JPS6222308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ghost reduction device.

As shown in FIG. 1, the conventional ghost reduction device supplies a video signal after detection to one input terminal of an adder A having two input terminals, and sends the output of the adder A to a distribution device. The signal is input to B and divided into two, and the distributed output from one output terminal is supplied to a correction device C that performs delay correction, in-phase correction, and quadrature correction, and the signal corrected by this correction device C is sent to an addition device A. The feedback system is closed by supplying the signal to the other input terminal of the distribution device B, and the signal with reduced ghosting is taken out from the other output terminal of the distribution device B and supplied to the television receiver as a video signal. In this case, the adjustment of the ghost mitigation device is
This was done manually to reduce ghosting while watching the reproduced image on the television receiver.

A specific circuit diagram of this ghost reduction device is shown in FIG. When a detected video signal containing a ghost signal is applied to the terminal T ₁ , this video signal is supplied to the base of the transistor Q ₁ through the coupling capacitor C ₁ . This transistor _Q1 and transistor
Q ₂ and resistors R ₁ , R ₂ , and R ₃ constitute an adder circuit, a ghost cancellation signal is supplied to the base of transistor Q ₂ , and the video signal and ghost cancellation signal are combined. This composite signal is
After passing through resistor R ₄ , transistor Q ₃ and resistor
An inverting amplifier consisting of R ₅ and R ₆ separates the signal into two paths and outputs it. Note that resistors R ₇ , R ₈ , R ₉ , and R ₁₀ are used to provide base bias to transistors Q ₁ and Q ₂ .

One output of the inverting amplifiers Q ₃ , R ₅ , and R ₆ is supplied to a delay line DL that can adjust the delay time through an emitter follower circuit consisting of a transistor Q ₄ and a resistor R ₁₁ and a resistor R ₁₂ . The output of this delay line DL passes through an emitter follower circuit consisting of a resistor _R13 , a transistor _Q5 , and a resistor _R14 , and then is divided into two paths. The outputs of the emitter follower circuits Q ₅ and R ₁₄ are supplied through a high-pass filter consisting of a coupling capacitance C ₂ and resistors R ₁₅ and R ₁₆ to a phase synthesizer consisting of a transistor Q ₆ and resistors R ₁₇ and R ₁₈ .
The resistances R _{17 and} R ₁₈ of the phase synthesizer Q ₆ , R ₁₇ , and R ₁₈ are set to the same value to obtain a signal with an inverted phase. These two signals are combined by a variable resistor VR ₁ through a coupling capacitor C ₃ , and the composite signal is taken out from the movable terminal of the variable resistor VR _1. By selecting the position of this movable terminal, the polarity and amplitude of the composite signal can be controlled. You can choose freely. Also, Emitsuta follower circuit Q ₅ , R ₁₄
The output of is supplied through a high-pass filter consisting of a coupling capacitor C ₄ and resistors R ₁₉ and R ₂₀ to a phase synthesizer consisting of a transistor Q ₇ and resistors R ₂₁ and R ₂₂ .
Since the time constants of the high-pass filters C ₄ , R ₁₉ , and R ₂₀ are selected to be large, they can transmit up to the DC component, and the resistors R ₂₁ and R ₂₂ of the phase synthesizer Q ₇ , R ₂₁ , and R ₂₂ A signal with an inverted phase is obtained by making them the same value. Both these signals are connected through a coupling capacitance C ₅ to a variable resistor VR ₂
The composite signal is taken out from the movable terminal of the variable resistor VR ₂ , and the polarity and amplitude of the composite signal can be freely selected by selecting the position of this movable terminal. The output from the movable terminal of this variable resistor VR ₂ and the output from the movable terminal of the aforementioned variable resistor VR ₁ are connected through coupling capacitances C ₆ and C _7, respectively, to transistors Q ₈ and Q ₉ and resistors R ₂₃ , R ₂₄ , and R. In addition to the adder circuit consisting of ₂₅ and synthesized, this adder circuit Q ₈ ,
The outputs of Q ₉ , R ₂₃ , R ₂₄ , and R ₂₅ are connected to the aforementioned adder circuit Q ₁ ,
Q ₂ , R ₁ , R ₂ , R ₃ are added to the base of transistor Q ₂ through a coupling capacitor C ₈ to close the feedback system. Note that resistors R ₂₆ , R ₂₇ , R ₂₈ , and R ₂₉ are used to provide base bias to transistors Q ₈ and Q ₉ .

In this way, by closing the feedback chain, a ghost-reduced video signal is taken out from the collector of transistor Q ₃ of the inverting amplifier Q ₃ , R ₅ , R ₆ and fed back to transistor Q ₁₀ and the resistor.
It is output from terminal _T2 through an emitter follower circuit consisting of _R30 and coupling capacitance _C9 .

This ghost reduction device has no problem with the reproduced image when the ghost is reduced to its maximum, but in the process of adjusting to reduce the ghost, the delay time and
The amplitude of the ghost reduction processing signal changes significantly due to the deviation of the in-phase component and the quadrature component, and when performing ghost reduction adjustment using the image reproduced from this ghost reduction processing signal, the contrast of the screen changes significantly, making adjustment extremely difficult. Ta. This situation is shown in FIG. Figure 3A shows a video signal,
FIG. 3B shows a ghost reduction processed signal in the process of correcting the ghost signal superimposed on the video signal to reduce the ghost. FIG. 3B shows how the amplitude of the ghost reduction processed signal becomes larger than the normal amplitude due to the addition of the ghost signal and the correction signal due to the large deviation of the correction signal. During this adjustment process, parts of the screen may become dark or white.
Adjustment was extremely difficult.

Therefore, an object of the present invention is to provide a ghost reduction device that allows easy ghost reduction adjustment.

The ghost reduction device of the present invention includes a variable voltage gain device for inputting a video signal including a ghost signal, an adder to which the output of the variable voltage gain device is added to one input terminal, and an output of the adder. a first distribution device that distributes; a second distribution device that distributes the output of one of the first distribution devices;
a correction device for delaying and amplitude correcting the other output of the first distribution device and adding it to the other input terminal of the addition circuit to reduce ghost signals; A peak value is detected, and only when the peak value exceeds a predetermined amplitude that causes a darkening or whitening phenomenon on the screen, the gain of the voltage gain variable device is decreased or increased in accordance with the increase or decrease in the peak value. and a peak value detection device for limiting the amplitude of the output signal of the second distribution device.

According to the present invention, the ghost signal is reduced by delaying the input video signal including the ghost signal, adjusting the delay time, amplitude, and polarity, and then adding it to the original input video signal. The device detects the peak value of the output signal of the adding device, and uses the peak value detection output only when the peak value exceeds a predetermined amplitude that causes dark spots or white spots on the screen. The gain of the input video signal is controlled to be small and the output signal of the adding device is limited so as not to exceed a predetermined amplitude.
The gain of the input video signal is not controlled until the peak value of the output signal of the adder exceeds a predetermined amplitude, so that the amplitude of the desired signal does not change due to adjustments for ghost reduction, and This makes it easier to understand the screen changes during ghost reduction adjustment, making adjustment work easier. Furthermore, by limiting the amplitude when it exceeds a predetermined amplitude, it prevents image distortion and makes it easier to adjust ghost reduction. can.

A block diagram of a ghost reduction device according to an embodiment of the present invention is shown in FIG. That is, this ghost reduction device supplies a video signal to one input terminal of a variable voltage gain device D, and outputs the output of this variable voltage gain device D to one side of an adder circuit A similar to the ghost reduction device shown in FIG. In addition to the input terminal of the distribution device B, the distribution output from the other output terminal of the distribution device B is sent to the distribution device E.
In addition, the distributed output from one output terminal of the distribution device E is supplied to the peak value detection device F, and the detected potential of the peak value detection device F is applied to the other input terminal of the voltage gain variable device D as a variable gain potential. The feedback system is closed and the distribution output from the other output terminal of the distribution device E, that is, the ghost reduction processed signal is controlled so that it does not exceed a predetermined amplitude.

Next, the specific circuit of the variable voltage gain device D will be explained in the fifth section.
This will be explained with reference to the diagram. This voltage gain variable device D
In this case, a video signal is applied to the terminal _T3 , a detection potential outputted from the peak value detection device F is applied to the terminal _T4 as a variable gain potential, and a video signal is applied to the terminal _T5.
Output is retrieved from . The video signal applied to terminal T ₃ is connected to the transistor whose base bias is given by battery V ₁ and resistors R ₃₁ and R ₃₂ .
Out of Q ₁₁ and Q ₁₂ , it is supplied to the base of transistor Q ₁₁ via a coupling capacitor C ₁₀ and amplified there.
In addition, the variable gain potential applied to terminal T ₄ is smoothed by capacitor C ₁₁ and then
Supplied to the base of Q ₁₃ and Q ₁₄ . At this time,
The output is taken out from a terminal _T5 connected to the common collector of transistors _Q14 and _Q15 . In this case, a base bias is applied to the common base of transistors Q ₁₅ and Q ₁₆ by battery V ₂ and resistor R ₃₃ , and when the potential of the common base of transistors Q ₁₃ and Q ₁₄ becomes higher than the potential of battery V ₂ , Terminal _T5
The output from transistor Q ₁₃ ,
When the potential of the common base of Q ₁₄ becomes lower than the potential of battery V ₂ , the output from terminal T ₅ increases. In addition,
R ₃₄ , R ₃₅ , R ₃₆ and R ₃₇ are resistors.

Next, a specific circuit of the distribution device E will be explained with reference to FIG. The signal applied to terminal T ₆ is connected to a terminal connected to an emitter follower circuit consisting of transistor Q ₁₇ and resistor R ₃₈ and an emitter follower circuit consisting of transistor Q ₁₈ and resistor R ₃₉ , respectively.
It is distributed and output from T ₇ and T ₈ .

Next, the specific circuit of the peak value detection device F will be explained in the seventh section.
This will be explained with reference to the diagram. Transistors Q ₁₉ and Q ₂₀ constitute a differential amplifier, and this transistor
A transistor is connected to the common emitter of Q ₁₉ and Q ₂₀ .
Q ₂₁ is connected to a constant current source consisting of resistor R ₄₀ and battery V ₃ . Further, a base bias is applied to the transistor Q ₁₉ by the battery V ₄ and the resistor R ₄₁ , and a signal applied to the terminal T ₉ and passed through the coupling capacitor C ₁₂ is applied to the base. In addition, the base of the transistor Q ₂₀ has a battery
_V5 is connected. Therefore, the transistor
The peak value of the signal applied to the base of Q ₁₉ is
When the potential exceeds _V5 , it is detected and a detection potential is generated at the collector of transistor _Q19 , which is output from terminal _T10 . Note that _R42 is a resistance.

The ghost mitigation device of this embodiment delays an input video signal containing a ghost signal with a correction device C,
In a ghost signal reduction device that reduces a ghost signal by adjusting the delay time, amplitude, and polarity and then adding it to the original input video signal in an adder A, the peak of the output signal of the adder A The peak value is detected by the peak value detection device E, and only when the peak value exceeds a predetermined amplitude that causes dark spots or white spots on the screen,
The peak value detection output is used to control the gain of the input video signal to be reduced by the variable voltage gain device D, so that the output signal of the adding device A is limited so as not to exceed a predetermined amplitude. ,
The gain of the input video signal is not controlled until the peak value of the output signal of the adder A exceeds a predetermined amplitude, so that the amplitude of the desired signal does not change due to adjustment for ghost reduction; To facilitate adjustment work by making it easy to understand screen changes during ghost reduction adjustment, and to prevent image disturbance by limiting the amplitude when it exceeds a predetermined amplitude, thereby making it easier to adjust ghost reduction. I can do it.

As described above, according to the ghost reduction device of the present invention, the input video signal including the ghost signal is delayed, the delay time, amplitude, and polarity are adjusted, and then the ghost signal is added to the original input video signal. In a ghost reduction device designed to reduce the signal, the peak value of the output signal of the adding device is detected, and only when the peak value exceeds a predetermined amplitude that causes dark spots or white spots on the screen. , using the peak value detection output to control the gain of the input video signal to be small,
Since the output signal of the adder is configured to be limited so that it does not exceed a predetermined amplitude, the gain of the input video signal is not controlled until the peak value of the output signal of the adder exceeds the predetermined amplitude, and the desired signal is The amplitude of the image does not change due to the adjustment for ghost reduction, making it easier to understand the screen changes when adjusting the ghost reduction, making the adjustment work easier. By limiting this, it is possible to prevent image distortion and make it easier to adjust ghost reduction.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional ghost reduction device, Fig. 2 is its specific circuit diagram, Fig. 3 is also an explanatory diagram of its operation, Fig. 4 is a block diagram of an embodiment of the present invention, and Figs. FIG. 7 is a specific circuit diagram of each main part. A...addition device, B...distribution device, C...correction device,
D...Voltage gain variable device, E...Distribution device, F...Peak value detection device.

Claims (1)

[Claims] 1. A variable voltage gain device for inputting a video signal including a ghost signal; an adding device to which the output of the variable voltage gain device is added to one input terminal;
a first distribution device that distributes the output of the adding device; a second distribution device that distributes one output of the first distribution device; and a delay and amplitude correction for the other output of the first distribution device. A correction device is added to the other input terminal of the adding circuit to reduce the ghost signal, and a peak value of one output of the second distribution device is detected and the peak value is applied to the other input terminal of the adding circuit to reduce the ghost signal. A peak value that limits the amplitude of the output signal of the second distribution device by decreasing or increasing the gain of the voltage gain variable device in accordance with the increase or decrease in this peak value only when the amplitude exceeds a predetermined amplitude that would cause a whitening phenomenon. A ghost mitigation device comprising a detection device.