JPH0541820A - Television signal processor - Google Patents

Abstract

PURPOSE:To improve the processing accuracy and to simplify the configuration and to reduce the cost in the processor for a television signal in which the analog television signal is once converted into a digital signal, the signal is subjected to ghost elimination processing and Y/C separation processing and the resulting signal is decoded into the analog signal. CONSTITUTION:A variable gain amplifier section 5 is added to a pre-stage of an A/D converter section 1 placed to a pre-stage of a ghost elimination section 2, and a variable gain amplifier section 6 is added to a post-stage of a D/A converter section 4 placed to a post-stage of a Y/C separator section 3, and when an analog television signal being a processing object is a reproduced video signal not including a ghost component, a margin of the D/A converter 2 with respect to its input level is eliminated by increasing the amplifier gain of the variable gain control section 5 to improve the processing accuracy and a level of an analog signal already processed is smoothed by decreasing the amplifier gain of the variable gain control section 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal processing apparatus installed in a television receiver.

[0002]

2. Description of the Related Art Recently, in order to improve the image quality of a television display screen, a received analog television signal is once converted into a digital signal and subjected to various image quality improving processes, and then the processed digital television signal is processed. It is planned to install an image quality improvement processing device for converting the image into an analog television signal and displaying it in the television receiver.

As one of such image quality improving processes, a ghost removing process utilizing a reference signal is planned.
This ghost elimination processing inserts a reference signal with a specific waveform into a specific location such as within the vertical blanking period of the television signal from the transmission side and sends it out.On the receiver side, the reception television signal is converted into a digital signal. A ghost is detected based on a reference signal that has been converted and extracted from this digital television signal and that has undergone ghost distortion and a reference signal that has been held in advance and has no distortion, and this ghost is removed by a digital filter, and then an analog television signal. It is configured to restore to.

As another one of the image quality improving processing, three-dimensional Y
A / C separation is known. In this three-dimensional Y / C separation, an analog television signal is once converted into a digital television signal, and this digital television signal is converted into NT.
The structure is such that the luminance signal and the chrominance signal are separated by utilizing the interlacing and frequency interleaving relationships inherent in the SC standard system and the correlation between adjacent lines and adjacent frames, and then restored to analog signals.

[0005]

In the above ghost removing apparatus, first, the analog television signal A to be processed is
A / D conversion is required, but since the amplitude of this analog television signal fluctuates to a large extent depending on the degree of ghost occurrence, an appropriate margin (for example, 6 dB) is set in the input level range of the A / D converter. Is added to make it wider. However, the same margin is added to the reproduced video signal from the video tape recorder or the laser disk, which does not need to consider the ghost, so that the amplitude of the digital signal is decreased and the processing accuracy is deteriorated.

[0006]

A television signal processing apparatus according to the present invention further includes an A / D conversion section arranged before a digital signal processing section for performing ghost removal and Y / C separation. The input side variable gain amplifying section is installed, and the output side variable gain amplifying section is installed in the subsequent stage of the D / A converting section arranged in the subsequent stage of the digital signal processing section. Is a reproduced video signal supplied from the video reproducing apparatus, a control unit is provided for increasing the gain of the variable gain amplifying unit on the input side and decreasing the gain of the variable gain amplifying unit on the output side.

That is, if the analog television signal to be processed is not a TV signal output from the tuner but a reproduced video signal, since it does not include a ghost component, it falls within the input level range of the A / D converter. There is no need to have a margin for ghosts. Therefore, with respect to the reproduced video signal, the gain of the variable gain amplifying unit on the input side is increased to eliminate the margin of the input level to improve the processing accuracy, and the gain on the input side is probably increased. By reducing the gain, level fluctuations of the processed signal are avoided.

[0008] Further, a ghost removing section in which the analog variable gain amplifying section is arranged before and after and a Y /
A television signal is transferred in digital form with the C separation section, and a variable gain amplification section on the output side is arranged in the latter stage of the Y / C separation section. The operation of the present invention will be described in detail with the following examples.

[0009]

1 is a block diagram showing the configuration of a television signal processing apparatus according to an embodiment of the present invention.
₁ is the input terminal of the analog television signal to be processed,
1 is an A / D conversion unit, 2 is a ghost removal unit, 3 is a Y / C separation unit, 4 is a D / A conversion unit, 5 and 6 are variable gain amplification units, 7
Is a system controller, O ₁ is an output terminal for an analog luminance signal, O ₂ is an output terminal for an analog color signal, and O ₃ is an output terminal for an analog television signal to a video recording device. Further, I ₂ is an input terminal for a control signal indicating whether the analog television signal to be processed is a received television signal output from a tuner or a reproduced video signal output from a reproducing device, and I ₃ is a ghost elimination It is an input terminal of a control signal for instructing invalidation of the function of the section 2.

An analog television signal to be processed, which is supplied from an unillustrated tuner or video reproducing device in the preceding stage to the input terminal I ₁ , is supplied to the A / D converting unit 1 via the variable gain amplifying unit 5, and here the predetermined value is given. It is converted into a digital television signal having a bit width and supplied to the ghost removing section 2. The ghost removing unit 2 extracts a reference signal of a specific waveform (such as a staircase waveform of a specific level superimposed on the pedestal level) inserted in a specific portion of the television signal, for example, a specific line in the vertical blanking period. A ghost is detected based on this and a distortion-free reference signal that is not affected by the ghost, and a ghost removal filter including a transversal filter or the like is controlled according to the detection result to perform ghost removal. Regarding the configuration and operation of the ghost removing unit 2, if necessary, the applicant and the Japan Broadcasting Corporation have previously jointly filed a patent application entitled "Ghost Removing Device", which has already been published. See the specifications of Nos. 20760 to 20762.

The ghost-removed digital television signal output from the ghost removing section 2 is separated into a luminance signal (Y) and a chrominance signal (C) in the Y / C separating section 3 by three-dimensional Y / C separation or the like. After that, it is supplied to the D / A conversion unit 4, where it is restored to an analog luminance signal and color signal. The restored analog luminance signal and chrominance signal are supplied to the output terminals O ₁ and O ₂ connected to the processing circuit of the subsequent stage through the variable gain amplification unit 6 and the synthesizing circuit 8
After being combined with each other, it is supplied to an output terminal O ₃ connected to a video recording device or the like.

The system controller 7 composed of a microprocessor or the like instructs the variable gain amplifying sections 5 and 6 to change the amplification gain based on the binary control signal received from the input terminals I ₂ and I _3. Instructing the ghost removing unit 2 to disable / enable the ghost removing function 2
The value signal is output on the signal line 9. That is, the system controller 7 receives from the input terminal I ₂ a control signal indicating that the signal to be processed supplied to the input terminal I ₁ is the received television signal supplied from the tuner,
In addition, if a control signal input by the user from a switch, a remote controller, or the like is received from the input terminal I ₃ , a high signal is output on the signal line 9. Upon receiving this high signal, the variable gain amplifying section 5 holds the variable gain at the same value as it is, so that the input level of the analog television signal supplied to the A / D converting section 1 has a constant value (for example, 6 dB) margin. To set. On the other hand, the variable gain amplifying section 6 also holds the variable gain as it is. Further, the ghost removing section 2 which receives the high signal on the signal line 9 enables the ghost removing function.

The system controller 7 has an input terminal I ₁
Even if a control signal indicating that the signal to be processed supplied to the receiver is a receiving television signal supplied from the tuner is received from the input terminal I ₂ , a control signal indicating that the ghost removal is not performed is input terminal I ₃ If it is received from, the low signal is output on the signal line 9. Upon receiving this low signal, the variable gain amplification section 5 removes the margin of the input level of the analog television signal supplied to the A / D conversion section 1 by increasing the variable gain by a predetermined value (for example, 6 dB). on the other hand,
The variable gain amplification unit 6 sets the variable gain to a predetermined value (for example, 6d).
B) By lowering, the increase in the amplitude by the variable gain amplifying section 5 is offset, and the amplitude of the processed analog television signal is leveled. Further, the ghost removing section 2 which has received the low signal on the signal line 9 invalidates the ghost removing function by fixing the tap coefficients of the ghost removing filter to all zeros.

The system controller 7 has an input terminal I ₁
If a control signal indicating that the signal to be processed supplied to the input terminal is a reproduced video signal supplied from the video reproducing device is received from the input terminal I ₂ , the signal line is irrelevant to the control signal of the input terminal I _3. A low signal is output on 9 to increase the variable gain of the variable gain amplifying section 5 by a predetermined value (for example, 6 dB) and the variable gain of the variable gain amplifying section 6 by a predetermined value (for example, 6 d).
B) Decrease and disable the ghost removing function of the ghost removing unit 2.

[0015]

The television signal processing apparatus according to the present invention increases the gain of the variable gain amplifying unit on the input side when the analog television signal to be processed is a reproduced video signal containing no ghost component. With this configuration, the margin of the input level to the D / A converter is removed, so that the processing accuracy is improved.

Also, the television signal processing apparatus according to the present invention has a structure in which a variable gain amplifying section is also installed on the output side and the amplification gain is controlled in the opposite direction in conjunction with the input side. Signal level fluctuations are effectively avoided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a television signal processing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

I ₁ Input terminal for analog television signal to be processed I ₂ Input terminal for control signal indicating type of analog television signal to be processed I ₃ Input terminal for control signal for instructing enable / disable of ghost elimination function 1 A / D conversion unit 2 Ghost removal unit 3 Y / C separation unit 4 D / A conversion unit 5 Input side variable gain amplification unit 6 Output side variable gain amplification unit 7 System controller (control unit) O ₁ Processed analog Luminance signal output terminal O ₂ processed analog color signal output terminal

Claims (1)

[Claims] 1. A variable gain amplifier on an input side for amplifying an analog television signal to be processed, an A / D converter for converting the amplified analog television signal into a digital television signal, and the A / D converter. A ghost removing unit that detects and removes a ghost contained in a digital television signal based on a reference signal extracted from a specific portion of a D-converted digital television signal and an undistorted reference signal that is held in advance, and this ghost. A Y / C separation unit that separates the digital television signal from which is removed into a luminance signal and a color signal, and a D / A conversion unit that restores the Y / C separated luminance signal and the color signal into an analog signal, An output-side variable gain amplifier for amplifying the restored analog luminance signal and color signal, and the analog television signal to be processed If it is a reproduced video signal supplied from a video reproducing apparatus, the gain of the variable gain amplifying section on the input side is increased, the gain of the variable gain amplifying section on the output side is decreased, and the function of the ghost removing section is invalidated. And a control section for controlling the television signal processing apparatus.