JP4273548B2 - Waveform shaping device, display device including the same, and electronic device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waveform shaping device, a display device including the waveform shaping device, and an electronic apparatus. More specifically, the present invention relates to a video signal having a synchronization signal exceeding a black level of a video and an image frame on which the video signal is originally to be displayed. The present invention relates to a waveform shaping device that shapes a synchronization signal so that a portion exceeding the black level of the image of the synchronization signal is not displayed on the display device when displayed on a display device of a different image frame, a display device including the waveform shaping device, and an electronic device .
[0002]
[Prior art]
A case where a conventional HDTV video signal is projected on a multi-scan monitor having a different image frame will be described with reference to FIGS.
FIG. 4 shows an HDTV synchronization signal. As shown in FIG. 4, the HDTV synchronization signal is composed of a ternary level of a positive level C exceeding the black level A of the video, a pedestal level B, and a negative level D. The reason why the ternary level is used in this way is that the synchronization separation performance can be enhanced against noise.
[0003]
Since the HDTV video signal has a horizontal synchronization frequency of 33.75 KHz and a vertical synchronization frequency of 60 Hz, it can be displayed on a display device such as a multi-scan monitor that supports a horizontal synchronization frequency of 30 KHz and a vertical synchronization frequency of 60 Hz. In fact, most display devices for information processing can display HDTV video signals.
[0004]
[Problems to be solved by the invention]
However, since the HDTV video signal is originally configured to be displayed on a display device having an image frame with a horizontal / vertical ratio of 16: 9, this is a multi-scan type with a horizontal / vertical ratio of 4: 3. When displayed on a monitor or the like, the top and bottom of the screen are cut off as shown in FIG. However, this display method is already established as a habit.
[0005]
The problem is that, as shown in FIG. 5B, a portion exceeding the black level of the ternary level synchronization signal of the HDTV video signal is displayed at the bottom of the screen. Since there is only a blanking function corresponding to a 4: 3 screen in a multi-scan type monitor, a waveform shaping device for erasing a portion of the HDTV video signal exceeding the black level of the synchronization signal is provided, or It is necessary to provide a waveform shaping device in the device on the HDTV video signal sending side.
[0006]
The present invention has been made in view of the above points, and has a video signal having a synchronization signal having a portion exceeding the black level of the video, and an image frame different from an image frame in which the video signal is originally displayed. It is an object of the present invention to provide a waveform shaping device, a display device including the waveform shaping device, and an electronic device that can display on a display device and shape the synchronization signal so that the synchronization signal is not displayed on the display device.
[0007]
[Means for Solving the Problems]
In order to achieve the above-described problem, the waveform shaping device of the present invention displays a video signal having a synchronization signal having a portion exceeding the black level of the video, having a frame different from the frame in which the video signal is originally displayed. is displayed on the device, and waveform shaping the sync signal, the waveform shaping apparatus to not be displayed on the display device a synchronization signal, the more time the black level of the image for comparison with the digital values and the black level value of the video signal Extract the period of the black level period of the sync signal that exceeds the black level of the video of the sync signal from the logical product of the black level period detection means to detect and the black level period of the video and the signal that specifies at least the vertical blanking period of the sync signal for waveform shaping And a switch system that replaces the portion of the sync signal that exceeds the black level of the video with the black level of the video. And a portion of the sync signal that is replaced by the switch control means that exceeds the black level of the video by extending and delaying the black level period of the video detected by the black level period detecting means. And a black level period expansion delay unit that is included in a period exceeding the black level of the video extracted by the extraction unit.
[0008]
Desirable forms of the waveform shaping device of the present invention and the display device including the waveform shaping device are the following (1) to (4).
(1) The synchronizing signal exchange period extracting means extracts a period of a portion exceeding the black level of the video of all the synchronizing signals of the video signal.
(2) The synchronizing signal exchange period extracting means extracts a period of a portion exceeding the black level of the video of the synchronizing signal within the vertical blanking period of the video signal.
(3) The synchronizing signal exchange period extracting means extracts the period of the portion exceeding the black level of the video of the synchronizing signal within the period of the vertical drive signal (VD) of the video signal.
(4) The synchronizing signal erasing period extracting means extracts the period of the portion exceeding the black level of the video of every other synchronizing signal within the period of the vertical drive signal (VD) of the video signal.
[0009]
The operation of the above means will be described below.
The black level of the video is detected from the video signal by the black level period detecting means, the detected black level period is extended and delayed by the black level period extending delay means, and the timing is adjusted to adjust the timing. The period of the portion exceeding the black level of the video of the sync signal is extracted by the sync signal exchange period extracting means that takes the logical product of the signal for designating the period of the sync signal for waveform shaping and the switch control means during this period. Thus, the portion of the sync signal that exceeds the black level of the video can be replaced with the black level of the video, and the portion of the video that exceeds the black level can be removed from the sync signal.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the following, as an embodiment, an HDTV video signal is given as a video signal having a synchronization signal having a portion exceeding the black level of the video, and a multi-scan is performed on a 16: 9 image frame in which the video signal is originally displayed. A case where the video signal is displayed in a 4: 3 image frame such as a type monitor will be described, but the waveform shaping device of the present invention, the display device including the waveform shaping device, and the electronic device are of course not limited thereto. This can be applied to a general video signal having a portion exceeding the black level.
[0011]
FIG. 3 shows a waveform shaping device 7 of the present invention. First, the general operation of the waveform shaping device 7 will be described, and the waveform shaping operations (1) to (4) described later will be described in association with each other. The HDTV video signal is input to the waveform shaping device 7 in the form of 10-bit digital data to which a three-level synchronization signal is added by the video output processing circuit 1.
[0012]
The black level is detected by the black level period detection means 2. The black level period detection means 2 is, for example, a digital comparator, which outputs, for example, 1 when the digital data value is larger than the black level value 240 of the HDTV video signal, and outputs 0 when the reverse.
[0013]
When it is detected that the black level is exceeded, the black level period extension delay means 4 extends and delays the period when the black level is exceeded. The black level period extension delay means 4 is configured using, for example, a digital delay circuit 8 and an OR gate 9. At the output of the OR gate 9, for example, a signal that becomes 1 during a period when it is equal to or higher than the black level and becomes 0 after a delay time of the digital delay circuit 8 from the time when it becomes lower than the black level is generated.
[0014]
As described above, the purpose of extending and delaying the black level period by the black level period extension delay means 4 is to change the timing when the part of the synchronization signal to be waveform-shaped is replaced with the black level by the switch control means 6 described later. This is to match. That is, the portion of the synchronization signal to be waveform-shaped of the video signal input to the switch control means 6 is generated by the black level period extension delay means 4, is expanded, and is within the delayed black level period. The timing is adjusted.
[0015]
The synchronization signal exchange period extraction means 5 takes the logical product of the output of the black level expansion delay means 4 and any one of blanking, vertical blanking, and VD, and indicates the period of the portion of the synchronization signal to be replaced with the black level. A signal is generated.
[0016]
The switch control means 6 replaces the portion of the synchronization signal to be waveform-shaped with the black level of the HDTV video signal by a signal indicating the period of the portion of the synchronization signal to be replaced with the black level extracted by the synchronization signal exchange period extraction means 5.
[0017]
On the other hand, the 10-bit digital data is converted into an analog signal by the DAC 3 (digital / analog converter) and input to the switch control means 6, so that the black level of the synchronization signal is exceeded by the signal from the synchronization signal exchange period extraction means 5. An analog HDTV video signal in which the portion is replaced with the black level is obtained from the switch control means 6. The switch 10 is for stopping the operation of the synchronization signal exchange period extraction means 5 and stops when it is connected to the ground B side. At this time, the original HDTV video signal which is not subjected to waveform shaping is obtained from the switch control means 6.
[0018]
In the present embodiment, the switch control means 6 is constituted by an analog device, but it can of course be constituted by a digital device. In this case, the DAC 3 is unnecessary. In this embodiment, since it is assumed that the waveform-shaped HDTV video signal is supplied to the multi-scan monitor as it is, only an example of an analog device is shown.
[0019]
Next, a waveform shaping method will be described with reference to FIGS.
FIG. 1A shows the ternary level synchronization signal of the HDTV video signal shown in FIG. 4 again along with a vertical drive signal (hereinafter referred to as VD) for the following comparison.
[0020]
The method of shaping the waveform of the ternary level synchronization signal of the HDTV video signal is classified into the following (1) to (4). A portion to be waveform-shaped is extracted by the above-described synchronization signal exchange period extraction means 5.
[0021]
(1) FIG. 1B shows an example in which claim 5 is implemented by replacing every other portion of the synchronizing signal exceeding the black level of the video in the VD period with the black level of the video.
[0022]
(2) FIG. 1C shows an example in which the portion of the synchronizing signal within the VD period that exceeds the black level of the video is replaced with the black level of the video.
[0023]
(3) FIG. 2D shows an example in which claim 3 is realized by replacing all portions of the synchronizing signal exceeding the black level of the video in the vertical blanking period with the black level of the video.
[0024]
(4) FIG. 2E shows an example in which claim 2 is implemented by replacing all portions of the video of the sync signal exceeding the black level of the video with the black level of the video.
[0025]
Next, the above-described waveform shaping (1) to (4) will be described in correspondence with the operation of the waveform shaping device 7 with reference to FIGS.
In the case of (1), VD is input to the synchronization signal exchange period extracting means 5 and ANDed with the output of the black level period extension delay means 4, so that the portion of the synchronization signal in the VD period that exceeds the black level is waveform shaped. Is done. At this time, the black level period detection means 2 detects only every other synchronization signal within the VD period. For example, although not shown, the black level period detecting means 2 may be controlled by a pulse generated every other synchronizing signal within the VD period using another logic circuit. As described above, the synchronizing signal exchange period extracting means 5 obtains a signal indicating a predetermined period within the VD period and including a portion exceeding the black level of the synchronizing signal every other synchronizing signal. When the signal is input to the switch control means 6, the waveform shaping described in (1) is performed.
[0026]
In the case of (2), VD is input to the synchronization signal exchange period extraction means 5 and is ANDed with the output of the black level period expansion delay means 4, so that all the synchronization signals in the VD period exceed the black level. Waveform shaping. Since the synchronization signal exchange period extraction means 5 obtains a signal indicating a period within the VD period and including a portion exceeding the black level of all the synchronization signals, if this is input to the switch control means 6, (2). The waveform shaping described above is performed.
[0027]
In the case of (3), since the vertical blanking signal is inputted to the synchronizing signal exchange period extracting means 5 and ANDed with the output of the black level period extension delay means 4, the black level is set for the synchronizing signal in the vertical blanking period. Waveform shaping is performed on the part beyond. Since the synchronization signal exchange period extraction means 5 obtains a signal indicating a predetermined period within the vertical blanking period and including a portion exceeding the black level of the synchronization signal, if this is input to the switch control means 6 (3) The waveform shaping described in the above is performed.
[0028]
In the case of (4), since the blanking signal is inputted to the synchronizing signal exchange period extracting means 5 and is ANDed with the output of the black level period extension delay means 4, the portion of the synchronizing signal within the blanking period exceeds the black level. Is waveform-shaped. Since the synchronizing signal exchange period extracting means 5 obtains a signal indicating a period within the horizontal and vertical blanking periods and including a portion exceeding the black level of the synchronizing signal, if this signal is input to the switch control means 6 ( The waveform shaping described in 4) is performed.
[0029]
The waveform shaping device 7 described above may be installed in an electronic device that sends out an HDTV video signal, or may be provided in a display device such as a multi-scan type monitor. When displaying a video signal, it is possible to prevent a synchronization signal exceeding the black level of the video from being displayed.
[0030]
【The invention's effect】
As described above, according to the waveform shaping device of the present invention, a video signal having a synchronization signal having a portion exceeding the black level of the video is displayed on a display device having an image frame different from the image frame on which the video signal is originally displayed. And the waveform of the synchronization signal can be prevented from being displayed on the display device, and the waveform shaping device of the present invention can be provided in a display device and an electronic apparatus. This is advantageous in that a high-quality image can be obtained.
[Brief description of the drawings]
FIG. 1 is a timing chart for explaining a method of replacing a portion of a synchronizing signal exceeding a black level of a video to be waveform-shaped by a waveform shaping device of the present invention with a black level.
FIG. 2 is another timing chart illustrating a method of replacing a portion of a synchronizing signal exceeding the black level of a video to be waveform-shaped by the waveform shaping device of the present invention with a black level.
FIG. 3 is a configuration diagram showing a schematic configuration of a waveform shaping device of the present invention.
FIG. 4 is a timing chart showing a waveform of a synchronization signal of an HDTV video signal.
FIG. 5 is an explanatory diagram for explaining a screen state when an HDTV video signal having an image frame of 16: 9 is displayed on a multi-scan type monitor having an image frame of 4: 3.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Video output processing circuit, 2 ... Black level period detection means, 3 ... Digital-analog converter, 4 ... Black level period expansion delay means, 5 ... Synchronization signal exchange period extraction means, 6 ... Switch control means, 7 ... Waveform shaping Device, 8 ... digital delay circuit, 9 ... OR gate

Claims (7)

A video signal having a synchronization signal having a portion exceeding the black level of the video is displayed on a display device having an image frame different from the image frame on which the video signal is originally displayed, and the synchronization signal is waveform-shaped, In the waveform shaping device that prevents the signal from being displayed on the display device,
And the black level period detecting means for detecting a period of the black level of more the image on a comparison between the digital value and the black level value of the video signal,
Sync signal exchange period extraction for extracting the period of the portion of the sync signal that exceeds the black level of the video from the logical product of the black level period of the video and the signal that specifies at least the vertical blanking period of the sync signal for waveform shaping Means,
Switch control means that is controlled by the output of the synchronizing signal exchange period extracting means and replaces the portion of the synchronizing signal that exceeds the black level of the video with the black level of the video;
By extending and delaying the black level period of the video detected by the black level period detecting means, the portion of the synchronizing signal that is replaced by the switch control means exceeds the black level of the video. A waveform shaping device, comprising: black level period expansion delay means that is included in a period exceeding a black level of the video extracted by the replacement period extraction means.   2. The waveform shaping device according to claim 1, wherein the synchronization signal exchange period extraction unit extracts a period of a portion of all the synchronization signals of the video signal that exceeds the black level of the video.   2. The waveform shaping apparatus according to claim 1, wherein the synchronization signal exchange period extracting unit extracts a period of a portion of the synchronization signal that exceeds a black level of the video in a vertical blanking period of the video signal.   2. The waveform according to claim 1, wherein the synchronizing signal exchange period extracting means extracts a period of a portion of the synchronizing signal exceeding a black level of the image within a period of a vertical drive signal (VD) of the image signal. Shaping device.   2. The synchronization signal exchanging period extracting means extracts a period of a portion exceeding the black level of the video of every other synchronizing signal within a period of a vertical drive signal (VD) of the video signal. The waveform shaping device described in 1.   A display device comprising the waveform shaping device according to claim 1.   An electronic apparatus comprising the waveform shaping device according to claim 1.

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