JP5538982B2 - Current consumption control device and current consumption control method - Google Patents

Description

  The present invention relates to a current consumption control device and a current consumption control method, and is particularly suitable for use in an apparatus and method for controlling current consumed by an amplifier that supports multiple channels.

  In recent years, many multi-channel sound sources have been provided in order to improve the quality of sound reproduced by an in-vehicle audio device. In order to listen to multi-channel audio, it is necessary to have an amplifier with multi-channel output as well as multiple speakers and subwoofers. For this reason, recent in-vehicle amplifiers tend to have multiple channels. Some amplifiers have as many as 15 channels.

  However, in such a multi-channel amplifier, for example, if a large output is output from all the channels at the same time when a large volume is set, there is a possibility that a large current is consumed so that the fuse is blown. For this reason, it is necessary to limit the current consumption of the amplifier in some way in order to avoid the occurrence of a blown fuse even when outputting sound at a high volume.

  Conventionally, as a mechanism for limiting the current consumption, by reducing the output when the distortion of the audio signal output from the amplifier increases, or by measuring the voltage at both ends of the power supply line by inserting a small resistor A method is known in which the current is measured and the output is reduced when a current exceeding a threshold value is detected. In these methods, the current consumption is limited by lowering the volume by changing the volume. In addition, a technique has been proposed in which a predicted value of current consumption in an amplifier is calculated and an input audio signal to the amplifier is attenuated accordingly (see, for example, Patent Document 1).

JP 2009-253955 A

  However, in the method of reducing the output when the distortion of the audio signal output from the amplifier becomes large, each channel does not output so large that the audio signal is distorted, but the total current is large enough to blow the fuse. It may become. That is, there is a problem in that a large current that can blow the fuse flows before distortion of the audio signal occurs, and it may not be possible to avoid a blown fuse.

  Further, in the method of reducing the output when the current of the power supply line is measured and a current exceeding the threshold is detected, the resistor inserted in the power supply line generates heat when the current flows. As a result, the resistance value increases, and accurate current measurement cannot be performed. For this reason, there is a problem that a large current that can blow the fuse actually flows before detecting a current greater than or equal to the threshold value, and it may not be possible to avoid a blown fuse.

  On the other hand, the technique described in Patent Document 1 can avoid the above-described problem of blown fuses. However, since the current consumption is limited by attenuating the input audio signal to the amplifier, the volume of the output audio is lowered as a whole, as in the case of changing the volume, and there is a problem that a sense of incongruity occurs in the sense of hearing. there were. To avoid this, if the volume is gradually lowered at a speed that is not noticed by the user by slowing down the decay speed, a large current will flow and the fuse will be blown before it is fully attenuated. There was a problem that there was.

  The present invention has been made to solve such a problem, and can prevent the occurrence of a blown fuse by limiting the current consumption in the amplifier without causing a sense of incongruity in the output sound. The purpose is to.

In order to solve the above-described problems, in the present invention, for each of a plurality of channels constituting a multi-channel, a limiter unit that limits the level of an audio signal so as not to exceed the upper limit value, and an upper limit value of the limiter unit are controlled. An upper limit value control unit that calculates the predicted current consumption in the amplifier for each of the plurality of channels, and when the total value exceeds a predetermined value ΣI , the channel with the highest predicted current consumption is prioritized. The upper limit value of the limiter unit is lowered with respect to the channels of the unit, and the total value ΣI of the predicted current consumption is controlled to be a predetermined value or less.
Specifically, the current maximum channel is a channel in which the difference value ΔI between the maximum value and the second largest value among the predicted consumption currents calculated for each of the plurality of channels is detected and the predicted consumption current is the maximum value. When the condition of “ΣI−ΔI × N> predetermined value” is satisfied, the current consumption in the N current maximum channels is the same value as the second largest predicted current consumption. When the upper limit value of the limiter unit for the N current maximum channels is reduced and the condition of “ΣI−ΔI × N> predetermined value” does not hold, the current consumption in the N current maximum channels is “predicted current consumption”. The process of lowering the upper limit value of the limiter unit for the N maximum current channels is calculated for each of the plurality of channels so that the maximum value of (−ΣΣ−predetermined value) / N ”is obtained. The total value ΣI of the predicted current consumption is repeated until it matches a predetermined value.

  According to the present invention configured as described above, the output of all channels is not uniformly attenuated as in the conventional volume control, but the current consumption is limited to only a part of the channels with the larger predicted current consumption. Will be limited. For this reason, the overall change in volume feeling is reduced, and even when current limitation is applied rapidly, it is possible to prevent the output sound from causing a sense of incongruity in hearing. In addition, since the current consumption is quickly limited by the limiter unit before a large current exceeding a predetermined value actually flows, it is possible to reliably avoid the occurrence of a blown fuse.

It is a figure which shows the structural example of the consumption current control apparatus by this embodiment. It is a flowchart which shows the operation example (current consumption control method) of the upper limit control part by this embodiment. It is a figure which shows the example of control of the upper limit value of the limiter part by this embodiment. It is a flowchart which shows the other operation example (current consumption control method) of the upper limit control part by this embodiment. It is a figure which shows the other example of control of the upper limit of the limiter part by this embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a current consumption control device according to the present embodiment. The consumption current control device of this embodiment is for limiting the consumption current in the amplifier corresponding to the multi-channel output so as not to exceed a predetermined value. The limiter unit 12, the voltage detection unit 13, the consumption current prediction unit 21, and An upper limit control unit 22 is provided.

  The limiter unit 12 and the voltage detection unit 13 are configured by a DSP (Digital Signal Processor) 10 together with the audio signal processing unit 11. Further, the current consumption prediction unit 21 and the upper limit value control unit 22 are configured by the CPU 20. The audio signal input to the DSP 10 is subjected to predetermined audio signal processing by the audio signal processing unit 11, and then subjected to output restriction as necessary in the limiter unit 12 and input to the amplifier 30. The audio signal input to the amplifier 30 is amplified according to a gain set according to the volume or the like and output from the speaker 40.

  The limiter unit 12 limits the level of the audio signal so as not to exceed the upper limit value for each of a plurality of channels constituting the multi-channel of the amplifier 30. Specifically, the limiter unit 12 outputs a channel in which the level of the input audio signal does not exceed the upper limit value without applying a level limit to the input audio signal. On the other hand, for a channel in which the level of the input audio signal exceeds the upper limit value, the level of the input audio signal is limited to the upper limit value of the channel and output. The upper limit value of the limiter unit 12 is normally set to a rated value, but is variably set for each of a plurality of channels as will be described later.

  The voltage detector 13 detects the effective voltage value of the audio signal output from the limiter unit 12 for each of a plurality of channels. The consumption current prediction unit 21 corresponds to the voltage value of the audio signal detected by the voltage detection unit 13, the impedance characteristics of the speaker 40 stored in advance in a memory (not shown) such as a RAM as information, the volume, and the like. Based on the set gain of the amplifier 40, the predicted consumption current in the amplifier 30 is calculated for each of a plurality of channels. As a method for calculating the predicted consumption current, for example, the method described in Patent Document 1 can be applied, but the present invention is not limited to this.

  The upper limit control unit 22 determines whether or not the total value of predicted current consumption calculated for each of a plurality of channels by the current consumption prediction unit 21 exceeds a predetermined value. If the total predicted current consumption exceeds a predetermined value, the total predicted current consumption is reduced by lowering the upper limit value of the limiter unit 12 for some channels in preference to the channel with the largest predicted current consumption. Control is performed so that the value is equal to or less than a predetermined value.

  FIG. 2 is a flowchart illustrating an operation example (current consumption control method) of the upper limit control unit 22 according to the present embodiment. FIG. 3 is a conceptual diagram illustrating a control example of the upper limit value of the limiter unit 12 according to the present embodiment. Here, for simplification of explanation, it is assumed that the total number of channels is five. Also, the predicted current consumption of each channel calculated by the current consumption prediction unit 21 is ch1 = 15 [A], ch2 = 6 [A], ch3 = 10 [A], ch4 = 3 [A], ch5 =, respectively. Suppose that it was 4 [A]. In FIG. 3, in order to make the explanation easy to understand, the channels are arranged in descending order of the predicted current consumption.

  In FIG. 2, first, the upper limit control unit 22 determines whether or not the total value ΣI of predicted current consumption calculated for each of a plurality of channels by the current consumption prediction unit 21 exceeds a predetermined value (for example, 30 [A]). Is determined (step S1). In the example of FIG. 3A, the total value ΣI of the predicted current consumption of each channel is 38 [A], so the upper limit control unit 22 determines that it exceeds the predetermined value.

  When it is determined that the total predicted current consumption ΣI exceeds the predetermined value, the upper limit value control unit 22 is the second highest value among the predicted current consumption of each channel calculated by the current consumption prediction unit 21. The difference value ΔI from the large value is detected, and the number N of channels (hereinafter referred to as the maximum value channel number) at which the predicted current consumption becomes the maximum value is detected (step S2). In the example of FIG. 3A, since the maximum value is 15 [A] and the second largest value is 10 [A], the difference value ΔI is 5 [A]. The maximum value channel number N is 1.

Next, the upper limit control unit 22 determines whether or not the following condition (Equation 1) is satisfied (step S3).
ΣI−ΔI × N> 30 [A] (Formula 1)
In the example of FIG. 3A, since the left side = 38 [A] −5 [A] × 1 = 33 [A], the condition of (Expression 1) is satisfied.

  In this case, as shown in FIG. 3 (b), the upper limit control unit 22 has the same value as the predicted consumption current with the second largest consumption current in the channel with the largest predicted consumption current (hereinafter referred to as the maximum current channel). Thus, the upper limit value of the limiter unit 12 for the maximum current channel is lowered (step S4). If the upper limit value of the limiter unit 12 is lowered for the maximum current channel, the audio signal level is limited so that the maximum current channel does not exceed the upper limit value. The current is reduced. The current consumption reduced at this time corresponds to the above-described difference value ΔI. That is, the predicted consumption current in the maximum current channel is reduced by the difference value ΔI.

  This difference value ΔI is a value determined from the amount of change in the voltage value of the audio signal that is restricted by lowering the upper limit value, the impedance characteristics of the speaker 40, and the gain of the amplifier 40 set according to the volume or the like. Therefore, the upper limit control unit 22 calculates the amount of change in the voltage value of the audio signal to be restricted from the difference value ΔI, and the level of the audio signal is decreased by the amount of the voltage value change. The upper limit value of the limiter unit 12 is lowered. Thereafter, the process returns to step S2.

  At the stage of returning from step S4 to step S2, there are two current maximum channels (ch1 and ch3) as shown in FIG. 3B, and the maximum value of the predicted current consumption in these two channels is 10 [A]. It has become. In this case, since the second largest value is 6 [A], the difference value ΔI obtained by the upper limit control unit 22 in step S2 is 4 [A]. The maximum value channel number N is two.

Next, the upper limit control unit 22 determines whether or not the condition of (Expression 1) is satisfied (step S3). In the example of FIG. 3B, since the left side = 33 [A] −4 [A] × 2 = 25 [A], the condition of (Expression 1) is not satisfied. In this case, the upper limit value control unit 22 lowers the upper limit value of the limiter unit 12 for the maximum current channel so that the current consumption in the maximum current channel becomes a value obtained by the following (Equation 2) (step S5). .
Current value of maximum current channel = maximum value of predicted current consumption− (ΣI−30 [A]) / maximum number of channels (Expression 2)

  In the present example, the current value of the maximum current channel = 10 [A] − (33 [A] −30 [A]) / 2 = 8.5 [A], and the channel ch1, as shown in FIG. The upper limit value of the limiter unit 12 for the channels ch1 and ch3 is lowered so that the current consumption in ch3 is 8.5 [A]. Accordingly, the total value ΣI of the predicted consumption currents of all the channels ch1 to ch5 becomes the predetermined value (30 [A]), so the processing of the flowchart shown in FIG.

  In step S1, if it is determined that the total value ΣI of the predicted current consumption of all channels does not exceed the predetermined value (30 [A]), there is no need to lower the upper limit value of the limiter unit 12. However, since there is a possibility that the upper limit value has been reduced to a value smaller than normal by the processing in steps S2 to S5, in order to return to the normal upper limit value, the upper limit values of all channels are temporarily increased to the rated value ( Step S6).

  FIG. 4 is a flowchart showing another operation example (current consumption control method) of the upper limit control unit 22 according to the present embodiment. FIG. 5 is a conceptual diagram illustrating another control example of the upper limit value of the limiter unit 12 according to the present embodiment. Here, the preconditions are the same as those in FIGS. 2 and 3, and the total number of channels is 5 as shown in FIG. 5A, and the predicted current consumption of each channel is ch1 = 15 [A]. Ch2 = 6 [A], ch3 = 10 [A], ch4 = 3 [A], and ch5 = 4 [A].

  In FIG. 4, first, the upper limit control unit 22 determines whether or not the total value ΣI of the predicted consumption current calculated for each of a plurality of channels by the consumption current prediction unit 21 exceeds a predetermined value (for example, 30 [A]). Is determined (step S11). In the example of FIG. 5A, the total value ΣI of the predicted current consumption of each channel is 38 [A], so the upper limit control unit 22 determines that it exceeds the predetermined value.

  When the upper limit control unit 22 determines that the total value ΣI of the predicted current consumption exceeds a predetermined value, the upper limit value control unit 22 has a plurality of values in descending order of the predicted current consumption calculated by the current consumption prediction unit 21. The channels ch1 to ch5 are ranked (step S12). Then, first, k = 1 is designated as the parameter k indicating the order (step S13).

  Next, the upper limit value control unit 22 among the predicted current consumption of each channel calculated by the current consumption prediction unit 21 is the k-th current value and the k + 1-th current value (since initially k = 1, the maximum value). And the second largest value) are detected (step S14). In the example of FIG. 5A, since the maximum value is 15 [A] and the second largest value is 10 [A], the difference value ΔI is 5 [A].

  Furthermore, the upper limit control unit 22 calculates the difference between the total value ΣI of the predicted current consumption and the predetermined value (30 [A]), that is, the excess value of the total value ΣI with respect to the predetermined value (step S15). And the upper limit control part 22 determines whether the difference value (DELTA) I calculated | required by step S14 is below an excess value (step S16). In the example of FIG. 5A, the difference value ΔI is 5 [A] and the excess value is 38 [A] −30 [A] = 8 [A], so the difference value ΔI is equal to or less than the excess value. .

  In this case, as shown in FIG. 5 (b), the upper limit control unit 22 is configured such that the current consumption in the k-th channel (now the first) channel is a value smaller than that by the difference value ΔI. The upper limit value of the limiter unit 12 for the k-th channel is lowered (step S17). In this example, the predicted current consumption of the first channel ch1 is 15 [A] and the difference value ΔI is 5 [A], so that the current consumption in the channel ch1 is 10 [A]. The upper limit value of the limiter unit 12 for the channel ch1 is lowered. Thereafter, the value of the parameter k indicating the rank order of the predicted current consumption is incremented (step S18), and the process returns to step S14.

  At the stage of returning from step S18 to step S14, the upper limit value control unit 22 determines the difference value ΔI between the kth (second) predicted current consumption value and the k + 1th (third) predicted current consumption value. Is detected. In the example of FIG. 5B, the second-ranked predicted current consumption value is 10 [A], and the third-ranked predicted current consumption value is 6 [A]. Therefore, the difference value ΔI is 4 [A]. is there.

  Furthermore, the upper limit control unit 22 calculates an excess value of the predicted current consumption total value ΣI with respect to a predetermined value (step S15). And the upper limit control part 22 determines whether the difference value (DELTA) I calculated | required by step S14 is below an excess value (step S16). In the example of FIG. 5B, the difference value ΔI is 4 [A], and the excess value is 33 [A] −30 [A] = 3 [A], so the difference value ΔI is less than or equal to the excess value. Absent.

  In this case, as shown in FIG. 5 (c), the upper limit control unit 22 causes the current consumption in the k-th (now second) channel to be a value that is smaller than the excess value. The upper limit value of the limiter unit 12 for the k-th channel is lowered (step S19). In the present example, the predicted current consumption of the second channel ch3 is 10 [A] and the excess value is 3 [A], so that the current consumption in the channel ch3 is 7 [A]. The upper limit value of the limiter unit 12 for ch3 is lowered. As a result, the total value ΣI of the predicted current consumption of all the channels ch1 to ch5 becomes the predetermined value (30 [A]), so the processing of the flowchart shown in FIG.

  If it is determined in step S11 that the total value ΣI of the predicted current consumption of all channels does not exceed the predetermined value (30 [A]), it is not necessary to lower the upper limit value of the limiter unit 12. However, since there is a possibility that the upper limit value has been lowered to a value smaller than normal by the processing in steps S12 to S19, in order to return to the normal upper limit value, the upper limit values of all channels are temporarily increased to the rated value ( Step S20).

  As described above in detail, in this embodiment, the limiter unit 12 that limits the level of the audio signal so as not to exceed the upper limit value for each of a plurality of channels constituting the multi-channel of the amplifier 30, and the limiter unit 12 An upper limit control unit 22 that controls the upper limit value and a current consumption prediction unit 21 that calculates the predicted current consumption in the amplifier 30 for each of a plurality of channels, and the total value of the predicted current consumption of all channels exceeds a predetermined value In this case, the upper limit value of the limiter unit 12 is lowered for some channels in preference to the channel with the largest predicted current consumption, and the total value of the predicted current consumption is controlled to be a predetermined value or less.

  According to this embodiment configured as described above, the output of all channels is not uniformly attenuated as in the conventional volume control, but the current consumption is limited to only a part of the channels with the larger predicted current consumption. Will be limited. For this reason, the overall change in volume feeling is reduced. In general, the channel that is in charge of the bass side consumes more current, and the channel on the treble side consumes less current. On the other hand, since the high sound side dominates the volume feeling, even if the upper limit value of the limiter unit 12 is limited so that the current consumption on the low sound side is reduced, the change in the sound volume is not felt by the user. As a result, even if the current is rapidly limited by the limiter unit 12, it is possible to hardly cause a sense of discomfort in the sound output from the speaker 40. In addition, since the current consumption is limited before a large current exceeding the predetermined value actually flows, it is possible to reliably avoid occurrence of a blown fuse.

  Further, according to the present embodiment, the upper limit value of the limiter unit 12 is adjusted so that the rank of each channel related to the magnitude of the predicted current consumption calculated by the current consumption prediction unit 21 does not change. For this reason, there is little change in the overall tone sensation, and it is possible to hardly cause a sense of incongruity about the sound output from the speaker 40.

  In the above embodiment, the limiter unit 12 and the voltage detection unit 13 are configured by the DSP 10, and the current consumption prediction unit 21 and the upper limit control unit 22 are configured by the CPU 20, but the present invention is not limited thereto. Not. For example, you may comprise these structures with a microcomputer, FPGA (Field Programmable Gate Array), etc.

  Moreover, in the said embodiment, although the flowchart of FIG. 2 or FIG. 4 was shown as a procedure which adjusts the upper limit of the limiter part 12, this invention is not limited to this. Any procedure that lowers the upper limit value of the limiter unit 12 for one or more channels (a part of all channels) in preference to the channel with the largest predicted current consumption can be applied instead of FIG. 2 or FIG. is there.

  In the above-described embodiment, the example is described in which the upper limit value of the limiter unit 12 is lowered to control the total current consumption value ΣI of all the channels to be a predetermined value. You may control so that the value (SIGMA) I may become smaller than a predetermined value. For example, in the example of FIGS. 2 and 3, when the condition of (Equation 1) is not satisfied, the upper limit value of the limiter unit 12 is not reduced according to (Equation 2). The upper limit value of the limiter unit 12 may be lowered so that the current consumption in the channel is reduced by the difference value ΔI.

  In this case, the current consumption of the upper three channels ch1, ch3, ch2 is all 6 [A], and the total value ΣI of the current consumption of all channels is 25 [A]. However, this may cause the overall volume to become much smaller than the initial setting, so that the upper limit of the limiter unit 12 is reached until the total value ΣI of all channels is just a predetermined value as in the above embodiment. It is preferable to reduce the value.

  In addition, each of the above-described embodiments is merely an example of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. In other words, the present invention can be implemented in various forms without departing from the spirit or main features thereof.

12 Limiter unit 13 Voltage detection unit 21 Current consumption prediction unit 22 Upper limit control unit 30 Amplifier 40 Speaker

Claims (2)

A current consumption control device for limiting current consumption in a multi-channel output compatible amplifier so as not to exceed a predetermined value,
A limiter unit that limits the level of the audio signal so as not to exceed an upper limit value for each of a plurality of channels constituting the multi-channel;
A current consumption prediction unit that calculates a predicted current consumption in the amplifier for each of the plurality of channels;
When the total value ΣI of the predicted current consumption calculated for each of the plurality of channels by the current consumption prediction unit exceeds the predetermined value, the channel having the highest predicted current consumption has priority over some channels. An upper limit control unit that controls the total value ΣI of the predicted current consumption to be equal to or lower than the predetermined value by lowering the upper limit value of the limiter unit ;
The upper limit value control unit detects a difference value ΔI between the maximum value and the second largest value of the predicted current consumption calculated for each of the plurality of channels by the current consumption prediction unit, and the predicted current consumption is When the number N of the maximum current channels, which are the maximum values, is detected and the condition “ΣI−ΔI × N> predetermined value” is satisfied, the current consumption in the N maximum current channels is the second. When the upper limit value of the limiter unit for the N current maximum channels is lowered so as to be the same value as the large predicted consumption current, while the condition of “ΣI−ΔI × N> predetermined value” is not satisfied. , The current consumption in the N current maximum channels is such that the current consumption in the N current maximum channels is a value obtained by “maximum predicted current consumption− (ΣI−predetermined value) / N”. A current consumption control apparatus that repeats the process of lowering the upper limit value of the limiter unit until a total value ΣI of predicted current consumption calculated for each of the plurality of channels matches the predetermined value . A current consumption control method for limiting current consumption in a multi-channel output compatible amplifier so as not to exceed a predetermined value,
A first step of detecting, for each of the plurality of channels, a voltage value of the audio signal output from a limiter unit that limits the level of the audio signal so as not to exceed an upper limit value for each of a plurality of channels constituting the multi-channel. When,
Based on the voltage value detected in the first step, the impedance characteristics of the speaker stored as information in advance, and the gain of the amplifier, the predicted consumption current in the amplifier is calculated for each of the plurality of channels. A second step;
When the total value ΣI of the predicted current consumption calculated for each of the plurality of channels in the second step exceeds the predetermined value, the channel having the highest predicted current consumption has priority over some channels. A third step of controlling the total value ΣI of the predicted current consumption to be equal to or less than the predetermined value by lowering the upper limit value of the limiter unit ;
In the third step, a difference value ΔI between the maximum value and the second largest value of the predicted current consumption calculated for each of the plurality of channels in the second step is detected, and the predicted current consumption is When the number N of the maximum current channels, which are the maximum values, is detected and the condition “ΣI−ΔI × N> predetermined value” is satisfied, the current consumption in the N maximum current channels is the second. When the upper limit value of the limiter unit for the N current maximum channels is lowered so as to be the same value as the large predicted consumption current, while the condition of “ΣI−ΔI × N> predetermined value” is not satisfied. , The current consumption in the N current maximum channels is such that the current consumption in the N current maximum channels is a value obtained by “maximum predicted current consumption− (ΣI−predetermined value) / N”. A process for reducing the upper limit value of the limiter unit is repeated until a total value ΣI of predicted consumption currents calculated for each of the plurality of channels matches the predetermined value .

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