip to find the delay time DS. The distance measurement sensor may be an autofocus distance measurement sensor. In that case, distance measurement information is detected as focus information, and an appropriate delay time DS can be calculated using the distance measurement information.

[0050] It is also possible to provide a microphone as the detection unit 24. For example, at the time of step S102, the adjustment control unit 23 controls so that a predetermined high-frequency audio signal SH is output from the high-frequency speaker 3. Then, the sound is collected by the microphone as the detection unit 24, and an audio signal is input. The time required for the round trip can be determined by calculating the time difference between the output timing of this high-frequency audio signal SH and the audio signal collected by the microphone. Then, the delay time DS can be calculated by adding the time difference ΔT to the time required for the round trip.

[0051] Also, the detection unit 24 may be provided with an operation detection unit that detects an operation input by the user. For example, at the time of step S102, the adjustment control unit 23 detects the user input. When the user places the projector 1, the user inputs the distance to the screen 150. For example, the user may input an actual measurement, or may input a rough distance based on visual estimation. Based on the input distance, the adjustment control unit 23 can calculate the delay time DS by adding a time difference ΔT to the time required for a round trip.

[0052] 11, the adjustment control unit 23 further performs the processes of steps S106 to S108. This is adjustment processing related to the equalizer 34.

[0053] In step S106, the adjustment control unit 23 acquires detection information relating to the display surface type from the detection unit 24 and performs a determination of the image display surface 111. In step S107, the adjustment control unit 23 calculates a correction value EQP of the sound pressure frequency characteristic for the high-frequency sound 201 based on the determined type of the image display surface 111.

[0054] In step S108, the adjustment control unit 23 indicates the calculated correction value EQP to the equalizer 34 of the audio signal processing unit 21. This allows the equalizer 34 to perform sound pressure frequency processing based on the correction value EQP.

[0055] The high-frequency sound 201 is reflected by the image display surface 111 and reaches the viewer as reflected high-frequency sound 202. In this case, the sound pressure frequency characteristics of the reflected high-frequency sound 202 may change depending on the material of the screen 150 and the wall that constitute the image display surface 111. Therefore, in the above processing, a correction value EQP is calculated taking into account changes in the sound pressure frequency characteristics depending on the material of the image display surface 111 at that time, so that the sound pressure frequency characteristics of the reflected high-frequency audio 202 become the sound pressure frequency characteristics originally intended by the high-frequency audio signal SH.

[0056] That is, a correction value EQP is calculated so as to give an inverse characteristic of the change in the sound pressure frequency characteristic of the reflected high-frequency sound 202, and the high-frequency sound signal SH is equalized by the equalizer 34. For example, when attenuation occurs in a certain band, equalization is performed so that the band is boosted in advance. Then, the high-frequency sound 201 is output from the high-frequency speaker 3. When this high-frequency sound 201 is reflected by the image display surface 111, a change occurs in the sound pressure frequency characteristics. However, by previously providing an inverse characteristic using the correction value EQP, the reflected high-frequency sound 202 has the sound pressure frequency characteristics originally intended by the high-frequency sound signal SH.

[0057] By adaptively adjusting such correction value EQP of the sound pressure frequency characteristic, sound reproduction unaffected by the material of the image display surface 111, etc., can be realized. The configuration of the detection unit 24 for adjusting such sound pressure frequency characteristics and an example of calculation of the correction value EQP using the same will be given below.

[0058] First, it is conceivable to provide an imaging unit (image sensor) as the detection unit 24. For example, the imaging unit is disposed so as to capture an image in front of the projection unit 2. The wall and screen 150 constituting the image display surface 111 are reflected in the image obtained by this imaging unit. The adjustment control unit 23 performs object recognition processing on the captured image to determine what material the image display surface 111 is made of. For example, it determines whether it is a wall or a screen by image recognition. In some cases, it may be possible to detect the type of screen, the material of the wall, etc. Since the change in sound pressure frequency characteristic due to the material of the reflecting surface can be specified in advance, for example, if a correction value EQP according to the material is stored, the correction value EQP can be obtained from the type and material determination results.

[0059] It is also possible to provide a microphone as the detection unit 24. For example, at the time of step S102, the adjustment control unit 23 controls so that a predetermined high-frequency audio signal SH is output from the high-frequency speaker 3. Then, the sound is collected by the microphone as the detection unit 24, and an audio signal is input. By performing a sound pressure frequency analysis of the audio signal collected by the microphone and comparing it with the sound pressure frequency characteristic of the original high-frequency audio signal SH, it is possible to detect a change in the sound pressure frequency characteristic according to the material of the image display surface 111. Then, a correction value EQP that is the inverse characteristic of the change in the sound pressure frequency characteristic can be obtained.

[0060] The detection unit 24 may also be provided with an operation detection unit that detects an operation input by the user. For example, at the time of step S102, the adjustment control unit 23 detects a user input. It is preferable to provide an interface that allows the user to input the type of screen, model number, or material of the wall. For example, the user may be allowed to select whether it is a screen or a wall, or the material of the wall. Since the change in sound pressure frequency characteristic due to the material of the reflecting surface can be specified in advance, for example, if a correction value EQP according to the material is stored, the correction value EQP can be obtained from the type and material determination results.

[0061] In the processing example of FIG. 11, the adjustment control unit 23 executes both the delay time adjustment processing from step S102 to step S105 and the sound pressure frequency characteristic adjustment processing from step S106 to step S108, but it may also be configured to execute only one of them. 10 does not necessarily have to include the adjustment control unit 23 and the detection unit 24. That is, an audio output device 90 in which the calibration process as shown in FIG.

[0062] Examples of narrow-directivity speakers that can be used as the high-frequency speaker 3 include a phase interference type narrow-directivity speaker, a parabolic type narrow-directivity speaker, and an ultrasonic type narrow-directivity speaker.

[0063] Figure 12 shows a phase interference type narrow directivity speaker. This is called a beam tweeter, and is composed of a top 40, a pipe 41, a neck 42, and a driver 43. By arranging a pipe 41 with openings at a constant pitch in the sound radiating part of the tweeter, the horizontal sound pressure radiated from the openings becomes an out-of-phase component, reducing the horizontal energy. This gives it a narrow directivity with radiation in the front direction. With this phase interference type narrow directivity speaker, good narrow directivity can be obtained in the high range, for example from 5KHz or 7KHz.

[0064] Fig. 13 shows a parabolic narrow directivity speaker. This is a structure in which a speaker 45 is placed at the parabolic focus of a concave reflecting surface 44 that has a parabolic paraboloid of revolution. When sound is emitted from the speaker 45, the sound waves reflected by the concave reflecting surface 44 become parallel waves, resulting in narrow directivity. For example, good narrow directivity can be obtained in the 5KHz and 10KHz bands.

[0065] Figure 14 shows an ultrasonic narrow-directivity speaker. This uses ultrasonic waves outside the audible band, such as 40KHz, as a carrier, and uses the original sound (high-frequency sound signal SH) to AM-modulate it to obtain narrow directivity.

[0066] For example, by using a narrow directivity speaker as the high-frequency speaker 3 as in the above example, the high-frequency sound 201 can be appropriately reflected by the image display surface 111 .

[0067] <2. Second embodiment: short focus projector> FIG. 15 shows an example in which a short focus projector 50 is used as the second embodiment. Short throw projector 50 may be placed, for example, close to screen 150 as shown. In this case as well, the delayed low-mid range sound 203 reaches the viewer 120 directly, while the high range sound 201 is reflected by the video display surface 111 and reaches the viewer 120 as reflected high range sound 202 .

[0068] An example of speaker arrangement in a short focus projector 50 is shown in FIG. 16A is a perspective view seen from the projection screen side, FIG. 16B is a perspective view seen from the viewer side, and FIG. 16C is a view seen in the planar direction.

[0069] A projection unit 2 is provided on the top surface of the housing of the short focus projector 50, and this projects an image onto a screen 150 or the like. The low-midrange speakers 4 are provided on the viewer-facing surface of the housing. In this example, a three-channel configuration is used, and L-channel, R-channel, and C-channel speakers are arranged as the low-midrange speakers 4.

[0070] The high-frequency speaker 3 is disposed on the projection surface side of the housing, for example, facing the image projection direction of the projection unit 2. In this example, a three-channel configuration is used, and L-channel, R-channel, and C-channel speakers are disposed as the high-frequency speaker 3. High-frequency sound 201 outputted from such a high-frequency speaker 3 is emitted toward the image display surface 111. Note that the high-frequency speaker 3 may be provided on the top surface of the housing.

[0071] The L-channel and R-channel high-frequency speakers 3 are positioned so that the high-frequency audio 201 is directed toward the image display surface 111 with each having a radiation angle AG1 as described in Figure 9, and the C-channel high-frequency speaker 3 is positioned so that the high-frequency audio 201 is directed toward the center of the image display surface 111.

[0072] The configuration of the audio output device 90 built into the short focus projector 50 is as described with reference to FIG. As a result, in the case of the short focus projector 50 as well, it is possible to provide the viewer 120 with a state in which the playback positions of the video and audio are aligned, similar to the projector 1 of the first embodiment.

[0073] <3. Third embodiment: Bar-shaped speaker> As a third embodiment, for example, a bar-shaped speaker 60 called a sound bar will be given as an example. Fig. 17 shows an example in which a separate bar-shaped speaker 60 is arranged near a short focus projector 50. An image 110 is projected onto an image display surface 111 by the short focus projector 50, and sound is output by the bar-shaped speaker 60.

[0074] In this case, the bar-shaped speaker 60 incorporates an audio output device 90 as shown in FIG. 10, which outputs delayed low-mid range audio 203 so that it reaches the viewer 120 directly, and the high range audio 201 is reflected by the video display surface 111 and reaches the viewer 120 as reflected high range audio 202.

[0075] An example of speaker arrangement in the bar-shaped speaker 60 is shown in FIG. FIG. 18A is a perspective view seen from the viewer side, and FIG. 18B is a perspective view seen from the projection screen side.

[0076] The mid-low range speaker 4 is provided on the viewer side surface of the housing of the bar-shaped speaker 60. In this example, a three-channel configuration is used, and L channel, R channel, and C channel speakers are arranged as the mid-low range speaker 4.

[0077] The high-frequency speaker 3 is disposed on the projection surface side of the housing, facing, for example, in the direction of image projection by the short focus projector 50. In this example, a three-channel configuration is used, and L-channel, R-channel, and C-channel speakers are disposed as the high-frequency speaker 3. High-frequency sound 201 outputted from such a high-frequency speaker 3 is emitted toward the image display surface 111. Note that the high-frequency speaker 3 may be provided on the top surface of the housing.

[0078] The L-channel and R-channel high-frequency speakers 3 are positioned so that the high-frequency audio 201 is directed toward the image display surface 111 with each having a radiation angle AG1 as described in Figure 9, and the C-channel high-frequency speaker 3 is positioned so that the high-frequency audio 201 is directed toward the center of the image display surface 111. The bar-shaped speaker 60 incorporates an audio output device 90 having the configuration shown in FIG.

[0079] In this way, in the bar-shaped speaker 60 separate from the short focus projector 50, the high-frequency sound 201 is reflected on the image display surface 111, and the mid-low-frequency sound 203 is delayed so that it reaches the viewer 120 directly, thereby providing the viewer with a state in which the playback positions of the image and the sound match, even if the short focus projector 50 is a device that does not include the audio output device 90 of the present disclosure. Also, not limited to the short focus projector 50, but also when using a portable type projector 1 or other general projectors, the bar-shaped speaker 60 can provide a state in which the playback positions of the image and the sound match. Although the bar-shaped speaker 60 has been given as an example, the shape is not limited to a bar shape, and the present technology can be applied to various types of speaker devices separate from the projector.

[0080] <4. Fourth embodiment: Ceiling-mounted projector> As the fourth embodiment, an example of a ceiling-mounted projector 70 is shown in FIGS. 19 shows an example of the appearance of a ceiling-mounted projector 70, in which a projection unit 2 is provided on the peripheral portion of a cylindrical shape. In addition, high-frequency speakers 3, 3 for the L channel and R channel are provided on the left and right of the projection unit 2. Low-midrange speakers 4, 4 for the L and R channels are provided on the bottom surface of the housing.

[0081] An example of how this ceiling-mounted projector 70 is used is shown in FIG. The ceiling-mounted projector 70 projects an image 110 from the projection unit 2 onto a screen 150 or the like. High-frequency sound 201 from the high-frequency speakers 3, 3 is output toward the image display surface 111, and reflected high-frequency sound 202 reaches the viewer 120. Further, the mid-low frequency sound 203 is outputted directly from near the ceiling into the room in which the viewer 120 is present.

[0082] By incorporating an audio output device 90 configured as shown in FIG. 10 in this ceiling-mounted projector 70, it is possible to provide the viewer 120 with a state in which the playback positions of the video and audio are aligned.

[0083] <5. Summary and examples of modifications> According to the above embodiment, the following effects can be obtained. The audio output device 90 of the embodiment includes a high-frequency speaker 3 (first speaker) configured as a directional speaker arranged facing the video display surface 111, a mid-low frequency speaker 4 (second speaker) with a directivity wider than that of the high-frequency speaker 3, and an audio signal processor 21. The audio signal processor 21 extracts signal components on the high frequency band side of the audio signal SI output together with the video 110 to be displayed on the video display surface 111, and sets the signal components as a high frequency audio signal SH (first audio signal) to be supplied to the high frequency speaker 3. The audio signal processor 21 also extracts signal components including a lower frequency band side than the first audio signal from the audio signal SI output together with the video to be displayed on the video display surface 111, performs delay processing, and sets the signal components as a mid-low frequency audio signal SML (second audio signal) to be supplied to the mid-low frequency speaker 4. With this configuration, of the sounds accompanying the video, reflected high-frequency sound 202 that is output from high-frequency speaker 3 and reflected by video display screen 111 reaches the viewer, and mid-low-frequency sound 203 reaches the viewer with a delay. Therefore, viewer 120 perceives reflected high-frequency sound 202 that is reflected by video display screen 111 before mid-low-frequency sound 203, and the sound image is localized on video display screen 111 due to the Haas effect. This makes it possible to match the playback positions of the video and audio perceived by the viewer, providing a more comfortable and realistic viewing environment.

[0084] In the embodiment, the first audio signal is a high-frequency audio signal SH, and the second audio signal is a low-mid frequency audio signal SML. However, it is not necessary for the high-frequency audio signal SH and the low-mid frequency audio signal SML to include the entire audible band. All that is required is that a certain higher frequency band be the first audio signal, and a signal including a lower frequency band than the first audio signal be the second audio signal. Furthermore, in the case where the high-frequency side is, for example, an audio signal component in a specific band of approximately 3 KHz to 10 KHz as the first audio signal, and an audio signal component including all or part of the low-mid range below 3 KHz as the second audio signal, it is also possible to include a band above 10 KHz in the second audio signal. That is, if the first audio signal, which includes at least the frequency band to which humans are sensitive, is made to reach the viewer 120 earlier than the second audio signal due to the Haas effect, this is suitable as audio synchronized with the video.

[0085] In the embodiment, the high-frequency sound 201 is reflected once by the video display surface 111 and reaches the viewer 120 as the reflected high-frequency sound 202. In other words, the sound emission direction of the high-frequency speaker 3 is set so that it reaches the viewer 120 with one reflection by the video display surface 111. If the sound were to reach the viewer 120 after being reflected by the video display surface 111 and then reflected by the ceiling or a wall, the viewer 120 would not be able to localize the sound image on the video display surface 111. Therefore, in order to make the viewer perceive the playback positions of the video and the audio as being the same, the arrangement (sound emission direction) of the high-frequency speaker 3 is set so that the reflected high-frequency sound 202 reflected by the video display surface 111 reaches the viewer 120 directly. Of course, since the position of the viewer 120 cannot be uniquely identified, it is sufficient to set the reflected high-frequency sound 202 to travel approximately in front of the video display surface 111. In addition, the reflected high-frequency sound 202 reaches the viewer 120 directly, which means that the sound reaches the viewer 120 in the shortest possible straight line from the image display surface 111, and this is advantageous in terms of setting the delay time for the Haas effect appropriately.

[0086] In the first, second and fourth embodiments, the audio output device 90 is configured to include the projection unit 2 that projects an image onto the image display screen 111. In other words, the audio output device 90 of the present technology is mounted on a projector. For example, the above-mentioned projector 1, the short focus projector 50, the ceiling-mounted projector 70, and the like are conceivable as projectors with built-in speakers. With such projectors, even if they are placed away from the image display surface 111, the playback positions of the image and the audio can be aligned, improving the marketability of the projector.

[0087] In the first, second and fourth embodiments, the high-frequency speaker 3 is arranged so as to output audio in the direction in which the projection unit 2 projects an image. As a result, when projecting an image using a projector, sound from the high-frequency speaker 3, which is a narrow-directivity speaker, is naturally output toward the image display surface 111. Therefore, if the user places the projector in any projection direction, an environment can be obtained in which the playback positions of the image and sound according to this technology naturally match without the user being aware of it.

[0088] In the embodiment, an example has been given in which the mid-low range speaker 4 is an omnidirectional speaker. By outputting the mid-low range sound 203 from the non-directional mid-low range speaker 4, the mid-low range sound 203 can be easily heard regardless of the user's position. For example, it is possible to avoid restricting the user's preferred position around the projector 1, etc.

[0089] In the embodiment, multiple channel speakers including an L channel and an R channel are provided as the high-frequency speakers 3, and the L channel high-frequency speaker 3 is fixedly positioned facing the left region of the image display surface 111, and the R channel high-frequency speaker 3 is fixedly positioned facing the right region of the image display surface 111 (see Figures 9A and 9B). By distributing the sound output directions of the L-channel and R-channel high-frequency speakers 3 to the left and right at a specified radiation angle AG1, if the distance from the projector 1 to the screen 150 increases, the distance between the positions on the image display surface 111 at which the L-channel sound and the R-channel sound arrive will increase. In other words, the arrival positions of the L- and R-channel sounds will naturally change as the size of the image 110 changes. As a result, if the L- and R-channel high-frequency speakers 3 are disposed at an appropriate radiation angle AG1, there is no need to adjust the arrangement direction of the high-frequency speakers 3.

[0090] In the embodiment, an example has been given in which audio output device 90 includes adjustment control unit 23 that sets the delay time of delay processing by audio signal processing unit 21 based on detection information regarding the distance from video display screen 111. The detection information regarding distance is assumed to be various information such as the distance itself, a time difference caused by the distance, and a value that changes depending on the distance. In order to localize a sound image on the video 110 by the Haas effect while allowing the viewer 120 to experience a natural playback sound, it is desirable to appropriately adjust the delay time of the reflected high-frequency sound 202 and the mid-low-frequency sound 203 that reach the viewer 120. Therefore, it is preferable to finely adjust the delay time given to the mid-low-frequency sound 203 according to the distance between the projector 1 and the screen 150. By adjusting the delay time according to the distance between the projector 1 and the screen 150 through the calibration process of the adjustment control unit 23, an appropriate delay time can be set even if the user places the projector 1 in an arbitrary position. This is particularly suitable for a portable projector. The detection information includes, for example, detection information of an operation when a user inputs a distance, distance information from a distance measuring sensor, focus information, and an audio signal detected by a microphone.

[0091] In the embodiment, an example has been given in which adjustment control unit 23 sets the delay time based on detection information from a distance measurement sensor. For example, the detection unit 24 in Fig. 10 may be provided with a distance measuring sensor such as a ToF sensor, and may measure the distance to the screen 150. This allows the distance between the projector 1 and the screen 150 to be detected, and an appropriate delay time for obtaining the Haas effect to be set.

[0092] In the embodiment, an example has been given in which the adjustment control unit 23 sets the delay time based on the focus information detected by the focus information detection unit. For example, a focus information detection unit is provided as the detection unit 24 in Fig. 10 to obtain focus information. The focus information here is, for example, defocus information and distance measurement information. Since the distance to the screen 150 can be obtained from the focus information, it is possible to set an appropriate delay time for obtaining the Haas effect. In addition, by using the focus information from the focus information detection unit mounted on the projector 1, there is also an advantage that no additional configuration is required, especially for setting the delay time.

[0093] In the embodiment, an example has been described in which the adjustment control unit 23 sets the delay time based on detection information of the time difference between the high-frequency audio signal SH and the audio signal obtained by outputting the high-frequency audio signal SH from the high-frequency speaker 3 and collecting it with a microphone. For example, by providing a microphone as the detector 24 in Fig. 10 and obtaining the time difference between the high-frequency audio signal SH output from the high-frequency speaker 3 and the audio signal collected by the microphone, it is possible to determine the delay time according to the distance between the projector 1 and the screen 150. This makes it possible to set an appropriate delay time for obtaining the Haas effect.

[0094] In the embodiment, the audio signal processing unit 21 is capable of adjusting the sound pressure frequency characteristic of the high-frequency audio signal SH by the equalizer 34. The audio signal processing unit 21 includes an adjustment control unit 23 that sets the sound pressure frequency characteristic of the adjustment process by the audio signal processing unit 21. Since the high-frequency sound 201 is reflected by the image display surface 111 such as the screen 150, attenuation and changes in frequency characteristics may occur in the reflected high-frequency sound 202 depending on the material and type of the image display surface 111. Therefore, by correcting the sound pressure frequency characteristics of the high-frequency sound signal SH in advance, assuming changes in the sound pressure frequency characteristics of the reflected high-frequency sound 202, the reflected high-frequency sound 202 that reaches the viewer 120 can have the original sound pressure frequency characteristics. In particular, in the case of a portable projector, the screen 150 is made of a wide variety of materials. By being able to variably adjust the sound pressure frequency characteristics of the high-frequency sound signal SH, it can be adapted to various screens 150.

[0095] In the embodiment, an example has been given in which adjustment control section 23 determines the type of video display screen 111 based on an image captured by the imaging section, and sets the sound pressure frequency characteristic based on the determination result. For example, an imaging unit may be provided as the detector 24 in Fig. 10 so as to acquire an image of the video display surface 111. By analyzing the image and determining the material of the screen 150 or the like that forms the video display surface 111, it is possible to estimate the change in the sound pressure frequency characteristic due to reflection. Therefore, the sound pressure frequency characteristic to be corrected can be calculated and the correction value EQP by the equalizer 34 of the audio signal processor 21 can be set. This makes it possible to prevent or reduce the change in the sound pressure frequency characteristic of the reflected high-frequency sound 202 that reaches the viewer 120 due to the influence of the video display surface 111.

[0096] In the embodiment, an example has been given in which the adjustment control unit 23 sets the sound pressure frequency characteristics by comparing the sound pressure frequency characteristics of the high-frequency audio signal SH with an audio signal obtained by outputting the high-frequency audio signal SH from the high-frequency speaker 3 and collecting the audio with a microphone. For example, by providing a microphone as the detector 24 in Fig. 10 to obtain an audio signal of the reflected high-frequency sound 202 and comparing this with the high-frequency sound signal SH before output (audio signal at the output stage of the HPF 32), it is possible to determine a change in the sound pressure frequency characteristic due to reflection. Therefore, it is possible to calculate the sound pressure frequency characteristic to be corrected and set the correction value EQP by the equalizer 34 of the audio signal processor 21. This makes it possible to prevent or reduce changes in the sound pressure frequency characteristic of the reflected high-frequency sound 202 that reaches the viewer 120 due to the influence of the video display surface 111.

[0097] In the embodiment, an example has been given in which the adjustment control unit 23 sets the sound pressure frequency characteristic based on operation information input from the operation input unit. For example, an operation input unit may be provided as the detection unit 24 in Fig. 10, allowing the user to input the type of the image display surface 111. This allows the change in the sound pressure frequency characteristic due to reflection to be estimated, so that the sound pressure frequency characteristic to be corrected can be calculated and a correction value EQP for the equalizer 34 of the audio signal processing unit 21 can be set. This makes it possible to prevent or reduce changes in the sound pressure frequency characteristic of the reflected high-frequency sound 202 reaching the viewer 120 due to the influence of the image display surface 111.

[0098] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0099] The present technology can also be configured as follows. (1) a first speaker that is a directional speaker arranged facing the image display surface; A second speaker having a wider directivity than at least the first speaker; an audio signal processing unit that extracts a signal component on the high frequency band side of an audio signal output together with the video to be displayed on the video display screen, and generates a first audio signal to be supplied to the first speaker, and extracts a signal component including a lower frequency band side than the first audio signal from the audio signal output together with the video to be displayed on the video display screen, performs delay processing, and generates a second audio signal to be supplied to the second speaker. Audio output device. (2) a projection unit that projects an image onto the image display surface; The audio output device according to (1) above. (3) The first speaker is disposed to output sound in a direction in which the image is projected by the projection unit. The audio output device according to (2) above. (4) The second speaker is an omnidirectional speaker. An audio output device according to any one of (1) to (3) above. (5) A multi-channel speaker including a left channel and a right channel is provided as the first speaker, the first speaker of the left channel is fixedly disposed facing a left region of the image display surface, The first speaker of the right channel is fixedly disposed facing the right region of the image display surface. An audio output device according to any one of (1) to (4) above. (6) an adjustment control unit that sets the delay time of the delay processing by the audio signal processing unit based on detection information regarding the distance from the video display surface; An audio output device according to any one of (1) to (5) above. (7) The adjustment control unit sets the delay time based on detection information from a distance measuring sensor. The audio output device according to (6) above. (8) The adjustment control unit sets the delay time based on detection information of focus information used for focus control of a projected image by a projection unit that projects an image onto the image display screen. The audio output device according to (6) above. (9) The adjustment control unit sets the delay time based on detection information of a time difference between the first audio signal and an audio signal collected by a microphone regarding the audio output from the first speaker of the first audio signal. The audio output device according to (6) above. (10) The audio signal processing unit is capable of adjusting a sound pressure frequency characteristic of the first audio signal, an adjustment control unit that sets a sound pressure frequency characteristic of the adjustment process by the audio signal processing unit; An audio output device according to any one of (1) to (9) above. (11) The adjustment control unit determines a type of the video display screen based on an image captured by an imaging unit that captures an image of the video display screen side, and sets a sound pressure frequency characteristic of the adjustment process based on a determination result. The audio output device according to (10) above. (12) The adjustment control unit compares a sound pressure frequency characteristic between the first audio signal and an audio signal obtained by outputting the first audio signal from the first speaker and collecting the sound by a microphone, and sets a sound pressure frequency characteristic for the adjustment process. The audio output device according to (10) above. (13) The adjustment control unit sets a sound pressure frequency characteristic of the adjustment process based on operation information input from an operation input unit that inputs a user operation. The audio output device according to (10) above. (14) A signal component on the high frequency band side of an audio signal to be output together with an image to be displayed on a video display screen is extracted to produce a first audio signal, and the first audio signal is supplied to a first speaker, which is a directional speaker arranged facing the video display screen, to output the first audio signal as audio; A signal component including a lower frequency band side than the first audio signal is extracted from the audio signal to be output together with the image to be displayed on the image display screen, and a delay process is performed to obtain a second audio signal. The second audio signal is supplied to a second speaker having a directionality at least wider than that of the first speaker, and output as audio. Audio output method. [Explanation of symbols]

[0100] 1 Projector 2 Projection section 3 High-frequency speakers 4 mid-range speakers 6 sound hole 20 Audio Sources 21 Audio signal processing section 22 Amplifier 23 Adjustment control section 24 Detection unit 31 LPF 32 HPF 33 Delay section 34 Equalizer 50 Short-focus projector 60 Bar Speaker 70 Ceiling-mounted projector 90 Audio output device 201 High-frequency voice 202 Reflected High-Frequency Voice 203 Mid-low range audio

Claims

1. a first speaker that is a directional speaker arranged facing the image display surface; A second speaker having a wider directivity than at least the first speaker; an audio signal processing unit that extracts a signal component on a high frequency band side of an audio signal output together with the image to be displayed on the video display screen, and generates a first audio signal to be supplied to the first speaker, and extracts a signal component including a lower frequency band side than the first audio signal of the audio signal output together with the image to be displayed on the video display screen, performs delay processing, and generates a second audio signal to be supplied to the second speaker. Audio output device.

2. a projection unit that projects an image onto the image display surface; The audio output device according to claim 1 .

3. The first speaker is disposed to output sound in a direction in which an image is projected by the projection unit. The audio output device according to claim 2 .

4. The second speaker is an omnidirectional speaker. The audio output device according to claim 1 .

5. A multi-channel speaker including a left channel and a right channel is provided as the first speaker, the first speaker of the left channel is fixedly disposed facing a left region of the image display surface, The first speaker of the right channel is fixedly disposed facing the right region of the image display surface. The audio output device according to claim 1 .

6. an adjustment control unit that sets the delay time of the delay processing by the audio signal processing unit based on detection information regarding the distance from the image display surface; The audio output device according to claim 1 .

7. The adjustment control unit sets the delay time based on detection information from a distance measuring sensor. The audio output device according to claim 6.

8. The adjustment control unit sets the delay time based on detection information of focus information used for focus control of a projected image by a projection unit that projects an image onto the image display screen. The audio output device according to claim 6.

9. The adjustment control unit sets the delay time based on detection information of a time difference between the first audio signal and an audio signal collected by a microphone regarding the audio output from the first speaker of the first audio signal. The audio output device according to claim 6.

10. The audio signal processing unit is capable of adjusting a sound pressure frequency characteristic of the first audio signal, an adjustment control unit that sets a sound pressure frequency characteristic of the adjustment process by the audio signal processing unit; The audio output device according to claim 1 .

11. The adjustment control unit determines a type of the video display screen based on an image captured by an imaging unit that captures an image of the video display screen side, and sets a sound pressure frequency characteristic of the adjustment process based on a determination result. The audio output device according to claim 10.

12. The adjustment control unit compares sound pressure frequency characteristics between the first audio signal and an audio signal obtained by outputting the first audio signal from the first speaker and collecting the sound with a microphone, and sets the sound pressure frequency characteristics of the adjustment process. The audio output device according to claim 10.

13. The adjustment control unit sets a sound pressure frequency characteristic of the adjustment process based on operation information input from an operation input unit that inputs a user operation. The audio output device according to claim 10.

14. A signal component on the high frequency band side of an audio signal output together with an image to be displayed on the image display screen is extracted to produce a first audio signal, and the first audio signal is supplied to a first speaker, which is a directional speaker arranged facing the image display screen, to output the first audio signal as audio; A signal component including a lower frequency band side than the first audio signal is extracted from the audio signal to be output together with the image to be displayed on the image display screen, and a delay process is performed to obtain a second audio signal. The second audio signal is supplied to a second speaker having a directionality at least wider than that of the first speaker, and the second audio signal is output as an audio signal. Audio output method.

Images