JP2007036377A - Electronic equipment, and device and method for adjusting acoustic signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electronic equipment, an acoustic signal adjusting device, and an acoustic signal adjustment method that combine analog-like acoustic signal adjustment with digital-like one for adjusting the sound volume of an acoustic input signal, and especially reduce noise generated in switching between analog and digital signals. <P>SOLUTION: In the electronic equipment, the acoustic signal adjusting device, and the acoustic signal adjustment method, gain switching devices 15A, 15B, such as an analog amplifier, are combined with digital gain adjusting devices 19A, 19B, and two different lines of signals are switched alternately for adjusting the volume level of the acoustic signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic apparatus, an acoustic signal adjustment device, and an acoustic signal adjustment method for adjusting the volume of an acoustic input signal by combining analog acoustic signal adjustment and digital acoustic signal adjustment, and more particularly, an analog signal and a digital signal. The present invention relates to an electronic device, an acoustic signal adjustment device, and an acoustic signal adjustment method for reducing noise generated at the time of switching.

  Conventionally, in an electronic device such as an ADC, a DAC, and an input / output signal reproducing apparatus for analog-to-digital conversion (hereinafter referred to as ADC) of analog sound signals or analog-to-digital conversion of digital data (hereinafter referred to as DAC). As a signal level volume adjusting means, a method of adjusting the volume of an acoustic signal in an analog manner with a variable resistor (hereinafter referred to as VR), a VCA (voltage control amplifier), a PGA (programmable gain amplifier) or the like is generally used. Is. In the above-described method of directly adjusting the volume level using the VR, a signal is passed through the VR itself. Therefore, if the audio amplifier board and the VR position are separated from each other, noise may be picked up on the way, and some kind of consideration or countermeasure is required. Is done. In general, the level adjustment method by VAC is not so good in distortion rate and noise level, and those capable of adjusting the distortion rate can be driven to a low distortion rate, but adjustment man-hours are required. Further, the distortion rate, signal level, etc. have temperature characteristics, and if the amount of change is not acceptable, it is necessary to prepare correction means. In the level adjustment method by PGA, even when the gain step for adjustment is small (about 0.5 dB), click noise is heard at the time of gain switching, and a step of about 0.1 dB is required to suppress this. was there.

  Also known is a method for digitally adjusting the input / output data gain level. In the level adjustment method using only digital gain, it is difficult to achieve both maximum allowable input and SN. That is, in order to make it possible to attenuate the signal so as not to be clipped at the maximum allowable input signal, the ADC input may be set to a predetermined level lower than usual so that the ADC input is at the full level at the maximum input signal. When the signal is received at the reference adjustment position, the signal level is reduced by a predetermined amount, so that it is necessary to increase the gain in the digital region, and the noise level increases accordingly. If signal data with the maximum ADC input exceeded is processed to lower the level with digital gain (-digital gain), the signal data will not be displayed even though it is clipped. There is.

  Further, Patent Documents 1 to 3 disclose a technique of a method for performing input / output signal level adjustment by combining analog adjustment and digital adjustment. The technique disclosed in Patent Document 1 shows a method of adjusting to an arbitrary level while adjusting using a rotary knob such as volume adjustment of an audio device to a desired level quickly. That is, it has a VR that adjusts the output volume of an audio signal, a rotation type operation means that can be rotated, and a rotation detection means (rotary encoder) that detects the rotation state of the rotation type operation means. When the first rotation state is detected, the output adjustment at VR is set to the first adjustment mode that changes by the first number of steps, and the second rotation that is rotated at a faster speed than the first rotation state. An input device is provided that includes a control means for setting a second adjustment mode for sequentially changing output adjustment in VR by a second step number that is smaller than the first step number when a state is detected. Yes. The technique disclosed in this document adjusts the volume of the coarse adjustment mode and the fine adjustment mode.

  Patent Document 2 discloses an analog signal processing device that improves the operability by enabling good control over an analog input circuit from a remote location. That is, an input terminal for an analog format input signal, a level designation means for supplying a level designation signal for designating an adjustment level for the input signal away from an operation device installed via a transmission line, and a level designation means First level adjusting means for adjusting the level of the input signal to any one of a plurality of stages by an analog circuit based on the level specified by the supplied level specifying signal, and the level adjusted by the first level adjusting means A digitizing means for converting the input signal into a digital format; and a digital circuit for adjusting the level of the input signal digitized based on the level designated by the level designation signal of the level designation means. Analog having second level adjusting means for performing level adjustment for interpolating between stages adjusted by level adjusting means No. processing apparatus is disclosed. This configuration digitally interpolates the steps adjusted at the analog level.

  Furthermore, Patent Document 3 discloses a volume control device for reducing the troublesomeness of wiring as compared with the analog VR and reducing noise generated when switching the analog gain by providing an analog attenuator after the DAC. Has been. That is, as shown in FIG. 7, this volume variable device includes a digital attenuator 5 provided in a DSP (digital signal processing device) 3 and an analog attenuator 7 provided outside the DSP 3. After the input audio signal is attenuated by the designated attenuation amount, the analog attenuator 7 further attenuates the output by the designated attenuation amount and outputs the result. The attenuation amount control unit 12 in the DSP 3 finely adjusts the volume by controlling the attenuation amount of the digital attenuator 5 based on the volume volume data instructed from the external controller 11. The attenuation amount control unit 12 mainly adjusts the volume by controlling the attenuation amount of the analog attenuator 7 based on the data. The number of control lines 13 that connect the analog attenuator 7 and the attenuation control unit 12 is set according to the number of attenuations that the analog attenuator 7 can set. In FIG. 7, 1 is an input terminal for inputting data, 2 is an ADC, 4 is a signal processing unit, 6 is a DAC, 8 is a main amplifier, 9 is a speaker, and 10 is a key input unit.

Patent Document 3 discloses a volume changing device that uses a combination of analog gain and digital gain similar to those of the present invention in conjunction with the latter stage of ADC 2. In this open technology, noise generated when the analog gain is switched is unavoidable. Therefore, when the attenuation control means designates the attenuation amount to the digital attenuator or the analog attenuator, the attenuation amount is sent to the analog attenuator or the digital attenuator. The first delay means or the second delay means for delaying from the timing for designating is provided. Therefore, if the time from the indication of the amount of attenuation of the analog attenuator or the digital attenuator to the change of the volume is longer than that of the digital attenuator or the analog attenuator, both attenuators are In the output, the volume can be changed at the same time, so that the noise caused by the difference in volume change between the two attenuators is reduced, so that it is necessary to provide first and second delay means.
JP 2002-101485 A JP 2000-278050 A JP 09-153748 A

  The present invention has been made to solve the above-mentioned problems, and the problem to be solved by the present invention is to reduce the noise at the time of switching when the combination of the analog gain adjusting means and the digital gain adjusting means is used in conjunction. In order to do this, prepare two combinations of analog gain adjustment means and digital gain adjustment means, and set each switching position to occur alternately. Level adjustment signal data while avoiding noise that occurs during analog gain switching Thus, an electronic device, an acoustic signal adjustment device, and an acoustic signal adjustment method capable of reducing noise can be obtained.

  An electronic apparatus according to a first aspect of the present invention is an electronic apparatus in which the gain level of an analog sound signal can be adjusted via an analog gain level adjustment unit and a digital gain level adjustment unit. First and second analog gain level switching means that can be switched, and first and second analog-digital conversion means that are supplied with the outputs of the first and second analog gain level switching means and digitized, First and second digital gain level adjusting means for adjusting the digital gain level of the analog sound signal digitized by the first and second analog-digital converting means, and first and second digital gain level adjusting means Data switching means for alternately outputting outputs from the analog gain level disposed in the first and second paths. It is obtained form to reduce the noise generated when switching by the switching means and the digital gain level adjusting means and control means for controlling the data switching means.

  According to a second aspect of the present invention, there is provided an acoustic signal adjusting device comprising: an acoustic signal adjusting device capable of adjusting an analog acoustic signal gain level via an analog gain level adjusting unit and a digital gain level adjusting unit; First and second analog / digital analog signals which are supplied with outputs of first and second analog gain level switching means and first and second analog gain level switching means which can be switched to a plurality of gains. Conversion means, first and second digital gain level adjustment means for adjusting the digital gain level of the analog sound signal digitized by the first and second analog-digital conversion means, and first and second digital Data switching means for alternately outputting the output from the gain level adjusting means, and an analog circuit arranged on the first and second paths. It is obtained by the way to reduce the noise generated when switching the grayed gain level switching means and the digital gain level adjusting means and control means for controlling the data switching means.

  An acoustic signal adjustment method according to a third aspect of the present invention is an acoustic signal adjustment method in which the gain level of an analog acoustic signal can be adjusted via an analog gain level adjustment means and a digital gain level adjustment means. A step of switching to a plurality of gains by the first and second analog gain level switching means, and a first and second analog-digital conversion means to which the outputs of the first and second analog gain level switching means are supplied. A step of digitizing, a step of adjusting a digital gain level of the analog sound signal digitized by the first and second analog-to-digital conversion means by a first and second digital gain level adjusting means, And a step of alternately outputting the output from the second digital gain level adjusting means by the data switching means. And a step of switching to a plurality of gains of the analog gain level switching means arranged in the first and second paths, an adjustment step of the digital gain level adjusting means, and a step of alternately outputting by the data switching means The noise generated at the time of switching is reduced by controlling by the control means.

  According to the present invention, it is possible to achieve both a large maximum allowable input and a low noise volume adjustment, and there is no click even if the volume adjustment level of the sound input signal is continuously changed from the maximum to the minimum (-∞). Can be changed. In addition, it is possible to provide an electronic device, an acoustic signal adjustment device, and an acoustic signal adjustment method that do not require the use of an element with inferior noise performance or an element that requires distortion adjustment.

  An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an overall system diagram illustrating an embodiment of an electronic device, an acoustic signal adjustment device, and an acoustic signal adjustment method according to the present invention. FIG. 2 is an electronic device, an acoustic signal adjustment device, and an acoustic signal adjustment method according to the present invention. FIG. 3 is a graph of one embodiment showing the relationship between the analog gain and the digital gain and the positional relationship when the analog gain is switched between the two paths, and FIG. 3 shows one of the electronic apparatus, the acoustic signal adjusting device, and the acoustic signal adjusting method of the present invention. FIG. 4 is a flowchart of one embodiment showing a gain control method for the other B path of the electronic apparatus, the acoustic signal adjusting device, and the acoustic signal adjusting method of the present invention. 5 is a flowchart of one embodiment showing a gain control method at the time of switching two paths of the electronic apparatus, the acoustic signal adjustment device, and the acoustic signal adjustment method of the present invention, and FIG. The gain of each part when the volume is adjusted by the electronic apparatus, the acoustic signal adjustment device, and the acoustic signal adjustment method of the present invention ("gain" used below means + "= so-called gain" and-"= attenuation") It is a table | surface which shows.

  FIG. 1 shows an overall block of the electronic apparatus and the acoustic signal adjustment device 50 according to the present invention. In FIG. 1, an acoustic signal AS such as an analog audio signal of one system supplied to an input terminal 14 is supplied to two gain switchers 15A and a gain switcher 15B such as an analog amplifier having a plurality of gain switching functions. The For example, as shown in Table 1 of FIG. 6, these have 8 stages of gain in 4 dB steps, the gain switch 15A switches between +18 dB and −10 dB, and the gain switch 15B switches between +20 and −8 dB. An analog switch can be used to switch the analog gain in eight steps.

  Thereafter, the analog sound signal AS is converted into digital data by the ADC 16A and ADC 16B dedicated to the two paths. The digital data converted by the ADCs 16A and 16B is finely adjusted within a range of 0 to +0.5 dB by two, for example, digital gain correctors 18A and 18B in the programmable logic device (hereinafter referred to as PLD) 17, for example, −1 dB to The digital gain adjusters 19A and 19B in the +3 dB range (4 dB width) are input. Thereafter, the data switched by the gain switching units 15A and 15B is cross-fade through each path (hereinafter referred to as A path and B path), and the data switching unit is switched to either the A path or the B path. After switching to 20 and finally obtaining acoustic digital data ADD such as digital audio data having a required volume adjusted, it is supplied to the next signal processing means 21 such as a recording / reproducing processing circuit. The digital processing of the digital gain correctors 18A and 18B, the digital gain adjusters 19A and 19B, and the cross-fade data switching unit 20 and a control unit 33 described later are processed in one PLD 17.

  In the above-described configuration, the gain switching unit 15A and the gain switching unit 15B may be any elements as long as they can have different gains required, and may be the same. For example, the gain switch 15A and the gain switch 15B can be used if a functional element having a number of steps equal to or greater than the required number of steps and an appropriate gain value can be selected for each path of the A path and the B path. The same functional element may be used.

  The gain switching units 15A and 15B have a step number and step amount ranging from +18 dB to -10 dB for the gain switching unit 15A and +20 to -8 dB for the gain switching unit 15B. Although described as 4 dB, this is an example, and it is natural to change it as necessary. In this case, if the step amount is reduced, the + digital gain increase amount required becomes smaller and the increase in noise level can be reduced, but the gain corresponding range in the analog portion becomes narrower. On the contrary, if the step amount is increased, the gain corresponding range in the analog portion is widened, but the + digital gain increase amount is also increased, and the noise level is increased accordingly. To achieve both, it is necessary to increase the number of steps. Note that the step amount of each step does not have to be the same value in each stage, but it is necessary to perform control according to it.

  The actual gain value of each path of the gain switchers 15A and 15B composed of analog amplifiers needs to be accurately matched with a target gain value (total cane) described later, but the resistance value is limited. It is conceivable that the target value is slightly deviated because the number of resistors cannot be increased. In such a case, the digital gain correctors 18A and 18B that are integrated into the IC by the PLD 17 described above correct the subtraction of the actual gain value from the target gain values of the A path and B path of the gain switchers 15A and 15B. However, the digital gain correctors 18A and 18B can be omitted if the error of the gain values of the A path and the B path can be made sufficiently small.

  Further, as the gain difference between the gain switching unit 15A and the gain switching unit 15B, a case has been described in which the gain values of the A path and B system path gain switching units 15A and 15B are alternately set in a single direction at intervals of 2 dB. The gain switching unit 15A has a switching step of −10, −6, −3, +1, +5 dB, etc., and the gain switching unit 15B has a switching step of − It is obvious that non-uniform intervals such as 9, −5, −2, +4, +9 dB,. Furthermore, the gain balance between the A path and the B path may be lost due to the sensitivity difference between the ADCs 16A and 16B. In this case, the sensitivity difference is corrected in an analog manner using a semi-fixed VR or the like, or the sensitivity difference is reduced. The correction may be performed by the digital correctors 18A and 18B. In this case, since the correction value is different for each substrate, it is necessary to store the correction value in a non-volatile memory (see FIG. 1) 32 described below. is there.

  The correction by the digital gain correctors 16A and 16B here is usually used to correct the sensitivity difference between the ADCs 16A and 16B, but a small gain error between the stages of the gain switchers 15A and 15B is corrected and controlled according to each stage. You may do it together. For example, when the gain changers 15A and 15B are discretely assembled, it is conceivable that a small variation occurs in the step amount of each step due to the restriction of the resistance value of the resistor to be used. However, if the number of resistors is increased, it can be accurately adjusted. Although the number of resistors is not increased, the minute gain error may be corrected (in conjunction with the correction of the sensitivity difference between the ADCs 16A and 16B). In any case, since the purpose is to correct the variation, the digital gain correctors 18A and 18B may not be provided if the variation does not cause a problem.

  In addition, the gains of the digital gain adjusters 19A and 19B are controlled by taking into account the correction amount performed by the digital gain correctors 18A and 18B. It can be realized with one functional element by operation.

  The starting points of operation of the data selectors 20 for the A path and the B path are all 0 dB, but may be any value within 0 dB within the normal variable range (-1 to +3 dB in the above), and when the volume adjustment amount increases and decreases Different values may be used. However, as the value is increased, the amount of noise deterioration increases.

  The above-described crossfade processing is mainly intended to relieve small clicks that occur during the actual A path and B path switching operations. Therefore, if the clicks are sufficiently small even if the crossfade processing is not performed in the circuit that is actually used, It is not necessary to provide a cross fade processing unit. In the above description, the gain difference between the digital gain adjuster 19A and the digital gain adjuster 19B, the total gain value of the A path and the B path are always 2 dB (= half of the step amount), and the total gain always match. If the total gains of the A path and the B system path coincide with each other only during the cross fade period of the data switcher 20 of the path A and the path B (= the total gain may be inconsistent except during the cross fade period). Good.

  Next, the configuration of the control method of the volume adjustment amount (in this example, the total gain value is +22 dB to −∞ as shown in Table 1 of FIG. 6) will be described with reference to FIG. The panel or chassis of the front panel substrate 24 is provided with an audio signal VR knob 23 and supplied with a menu operation signal MS. The knob 22 is fixed to the rotating shaft of the analog VR 25 and is manually rotatable. By rotating the knob 23, position information (DC) from the VR 25 is supplied to the ADC 26, converted into digital data, then supplied to the front panel microcomputer 28, and 0 to 100 corresponding to the position of the VR 24 at the output terminal 29. % VR position information PD which is digital data is output.

  In response to the operation of the menu button 27, the menu operation signal MS is supplied to the front panel microcomputer 28 and output to the output terminal 30. For example, the headroom setting value (20/18/16/12 dB, default 20 dB) HS for the headroom by the setting of the menu button 27 is basically supplied to the main microcomputer 31 that only handles transmission. A nonvolatile memory 32 is added to the main microcomputer 31 as necessary, and VR position information PD, headroom setting value HS, correction values for each substrate for correcting the above-described sensitivity difference by the digital correctors 18A and 18B, and the like. Store. The VR position information PD and the headroom set value HS from the main microcomputer 28 are supplied to the control unit 33 in the PLD 17.

  The control unit 33 of the PLD 17 determines a target total gain value from the VR position information PD and the headroom setting value HS. In this case, the gain difference between the headroom setting value HS set by the menu button 27 and the default value is reflected in the total gain value. The control unit 33 performs gain control 34 and gain control 35 for the A path on the gain switch 15A side and B path on the gain switch 15B side, and selection (switching) control 36 for the A path and B path.

  The A path gain control 34 controls the A path gain switch 15A, the A path digital gain corrector 18A, and the A path digital gain adjuster 19A. The B path gain control 35 controls the B path gain switch 15B. The B path digital gain compensator 18B and the B path digital gain adjuster 19B are controlled, and the A path and B path selection control 36 controls the data switching unit 20.

  In this example, the A path gain control 34 and the B path gain control 35 are set so that the total gain of each circuit of the A path and the total gain of each circuit of the B path are always equal to the target total gain value. The gain control 35 and 36 for the A path and the B path is performed from the A path to the B path or B when the total gain value generated when the two gain switchers 15A and 15B for the A path and B path are switched and gain values other than the vicinity thereof. Switching from the route to the A route occurs.

  Hereinafter, the volume control operation of the electronic device and the acoustic signal adjustment device having the above-described configurations will be described in detail. In the electronic device 50 of the present invention, at least two paths of A path and B path in which an analog circuit and a digital circuit are combined are prepared for one acoustic signal AS, and the volume of the acoustic signal AS is adjusted by a gain switch composed of an analog amplifier. 15A and 15B and the gain adjustment of the digital gain adjusters 19A and 19B. In this case, the analog gain switching is in charge of a large step change, and the digital gain adjustment is usually in charge of a small change portion less than that step (when other than a special operation described later).

  The graph of FIG. 2 shows the relationship between the analog gain and the digital gain and the positional relationship between the switching noise generated when the gain switching units 15A and 15B are switched and the data switching unit 20. The horizontal axis in FIG. PD, the vertical axis represents the total gain value (dB), the straight line 37 indicates the total gain of the A path, the straight line 38 indicates the total gain of the B path, and A1, A2, A3, A4, A5 , A6 are for analog gain, D1, D2, D3. D4, D5, and D6 indicate digital gain assignments. In FIG. 2, the straight line 37 of the A path and the straight line 38 of the B path have the same gain value, but the total gain values are separated from each other for convenience of explanation of the operation.

  When the volume adjustment position (for example, corresponding to the rotation angle of VR25) is changed from the lowermost position to the uppermost position, the switching positions of the two A / B paths by the data switching device 20 appear alternately and at different positions. Set. The data output unit 20 switches the data from the A path to the B path or from the B path to the A path by the broken line arrow position in FIG. To supply.

  In the present invention, the total gain obtained by adding the analog gain and the digital gain in the above-described A system path and B path is set to always have the same value in both system paths. When the analog gain is switched in one system path and the switching noise 39 is generated, the digital data in the other system (the switching noise 39 is not generated because the analog gain switching has not occurred) is always selected and controlled.

  Further, the data switching by the data switching unit 20 is not instantaneously performed, but the crossfade operation is controlled so that the data is gradually replaced. That is, with respect to the data of each route of A and B, the gain of one A route is gradually decreased with time in the direction of 100% → 0%, and the gain of the other B route is 0% → 100% direction. The control is gradually increased with time. At this time, the change between 100% and 0% starts and ends at the same time for both the A route and the B route. By adding the data of both A and B paths, digital data in which the data is gradually replaced is obtained. Such a crossfade operation is not stopped until the data is completely changed once it is started.

  The volume adjustment VR25 position information PD stops updating at the start of the cross-fade operation, and reflects the change in the VR position information PD after the completion (if necessary) after the stop. During the crossfade operation, control is performed so that the gains of the digital gain adjusters 19A and 19B do not become less than 0 dB.

  When the digital gain is less than 0 dB, if the gain switch 15A, 15B requires a gain that exceeds the upper / lower limit range, the analog gain is limited to the upper / lower limit value, and the digital gain adjustment is made for the shortage. This is not used as the final output data in this example except during special operations that are distributed to the devices 19A and 19B. The reason for this is that the data with the maximum input of the ADCs 16A and 16B is reduced by digital gain. This is because the signal data is not clipped even though it is clipped.

  The smaller side of the minimum analog gain values of the A path and the B system path is set to a value that does not clip at the ADCs 16A and 16B at the maximum allowable input and until the digital data corresponding to the analog signal is output from the ADCs 16A and 16B. Since it takes a certain time inherent to the ADCs 16A and 16B, control values (= gain values to be given to the digital gain correctors 18A and 18B, gain values to be given to the digital gain adjusters 19A and 19B, and the data switching unit 20) Is preferably supplied via delay means for delaying the control value given to the gain changers 15A and 15B by a fixed time inherent to the ADCs 16A and 16B. The reason is as follows. When the delay correction is correct, the digital gain step portion is processed for the data for which the analog gain switching has been performed, so that the click portion existing on the data stream can be regarded as almost one place. However, when the delay correction is not performed or the delay correction amount is not appropriate, there are two clicks, ie, the click of the analog gain switching portion and the click of the digital gain step portion. On the other hand, A / B data switching is set to occur at a total gain value different from the total gain value at which a large gain level difference occurs. Therefore, when the VR 25 is rotated slowly, the two cannot be considered to interfere with each other. However, when delay correction is not performed correctly, if the time difference described above is large and the VR 25 is rotated quickly, one of the two clicks may interfere with the A / B data switching timing. Then, we are concerned about the occurrence of new clicks. Therefore, it is desirable to perform digital data processing using timing information suitable for the data. This time difference correction is not required to be accurate enough to drive to the ultimate zero, and may be performed as long as it is corrected to such an extent that a new click does not occur when the VR 25 is quickly turned. In some cases, the two interferences may not occur without any correction. (For example, when the upper limit is set for the rotation speed of VR25)

  In the system diagram described with reference to FIG. 1, the gain switching units 15A and 15B constituting the analog amplifier each have 8 stages of gain in 4 dB steps, the gain switching unit 15A is +18 dB to −10 dB, and the gain switching unit 15B is +20 to − The range of 8 dB is switched, the digital gain correctors 18A and 18B perform fine adjustment correction in the range of 0 to +0.5 dB, respectively, and the digital gain adjusters 19A and 19Bd have a minimum step in the range of −1 dB to +3 dB which is 4 dB wide. In the data switching unit 20 of the A path and the B path, the specific control method when the cross fading operation is performed is basically controlled under the following conditions.

(A) The gain value of the gain switch 15A of the analog amplifier configuration and the gain value of the gain switch 15B are controlled so as to always have a difference of 2 dB. (See Figure 6)
(B) The gain value of the digital gain adjuster 19A and the gain value of the digital gain adjuster 19B are controlled so as to always be a 2 dB difference that complements the analog gain difference. (See Figure 6)
(C) The total gain value of the A path obtained by adding the gain value of the gain switch 15A and the gain value of the digital gain adjuster 19A and the total gain value of the B path are controlled to be always the same. (See Figure 6)

(D) When the volume adjustment is varied in the increasing direction by the control of the data switcher (gain is in the range of -1 dB to +3 dB) for switching the A path and the B system path, the data switching from the A path to the B path is performed. This is performed when the gain of the digital gain adjuster 19B reaches 0 dB from the negative value. (Substantially + minute value) Data switching from the B path to the A path is performed when the gain of the digital gain adjuster 19A reaches 0 dB from the-value. (Substantially + minute value) (see FIG. 6)
(E) When the volume adjustment is varied in the downward direction by the control of the data switching unit (gain is in the range of -1 dB to +3 dB) for switching the A route and the B system route, the data switching from the A route to the B route is performed. This is performed when the gain of the digital gain adjuster 19A reaches 0 dB from the + value. (Substantially + minute value) Data switching from the B path to the A path is performed when the gain of the digital gain adjuster 19B reaches 0 dB from the + value. (Substantially + minute value) (see FIG. 6)

(F) The gains of the digital gain correctors 18A and 18B and the digital gain adjusters 19A and 19B are basically controlled so as not to be less than 0 dB, but the gain on the system side when the final output is not used at all is It may be less than 0 dB. (Control is performed so that both systems do not become less than 0 dB during the crossfade period)
(G) Stop updating the volume adjustment position information at the same time or immediately before the start of the crossfade. The position information is updated continuously after the stop (if necessary) after the completion of the crossfade. This is because the next switching operation of the gain switch 15A or 16B is prevented during the crossfade operation. This is to prevent data having a digital gain less than 0 dB from being used for crossfading when crossfading starts when the volume adjustment is varied in the downward direction.

  In the crossfade operation, depending on the actual circuit, a slight DC offset change may occur during the switching operation of the gain switchers 15A and 15B. There is usually a DC cut capacitor immediately before the ADCs 16A and 16B, and since the ADCs 16A and 16B are equipped with HPFs, their offset components disappear with time. Since the gain switchers 15A and 16B of the analog amplifier configuration and the gain switchers 19A and 19B of the A path and the B path are set at different volume adjustment positions, when the volume is adjusted slowly, at the time of switching between the A path and the B path. However, when the volume is adjusted quickly, there may be some DC fluctuation components remaining. If the A path and the B path are instantaneously switched in this state, the DC step component can be heard as a click sound. Therefore, a softening click sound can be obtained by performing a cross-fade operation and smoothing the change amount of switching. Further, an effect of relieving a click component generated when there is a slight gain difference between the A system path and the B system path due to the cross-fade operation is also obtained.

  Hereinafter, the specific control method described above will be described in detail with reference to FIGS. 3 is a flowchart showing the gain determination algorithm of each circuit of the A path in FIG. 1, FIG. 4 is a flowchart showing the gain determination algorithm of each circuit of the B path in FIG. 1, and FIG. 2 is a flowchart showing a switching selection determination algorithm of the data switcher of the A route and the B route in FIG.

  3 and 6, in the first step S1, a total gain value as a target value is determined based on the menu button 27. In the second step S2, it is determined whether or not the target value of the total gain value is “−∞ or more and less than −7 dB”. If “YES”, the process proceeds to the third step S3. Proceeding to step S6, in the third step S3, the gain switch 15A selects a gain value of −10 dB. As the actual actual value in the third step S3, a value that is smaller by “a1 dB” corresponding to the design error is output. In the fourth step S4, the digital gain corrector 18A is corrected by setting the gain value “a1 dB”, and in the fifth step S5, the gain value of the target value “− (− 10 dB)” is set in the digital gain adjuster 19A. After the end of the fifth step S5, the end (S25) is reached.

  In the sixth step S6, it is determined whether or not the target value is “−7 dB or more and less than −3 dB”. If “YES”, the process proceeds to the seventh step S7, and if “NO”, the process proceeds to the tenth step S10. In the seventh step S7, the gain switch 15A selects a gain value of −6 dB. As the actual actual value in the seventh step S7, a value smaller by “a2 dB” corresponding to the design error is output. In the eighth step S8, the digital gain corrector 18A is corrected by setting the gain value “a2 dB”, and in the ninth step S9, the digital gain adjuster 19A is set with the target value “− (− 6 dB)”. After the ninth step S9 ends, the end (S25) is reached.

  In the tenth step S10, it is determined whether or not the target value is “−3 dB or more and less than +1 dB”. If “YES”, the process proceeds to the eleventh step S11. If “NO”, the target value in FIG. The process proceeds to the next determination step of “Is +1 dB or more and less than +5 dB” and “Is +5 dB or more and less than +9 dB?”, But the subsequent steps are omitted for the same repetition. In an eleventh step S11, the gain switch 15A selects a gain value of -2 dB. The actual value in the eleventh step S11 is a value that is smaller by “a3 dB” corresponding to the design error. In the twelfth step S12, the digital gain corrector 18A is corrected by setting the gain value “a3 dB”, and in the thirteenth step S13, the digital gain adjuster 19A is set with the target value “− (− 20 dB)”. After the thirteenth step S13, the end (S25) is reached.

  The process proceeds from the “NO” state after determination omitted during the determination step of “+1 dB or more to less than +5 dB” or “+5 dB or more to less than +9 dB” to the 14th step S14. In this step, the target value is “less than +9 dB + 13 dB”. If “YES”, the process proceeds to the 15th step S15. If “NO”, the process proceeds to the 18th step S18. In the 15th step S15, the gain switch 15A selects a gain value of +10 dB. To do. As the actual actual value in the fifteenth step S15, a value smaller by “a6 dB” corresponding to the design error is output. In the sixteenth step S16, correction is performed by setting the gain value “a6B” in the digital gain corrector 18A, and in the seventeenth step S17, the gain value of the target value “− (+ 10 dB)” is set in the digital gain adjuster 19A. After the end of the 17th step S17, the process reaches the end (S25).

  In the 18th step S18, it is determined whether or not the target value is “+13 dB or more and less than +17 dB”. If “YES”, the process proceeds to the 19th step S19, and if “NO”, the process proceeds to the 22nd step S22. In a nineteenth step S19, a gain value of +14 dB is selected by the gain switch 15A. The actual value in the nineteenth step S19 is a value that is smaller by “a7 dB” corresponding to the design error. In the 20th step S20, the digital gain corrector 18A is corrected by setting the gain value “a7 dB”, and in the 21st step S21, the gain value of the target value “− (+ 14 dB)” is set in the digital gain adjuster 19A. After the end of the 21st step S21, the end (S25) is reached.

  If the 18th step S18 is “NO”, the process proceeds to the 22nd step S22. In the 22nd step S22, a gain value of +18 dB is selected by the analog gain switch 15A. As the actual actual value in the 22nd step S22, a value smaller by “a8 dB” corresponding to the design error is output. In the 23rd step S23, the digital gain corrector 18A is corrected by setting the gain value “a8 dB”, and in the 24th step S24, the gain value of the target value “− (+ 18 dB)” is set in the digital gain adjuster 19A. After the end of the ninth step S9, the end (S25) is reached.

  Next, an algorithm for determining the gain of each circuit in the B path will be described with reference to FIGS. In FIG. 4, in the first step ST <b> 1, a total gain value as a target value is determined based on the menu button 27. In the second step ST2, it is determined whether or not the target value of the total gain value is “−∞ or more and less than −5 dB”. If “YES”, the process proceeds to the third step ST3. Proceeding to step ST6, in the third step ST3, the gain switch 15B selects a gain value of −8 dB. As the actual actual value in the third step ST3, a value smaller by “b1 dB” corresponding to the design error is output. In the fourth step ST4, the digital gain corrector 18B is corrected by setting the gain value “b1 dB”, and in the fifth step ST5, the gain value of the target value “− (− 8 dB)” is set in the digital gain adjuster 19B. After the end of the fifth step ST5, the end (ST25) is reached.

  In the sixth step ST6, it is determined whether or not the target value is “−5 dB or more and less than −1 dB”. If “YES”, the process proceeds to the seventh step ST7, and if “NO”, the process proceeds to the tenth step ST10. In the proceeding seventh step ST7, a gain value of −4 dB is selected by the gain switch 15B. As the actual actual value in the seventh step ST7, a value smaller by “b2 dB” corresponding to the design error is output. In the eighth step ST8, the digital gain corrector 18B is corrected by setting the gain value “b2 dB”, and in the ninth step ST9, the digital gain adjuster 19B is set with the target value “− (− 4 dB)”. After the ninth step ST9, the end (ST25) is reached.

  In the tenth step ST10, it is determined whether or not the target value is “-1 dB or more and less than +3 dB”. If “YES”, the process proceeds to the eleventh step ST11. If “NO”, the process proceeds to FIG. The process proceeds to the next determination step of “Is −1 dB or more and less than +3 dB”, “Is +3 dB or more and less than +7 dB”, and “+7 dB or more and less than +11 dB”, but the subsequent steps are omitted for the same repetition. In the eleventh step ST11, the gain switch 15B selects a gain value of 0 dB. The actual actual value of the eleventh step ST11 is a value that is smaller by “b3 dB” corresponding to the design error. In the twelfth step ST12, the digital gain corrector 18B is corrected by setting the gain value “b3 dB”, and in the thirteenth step ST13, the digital gain adjuster 19B is set with the target value “− (0 dB)”. After the end of the thirteenth step ST13, the end (ST25) is reached.

  The process proceeds to the 14th step ST14 from the “NO” state after the determination that is omitted in the middle of the determination steps of “−1 dB or more and less than +3 dB”, “+3 dB or more and less than +7 dB”, and “+7 dB or more and less than 11 dB”. Is “less than +11 dB + 15 dB”. If “YES”, the process proceeds to the fifteenth step ST15. If “NO”, the process proceeds to the eighteenth step ST18. In the fifteenth step ST15, the gain switch 15B To select a gain value of +12 dB. As the actual actual value in the fifteenth step ST15, a value smaller by “b6 dB” corresponding to the design error is output. In the 16th step ST16, the digital gain corrector 18B is corrected by setting the gain value “b6B”. In the 17th step ST17, the digital gain adjuster 19B is set with the target value “− (+ 12 dB)”. After the end of the 17th step ST17, the end (ST25) is reached.

  In the 18th step ST18, it is determined whether or not the target value is “+15 dB or more and less than +19 dB”. If “YES”, the process proceeds to the 19th step ST19, and if “NO”, the process proceeds to the 22nd step ST22. In the nineteenth step ST19, a gain value of +16 dB is selected by the gain switch 15B. As the actual actual value in the nineteenth step ST19, a value smaller by “b7 dB” corresponding to the design error is output. In the 20th step ST20, the digital gain corrector 18B is corrected by setting the gain value “b7 dB”, and in the 21st step ST21, the gain value of the target value “− (+ 16 dB)” is set in the digital gain adjuster 19B. After the end of the 21st step ST21, the end (ST25) is reached.

  If the 18th step ST18 is “NO”, the process proceeds to the 22nd step ST22. In the 22nd step ST22, a gain value of +20 dB is selected by the analog gain switch 15B. The actual actual value of the 22nd step ST22 is a value that is smaller by “b8 dB” corresponding to the design error. In the 23rd step ST23, the digital gain corrector 18B is corrected by setting the gain value “b8 dB”, and in the 24th step ST24, the gain value of the target value “− (+ 20 dB)” is set in the digital gain adjuster 19B. After the end of the ninth step ST9, the end (ST25) is reached.

  Next, the switching selection determination algorithm of the data selector 20 for the A route and the B route will be described with reference to the flowchart shown in FIG. In FIG. 5, the first step STE1 is a start to determine a new target total gain value, and in the second step STE2, it is determined whether or not the target value is “−∞ or more and less than −8 dB”. If "YES" is performed, the process proceeds to the third step SET3, where the data selector 20 for the A path and the B path selects the signal for the A path and reaches the end (STE 13). In the case of “NO”, whether or not the target value is “−8 dB or more and less than −6 dB” is determined by the fourth step STE4. If “YES”, the process proceeds to the fifth step STP5, and the route A and The data selector 20 for the B path selects the signal for the B path and reaches the end (STE 13).

  In the second step STE2, whether or not the target value is “−∞ or more and less than −8 dB” is determined “YES”, the process proceeds to the third step SET3. The signal of the A path is selected and the end (STE 13) is reached. In the case of “NO”, whether or not the target value is “−8 dB or more and less than −6 dB” is determined by the fourth step STE4. If “YES”, the process proceeds to the fifth step STP5, and the route A and The data selector 20 for the B path selects the signal for the B path and reaches the end (STE 13).

  In the sixth step STE6, it is determined whether or not the target value is “−6 dB or more and less than −4 dB”. If “YES”, the process proceeds to the seventh step SET7. The signal of the A path is selected and the end (STE 13) is reached. In the case of “NO”, the same operation is repeated and is omitted in the middle, but whether or not the target value is “168 dB or more and less than 18 dB” is determined by the eighth step STE8. Proceeding to the ninth step STP9, the data switcher 20 for the A path and the B path selects the signal for the B path and reaches the end (STE 13).

  If the eighth step STE8 is “NO”, the process proceeds to the tenth step STE10. In the tenth step STE10, it is determined whether or not the target value is “+18 dB or more and less than +20 dB”. 11 In step SET11, the data switcher 20 for the A route and the B route selects the signal for the A route and reaches the end (STE 13). In the case of “NO”, in the twelfth step STE12, the data switcher 20 for the A route and the B route selects the signal for the B route and reaches the end (STE13).

  The case where the gain switchers 15A and 15B configured by analog amplifiers and the digital gain adjustment units 19A and 19B operate specially with the above configuration will be described. The gain switching units 15A and 15B have analog gains exceeding the upper limit / lower limit. If a value is required, the analog gain is limited to the upper limit / lower limit value, and the shortage is distributed to the digital gain adjusters 19A and 19B. Table 1 shows the gain value of each part in the case of the setting of FIG. The shaded portions of the analog gain switchers 15A and 15B and the digital gain adjusters 19A and 19B correspond to the special operation area. If the total gain is made smaller than the lower limit, no particular problem arises. However, if the total gain is exceeded, the + digital gain increase amount is increased, so that the noise level is deteriorated. Therefore, it is desirable to minimize the special operation in the part exceeding the upper limit. The total gain A and B path columns indicate the side used after switching between the A path and the B path.

  In the data switching between the gain switching units 15A and 15B and A / B, if the A / B path switching is performed alternately without any trouble when the volume adjustment VR25 is moved up and down, the hysteresis is set with respect to the setting of these positions. When the volume adjustment VR25 is raised as an operation, after passing through the switching position of the A / B data switching device 20, the switching position and the switching position of the gain switching devices 15A and 15B are moved slightly downward, and then lowered. It may be set so that after passing through the switching position of the A / B path data switching unit 20, the switching position is moved slightly upward. If the volume adjustment position information is in the vicinity of the switching point and there is a slight fluctuation in the actual position information, the switching operation will be repeated (= may be heard as noise). It can suppress by the effect of.

  In the above-described electronic device, acoustic signal adjustment device, and acoustic signal adjustment method, the front panel microcomputer 28, the main microcomputer 31, and the A / B path control and the A / B data switch 33 of the control unit 33 in the PLD are configured separately. However, these units are integrated into the main microcomputer, and the functional units 15A, 15B, 16A, 16B, 18A, 18B, 19a, 19B, 20, 26, 28, 31, 32, Some or all of the 33 functions can also be stored in one IC.

  According to the present invention, a large maximum allowable input and low noise can be achieved at the same time, and even if the volume adjustment level of the sound input signal is continuously changed from the maximum to the minimum (−∞), the click can be smoothly changed. Can do. In addition, it is possible to provide an electronic device, an acoustic signal adjustment device, and an acoustic signal adjustment method that do not require the use of an element with inferior noise performance or an element that requires distortion adjustment. When other level switching functions other than continuous volume adjustment are required in the analog signal path (for example, reference input level selection, headroom selection, etc.), the gain variable range of the present invention including the gain change amount of that function By designing and controlling the circuit, the circuit scale can be reduced by incorporating them.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram showing one embodiment of an electronic apparatus, an acoustic signal adjustment device, and an acoustic signal adjustment method of the present invention. It is a graph of one form example which shows the relationship between the analog gain and digital gain of the electronic device of this invention, an acoustic signal adjustment device, and an acoustic signal adjustment method, and the positional relationship at the time of A / B path | route switching. It is a flowchart of 1 form which shows the gain control method of the A path | route of the electronic device of this invention, an acoustic signal adjustment apparatus, and an acoustic signal adjustment method. It is a flowchart of one example which shows the gain control method of B path | route of the electronic device of this invention, an acoustic signal adjustment apparatus, and an acoustic signal adjustment method. It is a flowchart of one example which shows the gain control method of the A / B switching path | route of the electronic device of this invention, an acoustic signal adjustment apparatus, and an acoustic signal adjustment method. It is a table | surface which shows the gain of each part when the sound volume adjustment of the electronic device of this invention, an acoustic signal adjustment apparatus, and an acoustic signal adjustment method is performed. It is a systematic diagram of the conventional volume control apparatus.

Explanation of symbols

14 ... Input terminal, 15A, 15B ... Gain switch, 16A, 16B, 26 ... ADC, 17 ... PLD, 18A, 18B ... Digital gain corrector, 19A, 19B ... Digital gain adjuster, 20 ... Data switch, 23 ... Audio signal knob, 24 ... Front panel board, 25 ... VR, 26 ... Front panel microcomputer, 27 ... Menu button , 31 ... main microcomputer, 33 ... control unit, 34 ... path gain control unit, 35 ... B path gain controller, 36 ... A / B path selection control unit

Claims (3)

In an electronic device in which the gain level of an analog sound signal can be adjusted via an analog gain level adjusting means and a digital gain level adjusting means.
First and second analog gain level switching means capable of switching the analog acoustic signal to a plurality of gains;
First and second analog-to-digital conversion means that are supplied with outputs of the first and second analog gain level switching means and digitized;
First and second digital gain level adjusting means for adjusting a digital gain level of the analog sound signal digitized by the first and second analog-digital converting means;
Data switching means for alternately outputting outputs from the first and second digital gain level adjusting means,
An electronic device characterized in that noise generated at the time of switching is reduced by a control means for controlling the analog gain level switching means, the digital gain level adjusting means, and the data switching means arranged on the first and second paths. machine. In an acoustic signal adjustment device capable of adjusting the gain level of an analog acoustic signal via an analog gain level adjustment means and a digital gain level adjustment means,
First and second analog gain level switching means capable of switching the analog acoustic signal to a plurality of gains;
First and second analog-to-digital conversion means that are supplied with outputs of the first and second analog gain level switching means and digitized;
First and second digital gain level adjusting means for adjusting a digital gain level of the analog acoustic signal digitized by the first and second analog-digital converting means;
Data switching means for alternately outputting outputs from the first and second digital gain level adjusting means,
Noise generated at the time of switching is reduced by analog gain level switching means, digital gain level adjustment means, and control means for controlling data switching means arranged on the first and second paths. Signal conditioning device. In an acoustic signal adjustment method, the gain level of an analog acoustic signal can be adjusted via an analog gain level adjustment means and a digital gain level adjustment means.
Switching the analog acoustic signal to a plurality of gains by first and second analog gain level switching means;
Digitizing by first and second analog-to-digital conversion means supplied with outputs of the first and second analog gain level switching means;
Adjusting the digital gain level of the analog sound signal digitized by the first and second analog-digital conversion means by the first and second digital gain level adjusting means;
Alternately outputting the output from the first and second digital gain level adjusting means by the data switching means,
The control means controls the step of switching to a plurality of gains of the analog gain level switching means arranged in the first and second paths, the adjustment step of the digital gain level adjusting means, and the step of alternately outputting by the data switching means. An acoustic signal adjustment method characterized in that noise generated at the time of switching is reduced.

Images