Acoustic signal amplifier

Abstract

The invention relates to an acoustic signal amplifier adapted for connection to a loudspeaker and for communication with a digital computer via at least one first data bus. The amplifier is characterized in that it comprises: a sampling register including several current samples captured at a sampling frequency; a first threshold volume register associated with a first threshold value; a first comparator adapted for comparing current samples from the sampling register to the first threshold value of the first volume register; a first time counter adapted for being triggered when a compared current sample is greater than the first threshold value and adapted for being reset when another compared current sample is less than the first threshold value; and an alert unit.adapted to send an alert on the first data bus to the digital computer when the first time counter reaches a first threshold time value. Figure 2a,

Description

Title of the invention: Acoustic signal amplifier technical field

[0001] The present invention relates to an acoustic signal amplifier adapted to be connected to loudspeakers and a volume control system comprising this amplifier. Previous technique

[0002] In the context of using loudspeakers in a vehicle, particularly for listening to the radio during a journey, certain inconveniences caused by variations in loudspeaker volume have been identified.

[0003] These volume variations are due in particular to a non-linearity of the impedance of the loudspeakers as a function of the frequency of the acoustic signal to be diffused.

[0004] Several solutions have been considered to reduce these volume variations. One solution involves equipping vehicles with loudspeakers whose impedance non-linearity with respect to signal frequency is less pronounced. However, such loudspeakers are more expensive. This solution is therefore not satisfactory.

[0005] Another solution was considered with the introduction of digital control units (DCUs) in vehicles capable of signal processing, also known as Digital Signal Processors (DSPs). This solution consists of compensating for the non-linearity of the loudspeakers at the DCU level by directly adjusting their respective volumes based on current samples measured from an acoustic signal from a signal amplifier connected to the loudspeakers. Since the frequency of an acoustic signal can reach 20 kHz, the sampling frequency required to utilize the signal in its entirety is therefore at least twice 20 kHz.

[0006] In this solution, the compensation of the non-linearity of the loudspeakers by the digital computer involves reading samples of the output signal (in this case, a current) from the amplifier, transmitting these samples to the digital computer, and, based on the transmitted samples, adjusting the loudspeaker volume. The transmission of the current samples from the amplifier to the digital computer is carried out via a bus, for example, an "Inter-Integrated circuit", I2C, or an "Integrated Interchip Sound", I2S bus.

[0007] In order to transmit all the current samples to the digital computer in real time, the bus used must therefore allocate a significant bandwidth due to the sampling frequency exceeding 40 kHz required for sampling the acoustic signal. This can be particularly problematic for other applications communicating with the digital computer and also using this bus.

[0008] In practice, the current samples are therefore not transmitted to the digital computer at a frequency higher than 40 kHz, even though the signal is indeed sampled at this frequency. They are actually transmitted at a frequency on the order of a few kHz. Consequently, the digital computer does not possess all the sampled acoustic information that will be transmitted to the loudspeakers and is therefore unable to compensate for the non-linearity of the loudspeaker impedance within a reasonable timeframe. The current solution is therefore not entirely satisfactory.

[0009] The invention improves this situation. Presentation of the invention

[0010] One objective of the present invention is therefore to provide an acoustic signal amplifier, adapted to be connected to a loudspeaker, and adapted to communicate with a digital computer via at least a first data bus, the amplifier comprising: - a sampling register comprising several current samples captured at a sampling frequency, - a first threshold volume register associated with a first threshold value, - a first comparator adapted to compare current samples from the sampling register to the first threshold value of the first volume register, - a first time counter, adapted to be triggered when a compared current sample is greater than the first threshold value and adapted to be reset when another compared current sample is less than the first threshold value, - an alert unit, adapted to send an alert on the first data bus to the digital computer when the first time counter reaches a first threshold time value.

[0011] Optionally, the amplifier includes: - a second threshold volume register associated with a second threshold value, - a second comparator adapted for comparing current samples from the sampling register to the second threshold value of the second volume register, - a second time counter, adapted to be triggered when a compared current sample is greater than the second threshold value and adapted to be reset when another compared current sample is lower than the second threshold value, and

[0012] wherein the alert unit is also adapted to send an alert on the first data bus to the digital computer when the second time counter reaches a second threshold time value.

[0013] Optionally, the amplifier includes: - a threshold volume deviation register associated with a threshold deviation value, - a third comparator adapted to compare a difference between two successive current samples from the sampling register to the threshold deviation value of the volume deviation register, - a third threshold volume register associated with a current volume threshold value, - a fourth comparator adapted to compare a current speaker volume received via a data bus from the digital computer to the current volume threshold value, and

[0014] and wherein the alerting unit is also adapted to send an alert on the first data bus to the digital computer when the difference between two successive current samples is greater than the threshold deviation value and the current volume of the loudspeaker is greater than the threshold current volume value

[0015] Optionally, the amplifier includes a signal transmission unit configured to send current samples of the acoustic signal on the first data bus to the digital computer at a sending frequency lower than the sampling frequency.

[0016] Optionally, the amplifier includes a signal receiving unit adapted to receive modified current samples via a second data bus, the modified current samples corresponding to the current samples sent by the signal transmission unit and modified following processing of these samples by the digital computer.

[0017] This application also presents a volume control system comprising: - an acoustic signal amplifier as described previously, - a loudspeaker connected to the amplifier and adapted to reproduce an acoustic signal received from the amplifier, - a first data bus linking the amplifier to a digital computer and adapted to transmit an alert and current samples from the amplifier to the digital computer, - a second data bus linking the amplifier to the digital computer and adapted to transmit current samples from the digital computer to the amplifier, - a digital calculator, adapted to modify a speaker volume when it receives an alert, the volume modification corresponding to a transmission of modified current samples on the second data bus to the amplifier.

[0018] Optionally, the first data bus is an Inter-Integrated circuit, I2C bus, and in which the second data bus is an Integrated Interchip Sound, I2S bus.

[0019] Optionally, an electric current sensor adapted to measure an electric current from an acoustic signal of the amplifier.

[0020] A volume system according to any of the preceding options may also be installed in a vehicle. Brief description of the drawings

[0021] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0022] [Fig-1] presents an example of a volume control system.

[0023] [Fig.2a] presents a first example of an acoustic signal amplifier.

[0024] [Fig.2b] presents a second example of a complete acoustic signal amplifier comment. Description of the implementation methods

[0025] This disclosure presents an acoustic signal amplifier and a volume control system comprising such an amplifier. The volume system can advantageously be integrated into a vehicle.

[0026] An example of a volume control system 1 is shown in particular in [Fig.1].

[0027] The example volume control system 1 includes an acoustic signal amplifier 2 (hereinafter referred to as amplifier 2), an example of which is shown in particular in [Fig. 2a] and [Fig. 2b]. The example control system also includes a loudspeaker 3 connected to the amplifier 2. The loudspeaker 3 is adapted to reproduce an acoustic signal received from the amplifier 2.

[0028] The acoustic signal corresponds to an output electrical current transmitted from the amplifier 2 to the loudspeaker 3.

[0029] In some examples, the amplifier 2 can be connected to several loudspeakers 3 so that each of the loudspeakers 3 can diffuse an acoustic signal received from the amplifier 2. However, reference will be made to a loudspeaker 3 in the remainder of this application, but it is not excluded that there may be several.

[0030] The example volume control system 1 also includes a digital computer 4 and a memory 4L. The digital computer 4 can, for example, be a processor or a microcontroller. In some examples, the digital computer 4 is a digital computer capable of performing signal processing. It includes access to memory 41 so that it can use the information it contains.

[0031] The memory 41 may, for example, include a ROM (Read-Only Memory), a RAM (Random Access Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or any other type of suitable storage medium allowing, in particular, the reading of code instructions. The memory may, for example, include optical, electronic, or magnetic storage media.

[0032] The example volume control system 1 further includes a first data bus B1 connecting the amplifier 2 to the digital computer 4. The first data bus B1 is adapted to transmit an alert from the amplifier 2 to the digital computer 4. The first data bus B1 can be adapted to transmit current samples from the amplifier 2 to the digital computer 4. The memory 41 can thus be used to store these samples.

[0033] In examples, the first data bus B1 is an “Inter-Integrated circuit” bus, I2C.

[0034] The example volume control system 1 also includes a second data bus B2 linking the amplifier 2 to the digital computer 4. The second data bus B2 is adapted to transmit current samples from the digital computer 4 to the amplifier 2.

[0035] In examples, the second data bus B2 is an “Integrated Interchip Sound” bus, I2S.

[0036] The digital computer 4 is further adapted to modify the volume of the loudspeaker 3 when it receives an alert via a data bus from the amplifier 2. The modification of the volume of the loudspeaker 3 can correspond to a transmission of modified current samples on the second data bus B2 to the amplifier 2. It is understood here that the modification of the volume of several loudspeakers connected to the amplifier 2 can be carried out in the same way as for a single loudspeaker.

[0037] The example of volume control system 1 further includes an electric current sensor 5 adapted to measure an electric current from an acoustic signal of the amplifier 2.

[0038] Reference is now made to [Fig. 2a] which shows an example of an amplifier of acoustic signal 2. This example of an amplifier 2 is suitable for connection to one or more loudspeaker(s) 3. It is also suitable for communicating with a digital computer 4 via at least one first data bus Bl. In this case, [Fig. 2b] represents another example of a complementary amplifier that can be integrated into the example shown in [Fig. 2a] but which has been shown in a separate figure entire to avoid any confusion due to too many elements in the same figure. In other words, the amplifier example shown in [Fig.2a] can include all the elements of the example shown in [Fig.2b] that it does not already include, and vice versa.

[0039] The amplifier example 2 thus includes a sampling register Rfe comprising several current samples (E1, E2, ..., En, in [Fig. 2b]) captured at a sampling frequency. The current samples captured at the sampling frequency are acquired from an output current of the amplifier 2 and are stored in the sampling register Rfe. These samples can, for example, be acquired by the current sensor 5. The current sensor 5 can, for example, be controlled by a controller 24, for example a microprocessor integrated into the amplifier 2. In which case, the sampling register Rfe can constitute part of the memory of the controller 24, another part being devoted to storing the code instructions for controlling the sampling.

[0040] The sampling register Rfe can be managed by a first-in, first-out (FIFO) method. The sampling frequency, since the output current of amplifier 2 is an acoustic signal, is advantageously greater than 40 kHz to satisfy the Shannon criterion.

[0041] The amplifier 2 also includes a first threshold volume register RI associated with a first threshold value. The first threshold value may correspond to a value in amperes (A) or a value in decibels (dB).

[0042] In examples where the first threshold value corresponds to a value in decibels, the amplifier 2 may include an ampere-to-decibel (ADC) converter adapted to convert a current value in amperes from the sampling register Rfe into a value in decibels. The ADC converter may, for example, be a software unit implemented by the controller 24. In some examples, the code instructions for implementing the software unit acting as the ADC converter may also be stored in the memory of the controller 24.

[0043] The first threshold value of the first threshold volume register RI can be assigned and / or modified by a controller, for example by the controller 24 integrated in the amplifier 2. More generally, all the values ​​associated with registers or counters included in the amplifier 2 which will be presented in this disclosure can be assigned and / or modified by a controller, for example by the controller 24.

[0044] Amplifier 2 also includes a first comparator CL. The first comparator Cl is adapted to compare successive current samples from the register sampling Rfe to the first threshold value of the first threshold volume register RI. The current samples of the sampling register Rfe can, for example, be compared by the first comparator Cl sequentially according to their order of arrival in the sampling register Rfe.

[0045] In this case, when the first threshold value is a value in decibels, the value in amperes associated with the current sample included in the sampling register Rfe is converted into a value in decibels by the ampere-decibel converter CAD before being compared by the first comparator Cl.

[0046] In this way, it is possible to compare successive current values ​​in amperes or volume values ​​in decibels corresponding to the output signal of amplifier 2.

[0047] Amplifier 2 also includes a first time counter Cpl. The first time counter Cpl is adapted to be triggered when a compared current sample exceeds the first threshold value. For the purposes of this application, "triggered" means that the time counter increments or decrements a counter. In other words, when a sample from the compared sampling register Rfe exceeds the threshold value, whether measured in decibels or amperes, the time counter is triggered.

[0048] The first Cpl time counter is also adapted to be reset when another compared current sample is less than the first threshold value. By reset, it should be understood to be returned to a default value. The default value may be 0 when the counter is incremented on triggering or may be a predetermined value when the counter is decremented on triggering.

[0049] The amplifier 2 further includes an alert unit 21. The alert unit 21 is adapted to send an alert on the first data bus B1 to the digital computer 4 when the first time counter Cpl reaches a first threshold time value.

[0050] Thus, the combination of the first register RI, the first comparator Cl, the counter Cpl, and the alert unit 21 makes it possible to trigger an alert when successive current samples from the sampling register Rfe exceed the first threshold value (in dB or current) during a first threshold time value. This arrangement therefore makes it possible to detect a problematic situation in which a high noise level is emitted for a specific duration and to alert the digital computer 4 so that it can take appropriate action. The digital computer 4 can, for example, reduce the volume of the loudspeaker 3 in order to protect a user's hearing.

[0051] In some examples, the first threshold value is between 105 and 115 dB and the first threshold time value is between 15 and 25 seconds. In others For example, the first threshold value is between 108 and 112 dB and the first threshold time value is between 18 and 22 seconds.

[0052] In one embodiment, the amplifier 2 may also include a second threshold volume register R2 associated with a second threshold value. The second threshold value may correspond to a value in amperes (A) or a value in decibels (dB). The second threshold value is lower than the first threshold value.

[0053] In this embodiment, the amplifier 2 also includes a second comparator C2. The second comparator C2 is adapted to compare current samples from the sampling register Rfe to the second threshold value of the second threshold volume register R2. Similar to the first comparator C1, the aim is to compare successive current samples sequentially according to their order of arrival in the sampling register Rfe.

[0054] In this case, when the second threshold value is a decibel value, the ampere value associated with the current sample included in the sampling register Rfe is converted into a decibel value by the ampere-decibel converter CAD before being compared by the second comparator C2.

[0055] In this embodiment, the amplifier 2 also includes a second time counter Cp2. The second time counter Cp2 is adapted to be triggered when a compared current sample is greater than the second threshold value.

[0056] The second time counter Cp2 is also adapted to be reset when another compared current sample is less than the first threshold value.

[0057] In this embodiment, the alert unit 21 is also adapted to send an alert on the first data bus B1 to the digital computer 4 when the second time counter Cp2 reaches a second threshold time value. The second threshold time value is greater than the first threshold time value.

[0058] Thus, in this embodiment, it is possible to identify both a situation in which the noise level is high and a situation in which the noise level is lower and sustained, such that a user may have become accustomed to this noise level, which could potentially damage their hearing. Sending the alert after this detection thus notifies the digital computer 4 so that it can take appropriate action, for example, reducing the volume of the loudspeaker 3 in order to protect the user's hearing.

[0059] In some examples, the second threshold value is between 100 and 110 dB and the second threshold time value is between 55 and 65 seconds. In other examples, the second threshold value is between 103 and 107 dB and the second The threshold time value is between 58 and 62 seconds.

[0060] Reference is now made to [Fig. 2b] showing another example of an amplifier complementary to amplifier 2 shown with reference to [Fig. 2a]. It is recalled that the elements of this amplifier example that differ from the amplifier example 2 shown in [Fig. 2a] can be incorporated into the example in [Fig. 2a].

[0061] In this case, the amplifier 2 may include a third threshold volume deviation register Re associated with a threshold deviation value. The threshold deviation value may correspond to a value in amperes (A) or a value in decibels (dB).

[0062] The amplifier 2 may include a third comparator C3 adapted to compare a difference between two successive current samples (represented by El and E2 in [Fig. 2b] and more generally by En-1 and En) of the sampling register Rfe to the threshold deviation value of the volume deviation register Re. The difference between two successive samples is represented by the DIF block in [Fig. 2b]. This makes it possible to determine whether a difference in amperes or decibels between two successive samples is greater than the threshold deviation value of the register. In this case, depending on the chosen volume deviation threshold, this can make it possible to identify a sudden change in volume between two samples of the sampling register Rfe.

[0063] Amplifier 2 may include a third threshold volume register R3 associated with a current volume threshold value.

[0064] The amplifier 2 may include a fourth comparator C4 adapted to compare a current volume Vc of the speaker 3 received via a data bus from the digital computer 4 to the current volume threshold value. The aim here is to compare a current volume of the speaker 3, sent by the digital computer 4, to a current threshold value in order to detect whether the current volume exceeds this threshold.

[0065] In this additional embodiment, the alert unit 21 is also adapted to send an alert on the first data bus B1 to the digital computer 4 when: - the difference between two successive current samples is greater than the threshold deviation value, and - the current volume of the speaker is higher than the threshold current volume value.

[0066] This additional embodiment thus makes it possible to identify, in addition to the situations previously described with reference to [Fig. 2a], when the volume of the loudspeaker 3 increases abruptly and the current volume of the loudspeaker 3 is already at a high value. The digital calculator 4 can thus take an appropriate action, for example reducing the volume of the speaker(s) in order to protect the user's hearing.

[0067] In examples, the current volume threshold value is between 45 and 55 dB and is preferably between 48 and 52 dB.

[0068] In examples, the alert unit 21 can also be configured to issue different types of alerts depending on the situation identified.

[0069] In some examples, the amplifier 2 may further include a signal transmission unit 22 configured to send current samples of the acoustic signal on the first data bus B1 to the digital computer at a transmission frequency lower than the sampling frequency. This signal sampling unit 22 thus makes it possible to send samples on the first bus at a frequency lower than the sampling frequency so that these samples can be processed and modified by the digital computer 4 in the event of an alert without congesting the bandwidth of this first bus B1. In this way, the first bus B1 is preserved for other applications that may want to transmit on this bus, for example, to communicate with the digital computer 4.

[0070] In some examples, the amplifier 2 may also include a signal receiving unit 23 adapted to receive modified current samples via the second data bus. The modified current samples correspond to the current samples sent by the signal transmission unit 22 on the first bus and modified following processing of these samples by the digital computer 4.

[0071] Thus, an amplifier 2 according to this disclosure makes it possible to detect situations considered disturbing to users' hearing directly at the amplifier 2 level and to transmit this information to the digital computer 4 by means of an alert so that the latter can take appropriate action. It is therefore not necessary to transmit all current samples on a data bus to the digital computer in order to detect a problematic situation. Current samples can be sent periodically, at a frequency lower than the sampling frequency, and the digital computer 4 can consider processing them as soon as it has received an alert from the amplifier 2 identifying a problematic situation.This allows both to preserve bandwidth on the current sample transmission bus while preserving resources of the digital computer 4 since the identification of problematic solutions from the current samples is carried out by the amplifier 2.

Claims

Demands

1. Acoustic signal amplifier (2), adapted to be connected to a loudspeaker (3), and adapted to communicate with a digital computer (4) via at least a first data bus (B1; B2), the computer (4) being configured to decrease the volume output by the loudspeaker (3) when it receives an alert in order to preserve the user's hearing, the amplifier (2) being characterized in that it comprises: - a sampling register (Rfe) comprising several current samples captured at a sampling frequency, - a first threshold volume register (RI) associated with a first threshold value, - a first comparator (Cl) adapted to compare current samples from the sampling register to the first threshold value of the first threshold volume register (RI), - a first time counter (Cpl),adapted to be triggered when a compared current sample is greater than the first threshold value and adapted to be reset when another compared current sample is less than the first threshold value, - an alert unit (21), adapted to send an alert on at least the first data bus (B1; B2) to the digital computer (4) when the first time counter (Cpl) reaches a first threshold time value.

2. Amplifier (2) according to the preceding claim, characterized in that it comprises: - a second threshold volume register (R2) associated with a second threshold value, - a second comparator (C2) adapted to compare current samples from the sampling register to the second threshold value of the second threshold volume register (R2), - a second time counter (Cp2), adapted to be triggered when a compared current sample is greater than the second threshold value and adapted to be re- initialized when another compared current sample is less than the second threshold value, and in that the alert unit (21) is also adapted to send an alert on at least the first data bus (B1; B2) to the digital computer (4) when the second time counter (Cp2) reaches a second threshold time value.

3. Amplifier (2) according to any one of the preceding claims, characterized in that it comprises: - a threshold volume deviation register (Re) associated with a threshold deviation value, - a third comparator (C3) adapted to compare a difference between two successive current samples of the sampling register to the threshold deviation value of the volume deviation register, - a third threshold volume register (R3) associated with a current volume threshold value, - a fourth comparator (C4) adapted to compare a current volume (Vc) of the loudspeaker received by a data bus from the digital computer (4) to the current volume threshold value, and in that the alert unit (21) is also adapted to send an alert on at least the first data bus (B1;B2) to the digital computer (4) when the difference between two successive current samples is greater than the threshold deviation value and the current volume of the loudspeaker (3) is greater than the threshold current volume value.;

4. Amplifier (2) according to any one of the preceding claims, characterized in that it comprises a signal transmission unit (22) configured to send current samples of the acoustic signal on the at least first data bus (B1; B2) to the digital computer (4) at a sending frequency lower than the sampling frequency.

5. Amplifier (2) according to the preceding claim, characterized in that it comprises a signal receiving unit (23) adapted for receive modified current samples via a second data bus, the modified current samples corresponding to the current samples sent by the signal transmission unit (22) and modified following processing of these samples by the digital computer (4) in order to reduce the volume when the modified samples are played back by the loudspeaker (3).

6. Volume control system (1) comprising: - an acoustic signal amplifier (2) according to any one of the preceding claims, - a loudspeaker (3) connected to the amplifier (2) and adapted to output an acoustic signal received from the amplifier (2), - a first data bus (B1) connecting the amplifier (2) to a digital computer (4) and adapted to transmit an alert and current samples from the amplifier (2) to the digital computer (4), - a second data bus (B2) connecting the amplifier (2) to the digital computer (4) and adapted to transmit current samples from the digital computer (4) to the amplifier (2), - a digital computer (4), adapted to decrease the volume of the loudspeaker (3) when it receives an alert,the decrease in volume corresponding to a transmission of modified current samples on the second data bus (B2) to the amplifier (2).

7. Volume control system (1) according to the preceding claim, wherein the first data bus (B1) is an "Inter-Integrated circuit" bus, I2C, and wherein the second data bus (B2) is an "Integrated Interchip Sound" bus, I2S.

8. Volume control system (1) according to any one of claims 6 to 7, comprising an electric current sensor (5) adapted to measure an electric current from an acoustic signal of the amplifier (2).

9. Vehicle incorporating a volume control system (1) according to any one of claims 6 to 8.

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