Sound output device

Abstract

Sound output device (101), comprising a first loudspeaker (1, 50) and a second loudspeaker (2, 51), each emitting tones, and a switch (37) to switch the second loudspeaker (2, 51) so that it functions as a sound output element that converts a sound signal into a tone, or as a sound receiving element that converts a tone into a sound signal, wherein the first loudspeaker (1, 50) and the second loudspeaker (2, 51) form a coaxial loudspeaker, and the sound output device (101) further comprises: a switch control section (41) which, based on a tone signal of a tone emitted by the second loudspeaker (2, 51), performs a control by which the switch (37) switches the second loudspeaker (2, 51) in such a way that it acts as a tone receiver.

Description

Technical area

[0001] The present disclosure relates to a sound output device. Background technology

[0002] Patent Document 1 discloses a vehicle proximity notification device comprising a first speaker and a second speaker, each of which emits a warning sound. The vehicle proximity notification device further includes a switch for switching the first speaker or the second speaker between functioning as a sound output element that converts an electrical signal into a sound and functioning as a sound pickup element that converts a sound into an electrical signal.

[0003] In the vehicle proximity detection device in question, a sound emitted by one speaker from either the first speaker or the second speaker is picked up by the other speaker. In the vehicle proximity detection device in question, a defect assessment is performed to determine whether one speaker is defective or not by comparing a picked-up sound signal obtained by picking up the other speaker with a reference signal. JP 2005 - 277 514 A describes a hands-free device in which a loudspeaker with hands-free function provided in a vehicle-mounted audio device is also used as a hands-free microphone. JP 2002 - 209 293 A describes a structure of a loudspeaker unit capable of directing the sound emitted by a loudspeaker in advance in a desired direction. US 5,652,566 A relates to a redundant alarm system with a first and second audible alarm, each having a transducer for generating the audible alarm signals. An acoustic sensor is used to monitor whether the first alarm is transmitting an audible alarm signal. If a controller does not receive a feedback signal from the acoustic sensor, the controller sends an enable signal to the second alarm to output the second alarm signal. US 2009 / 0 274 ​​312 A1 describes an entertainment system consisting of multiple components, where it is useful if one component can confirm that the other components are correctly connected. A processor causes an electroacoustic transducer system or individual channels to generate a test tone at listening volume. A microphone records the test sound and forwards it to the processor. The processor receives the measured sound from the microphone and calculates a response characteristic, e.g., an acoustic transfer function, of the one or more electroacoustic transducers in the channel being tested in combination with the listening volume. US 2005 / 0 253 713 A1 relates to an audio device with a transducer. The transducer has a sound output mode in which the transducer functions as a sound output device for converting a sound signal into a sound output, and a sound pickup mode in which the transducer functions as a sound pickup device for converting a sound signal into a sound output. The audio device also includes a controller that switches the transducer to the sound output mode or the sound pickup mode, an analysis section that analyzes the sound output generated by the transducer, which is switched to the sound pickup mode by the controller, and an alarm section that generates an alarm signal based on an analysis result. COLLOMS, Martin; DARLINGTON, Paul: Dual concentric drivers. In: High performance loudspeakers: Optimising high fidelity loudspeaker systems. 7th ed. Hoboken, NJ. Wiley, 2018. pp. 331–333. - ISBN 978-1-118-41353-1 concerns the optimization of high fidelity (hi-fi) loudspeaker systems. Prior art documentsPatent documents

[0004] Patent Document 1: Int. Disclosure No. WO 2017 / 085 925 A1 Overview of the inventionProblem to be solved by the invention

[0005] In a sound output device such as this vehicle proximity notification device, the first speaker and the second speaker are provided separately, so the relative distance and angle between the first speaker and the second speaker vary slightly. Therefore, there is a problem of deterioration of a captured sound signal picked up by one speaker from either the first speaker or the second speaker, and a deterioration in the accuracy of the defect judgment as to whether the other speaker is defective.

[0006] The present disclosure has been made to solve the above problems and intends to provide a technology for improving the precision of defect judgment. Means of solving the task

[0007] The present invention is defined in the appended main claim. Further preferred embodiments are described in the appended subclaims.

[0008] The sound output device according to the present disclosure includes a first speaker and a second speaker, each outputting a sound, and a switch for switching the second speaker to function as a sound output element that converts a sound signal into a sound or to function as a sound pickup element that converts a sound into a sound signal, wherein the first speaker and the second speaker constitute a coaxial speaker. Effects of the invention

[0009] According to the present disclosure, the precision of defect assessment can be improved. Brief explanation of the figures [ Fig. 1] Fig. 1 is a schematic view showing a speaker unit according to a first embodiment. [ Fig. 2] Fig. 2 is a block diagram showing the structure of a sound output device according to the first embodiment. [ Fig. 3] Fig. 3 is a flowchart showing an interruption process by the sound output device according to the first embodiment. [ Fig. 4] Fig. 4 is a flowchart showing a sound output method by the sound output device according to the first embodiment. [ Fig. 5] Fig. 5 is a cross-sectional view showing a speaker unit according to a first modification of the first embodiment. [ Fig. 6] Fig. 6 is a cross-sectional view showing a speaker unit according to a second modification of the first embodiment. [ Fig. 7] Fig. 7A is a block diagram showing a hardware configuration for realizing the functions of the control section of the sound output device according to the first embodiment. Fig. 7B is a block diagram showing the hardware structure for executing software by which the functions of the control section of the sound output device according to the first embodiment are realized. Forms for carrying out the invention

[0010] In order to explain the present disclosure in more detail, forms for carrying out the present disclosure are explained below with reference to the accompanying drawings. First embodiment

[0011] Fig. 1 is a schematic view showing a speaker unit 100 according to the first embodiment. As shown in Fig. As shown in Figure 1, the speaker unit 100 is a coaxial speaker. A coaxial speaker here refers to a coaxial speaker that includes a first speaker and a second speaker that are attached to each other.

[0012] More specifically, in the coaxial speaker, for example, the structural center axis of the first speaker and the structural center axis of the second speaker coincide. For example, the first speaker has a rotationally symmetric structure with respect to the center axis. Furthermore, for example, the second speaker has a rotationally symmetric structure with respect to the center axis. In other words, for example, in the coaxial speaker, the sound output direction of the first speaker and the sound output direction of the second speaker coincide. Further, for example, a sound output section of the second speaker is arranged at the center of a sound output area in the sound output section of the first speaker. In this case, the sound output area of ​​the sound output section of the second speaker is smaller than the sound output area of ​​the sound output section of the first speaker.

[0013] As in Fig. As shown in Figure 1, the speaker unit 100 according to the first embodiment includes a woofer 1 as the first speaker and a tweeter 2 as the second speaker. The woofer 1 and the tweeter 2 form a coaxial speaker.

[0014] More specifically, in the first embodiment, the woofer 1 consists of a woofer input terminal 10, a magnetic circuit 11, a woofer cone 12 as the cone for the first speaker, and a frame section 13. The tweeter 2 consists of a tweeter input terminal 20, the magnetic circuit 11, and a tweeter cone 21 as the cone for the second speaker. The magnetic circuit 11 is shared by the woofer 1 and the tweeter 2.

[0015] The tweeter cone 21 of the tweeter 2 and the woofer cone 12 of the woofer 1 are fixed to each other. Furthermore, in the first embodiment, the structural center axis of the tweeter cone 21 of the tweeter 2 and the structural center axis of the woofer cone 12 of the woofer 1 coincide. In other words, the sound output direction of the tweeter 2 and the sound output direction of the woofer 1 coincide. Furthermore, the tweeter cone 21 of the tweeter 2 is positioned at the center of a sound output surface A of the woofer cone 12 of the woofer 1. Furthermore, the surface (not shown) opposite the sound output surface A of the woofer cone 12 of the woofer 1 is covered by the frame section 13.

[0016] The woofer input terminal 10 receives audio signals for the woofer. The magnetic circuit 11 vibrates the woofer cone 12 based on the audio signal received by the woofer input terminal 10. The woofer cone 12 emits sound through vibration. The frame section 13 supports the vibrating woofer cone 12.

[0017] The tweeter input terminal 20 receives audio signals for the tweeter. The magnetic circuit 11 vibrates the tweeter cone 21 based on the audio signal received by the tweeter input terminal 20. The tweeter cone 21 emits sounds through the vibration.

[0018] Fig. Fig. 2 is a block diagram showing the structure of a sound output device 101 according to the first embodiment. Fig. 2, the sound output device 101 comprises a sound source 30, a first correction filter 31, a second correction filter 32, a first amplifier 33, a second amplifier 34, a first band-band filter 35, a second band-band filter 36, the woofer 1 as the first loudspeaker, the tweeter 2 as the second loudspeaker, a switch 37, a third amplifier 38 and a control section 39. In Fig. 2, the woofer 1 and the tweeter 2 are shown separately, however, as stated above, the woofer 1 and the tweeter 2 are considered to be constructed as a coaxial loudspeaker.

[0019] The sound source 30 generates a sound signal. More specifically, in the first embodiment, the sound signal generated by the sound source 30 is a sound signal of a warning sound. The sound source 30 outputs the generated sound signal to the first correction filter 31, the second correction filter 32, and the control section 39, respectively. In the first embodiment, an explanation will be given regarding a configuration in which the sound signal generated by the sound source 30 is a sound signal of a warning sound, but the sound signal generated by the sound source 30 may also be a sound signal other than a sound signal of a warning sound. For example, the sound signal generated by the sound source 30 may be a sound signal of music, etc.

[0020] The first correction filter 31 corrects a gain per frequency in the audio signal of a sound output from the woofer 1 based on the control of the control section 39. Specifically, in the first embodiment, the first correction filter 31 corrects a gain per frequency in the audio signal generated by the audio source 30 based on the control of the control section 39. The structure of the first correction filter 31 will be explained in more detail later. The first correction filter 31 outputs the corrected audio signal to the first amplifier 33.

[0021] The second correction filter 32 corrects a gain per frequency in the audio signal of a sound output from the tweeter 2 based on the control of the control section 39. Specifically, in the first embodiment, the second correction filter 32 corrects a gain per frequency in the audio signal generated by the audio source 30 based on the control of the control section 39. The structure of the second correction filter 31 will be explained in more detail later. The second correction filter 32 outputs the corrected audio signal to the second amplifier 34.

[0022] The first amplifier 33 amplifies the audio signal corrected by the first correction filter 31. The first amplifier 33 outputs the amplified audio signal to the first band-band filter 35.

[0023] The second amplifier 34 amplifies the audio signal corrected by the second correction filter 32. The second amplifier 34 outputs the amplified audio signal to the second band-band filter 36.

[0024] The first band-band filter 35 filters the audio signal amplified by the first amplifier 33. Specifically, in the first embodiment, the first band-band filter 35 attenuates a high-pitched audio signal among the audio signals amplified by the first amplifier 33 with a low-pitched audio signal among the audio signals amplified by the first amplifier 33. The first band-band filter 35 outputs the filtered audio signal to the woofer 1. This audio signal is a woofer audio signal acquired through the woofer input terminal 10.

[0025] The second band-band filter 36 filters the audio signal amplified by the second amplifier 34. Specifically, in the first embodiment, the second band-band filter 36 attenuates a low-pitched audio signal among the audio signals amplified by the second amplifier 34 with a high-pitched audio signal among the audio signals amplified by the second amplifier 34. The second band-band filter 36 outputs the filtered audio signal to the tweeter 2. This audio signal is a tweeter audio signal acquired through the tweeter input terminal 20.

[0026] As described above, the woofer 1 outputs sounds. Specifically, in the first embodiment, the woofer 1 converts the sound signal filtered by the first band-band filter 35 into a sound and outputs it. More specifically, in the first embodiment, the woofer 1 converts the sound signal filtered by the first band-band filter 35 into a warning sound and outputs it.

[0027] In the first embodiment, the explanation will be given with respect to a structure in which the woofer 1 is used as the first speaker, but the first speaker may be a speaker other than the woofer 1. For example, the first speaker may be a squaker, a subwoofer, a tweeter, etc.

[0028] As described above, tweeter 2 outputs tones. Specifically, in the first embodiment, tweeter 2 converts the sound signal filtered by second band-band filter 36 into a tone and outputs it. More specifically, in the first embodiment, tweeter 2 converts the sound signal filtered by second band-band filter 36 into a warning tone and outputs it.

[0029] By capturing a sound emitted by the woofer 1, the tweeter 2 converts the sound into a captured audio signal. More specifically, in the first embodiment, by capturing a warning sound emitted by the woofer 1, the tweeter 2 converts the warning sound into a captured audio signal. Whether the tweeter 2 outputs a sound or captures a sound is controlled by the switch 37 described below.

[0030] In the first embodiment, the explanation will be given with respect to a structure in which the tweeter 2 is used as the second speaker, but the second speaker may be a speaker other than the tweeter 2. For example, the second speaker may be a squaker, a woofer, or a subwoofer, etc.

[0031] The switch 37 switches the tweeter 2 as the second loudspeaker to function as a sound output element that converts a sound signal into a sound, or to function as a sound pickup element that converts a sound into a sound signal.

[0032] That is, when the switch 37 is switched, by which the tweeter 2 functions as a sound output element, the tweeter 2 converts the sound signal filtered by the second band-band filter 36 into a sound and outputs it.

[0033] When switch 37 is switched, causing tweeter 2 to function as a pickup element, tweeter 2 picks up a sound emitted by woofer 1, thereby converting the sound in question into a pickup signal. Tweeter 2 outputs the converted pickup signal to the third amplifier 38 via switch 37. The third amplifier 38 amplifies the captured audio signal converted by the tweeter 2. The third amplifier 38 outputs the amplified captured audio signal to the control section 39.

[0034] The control section 39 includes a defect judgment section 40, a switch control section 41, and a correction value calculation section 42. The defect judgment section 40 judges whether the woofer 1 is defective based on a captured sound signal that the tweeter 2 has acquired by capturing a sound output from the woofer 1. More specifically, in the first embodiment, the defect judgment section 40 judges whether the woofer 1 is defective based on a captured sound signal amplified by the third amplifier 38. The defect judgment section 40 outputs the defect judgment result to the switch control section 41 and the correction value calculation section 42, respectively.

[0035] More specifically, in the first embodiment, the defect judging section 40 judges whether the woofer 1 is defective by comparing the captured sound signal in question with a sound signal generated by the sound source 30. More specifically, the defect judging section 40 calculates a gain per frequency difference between the captured sound signal in question and the sound signal generated by the sound source 30, and judges whether the woofer 1 is defective based on the calculated gain per frequency difference. In this case, the defect judging section 40 may also output the calculated gain per frequency difference to the correction value calculating section 42.

[0036] The switch control section 41 controls the switching by the switch 37, by which the tweeter 2 as a second loudspeaker functions either as a sound output element that converts a sound signal into a sound, or as a sound pickup element that converts a sound into a sound signal.

[0037] Specifically, in the first embodiment, the switch control section 41 controls the switch 37 to switch the tweeter 2 to function as a sound output element when the woofer 1 is judged to be defective by the defect judging section 40. That is, in the first embodiment, when the woofer 1 is defective, the tweeter 2 converts a sound signal filtered by the second band-band filter 36 into a sound and outputs it.

[0038] The switch control section 41 can also control, based on a sound signal output by the tweeter 2, the switch 37 switching the tweeter 2 to function as a sound pickup element. More specifically, the switch control section 41 can also control, based on a sound signal generated by the sound source 30, the switch 37 switching the tweeter 2 to function as a sound pickup element. More specifically, in this case, for example, the switch control section 41 can judge whether the gain of the sound signal generated by the sound source 30 is less than or equal to a certain threshold value, and if the gain is less than or equal to the certain threshold value, the switch 37 can switch the tweeter 2 to function as a sound pickup element.

[0039] The correction value calculation section 42 calculates, in the case where the defect judgment section 40 has judged a defect of the woofer 1, at least one of a correction value for the gain per frequency of a sound signal output by the woofer 1 and a correction value for the gain per frequency of a sound signal output by the tweeter 2. More specifically, in the first embodiment, in the case where the defect judgment section 40 has judged a defect of the woofer 1, the correction value calculation section 42 calculates at least one of a correction value per frequency by the first correction filter 31 and a correction value per frequency by the second correction filter 32.

[0040] In the first embodiment, if a correction value per frequency was calculated by the first correction filter 31 through the correction calculation section 42, the first correction filter 31 corrects the gain per frequency in the audio signal generated by the audio source 30 based on the correction value per frequency calculated by the correction value calculation section 42. In the first embodiment, if a correction value per frequency was calculated by the second correction filter 32 through the correction calculation section 42, the second correction filter 32 corrects the gain per frequency in the audio signal generated by the audio source 30 based on the correction value per frequency calculated by the correction value calculation section 42.

[0041] Regarding the calculation method of the correction value by the correction value calculation section 42, for example, the correction value calculation section 42 may also calculate at least one of a correction value per frequency by the first correction filter 31 and a correction value per frequency by the second correction filter 32 based on the above-described captured audio signal. Further, for example, the correction value calculation section 42 may calculate at least one of a correction value per frequency by the first correction filter 31 and a correction value per frequency by the second correction filter 32 based on the above-described gain of the difference per frequency calculated by the defect judgment section 40.

[0042] The operation of the sound output device 101 according to the first embodiment will be explained below with reference to the drawings. Fig. 3 is a flowchart showing an interruption process by the sound output device 101 according to the first embodiment. Fig. 4 is a flowchart showing a sound output method by the sound output device 101 according to the first embodiment. It is assumed that, before performing the following individual steps, the tweeter 2 has been switched to function as a sound pickup element by the switch 37.

[0043] As in Fig. As shown in Figure 3, the control section 39 judges whether a warning sound playback command has been acquired from an external system (not shown) (step ST1). The external system is, for example, an ECU (Electronic Control Unit), etc.

[0044] If the control section 39 judges that a warning sound playback command has been acquired (YES in step ST1), interrupt processing starts and step ST10 in Fig. 4 is executed. If the control section 39 no longer receives a warning sound playback command during the processing from step ST10, the relevant processing is interrupted.

[0045] If the control section 39 has judged that no warning sound playback command has been acquired (NO in step ST1), step ST1 is repeatedly executed until a warning sound playback command is acquired.

[0046] In step ST10, the control section 39 judges whether the woofer 1 is defective based on the immediately previous defect judgment result by the defect judgment section 40. At this time, the control section 39 may also judge whether the woofer 1 has been repaired.

[0047] If it is judged that the woofer 1 is not defective (NO in step ST10), the control section 39 controls the woofer 1 to emit a warning tone (step ST11). As a result, the tweeter 2 captures a warning tone emitted by the woofer 1, converting the warning tone into a captured audio signal. The third amplifier 38 then amplifies the captured audio signal converted by the tweeter 2. The third amplifier 38 outputs the amplified captured audio signal to the defect judgment section 40 of the control section 39.

[0048] Then, the defect judging section 40 of the control section 39 judges whether the woofer 1 is defective by comparing the captured sound signal amplified by the third amplifier 38 with the sound signal generated by the sound source 30 (step ST12).

[0049] If the defect judging section 40 has judged that the woofer 1 is defective (YES in step ST12), the correction value calculating section 42 calculates at least one of a correction value for the gain per frequency in the sound signal of the sound output by the woofer 1 and a correction value for the gain per frequency in the sound signal of the sound output by the tweeter 2 (step ST13).

[0050] If the defect judging section 40 has judged that the woofer 1 is not defective (NO in step ST12), the control section 39 repeatedly executes step ST11 and step ST12 until it is judged in step ST12 that the woofer 1 is defective.

[0051] As the next step after step ST13, the control section 39 executes step ST10 again. Here, the control section 39 judges whether the woofer 1 is defective based on the defect judgment result in step ST12 by the defect judgment section 40, and further judges whether the woofer 1 has been repaired.

[0052] If the control section 39 judges that the woofer 1 is defective and the woofer 1 has not been repaired (YES in step ST10), the switch control section 41 of the control section 39 controls the switch 37 to switch the tweeter 2 to function as a sound output element (step ST14).

[0053] Further, in step ST14, the correction value calculation section 42 of the control section 39 outputs the correction value calculated in step ST13 to at least one of the first correction filter 31 and the second correction filter 32.

[0054] According to step ST14, if the correction value calculation section 42 has output a correction value to the first correction filter 31 based on an audio signal whose gain per frequency has been corrected by the first correction filter 31, the woofer 1 outputs a warning tone. According to step ST14, if the correction value calculation section 42 has output a correction value to the second correction filter 32 based on an audio signal whose gain per frequency has been corrected by the second correction filter 32, the tweeter 2 outputs a warning tone.

[0055] Through the above operation, a defect judgment (including judgment of a change in frequency characteristics that has exceeded a tolerance) can be performed simultaneously with the warning sound output by capturing the sound of the tweeter 2. Furthermore, in the event that the woofer 1 is defective, the warning sound that has changed due to the defect of the woofer 1 is regulated by operating the tweeter 2 as a loudspeaker, thereby reducing circumstances under which the warning sound is not perceived by a user.

[0056] The signal processing of the defect judgment by the defect judgment section 40, the calculation of the correction value by the correction value calculation section 42, etc., require adjustment depending on the system environment such as the installation location of the sound output device 101, etc., and the main factors therefor in the first embodiment may be transmission characteristics resulting from the relative positional relationship between the woofer 1 as a speaker for warning sound reproduction and the tweeter 2 functioning as a microphone, or external noise.

[0057] As described above, in the first embodiment, the woofer 1 and the tweeter 2 constitute a coaxial speaker and are fixed to each other, so that changes in the relative distance and angle between the woofer 1 and the tweeter 2 are not easily generated. Furthermore, the woofer 1 and the tweeter 2 are in contact with each other, so they are not easily influenced by external noise. This facilitates parameter adjustment during signal processing, such as defect judgment by the defect judgment section 40, calculation of a correction value by the correction value calculation section 42, and so on.

[0058] In addition, in the first embodiment, in order to differentiate the tweeter 2 as the second loudspeaker, an explanation is given of a structure in which the woofer 1 is used as the first loudspeaker, wherein the first loudspeaker is not limited to the woofer 1. As the woofer 1 in the coaxial loudspeaker, a woofer 1 with a wideband characteristic is generally not used.

[0059] Therefore, sufficient power can be provided to the woofer 1 independently during warning tone playback. Furthermore, the tweeter 2, as a second speaker, also has a microphone power with its small sound receiving section, with which sounds in the band range output by the woofer 1 can be received. If necessary, sufficient sound output power can be provided to the tweeter 2 by the second correction filter 32 correcting the gain per frequency of the sound signal using the correction value calculated by the correction value calculation section 42.

[0060] As an example of calculating the correction value by the correction value calculating section 42, a method for calculating a correction value having an inverse characteristic that cancels the difference between the sound signal generated by the sound source 30 during normal playback and the sound signal of the sound picked up by the tweeter 2 can be cited. This makes it possible to approximate the normal warning sound.

[0061] The precise configuration of the first correction filter 31 and the second correction filter 32 can be changed based on the analysis of the defect judgment section 40 or the design considerations. Furthermore, the correction value calculation section 42 may not output any correction value to the first correction filter 31. In this case, the woofer 1 outputs a sound based on an uncorrected sound signal. Furthermore, the control section 39 may also control the woofer 1 so that it does not output any sound if the defect judgment section 40 has judged that the woofer 1 is defective.

[0062] In addition to the above operation, in order to improve the defect judgment precision, the sound output device 101 may use a conventional defect diagnosis method by means of impedance measurement together with the above-described defect judgment by the defect judgment section 40.

[0063] Before the sound output device 101 plays the warning tone, the sound output device 101 can also perform a pre-diagnosis by having the woofer 1 output a test tone and the tweeter 2 intercept the test tone in question. For example, the test tone is a startup tone during system startup, etc.

[0064] The sound output device 101 can also be used for other purposes such as music playback, etc., when it does not output a warning tone or test tone. Since the woofer 1 and tweeter 2 of the sound output device 101 are coaxial speakers, it can have a wide reproduction band and is suitable for music playback.

[0065] For example, the sound output device 101 may also mix a test tone that is imperceptible to humans (a tone outside the audible range, a tone used as a masking effect, etc.) with the sound output from the woofer 1 and perform the above defect judgment based on the test tone.

[0066] In this case, however, switch 37 must be switched immediately, so that tweeter 2 functions as a sound pickup element. Therefore, there is a risk that a sound emitted immediately before by tweeter 2 could negatively affect tweeter 2's sound pickup after switching (for example, noise interference due to vibrations of the cone material).

[0067] To prevent this, the switch control section 41 controls, based on a sound signal of a sound output by the tweeter 2, the switch 37 switches the tweeter 2 to function as a sound pickup element.

[0068] More specifically, for example, the switch control section 41 judges, in the sound outputted from the tweeter 2, a timing at which noise is small, the convergence time is short, and also the volume is small (for example, a timing at which vibration of the cone material is small, etc.), and at this timing, performs control by which the switch 37 switches the tweeter 2 to function as a sound pickup element.

[0069] In the following, a first modification of the speaker unit 100 according to the first embodiment will be explained with reference to the drawings. Fig. Fig. 5 is a cross-sectional view showing a speaker unit 102 according to the first modification. As shown in Fig. 5, the speaker unit 102 comprises a woofer 50 and a tweeter 51. Also in the first modification, the explanation is given with respect to a structure in which a woofer is used as the first speaker and a tweeter is used as the second speaker, wherein the first speaker according to the first modification may also be a speaker other than a woofer, and the second speaker may be a speaker other than a tweeter. In the Fig. 5, the above-described magnetic circuit 11, the frame section 13, etc. are not shown for the sake of simplicity.

[0070] In the present modification, the sound output device 101 further includes a reflection plate 52 that reflects sound output from the woofer 50 toward the tweeter 51. Examples of the material of the reflection plate 52 include metal, plastic, etc.

[0071] More precisely, the woofer includes 50, as in Fig. 5, a woofer cone 50a (first speaker cone) that emits sounds by vibrating. The tweeter 51 includes a tweeter cone 51a (second speaker cone) that emits sounds by vibrating.

[0072] The tweeter cone 51a of the tweeter 51 is disposed at the center of a sound output surface B of the woofer cone 50a of the woofer 50. The reflection plate 52 is disposed at a position opposite the tweeter cone 51a of the tweeter 51.

[0073] More specifically, the woofer cone 50a of the woofer 50 has a truncated cone shape, in which the larger of the two base surfaces has no bottom surface. The woofer cone 50a has a side surface of the inner side of the truncated cone as the sound output surface B, and the tweeter cone 51a of the tweeter 51 is positioned at the center of the sound output surface B with respect to the smaller of the two base surfaces of the truncated cone.

[0074] The tweeter cone 51a of the tweeter 51 has a truncated cone shape, in which the larger of the two base surfaces has no bottom surface. The reflection plate 52 has a spherical dome shape, with the inner surface of the spherical dome facing the smaller of the two base surfaces of the truncated cone in the tweeter cone 51a of the tweeter 51. Furthermore, in the reflection plate 52, the inner surface of the spherical dome is designed such that it covers the tweeter cone 51a of the tweeter 51. Furthermore, the reflection plate 52 is placed on the inner surface of the truncated cone in the woofer cone 50a of the woofer 50.

[0075] As stated above, by arranging the reflection plate 52, the woofer cone 50a of the woofer 50, and the tweeter cone 51a of the tweeter 51, a sound output from the woofer 50 can be reflected by the reflection plate 52 toward the tweeter 51. Therefore, the sound pickup characteristic of the tweeter 51 in picking up a sound output from the woofer 50 can be improved.

[0076] In the first modification, the reflection plate 52 faces the tweeter cone 51a of the tweeter 51. Therefore, when a sound is output from the tweeter 51, the reflection plate 52 easily interferes with the directivity of the sound. Therefore, the structure of the woofer 50 and tweeter 51 in the first modification is preferably used when the structure of the sound output device 101 is one in which only a warning sound is output. In this case, the sound output device 101 uses the tweeter 51 as a speaker only when the woofer 50 is defective, so the influence of the reflection plate 52 can be minimized.When the sound output device 101 uses the tweeter 51 as a speaker, the correction value calculation section 42, when calculating a correction value for the gain per frequency in the sound signal of the sound output from the tweeter 51, calculates a correction value for the sound output from the tweeter 51 including the influence of the reflection plate 52.

[0077] Next, a second modification of the speaker unit 100 according to the first embodiment will be explained with reference to the drawings. Fig. Fig. 6 is a cross-sectional view showing a speaker unit 103 according to the second modification. Compared with the first modification, the speaker unit 103 according to the second modification includes a reflection plate 60 instead of the reflection plate 52. Examples of the material of the reflection plate 60 include metal, plastic, etc. Fig. 6, the above-described magnetic circuit 11, the frame section 13, etc. are not shown for the sake of simplicity.

[0078] The reflection plate 60 is positioned at the edge of the woofer cone 50a of the woofer 50. More specifically, the reflection plate 60 is positioned at a portion corresponding to the edge of the larger of two base surfaces of the truncated cone at the woofer cone 50a of the woofer 50.

[0079] More specifically, the reflection plate 60 has a truncated cone shape in which both base surfaces have no bottom surface. Because the reflection plate 60 has a truncated cone shape in which both base surfaces have no bottom surface, the portion opposite the tweeter cone 51a of the tweeter 51 is a hollow space. The portion of the reflection plate 60 corresponding to the edge of the larger of the two base surfaces of the truncated cone is connected to the portion corresponding to the edge of the larger of the two base surfaces of the truncated cone in the woofer cone 50a of the woofer 50. The section on the reflection plate 60 which corresponds to the edge of the smaller of the two base surfaces of the truncated cone is positioned on the side facing away from the tweeter cone 51a of the tweeter 51 with respect to the section which corresponds to the larger base area of ​​the two base surfaces of the truncated cone on the woofer cone 50a of the woofer 50.

[0080] In other words, the reflection plate 60 is a side wall formed at a portion corresponding to the edge of the larger of two base surfaces of the truncated cone in the woofer cone 50a of the woofer 50. The side wall in question has a conical shape extending from the portion corresponding to the edge of the larger of the two base surfaces of the truncated cone in the woofer cone 50a of the woofer 50 toward the inner side of the side facing away from the tweeter cone 51 of the tweeter 51.

[0081] As stated above, by arranging the reflection plate 60, the woofer cone 50a of the woofer 50, and the tweeter cone 51a of the tweeter 51, a sound output from the woofer 50 can be reflected by the reflection plate 60 toward the tweeter 51. Therefore, the sound pickup characteristic of the tweeter 51 in picking up a sound output from the woofer 50 can be improved.

[0082] In the second modification, the reflection plate 60 is placed on the periphery of the woofer cone 50a of the woofer 50. Therefore, when a sound is output from the tweeter 51, the reflection plate 60 is not likely to interfere with the directivity of that sound. Therefore, the structure of the woofer 50 and tweeter 51 according to the second modification is preferably applied when the structure of the sound output device 101 is one in which music, etc., is output in addition to a warning sound. This can improve the sound pickup characteristic of the tweeter 51 while minimizing a deterioration in the sound quality of the sounds output from the tweeter 51.

[0083] The respective functions of the defect judgment section 40, the switch control section 41, and the correction value calculation section 42 in the control section 39 of the sound output device 101 are realized by a processing circuit. That is, the control section 39 of the sound output device 101 includes a processing circuit for executing the processing of the respective steps shown in Fig. 3 and Fig. 4. The processing circuitry may be dedicated hardware, but it may also be a CPU (Central Processing Unit) that executes programs stored in memory.

[0084] Fig. 7A is a block diagram showing the hardware structure for realizing the functions of the control section 39 of the sound output device 101. Fig. 7B is a block diagram showing the hardware structure for executing software for realizing the functions of the control section 39 of the sound output device 101.

[0085] If the processing circuit is one in Fig. 7A, the processing circuit 70 corresponds, for example, to a simple circuit, a complex circuit, a programmed processor, parallel programmed processors, ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or a combination thereof.

[0086] In the control section 39 of the sound output device 101, the respective functions of the defect judgment section 40, the switch control section 41, and the correction value calculation section 42 may be realized by separate processing circuits, but these functions may also be realized as a whole by a single processing circuit.

[0087] If the processing circuit is a Fig. 7B, the control section 39 of the sound output device 101 implements the respective functions of the defect assessment section 40, the switch control section 41, and the correction value calculation section 42 through software, firmware, or a combination of software and firmware. The software or firmware is stored in a memory 72, represented as a program.

[0088] The processor 71 reads out programs stored in the memory 72 and executes them, thereby realizing the respective functions of the defect assessment section 40, the switch control section 41, and the correction value calculation section 42 in the control section 39 of the sound output device 101. That is, in the control section 39 of the sound output device 101, the respective functions are executed by the processor 71, the memory 72 is included for storing programs, by which the processing of the Fig. 3 and Fig. 4 shown individual steps must be carried out.

[0089] Through these programs, the order or method of the defect assessment section 40, the switch control section 41, and the correction value calculation section 42 are respectively executed on a computer in the control section 39 of the sound output device 101. The memory 72 may also be a computer-readable storage medium in which programs are stored so that a computer functions as the defect assessment section 40, the switch control section 41, and the correction value calculation section 42 in the control section 39 of the sound output device 101.

[0090] The processor 71 corresponds, for example, to a CPU (Central Processing Unit), a processing device, a computing device, a processor, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor), etc.

[0091] The memory 72 corresponds, for example, to a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically-EPROM), etc., a magnetic disk such as a hard disk, a floppy disk, etc., a floppy disk, an optical disk, a compact disc, a MiniDisc, a CD (Compact Disc), a DVD (Digital Versatile Disc), etc.

[0092] In the control section 39 of the sound output device 101, the respective functions of the defect judgment section 40, the switch control section 41, and the correction value calculation section 42 can also be realized partly by a special hardware and partly by a software or firmware.

[0093] For example, the functions of the defect assessment section 40 are implemented by a processing circuit as dedicated hardware. The functions of the switch control section 41 and the correction value calculation section 42 can also be implemented by the processor 71 reading and executing programs stored in the memory 72. Thus, the processing circuit can implement the respective functions described above through hardware, software, firmware, or a combination thereof.

[0094] As stated above, the sound output device 101 according to the first embodiment includes a first speaker (woofer 1) and a second speaker (tweeter 2) each outputting sounds, and a switch 37 for switching the second speaker to function as a sound output element that converts a sound signal into a sound or to function as a sound pickup element that converts a sound into a sound signal, wherein the first speaker and the second speaker constitute a coaxial speaker.

[0095] According to this structure, the first speaker and the second speaker form a coaxial speaker and are fixed to each other, so that changes in the relative distance and angle between the first speaker and the second speaker are not easily caused. This can suppress deterioration of the captured audio signal, thus improving the accuracy of noise assessment.

[0096] With this configuration, the first speaker and the second speaker are positioned adjacent to each other, making them less susceptible to external noise. This also suppresses deterioration of the captured audio signal, improving the accuracy of noise assessment. Furthermore, with this configuration, the second speaker can function as a sound pickup element, eliminating the need for a separate sound pickup element such as a microphone.

[0097] In the sound output device 101 according to the first embodiment, the first speaker is a woofer 1, and the second speaker is a tweeter 2. According to this structure, the woofer 1 and the tweeter 2 constitute a coaxial speaker and are fixed to each other, so that changes in the relative distance and angle between the woofer 1 and the tweeter 2 are not likely to occur. This can suppress deterioration of the collected sound signal, so that the precision of noise judgment can be improved.

[0098] The sound output device 101 according to the first embodiment further includes a defect judging section 40 that judges whether the first speaker is defective based on a captured sound signal that the second speaker (tweeter 2) has acquired by capturing a sound output from the first speaker (woofer 1).

[0099] This design allows for the first speaker to be judged to be defective. If no defect assessment is performed, the second speaker can be used as a normal speaker, supporting the warning sound after a defect assessment, or for purposes other than warning sound, such as music playback.

[0100] The sound output device 101 according to the first embodiment further includes a switch control section 41 that performs control by which the switch 37 switches the second speaker (tweeter 2) to function as a sound output element when it has been judged by the defect judging section 40 that the first speaker (woofer 1) is defective.

[0101] According to this structure, if the first speaker is defective, the second speaker can output a sound instead, or a sound changed by a defect of the first speaker can be regulated by a sound output from the second speaker.

[0102] The sound output device 101 according to the first embodiment includes a correction value calculation section 42 that calculates, in the case where the defect judgment section 40 has judged a defect of the first loudspeaker (woofer 1), at least either a correction value for the gain per frequency in a sound signal of a sound output by the first loudspeaker or a correction signal for the gain per frequency in a sound signal of a sound output by the second loudspeaker, a first correction filter 31 that corrects the gain per frequency in the sound signal of the sound output by the first loudspeaker based on the correction value calculated by the correction value calculation section 42, and a second correction filter 32 that, based on the correction value calculated by the correction value calculation section 42, calculates the gain per frequency in the sound signal of the sound,which is output by the second speaker,

[0103] According to this structure, when the first speaker is defective, a sound output from the first speaker or a sound output from the second speaker can be regulated based on the calculated correction value.

[0104] The sound output device 101 according to the first embodiment further includes a switch control section 41 that performs control by the switch 37, based on a sound signal of a sound output from the second speaker (tweeter 2), to switch the second speaker to function as a sound pickup element. According to this configuration, based on a sound output from the second speaker, the second speaker can be switched to function as a sound pickup element at an appropriate timing.

[0105] The sound output device 101 according to the first embodiment also includes a reflection plate 52 that directs the sound output by the first speaker (woofer 1) toward the second speaker (tweeter 2). According to this structure, the sound output by the first speaker can be directs the sound output toward the second speaker. Therefore, the sound pickup characteristic of the second speaker can be improved when picking up the sound output from the first speaker.

[0106] In the sound output device 101 according to the first embodiment, the first speaker (woofer 1) includes a woofer cone 50a that outputs sound by vibration, and the second speaker (tweeter 2) has a tweeter cone 51a that outputs sound by vibration, wherein the tweeter cone 51a is disposed at the center of the sound output surface B of the woofer cone 50a, and the reflection plate 52 is disposed at a position opposite to the tweeter cone 51a.

[0107] According to this structure, a sound output by the woofer cone 50a of the first speaker can be properly reflected toward the tweeter cone 51a of the second speaker. Therefore, the pickup characteristics of the second speaker can be improved when picking up a sound output from the first speaker.

[0108] In the sound output device 101 according to the first embodiment, the first speaker (woofer 1) includes a woofer cone 50a that outputs sounds by vibration, and the second speaker (tweeter 2) includes a tweeter cone 51a that outputs sounds by vibration, wherein the tweeter cone 51a is disposed at the center of a sound output surface B of the woofer cone 50a, and the reflection plate 60 is disposed at the periphery of the woofer cone 50a.

[0109] According to this structure, when a sound is output from the tweeter 51, the reflection plate 60 is not likely to interfere with the directivity of the sound because the reflection plate 60 is positioned at the periphery of the woofer cone 50a of the woofer 50. This can improve the sound pickup characteristics of the tweeter 51 while minimizing a deterioration in the sound quality of the sound output from the tweeter 51. Any modification of the components of the embodiments or omission of any components of the embodiments is possible. Industrial application

[0110] By the sound output device according to the present disclosure, deterioration of a captured sound signal can be suppressed and the precision of defect judgment can be improved, so that application to a technique for regulating a sound signal based on a captured sound signal is possible. Explanation of reference symbols 1 woofer 2 tweeters 10 Woofer input connector 11 Magnetic circuit 12 woofer cones 13 Frame section 20 Tweeter input connector 21 tweeter cones 30 sound source 31 First correction filter 32 Second correction filter 33 First Amplifier 34 Second amplifier 35 First band-range filter 36 Second band-range filter 37 switches 38 Third amplifier 39 Tax Section 40 Defect Assessment Section 41 Switch control section 42 Correction value calculation section 50 woofers 50a woofer cone 51 tweeters 51a Tweeter cone 52 reflection plate 60 reflection plate 70 processing circuit 71 processor 72 storage 100 speaker unit 101 Sound output device 102 Loudspeaker unit 103 Loudspeaker unit

Claims

[1] Sound output device (101) comprising a first loudspeaker (1, 50) and a second loudspeaker (2, 51), each emitting tones, and a switch (37) for switching the second loudspeaker (2, 51) so that it functions as a sound output element that converts a sound signal into a sound, or functions as a sound pickup element that converts a sound into a sound signal, wherein the first loudspeaker (1, 50) and the second loudspeaker (2, 51) form a coaxial loudspeaker, and wherein the sound output device (101) further comprises: a switch control section (41) which, based on a sound signal of a sound output from the second speaker (2, 51), performs control by which the switch (37) switches the second speaker (2, 51) to function as a sound pickup element. [2] Sound output device (101) according to claim 1, wherein the first loudspeaker (1, 50) is a woofer (1, 50), and the second loudspeaker (2, 51) is a tweeter (2, 51). [3] The sound output device (101) according to claim 1, further comprising a defect judging section (40) that judges whether the first speaker is defective based on a picked-up sound signal that the second speaker (2, 51) has acquired by picking up a sound output from the first speaker (1, 50). [4] The sound output device (101) according to claim 3, further comprising a switch control section (41) that performs control by which the switch (37) switches the second speaker (2, 51) to function as a sound output element when it has been judged by the defect judging section (40) that the first speaker (1, 50) is defective. [5] Sound output device (101) according to claim 3, further comprising a correction value calculation section (42) which, in the event that the defect judgment section (40) has judged a defect of the first loudspeaker (1, 50), calculates at least either a correction value for the gain per frequency in a sound signal of a sound output by the first loudspeaker (1, 50) or a correction value for the gain per frequency in a sound signal of a sound output by the second loudspeaker (2, 51), a first correction filter (31) which corrects the gain per frequency in the sound signal of the sound output by the first loudspeaker (1, 50) based on the correction value calculated by the correction value calculation section (42), and a second correction filter (32) that corrects the gain per frequency in the sound signal of the sound output by the second speaker (2, 51) based on the correction value calculated by the correction value calculation section (42). [6] The sound output device (101) according to claim 1, further comprising a reflection plate (52, 60) that directs a sound output by the first speaker (1, 50) to the second speaker (2, 51). [7] Sound output device (101) according to claim 6, wherein the first loudspeaker (1, 50) has a first loudspeaker cone (50a) which emits sounds by oscillation, the second loudspeaker (2, 51) has a second loudspeaker cone (51a) which emits sounds by oscillation, the second loudspeaker cone (51a) is placed in the center of a sound output surface of the first loudspeaker cone (50a), and the reflection plate (52) is placed at a location opposite the second loudspeaker cone (51a). [8] Sound output device (101) according to claim 6, wherein the first loudspeaker (1, 50) has a first loudspeaker cone (50a) which emits sounds by oscillation, the second loudspeaker (2, 51) has a second loudspeaker cone (51a) which emits sounds by vibrating, and the second loudspeaker cone (51a) is placed in the center of a sound output surface of the first loudspeaker cone (50a), and the reflection plate (60) is placed at the edge of the first loudspeaker cone (50a).

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