JPS5853866B2 - spectrum display device - Google Patents

Description

[Detailed Description of the Invention] The invention relates to a spectrum display device, which allows a real time display, a bold display, and a maximum value display to be selectively displayed on one display panel by a simple switch operation. The purpose is to provide a display device.

For example, when recording with a tape recorder, etc., before recording, the spectrum display device displays the signal level of the input signal (full band display) and at the same time displays the frequency distribution of the input signal (spectrum display). The method is to confirm whether a problem is occurring and to lower the level of the problematic spectrum portion to a normal level.

Conventional spectrum display devices simply display the spectrum of the input signal (real-time display) and stop and display the spectrum level by operating a switch (hold display), and display the spectrum of the input signal at the maximum level. This method has drawbacks such as the inability to display, especially the tendency of the frequency characteristics of the input signal.

In addition, in order to shift the input signal using, for example, a 100-bit shift register, hold it digitally, and supply it to the display drive circuit to display the level, the number of display levels and the number of bits of the shift register are determined. Therefore, in order to increase the number of display levels and monitor level fluctuations in detail, it is necessary to increase the number of bits of the shift register, which has disadvantages such as not being able to be constructed at low cost. was there.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of a spectrum display device according to the present invention.

In the figure, Swl is a real time display switch, and diode D
It is connected to the control terminal 11 of the first switch circuit 20 through the diode D2, and to each control terminal 12 of the rectifying and smoothing circuit 4 through the diode D2.
A voltage +Vcc is applied to the switch circuit 2 and the rectifying and smoothing circuit 4.

sw2 is a hold display switch, which is interlocked with switch 8M, and when closed, releases the closed state of switch 5VJ1.

S'w3 is a maximum value display switch, which is connected to the first switch circuit 2 via a diode D3, and when closed, applies voltage +Vcc to the first switch circuit 2, and connects the rectifier and smoothing circuit 40 control terminal 12 to ground. Potential.

Here, in the figure, when the spectrum of the input audio signal from the input terminal 1 is to be displayed (real-time display), the switch SW1 is closed.

As a result, the switch circuit 2 is closed, and an H level voltage is applied to the control terminal 12 of the rectifying and smoothing circuit 40.

The human-powered audio signal input from the input terminal 1 is transmitted through the switch circuit 2 to the center frequencies f1 to f as shown in FIG.
The signal is supplied to a filter circuit 3 consisting of filters 3, to 3n having n frequency characteristics a1 to an, and is divided into n frequency bands whose spectra are displayed on a display panel 8, which will be described later.

The signal divided into each frequency band by the filter circuit 3 is
The signals are supplied to the rectifying and smoothing devices 4, .about.4n of the rectifying and smoothing circuit 4, which follow the filters 3, .about.3n, respectively, and are rectified and smoothed.

The rectifying and smoothing devices 4, to 4n, as shown in FIG. It is configured.

In this case, since an H level signal is applied to the control terminal 12 of the second switch circuit 150 by closing the switch SQ, the switch circuit 15 is in an on state between its input line 16 and output line 17. As a result, the signal input from the input terminal 14 of each of the rectifying and smoothing devices 4 and 4n charges and discharges the capacitor C with the rise time and fall time determined by the resistors R1 and R2 and the capacitor C, and also charges and discharges the capacitor C through the diode D4. The signal is rectified and supplied to the multiplexer 5.

The signal supplied to the multiplexer 5 is the fourth signal from the decoder 10, an n-ary decoded signal d1 as shown at ~Dn.
~dn, are sequentially time-divided in series, taken out as n serial signals, and sent via the buffer circuit 6 to the level axis (Y
shaft) is supplied to the drive circuit 7.

The level axis drive circuit 7 has a number of comparators (not shown) corresponding to the number of levels provided on the level axis of the display panel 80, and each comparator has a power supply voltage connected to its respective negative input terminal. Comparison reference voltages of different magnitudes divided by resistors are applied.

The n series signals supplied to the level axis drive circuit 7 are supplied to comparators and compared with respective comparison reference voltages, and if the input voltage is higher than the comparison reference voltage in each comparator, the drive output is selected from the comparator. and is supplied to a level axis display circuit (not shown) of the display panel 8.

On the other hand, n-ary decoded signals d1 to ci from the decoder 10
n is supplied to the frequency axis (X-axis) drive circuit 9 to become a drive signal, and is supplied to the display panel 80 frequency axis display circuit (not shown).

The display panel 8 is supplied with signals extracted corresponding to each level from the level axis drive circuit 7 and time-division signals extracted corresponding to each frequency band from the frequency axis drive circuit 9. , the frequency distribution of the input audio signal is displayed on the spectrum display element 8a.

Now, in this state (real time display state), the hold display switch SW2 is closed.

As a result, the real time display switch SVg is opened, and the first switch circuit 20 control terminal 11 and the rectifier smoothing circuit 40 are opened.
An L level voltage is applied to the control terminal 12, the first switch circuit 2 is opened, and the connection between the input line 16 and the output line 17 of the second switch circuit 15 of the rectifier and smoothing circuit 4 is opened, and the input terminal The input signal from 1 is not supplied to the filter circuit 3, and on the other hand, charging and discharging of the capacitor C is stopped and the terminal of the capacitor C is held at the voltage at that time.

This hold voltage is supplied to the display panel 8 via the multiplexer 5, buffer circuit 6, and level drive circuit 7, as in the above case.

As a result, the display element 8a of the display panel 8 displays the distribution state of the spectral level at that point in time in a blinking light band for a certain period of time, and the supervisor can easily read the frequency distribution state of the human-powered audio signal.

At this time, since the switch circuit 2 is open, the spectral distribution of the input signal when the switch 5Vv2 is closed can be displayed while being stopped for the period when the switch Sw2 is closed.

Note that since the second switch circuit 15 is formed of a C-MO8 integrated circuit, it is possible to integrate a plurality of circuits on one chip, and the insulation when the input line 16 and the output line 17 are opened is Since the resistance is extremely high, the capacitor C
can reliably prevent charge discharge.

If holding for a sufficiently long time is required, use a diode D4 that is small enough to cause a negligible reverse current, and use a diode D4 that is so small that the reverse current can be ignored. It is sufficient to use an analog switch of a C-MO8 integrated circuit, and further to use an operational amplifier with a high input impedance as the buffer circuit 6.

Next, in the above real time display state, the maximum value display switch group V,
When the switch Sw1 is closed, the real time display switch Sw1 is opened.
An H level voltage is directly applied to the control terminal 11 of the first switch circuit 20, and an L level voltage is applied to the control terminal 12 of the rectifying and smoothing circuit 40.

As a result, the first switch circuit 2 is kept closed, the second switch circuit 15 of the rectifier smoothing circuit 4 is opened, and the output voltage of the rectifier smoothing circuit 4 is held as in the case of the hold display above. .

In this case, since the first switch circuit 2 is closed,
The signal coming from the input terminal 1 is passed through the resistance R of the rectifying and smoothing circuit 4.
1 and a diode D, and are sequentially supplied to a capacitor C.

As a result, the terminals of the capacitor C are held at successively higher voltages, and the maximum level of each frequency band of the input audio signal is stopped and displayed on the display panel BFc.

At this time, the spectrum level is displayed at its maximum value, so when a record is played, it is easy to read the excess or deficiency of high and low frequencies, which is convenient for monitoring the frequency characteristics of the record. .

In this way, according to the device of the present invention, real time display, hold display, and maximum value display can be selectively obtained on one display board 9 by a simple switch operation, and the spectrum during recording and playback can be displayed selectively. Effective for level monitoring and sound field characteristics monitoring.

In addition, since three types of display can be performed only by switching the first switch circuit and the second switch circuit 15, the circuit can be made compact, and since the second switch circuit 15 and the analog switch circuits 51 to 5nKCMO8 integrated circuits are used, From this point of view as well, the circuit can be made compact, and since one capacitor C in the rectifying and smoothing circuit 4 has both smoothing and holding functions, the circuit can be made compact from this point as well.

In addition, a full band filter including all the frequency characteristics a1 to an of the filter shown in FIG. 2 is used, and the filter 31 is mounted on the display panel 8.
It is also possible to display the spectrum level based on ~3n and also display the full band level based on the full band filter.

In addition, when used in conjunction with a graphic equalizer that has the same center frequencies f1 to fn as this device and is level controllable, it is possible to accurately monitor on the spectrum display whether a state that is about to reach overload is occurring in a certain frequency range. It would be convenient to lower the level of the problematic frequency portion using a graphic equalizer, bring the input signal to a normal level, and then extract the output signal from the graphic equalizer.

In addition, since the rectifying and smoothing circuit 4 is configured to sample and hold the signal from the filter circuit 3 as an analog quantity, it is different from the conventional device that shifts the signal using a shift register, holds it digitally, and displays the level. Even when the number of display levels is increased, there is no need to increase the number of circuits.

Further, the display method of the display panel 8 may be a light band display or a light spot display. For example, a light band display is displayed during real time display,
It may be configured to switch to display a light spot during hold display.

Furthermore, the first switch circuit 2 may be configured to open/close between the input of the filter circuit 30 and the ground.

Further, the switches SW1 to Sw3 are not limited to the configuration shown in FIG. 1, but may be of any configuration as long as they have the same function as the above operation.

Moreover, the analog switch circuits 51 to 5 of the multiplexer 5
If it is not possible to maintain a sufficiently high input impedance when N is off, connect a high input impedance buffer circuit to the output side of the rectifier and smoother 4□~4n, and send the output signal from this buffer circuit to each analog switch circuit 5~4n. 5n.

As described above, the spectrum display device according to the present invention includes a frequency band dividing means that divides an input signal into a plurality of frequency bands and outputs the divided filter circuits, and a frequency band dividing means and an input terminal. is provided between the frequency band dividing means and the input terminal when opened to supply the input signal to the frequency band dividing means, and disconnects the frequency band dividing means and the input terminal when opened. A first switch circuit configured to prevent the input signal from being supplied to the frequency band dividing means, a rectifier, a capacitor, and a second switch circuit connected to both ends of the capacitor via a discharge resistor, respectively. rectifying and smoothing means comprising a plurality of rectifying and smoothing devices that respectively rectify and smoothing output signals from the plurality of filter circuits; and outputs from the plurality of rectifying and smoothing devices each having a plurality of frequency bands corresponding to the frequency band dividing means. The display panel includes at least a display panel that displays signal levels in spectra, and a display mode changeover switch that selectively opens and closes the first and second switch circuits, respectively, and displays the display mode changeover switch in real time. By switching to the mode, the first switch is closed and the second switch circuit is closed, and the charging and discharging time constants of the time constant circuits of the capacitors and discharging resistors in the respective rectifying smoothers close the first switch and close the second switch circuit. A spectrum distribution is displayed in real time on the display panel with predetermined rise and fall times, and by switching the display mode changeover switch to the maximum value display mode, the first switch is closed and the second The switch circuit is opened, and the charges in the capacitors in the respective rectifiers and smoothers are not discharged from the second switch circuit, so that the display panel shows a high level value for each frequency band in the spectrum. is displayed, and further, by switching the display mode selector switch to the hold display mode, the first switch is opened and the second switch circuit is also opened, so that the supply of the input signal is cut off and the respective input signals are Since the charge in the capacitor in the rectifier and smoother is not discharged from the second switch circuit, the level value for each frequency band is displayed as a spectrum on the display panel at the time when the display mode selector switch is switched to the hold display mode. With a simple switch operation, you can selectively display the input signal's real-time display, hold display, and maximum value on a single display panel, allowing you to monitor the spectral level during recording and playback. It is convenient for monitoring the characteristics of the sound field, and in particular, the spectrum can be displayed at the maximum level, so when playing a record, it is easy to read the excess or deficiency of high and low frequencies, and the frequency of the record can be easily read. It is convenient for monitoring characteristics, and since the three display modes described above can be obtained by simply switching the first and second switch circuits, the circuit can be made compact.
Furthermore, since the hold means is configured to be supplied with the band-divided signal as an analog quantity and hold it, it is compared to conventional devices that shift the signal using a shift register, hold it digitally, and display the level. Even if the number of display levels is increased by increasing the number of display levels, there is no need to increase the number of circuits, and it has the advantage that it can be constructed easily and inexpensively.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the spectrum display device according to the present invention, Fig. 2 is a frequency characteristic diagram of the filter circuit of the device shown in Fig. 1, and Fig. 3 is a rectification diagram of the device shown in Fig. 1. Specific circuit diagram of smoothing circuit and multiplexer, Figure 4D
1 to Dn are output signal waveform diagrams of the decoder of the device shown in FIG.
Switch circuit, 3...Filter circuit, 4...
... Rectification and smoothing circuit, 5 ... Multiplexer,
7... Level axis drive circuit, 8... Display panel, 8a... Display element, 9... Frequency axis drive circuit, 10...・Decoder, 15...
...Second switch circuit, R1, R2...Resistance,
Dl D4...Diode, C...Capacitor, S'w1~SW,...Display mode changeover switch.

Claims (1)

[Claims] 1. Frequency band dividing means configured by a plurality of filter circuits, which divides an input signal into a plurality of frequency bands and outputs the resultant signals, and a frequency band dividing means provided between the frequency band dividing means and the input terminal when the frequency band dividing means is closed. and the input terminal to supply the input signal to the frequency band dividing means,
a first switch circuit that disconnects the frequency band dividing means and the input terminal when closed to prevent the input signal from being supplied to the frequency band dividing means; a rectifier, a capacitor, and a discharge across the capacitor; rectifying and smoothing means each having a second switch circuit connected via a resistor and rectifying and smoothing the output signals from the plurality of filter circuits, respectively; a display panel having a plurality of corresponding frequency bands and displaying spectra of the levels of output signals from the plurality of rectifiers and smoothers, and the first and second switch circuits are selectively combined to open and close, respectively. and a display mode changeover switch, and by switching the display mode changeover switch to the real-time display mode, the first switch is closed and the second switch circuit is closed, and the respective rectification and smoothing circuits are closed. The rise time and fall time determined by the charging and discharging time constant of the time constant circuit formed by the capacitor and discharge resistor in the device are displayed in real time as a spectrum distribution on the display panel, and the display mode changeover switch is set to maximum value display mode. By switching, the first switch is closed and the second switch circuit is opened, so that the charge stored in the capacitor in each of the rectifiers and smoothers is not discharged from the second switch circuit, thereby causing the display to occur. A high level value is displayed as a spectrum for each frequency band on the panel, and furthermore, by switching the display mode selector switch to the hold display mode, the first switch is opened and the second switch circuit is opened. is also opened, the supply of the input signal is cut off, and the charges in the capacitors in the respective rectifiers and smoothers are not discharged from the second switch circuit, so that the display mode changeover switch is set to the display mode on the display panel. 1. A spectrum display device that continues to display a spectrum of level values for each frequency band at the time of switching.