JPH0419724B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graphic equalizer suitable for in-vehicle audio equipment such as car stereos.

Car audio equipment that integrates an AM/FM radio, tape recorder, etc. is known as a car stereo, and has become an almost indispensable accessory in the modern automobile civilization.

In addition, the demand for high-fidelity audio equipment extends to car stereos, and as devices with superior acoustic characteristics come into use, it is becoming more and more important to correct the acoustic characteristics in cars and adjust the frequency characteristics by programming. Correction also requires careful consideration, which is why car stereos are now being equipped with graphic equalizers.

This graphical equalizer (hereinafter referred to as GEQ) divides the frequency band of an audio signal into multiple frequency bands, or channels, and changes the level characteristics for each channel, making it possible to arbitrarily change the frequency characteristics across all bands. Generally, a combination of a simulated inductor using an operational amplifier and a bridge amplifier is used, and this GEQ
The above requirements can be met by providing this in a car stereo.

By the way, this GEQ is equipped with a large number of variable resistors or switches for adjustment, corresponding to the channels mentioned above, so operating them requires considerable skill, and even then, it is quite cumbersome and troublesome. It has become a very simple operation.

Therefore, having to repeatedly operate the GEQ when changing a program not only places a considerable psychological burden on the user, but also poses a risk to the safety of automobile operation, especially when used as an in-vehicle device such as a car stereo. There was a risk that it would turn out to be something extremely unpleasant.

Therefore, in order to solve such problems,
You can give any frequency characteristic by simply setting data corresponding to the various frequency characteristics you are trying to obtain with GEQ in memory, etc., and selecting one of the preset data when necessary. A so-called presettable GEQ is known.

According to this presettable GEQ (hereinafter referred to as PGEQ), it can be installed in car stereos, etc., and can be easily and safely operated to provide the necessary equalization characteristics, so it can be used as an audio device equipped with GEQ. It can fully demonstrate its functions and is fully capable of achieving higher performance and luxury in car stereos, etc.

However, on the other hand, such conventional PGEQ
In this case, the equalization characteristics are given by the control data read from the memory, so
Unlike a normal GEQ, it is not possible to immediately know what kind of frequency characteristics are currently given from the position of the operation keys on the operation panel.

Therefore, a display device capable of two-dimensional display was installed,
A PGEQ has been proposed in which the control data supplied to the signal transmission circuit is input to this display device so that it can be recognized as a characteristic curve display in a plane. It is possible to immediately recognize what kind of frequency characteristics are currently being provided, regardless of the position of the operation keys on the operation panel surface, further enhancing the luxury feel of car stereos and the like.

By the way, if the equalization characteristics are preset using control data stored in such memory means, the control data will be lost each time the power is turned off, and the preset operation will have to be performed each time the power is turned on. must be repeated,
There were problems in that the operation was complicated and the sense of luxury was significantly impaired.

It is an object of the present invention to eliminate the drawbacks of the prior art described above, and to provide a system that does not require any extra operations even when the power is turned on, and is free from particularly unpleasant equalization characteristics, so that it is always comfortable. Our goal is to provide a PGEQ that allows you to perform the following functions.

To achieve this objective, the present invention provides that whenever the power is turned on, the equalization characteristics that were set when the power was last turned off are automatically preset, and The present invention is characterized in that standard equalization characteristics are automatically preset when there is an abnormality in the control data.

Embodiments of the equalizer device according to the present invention will be described below with reference to the drawings.

Figure 1 shows an embodiment in which the present invention is controlled by a microcomputer.
In the GEQ section, 2 is a control section, and 3 is a level detection section.

In the GEQ section 1, 10 and 11 are R channel and L channel audio signal input terminals, 12
is a bridge amplifier, 13 is an analog switch, 1
4 is a simulated inductor, 15 is a mute circuit, and 16 and 17 are R channel and L channel audio signal output terminals.

In the control unit 2, 20 is a microcomputer, 21 is a central processor unit (CPU), and 22
is a read-only memory (ROM) for storing programs, 23 is a random access memory (RAM), 24 is an input/output device (I/O), and 25 is a
The PGEQ operation panel has a switch section, 26 is a display section of the operation panel, and 27 is a data latch.

Note that the level detection section 3 will be described later.

Next, the operation will be explained.

Bridge amplifier 12 constitutes the signal transmission circuit of GEQ, has independent signal transmission circuits for R channel and L channel signals, and is coupled to simulated inductor 14 by analog switch 13 to transmit audio signals. The entire band is divided into a large number of frequency channels, for example, five types of channels, and the amount of signal passing through each channel is controlled according to the switching state of the analog switch 13, so that arbitrary frequency characteristics can be given. .

The mute circuit 15 is provided to eliminate transient changes in the audio signal output that occur when the analog switch 13 is switched and the equalization characteristic provided by the bridge amplifier 12 changes in a stepwise manner.

Therefore, the audio signals supplied from the input terminals 10 and 11 are subjected to predetermined equalization processing according to the switching state of the analog switch 13, and then supplied to the output terminals 16 and 17, thereby operating as a GEQ.

Next, the operation of supplying control data A to the analog switch 13 will be explained.

The switch section 25 of the operation panel is configured as shown in FIG. 2, for example, with slide encoders 25a to 25e, memory keys 25f, and memory keys 25g to 2
5k is a preset key, and 25l is an f special/level key.

The slide encoders 25a to 25e are for adjusting the amount of attenuation or gain for each of the five frequency channels, and are designed to generate nine types of control data in 4 bits according to the slide position. The control data is made to correspond to the output level.

Memory key 25f is slide encoder 25
This is a switch used when storing control data representing the output level for each frequency channel set by a to 25e at a predetermined address in the RAM 23 of the microcomputer 20. And since the data to be memorized at this time requires an output level of 4 bits for every 5 channels,
The total is 20 bits.

The preset keys 25g to 25k specify addresses in the RAM 23, read control data from those addresses, and also
When f is pressed, control data set by the slide encoders 25a to 25e is written to the corresponding address in the RAM 23.

The f special/level key 25l is used to switch display contents, and will be described in detail later. Note that all of these keys 25f to 25l are of the so-called touch switch type.

The display unit 26 is a matrix display 2 shown in FIG.
6a and indicator lights 26f to 26l provided in each key 25f to 25l, among which,
The matrix display 26a is a display capable of two-dimensional display in which (5×9) dot-shaped display elements 26a(1) are arranged in a matrix.

The data latch 27 is the I/O 24 of the microcomputer 20.
It holds the data written via the analog switch 13 and the mute circuit 13.

The RAM 23 of the microcomputer 20 is provided with the following four types of memory areas.

(1) Current data memory A memory that stores control data that will be output in accordance with the current operating position of the slide encoders 25a to 25g.

(2) Output data memory Memory that stores the control data currently being output to the data latch.

(3) 5 corresponding to preset keys 25g to 25k
A memory in which different types of independent control data are stored.

(4) Display output memory A memory that stores display data for the matrix display 26a and each of the indicator lights 26f to 26l.

Therefore, now slide encoders 25a to 2
5e, the contents of the current data memory are rewritten accordingly. At this time, if neither the memory key 25f nor the preset keys 25g to 25k are operated, the contents of the current data memory are directly transferred to the output data memory. will be given to

As a result, these slide encoders 25a
25e, the control data from them is directly applied to the analog switch 13 via the data latch 27, so that the equalization characteristics for the audio signal can be directly controlled as desired.

Also, at this time, the contents of the output data memory are given to the display output memory, so that the display element 26a(1) of the display 26a displays the attenuation amount (or gain) for each frequency channel as shown in FIG. ), one display element lights up to display the currently given frequency characteristics.

Next, when the memory key 25f is pressed in this state, the indicator light 26f lights up for about 5 seconds, indicating that memory is possible.

So, following this, preset key 25g~
When any one of the keys 25k is pressed, any one of the indicator lights 26g to 26k corresponding to the pressed key lights up, and the current memory contents are written into the corresponding preset memory. At the same time, the indicator light 26f of the memory key 25f goes out.
Indicates that memory is no longer available. In addition, after pressing memory key 25f,
If the preset keys 25g to 25k are not pressed within seconds, the indicator light 26f goes out. In addition, these preset keys 25
The indicator lights 26g to 26k of g to 25k do not light up at the same time, and the preset keys 25g to 25k
When two or more keys are pressed at the same time, only the indicator light of the last pressed key lights up.

In this way, when one of the preset keys 25g to 25k is pressed and one of the corresponding indicator lights 26g to 26k lights up, the contents of the preset memory corresponding to that key are read out and written to the output data memory. Therefore, at this time, the analog switch 13 is controlled by the control data written in this preset memory, and the corresponding equalization characteristic is given to the audio signal.

At the same time, the contents of the display output memory are also rewritten with the contents of the output data memory, so at this time, the preset keys 25g to 25
The equalization characteristic given by k will be displayed on the display 26a.

On the other hand, when the indicator light 26f of the memory key 25f is not lit, that is, without pressing this key,
Or, if you press any of the preset keys 25g to 25k more than 5 seconds after pressing the key,
Regardless of the status of the slide encoders 25a to 25e, that is, the current contents of the data memory, the contents of the corresponding preset memory are given as they are to the output data memory, and at this time, the control data stored in advance,
That is, the analog switch 13 is controlled by the preset data, a corresponding equalization characteristic is given, and this is displayed on the display 26a. For writing these preset data, please use slide encoder 2.
The operations possible by operating the memory keys 5a to 25e, the memory keys 25f, and the corresponding preset keys 25g to 25k have already been described.

Furthermore, when the indicator light 26g to 26k of any one of the preset keys 25g to 25k is lit, that is, when the equalization characteristic is set by the preset data, any one of the slide encoders 25a to 25e is turned on. If even one of them is operated, the control state based on the preset data is reset, the contents of the current data memory are written to the output data memory, and the slide encoders 25a to 25e are used to give an arbitrary frequency characteristic. This means that adjustments can be made.

The above operations are all performed by the microcontroller 20.
It is executed by a program written in the ROM, and the CPU of the microcontroller 20
21 takes in and sends input data between the switch section 25, display section 26, and data latch 27 via the I/O 24 according to a predetermined procedure;
Furthermore, it performs necessary processing by writing data to and reading data from the RAM 23.

Therefore, according to this embodiment, the frequency characteristics of the GEQ installed in a car stereo or the like can be arbitrarily adjusted using the slide encoders 25a to 25e, and the frequency characteristics of the preset 5 In addition to being able to select any type of equalization characteristic with a single touch of the preset keys 25f to 25k, the matrix display 26a shows what kind of frequency characteristic is currently being given to the audio signal. Since the display is as shown in FIG. 3, the operating status can be fully grasped at all times.

By the way, in the above embodiment, the level detection section 3 is provided, and thereby the matrix display 2
GEQ the output audio signal level by 6a.
Each channel can be displayed independently.

Therefore, this point will be explained below.

In FIG. 1, 30 is an adder circuit, 31 is a preamplifier, 32 is an analog switch, 33 is a simulated inductor, and 34 is an analog-digital converter (A/D).

The adder circuit 30 combines the R channel and L channel audio signals obtained from the output of the bridge amplifier 12 into one channel signal, and supplies the signal to the input of the bridge amplifier 31.

bridge amplifier 31, analog switch 32,
The simulated inductor 33 may be the same as the preamplifier 12, the analog switch 13, and the simulated inductor 14, respectively, and when the analog switch 32 is controlled by control data B from the data latch 27 of the control section 2,
It operates as five types of bandpass filters whose passbands are the frequency bands of each GEQ channel.As shown in FIG. 4, the contact 32a of the analog switch 32 is are sequentially and almost periodically switched, and one of the inductors 33a to 33e of the simulated inductor 33 is selectively switched and connected to the bridge amplifier 31. As a result, the inductor 33a is connected to the bridge amplifier 31. At this time, only the mainly 60Hz component signal of the audio signal IN is taken out to the output L _A , and when the inductor 33b is connected, mainly the 250Hz component signal is taken out to the output L A.
The component of , and 1kHz in inductor 33c,
3.5kHz for inductor 33d, inductor 33e
In this case, each 10kHz will be taken out to the output L _A.

Therefore, an analog signal representing the level of each channel of the audio signal from the adder circuit 30 appears repeatedly and periodically on the output _LA .

The A/D 34 receives the analog signal of the output L _A and converts it into 4-bit digital level data L _D.

Therefore, when you press the f special/level key 25l provided on the switch section 25 of the operation panel, the signal from this key 25l is read by the microcomputer 20 via the I/O 24, and the indicator light in the display memory is first read. The content corresponding to 26l has been rewritten and the indicator light 26l lights up, indicating that the display mode of the display 26a has changed from the previous frequency characteristic display mode (the display mode shown in Figure 3) to the level display mode. indicate. At the same time, f special/level key 2
The display operation program is switched by the input from 5l, and the microcomputer 20 switches the data latch 2.
7 to control data B to the analog switch 32.
The audio signals of each channel are sequentially input to the A/D 34, and the resulting digital level data L _D is written into the display output data memory of the RAM 23.

As a result, the display elements 26a(1) corresponding to each channel of the matrix display 26a light up sequentially from the bottom in the form of a bar graph, the number of which corresponds to the level of the audio signal of that channel, and each channel is illuminated as shown in FIG. It works so that each level is displayed dynamically.

Therefore, according to this embodiment, f
By operating the special/level key 25l, the output level for each frequency band of the audio signal can be displayed, allowing you to understand the operating status of your car stereo from multiple angles, giving you an excellent usability. .

In the above embodiment, when the f special/level key 25l is pressed first, the indicator light 26l lights up to enter the level display mode, and then the indicator light 26l is turned on.
If you press the button when the indicator light 26l is lit, the indicator light 26l will disappear and the mode will switch to the frequency characteristic display mode, but when you press the memory key 25f or any of the preset keys 25g to 25k, Thereafter, the mode is automatically changed to the frequency characteristic display mode for about 5 seconds, and during that time, input by the f-key/level key 25l may not be accepted. According to this, when writing new control data to the preset memory and when setting the GEQ equalization characteristics using preset control data, you can always visually check the frequency characteristics, and avoid mistakes. It is possible to prevent such characteristics from being given.

By the way, it goes without saying that devices using such microcomputers require initialization to start the program operation from a predetermined operation every time the power is turned on.
If the memory contents of RAM 23 are random, the equalization characteristics given when pressing preset keys 25g to 25k will be random, and unpleasant sounds may be played from the car stereo etc. when the power switch is turned on. occurs.

Furthermore, if the preset data disappears every time the power is turned off, the memory operation must be repeated each time, which is cumbersome.

Therefore, in the above embodiment, the RAM 23 is powered by a battery or the like, so that the data in the RAM 23 is saved regardless of whether the car stereo or the like is turned on or off. If the preset keys 25g to 25k are turned on, preset data is immediately given, and necessary equalization characteristics can be given with one touch while checking on the display 26a.

In addition, in the above embodiment, the state of the preset keys 25g to 25k is checked immediately before the power is turned off by using the power backup method of the RAM 23.
Store it in the specified memory area of RMA23,
The next time the power switch is turned on, this RAM2 will be used as a program during the initialization operation.
The contents of the predetermined memory area of No. 3 are determined so that the operating state of the PGEQ at the first time after the power is turned on is the same as the state when the power was turned off.

This allows the slide encoders 25a to 25e to display the state immediately before the power is turned off.
When the GEQ's equalization characteristics have been applied, that is, when the contents of the current data memory have been read out to the output data memory, operation will start in that state the next time the power is turned on, and the If the indicator light of one of the preset keys 25g to 25k is lit when the switch is turned off, and the equalization characteristic is given by the contents of the corresponding preset memory, the next time the power is turned on, The indicator light of the preset key lights up even when the preset key is pressed, and the equalization characteristics are applied depending on the contents of the corresponding preset memory and operation starts, making operation extremely easy and making it easier to use with high-end equipment. It can fully enhance the mood.

Furthermore, in the above embodiment, the microcomputer 20
The ROM 22 or a separate ROM is provided, standard preset data is stored in it, and the control data stored in the preset memory area of the RAM 23 is included in the initialization operation program when the power is turned on. When the data turns out to be meaningless, the above
A program has been added that reads the standard control data stored in the ROM and writes it to the preset memory area of the RAM 23. According to this program, when the user turns on the power switch for the first time after shipping from the factory, The equalization characteristics are always kept in the specified state even when the control data stored in the preset memory area of the RAM 23 is destroyed when the power is turned on due to some reason such as a failure of the backup power supply. It is possible to prevent abnormal audio from being played.

Next, the audio signal input to such a PGEQ is usually supplied from a tape deck of a car stereo, and further from an FM-AM tuner or the like.

Therefore, as an embodiment of the present invention, the display mode of the matrix display 26a of the display section 26 is switched not only to the above-mentioned frequency characteristic display mode and level display mode, but also to a tape deck operation display mode and a tuner operation display mode. You may also do so.

FIG. 6 shows one embodiment of the system, in which 40 is a tape deck, 41 is a tuner, 42 and 43 are analog-to-digital converters (A/D), and the others are the first
This is the same as the embodiment shown in the figure.

Various data representing the operation status or operation status of the tape deck 40, such as data D such as volume (VOL), balance (BAL), sound quality (BASS, TRE), fader (FADER), etc., are left unchanged.
The signal levels L and _RL are each taken in by the I/O 24 of the microcomputer 20 via the A/D 42.

The same goes for the tuner 41, the data T representing the tuning frequency remains unchanged, and the signal level
L _S is respectively taken into the microcomputer 20 via the A/D 43.

FIG. 7 shows an embodiment of the switch section 25 and the display section 26.
In addition to 1, a deck display key 25m and a tuner display key 25n are provided, and on the other hand, on the display section 26,
The matrix display 26 has 8×9 display elements 26
a(1), and further includes indicator lights 26m and 26n for the keys 25m and 25n, and an illumination part for identifying display contents, and this illumination part is an EQ display part 26a(2). , the deck display section 26a(3), and the tuner display section 26a.
(4), and further includes tuner tuning frequency display portions 26a(5) and 26a(6).

Therefore, when the deck display key 25m is pressed now, it is read by the program of the microcomputer 20 and the program for the display section 26 is switched to the deck display, so the indicator light 26m lights up and at the same time the deck display section 26a (3) is illuminated. Note that when neither of the keys 25m and 25n is pressed, the EQ display portion 26a(2) is illuminated.

At this time, as shown in FIG. 8, VOL, BAL,
BASS, TRE, etc. are displayed by the lighting position of the display element 26a(1) in the vertical direction, and at the same time, the levels L and R of the left channel and right channel signals are displayed in the form of a bar graph.

Further, when the tuner display key 25n is pressed, the indicator light 26n lights up and the tuner display portion 26a(4) is illuminated, and furthermore, the tuner display section 26a(4) is illuminated.
As shown in FIG. 9, either one of the tuning frequency display parts 26a(5), 26(6) is illuminated depending on the operating state of the tuning frequency display element 2 in the horizontal direction.
It is displayed by the lighting position of 6a(1), and the level of the received signal is also displayed in the form of a horizontal bar graph.

Furthermore, when f special/level key 25l is pressed,
The EQ display section 26a(2) is illuminated, and at this time
GEQ equalization characteristics and level display are key 2
The operation of switching alternately each time 5l is pressed is the same as in the embodiment shown in FIG.

Therefore, according to this embodiment, in a car stereo equipped with a tuner, etc., all of its operation status and operation status can be known from the display unit 26,
Operation is easy and always accurate.

In the above embodiment, the control data for GEQ is set using the slide encoders 25a to 25.
Although this is done by pressing e, an encoder that is automatically operated by up and down keys may be used instead.

Further, as the matrix display 26a, any one such as a light emitting diode, liquid crystal, or fluorescent display tube may be used, and if necessary, a cathode ray tube or the like may be used.

As explained above, according to the present invention, necessary equalization characteristics can be set with a single touch using control data preset in memory.
Even with PGEQ, when you turn on the power, you can always set the correct equalization characteristics, so you can eliminate the shortcomings of conventional technology, and you can always perform accurate operation, making it a high-class PGEQ that is easy to use. We can provide high-end car stereos with

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the equalizer device according to the present invention, Fig. 2 is a front view showing an example of the operation panel thereof, Fig. 3 is an explanatory diagram showing the frequency characteristic display mode, and Fig. 4 is a level view. FIG. 5 is a block diagram showing an example of the detection section, FIG. 5 is an explanatory diagram showing the level display mode, FIG. 6 is a block diagram showing another embodiment of the present invention, and FIG. 7 is a front view showing an example of the display section. 8 and 9 are explanatory diagrams showing display modes. 1... Graphic equalizer section, 2... Control section, 3... Level detection section.

Claims (1)

[Claims] 1. A signal transmission circuit whose frequency characteristics over almost the entire audio signal frequency band can be controlled by electrical control data, a memory means capable of writing and reading the control data, and generation of the control data and the memory. A graphic equalizer device comprising operation input means for controlling the writing and reading of control data to and from the means and capable of presetting equalization characteristics, comprising control data storage means for saving the contents of the memory means when the power is turned off. , a fixed memory means for holding predetermined standard control data independently of the control data generated from the operation input means, and a control data determination means for examining the control data read from the memory means when the power is turned on. When the power is turned on, the equalization characteristics are preset using the control data stored in the memory means, and when it is determined that there is an abnormality in the control data read out from the memory means, the control data is read out from the fixed memory means. An equalizer device characterized in that it is configured to preset equalization characteristics using standard control data.