JPS60206290A - Correcting device of profile in vertical direction - Google Patents

Abstract

PURPOSE:To reduce substantially a circuit size by utilizing only one 1H delay line instead of using two 1H delay lines as conventional and by constituting in such a way that preshoots and overshoots are added in good balance. CONSTITUTION:An input signal (a) is delayed by means of a delay line 33 by 1H-tau and furthermore by means of a delay element 35 by zero. An output signal c1 of the delay line 33 passes through a low-pass filter 34, and delayed by a time tau and by 1H with respect to the input signal (a). An output signal of an adder 36 is multiplied by -1/A1 by means of an inversion amplifier 38. The output signal of an adder 40 is inverted by an inverter 41 and fed back to an adder 32. After repetition of these actions, a signal (e), a signal (h) and a signal (j) can be obtained at an output terminals of the adder 36, the adder 40 and of an amplifier 42, respectively. The signals (e) and (j) are added in an adder 39, and a signal (k) where preshoots are overshoots are simultaneously added to its vertical profile can be obtained at an output terminal 43.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a vertical contour correction device in an image projection device such as a color television receiver, and the present invention relates to a vertical contour correction device for an image projection device such as a color television receiver. The present invention relates to a vertical contour correction device having a so-called comb filter function capable of separating a luminance signal and a carrier color signal from a color television signal.

[Technical background of the invention and its problems]

The video signal bandwidth of the television transmission and reception system is 4.
．． 2 Ml (limited to z, high-frequency components beyond this are not transmitted, and 2. In principle, there is an accent etc. in the fine parts and edge parts of the original picture, and the sharpness of the projected TV image is This is a contributing factor to the decline.

Therefore, in order to improve the sharpness, it is known to use printing and overshooting before and after the edge portions of the video signal. This will be explained with reference to FIG.

When a video signal that changes in a stepwise manner as shown in FIG. 1(a) is manually generated, a positive contour 111i signal can be obtained by performing first or second differentiation of the signal. Figure 1(b) shows an example of a second-order differential waveform, and this waveform signal (b) is used as the input signal (a).
As shown in Figure 1(C), a signal with overshoot is obtained.
Contour correction is performed.

However, such contour correction has the following problems.

In other words, to obtain the second-order differential waveform mentioned above.

Since a circuit using an inductor, a capacitor, and a resistor is usually used, there is a disadvantage that basically only the outline of the reproduced image can be corrected in the horizontal direction.

In a television transmitting/receiving system, the image sending side converts the gray dust of two pixels into a temporally continuous electrical signal by scanning the image, and the image receiving side synchronizes with the resolution scanning of the image on the sending side. It is designed to reproduce a two-dimensional image by assembling and scanning the images. Therefore, a signal from one horizontal scanning period (IH) before is required for contour correction in the vertical direction of the image.

In order to obtain the above-mentioned pre-IH signal, a CCD (Charg
An example of a conventional device that performs vertical contour correction using such a delay circuit will be described with reference to FIGS. 2 to 4.

FIG. 2 shows a block diagram of the vertical contour correction circuit.

This figure shows an example of a vertical contour correction device that is capable of applying an oversheet and a preset at the same time. In FIG. 2, (11) is an input terminal for a video signal.

(12), (13) are IH delay lines, (14)
), (16) is an inverting amplifier, (15) is an amplifier,
(i7) is an addition circuit.

(18) respectively indicate signal output terminals.

The operation of the circuit shown in FIG. 2 will be explained with reference to FIGS. 3 and 4. In Figure 3, (10) shows an image on a display unit such as a cathode ray tube, and as shown in Figure 3, the image is vertically ``black'', ``white'', and ``black''. Consider the case where a picture signal is received.

A video signal waveform as shown in FIG. 4(a) is applied to the input terminal (11) in FIG. 2. In this figure (a), (S) indicates a horizontal synchronizing signal, and Y) indicates a picture signal component.

One horizontal scanning period is represented by (IH). This signal waveform (a) is transmitted to the IH by the IH delay line (12).
The result is delayed and becomes as shown in FIG. 4(b). Furthermore, the IH delay is caused by the IH delay 2-in (13), as shown in FIG. 4(C). Further, FIG. 4(d) shows a signal waveform obtained by adding the output of the amplifier (15) and the output of the inverting amplifier (14),
Figure 4 (, e) shows the output of the amplifier (15) and the inverting amplifier (
The signal waveform obtained by adding the output of 16) is shown. As a result, the output of the adder circuit (17), that is, the signal waveform of the output terminal (18) has waveforms (b) and (d).

(e) is added, resulting in a result with preshoot and overshoot as shown in FIG. 4(f).

Vertical contours can be corrected.

However, in the vertical contour correction circuit as shown in Fig. 2, 2
The disadvantage is that the circuit requires several IH delay lines, and if it is constructed from a delay circuit such as a CCD, the circuit becomes large-scale.

It is also well known that in color television transmission and reception systems based on the NTSC system, the voice signal is multiplexed and transmitted by frequency interleaving as a carrier chrominance signal on the high-frequency component of the luminance signal. be. That is, the solid line in FIG. 5(A) shows the frequency spectrum of the luminance signal, which has peaks at horizontal frequency (fH) intervals. On the other hand, the fugitive color signal (its center frequency is 35
8 MHz) is interpolated on the high-frequency side of the luminance signal so as to have a peak between the frequency spectra of the luminance signal when viewed in one frequency spectrum, as shown by the dotted line.

In order to reproduce a color image from a color television signal having such a signal form, it is necessary to separate the luminance signal and the carrier color signal and extract them. FIG. 6 shows a circuit for the separation and extraction. That is, the sixth
In the figure, (21) is a signal input terminal to which a color television signal is supplied.

(22) is a delay line that provides a delay of one horizontal scanning period, (23) and (24) are delay lines (22)
(25) is a luminance signal output terminal; (25) is a luminance signal output terminal; (25) is a luminance signal output terminal; (25) is a luminance signal output terminal;
6) is the 1st general color feed I1''? output terminal.

This FIG. 6 selectively passes a large portion of the value vector of the luminance signal and the carrier chrominance signal.

This constitutes a so-called comb filter system, and the comb filter characteristics are shown in FIG. 5(B). still,
Since FIGS. 5 and 6 are generally well known, further details will be omitted, but the system shown in FIG. 6 and the vertical contour correction circuit shown in FIG. 2 described above can be combined to separate luminance signals. It is also possible to have K perform vertical contour correction, but I
Since two H delay lines are used to provide overshoot and preshoot, the circuit becomes large-scale and has the disadvantage of being uneconomical.

[Purpose of the invention]

In view of the above points, the present invention has an extremely small circuit scale,
It is an object of the present invention to provide a vertical contour correction device that can add a preshoot and an automatic comb shoot to a vertical contour and also has a comb filter function.

[Summary of the invention]

The present invention is a means for combining a first signal and a second signal, the first combining means being provided with a signal from a color television signal source as the first signal.

At the output end of this first combining means, 1. a delay device for connecting second delay means in series and outputting a signal obtained by delaying the first signal by one horizontal scanning period to an output terminal of the second delay means;

Differential mixing means for differentially and summatively mixing the signal delayed by the delay device and the first signal, respectively;
as well as Japanese mixed means.

connected to the output terminal of the first delay means of the delay device, and having substantially the same signal delay time as the second delay means;
A low-pass filter that separates and extracts low-frequency luminance signal components.

and second combining means for combining the output of the summative mixing means and the output of the low-pass filter at a predetermined ratio as signals of relatively opposite polarity.

The output of this second synthesizing means is synthesized with the output of the summative mixing means as a contour correction signal having a predetermined ratio and polarity, and the synthesized output is subjected to printing, z-cutting, and overshooting. and a third combining means for obtaining a brightness signal.

The vertical contour correction device is provided with a feedback circuit network for supplying the output of the second combining means as a second signal with a polarity opposite to that of the contour correction signal to the first combining means.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings from FIG. 7 onwards. First of all, FIG. 7 shows an example, (
31) is a signal input terminal to which a color television signal is supplied, and this input terminal (31) is connected to one input end of the signal synthesizing means 1, for example, an adding circuit (32); The output end is connected to the input end of a delay line (33) having a delay time of (IH-'7). The output end of this delay line (33) is connected to the input end of the low-pass filter 5 (34) and the input end of the delay element (35).

The delay time of this delay element (35) is (c'7).

The delay time of the low pass filter (34) is chosen to be the same as the signal delay time caused by the low pass filter (34), ie the delay time of the low pass filter (34) is also (τ). Also low frequency 7 small wave device (34)
The cutoff frequency of is selected to be approximately 2Maz.

The output terminal of the delay element (35) is connected to the sum r of the signal, to one input terminal 16 of the 1M combining means 1, for example, an adder circuit (36I), and to one input terminal of the 1M combining means 2, for example, the subtracting circuit (37). The other input terminals of the addition circuit (36) and the subtraction circuit (37) are respectively connected to the signal input terminal (31).The addition circuit (36)
The output terminal of is an inverting amplifier (38) and signal combining means.

For example, one input terminal of an adding circuit (39) is connected to each input terminal of a liquid adding circuit (40), and the output terminal of this adding circuit (40) is connected to the adding circuit via an inverter (41). (32) and further connected to the other input end of the adder circuit (39) via an amplifier (42). and addition circuit (39)
The output terminal of is connected to the luminance signal output terminal (43).

The output terminal of the rt bi circuit (37) is connected to the carrier color signal output terminal (44).

In this example, the amplifier (38) has an amplification factor of (-"), and the amplifier (42) has an amplification factor of (A2).

Next, the operation of the circuit shown in FIG. 7 will be explained with reference to FIGS. 8 to 10. The signal supplied to the signal input terminal (31) is connected to (LH-”G by the delay line (33)
Since the delay element (35) further delays the signal by (7), the output terminal of the delay element (35) receives a signal delayed by exactly IH with respect to the input signal of the input terminal (31). is obtained. Therefore, in the addition circuit (36) and the subtraction circuit (37), the input terminal (31
) and the output terminal (44) of the IH delay block 37)
A carrier color signal is obtained.

In addition, in the NTSC system, the color subcarrier (3.58MH2) is modulated with the color signal to transmit the color signal (see Fig. 8).
2 in the 4.2MHz band as shown in the spectrum a)
．． They overlap between 1Maz and 4.2Maz.

In other words, the carrier color signal is centered at 3-58 muz and the upper part is 4.
Below 2 MHz, it exists only within the range of 2.1+Jt+z. On the other hand, the cut-off frequency of the low-pass filter (34) in Fig. 7 is selected to be approximately 2 MHz, so that the low-pass filter (34) in Fig. 8(b)
A luminance signal component is extracted from the output of this low-pass filter (34) as shown in FIG. Therefore, in the circuit of FIG. 7, when the signal is 2MH2 or more, it becomes the same as that of FIG. 6, and exhibits a so-called comb filter function.
Separation of the carrier chrominance and luminance signals is achieved.

Next, vertical contour correction will be explained with reference to FIG. 9. Note that each point a to k shown in FIG.
This shows that signals labeled a-k in the figure appear. In FIG. 9, (a) is the signal input terminal (31
), but for the sake of convenience, signals similar to those shown in FIG. 4(a) above are shown with the exception of the synchronization signal omitted.

One horizontal scanning period is expressed as IH. This input signal (
a) Delay line (3) via Lt adder circuit (32)
3), it is delayed by (IH-T), resulting in the waveform shown in FIG. 9 (C1), and is further supplied to the delay element (
35), it is delayed by (2), and in the end it is delayed by (2) in Figure 9 (dl
), the signal (d) is delayed by 11 (delayed) with respect to the input signal (a).
l) and input signal (a) are added, and this addition circuit (36
) A signal having a waveform as shown in FIG. 9 (el) is obtained at the output end of the circuit.

Also, the output signal (C1) of the delay line (33) is delayed by the time σ) by passing through the low-pass filter (34), and is delayed by IH with respect to the input signal (a), similar to the aforementioned signal (dl). , (fl) (shown with the same waveform as di). Further, the output signal (el) of the adder circuit (36) is multiplied by -π (for example, by -U) by an inverting amplifier (38) to obtain a waveform as shown in FIG. 9 (gl). This signal (gl) and the above-mentioned signal (fl) are sent to the next stage adding circuit (
40), and a signal as shown in FIG. 9 (hl) is obtained at its output terminal.

This signal (hl) is inverted by an inverter (41) to become the signal shown in FIG. 9(i), and is fed back to the adder circuit (32). Therefore, this adder circuit (32
), a signal shown in FIG. 9(bl) is obtained by adding the signals (a) and (i). This signal is again delayed by the delay line (33) and the delay element (35), resulting in the IH delayed signal as shown in FIG. 9 (d2). This signal (d2) and the input signal (a) are connected to the adder (36
), resulting in a signal waveform like (C2), and the output of the low-pass filter (34) has a waveform (f2) similar to the signal (d2).
). Also, the signal (e2) is -
The signal (g2) is multiplied by 1, and the above-mentioned signal (f2) and this signal (g2) are added in the adder circuit (40) to produce the signal (
h2) is obtained. This signal (h2) is then inverted by the inverter (41) to become (12), and the signal (
h2) is multiplied by A2 (for example, three times) by the amplifier (42), resulting in a waveform as shown in FIG. 9 (j2).

The signal (12) is fed back to the adder circuit (32) again.

As a result of repeating this operation, the addition circuit (36)
A signal with a waveform as shown in FIG. 10(e) is obtained at the output terminal of the adder circuit (40), a signal as shown in FIG. At the end is the first
A signal like that shown in Figure 0 (D) is obtained.

And the signal (e) in Fig. 10 and (D is the adder circuit (39)
As a result, the output terminal (43) shown in Fig. 10 (
As shown in k), a vertical contour corrected signal with preshoot and overshoot added at the same time is obtained.

9. The relative amplitude ratio of the signal for contour correction (Fig. 10 j) to the original signal is determined by the inverting amplifier (38) or the amplifier (42).
It can be arbitrarily designed by appropriately selecting the degree of amplification, etc.

Thus, in the circuit of Figure 7 there is only one delay line (
33) can be used to add both preshoot and overshoot.

Next, a modification of the present invention will be described with reference to FIGS. 11 and 12. Note that the same parts as in FIG. 7 are denoted by the same reference numerals.

FIG. 11 shows an inverter (
41), and the output of this inverter (42) is fed back to the other input terminal of the adder circuit (32), and further fed to the other input terminal of the adder circuit (39) via an inverting amplifier (45). It was designed to be supplied. in this case,
The amplification factor of the rotary amplifier (45) is (-A2).

Also, Figure 12 shows the low-pass filter (34) and adder circuit (40).
An inverter (41) is inserted between one input terminal of the adder circuit (40), and an amplifier (46) is inserted between the output terminal of the adder circuit (36) and the other input terminal of the adder circuit (40).
) is fed back as it is to the adder circuit (32), and is also fed back to the adder circuit (39) via a 2-inverting amplifier (45).
The pressure is applied to the other input end of the In this case, the amplification factor of the amplifier (46) is (Wρ), and the amplification factor of the 1-inverting amplifier (45) is (-A2).
In Figure 2, the output of the inverter (41) is (f) in Figure 9.
2), the output of the amplifier (46) corresponds to the inverted signal of (g2) in FIG.
The output of 40) corresponds to the signal of (12) in FIG. Therefore, the output of the inverting amplifier (45) is the 10th
Corresponds to figure (j2).

Thus, the circuit of the present invention not only has a comb filter characteristic and can separate a luminance signal and a carrier color signal, but also can correct vertical contours by adding preshoot and overshoot. Furthermore, only one IH delay line (actually, an IH-7 delay line) is required, and the scale of the two circuits can be reduced. In addition, the delay element (35) is C
Since ordinary small-sized delay element parts can be used without relying on large-scale circuits such as CDs, it does not pose a great burden.

Furthermore, it goes without saying that the present invention is not limited to the above-mentioned circuit example, but can also realize various modifications without departing from the scope of the claims, and is not limited to the example shown in the two figures. As described above, according to the present invention, preshoot and overshoot can be added to the nine vertical contours in a well-balanced manner by using only one IH delay line, instead of requiring two IH delay lines as in the conventional case. This makes it possible to significantly reduce the circuit scale.

Furthermore, it is possible to separate the luminance signal and the carrier color signal without impairing the effect of the conventional comb filter.

Correction of vertical contours may also be possible.

[Brief explanation of drawings]

Fig. 1 is a signal waveform diagram for explaining the operation of a conventional contour correction device using a second-order differential circuit, Fig. 2 is a circuit diagram showing an example of a conventional vertical contour correction device, Figs. The figure is an explanatory diagram of a television image and a signal waveform diagram of each part used to explain the operation of the circuit in Figure 2. Figure 5 is a diagram showing the frequency spectrum and comb filter characteristics of an NTSC color television signal. Figure 6 is a diagram showing the comb filter characteristics. 7 is a circuit diagram showing an embodiment of the vertical contour correction device of the present invention, and FIG. 8 is a frequency spectrum of a composite video signal in the NTSC system, and a low-pass filter used in the present invention. FIG. 9 is a diagram showing the characteristics of the vessel. FIG. 10 is a signal waveform diagram of each part for explaining the operation of the circuit of FIG. 7, and FIGS. 11 and 12 are circuit diagrams showing modifications of the circuit of FIG. 7. 32, 36. 39. 40...Addition circuit. 37・・・・・・・・・・・・Subtraction circuit. 33...-...Delay line. 34・・・・・・・・・Low pass filter. 35・・・・・・・・・Delay element. 38.45...Inverting amplifier. 42.46...Amplifier. 41・・・・・・・・・Inverter agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2 Figure 4 10 Figure 5 Figure 6') d @ Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12

Claims (1)

[Claims] A color television signal source. means for combining a first signal and a second signal, the first combining means being provided with a signal from the color television signal source as the first signal; At the output end of this first combining means, 1. A delay device which connects second delay means in series and obtains at the output end of the second delay means a signal obtained by delaying the signal at the output end of the first combining means by one horizontal scanning period. Differential mixing means for differentially and summatively mixing the signal delayed by the delay device and the first signal, respectively;
as well as Japanese mixed means. connected to the output terminal of the first delay means of the delay device, and having substantially the same signal delay time as the second delay means;
A low-pass filter for separating and extracting low-frequency luminance signal components. and second combining means for combining the output of the summative mixing means and the output of the low-pass filter at a predetermined ratio as signals of relatively opposite polarity. The output of this second combining means is combined with the output of the summative mixing means as a contour correction signal having a predetermined ratio and polarity, and a luminance signal with preshoot and overshoot is obtained as the combined output. and a third synthesis means for. A vertical contour correction device comprising: a feedback circuit that supplies the output of the second synthesis means as a second signal to the first synthesis means with a polarity opposite to that of the contour correction signal.