JP4051853B2 - Display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device that analyzes and displays a distribution of frequency components of an acoustic signal.
[0002]
[Prior art]
Conventionally, a reproduction apparatus capable of reproducing a plurality of recording media such as an MD (Mini Disc), a CD (Compact Disc), and a cassette tape has been provided with a display device that analyzes and displays a distribution of frequency components of an acoustic signal. is doing. This display device divides an acoustic signal reproduced by a reproduction device into predetermined bands, analyzes the distribution of each frequency component, and displays the magnitude of the signal level of each band. For example, in the case of a 7-band display device, frequency components indicating levels for each band of 100 Hz, 220 Hz, 470 Hz, 1 kHz, 2.2 kHz, 4.7 kHz, and 10 kHz are displayed on the display unit. The frequency of each band is not limited to this example, but the frequency of the highest band is generally set to 10 kHz to 16 kHz. This is because the reproduction frequency range of recording media such as MD, CD, and cassette tape is 20 kHz or less, and it is not necessary to display the level of a band exceeding the audible frequency.
[0003]
However, due to technological progress in the structure and recording system of recording media in recent years, for example, the reproducible frequency range of DVD-audio has reached 96 kHz, and a level display of a band exceeding the audible frequency is required.
[0004]
[Problems to be solved by the invention]
Natural sound tends to decrease in level as frequency increases. For this reason, in order to display a band exceeding the audible frequency on the same scale as the audible frequency band, it is necessary to display a level with higher sensitivity. However, MD, CD, and FM broadcast playback signals include aliasing noise and pilot signal noise in a frequency band that exceeds the audible frequency. When a reproduced signal containing these noises is displayed on a display device equipped with a level display in a band exceeding the audible frequency, the sound signal is not included in the band exceeding the audible frequency due to the noise described above. There is a problem that the level of the band is displayed incorrectly.
[0005]
In addition, when performing high-sensitivity level display, if the Q value of the band division filter is not increased, the band division filter that extracts the band exceeding the audible frequency also extracts the frequency component of the audible frequency, and the band exceeds the audible frequency. Has a problem that it is erroneously displayed as a level of a band exceeding the audible frequency even though it does not contain an acoustic signal.
[0006]
The present invention is a display device that extracts each frequency component for each predetermined band and displays the magnitude of the signal level, and can detect and display the signal level of the frequency component exceeding the audible frequency while being audible by the noise component. The object of the present invention is to provide a display device that prevents erroneous display of signal levels of frequency components exceeding the frequency.
[0007]
[Means for Solving the Problems]
In order to solve this problem, the display device of the present invention includes an input selection unit that selects a desired input signal from a plurality of input signals, and each frequency component for each predetermined band from the input signal selected by the input selection unit. A band-pass filter that extracts the signal level, a level detection unit that detects the signal level of each band extracted by the band-pass filter, and a display unit that can display the magnitude of the signal level of each band detected by the level detection unit A band selection unit that selects whether the signal level is displayed or not on the display unit for each band, a control unit that controls the input selection unit and the band selection unit, and operates the control unit Operating means, and the control means switches the selection of the input selection means by operating the operating means, The band selection means in response to the selection of the input selection means in which is configured to switch the display or non-display selection of each band.
[0008]
As a result, in a display device that extracts each frequency component for each predetermined band and displays the magnitude of the signal level, the acoustic signal can detect and display the signal level of the frequency component that exceeds the audible frequency, but the audible frequency due to the noise component. It is possible to prevent erroneous display of signal levels of frequency components exceeding.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, an input selection unit that selects a desired input signal from a plurality of input signals, and each frequency component is extracted for each predetermined band from the input signal selected by the input selection unit. A band pass filter, a level detection means for detecting the signal level of each band extracted by the band pass filter, a display means capable of displaying the magnitude of the signal level of each band detected by the level detection means, Band selection means for selecting display or non-display of the signal level in the display means for each band, control means for controlling the input selection means and the band selection means, and operation means for operating the control means The control means switches the selection of the input selection means by the operation of the operation means, and the input selection means In accordance with the selection, the band selection means switches the display or non-display selection of each band, and extracts each frequency component from the acoustic signal for each predetermined band. In a display device that displays the signal level, it is possible to detect and display the signal level of the frequency component exceeding the audible frequency, but to prevent the signal level of the frequency component exceeding the audible frequency from being erroneously displayed due to the noise component. Can do.
[0010]
According to a second aspect of the present invention, the display device according to the first aspect is provided in a reproducing apparatus capable of reproducing a plurality of types of recording media having different structures, and the reproducing apparatus reproduces the recording medium according to the structure of the recording medium reproduced by the reproducing apparatus. The input selection means selects an input signal and the band selection means switches between selection of display and non-display of each band, and noise is generated in a band exceeding the audible frequency during reproduction from the structure of the recording medium to be reproduced. If the signal level of the band exceeds the audible frequency due to the noise component, the signal level of the frequency component exceeding the audible frequency can be detected and displayed by hiding the signal level of the band. It is possible to prevent the signal level from being erroneously displayed.
[0011]
According to a third aspect of the present invention, there is provided the display device according to the first or second aspect, wherein the display device is provided in a reproduction device capable of reproducing a plurality of types of recording media having different acoustic information recording formats, and the reproduction device reproduces the recording medium. According to an acoustic information recording format, the input selection means selects an input signal and the band selection means switches between selection of display or non-display of each band, and recording of acoustic information of a recording medium to be reproduced If it is determined from the format that noise occurs in the band exceeding the audible frequency during playback, the signal level of the frequency component exceeding the audible frequency can be detected and displayed by hiding the signal level of the band. However, it is possible to prevent the signal level of the frequency component exceeding the audible frequency from being erroneously displayed due to the noise component.
[0012]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
[0013]
(Embodiment 1)
FIG. 1 is a block diagram of a playback device including a display device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an MD playback unit, which includes a mechanism and mechanism control necessary for MD (Mini Disc) playback, a decoder and a converter for decoding a playback signal, and outputs an audio signal played back from the MD. . Reference numeral 2 denotes a CD / DVD playback unit, which can play back either a DVD (Digital Versatile Disc) or a CD (Compact Disc). It includes a playback mechanism and mechanism control for both DVD and CD, which are recording media having different structures, and a decoder and converter capable of playing back multiple types of audio information recording formats. In addition to outputting an audio signal reproduced from a DVD or CD, discriminating information about the structure of the recording medium and the type of acoustic information recording format is output. A tape reproducing unit 3 includes a mechanism and mechanism control necessary for reproducing the cassette tape, and an equalizer amplifier for amplifying the reproduced signal, and outputs an audio signal reproduced from the cassette tape.
A tuner 4 receives a desired broadcast program and outputs an audio signal.
[0014]
Reference numeral 5 denotes a display device, which includes an input selection unit 51, a bandpass filter 52, a level detection unit 53, a display unit 54, a band selection unit 55, a control unit 56, and an operation unit 57. The input selection unit 51 selects a desired audio signal from a plurality of input audio signals. The bandpass filter 52 includes 15 bandpass filters 521 to 5215, and extracts each frequency component for each predetermined band from the input signal selected by the input selection unit 51. The frequency components extracted by each bandpass filter are detected by the 15 level detection units 531 to 5315 of the level detection unit 53. The magnitude of the signal level detected by each level detection unit is displayed on the display unit 54, but a band selection unit 55 is provided between the display unit 54 and the level detection unit 53. Whether the level is large or small can be selected for each band. Reference numeral 56 denotes a control unit, and 57 denotes an operation unit. By operating the operation unit 57, any desired input is selected from the MD reproduction unit 1, CD / DVD reproduction unit 2, tape reproduction unit 3, and tuner 4. It is possible to play a recording medium or receive a broadcast program. By this input selection operation, the input selection unit 51 is switched to a desired input, and the recording medium output by the CD / DVD reproduction unit 2 when which input is selected and when the CD / DVD reproduction unit 2 is selected. In accordance with the discriminating information about the structure and the type of the audio information recording format, the band selector 55 is switched to select whether the signal level on the display unit 54 is large or small for each band.
[0015]
Reference numeral 6 denotes an amplifying unit, and 7 denotes a speaker. The audio signal selected by the input selecting unit 51 is amplified by the amplifying unit 6 and acoustically converted by the speaker 7.
[0016]
2 is an explanatory diagram of the operation unit 57 and the display unit 54 of FIG. 1, and FIG. 2A is an explanatory diagram of the operation unit 57 of FIG. Reference numerals 571 to 574 are input selection keys. Reference numeral 571 denotes an MD selection key that selects a reproduction operation of the MD reproduction unit 1 when pressed. Reference numeral 572 denotes a CD / DVD selection key that selects a playback operation of the CD / DVD playback unit 2 when pressed. Reference numeral 573 denotes a tape selection key that selects a reproduction operation of the tape reproducing unit 3 when pressed. Reference numeral 574 denotes a tuner selection key that selects a receiving operation of the tuner 4 when pressed. 575 to 578 are reproduction / reception operation keys, 575 is a minus music selection / channel selection key, 576 is a stop key, 576 is a reproduction key, and 578 is a plus music selection / channel selection key.
[0017]
FIG. 2B is an explanatory diagram of the display unit 54 in FIG. 1, 30 to 90k indicate intermediate frequencies of the band, and the level of the band is represented by the length of the rectangle above the number. FIG. 2B shows a display example when a reproduction operation of the CD / DVD reproduction unit 2 is selected and a DVD having an Fs (sampling frequency) of 128 kHz is reproduced.
[0018]
The operation of the display device configured as described above will be described below.
[0019]
FIG. 3 is a flowchart of the control unit 56 of FIG. First, the pressing state of the input selection keys 571 to 574 is determined. The input selection keys 571 to 574 hold the selected state when any key is pressed. When the MD selection key 571 is selected, the input selection unit 51 causes the MD playback unit 1 to be selected. Switch to select. Similarly, in the case of the CD / DVD selection key 572, the CD / DVD playback unit 2; in the case of the tape selection key 573, the tape playback unit 3; and when the tuner selection key 574 is selected, the input selection unit 51 outputs to the tuner 4. Switch. (Step 1 to Step 5)
When MD selection key 571, tape selection key 573, and tuner selection key 574 are selected, 22 kHz to 90 kHz of band selection unit 55 is turned off and the output of the band is not displayed on display unit 54, and the frequency of 31 Hz to 15 kHz is not displayed. Display band output. (Step 6)
When the CD / DVD selection key 572 is selected, the disk information of the disk set in the CD / DVD playback unit 2 is read. If the set disc is not a DVD, 22 kHz to 90 kHz of the band selection unit 55 is turned off, the output of the band is not displayed on the display unit 54, and the output of the band of 31 Hz to 15 kHz is displayed. (Step 8, Step 6)
If it is a DVD, the Fs of the set disc is determined. If Fs is 48 kHz or less, 22 kHz to 90 kHz of the band selecting unit 55 is turned off, the output of the band is not displayed on the display unit 54, and the output of the band of 31 Hz to 15 kHz is displayed. If Fs is 88.2 kHz to 96 kHz, 64 kHz to 90 kHz of the band selecting unit 55 is turned off, the output of the band is not displayed on the display unit 54, and the output of the band of 31 Hz to 44 kHz is displayed. If Fs is 128 kHz or higher, all the band selection sections 55 are turned on and the outputs of all bands are displayed on the display section 54. (Step 8 to Step 11, Step 6)
The reproduction unit or tuner selected by pressing the input selection key 571 to 574 can perform reproduction or reception operation by pressing the reproduction / reception operation keys 575 to 578. This operation is a known technique and will not be described.
[0020]
When the selected reproduction unit or tuner is reproduced or received by operating the reproduction / reception keys 575 to 578, the audio signal is input to the band pass filter via the input selection unit 51. Frequency components are extracted for each band from 31 Hz to 90 kHz by 15 band pass filters 521 to 5215 provided in the band pass filter 52. The signal level of each extracted frequency component is detected by 15 level detectors 531 to 5315. Each detected signal level is selected by the band selection unit 55 as a band to be displayed on the display unit 54 and a band not to be displayed.
[0021]
When playing back a DVD or cassette tape with MD, CD, Fs of 48 kHz or less, or receiving a tuner, 5 bands from 22 kHz to 90 kHz are turned off by the band selection unit 55 and not displayed on the display unit 54 by the above-mentioned control, and 31 Hz. The magnitude of the level of 10 bands up to ˜15 kHz is displayed on the display unit 54. For example, since Fs is 44.1 kHz for a CD, if all 15 bands are displayed on the display unit 54, the level is erroneously displayed in the 44 kHz band due to sampling noise, but 5 bands from 22 kHz to 90 kHz. Is turned off by the band selection section 55, and no erroneous display due to sampling noise occurs on the display section 54.
[0022]
In the case of a DVD whose Fs is 88.2 kHz to 96 kHz, the two bands of 64 kHz and 90 kHz are turned off by the band selection unit 55 and are not displayed on the display unit 54, and the level of the 13 bands from 31 Hz to 44 kHz is displayed on the display unit 54. Is done. When Fs is 128 kHz or higher, all the bands are turned on, and the level of the level of 15 bands from 31 Hz to 90 kHz is displayed on the display unit 54.
[0023]
As described above, according to this embodiment, a playback apparatus capable of playing back a plurality of types of DVDs having different Fs (sampling frequencies) from MD, CD, and cassette tape is provided, and a desired input signal is selected from a plurality of input signals. An input selection unit 51, a bandpass filter 52 that extracts each frequency component from the input signal selected by the input selection unit 51 for each predetermined band, and a signal level of each band extracted by the bandpass filter 52 is detected. Level detector 53, display unit 54 capable of displaying the level of the signal level of each band detected by level detector 53, and display or non-display of the level of the signal level on display unit 54 for each band. A band selection unit 55 to be selected, a control unit 56 for controlling the input selection unit 51 and the band selection unit 55, and a control unit 56 are operated. The control unit 56 switches the selection of the input selection unit 51 in accordance with the type of media to be played by operating the operation unit 57, and the Fs when the media is a DVD, and the input selection unit The display device 5 is characterized in that the band selection unit 55 switches the display or non-display selection of each band according to the selection of 51, and detects the signal level of the 22 kHz to 90 kHz frequency component exceeding the audible frequency. If it is determined that noise occurs in the band exceeding the audible frequency during playback from the type of media to be played back or Fs, the frequency component exceeding the audible frequency or a part of the band is not displayed. By doing so, it is possible to prevent the signal level from being erroneously displayed.
[0024]
【The invention's effect】
As described above, according to the present invention, in a display device that extracts each frequency component for each predetermined band and displays the magnitude of the signal level, the signal level of the frequency component exceeding the audible frequency can be detected and displayed. However, it is possible to prevent the signal level of the frequency component exceeding the audible frequency from being erroneously displayed due to the noise component. The advantageous effect is obtained.
[Brief description of the drawings]
1 is a block diagram of a playback apparatus including a display device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of an operation unit and a display unit in FIG. 1. FIG. 3 is a flowchart of a control unit 56 in FIG. Explanation of]
DESCRIPTION OF SYMBOLS 5 Display apparatus 51 Input selection part 52 Band pass filter 53 Level detection part 54 Display part 55 Band selection part 56 Control part 57 Operation part

Claims (3)

Input selection means for selecting a desired input signal from a plurality of input signals, a bandpass filter for extracting each frequency component for each predetermined band from the input signal selected by the input selection means, and extraction by the bandpass filter Level detecting means for detecting the signal level of each band, display means capable of displaying the magnitude of the signal level of each band detected by the level detecting means, and display or non-display of the magnitude of the signal level in the display means Band selection means for selecting display for each band, control means for controlling the input selection means and the band selection means, and operation means for operating the control means,
The control unit is configured to switch the selection of the input selection unit by operating the operation unit, and the band selection unit switches display or non-display selection of each band according to the selection of the input selection unit. A display device. Provided in a reproducing apparatus capable of reproducing a plurality of types of recording media having different structures, the input selecting means selects an input signal according to the structure of the recording medium reproduced by the reproducing apparatus, and the band selecting means The display device according to claim 1, wherein the display is switched between display and non-display. Provided in a reproducing apparatus capable of reproducing a plurality of types of recording media having different acoustic information recording formats, and the input selection means selects an input signal according to the acoustic information recording format of the recording medium reproduced by the reproducing apparatus, and The display device according to claim 1, wherein the band selection unit is configured to switch between display and non-display selection of each band.

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