KR790001791B1 - Automatic peaking apparatus - Google Patents

Abstract

An apparatus for processing TV video signsls, including luminance, chrominance and color burst signal components, was composed of; a source of video signals, a signal delaying meansm, a plurality of signal coupling means for developing a plurality of delayed video signals, a means for deriving a bandwidth determining signal, a means for deriving a control signal from a predetermined portion of the video signals, and a means for deriving an output signal from at least a resultant signal.

Description

Automatic picking device

1 is a schematic diagram showing a general apparatus of a color television receiver using an embodiment of the present invention to process a brightness signal.

2 is a graph showing amplitude versus frequency transfer characteristics associated with signals generated in the embodiment shown in FIG.

3 is a schematic diagram showing another embodiment of the present invention that can be used in the general apparatus of the color television receiver shown in FIG. 1 for processing a brightness signal.

4 is a graph showing amplitude versus frequency transfer characteristics associated with signals generated in the embodiment shown in FIG.

5 is a schematic diagram schematically illustrating a general apparatus of a color television receiver using another embodiment of the present invention for processing chromaticity signals.

FIG. 6 shows yet another embodiment of the present invention that can be used in the general apparatus of the color television receiver shown in FIG. 5 for processing chromaticity signals.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for shaping the amplitude versus frequency transfer characteristics of a television signal processing apparatus, and more particularly to an apparatus for automatically controlling the peaking characteristic of a television signal processing apparatus. In the brightness channel of a color television receiver, the amplitude of the high frequency components of the brightness signal is peaked to improve the transient response of the receiver, while the chromatic and audio signals that may appear in the brightness channel and may cause uncomfortable patterning of the viewer. It is preferable to attenuate.

It is also desirable to extract the chroma signal from, for example, the composite video signal as part of the color demodulation process in the chroma channel. It is also preferable to automatically adjust the amplitude of the high frequency signal component in response to the control signal. For example, the transmission channel tends to attenuate the high frequency signal more than the low frequency signal. Therefore, it is desirable to automatically adjust the high frequency signal amplitude according to an undesirable amount of attenuation of the signal. Therefore, the chroma channel includes an automatic chroma control (ACC) device for controlling the signal amplitude in the frequency range of the chroma signal according to the amplitude reduction of the reference signal or the high frequency test.

The color burst signal included in the composite video signal indicates color reference phase information and is commonly used as a test signal for ACC.

Concentrated parameter circuits are known for shaping the amplitude versus frequency transfer characteristics of a signal processing system to increase the amplitude of a signal in a particular frequency range while attenuating the signal outside that range. Automatic gain control circuits are known that can be used in combination with an electronic amplifier device associated with this lumped parameter circuit to automatically control the amplitude of the increased signal.

These lumped parameter circuits tend to exhibit nonlinear phase-to-frequency propagation characteristics (phase distortion). Phase distortion can cause undesirable ringing, asymmetric preshoots, and overshoots in the processed signal. When a video signal is processed in a television receiver that includes a device that improves high frequency response but has inaccurate nonlinear phase characteristics, the image generated according to the processed video signal is adapted to the viewer. Therefore, if the lumped parameter circuit is not used for the linear phase-to-frequency transfer characteristic, it is generally complicated and expensive, and thus becomes inadequate.

It is known that the desired amplitude and phase characteristics as a frequency function are formed in a device in which a delay signal generated at a signal coupling point (usually referred to as a tap) along a device such as a delay line is combined in a predetermined manner to obtain the desired characteristics. These devices are a. D. US Patent Nos. 2, 263, 376 to Broomrain et al., Hutch. this. Carlman's July 1940 Edition Child. egg. Paper I, R.E, entitled "Short-wave Filter," pp. 28, pp. 302-310. W. Sonnen Hitt's July 1955 edition, the children of television stations and television sets. egg. this. See the article "Interpretation of Choices and Transient Responses" in Volume BTR-1, Volume 3, pages 1 to 8. V. Sperry W. D. Surenian's March 1960 edition of Bell Systems, pp. 39, No. 2, pages 405-422, described in a paper entitled "Temperature equalizers for television circuits."

Such devices, sometimes called transverse equalizers or filters, are commonly used in a variety of signal processing applications. For example, these devices are rain. M. Oliver, U. S. Patent Nos. 2, 759, 044 and Etch. Brimer and S. L. It can be seen that it can be used for horizontal and vertical aperture beam correction as described in US Pat. No. 3,732,360 to Tan. Also, mr. W. Harrison's U. S. Patent No. 2, 922, 965 describes another device of the type described in the Oliver patent coupled to a delay line with multiple tabs so that the reflective end reduces the number of taps required.

tea. As another application of the delay lines described in US Pat. No. 3, 749, 824 to Sagashima et al., The reflector is selectively coupled to the lower end of the light channel delay line during color transmission to suppress the chroma signal. The delay line also serves to compensate for the time delay of the processed signal in the brightness and chroma channels.

Jay in 1970. blood. Bingham wrote his doctoral dissertation to the Graduate School of Maryland, in a dissertation entitled "Linear Distortion of NTSC Color Television Signals," and in 1967. A paper on "Auto equalizer using transverse wave filter" published by Rudin Jr. describes a transverse equalizer for automatically adjusting a degraded video signal according to a control signal derived by comparing the video signal to a reference signal.

In U.S. Patent No. 486,241, entitled "TV Processing Apparatus" filed July 5, 1974 by the inventor of the present invention, the device increases the high frequency component amplitude of the brightness signal and simultaneously attenuates the chromaticity and audio signals. It is described to improve the transient response of video signal processing apparatus. Here, an undesirable viewing pattern is generated if the chromaticity and audio signals do not have their attenuation. The device includes a delay line responsive to a television video signal equipped with a plurality of taps to generate a plurality of delayed video signals. Delayed video signals are synthesized such that the brightness channel has the desired amplitude versus frequency transfer characteristics.

The apparatus described in the aforementioned patent application is provided for preshoot and overshoot that can be easily controlled. In addition, this apparatus has a device for adjusting the peak amplitude of the amplitude versus frequency characteristic of an output signal that does not affect the amplitude of the frequency component or the amplitude of the DC component at five frequencies such as a color subcarrier or an audio intermediate carrier. The device is also arranged such that a portion of the delay line can be used to equalize the time delay derivative of the processed signal in the brightness and chroma channels.

The present invention is useful in an apparatus for automatically controlling signal amplitude in a specific frequency range in accordance with a control signal. Embodiments of the present invention include an automatic color control device and an automatic brightness channel peaking control device.

According to an embodiment of the present invention, a plurality of signal combiners are coupled to a signal delay device responsive to a video signal to represent a plurality of delayed video signals. The first combined signal is generated by combining the first and second delayed video signals having a time interval of at least equal to NT / 2. Where T is the predetermined signal component period of the video signal and N is an integer greater than one. The bandwidth decision signal is derived from at least a third delay video signal. The second combined signal is generated by combining the first combined signal and the bandwidth determination signal. The amplitude of the second combined signal is controlled in response to the control signal derived from the predetermined portion of the video signal. The output signal is derived from at least the second combined signal whose amplitude is controlled.

According to still another aspect of the present invention, the control signal exhibits an amplitude reduction of the high frequency component of the video signal.

Hereinafter, these forms of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, a radio frequency received at an antenna is generated by an intermediate frequency circuit (not shown) and a detection circuit (not shown) to generate a composite video signal including chromaticity, brightness, voice and synchronization signal components. A signal processing apparatus 112 is shown that responds to an (RF) television signal. According to the American standard, the brightness signal has a wide bandwidth (e.g. about 4 MHz) with a low frequency region up to DC (zero frequency) and a high frequency region. The high frequency region (eg, about 2 to 5 MHz) includes chromatic and audio signals. The chroma signal is arranged in a modulated color subcarrier signal at a frequency related to the frequency of the color subcarrier signal (e.g., 3.58 MHz). The speech signal is in the form of a modulated speech subcarrier signal and is arranged at a frequency related to the frequency of the speech subcarrier signal (eg, 4.5 MHz). The fast transition and fine information of the image are included in the high frequency signal component of the brightness signal.

The output of the signal processing device 112 is coupled to the chroma channel 114 and the brightness channel 116. Chromaticity channel 114, which serves to extract the signal from the synthesized video signal within the frequency range of the chromaticity signal (e.g., about 2.1 MHz to 4.2 MHz), includes a bandpass filter 118. The output signal of bandpass filter 118 is amplified by amplifier 120 and coupled to cohabitation detector 122. The output signal of the amplifier 120 is coupled to the burst detector 124 together with the burst gate signal generated by the deflection circuit 142. The burst gate signal includes the pulse synchronized with respect to the sync pulse generated by the sync separator 140 and indicates the time position of the color burst signal included in the synthesized video signal. The burst detector 124 serves to extract the color burst signal from the output signal of the amplifier 120. The color burst signal represents color phase reference information necessary for demodulating the chroma signal. The color burst signal is coupled to a local oscillator 126 having the same frequency as the color subcarrier signal (e.g., 3.58 MHz) and operative to generate a signal that is phase locked to the burst signal phase. Various known devices may be used as the local oscillator 126. The output signal of the local oscillator 126 is coupled to a synchronous detector 122 that provides a color phase reference signal such as, for example, I (in-phase) and Q (right-phase) reference signals. For example, the synchronous detector 122 induces a color difference signal representing R-Y, B-Y, and G-Y information and demodulates the chromaticity signal.

The signal processing device 136 is contained in the brightness channel 116 and attenuates undesirable signals that appear in the brightness channel 116, such as chroma and voice signals, while the high frequency components of the brightness signal to improve the transient response and detail resolution of the television receiver. Emphasize or peak the amplitude. The color burst signals detected by the burst detector 124 are combined and coupled to the amplitude comparator 162 in the signal processing apparatus 136. The color burst signal extracted by the burst detector 124 is also coupled to the amplitude comparator 162 in the signal processor 136. The signal amplitude in the peak amplitude portion of the amplitude versus frequency transfer characteristic of brightness channel 116 is controlled in response to the burst signal and inversely related to the amplitude of the color burst signal. In this manner, the high frequency response of the brightness channel 116 is automatically corrected because the amplitude of the color burst signal (high frequency component) indicates that the high frequency component of the synthesized video signal is attenuated due to transmission loss or the like.

A signal derived from another part of the composite television signal, such as a signal indicating the peak-detected amplitude of the signal within the high frequency range of the composite video signal, may vary the amplitude of the signal in the peak amplitude portion of the amplitude versus frequency transfer characteristic of brightness channel 116. Used to control. Signals such as the vertical band test signal (VITS) for calibrating the television signal processing device can be used for this purpose. Vertical section test signal and similar ones. M. Morris and Jay. Seraphine is the child of the December 1957 edition of the television station and television receiver. this. this. this. Processing PG BTS-9, pages 65 to 69, is described in a paper entitled "Processing report of vertical section television test signal".

It is desirable to control the signal amplitude in the peak amplitude portion of the amplitude versus frequency transfer characteristic of brightness channel 116 directly in relation to the amount of color information in the composite television signal. In the case where the bandwidth of the brightness channel is extended to the frequency range of the chroma and voice signals, it is desirable to prevent undesirable patterns from occurring due to the interaction of the brightness signal and the chroma and voice signals.

The signal processing apparatus 136 is also used to equalize the time delay of the signal processed in the chroma channel 114 and the luminance channel 116.

The output signal of the signal processor 136 is coupled to the brightness processor 138 which amplifies and processes the brightness signal to generate the output signal Y of the brightness channel 116.

The Y output signal of brightness channel 116 and the R-Y, B-Y and G-Y chrominance output signals of chromaticity channel 114 are coupled to kinescope driver 128 where these signals are matrixed to form red, blue and green signals. The red, blue and green signals drive the kinescope 130.

The contrast adjusting device 132 is coupled to the brightness processing device 138 to adjust the amplitude of the brightness signal to adjust the contrast of the image formed by the kinescope 130. The brightness adjusting device 134 is also coupled to the brightness processing device 138. Suitable contrast and brightness adjustment devices are described in US Pat. No. 3,804, 981 to Jack Abbins.

Another portion of the output signal of the video processing device 112 is coupled to a synchronous separator 140 that separates the vertical and horizontal sync pulses from the video signal. The synchronous pulses are coupled from the synchronous separator 140 to the deflection circuit 142. The deflection circuit 142 is coupled to the kinescope 130 and the high voltage device 144 to adjust the deflection and sweep of the electron beam in the kinescope 130 in a conventional manner. The deflection circuit 142 generates a blanking signal coupled to the brightness processor 138 to inhibit the output of the brightness processor 138 during each of these periods to ensure that the kinescope 130 is shut off during the horizontal and vertical retrace periods. The horizontal deflection circuit 142 also generates a burst gate signal coupled to the burst detector 124.

Channels (not shown) also process audio signals.

The general circuit arrangement shown in FIG. 1 is a collar of the type shown in RC A Color Television Service Data 1970 T19 (CTC-49 Type Receiver) issued by RC Corporation in Indianapolis, Indiana. Suitable for use on television receivers.

The signal processing device 136 includes a plurality of signal coupling devices or tabs 152a, 152b, and 152c coupled to the device 150 at consecutive points, and the signal delay device 150 shown by a delay line. The combination of signal delay device 150 and taps 152a, 152b and 152c is called a branched delay line. Although the signal delay device 150 is shown as a delay line, it may be a suitable device for delaying a video signal such as an arrangement of a charge coupling device (CCD'S) or a charge transfer device. Tabs 152a, 152b, and 152c are shown as being directly connected to delay line 15, but they may be coupled to the delay line in such a way that they have signal coupling such as capacitive coupling.

Taps 152a, 152b, and 152c provide the respective delayed video signals a ₁ , b ₁ and c ₁ with time delays T _D1 , T _D1 + T ₁₁ , T _D1 + T ₁₁ with respect to the input video signal Vi ₁ . Coupled to delay line 150 at intervals to mark + T ₂₁ . Delay line 150 includes a portion 156 having a time delay interval T _D1 prior to tap 152a selected relative to the other portion of delay line 150 to equalize the time delay of the signal processed in brightness channel 116 and chroma channel 114. For this purpose, it is desirable for the sum of T _D1 and T ₁₁ to equal the difference between the time delays of the signals processed in chroma channel 114 and brightness channel 116. It is also believed that a signal resulting from the combination of signals appearing in taps symmetrically disposed around a given point of the delay line has a time delay equal to the time delay average of the synthesized signal. Therefore, if tabs 152a and 152c are placed symmetrically around tab 152b, then the output signal derived by synthesizing the signals shown in tabs 152a, 152b and 152c yields the time required to equalize the time delay of the processed signal in the chromaticity and brightness channels. It will have the same time delay as the delay.

Tabs 152a, 152b and 152c are coupled to amplitude control and signal weighting devices 154a, 154b and 154c, respectively. The amplitude control devices 154a, 154b and 154c act to modify the amplitudes of the delayed video signals a ₁ , b ₁ and c _{1 with} predetermined gain and weight values, respectively, to generate a number of amplitude controlled and weighted signals, respectively. Devices 154a, 154b, and 154c may be formed by suitable gain control circuitry, including, for example, amplifiers or attenuators in which the gain may be set at predetermined values above and below the unit amount.

The amplitude control signal generated by the devices 154a, 154b and 154c is a summation circuit 158 in which the amplitude control signal generated by the amplitude control devices 154a and 154c is extracted from the amplitude control signal generated by the amplitude control device 154b to form a composite signal V _P1 . Is coupled to. The summation circuit 158 is formed of a device that algebraically sums signals such as an operational amplifier, a resistance matrix, and the like.

The amplitude control devices 154a, 154b, and 154c are coupled to the respective tabs 152a, 152b, and 152c to represent the general functional devices of the signal processing device 136, but are not particularly equipped for all cases. Thus, for example, if a predetermined gain value such as 1 is desired, a particular amplitude control device can only be directly connected between each tap and summing circuit 158. Furthermore, devices 154a, 154b, and 154c may be included in summing circuit 158.

The synthesized signal generated by the summation circuit 158 is called V _P1 , where “P” is peaking. As will be seen later, V _P1 determines the peaking characteristic of the signal processor 136. The amplitude control signal generated by the device 154b is referred to as V _bw1 , where “bW” refers to the bandwidth, and when combined with V _b1 , V _bw1 determines the bandwidth characteristics of the signal processing device 136.

Signal V _P1 is coupled to peaking control circuit 160 which modifies the amplitude of V _P1 to generate signal PV _P1 . Where P represents the gain of the peaking control circuit 160. The peaking control circuit 160 may be formed of a suitable gain controllable device according to a control signal such as an automatic gain control (AGC) amplifier and arranged so that their range is from a value smaller than a unit amount to a value larger than a unit amount. . The gain P of the peaking control circuit 160 is controlled according to the control signal generated by the amplitude comparator 162.

The amplitude comparator 162 serves to generate, for example, a direct current control signal in response to the color burst signal and the direct current reference voltage from the burst detector 124 and to indicate the difference between the amplitude and the reference voltage of the burst signal. The amplitude comparator 162 may include, for example, a peak detector for detecting the amplitude of the burst signal and a differential amplifier having an input coupled to a reference voltage and an output signal of the peak detector, respectively. Therefore, the amplitude of the signal PV _P1 is controlled in accordance with the deviation of the peak amplitude of the burst signal from the reference signal. Since the amplitude of the burst signal indicates attenuation of the high frequency components of the video signal, it is preferable to arrange the peaking control circuit 160 so that the gain is controlled inversely with the amplitude of the control signal generated by the amplitude comparator 162.

The signals PV _P1 and V _bw1 are logarithmically summed and combined into a summation circuit 164 which generates the output signal V ₁ of the signal processing device 136.

The operation of the signal processing apparatus 136 will be described by way of example. Here, the pair of taps 152a and 152c are symmetrically positioned around the tap 152b and the time intervals T ₁₁ and T ₂₁ are equal to 1 / f, and f is the frequency of the signal component of the composite video signal Vil which appears unnecessarily on the brightness channel 116. For example, f is the signal frequency in the chromatic and speech subcarrier frequency range. In other words, f may be a color subcarrier frequency (eg, 3.58 MHz) or a voice subcarrier frequency (eg, 4. MHz). Also as an example, the selected gain values of the amplitude control devices 154a, 154b and 154c have values of 1/2, 1 and 1/2 respectively.

The operation of the signal processor 136 of FIG. 1 illustrates the amplitude versus frequency transfer characteristics associated with the signal generated by the signal processor 136 of FIG. This can be seen from Figure 2.

Before explaining FIG. 2, the amplitude versus frequency transfer characteristics of a tap delay line or similar device will be briefly described. The amplitude versus frequency propagation characteristics of a portion of the delay line that gives a time delay T to the applied signal can be expressed as a coefficient that changes as a natural function of the frequency e- ^jwT . Because e ⁰ = 1, the amplitude-to-frequency transfer characteristics associated with the signal appearing at the tap at the reference point T = 0 are due to the def5nition flat. The amplitude-to-frequency propagation characteristics associated with the signal resulting from the algebraic addition of two signals generated at each tap symmetrically disposed around the reference point are changed into a cosine function.

Referring now to FIG. 2, the amplitude versus frequency transfer characteristics associated with the V _bW1 , V _P1 , PV _P1 and V ₁ signals generated by the signal processing device 136 of FIG. 1 are shown. These amplitude band frequency transfer characteristics are classified into V _bW1 , V _P1 , PV _P1 and V ₁ . Also shown in FIG. 2 is an amplitude versus frequency characteristic of 1/2 (a ₁ + c ₁ ), which results from the logarithm of the amplitude control signal generated by the amplitude control devices 154a and 154c in FIG. Is associated with the signal. According to the value of the above embodiment, the signals V _bW1 , V _P1 , PV _P1 and V ₁ are derived from the video signals a ₁ , b ₁ and c ₁ delayed by the signal processing apparatus 136 according to the following equation.

V _bW1 = b ₁ (1)

V _P1 = V _bW1 ^-1 / ₂ (a ₁ + c ₁ ) (2)

PV _P1 = P (V _bW1 ^-1 / ₂ (a ₁ + c ₁ )) (3)

V ₁ = PV _P1 + V _bW1 (4)

The amplitude versus frequency transfer characteristic of FIG. 2 can be understood by considering the position of tap 152b as a reference point. According to this concept, it can be seen that the amplitude vs. frequency transfer characteristic of V _bW1 is due to the positive plane. Since the amplitude-to-frequency transfer characteristics of a signal derived by algebraically adding signals appearing in a pair of symmetrically arranged taps are a cosine function, the amplitude-to-frequency transfer characteristics associated with 1/2 (a ₁ + c ₁ ) It is a sine function and has a circulation speed f, which is the minimum amplitude at f ₁₂ and the maximum amplitude at f. Since V _P1 is generated by algebraically subtracting 1/2 (a ₁ + c ₁ ) from V _bW1 , the amplitude-to-frequency transfer characteristics associated with V _P1 and PV _P1 have a cyclic velocity f as a cosine function, f / 2 The maximum amplitude at and the minimum amplitude at f.

Since V ₁ is generated by algebraically adding PV _P1 and V _bW1 , the amplitude-to-frequency transfer characteristic associated with V ₁ is a cosine function and has a cyclic velocity f, the maximum amplitude at f / 2, and the minimum amplitude at f. They are superimposed on the level determined by the predetermined gain value of the amplitude control device 154b.

The peaking characteristic of the signal processing apparatus 136 of FIG. 1 is determined by a signal derived by algebraically adding delayed video signals a ₁ and c ₁ . On the other hand, the bandwidth characteristic of the signal processing apparatus 136 is determined by the signal derived from the video signal b ₁ delayed in combination with the signal V _P1 . It is desirable to space the delayed video signals a ₁ and c ₁ that are properly separated at time intervals such as NT / 2. Where N is an integer and T is the inverse of the frequency f. Preferred ranges of N include integers 2 and 5, although other values of N may be used in certain examples.

The peak amplitude of the amplitude versus frequency transfer characteristic of the signal processing apparatus 136 is automatically controlled by controlling the amplitude of V _P1 in response to a control signal derived from the selected portion of the video signal as described above with reference to FIG. . The peak amplitude of the amplitude versus frequency transfer characteristic associated with V ₁ is controlled according to the control signal, but there is no amplitude at direct current (ie zero frequency). This is because the amplitude contribution that the amplitude-to-frequency transfer characteristic associated with PV _P1 contributes to the amplitude-to-frequency transfer characteristic associated with V ₁ is zero at dc. This is preferable because the screen luminance determined by the direct current component of the brightness signal is not affected by the control signal.

The amplitude transition of the output signal V ₁ of the signal processing device 136 of FIG. 1 includes a preshoot before the transition and an overshoot after the transition. Since this preshoot and overshoot strengthen the amplitude transition of V ₁ , for example, the image immediately before the transition becomes stronger white than that in the normal picture, and the image immediately after the transition is stronger than that in the normal picture. Since it becomes black, the image transition from white to black becomes strong.

In addition, phase-to-frequency transfer characteristics are related to preshoot and overshoot. For example, the linear phase-to-frequency propagation characteristics depend on the formation of the same preshoot and overshoot. The preshoot and overshoot are controlled by a signal formed by the sum of the amplitude control signals associated with the taps 152a and 152c. Therefore, although the selected gain values of the amplitude control devices 154a and 154c are selected equally and the time intervals T ₁₁ and T ₂₁ are also selected, due to the linear phase-to-frequency transfer characteristics formed by the same preshoot and overshoot, the taps 154a and The amplitude control signal associated with 154c may be varied to produce an unbalanced preshoot and overshoot to compensate for phase-to-frequency nonlinearity in different parts of the video signal processing system.

In FIG. 2, if it is desired to have a minimum amplitude at a color subcarrier frequency of 3.58 MHz, for example to relatively attenuate the chroma signal part, T ₁₁ and T ₂₁ are chosen to be about 280 ns, which is the inverse of the color subcarrier frequency. Should be. By selecting T ₁₁ and T ₂₁ as much as 280ns, the peak amplitude point of the amplitude versus frequency characteristic of the brightness signal occurs at about 1.78MHz.

In order to maximize the high frequency response of the brightness channel, it is preferable that the peak of the amplitude band frequency characteristic occurs at the high frequency component of the brightness signal which is a frequency component close to the color subcarrier (3.58 MHz). It may be better than the signal processing apparatus 136 of FIG.

The signal processor 336 of FIG. 3 may be used in place of the signal processor 136 of FIG. 1 where it is desirable to provide high frequency peaking consistent with effective trapping. The similarity between the signal processing apparatus of FIGS. 1 and 3 can be easily seen by comparing the first and third diagrams. Because of this similar form of the signal processing apparatus 336 of FIG. 3 and the signal processing apparatus 136 of FIG. 1, the signal processing apparatus 336 of FIG. 3 will not be described in detail.

Four taps 352a, 352b, 352c and 352d are associated with the input video signal Vi ₃ at the respective time intervals T _D3 T _D3 + T ₁₃ T _D3 + T ₁₃ + T ₂₃ and T _D3 + T ₁₃ + T ₂₃ + T ₃₃ . The signal is coupled to the delay line 350 at intervals such that the delayed video signals a ₃ , b ₃ , C ₃ and d ₃ are delayed. Delay line 350 is a portion 356 having a time delay interval T _D3 before tap 352a selected for the rest of delay line 350 to equalize the time delay of the signal processed in brightness channel 116 and chroma channel 114 in FIG. Include.

In order to equalize these time delays, it is desirable to equalize the difference between _D3 T, T ₁₃ and T _23/2 is the total chroma and lightness channel time delay of the signal processed in the channel. Further, as described above, signals generated by the combination of signals appearing on taps symmetrically disposed about a given point of the delay line are arranged symmetrically around the midpoint of the delay line 350 (ie, between tabs 352a and 352d). Effective time delay, such as the average time delay of the synthesized signal with the taps 352a, 352b, 352c, and 352d. The output signal derived by synthesizing the signals shown in taps 352a, 352b, 352c, and 352d will have the same desired time delay as the time delay required to equalize the time delay of the processed signal in the chroma and brightness channels.

The amplitude control signals generated by the amplitude control devices 354b and 354c are coupled to a summation circuit 366 that is added logarithmically to generate a signal V _bw3 used to determine the bandwidth characteristics of the signal processing device 336. The amplitude control signal generated by the amplitude control devices 354a and 354d is coupled to the summation circuit 358 together with V _bw3 . The summation circuit 358 acts to algebraically subtract the amplitude control signals generated by the amplitude control devices 354a and 354d to produce the signal V _P3 . The V _P3 signal determines the peaking characteristic of the signal processor 336.

The amplitude of V _b3 is modified by the peaking control device 360 according to the control signal generated by the amplitude comparator 362 to form PV _P3 . Where P is the controlled gain of the peaking controller 360. The signals PV _P3 and V _bw3 are logarithmically added to form the output signal of the signal processing apparatus 336.

The operation of the signal processing apparatus 336 of FIG. 3 is an embodiment in which the taps 352a, 352b, 352c and 352d are symmetrically disposed around the midpoint of the delay line 350 and the time intervals T ₁₃ , T ₂₃ , and T ₃₃ are all equal to f12. I will explain. Where f is the signal component frequency of the synthetic video signal Vi ₃ , which may be undesirable. For example, f may be a signal frequency within the frequency range of the chroma subcarrier and the voice subcarrier. In particular, the f-bone color subcarrier frequency (ie, 3, 58 MHz) or the voice intermediate carrier frequency (eg, 4.5 MHz) may be used. In an embodiment, the selected gain values of the amplitude control devices 354a, 354b, 354c and 354d have values of 1/2, 1/2, 1/2 and 1/2 respectively.

4 shows the in-frequency frequency transfer characteristics associated with PV _P3 , V _bW3 , V _P3 , PV _P3 and V ₃ signals generated by the signal processing device 336 of FIG. 3. This amplitude band frequency transfer characteristic is represented by V _bW3 , V _P3 , PV _P3 and V ₃ . FIG. 4 also shows an amplitude-to-frequency transfer characteristic indicating 1/2 (a ₃ + d ₃ ) associated with the signal resulting from the algebraic addition of the amplitude control signals generated by the amplitude control devices 354a and 354d in FIG. have.

According to the values of the above-described embodiment, the signals V _bW , V _P3 , PV _P3 and V ₃ are derived from the delay video signals a ₃ , b ₃ , c ₃ and d ₃ by the signal processing apparatus 336 according to the following equation.

^{_{V bW3 = 1/2 (b}} 3 + c 3) (5)

V _P3 = V _bW3 ^-1 / ₂ (a ₃ + d ₃ ) (6)

PV _P3 = P (V _bW3 ^-1 / ₂ (a ₃ + d ₃ ) (7)

V ₃ = V + P _{[bW3 ^{V bW3 -1 / 2 (a 3}} + d 3) ] (8)

The amplitude versus frequency transfer characteristic of FIG. 4 can be understood by considering the position of the midpoint of the delay line 350 between the reference points taps 352a and 352d. The amplitude vs. frequency transfer characteristic associated with V _bW3 is a cosine function with a circulation rate of 4f. The amplitude vs. frequency transfer characteristic associated with 1/2 (a ₃ + c ₃ ) has a circulation rate of 4f / 3 and a minimum amplitude of 2f. / 3 cosine function. Since V _P3 is generated by algebraically subtracting 1/2 (a ₃ + c ₃ ) from V _bw3 , the amplitude-to-frequency transfer characteristics associated with V _P3 and PV _P3 have a maximum amplitude point at about 2f / 3. Since V ₃ is generated by algebraically adding 2 PV _{P 3} V _{bW 3} , the amplitude-to-frequency transfer characteristic associated with V ₃ has a maximum amplitude point at about 2f / 3.

In FIG. 4, the amplitude band frequency transfer characteristic associated with V _O3 has a maximum amplitude point at 2f / 3 high frequencies with respect to the frequency f of the zero amplitude point. Therefore, signal processing apparatus 336 provides high frequency peaking.

The peaking characteristic of the signal processing apparatus 336 of FIG. 3 is determined by a signal derived by algebraically adding delayed video signals a ₃ and d ₃ . On the other hand, the bandwidth characteristic of the signal processing apparatus 336 is determined by a signal derived by algebraically adding the delayed video signals b ₃ and c ₃ in combination with the PV _P3 . Of course, the delayed video signals a ₃ and b ₃ are preferably timed at the same time interval as NT / 2. Where N is an integer and T is the inverse of the frequency f. Preferred ranges of N include integers between 2 and 5, but other values of N may also be used in other special applications. The peak amplitude of the amplitude versus frequency transfer characteristic of the signal processing apparatus 336 is automatically controlled by controlling the amplitude of V _P3 in accordance with a control signal derived from a selected portion of a video signal such as a burst signal as described above in FIG. The peak amplitude of the transmission characteristics associated with V ₃ varies with P, but the amplitude does not change with direct current. This is because the amplitude versus frequency transfer characteristics associated with PV _P3 and the amplitude versus frequency transfer characteristics associated with V ₃ are always zero at direct current (ie zero frequency). This is preferable because the screen luminance determined by the direct current component of the brightness signal is not affected by the change in the control signal.

The amplitude transition of the output signal V ₃ of the signal processing device 336 of FIG. 3 includes both the preshoot and the overshoot, the form of which is controlled by the signal generated due to the logarithm addition of the amplitude control signals associated with 352a and 352d. This preshoot and overshoot strengthen the amplitude transition of V ₃ . In addition, the phase-to-frequency transfer characteristics are related to the preshoot and overshoot of the amplitude transition of the signal. Therefore, the amplitude control signal generated by the amplitude control devices 354a and 354b has been selected to form the same preshoot and overshoot to have the linear phase-to-frequency transfer characteristics, but the amplitude control signal generated by the amplitude control devices 354a and 354d. May be selected to generate an unbalanced preshoot and overshoot to compensate for the nonlinear phase-to-frequency transfer characteristics of the other parts of the television signal processing system.

3 and 4, it is advantageous to select the time intervals T ₁₃ , T ₂₃ and T ₃₃ as 140 ns (i.e. 1/2 of the inverse of the 3.58 MHz color subcarrier frequency), which is the amplitude band associated with V ₃ . This is because the frequency transfer characteristic has a peak amplitude at a high frequency around 3.58 MHz, that is, about 2/3 x 3.58 MHz (ie, 2.4 MHz) while effectively allowing 3.58 MHz tapping. The time intervals T ₁₃ , T _23, and T ₃₃ all selected the same time intervals according to the reciprocal of the frequency f of the signal unnecessarily appearing in the brightness channel, whereas it is preferable to select these time intervals differently. Can be. For example, it is preferable to select T ₂₃ as 110 ns and T ₁₃ and T ₃₃ as 140 ns. In this case, the amplitude versus frequency characteristic associated with V ₃ has a value close to zero at about 4.1 Hz, while having a peak amplitude at 2/3 × 3.58 MHz (ie, 2.4 MHz). Therefore, the signal processing apparatus of FIG. 1 is modified so that the frequency component within the range of the chromaticity and the audio signal of the video signal becomes relatively strong, while the amplitude of the high frequency component of the brightness signal is relatively increased.

Since the chroma signal is attenuated differently for the low frequency signal during transmission, it is preferable to automatically control the amplitude of the chroma signal in accordance with a control signal indicating the amount of attenuation. This process is well known as auto color and chroma control (ACC). In a conventional color television receiver, the ACC compares the burst amplitude to a reference voltage (in an amplitude comparator such as amplitude comparator 162 in FIG. 1) and also amplifies the output signal of the chroma signal bandpass amplifier (such as amplifier 120 in FIG. 1). And by coupling the output signal of the comparator to an automatic gain control (AGC) amplifier arranged to do so.

If a closed loop ACC device is provided to the color television receiver of Fig. 1, since the signal indicating attenuation of the high frequency component of the video signal (e.g., the burst signal) is already modified to achieve the ACC, It is desirable to provide control signals to a device separate from the control portion of chromaticity channel 114. Thus, for example, if a closed loop ACC device is provided, it is desirable to provide a separate burst detector in brightness channel 116 between signal processor 112 and amplitude comparator 162.

Referring to FIG. 5, a general apparatus of a color television receiver similar to the apparatus of FIG. 1, including a signal processing apparatus 570, for automatically controlling the amplitude of these signals to relatively strengthen the signal in the frequency range of the chroma signal and provide an ACC. Is shown.

Similar configurations of the apparatus of FIGS. 1 and 5 can be seen by comparing FIGS. Because of the similar form of the first and fifth device, the device of FIG. 5 will not be described in detail. In the signal processing apparatus 570 of FIG. 5, the composite video signal V _i5 is coupled to the delay line 550. Taps 552a, 552b and 552c represent delayed video signals a ₅ , b ₅ and c ₃ , respectively, delayed with respect to V _i5 by time interval 0 (a ₅ matches V _i5 ), T ₁₅ and T ₂₅ . It is coupled to the delay line 550 at intervals. The amplitudes of a ₅ , b ₆ and c ₃ are modified by the amplitude controllers 554a, 554b and 554c, respectively, and the amplitude control signals generated by the amplitude controllers 554a and 554c are generated by the amplitude controller 554b. And are subtracted algebraically from the sum circuit 558 to form the V _P5 signal.

The amplitude versus frequency transfer characteristics associated with V _P5 are similar to those associated with V _P1 in FIG. 2. The position of the peak amplitude point of this amplitude versus frequency transfer characteristic is determined by adding the amplitude control signals associated with the amplitude control devices 554a and 554d. In order to strengthen the signal at the frequency of the chroma signal, it is preferable to select the time interval T ₁₅ + T ₂₅ to coincide with the product of the inverse of the color subcarrier frequency of 3.58 MHz, for example, to give the peak amplitude point at the color subcarrier frequency. .

Thus, for example, if it is desired to attenuate a chroma signal and attenuate an audio signal that appears undesirably in the chroma channel, then T ₁₅ + T ₂₅ should be chosen approximately equal to twice the inverse of the 3.58 MHz color subcarrier. . This selection provides an amplitude-to-frequency transfer characteristic with a peak amplitude at 3.58 MHz and a minimum amplitude at 4.5 MHz, ie the voice subcarrier.

The amplitude of V _P5 is modified by the gain of the peaking control device 560 to generate an output signal V _o5 similar to PV _{P1 in} FIG. 2. Output signal V _o5 is coupled to burst detector 524 which removes the burst signal from V _o5 . The burst signal is coupled to an amplitude comparator 562 where the amplitude of the burst signal is compared to a reference voltage. The output signal of the amplitude comparator 562, which indicates the amplitude reduction of the signal in the frequency range of the chroma signal, is coupled to the peaking control device 560. The gain of the peaking control device 560 is controlled inversely related to the attenuation of the burst signal.

Therefore, the signal processing apparatus 570 operates to automatically adjust its amplitude in accordance with a control signal indicating attenuation of the chroma signal in order to strengthen the signal in the frequency range of the chroma signal and to enable automatic color control.

6, there is shown a signal processing apparatus 670 for automatically controlling the amplitude in accordance with a control signal intensifying the chroma signal and indicating the attenuation thereof. The signal processing apparatus 670 is superior to the signal processing apparatus 570 of FIG. 5 and performs high frequency peaking according to a small bandwidth, so that, for example, the chroma signal can be more easily separated from the brightness and voice signals.

The composite video signal V _i6 is coupled to delay line 650. Tab 652a, 652b, 652c and 652d is the time interval 0 (a ₆ is the same as _{V i6), T 16, T} 16+ T 26 and T ₁₆₊ T ₂₆ + T ₃₆ are each delayed with respect to the V _i6 by It is coupled to the delay line 650 at intervals to represent the delay video signals a ₆ , b ₆ , c ₆ and d ₆ . The amplitudes of a ₆ , b ₆ , c ₆ and d ₆ are modified by amplitude control devices 654a, 654b, 654c and 654d, respectively. The amplitude control signals generated by the amplitude control devices 654b and _654c are coupled to a summation circuit 666 where _these signals are added to generate a _VbW6 signal similar to _VbW3 in FIG. The amplitude control signal and the signal V _bW6 generated by the amplitude control devices 654a and 654d are algebraic from V _bW6 such that the amplitude control signal generated by the amplitude control devices 654a and 654d generates a signal V _P6 similar to V _P3 in _FIG . It is coupled to a summation circuit 658 which is subtracted by.

The amplitude peak position of the amplitude-to-frequency transfer characteristic associated with V _P6 is generated by algebraically adding the amplitude control signals generated by the amplitude controllers 654a and 654d and is similar in amplitude to 1/2 (a ₃ + d ₃ ) of FIG. It is determined by a signal having a large frequency transmission characteristic. In order to extract the chromaticity signal from the composite video signal, for example, it is preferable that the inverse of the color subcarrier frequency of 3.58 MHz and the time interval T ₁₆ + T ₂₆ + T ₃₆ equal to each other, resulting in a peak amplitude point at the color subcarrier frequency. . The signal V _bW6 , when combined with the amplitude control signal generated by the amplitude control devices 654a and 654d, determines the bandwidth of the amplitude versus frequency transfer characteristic associated with V _P6 . Since V _bW6 is formed by algebraically adding the amplitude control signals generated by the amplitude control devices 654b and _654c , select the time interval T ₂₆ to about 130 ns so that the amplitude-to-frequency transfer characteristics associated with V _P6 are zero at 4.5 MHz, the voice subcarrier. It is desirable to have an amplitude.

The amplitude versus frequency transfer characteristics associated with V _P6 (similar to the amplitude versus frequency transfer characteristics of V _P3 in FIG. 4) are asymmetric around the peak amplitude point 2f / 3. In other words, the position of the peak amplitude point is relatively around the zero amplitude point f. As a result, the high frequency component of the chroma signal is attenuated compared to the low frequency component of the esophageal signal. This is desirable because the chroma signal is attenuated with increasing frequency.

In addition, the amplitude-to-frequency transfer characteristics associated with V _P6 have narrower bandwidths and sharper high frequency upward transitions (amplitude decrease with increasing frequency) than the amplitude-to-frequency transfer characteristics associated with V _P5 . As a result, the chroma signal is easily separated from the luminance and the audio signal by the signal processing device 670 rather than the signal processing device 570 of FIG.

Also, since both side bands such as the I and Q side bands associated with the chroma signal are unbalanced, the asymmetrical form of amplitude versus frequency transfer characteristics associated with the signal processing apparatus 670 is well suited for processing chroma signals.

The amplitude of V _P6 is modified by the gain of the peaking control device 660 in accordance with the control signal generated by the amplitude comparator 662 in the same manner as described for the signal processing device 570 of FIG. 5 to generate the output signal V _o6 . .

Claims (1)

As described above and shown in the figures, a video signal source, a signal delay device coupled to the video signal source, a plurality of signal combiners coupled to the signal delay device to represent a plurality of delayed video signals, a first The first and second delayed video signals at intervals such as NT / 2, where N is an integer greater than or equal to 1 and T is a period of the selected signal component supplied from the video signal source. A device for deriving a bandwidth determining signal from a third delay video signal disposed at a suitable time interval between at least the first and second delay video signals, the second device for making a second composite signal A brightness, chromaticity and color burst signal component comprising a second device for combining the bandwidth determination signal and the first composite signal. A device for processing a television video signal, in particular, a device for inducing a control signal in a predetermined portion of the video signal, and controlling the amplitude of the second composite signal in accordance with the control signal to produce a final signal. And a third device for deriving an output signal from at least the final signal.

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