JPS58108874A - Ghost eliminating device - Google Patents

Abstract

PURPOSE:To eliminate a ghost normally even in a transient state such as powerup operation of a television receiver, by sampling a detection signal of a ghost in a prescribed section and thus obtaining the reference voltage of the weighting circuit of a transversal filter. CONSTITUTION:The capacitor 22b of a bias circuit 22 for outputting a reference voltage is charged stepwise through a swich circuit 21 by a signal from an amplifier 14 at intervals of a vertical synchronizing signal. The output signal of this bias circuit 22 charged stepwise is supplied as the reference voltage to other- side terminals for determined weighting coefficients of weigting circuits 81, 82- 8n. At this time, voltages of average signals outputted from analog accumulators 181, 182-18n and the reference voltage outputted from the bias circuit 22 are both charged stepwise with the same time constant at intervals of the vertical synchronizing signal to eliminate a ghost without great deviation in weighting coefficient from a video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ghost removal device suitable for use in removing ghosts in a television receiver aircraft, and in particular, to remove normal pressure ghosts even in a transient state such as when the power is turned on. Currently, it is possible to remove ghosts from the video signal by processing the video signal output from the video detection circuit as shown in Figure 1 using a differential transversal filter. A ghost removal device has been proposed.

Hereinafter, an example of this ghost removal device will be explained with reference to FIGS. 1 to 5. Good morning.

In FIG. 1, a received signal from an antenna (1) is supplied to a video detection circuit (4) through a tuner (2) and a video intermediate frequency amplifier (3), where the video signal is detected.

This video signal is supplied to a synthesizer (6) via a delay circuit (5) corresponding to the preceding ghost detection period I/C, and a canceling signal simulating a ghost from a transversal filter, which will be described later, is added to this synthesizer. is supplied to the container (6),
A video signal from which ghosts have been removed is obtained from the synthesizer (6) at an output terminal (7).

Further, the video signal obtained from the video detection circuit (4) is weighted by the circuit (81) which constitutes the transparsal filter.
)? (82) s・・・・・・s (8n)
The visual circuit (9)K is supplied through the circuit (9)K. This delay circuit (
9) is one in which a plurality of stages (n) of delay elements each having a sampling period of, for example, l Q (ns) are connected, and n input terminals are provided between each stage.

On the other hand, the video signal from the synthesizer 16) is supplied to one input terminal of the subtraction circuit (1G).

Furthermore, the Eirin Iki signal from the Eirin detection circuit (4) is supplied to the synchronization separation circuit Ql)K, and the separated vertical synchronization signal is supplied to the standard waveform forming circuit 61JK, and the leading edge of the vertical synchronization signal v
A standard waveform approximated by a unit step function of E is formed. This standard waveform is supplied to the other input terminal of the subtraction circuit 01.

The signal from this subtraction circuit (1) is supplied to a differentiation circuit (1) to detect ghosts.

As a signal for detecting and measuring ghosts, a signal that is included in a standard television signal and is not affected by other signals for as long as possible, such as a vertical synchronization signal, is used. That is, as shown in Fig. 2 1□, the leading edge VE of the vertical synchronizing signal and the ±
(1/2)H (H is horizontal period) is not affected by other signals.Therefore, from the signal of this period, standard waveform formation open circuit α
A ghost detection signal is detected by subtracting the standard waveform from the subtracting circuit a and differentiating the subtracted signal from the subtracting circuit a.

For example, the phase difference with the composite video signal due to the delay time τ! (=ω0
τ, however, ω. is the Eirin carrier angle frequency at the high frequency stage) is 4
When a 5° ghost is included, a video signal with a waveform as shown in FIG. 3A appears. On the other hand, this video signal is differentiated and the polarity is inverted to obtain a ghost detection signal having a differential waveform shown in FIG. 3B, and this differential waveform can be approximately regarded as an impulse response of a ghost.

Then, the differential waveform ghost detection signal appearing from the differentiating circuit 03 is sent to the demultiplexer 0!1 via the amplifier 04).
9. Similar to the delay circuit (9), this demultiplexer cIS has a plurality of delay elements connected in units of sampling periods, and n taps are derived from each interval.@Output of each tap Switch circuit (161) 4 (16z) ---
.

(16n).

Further, the vertical synchronization signal from the synchronization separation circuit αυ is supplied to the gate pulse generator 0η, and a gate pulse corresponding to the end of the (1/2) H section from the leading edge WE of the vertical synchronization signal is formed. Switch circuit (leh
), (16g) *・== t (16n) is turned on〇This switch circuit (161) * (162)
*'-"" The signals from t (16n) are sent to analog accumulators (181) and (182) +...t(
18n) this analog accumulator (181)
The signals from t (182) t..., (18n) are sent to buffer circuits (191) and t (192), respectively.
--w (19n) via 2 weighting circuit (8i)
*(82).

. . . The weighting of e (8n) is supplied to one signal input terminal which determines the coefficient. Also, fixed bias circuit-
The bias from is weighted by the circuits (81), (82), .
...”*(8n) weighting is supplied to the other signal input terminal which determines the coefficient.Then, the analog accumulator (18
1) , (182) *=...

Subtraction is performed between the signal from (18n) and the bias from fixed bias circuit (a), and weighting is performed by circuit (81) t
(82).

=・-e (8n) weighting coefficients are determined・These weightings are circuits (81), (8g), t...
*The output signals of (8n) are respectively supplied to each tap of the delay circuit (9) to form a cancellation signal.@Then, this cancellation signal is supplied to the synthesizer (6).

In this way, the delay circuit (9) and the weighting circuit (81) *
(8t).

. . . t(8n)K, a transversal filter is constructed, and ghosts are removed. In this case, after detecting the leading edge VE of a certain vertical synchronization signal and the waveform distortion in the ±(1/2) H section before and after it and adjusting the weighting coefficient,
Therefore, in order to reduce the unerased ghost, an analog accumulator (181) I (182)...* (
However, in a transient state such as when the power is turned on for the ghost removal device configured in this way, the power is turned on at time tQ as shown in Figures 4 and 5. Then, the bias from the fixed bias circuit (7) is applied to a switch (16x), (
16g), · Song ·, (16n) is obtained by charging the capacitor, so it becomes an exponential waveform and reaches a steady state at time t2 after a relatively long period of time. During the period tQ-1fi, which is this transient state, the weighting is such that no coefficient can be obtained if the circuit (8n) is normally powered; There was a drawback that the weighting was no longer performed, and the operation was performed as if there was a ghost even when there was no ghost.In view of this, the present invention has the disadvantage that it operates normally even in a transient state such as when the power is turned on. This is an attempt to propose something that can remove ghosts.

Hereinafter, an embodiment of the ghost removal device of the present invention will be explained with reference to FIGS. 6 and 7.
In the figures, parts corresponding to those in FIGS. 1 to 5 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In Fig. 6, @ indicates a switch circuit, one contact of this switch circuit (2) is connected to the output @ of amplifier 04), and the other contact of this switch circuit (2) is connected to the reference voltage resistor (2
2m) and a capacitor (22b) to ground via a series circuit, the standard waveform from the standard waveform forming circuit (13) is supplied to a second gate pulse generator, and this second gate pulse generator - The ≠−11 gate pulse from the switch circuit 6! is supplied as a signal for controlling this switch circuit (c), and this gate pulse causes the switch circuit Q
]) is turned on.

This second gate pulse generator is a standard waveform forming circuit 0
When the standard waveform shown in FIG. 7AK is supplied from the source, an equalization pulse P just before the vertical synchronization signal PI as shown in FIG. 7B is generated.
2, the time Tl1 is, for example, 10 to 25 (us
), the gate pulse φ (pulse width: 10 (ns)
) to occur. The value of this delay time Tl is designed to supply the capacitor (22b) with a flat portion of the waveform outputted from the amplifier αa, as shown in FIG. 7CK, in which the amplitude is small and uniform. In addition, the pulse width of the gate pulse φ is determined by the analog accumulator (181
) + (''82) *--t When the time constant of (18n) and the time constant of resistor (22a) and capacitor (22b) K are set to be the same, the demultiplexer (1
It is equal to the delay time of one stage of delay elements of 51, and is set as follows.

Furthermore, the weighting circuit (81) * (82
) is -...* The weighting of (8n) is 0, which is supplied to each signal input terminal that determines the coefficient.The other configurations are the same as those shown in FIG. 1 above.

According to the ghost removal device having such a configuration, in a transient state such as when the power is turned on, the analog accumulator (18i)
t (182) t-""5 (18n), the signal from the demultiplexer α9 for each vertical synchronization signal is sent to a switch circuit (16□).

(16t) *−・−・−(16n) is charged in a stepwise manner to I,N. The analog accumulator (181) t (18z) *=-s (
18n) is weighted by a circuit (81),
The weights (8), . . . (8n) are supplied to one terminal that determines the coefficients. - 10,000, the capacitor (22b) of the bias circuit (a) that outputs the reference voltage is also charged in a stepwise manner with the signal from the amplifier I via the switch circuit (2) for each vertical synchronization signal. The weighting circuit (81
) s (8*) s...” The weighting of t(8n) is 0, which is supplied as a reference voltage to the other terminal that determines the coefficient.
At this time, the analog accumulator (18l) t(18g).

......* The average signal voltage output from (18n) and the reference voltage output from the bias circuit are both charged in a stepwise manner for each vertical synchronization signal with the same time constant. When weighting signals, the coefficients do not shift significantly, and when there is no ghost, the corner does not act as if there were a ghost, and ghosts are removed.

As described above, according to the present invention, ghosts can be normally removed even in a transient state such as when the power is turned on.Incidentally, according to the present invention, screen blurring can be eliminated even in a transient state. The time until 1 minute ago,
I was able to mourn for about 10 seconds.

Further, FIGS. 8 and 10 show other embodiments of the ghost removal device of the present invention. In FIGS. 8 and 10, parts corresponding to those in FIGS. 1 to 5 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

The Monoke shown in FIGS. 8 and 9 generates two gate pulses φ and φ' from the second gate pulse generator, and supplies the gate pulses φ to the switch circuit HeC similar to that shown in No. 68 above. , gate node φ′ is amplifier a4
supply to. This gate pulse φ' is generated so that the gate pulse φ is located within the pulse width of the gate pulse φ' as shown in Figure DK.Then, the amplifier I is connected to the second gate pulse generator 2) Gate pulse φ from
When ' is supplied, a flat signal of a predetermined level is output as shown in FIG. 9CK without being affected by the ghost detection signal from the differentiating circuit I.

Also in the embodiments shown in FIGS. 8 and 9, a signal having an average value of the signal from the amplifier I can be supplied to the bias circuit (2) K by the gate pulse φ, and the bias circuit ( 2) Reference voltage from analog accumulator (18t)s
Since the voltage of the average signal from (lh)s..., (18n) can be changed with the same time constant, it is possible to Even in a transient state of the times, it is possible to maintain a near-normal state K (W/I11* of Gorsuji).

In the above example, the pulse width of the gate pulse φ output from the third gate pulse generator was set equal to the delay time of one stage of the delay element of the demultiplexer 09. However, by increasing the pulse width of the gate pulse φ from the second gate pulse generator (E) (from B to 3' in FIG. 10), the signal C from the amplifier Oa changes. By supplying more of the voltage to the bias circuit (a), it is possible to form the reference voltage at a more average level. In this case, by increasing the pulse width, the time constant of the bias circuit (A) becomes smaller, so by increasing the resistor (22a) that is involved in the time constant of the bias circuit (A), the time constant of the bias circuit (A) is increased. to other analog accumulators (181) t(182)...t (18n
) so as to match the time constant of

In the above-described embodiment R, the gate pulse φ output from the second gate pulse generator (E) is matched to a flat portion where the amplitude of the signal output from the differentiating circuit 03 is small and uniform. However, the subtraction circuit is 0.
It goes without saying that the gate pulse φ may be generated where the dynamic range of the differential circuit is saturated. Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and that various other configurations can be taken without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a ghost removal device, FIGS. 2 to 5 are diagrams for explaining FIG. 1, and FIG. 6 is a configuration diagram showing an embodiment of the ghost removal device of the present invention. Fig. 7 is a line diagram for explaining Fig. 6, Fig. 8 is a configuration diagram showing another embodiment of the present invention, Fig. 9 is a line diagram for explaining Fig. 8, and Fig. 10 is a diagram for explaining Fig. 6. The figure is a diagram for explaining another embodiment of the present invention. (A) is a switch circuit, (A) is a bias circuit, a wire is a second gate pulse generator, and a wire is a buffer circuit. Figure 2 VF Figure 4 '4''S 51 nonj 6; Figure 9 +oN

Claims (1)

[Claims] A ghost is detected using a predetermined section of the combined picture signal, and in this ghost detection No. 48, the weighting coefficient of the transversal filter is adjusted to form a cancellation signal that simulates the ghost, and the ghost is detected. In a ghost removal device that removes the ghost by combining a cancellation signal with the 4r-fti video signal, the weighting of the transversal filter is performed using the reference voltage of the circuit as the ghost detection signal. A ghost removal device is characterized in that the ghost removal device is obtained by sampling from a predetermined section of