JP2000216647A - Level display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a level display device where the degree of the level change in a level display corresponding to each region denoting high/low audio signal sound volume levels is improved. SOLUTION: The level display device displays levels from a minimum sound volume level to a maximum level where they are divided into a plurality of stages of levels, and the display device has a display characteristic curve combining 1st curves C1, C3, C5 that pass through a 1st point P1 decided at a predetermined level between the maximum and minimum stages of the level display of a plurality of stages and at a predetermined sound volume level between the minimum and maximum sound volume levels, a 2nd point P2 at the level of the level display at the maximum stage decided by the sound volume maximum level and the maximum stage level, and whose rate of change is gradually increased from the 1st point P1 toward the 2nd point P2, with 2nd curves C2, C4, C6 that passes through the 1st point P1 and a 3rd point P3 at the level of the level display of a minimum stage decided by a sound volume minimum level and a lowest stage level and whose rate of change is gradually increased from the 1st point P1 toward the 3rd point P3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio signal level display device.

[0002]

2. Description of the Related Art A conventional level display device displays a level corresponding to a digital value obtained by A / D (analog / digital) conversion of an audio signal by a microcomputer, for example, on a level display unit, for example, a bar level display. The bar level is displayed by supplying it to the unit. Such a bar level display device includes a type in which the entire band level of an audio signal is displayed on one bar level display unit, and a method in which an audio signal is divided into a plurality of bands by a band pass filter (BPF) circuit, and There is a spectrum analyzer type that displays levels on a plurality of different bar level display units.

FIGS. 5 and 6 are graphs showing typical examples of display characteristics of a conventional bar-level display device. FIG.
In the graph of FIG. 6, the horizontal axis represents the volume level of the audio signal, and the vertical axis represents the bar level display divided into, for example, 11 bar levels with respect to the maximum (maximum) level of the volume.

In the example of FIG. 5, the change of the bar level display is as follows.
It is proportional to the change in volume level, and the display characteristics are represented by straight lines. In the example of FIG. 6, the change in the bar level display is logarithmically proportional to the change in the volume level, and the display characteristic is represented by a logarithmic function curve.

FIG. 7 also shows that the applicant previously invented,
7 is a graph showing display characteristics of a bar level display device disclosed as Japanese Patent Application Laid-Open No. 7-199822. In this example,
The logarithmic function curves L1 and L2, which are different for each area of levels 1 to 6 and levels 6 to 11, are displayed with a point approximately half the maximum volume level as a boundary. Thereby, the display area in the saturated state is reduced as compared with the characteristics of the bar level display shown in FIG.

[0006]

However, the conventional method of reading the sound volume level as shown in FIGS. 5 to 7, that is, the bar level display corresponding to the method of converting the sound volume level to the bar level by a microcomputer or the like, is not used. ,
The bar level display still tends to clutter above the bar level at loud sounds, i.e. at loud volume levels. Further, in the bar level display shown in FIGS. 5 and 7, at a low sound level, that is, at a low volume level, the bar level is below the bar level and is difficult to swing. Therefore, the display above and below the bar level display has little change and is hard to see.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a level display device which improves the level change level of a level display corresponding to an area where the volume level of an audio signal is high or low.

[0008]

In view of the above-mentioned object,
The level display device of the present invention is a level display device for displaying a volume level of an audio signal on a level display section divided into a plurality of levels from a minimum volume level to a maximum volume level. A first point determined by the level of the predetermined level between the highest level and the lowest level of the plurality of levels, and a maximum level of the volume and the highest level. A first curve passing through a second point representing the height of the highest level display determined by the level, the rate of change of which gradually increases from the first point to the second point; and a first point. And a third point representing the height of the lowest level display determined by the lowest volume level and the lowest level, and the rate of change is from the first point. And a display characteristic curve of a combination of a second curve gradually increases to 3 points.
Thereby, the degree of the level change of the level display corresponding to the region where the volume level of the audio signal is large and the region where the volume level is small becomes large as compared with the level change of the level display corresponding to the predetermined volume level, so that it is easy to see. Become.

According to another aspect of the present invention, in addition to the above-described level display device of the present invention, the first curve and the second curve include the first curve.
Have different rates of change at the same distance from the point. As a result, the level display changes in an area where the volume level is high and an area where the volume level is low, to different degrees, and the level display can be easily viewed according to the signal that tends to be biased toward the higher or lower volume level.

According to another aspect of the invention, in addition to the level display device of the above-described aspect, the first point is determined by a volume level which is の of the maximum volume level and an intermediate level of a plurality of levels. I have. As a result, the degree of change in the level display becomes well-balanced at the zero volume level and the maximum level of the volume, and the level display near the middle between them has no sharp change in the level display and becomes well-balanced. .

In another aspect of the present invention, in addition to the level display device of the above-described aspect, the first point is changed according to the type of the audio signal. This makes it possible to perform level display that is easy to see in accordance with the type of audio signal.

According to another aspect of the invention, in addition to the level display devices of the above-described inventions, the first curve and the second curve each have an n (2 ≦ n ≦ 8) -th order whose origin is the first point. It is a function curve. As a result, the degree of change of the level display gradually increases from the volume level near the middle of the zero volume level and the maximum volume level to the zero volume level and the maximum volume level, and the balance is easy to see.

Further, in another invention, in addition to the level display device of the above-described invention, the first curve and the second curve are changed according to the type of the audio signal. This makes it possible to perform easy-to-see level display according to the type of audio signal.

In another aspect of the invention, in addition to the level display device of the above-described aspect, the type of the audio signal is determined based on a code representing the type of the signal recorded on the recording medium. Thereby, the degree of level display can be automatically changed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a level display device according to the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing an example of an embodiment of a bar level display device as a level display device according to the present invention. In FIG. 1, the bar level display device 1 is shown as being incorporated in, for example, a car audio set. The car audio set includes a bar level display device 1 and an electronic volume circuit 2, but omits other components not directly related to the description of the present invention.

The bar level display device 1 comprises a mixing circuit 3, an auto gain circuit 4, a BPF (band pass filter) circuit 5, a microcomputer 6, and a bar level display 7.
It is composed of The electronic volume circuit 2 includes an input selector 8, a volume circuit 9, and a fader circuit 10. The bar level display 7 is of a spectrum analyzer type having a plurality of bar level display units. Each bar level display section has a plurality of levels, for example, 11 levels, and lights up sequentially from the first level to the highest level (ie, the eleventh level) according to the input signal level. By doing so, bar level display is performed.

Audio signals from various input sources input to the electronic volume circuit 2, for example, a CD (compact disk) reproduction signal, a tuner reception signal (AM)
Broadcast reception signal, FM broadcast reception signal, etc.) and AUX
The (auxiliary input) signal is selected by the input selector 8. The selected audio signal is supplied to the volume circuit 9 as L and R stereo signals. Volume circuit 9
Performs volume control, loudness control, bass range control, treble range control, midrange control, and the like.

The L and R stereo signals from the volume circuit 9 are converted by the fader circuit 10 into four-channel signals, ie, a front left channel, a front right channel, a rear left channel and a rear right channel signal. The four-channel signal from the fader circuit 10 is transmitted to each speaker, for example, a front left speaker, a front right speaker, a rear left speaker, and a rear right speaker, which are respectively disposed on the front left, front right, rear left, and rear right in the automobile. (Not shown).

On the other hand, the L and R stereo signals from the input selector 8 are mixed in the mixing circuit 3 of the bar level display device 1 by resistance mixing or the like and supplied to the auto gain circuit 4. When the maximum levels of the audio signals from the various input sources are different (for example, when the maximum level of the tuner reception signal is higher than the maximum level of the CD reproduction signal), the auto gain circuit 4 outputs the signals from all the input sources. The maximum level of the audio signal is adjusted to be constant, for example, 5 volts.

The audio signal whose level has been adjusted by the auto gain circuit 4 is supplied to a BPF circuit 5. The BPF circuit 5 converts the audio signal from the auto gain circuit 4 into a plurality of bands, for example, 40 Hz, 100 Hz, 500 H
The signals are divided into five bands centered on z, 1 kHz and 5 kHz and supplied to each A / D port of the microcomputer 6. The audio signal for each band supplied to the A / D port is A / D converted and supplied to the bar level display 7 as digital data. The bar level indicator 7
The digital data of the audio signal for each band is displayed on the corresponding bar level display section.

When the microcomputer 6 supplies the A / D-converted digital data to the bar-level display 7, the microcomputer 6 processes the display characteristics so that the display characteristics are as shown in the graph of FIG. In the graph of FIG. 2, the horizontal axis represents the volume level of the audio signal, that is, the input level of the A / D port of the microcomputer 6 (in this example, the maximum level is 5 volts), and the vertical axis represents the bar of 11 steps. The bar level display divided into levels is shown.

The microcomputer 6 first determines a predetermined volume level, for example, １ ／ of the maximum volume level.
The point P1 in FIG. 2 is set to a predetermined volume level between the minimum volume level and the maximum volume level and the maximum of the bar levels in a plurality of levels by performing processing so that the bar level 6 starts to be lit at the volume level of. It is set as a first point determined at a bar level of a predetermined stage between the stage and the lowest stage. Then, the microcomputer 6 starts from the first point P1, the maximum volume level and the highest bar level, that is, the first level.
With respect to the change of the volume level up to the second point P2 representing the height of the highest level bar level display determined by the one level bar level, the bar levels 6 to 11 show the quadratic function curve C
1 so as to be sequentially turned on. In addition, the microcomputer 6 starts from the first point P1, the lowest volume level and the lowest bar level, that is, the first level.
The lighting of the bar levels 6-1 follows the quadratic function curve C2 with respect to the change in the volume level up to the third point P3 representing the height of the lowest bar level display determined by the bar level of the second step. Process as follows. Therefore, the positive 2
The quadratic function curve C1 and the negative quadratic function curve C2 are combined at a first point P1 to form an overall bar level display characteristic curve.

As a result, when the volume level of the audio signal is near the first point P1 (for example, in FIG. 2, near the volume level of １ ／ of the maximum volume level), the bar level with respect to the change of the volume level The display change rate is small. Therefore, near bar level 6, the degree of change in lighting of the bar level is small.

On the other hand, as the volume level of the audio signal changes from the first point P1 to the second point P2, ie, toward the maximum volume level, the rate of change of the bar level display with respect to the volume level change gradually increases. ing. Therefore, from bar level 6 to bar level 11, the degree of change in lighting of the bar level gradually increases. Therefore, in the vicinity of the bar level 11 at the highest stage, the degree of change in lighting is the largest, and the bar is easy to see.

Similarly, the volume level of the audio signal is
As the position changes from the first point P1 to the third point P3, the rate of change of the bar level display with respect to the change of the volume level gradually increases. Therefore, from bar level 6 to bar level 1, the degree of change in lighting of the bar level gradually increases. Therefore, in the vicinity of the bar level 1 at the lowest stage, the degree of change in lighting is the largest, and the lighting is easy to see.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications and applications are possible. For example, in the above-described embodiment, the bar level display section of the bar level display 7 has 11 levels, but may have any number of levels.

The microcomputer 6 is not dedicated to the bar level display device 1, but is a microcomputer (not shown) for controlling the entire car audio set.
May also be used.

The auto gain circuit 4 can be omitted, and if omitted, the microcomputer 6
Performs processing to compensate for differences in maximum levels of audio signals from various input sources to be input for bar level display.

The first point P1 determined by the predetermined volume level and the bar level at the predetermined stage is a volume level that is 1/2 of the maximum volume level and a bar at an intermediate stage of a plurality of stages. Although the level is determined by the level, the level may be determined by an arbitrary volume level and an optional bar level. Although P1, P2, and P3 use the display start point of each bar level, other positions such as an intermediate point or an end point of each bar level may be used.

Although a quadratic function curve is used,
Any n-order function curve where n is 2 or more and 8 or less may be used. For example, in FIG. 2, cubic function curves C3 and C4 can be used, or quartic function curves C5 and C6 can be used. At this time, as the value of n increases, the swing of the bar level increases at the first point P1.
Near the second point P2 and the third point
At the point P3. Therefore, the value of n is selected according to the content of the audio signal so that the bar level has an appropriate swing that prevents the bar level from swinging too much or from swinging too much. Therefore, the value of n is desirably 8 or less. At this time, the value of n is preferably an integer, but need not be an integer.

A curve (first curve) between the first point P1 and the second point P2 and a first point P1
The curve (second curve) between the first point and the third point P3 is the first point.
Curves having the same rate of change at a position separated by the same distance from the point P1 may be combined, or curves having different rates of change may be combined.

In another invention, the first point, the first curve, and the second curve may be changed according to the type of the audio signal. For example, it can be changed depending on the genre of music (rock, pop, classical, etc.) to be listened to in CD playback.

For example, in the case of rock music, since there are many loud sounds, as shown in FIG.
Is used as a higher-order function curve having a large value of n, here, the fourth-order function curves C5 and C6. As a result, in a region where the volume level is high, the fluctuation of the bar level display can be improved even if the volume level is slightly changed, that is, even if the input level to the A / D port is slightly changed.

In the case of classical music, as shown in FIG. 4, the first curve is a curve having a small n value, here a quadratic function curve C1, and the second curve is a curve having an n value. A large curve, here a quartic function curve C6, is used. This makes it possible to improve the swing of the bar level display even in a low volume level area, even in a low volume level area, in a well-defined music such as classical music. Swings neatly. Further, an n-order function curve in which n is a number greater than 1 and equal to or less than 2 may be used. Note that the first curve and the second curve that are changed according to the audio signal are n-th order (2 ≦ n).
≦ 8) Not limited to a function curve. Further, the first curve and the second curve may be a composite curve composed of a plurality of n-order functions.

Also, the type of the input audio signal,
For example, a program for the microcomputer 6 may be provided so that the combination of curves can be freely changed manually using operation keys or switches according to the genre of music. This makes it possible to set a bar level display characteristic curve according to the user's preference.

Further, as another invention, the microcomputer 6 determines the type of the input audio signal, the genre of the music, for example, based on the code representing the type of the signal recorded on the recording medium. You may comprise. Such a code can be recorded as, for example, TOC data of a CD disk. The microcomputer 6 automatically selects the first point and the type of curve according to the code, and automatically creates an optimal bar-level characteristic curve.

[0038]

According to the present invention, it is possible to improve the degree of the level change of the level display corresponding to the region where the volume level of the audio signal is large or small.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an embodiment of a bar level display device as a level display device according to the present invention.

FIG. 2 is a graph showing an example of display characteristics of the bar level display device of FIG.

FIG. 3 is a graph showing another example of display characteristics of the bar level display device of FIG.

FIG. 4 is a graph showing still another example of the display characteristics of the bar level display device of FIG.

FIG. 5 is a graph showing an example of display characteristics of a conventional bar level display device.

FIG. 6 is a graph showing another example of display characteristics of a conventional bar level display device.

FIG. 7 is a graph showing an example of display characteristics of a conventional bar-level display device previously invented by the present applicant.

[Explanation of symbols]

 Reference Signs List 1 bar level display device 2 electronic volume circuit 3 mixing circuit 4 auto gain circuit 5 BPF (band pass filter) circuit 6 microcomputer 7 bar level display 8 input selector 9 volume circuit 10 fader circuit

Claims (7)

[Claims] 1. A level display device for displaying a volume level of an audio signal on a level display section divided into a plurality of levels from a minimum volume level to a maximum volume level,
A first volume level determined between the minimum volume level and the maximum volume level, and a predetermined level between the highest level and the lowest level of the plurality of levels. A second point indicating the height of the highest level display determined by the volume maximum level and the highest level, and the rate of change from the first point to the second point. A first curve that is progressively larger, the first point,
It passes through the third point indicating the height of the lowest level display determined by the lowest volume level and the lowest level, and the rate of change gradually increases from the first point to the third point. A level display device having a display characteristic curve obtained by combining a second curve and a second curve. 2. The level according to claim 1, wherein the first curve and the second curve have different rates of change at the same distance from the first point. Display device. 3. The level display according to claim 1, wherein the first point is determined by a volume level that is の of the maximum volume level and a level at an intermediate stage of the plurality of stages. apparatus. 4. The level display device according to claim 1, wherein the first point is changed according to a type of the audio signal. 5. The first curve and the second curve each have n (2 ≦ 2) with the first point as an origin.
n ≦ 8) It is a quadratic function curve.
5. The level display device according to 2, 3, or 4. 6. The level display device according to claim 1, wherein the first curve and the second curve are changed according to the type of the audio signal. . 7. The level display device according to claim 4, wherein the type of the audio signal is determined based on a code representing the type of the signal recorded on a recording medium.