JPH03120964A - Television receiver and ghost eliminating device - Google Patents

Abstract

PURPOSE:To eliminate ghost efficiently by providing an equalizing quantity detection control means. a channel selection start detection means setting the equalizing quantity to a prescribed value, and a lock detection means controlling a detection equalization start period of the equalizing quantity detection control means. CONSTITUTION:Since a channel selection start detection means 110 sets equalization quantity controlled by an equalizing quantity detection control means 107 to a prescribed value after a television receiver starts its channel selection, such a defect as malfunction of ghost elimination caused during the channel selection of a television broadcast is reduced. A lock detection means 111 starts detecting the equalizing quantity controlled by an equalizing quantity control means 107 after the television receiver finishes the channel selection and its detection output is made stable. Thus, malfunction of ghost elimination caused by the channel selection of the TV broadcast and waste of equalizing detection controlled till the detection output is made stable are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television receiver, and particularly to a television receiver having a ghost removal function.

[Conventional technology]

In a television receiver, when radio waves arriving directly from the transmitting antenna (desired waves) and radio waves reflected from buildings, etc. (reflected waves) are simultaneously received by the receiving antenna, an image due to the desired waves and the reflected waves are generated. A so-called ghost occurs, where the image appears shifted.

Such ghosts are a major factor in deteriorating the image quality of television receivers, and various methods have been attempted in the past to remove or prevent ghosts.

For example, as described in Japanese Patent Publication No. 62-4894, a group of delay elements is set up, and after selecting a signal delayed by a time corresponding to a ghost from the group of delay elements, an amplitude corresponding to the level of the ghost is selected. This can be removed by adjusting the gain polarity.

How to measure ghost delay time.

As described in Japanese Patent Publication No. 61-60638, it is known to measure the time between the edge of a vertical synchronizing pulse of a television signal and the edge of the vertical synchronizing pulse due to a ghost.

In addition, studies are underway to transmit the signals necessary for accurately detecting the delay time and amplitude of ghosts from broadcasting stations, and it is necessary to insert a reference signal for ghost removal control within the vertical retrace period of normal video signals. Regarding October 19, 1987
Caliber Electronics published by Japan, pages 213 to 225
It is shown in ``Broadcasting by inserting reference signal for ghost canceller control into television signal'' on page 1. Furthermore, in that paper, the gain polarity of the signal from the delay element group is adjusted.
An algorithm for controlling the tap coefficients of so-called transversal filters is also presented.

[Problem to be solved by the invention]

The above-mentioned conventional technology is based on a ghost cancellation device for a television receiver and a ghost cancellation reference signal (hereinafter referred to as OCR) for removal.
However, no consideration was given to the use of the television receiver, such as the channel selection operation, and there were problems such as the possibility of ghost removal malfunctioning.

An object of the present invention is to solve the above-mentioned problems, to provide a television receiver that controls the channel selection operation and ghost removal operation of the television receiver, has fewer malfunctions, and has the function of efficiently removing ghosts. It is on offer.

(Means for Solving the Problem) In order to achieve the above object, an equalization amount detection control means for detecting and controlling the equalization amount of the waveform equalization means of the television receiver, and an equalization amount detection control means for setting the equalization amount to a certain value. This is achieved by providing a tuning start detection means for detecting the start of tuning, and a lock detection means for controlling the equalization start timing detected by the equalization amount detection control means.

[Effect]

The tuning start detection means sets the equalization amount controlled by the equalization amount detection control means to a certain constant value when the television receiver starts the tuning operation.

It is possible to reduce ghost removal malfunctions that occur during a television broadcast channel selection operation.

The lock detection means detects when the television receiver completes the channel selection operation. After the detection output is stabilized, the equalization amount controlled by the equalization amount detection control means is started to be detected, so that ghost removal malfunctions caused by channel selection operations of television broadcasting and the like can be avoided until the detection output becomes stable. The waste of the controlled equalization detection operation can be reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a television receiver according to the invention. FIG. 1(a) is a block diagram, and FIG. 1(b) is a waveform diagram for explaining the operation.

101 is an antenna, 102 is a tuner, 103 is a channel selection control circuit, 104 is a video signal detection circuit, 105 is a ghost removal circuit, 106 is a waveform equalization circuit, 1o7 is an equalization amount detection control circuit, and 108 is a video signal processing circuit. , 109 is a display device, 110 is a tuning start detection circuit, and 111 is a lock detection circuit.

Further, 151 to 155 are waveforms.

A television signal input from an antenna 101 is amplified and frequency-converted by a tuner 102. Tuning is performed by the tuning control circuit 103 during frequency conversion of the tuner 102. The video signal is detected by the video signal detection circuit 1.4 and a video signal is obtained. This video signal is subjected to ghost removal by a ghost removal circuit 105, signal processing by a video signal processing circuit 108, and then provided to a display device 109. The ghost removal circuit 5 includes a waveform equalization circuit 106 and an equalization amount detection control circuit 107. The operation of the ghost removal circuit 105 will be explained with reference to FIGS. 2 to 4.

When selecting a channel for television broadcasting, there may be a situation where operating the ghost removal circuit 105 during channel selection may cause interference such as malfunction. Here, explanation will be made using FIG. 1(b). As shown in waveform 151, when the channel is selected from channel A to channel B at time T1, the channel selection operation shown in waveform 152 is detected by the channel selection start detection circuit 1 at time T1.
At step 10, the equalization amount detected as shown by a waveform 154 and controlled by the equalization amount detection control circuit 107 is set to a certain constant value after the start of channel selection is detected. Thereafter, at time T4, as shown by a waveform 153, the television receiver completes the channel selection operation etc. by the lock detection circuit 111, the carrier wave regeneration PLL circuit of the video signal detection circuit 104 is locked, and the detection output becomes stable.
Thereafter, at time T5, the equalization amount detection control controlled by the equalization amount detection control circuit 107 is started as shown by a waveform 155.

According to this embodiment, since the tuning start detection circuit 110 and the lock detection circuit 111 can initialize and start the operation control of the ghost removal circuit 105, ghosts can be removed during tuning operation of television broadcasting, etc. This has the effect of reducing malfunctions and efficiently removing ghosts. Also. In the case of general television receivers, the time required for channel selection differs depending on the amount of channel spacing before and after channel selection, so starting equalization detection control after lock detection is important depending on the size of the channel spacing. You can set the time according to the situation, and it has the effect of removing ghosts more efficiently.

The basic operation of ghost removal will be explained using FIGS. 2 and 3.

FIG. 2 shows an example in which a transversal filter is used as the waveform equalization circuit 106, and FIG. 3 is a waveform diagram for explaining the same.

201 is an input terminal, 202 is an output terminal, 203 is a tapped delay line, 204a to 204e are tap amplifier circuits, 205 is an adder circuit, and 206a to 206e are control inputs that control each coefficient of the tap amplifier circuits 204a to 204e. Terminal, 207 is a subtraction circuit, τ is a tapped delay line 203
301 is an input waveform, 302 is a ghost compensation waveform, and 303 is an output waveform.

When a video signal as shown in the input waveform 3゜1 is input to the input terminal 201, in which an in-phase ghost with a delay time of 3τ and an amplitude A is added to the desired signal, 3. Gain of the tap amplifier circuit 204c connected to the tap (hereinafter referred to as tap gain)
Let be A. At this time, since the signal shown in the compensation waveform 302 is obtained as the output of the adder circuit 205, the subtracter circuit 205
By subtracting the ghost compensation waveform 302 from the input waveform 301 input in step 7, a signal from which the ghost has been removed as shown in the output waveform 303 is obtained at the output terminal 202.

FIG. 4 shows a block diagram of a configuration example of a ghost removal device using a correlation algorithm.

401 is an input terminal, 402 is an A/D conversion circuit, 403 is a transversal filter, 404 is an output waveform memory,
405 is an arithmetic circuit, 406 is a reference waveform memory, 407 is a tap gain memory, 408 is a D/A conversion circuit, and 409 is an output terminal. In this example, the equalization amount detection control circuit 10
7 is an output waveform memory 404. Arithmetic circuit 405. It consists of a reference waveform memory 406 and a tap gain memory 407.

A video signal input from an input terminal 401 is converted into a digital signal by an A/D conversion circuit 402, ghosts are removed by a transversal filter 403, and then the video signal is converted to a digital signal by an A/D conversion circuit 402.
It is converted into an analog signal by the A conversion circuit 408 and output from the output terminal 409. Transversal filter 40
The output signal No. 3 is stored in the output waveform memory 404, and a calculation circuit 405 performs a correlation calculation between the data in the output waveform memory 404 and the data previously stored in the reference waveform memory 406. By repeating this action,
The data in the output waveform memory 404, which is the output signal of the transversal filter 403, and the data in the reference waveform memory 406 stored in advance can be brought close to each other.
Eventually the ghost can be removed.

FIG. 5 shows another embodiment of the television receiver according to the present invention. FIG. 5(a) is a block diagram, and FIG. 5(b) is a waveform diagram for explaining the operation. 111 is a lock detection circuit; 5
01 is a lock detection circuit, 502 is a lock detection monitoring circuit, and 551 to 555 are waveforms. In addition, the same symbols as in FIG. 1 indicate the same functions.

The difference from FIG. 1 is that the output signal of the lock detection circuit 501 is input to the lock detection monitoring circuit 502, and the carrier wave regeneration PLL circuit of the video signal detection circuit 104 is locked for a certain period of time or more. amount detection control circuit 1
This is the point at which detection of the equalization amount controlled by 07 starts. As a result, as shown by waveform 553, a locked state was detected once at time T4, but it lasted only until time T5, so at time T7 after the locked state was detected at time T6, as shown by waveform 555. Start detecting the equalization amount.

According to this embodiment, in addition to the effect shown in FIG. 1, there is an effect that malfunctions in ghost removal caused by frequent channel selection operations of television broadcasting can be prevented in advance.

FIG. 6 shows another embodiment of the television receiver according to the present invention. FIG. 6(a) is a block diagram, and FIG. 6(b) is a waveform diagram for explaining the operation.

601 is a video signal input terminal, 602 is a synchronization detection circuit, 6
03 is a video signal output terminal, 604 is a video recording and reproducing device, and 651 to 653 are waveforms. In addition, the same symbols as in FIG. 1 indicate the same functions.

In this embodiment, the video signal input to the ghost removal circuit 105 is a signal from another video signal device such as a VTR. Therefore, the video recording and reproducing device 60 such as a VTR
Even if the video signal input to the ghost removal circuit 105 is disturbed due to channel selection in step 4, the tuning start detection circuit 110 and the lock detection circuit 111 cannot be used as shown in FIG. By detecting the synchronization signal of the video signal input to 105, it is possible to know whether the video signal is disturbed or stabilized.

Regarding the selection of television broadcasts, etc.

This will be explained using FIG. 6(b). When a channel is selected from channel A to channel B at time T1 as shown in waveform 651, the synchronization signal is no longer detected by synchronization detection circuit 602 at time T2 as shown in waveform 652, and the equalization amount detection control circuit 107 controls the channel. The equalization amount is set to a certain constant value after the start of tuning is detected. Thereafter, at time T3, when the television receiver completes the channel selection operation and the video signal becomes stable, the synchronization detection circuit 602 detects a synchronization signal, as shown by waveform 653 at time T4. Then, the equalization amount detection control controlled by the equalization amount detection control circuit 107 is started.

According to this embodiment, since the synchronization detection circuit 602 can initialize and start the operation control of the ghost removal circuit 105, ghosts can be removed during channel selection of television broadcasting, etc., as in FIG. This has the effect of reducing malfunctions and efficiently removing ghosts.

FIG. 7 shows another embodiment of the television receiver according to the present invention. FIG. 7(a) is a block diagram, and FIG. 7(b) is a waveform diagram for explaining the operation. 602 is a synchronization detection circuit, 70
1 is a synchronization detection circuit, 702 is a synchronization detection monitoring circuit,
751 to 753 are waveforms. Otherwise, the same symbols as in FIG. 6 indicate the same functions.

The difference from FIG. 6 is that the output signal of the synchronization detection circuit 701 is input to the synchronization detection monitoring circuit 702, and only when the synchronization signal of the video signal is continuously detected for a certain period or more, the equalization amount detection control circuit 107 This is the point at which the detection of the equalization amount controlled by is started. As a result, as shown by waveform 752,
Although the synchronization signal was detected once at time T3, it lasted only until time T4, so as shown by a waveform 753, the detection of the equalization amount is started at time T6 after the synchronization signal was detected at time T5.

According to this embodiment, in addition to the effect shown in FIG. 6, there is an effect that malfunctions in ghost removal caused by frequent channel selection operations of television broadcasting can be prevented in advance.

FIG. 8 shows another embodiment of the television receiver according to the present invention.

801, 802, 803, 804, 805 are switching circuits, 806 is a control circuit, and the others shown in FIGS.
The same symbols as in the figure indicate the same functions.

In this embodiment, it is considered that the video signal is input to the ghost removal circuit 105 after being switched between the video signal from another video signal device such as a VTR and the signal received from the video signal detection circuit 1o4. In the case of a signal from the video signal detection circuit 104, the television receiver knows whether the video signal has been disturbed or stabilized due to a tuning operation, etc. by the signals from the tuning start detection circuit 110 and the lock detection circuit 111. VTR
In the case of a video recording/playback device 604 such as the synchronization detection circuit 6
02, the synchronization signal of the video signal input to the ghost removal circuit 105 is detected, and it is known whether the video signal is disturbed or stabilized.

The switching circuit 801 and the control circuit 806 select the signal from the video signal detection circuit 104 and the video signal input terminal No. 48 from the video recording/reproducing device 604 such as a VTR and apply it to the ghost removal circuit 105 . Switching circuits 802 and 803 switch the control circuit 806 in accordance with the switching.
, 804, the outputs of the tuning start detection circuit 110, the lock detection circuit 111, or the synchronization detection circuit 602 are selected and applied to the equalization amount detection control circuit 107. Also,
By control circuit 806 and switching circuit 805.

The signals of the ghost removal circuit 105, the video signal detection circuit 104, and the video signal input terminal 601 are selected, and the display device 10
It can be displayed on 9.

According to this embodiment, when the signal applied to the ghost removal circuit 105 is a television broadcast from a video recording and reproducing device such as a VTR, the synchronization detection circuit 602 initializes and starts the operation control of the ghost removal circuit 105. In the case of television broadcasting from the video signal detection circuit 104, the tuning start detection circuit 110 and the lock detection circuit 111
Since the operation control of the ghost removal circuit 105 can be initialized and started, the operation control of the ghost removal circuit 105 can be performed during the channel selection operation of the television broadcast, whether it is directly receiving the television broadcast or indirectly receiving it from a video recording and reproducing device such as a VTR. This has the effect of reducing ghost removal malfunctions and efficiently removing ghosts.

〔Effect of the invention〕

According to the present invention, since it is possible to control the channel selection operation and the ghost removal operation of the television receiver, it is possible to effectively remove ghosts with fewer malfunctions.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram showing an embodiment of the television receiver of the present invention, FIG. 1(b) is a waveform diagram for explaining the operation of the embodiment of the television receiver of the present invention, and FIG. Figure 2 is a block diagram of an example using a transversal filter as a waveform equalization circuit, Figure 3 is a waveform diagram for explaining the waveform equalization circuit, and Figure 4 is a configuration example of a ghost removal device using a correlation method algorithm. Block diagram, Fig. 5(a), Fig. 6(a)
). 7(a) and 8 are block diagrams showing other embodiments of the television receiver according to the present invention, FIG. 5(b),
FIGS. 6(b) and 7(b) are waveform diagrams for explaining the operation of another embodiment of the tenovision receiver according to the present invention. 101...Antenna, 102...Tuner,
103... Tuning control circuit, 104... Video signal detection circuit, 105... Ghost removal circuit, 106... Waveform equalization circuit, 107... Equalization amount detection control circuit, 108... Video signal processing circuit, 109... Display device, 110... Channel selection start detection circuit, 111.111, 501... Clock detection circuit, 50
2...Lock inspection monitoring circuit. 601...Video signal input terminal, 602.602,701-...Synchronization detection circuit, 603.
...Video signal output terminal, 604...Video recording and reproducing device. 702...Synchronization detection monitoring circuit, 801.802,803,804.805=--switching circuit, 806...Control circuit・Collection 3 Diagram

Claims (1)

[Scope of Claims] 1. In a television receiver having a waveform equalization means for ghost removal etc., an equalization amount detection control means for detecting and controlling the equalization amount of the waveform equalization means; a tuning start means for detecting that the machine is in a tuning state and setting the equalization amount of the equalization amount detection control means to a certain constant value; and a carrier wave regeneration means for synchronous detection used for detecting the video signal. 1. A television receiver comprising lock detection means for detecting a locked state of a certain PLL circuit and controlling start of detection control of said equalization amount detection control means. 2. Claim 1 characterized in that the lock detection means is provided with lock detection monitoring means for monitoring whether the locked state of the lock detection means continues for a certain period of time or more.
Television receiver as described. 3. In a television receiver having a waveform equalization means for ghost removal etc., an equalization amount detection control means for detecting and controlling the equalization amount of the waveform equalization means, and an input means to which a video signal is input; When the synchronization signal of the video signal is detected and the synchronization signal cannot be detected, the equalization amount of the equalization amount detection control means is set to a certain constant value, and after the synchronization signal is detected, the equalization amount detection control means detects the synchronization signal. A television receiver comprising synchronization detection means for controlling start of control. 4. The television receiver according to claim 3, wherein the synchronization detection means includes synchronization detection and monitoring means for monitoring whether the synchronization signal is detected for a certain period of time or more. 5. In a ghost removal device having a waveform equalization means for ghost removal etc., an equalization amount detection control means for detecting and controlling the equalization amount of the waveform equalization means, an input means to which a video signal is input, and an image When the synchronization signal of the signal is detected and the synchronization signal cannot be detected, the equalization amount of the equalization amount detection control means is set to a certain constant value, and after the synchronization signal is detected, the detection control of the equalization amount detection control means is performed. 1. A ghost removal device comprising: synchronization detection means for controlling start. 6. The ghost removal apparatus according to claim 5, wherein the synchronization detection means includes synchronization detection and monitoring means for monitoring whether the synchronization signal is detected for a certain period of time or more. 7. In a television receiver having a waveform equalization means for ghost removal etc., an equalization amount detection control means for detecting and controlling the equalization amount of the waveform equalization means, and the television receiver being in a channel selection state. a lock state of a PLL circuit which is a carrier wave reproducing means for synchronous detection used for detecting a video signal; lock detection means for detecting and controlling the start of detection control of the equalization amount detection control means; input means to which a video signal is input; detecting a synchronization signal of the video signal; synchronization detection means for setting the equalization amount of the equalization amount detection control means to a certain constant value and controlling the start of detection control of the equalization amount detection control means after a synchronization signal is detected; and a signal to be applied to the waveform equalization means. A television receiver comprising control means for selecting the channel selection start means and lock detection means or synchronization detection means as a control signal for the equalization amount detection control means. 8. Claim 7, characterized in that the lock detecting means is provided with lock detection monitoring means for monitoring whether the locked state of the lock detecting means continues for a certain period or more.
Television receiver as described. 9. The television receiver according to claim 7, further comprising synchronization detection and monitoring means for monitoring whether the synchronization signal is detected for a certain period of time or more as the synchronization detection means.