JPH0321060Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a graphic equalizer suitable for in-vehicle audio equipment such as car stereos.

[Background of the invention and problems]

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 acoustic characteristics in cars and adjust frequency characteristics through programs. 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 frequency 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.
By installing GEQ in a car stereo, the above requirements can be met.

By the way, this GEQ has a large number of variable resistors or switches for frequency characteristic adjustment corresponding to each of the channels mentioned above, so operating them requires considerable skill and is still quite troublesome. This is a rather cumbersome operation.

Therefore, not only does it put a considerable psychological burden on the user to repeatedly operate the GEQ when changing programs, but it also puts a heavy burden on the user, especially when used as an in-vehicle device such as a car stereo. There was a risk that it would become extremely undesirable from a safety standpoint.

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. For example, the so-called presettable GEQ that made it possible to
It has been proposed as No. 118276 etc.

According to this presettable GEQ (hereinafter referred to as PGEQ), it can be installed in a car stereo, etc., and can be easily and safely operated to always provide the necessary equalization characteristics accurately. It can fully demonstrate its functions as an audio device, and is fully capable of achieving high performance and high-end equipment such as car stereos.

Therefore, a method was devised in which a ROM (read-only memory) was installed in the PGEQ, and control data that provided standard equalization characteristics was set at the manufacturing stage of car stereos and other products.

However, as is well known, the sound reproduction characteristics of audio equipment such as car stereos are highly dependent on the acoustic characteristics of the space itself, such as the interior of a car, where the audio is to be reproduced from the equipment. They vary greatly depending on the type of car and how it is used.

Therefore, with the method described above in which predetermined equalization characteristics are given at the time of manufacturing using ROM etc., the predetermined sound reproduction characteristics will not be the same when actually used in the cabin of a car as a car stereo etc. The drawback was that only different characteristics could be obtained.

Therefore, in order to eliminate this drawback, a method was devised in which the user can write control data for an arbitrary equalization characteristic into a memory separate from the ROM of the PGEQ as described above.

However, even in such PGEQ,
Presetting control data requires a large number of man-hours, is troublesome, and is inconvenient.

This is because the PGEQ display panel can display the equalization characteristics (hereinafter referred to as EQ display) and the output level of the audio signal GEQ (hereinafter referred to as level display). Conventionally, a switch or the like is provided to switch between EQ display and level display. For example, when audio, music, etc. is being played and the PGEQ display panel is displaying the level, When the user wants to write new equalization characteristics, first use the switch to change the display panel to EQ display, then press the up/down keys or preset memory to obtain the desired equalization characteristics. It was necessary to write the desired equalization characteristics into the memory by operating a key or the like, and then to switch again to display the level using the switch.

However, when using a GEQ, the display panel often displays the level of the audio signal, and the EQ display is generally shown on the display panel only when changing the equalization characteristics.

However, when adjusting the frequency characteristics of an equalizer device, which is frequently used due to differences in the frequency characteristics of the music being listened to, it is necessary to first operate the display switching key and switch the display to the frequency characteristics display. It is very troublesome to make adjustments above. Furthermore, when a large number of different types of keys are arranged on the operation surface, it is very troublesome to have to search for the display switching key each time.

[Purpose of invention]

In light of the above, an object of the present invention is to improve the operability when adjusting frequency characteristics in an equalizer device that can control frequency characteristics over almost the entire audio signal frequency band.

[Example of idea]

Hereinafter, embodiments of the automatic equalizer device according to the present invention will be described with reference to the drawings.

Figure 1 is a block diagram showing an embodiment of the present invention controlled by a microcomputer.
1 is bridge amplifier, 2 is analog switch, 3
4 is a 4-bit data latch, 5 is a microcomputer, 6 is a keyboard device with a key matrix, 7 is a decoder, 8 is a display device, 9 is a segment driver,
10 is a digit driver, 11 is a bandpass filter, 12 is an analog switch, and 13 is an A/D.
(analog-digital converter), 14 and 15 are mutating circuits, 16 is a pink noise generator,
17 is a microphone, 18 is a head amplifier, 19
20 is a line amplifier, 20 is a mixing circuit, and 21 is an auto equalizer latch.

Bridge amplifier 1 has n analog switches 2
is coupled to n simulated inductors 3 through the auxiliary inductors 3, and divides the audio signal frequency band into a number of channels, for example, n types of channels;
The amount of attenuation (or gain) for each channel is controlled according to the switching state of the n analog switches 2, giving an arbitrary frequency characteristic to the audio signal from the input terminal IN and transmitting it to the output terminal OUT. Therefore, by supplying predetermined control data to the analog switch 2, it operates as a GEQ.

Microcontroller 5 is a CPU (central processor).
It consists of a ROM for storing programs, a RAM (random access memory) for storing data, and an I/O (input/output device).
Processing according to a predetermined program is performed in accordance with input data from the keyboard device 6, which is configured with a key matrix and serves as an input operation device, and writes control data input from the keyboard device 6 to, for example, a 4-bit data latch 4. and writing to a predetermined memory area of RAM, and writing control data read from a predetermined memory area of RAM to data latch 4.
Switching control of the analog switch 2 is performed using control data from the analog switch 2. Therefore, by operating the keyboard device 6, it will operate as a PGEQ.

The display device 8 is capable of two-dimensional display, such as a matrix display, and is provided with display data from the microcomputer 5 via the segment driver 9 and digit driver 10, and is provided to the analog switch 2 via the data latch 4. The display corresponds to the control data currently in use, and the frequency characteristics currently given by GEQ are displayed. Therefore, even when preset control data is selected using the keyboard device 6 and an equalization characteristic is given, the equalization characteristic can be directly and accurately grasped visually, and the control can be performed correctly. You will be able to do that.

The n bandpass filters 11 each have a pass characteristic corresponding to n types of GEQ channels, and are sequentially and periodically switched by the analog switch 12 to equalize the audio signal that appears at the output of the bridge amplifier 1. The signals for each channel are sequentially selected and supplied to the A/D 13, which converts them into digital signals and inputs them to the microcomputer 5.

Therefore, the microcomputer 5 detects the signal level of each channel of the output audio signal, and selectively displays it on the display device 8 by inputting it from the keyboard device.
Provided as display data to. As a result, the display device 8 is switched between the above-described frequency characteristic display mode and output signal level display mode by input from the keyboard device 6, and when switched to the output signal level display mode, each channel of the output signal Each level can be displayed simultaneously in a bar graph, allowing you to understand the operating status in real time.

In addition, in the above operating state, data latch 4, segment driver 9, analog switch 1
2 is supplied from the microcomputer 5 via a decoder 7, and at the same time, signals are supplied from the decoder 7 to the keyboard device 6, which controls the lighting of indicator lights indicating the operation status of various keys. etc. are also becoming practiced.

Further, the segment driver 9 is for selecting display elements in the vertical direction of the display device 8, and the digit driver 10 is for selecting display elements in the horizontal direction.

The above describes the normal operation of the PGEQ, and the operation of the automatic equalizer device according to the present invention will be explained below.

The muting circuits 14 and 15 are operated by a signal from an auto equalizer switch (not shown) disposed in the keyboard device 6, and the muting circuits 14 and 15 are not turned on during the above-mentioned normal PGEQ operation. However, when the auto equalizer switch of the keyboard device 6 is turned on and the automatic preset operation mode is selected, the muting circuits 14 and 15 are turned on, the audio signal transmission path is cut off, and at the same time, the pink noise generator 16 is turned on. Driven.

The pink noise generator 16 generates a test signal containing all frequency components at substantially the same level over substantially the entire audio signal frequency band.

The microphone 17 is installed in a car cabin or the like that serves as a listening room where audio equipment such as a car stereo equipped with this PGEQ is installed, and is exposed to the sound field formed by the speakers of the audio equipment to detect audio signals. Let's do it.

Therefore, the keyboard device 6 is now operated,
Assume that a switch to automatic preset operation mode is input.

As a result, the auto-equalizer latch 21 is held, and an auto-equalizer mode command is input to the microcomputer 5 to switch the operating program. First, data is given to the data latch 4, and the muting circuit 14,
15 to cut off audio signals, etc.
Note that when this auto-equalizer mode command is output, the display device 8 is in a level display mode. As a result, the signal from the pink noise generator 16 is supplied from the output terminal OUT via the line amplifier 19 to the power amplifier of audio equipment such as a car stereo, and the pink noise signal drives the speaker, creating a sound field in the listening room. This signal is detected by the microphone 17 and becomes an electrical signal, which is then supplied to the input of the bandpass filter 11 via the head amplifier 18. Then, the pink noise signal is divided into each frequency band by the bandpass filter 11.

At the same time, the microcomputer 5 gives data to the data latch 4 and controls the analog switch 2 so that the characteristics of the bridge amplifier 1 are flat over the entire band, for example, the gain in each channel is zero (or the amount of attenuation is zero). ).

Therefore, the level of each frequency of the signal represented by the output of bridge amplifier 1 at this stage is:
It represents a comprehensive frequency characteristic that includes the acoustic characteristics of a listening room such as an automobile cabin where a sound field is formed by audio equipment such as a car stereo.

Next, the microcomputer 5 provides data to the analog switch 12 via the decoder 7, selects n bandpass filters 11 in sequence, and selects the head amplifier 18.
The signal extracted from the output of the bridge amplifier 1 is taken in via the A/D 13, the level of the signal is detected for each channel, and control data to be given to the analog switch 2 is determined according to the detection result, and the control data is applied to the output of the bridge amplifier 1. To obtain a predetermined frequency characteristic of a signal, for example, a substantially flat characteristic within an audio signal frequency band.

Therefore, the microcomputer 5 supplies data to the analog switch 12, selects the bandpass filter 11 of the reference frequency channel, for example, the 800Hz channel, from among n pieces, and adjusts the level of the signal of this channel by A/ When the level of this signal is taken in through D13 and reaches the 0dB level, in other words, when best tuning has been achieved, the levels of all other frequency bands are read by the microcomputer 5 and used for predetermined calculations. This creates frequency characteristics.

This means that the microcomputer 5 sequentially gives data to the analog switch 12, which becomes the reference channel.
Filters other than the 800Hz bandpass filter 11 are selected one after another, each time the level of the signal input via the A/D 13 is compared with the reference value, and the difference is converted into logarithms for reverse correction (signal higher than the reference value). For channels with a low signal level, give attenuation according to the difference, and for channels with a low signal level, give a gain according to the difference), and send it through data latch 4. and supplies it to analog switch 2. In addition, if necessary
The data may be written to a predetermined memory area of RAM.

After the new frequency characteristic data is created in this way, a signal is sent from the microcomputer 5 to release the auto equalizer latch 21 and the muting circuits 14 and 15 are turned off to restore the audio signal and generate pink noise. A signal is issued to stop the device 16.

Therefore, after this, it will operate as a normal PGEQ, and by operating the up/down switch for each channel provided on the keyboard device 6, it can be used as a normal GEQ, and it can also be stored in memory using the preset keys. It can be used as PGEQ by selectively reading control data.

Next, the operation of PGEQ will be explained using Fig. 2 and Fig. 3. Fig. 2 is a diagram showing the operation panel of PGEQ, 22 is a housing, 23 is an EQ display and a level display. In the display section 2, the display section 2
3 corresponds to the display device 8. 2
4 is a sensor, and the sensor 24 corresponds to the microphone 17. 25 is a plurality of up/down switches for adjusting the level of each frequency in which the audio frequency band is divided into a number of channels; 26 is a switch; the switch 26 has an automatic preset operation as an automatic equalizer; This is for switching to the mode. Reference numeral 27 denotes a memory key. Each memory key 27 stores different predetermined frequency characteristic data, and is used to read each memory. 28 is a memory enable key for writing desired frequency characteristic data. 29 is a preset memory key,
If, for example, the memory key 27a of the memory keys 27 is turned on while the preset memory key 29 is turned on, the memory key 27
The frequency characteristic data stored in a is read out.

The above-mentioned up/down switch 25, switch 26, memory key 27, memory enable key 28, and preset memory key 29 constitute the keyboard device 6.

In addition, in this embodiment, six memory keys 27
can read out two types of memory depending on whether the preset memory key 29 is turned on or off. Therefore, in combination with the preset memory key 29, six memory keys 27 can read out 12 types of memory. It is now possible to read memory.

Next, a procedure for the user to read desired frequency characteristic data will be explained. A flowchart of this procedure is shown in FIG. 3A.
If music is currently being played, the display section 23
is a level display that shows the level of music playback. In this state, in order to read desired frequency characteristic data, the user first operates the up/down key 25 corresponding to the desired frequency band. When the signal generated by this key operation is input to the microcomputer 5 (see Figure 1), the display section 23 is switched from the level display to the EQ display as a second step, and the frequency characteristic data that had been stored in memory is displayed. Ru. When the display section 23 is switched to the EQ display, the desired up/down keys 25 can be sequentially operated while checking the characteristic data on the display section 23 as the next third step. As a fourth step, while the up/down key 25 is being operated, the timer inside the microcomputer 5 is reset each time, for example, at an interval of 0.5 seconds.

After the operation of the up/down keys 25 is completed and the desired frequency characteristic data is read,
When a predetermined period of time, for example 3 seconds, has elapsed in the next step,
As the next step, the display section 23 is switched from EQ display to level display to display the level of the music being played. This allows the user to set desired frequency characteristic data.

The flowchart in FIG. 3B is a flowchart when the preset memory key 29 is operated.The difference from the flowchart in FIG. 3B is that the up/down key 25 is operated in the third step in FIG. Instead, in this chart, the memory corresponding to the operated preset memory key 29 is recalled. The other steps are the same as the chart in FIG. 3A, and even during this operation, when the preset memory key 29 is operated, the display section 23
Once switched to the EQ display, this time is held for a set predetermined time, and then the display returns to the level display.

As described above, in the automatic equalizer device of the present invention, when newly setting frequency characteristic data while the display section is displaying the level,
When the up/down key 25 is operated to set frequency characteristic data, the display automatically switches from the level display to the EQ display.Similarly, the automatic equalizer switch 26 and preset memory key 29 are operated. When operated, the display section 23 interrupts level display and switches to EQ display, and automatically returns to level display after a predetermined time.

[Effect of idea]

As described above, according to the present invention, there is provided a signal transmission circuit whose frequency characteristics over almost the entire audio signal frequency band can be controlled by electrical control data, and a memory capable of storing control data controlling the signal transmission circuit. , an input operation section equipped with a frequency characteristic control key for selecting a desired frequency band for gain adjustment, and a display for selectively displaying the output level of the audio signal and the frequency characteristic set for the signal transmission circuit. control for displaying the frequency characteristic stored in the memory on the display section for a predetermined period of time when the frequency characteristic control key is operated while the display section is displaying the output level of the audio signal. When adjusting the frequency characteristics, it is no longer necessary to first operate the display switching key to switch the display to the frequency characteristics display and then perform the adjustment operations described above. Displays can be easily switched even when the display is placed on the operation surface. Therefore, the operability of the equalizer device, which is frequently used due to differences in frequency characteristics such as the genre of music listened to, is further improved. Furthermore, since it is possible to omit a dedicated display switching key, it is possible to save space on the operating surface of the device and reduce costs, and an equalizer device that is more suitable for use in a vehicle, in particular, can be obtained.

[Brief explanation of the drawing]

The drawings all relate to embodiments of the present invention and are
The figure is a block diagram of the automatic equalizer device, and FIG. 2 is a diagram showing the operation panel of the automatic equalizer device.
Figures 3A and 3B are flowcharts showing the operating procedure. 1... Bridge amplifier, 2... Analog switch, 3... Simulated inductor, 4...
Data latch, 5...Microcomputer, 6...Keyboard device, 8...Display device, 11...Band pass filter, 12...Analog switch, 13...A/D (analog-digital converter), 14, 15... Muting circuit, 16... Pink noise generator, 17... Microphone, 19... Line amplifier, 21... Auto equalizer latch, 23... Display section.

Claims (1)

[Claims for Utility Model Registration] A signal transmission circuit whose frequency characteristics over almost the entire audio signal frequency band can be controlled by electrical control data, and a memory capable of storing control data controlling the signal transmission circuit. an input operation section having a frequency characteristic control key for selecting a desired frequency band for gain adjustment, and selectively displaying the output level of the audio signal and the frequency characteristic set in the signal transmission circuit. an equalizer device having a display section, wherein when the frequency characteristic control key is operated while the display section is displaying the output level of the audio signal, the frequency characteristic stored in the memory is displayed on the display section for a predetermined period of time; An equalizer device comprising a control section.