JP2925798B2 - Television signal processor - Google Patents

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 improvement processes, and then the processed digital television signal is processed. There is a plan to install an image quality improvement processing device in a television receiver for converting the image into an analog television signal for display.

As one of such image quality improvement processes, a ghost removal process using a reference signal is planned.
In this ghost removal processing, a reference signal having a specific waveform is inserted from a transmitting side into a specific place such as in a vertical blanking period of a television signal and transmitted, and the receiver side converts the received television signal into a digital signal. A ghost is detected based on a ghost-distorted reference signal converted and extracted from the digital television signal and an undistorted reference signal held in advance, and the ghost is removed by a digital filter. Is restored.

[0004] As another image quality improving process, a three-dimensional Y
/ C separation is known. The three-dimensional Y / C separation converts an analog television signal into a digital television signal once and converts the digital television signal into an NT signal.
The configuration is such that the luminance signal and the chrominance signal are separated into analog signals using the interlace and frequency interleave relationship inherent to the SC standard system and the correlation between adjacent lines and adjacent frames, and then each is restored to an analog signal.

[0005]

In the ghost eliminator, first, the analog television signal to be processed is A
A / D conversion is required, but since the amplitude of the analog television signal fluctuates to a considerable extent depending on the degree of occurrence of a ghost, an appropriate (for example, 6 dB) margin is set in the input level range of the A / D converter. Is set to be wider. However, the same margin is added to a reproduced video signal from a video tape recorder or a laser disk that does not require consideration for ghost, so that there is a problem that the amplitude of the digital signal is reduced and the processing accuracy is reduced.

[0006]

SUMMARY OF THE INVENTION A television signal processing apparatus according to the present invention is provided further upstream of an A / D conversion section disposed before a digital signal processing section for performing ghost removal and Y / C separation. An input-side variable gain amplifier is provided, and an output-side variable gain amplifier is provided further downstream of the D / A converter disposed downstream of the digital signal processor. Is a playback video signal supplied from the video playback device, a control unit is provided for increasing the gain of the input-side variable gain amplifying unit and decreasing the gain of the output-side variable gain amplifying unit.

In other words, if the analog television signal to be processed is not a TV signal output from the tuner but a reproduced video signal, it does not include a ghost component, so that it is within the input level range of the A / D converter. There is no need to have a margin for ghosts. Therefore, for the reproduced video signal, the gain of the input side variable gain amplifying unit is increased to eliminate the margin of the input level, thereby improving the processing accuracy, and increasing the gain on the input side and possibly increasing the gain on the output side. By reducing the gain, the level fluctuation of the processed signal is avoided.

Further, a ghost removing section in which the analog variable gain amplifying section is disposed before and after, and a Y /
A television signal is delivered in digital form to and from the C separation unit, and a variable gain amplification unit on the output side is arranged downstream of the Y / C separation unit. The operation of the present invention will be described in detail with the following examples.

[0009]

FIG. 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 converter, 2 is a ghost remover, 3 is a Y / C separator, 4 is a D / A converter, 5 and 6 are variable gain amplifiers, 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 recorder. Further, I ₂ is an input terminal of 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 apparatus, and I ₃ is a ghost removal signal. Input terminal of a control signal for instructing the function of the section 2 to be invalid.

[0010] An analog television signal to be processed, which is supplied to an input terminal I ₁ from a tuner or a video reproducing apparatus at a preceding stage (not shown), is supplied to an A / D converter 1 via a variable gain amplifying section 5, where a predetermined signal is supplied. The signal is converted into a digital television signal having a bit width and supplied to the ghost removing unit 2. The ghost removing unit 2 extracts a reference signal of a specific waveform inserted into a specific line of the television signal, for example, a specific line in a vertical blanking period (a staircase waveform of a specific level superimposed on a pedestal level). A ghost is detected based on this and a reference signal that is not affected by the ghost and has no distortion, and a ghost removal filter configured by a transversal filter or the like is controlled in accordance with the detection result, and ghost removal is performed. Regarding the configuration and operation of the ghost removing unit 2, if necessary, the applicant and the Japan Broadcasting Corporation jointly filed an application and have already published an application and published a patent application, entitled “Ghost Removal Device”. Please refer to the specification of Nos. 20760 to 20762 and the like.

The ghost-removed digital television signal output from the ghost removal unit 2 is separated into a luminance signal (Y) and a chrominance signal (C) by a three-dimensional Y / C separation in a Y / C separation unit 3. After that, the signal is supplied to the D / A converter 4, where it is restored to an analog luminance signal and analog color signal. The restored analog luminance signal and chrominance signal are supplied to output terminals O ₁ and O ₂ connected to a subsequent processing circuit via a variable gain amplifying unit 6, and a synthesizing circuit 8.
In it is supplied to the output terminal O ₃ leading to such a video recording device after being synthesized.

A system controller 7 composed of a microprocessor or the like instructs the variable gain amplifiers 5 and 6 to change the amplification gain based on the binary control signals received from the input terminals I ₂ and I ₃ , and Instructs the ghost removal unit 2 to disable / enable the ghost removal function 2
A value signal is output on a signal line 9. That is, the system controller 7 has received a control signal indicating the signal to be processed is supplied to the input terminal I ₁ is received television signal supplied from the tuner from the input terminal I _2,
And if receiving a control signal for performing the ghost canceling input by the user from a switch or a remote controller from the input terminal I _3, and outputs a high signal on the signal line 9. Upon receiving the high signal, the variable gain amplifying section 5 holds the variable gain at the same value, thereby providing a fixed value (for example, 6 dB) margin to the input level of the analog television signal supplied to the A / D conversion section 1. Set. On the other hand, the variable gain amplifier 6 also holds the variable gain at the same value. Further, the ghost removing unit 2 that has received the high signal on the signal line 9 enables the ghost removing function.

The system controller 7 has an input terminal I ₁
Also signal to be processed being fed is not receiving the control signal indicating that the received television signal supplied from the tuner from the input terminal I _2, the input control signal indicating not to perform ghost cancellation terminals I ₃ , A low signal is output on the signal line 9. The variable gain amplifying unit 5 that has received the low signal removes the margin of the input level of the analog television signal supplied to the A / D converter 1 by increasing the variable gain by a predetermined value (for example, 6 dB). on the other hand,
The variable gain amplifier 6 sets the variable gain to a predetermined value (for example, 6d
B) By reducing the amplitude, the increase in the amplitude by the variable gain amplifying unit 5 is canceled, and the amplitude of the processed analog television signal is leveled. Further, the ghost removing unit 2 that receives 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 the control signal indicating that the signal to be processed supplied to the input terminal I is a reproduced video signal supplied from the video reproducing apparatus is received from the input terminal I ₂ , the signal line regardless of the control signal of the input terminal I ₃ 9 to output a low signal to increase the variable gain of the variable gain amplifier 5 by a predetermined value (for example, 6 dB) and increase the variable gain of the variable gain amplifier 6 by a predetermined value (for example, 6 d).
B) Lowering and disabling the ghost removal function of the ghost removal unit 2.

[0015]

According to the television signal processing apparatus of the present invention, if the analog television signal to be processed is a reproduced video signal containing no ghost component, the gain of the variable gain amplifier on the input side is increased. Thus, since the input level margin for the D / A converter is removed, the effect of improving processing accuracy is achieved.

Further, the television signal processing apparatus according to the present invention has a configuration in which a variable gain amplifying unit is also provided 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 the drawings]

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

[Explanation of symbols]

I ₁ Input terminal of analog television signal to be processed I ₂ Input terminal of control signal indicating the type of analog television signal to be processed I ₃ Input terminal of control signal for instructing activation / inactivation of ghost removal function 1 A / D conversion section 2 Ghost removal section 3 Y / C separation section 4 D / A conversion section 5 Variable gain amplification section on input side 6 Variable gain amplification section on output side 7 System controller (control section) O ₁ Processed analog output terminals of the output terminal O ₂ processed analog color signal of the luminance signal

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 5/14-5/217

Claims (1)

(57) [Claims] An input-side variable gain amplifier 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; A ghost removing unit that detects and removes a ghost included in the digital television signal based on a reference signal extracted from a specific portion of the D-converted digital television signal and a pre-held distortion-free reference signal; A Y / C separation unit that separates the digital television signal from which the luminance has been removed into a luminance signal and a chrominance signal, a D / A conversion unit that restores the Y / C separated luminance signal and chrominance signal into an analog signal, An output-side variable gain amplifier that amplifies the restored analog luminance signal and color signal, and the analog television signal to be processed In the case of a reproduced video signal supplied from a video reproducing device, the gain of the variable gain amplifier on the input side is increased and the gain of the variable gain amplifier on the output side is reduced, and the function of the ghost removing unit is disabled. A television signal processing device, comprising: