JPS5916219B2 - spectrum display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spectrum display device, which is a spectrum display device capable of monitoring in which part of each frequency band an input signal of a channel having a high level among input signals of a plurality of channels has a maximum level. The purpose is to provide a display device.

An embodiment of the spectrum display device according to the present invention will be described below with reference to the drawings.

For example, in an audio stereo tape deck,
A VU meter and a spectrum display panel are installed to display the signal level of the input signal and its frequency distribution at the same time, confirming at what frequency excessiveness is occurring, and reducing the level of the problematic spectrum part. The recording level for each frequency is adjusted correctly to achieve good recording without distortion.

1 and 2 respectively show a block system diagram of an embodiment of the spectrum display device according to the present invention and a schematic front view of a stereo cassette deck incorporating the same.

In FIGS. 1 and 2, the attenuators 3a and 4a are set at the same position, respectively. For example, an input audio signal of the L channel inputted from the input terminal 1 is supplied to the VU meter 2L, and is attenuated by the attenuator 3a to 5 appropriate signal levels, such as center frequencies 4O, 150, 40O, IK, 2.4, 6,
The signal is supplied to narrow band filters 51 to 57 of 13KH2 and a full band filter 58 having a wide band (audio frequency band) including all of these frequency bands. The signal is divided into 007 frequency bands to become a spectrum signal, and becomes a full-band signal including all seven frequency bands.

The spectrum signal and full-band signal divided into each frequency band by the narrow-band filters 51 to 57 and the full-band filter 58 are supplied to a rectifying and smoothing circuit 6 following the filters 51j5 to 57 and 58, respectively, for rectification and smoothing. be done.
The above signal processing is performed on the R channel signal inputted from the input terminal 7 in exactly the same manner.

That is, the signal coming from terminal 7 is sent to VU meter 2R.
At the same time, it is attenuated by the attenuator 4a with the same attenuation amount as the L channel, and is passed through the narrowband filters 81 to 8.
7 to become a spectral signal, which is then passed through an all-band filter 88 to become a full-band signal, which is then rectified and smoothed by a rectifying and smoothing circuit 9, respectively. rectifier smoothing circuit 6,
The L channel and R channel spectral signals and full band signals rectified and smoothed in step 9 are supplied to gate circuits 101 to 108 provided for each frequency band, while the full band signals of each channel are compared. The signal is supplied to the circuit 12 and compared, and a signal (for example, an H level signal) corresponding to the channel with a higher level (for example, the L channel) in the entire band is taken out and sent to the gate circuits 101 to 1.
It is supplied to the control terminal 11 of 08. Here, the gate circuits 101 to 108 are driven low by the H level signal from the comparator circuit 12 among the signals input from the rectifying and smoothing circuits 6 and 9.
The signal transmission path of the channel is opened, while the signal transmission path of the R channel is closed by an L level signal. For this reason, gate circuits 101 to 1
08 opens the signal transmission path of the L channel by the H level signal from the comparator circuit 12, and thereby, only the signal from the rectifying and smoothing circuit 6 passes through the gate circuits 101 to 108 to the multiplexer and the level axis 1 drive circuit ( (hereinafter referred to as a display drive circuit) 13.

The signal supplied to the display drive circuit 13 is sequentially time-divided in series with a number of decoded signals corresponding to the number of each frequency band and all bands from a decoder (not shown), and is taken out as a serial signal. A comparator (not shown) is supplied. Comparators are provided corresponding to the number of levels provided on the level axis of the spectrum display panel 14, and each comparator has one input terminal connected to the power supply voltage +Vcc.
Comparison reference voltages of different magnitudes are applied, each divided by a resistor. The signal supplied to the comparator is compared with each comparison reference voltage, and if the human input voltage is greater than the comparison reference voltage at each comparator, one drive output is taken out from that comparator, and the display panel 1
4 level axis display circuit (not shown). On the other hand, the signal from the decoder is supplied to a frequency axis drive circuit (not shown) of the display panel 14, becomes a drive signal, and is supplied to a frequency axis display circuit (not shown).

The display panel 14 is composed of a spectrum display element 14a and a full-band display element 14b arranged in parallel on the right side of the spectrum display element 14a, and displays signals taken out corresponding to each level from the display drive circuit 13 and a frequency axis drive circuit. Each narrow band frequency of 40
~13KHz and a time-division signal taken out corresponding to all band frequencies, and thereby, the full band display element 14b displays the peak level of the input audio signal, and the spectrum display element 14a displays the frequency. Show distribution. In this case, since the comparator circuit 12 detects the channel with the higher level of the L channel signal and the R channel signal, the spectrum display element 14a detects each of the channels with the higher level (for example, the L channel). The maximum level for each frequency band can be displayed. in this case,
By configuring each display element (not shown) to be lit according to the output signal of the comparator circuit 12, it is possible to easily determine in which channel of the L channel and the R channel the maximum level is occurring. obtain. Furthermore, if the full-band display element 14b is used as a heater level meter, the peak level just before reaching an overload level (for example, +5 dB) can be monitored, and by using it together with the VU meters 2L and 2R, the recording level can be adjusted correctly. .

At this time, it has the same center frequency as this device,
By using a level-controllable graphical equalizer in conjunction with the system, you can accurately monitor on the spectrum display that a state that is about to reach the above-mentioned overload occurs in a certain frequency range, and use the graphical equalizer to adjust the level of the problematic frequency range. It is effective to lower the input signal to a normal level and extract the output signal from this graphic equalizer.

In addition, as shown in FIG. 1, the display panel 14 has a spectrum display element 14a and a full-band display element 14b arranged side by side adjacently, and the level display scales of the display elements 14a and 14b are aligned. Because of this structure, the relative relationship between the overall band level and the spectral level distribution can be easily displayed using only a pattern of high and low levels, making it easy to visually check.

Furthermore, if fluorescent display tubes are used for the display elements 14a and 14b,
It has good responsiveness to input signals, does not cause instruction errors such as instruction delays, and can accurately display levels. Also, when displaying the spectrum levels of two stereo channels, rather than displaying the spectrum of the input signals of the two channels on two display panels separately, it is better to display the spectrum level of the channel with the higher level on one display. Displaying on a board is easier to monitor and can be constructed at a lower cost. On the other hand, a channel that is particularly desired to be monitored may be selected from among the L channel and the R channel, and the frequency distribution of the input signal of that channel may be investigated.

For example, when examining the R channel signal, the attenuator 3a is moved, for example, downward in FIG. 2, and set to the maximum attenuation position. As a result, the L channel input signal coming from the input terminal 1 is greatly attenuated compared to the R channel input signal coming from the input terminal 7, and the comparison circuit 12
The output becomes an L level signal corresponding to the R channel and opens the R channel signal transmission path of the gate circuits 101 to 108, and the display panel 14 displays the vector and full band of the R channel signal. When examining the L channel signal, the attenuator 4a is set to the maximum attenuation position, contrary to the above case. In addition, the attenuators 3a, 4
Switches a are linked to switches 3b and 4b connected between the AC power source and the fluorescent display tube of the display panel 14, respectively, and correspond to each attenuator when the attenuator is moved to the maximum attenuation position. The switch is configured such that the switch is activated. Therefore, by displacing the attenuators 3a and 4a to the maximum attenuation position, AC power is no longer supplied to the fluorescent display tube of the display panel 14, and the display panel 14
can be turned off, saving power. This is used when rewinding the tape, fast forwarding, or other times when no display is required. Further, in FIG. 2, numeral 15 is a polyurethane for adjusting the recording level of the deck, which attenuates and increases the input signals of the L channel and R channel by the same amount of attenuation. Note that in the above embodiments, it is not necessary to provide a VU meter.

Further, the number of spectra and the number of levels to be displayed are not limited to those in the above embodiments, and can be freely set by appropriately selecting the number of filters, the number of output signals of the decoder, and the like.

Furthermore, although it would be most convenient to simultaneously display both the full band display and the spectral display as in the above embodiment, it is also possible to provide only the spectral display element without providing the full band display element.

As described above, the spectrum display device according to the present invention includes a plurality of frequency band dividing means that divides an input signal of one channel into different frequency bands, and divides input signals of a plurality of channels into the same frequency band. , the level of the input signal is compared in all bands, and the signal from the frequency band dividing means of the channel with a large level is displayed for each frequency band on one spectrum display panel. Features include the ability to display human input signals of large channels with compared levels in each frequency band, accurately monitor the recording level of each frequency, and perform good multi-channel recording without distortion. have

[Brief explanation of drawings]

1 and 2 are respectively a plotter system diagram of an embodiment of the spectrum display device according to the present invention and a schematic front view of a stereo cassette deck incorporating the plotter system. 1, 7... Input terminal, 3a, 4a...
Attenuator, 51-57, 81-87... band filter, 58, 88... full band filter,
6, 9... Rectifier smoothing circuit, 101-108...
...Gate circuit, 12...Comparison circuit, 13
...Display drive circuit, 14...Display panel,
14a...spectrum display element, 14b...
...Full band display element.

Claims (1)

[Claims] 1. A plurality of frequency band dividing means for dividing the input signal of one channel into different frequency bands and dividing the input signals of the plurality of channels into the same frequency band; 1. A spectrum display comprising: means for comparing the levels in all bands including the frequency bands and displaying the signals from the plurality of frequency band dividing means of the channels having high levels for each frequency band on one spectrum display panel. Device.