KR800000317B1 - Automatic luminance channel frequency response control apparatus - Google Patents

Abstract

This apparatus comprises a source of video signals, signal delaying means and a plurality of signal coupling means. A delay line(110) suitable for television video signals is included in the luminance channel(16) of a television video signal processing apparatus. A plurality of tops(112a-m) are coupled to the delay line for developing a plurality of delayed video signals. A bandwidth determining signal is derived from at least a third of the delayed video signals located in time between the first and the second delayed signal.

Description

Automatic Brightness Channel Frequency Response Control Device

1 is a schematic and block diagram partially showing a general apparatus of a color television receiver using an embodiment of the present invention.

FIG. 2 is a partial supplementary schematic diagram of the embodiment of the present invention shown in FIG.

3 and 4 are diagrams showing various amplitude wave frequency transfer characteristics associated with the embodiment of the present invention shown in FIG.

FIG. 5 is a schematic diagram of another embodiment of the present invention useful for the general apparatus of the color television receiver shown in FIG.

6 is a diagram showing various amplitude wave frequency transfer characteristics associated with the embodiment of the present invention shown in FIG.

The present invention relates to an apparatus for improving the transient response and fine resolution of a television video signal processing system, and more particularly to an apparatus for automatically controlling the frequency response of a television video signal processing system.

With the advent of larger kinescopes in television receivers, the problem of improving the transient response of television video signal processing systems has become very important. In terms of picture quality, this improvement depends on the reproduction of fine resolution as well as the improved transition between tones.

The color television synthesized signal contains components of brightness, chromaticity, synchronization, and voice signal. According to the American standard, the brightness signal has a relatively wide bandwidth (e.g., about 4 MHz) along with the low frequency region wave being lowered to DC (zero frequency). The high frequency region of the composite signal (e.g., 2-5 megahertz) also includes chromatic and audio signals. The chroma signal has a modulated color subcarrier form and is adjusted to a frequency related to the frequency of the color subcarrier signal (e.g., 3.58 MHz). The voice signal has a voice intermediate carrier signal shape, has a voice intermediate carrier signal shape, and is adjusted to a frequency related to the frequency of the voice intermediate carrier signal (for example, 4.5 MHz). Fine information and sharp changes of an image are included in relatively high frequency signal components of the brightness signal. In order to process these signals, the color television receiver includes a chroma channel for processing the chroma signal, a brightness channel for processing the brightness signal, and a voice channel for processing the audio signal.

In order to improve the fine resolution and sharpness of the image, it is desirable to improve the high frequency response of the lightness channel by providing a lightness channel having a relatively wide bandwidth or by relatively increasing the amplitude of the high frequency components of the lightness signal or both. Do. Enhancing the amplitude of the relatively high frequency component of the brightness signal is called peaking. Increasing the bandwidth of the brightness channel tends to result in a sharper reproduction of the amplitude change. Peaking of the brightness signal tends to result in "preshoot" immediately before the change and "over shoot" immediately after the change, so that the reproduced image portion just before the change is made whiter than the original picture. And the change from white to black will be intensified since it is blacker than the original screen immediately after the change.

However, the high frequency response of the lightness channel is suitably limited by a bandpass filter or similar device to remove the frequency components corresponding to the chromaticity and sound signals from the lightness channel. The presence of chromaticity and voice signal in the brightness channel tends to generate a visibility pattern in the image that annoys the viewer. Therefore, today's color television receivers are manufactured by trade-off between a light channel wave having a maximum high frequency response to fine resolution and a sharp tone change, and a light channel having a limited high frequency response to prevent the occurrence of undesirable visibility patterns in the image.

When the brightness channel does not have a signal such as a chroma signal and an audio signal, since an undesirable visibility pattern cannot be easily generated, an apparatus for automatically controlling the bandwidth of the brightness channel by the amount of undesirable signal present in the brightness channel Has been proposed. These devices are L. Predondal, US Pat. No. 2, 895, 004, G. Pat. Ralston, U.S. Patent No. 2,910,751, Oh. Patterson, US Patent Nos. 2, 910, 528, D. Ritman, US Patent Nos. 3, 139, 484, K. M. John, U.S. Patent Nos. 3,167,611, and T. Sagashima et al., U.S. Patent No. 3,749,824, and the like.

Care should be taken in selecting devices to improve the high frequency response of video processing systems. This is because this high frequency response must be fixed or adjusted automatically in response to a control signal. For example, a relatively wide bandwidth video processing system produces less sharp images than a narrow bandwidth system because the wide bandwidth system nonlinearly or distorts the phase as a function of frequency. That is, since the wideband system generally has a higher frequency of off-frequency characteristics (signal reduction as a frequency increase) than a narrower bandwidth system, the high frequency video signal component is delayed more than the low frequency video signal component. Phase distortion or nonlinearity is mainly indicated by the presence of undesirable asymmetric preshoots and overshoots and rings in the processed video signal. Asymmetric preshoots and overshoots and rings are particularly undesirable because they cannot be easily controlled and produce unpleasant visibility effects for the viewer. In a similar manner, it is necessary to tune to avoid uncontrolled phase distortion of the peaking device in order to enhance the amplitude of the high frequency components of the brightness. In this case too, the viewer is offended due to uncontrolled preshoot, overshoot and ringing of the image generated by the processed video signal. As a result of this phase distortion, the transient response and fine resolution of a video processing system having facilities for improving the high frequency response of the system are worse than expected.

In a device in which the desired amplitude wave phase characteristic (or both) is formed as a function of frequency, a method intended to achieve the desired characteristic of the delay signal generated at the signal coupling point (usually tap) along a delay line or similar device. It is known to combine with. These devices are a. D. US Patent Nos. 2, 263, 376 to Bromrain and Alumni, and 7 Will, 1940, 1940. egg. Equation described in the minutes of this meeting ”Vol. 28, No. 7, 302 to 310. this. Karlman's thesis titled "The Transversal Filter," July 1955, "The Child of Broadcast and Television Receivers." egg. Al W. Sonnefeld's paper titled “Interpretation of Selectivity and Transient Responses” in the minutes of this meeting, and in the Bell Systems Technical Book No. 39, No. 2, pages 405-422, March 1960. V Sperry and D. Schlenian's thesis is commonly found in "Television Circuit Street Lights."

These devices, sometimes called street lights or filters, are useful for changing applications in signal processing. For example, such a device is rain. M. It can be seen that it is useful for horizontal and vertical hole beam calibration as described in Oliver's US Pat. No. 2, 759, 044.

Furthermore, in the apparatus of US Patent No. 3, 749, 824 described above, the reflective end is a method of suppressing the chromatic signal portion, which is selective to one end of the brightness channel delay line in response to a control signal representing color information in the video signal. Are combined. It is described that the delay line is provided to compensate for the brightness and differential delay time of the processed signal in the channel.

Pending U.S. Patent Application No. 486,241, entitled "TV Signal Processing Device" by Joseph Peter Bingham on May 5, 1974, the amplitude of the high frequency components of the brightness signal portion is relatively increased while Or a device for relatively attenuating both amplitudes is described. The apparatus includes a delay line responsive to a television video signal provided with a plurality of taps to generate a plurality of delayed video signals. The delayed video signal is combined to generate the specific response characteristic required for the brightness channel.

The device provides an improved transient response in line with the attenuation of the undesirable signal which mainly produces an undesirable visibility pattern. The device also allows easy control of the preshoot and overshoot.

Moreover, the device controls the peak amplitude of the amplitude versus frequency characteristics of the output signal. This substantially does not affect the amplitude of the DC frequency component around the frequency f, such as chroma or voice subcarrier frequency. Moreover, the device is adjusted so that the portion of the delay line can be used to equalize the differential time delay of the processed signal in the chromaticity and lightness channels.

The present invention is useful for an apparatus for automatically controlling a frequency switch of a predetermined amplitude point of amplitude versus frequency transfer characteristics of a television video signal processing system.

By the present invention, the plurality of signal coupling devices are coupled to a signal coupling device responsive to the video signal. A plurality of delayed video signals are developed in the signal combiner. The first combined signal is generated by combining the NT / 2 first and second delayed video signals that are separated in time by substantially the same time interval, where T is the duration of the predetermined signal component of the video signal, and N Is an integer greater than 1 wave. The first bandwidth determination signal is derived from at least a third delay video signal. The second bandwidth determination signal is derived from fourth and fifth delayed video signals that are located in time between the first and second delayed video signals. The second combined signal is generated by combining the first combined signal with one bandwidth determination signal. The third bandwidth determination signal is derived by selectively combining the controllable amplitude portions of the first and second bandwidth determination signals. The second combined signal is combined with the third bandwidth determination signal to generate an output signal. The bandwidth of the output signal is determined by the third bandwidth determination signal, while the peaking characteristic of the output signal is determined by the first combined signal.

According to another aspect of the present invention, the controllable amplitude portions of the first and second bandwidth determination signals are controlled in inverse relationship with each other in response to the control signal.

According to another aspect of the present invention, the control signal indicates the amount of color information present in the video signal. In this respect, the controllable amplitude portion of the first bandwidth determination signal is controlled in inverse proportion to the amplitude of the color information, and the controllable amplitude portion of the second bandwidth determination signal is directly proportional to the amplitude of the color information.

According to yet another aspect of the present invention, the first combined signal comprises a sixth and seventh timely located between the controllable amplitude portion summating the first and second delayed video signals and the first and second delayed video signals. It is generated by combining the controllable amplitude portion of the sum of the delay video signals. In this respect, the controllable amplitude portion of each sum signal is automatically controlled by the control signal.

Referring to FIG. 1, received by an antenna to generate a composite video signal containing chromaticity, brightness, voice and synchronization signals by means of devices of suitable intermediate frequency circuits (not shown) and detection circuits (not shown). A signal processing unit 12 is shown that responds to a radio frequency (RF) television signal. The output of the signal processing unit 12 is applied to the chroma channel 14 and the brightness channel 16.

Chromaticity channel 14 includes a bandpass filter 18 provided for extracting signals in the frequency domain of the chromaticity signal (e.g., approximately 2.1 to 4.2 megahertz) from the composite video signal. The output signal of the bandpass filter 18 is amplified by the amplifier 20 and applied to the synchronous detector 22. The output signal of the amplifier 20 is also applied to the burst detector 24 together with the burst gate signal generated by the deflection circuit 50. The burst gate signal constitutes synchronized pulses with respect to the sync pulse generated by the sync separator 48 and represents the time position of the color burst signal included in the composite video signal. Burst detector 24 is provided to extract the color burst signal from the output signal of amplifier 20. The color burst signal represents color phase reference information required for demodulating the chroma signal. The color burst signal is coupled to a lock oscillator 26, which is provided to generate a signal having the same frequency as the color subcarrier signal (e.g., 3.58 MHz) and phase locked to the phase of the burst signal. . Various known designs for locking the oscillator 26 are used. The output signal of the lock oscillator 26 is applied to a synchronous detector 22 which is used to provide a color phase reference signal, for example I (phase) and Q (spherical) signals. A synchronous detector is provided to demodulate the 22 chroma signal and ultimately to derive the color signal representing eg the R-Y, B-Y and G-Y information.

The color killer circuit 28 is coupled to the output of the burst detector 24 and generates a signal to prevent operation of the sync detector 22 (or other portion of chromaticity channel 14) when the amplitude of the burst signal is below a predetermined threshold level. Is provided.

Amplitude detector 30 is coupled to the output of amplifier 20 and provided to generate a chromaticity passband amplitude signal representing the amplitude of the signal in the chromatic frequency domain. The chromaticity passband amplitude signal indicates the amount of color information in the video signal and is applied to the signal processing unit 36 through the conductive line 32 to control its operation. In a similar manner, the output of the color killer circuit 28 is also applied to the signal processing circuit 36 as indicated by the dashed line 34.

Signal processing unit 36 is included in brightness channel 16 and provided to attenuate undesired signals present in brightness channel 16, such as chroma or audio signals or both, while improving brightness and transient response of television receivers. Peak or relatively intensify the high-frequency component amplitudes of the signal. The signal processing unit 36 includes facilities for automatically controlling the bandwidth of the brightness channel 16 in response to the control signal generated in the chromaticity channel 14. The signal processing unit 36 also has provisions for controlling the amplitude of the peak portion of the brightness channel frequency response in response to a control signal generated in the chromaticity channel 14 or also a manual control signal. Furthermore, the signal processing unit 36 is provided to uniformize the time delay of the signal processed in the chroma channel 4 and the luminance channel 16.

The output signal of the signal processing unit 36 is applied to the brightness processing unit 38 which amplifies and processes the brightness signal to generate the output signal Y of the brightness channel 16.

The Y output signal of brightness channel 16 and the R-Y, G-Y and B-Y color differential output signals of chromaticity channel 14 are applied to kinescope driver 40, where the output signals are matrixed to form R, G and B color signals. These R, G and color signals drive kinescope 42.

The contrast control unit 44 is coupled to the brightness processing unit 38 to control the amplitude of the brightness signal and thus control the contrast of the image generated by the kinescope 42. The brightness control unit 46 is also coupled to the brightness processing unit 38. Suitable contrast and luminance control devices are described in US Pat. No. 3,804, 981 to Jack Evans.

The other output signal portion of video processing unit 12 is applied to synchronous separator 48 which separates the horizontal and vertical sync pulses from the video signal. The sync pulse is applied to the deflection circuit 50 from the sync separator 48. The deflection circuit 50 is coupled to the kinescope 42 and the high pressure unit 52 to control the dissipation or deflection of the electron beam in the kinescope 42 in a conventional manner. The deflection circuit 50 also generates an erase signal applied to the brightness processing unit 38 to interrupt the output of the brightness processing unit 38 during the horizontal and vertical retrace periods, and ensures the shut-off of the kinescope 42.

Also provided are channels (not shown) for processing voice signals.

The general circuit arrangement shown in FIG. 1 is, for example, a color television receiver of the type R C. Color Television Service Data 1970, No. T 19 (CTC-49 type receiver), published by R. C. Corporation of Indianapolis, Indiana. Suitable for use on

The signal processing unit 36 includes a signal delay device 110 shown by a delay line and a plurality of signal coupling devices or tabs 112a, 112b, 112m, 112c and 112d coupled to the signal delay device 110 at continuous points. The combination of signal delay device 110 and tabs 112a, 112b, 112m, 112c and 112d is sometimes referred to as tab forming delay lines. The delay device 110 is shown in inductive or coiled form of a delay line, but it may be any other suitable device for delaying video signals, such as arrangement of charge coupled devices (CCDs) or charge transfer devices. Although maps 112a, 112b, 112m, 112c and 112d are shown as being connected in series to a delay line, they may be coupled to the delay line in other suitable ways to provide capacitive coupling or similar signal coupling.

Taps 112a, 112b, 112m, 112c and 112d respectively represent time intervals T _D , T _D + T ₁ , T _D + T ₁ + T ₂ , T _D + T ₁ + T ₂ + T ₃ and T _D + T ₁ The delay lines 110 are spaced apart at intervals so as to develop angular delay video signals a, b, m, c and d which are delayed at a first time related to the input video signal by + T ₂ + T ₃ + T ₄ . Delay line 110 includes a portion 116 having a time delay interval T _D before tap 112a is selected with respect to another portion of delay line 110 to equalize the time delay of the signal processed in brightness channel 16 and chroma channel 14. do. In order to equalize the time delay of the signal processed in the chromaticity and lightness channels, it is preferable that the sum of T _D , T ₁ and T ₂ equals the difference between the time delays of the signals processed in chromaticity channel 14 and lightness channel 16. In addition, it should be noted that a signal resulting from the combination of signals developed at taps symmetrically arranged around a given point of the delay line has a time delay equal to the average of the time delays of the combined signals. Therefore, when tabs 112a, 112b, 112c and 112d are symmetrically disposed around tab 112m, the output signal derived by combining the signals developed in tabs 112a, 112b, 112m, 112c and 112d is processed in the chromaticity and brightness channels. It will have the same time delay as the time delay required to equalize the time delay of the signal.

Tabs 112a, 112b, 112m, 112c and 112d are coupled to amplitude control or signal weighting devices 114a, 114b, 114m, 114c and 114d, respectively. The amplitude control device 114 is provided to modify the amplitudes of the delayed video signals a, b, m, c and d by each predetermined gain or weight to generate a plurality of amplitude control or weighted signals. The amplitude control devices 114a, 114b, 114m, 114c and 114d are formed by any suitable gain control circuit including, for example, an amplifier or an attenuator, where the gain is fixed to a predetermined value of one and up.

The amplitude control signals generated by the amplitude control devices 114b and 114c are applied to the addition circuit 118, where they add logarithmically to generate the output signal _Vbw2 . As can be seen, the signal V _bw2 is useful for determining the bandwidth of the output signal V ₀ of the signal processing unit 36. Thus, the symbol "bw" is used to indicate bandwidth. The addition circuit 118 is formed by any circuit suitable for algebraically adding signals such as operational amplifiers and resistive matrices. The amplitude control signal generated for the amplitude control devices 114a and 114d is applied to the addition circuit 120 together with V _bw2 . The addition circuit 120 is similar to the addition circuit 118, and is provided to logarithmically subtract the amplification control signals generated by the amplification control devices 114a and 114d so that the signal V _P is generated at V _bw2 . As can be seen, the signal V _P is useful for determining the peaking characteristic of the output signal of the signal processing unit 36. Here the symbol p stands for peaking.

Although the amplitude control devices 114a, 114b, 114n, 114c and 114d are coupled to the respective tabs 112a, 112b, 112m, 112c and 112d to show the general functional devices of the signal processing unit 36, they are not particularly provided in all cases. For example, if the same predetermined gain value is required for 1, the specific amplitude control device is only connected in series between each tap and the addition circuit. Furthermore, the amplitude control devices 114a, 114b, 114m, 114c and 114d may be included in the addition circuits 118 and 120. The amplitude control signal generated by the amplitude control means 114m and the output signal of the addition circuit 118 are applied to the mixer unit 122. As can be seen, the amplitude control signal generated by the amplitude control device 114m is also useful for determining the bandwidth of the output signal of the signal processing unit 36 and is therefore _denoted V _bw1 . From channel 14. The control signal is also applied to mixer unit 122 via leads 32 or 34. Mixer unit 122 generates an output signal V _bw3 that includes a combination of controlled amplitude portions of V _bw1 and V _bw2 controlled by the control signal from chromaticity channel 14. That is, V _bw3 is equal to the sum of the amplitude control section of the amplitude V _bw1 portion and _bw2 V control, V the amplitude control portion of _bw1 and _bw2 V is in inverse relation to each other control. As can be seen, the controlled amplitude portion of V _bw2 is controlled inversely with the amount of color information, and the controlled amplitude portion of V _bw2 is adapted to automatically control the bandwidth in brightness channel 16 by the amount of color information present in the composite video signal. Controlled in proportion to the amount of color information.

In FIG. 2, which is a schematic diagram of a mixer unit 122 circuit, the three transistor differential amplifier stages 212, 214, and 216 are adjusted in a multiplier or triple form to generate an output signal of the form A _V1 + (1A) V ₂ , Where V ₁ and V ₂ are the two input signals, and A is the overall gain of the circuit.

Relatively constant current I is generated by constant current source 218.

Several known temperature compensation and power compensation current sources are used. Current I is divided into two branches of differential stage 212 to form currents A'I and (I-A ') I. Where A 'is the single stage gain of differential stage 212. The single stage gain A 'of the differential stage 212 is controlled by the amplitude of the control signal applied to the differential stage 212.

Currents A'I and (I-A ') are applied to differential stages 214 and 216, respectively, to determine their respective gains. The non-inverting or positive single-ended output signal of the differential stage 214 is added to the inverting or negative single-ended output signal of the differential board 216 to form an output signal.

The chromaticity passband amplitude signal from the chromaticity channel 14 of FIG. 1 and V _bw1 , V _bw2 are connected to the appropriate terminals of the FIG. 2 circuit so that a signal of the form AV _bw1 + (1-A) V _bw2 is generated, It will be _{appreciated that} the controlled amplitude portions of V _bw1 and V _bw2 are in response to chromaticity passband amplitude signals and are controlled inversely to each other.

The circuit of FIG. 2 is adjusted to selectively switch the output signal between V _bw1 and V _bw2 under the influence of a color killer signal or similar signal as indicated by dashed line 34 in FIG.

Referring to FIG. 1, the output signal V _P of the addition circuit 120 is applied to the peaking control circuit 124 used to modify the amplitude of V _P to generate the signal P _VP , where _P is the peak of the peaking control circuit 124. Gain (or decay rate).

The peaking control circuit 124 is formed by an appropriately adjustable gain device, such as a variable gain amplifier, and is adjusted to form a gain area that extends from a value less than one to a value greater than one. The gain P of the peaking control circuit 124 is manually adjusted or controlled in response to a control signal such as the chromaticity passband amplitude signal by the conductive line 126 indicated by the dotted line. It is preferable that the signal processing unit 36 adjusts its amplitude band frequency transmission characteristic to have a peak at a relatively high frequency near the frequency region of the chroma signal. It is desirable to control the peak amplitude of the amplitude-to-frequency response specific peak in inverse relation to the amount of color information of the video signal.

The output signal P _VP and the signal V _bw3 of the _peaking control circuit 124 are applied to the addition circuit 128. _Adder circuit 128 is similar to adder circuits 118 and 120 and is provided to add P _VP and V _bw3 algebraically to generate output signal V ₀ of signal processing unit 36. It should be noted that peak control circuit 124 may not be required unless adjustment of the peak amplitude of V _P applied directly to adder circuit 128 and amplitude versus frequency response characteristics of signal processing unit 36 is required.

The operation of the signal processing unit 36 of FIG. 1 will be well understood with reference to FIGS. 3 and 4, and FIGS. 3 and 4 are amplitude versus frequency transfer characteristic diagrams associated with the signal destination unit 36. FIG.

Before describing FIGS. 3 and 4, the amplitude versus frequency transfer characteristics of a tap delay line or similar device will be briefly reviewed. The amplitude versus frequency propagation characteristic of a portion of the delay line that provides the time delay T to the applied signal is expressed as a frequency function, that is, an exponentially varying coefficient such as natural logarithm e ^jwt . Therefore, the amplitude-to-frequency propagation characteristics associated with the signal generated by algebraically adding two signals generated at each tap positioned symmetrically with respect to the reference point change as a cosine function.

For example, in the operation of the signal processing unit 36 of FIG. 1 to be described, the pair of tabs 112a, 112d, 112b, 112c are symmetrically positioned around the tab 112m, and the time intervals T ₁ , T ₂ + T ₃ and T ₄ are all the same and 1 / 2f where f is is is present in the frequency and this is undesirable first-degree brightness channel 16 of the signal component of the composite video signal V _i. For example, f is the signal frequency in the frequency domain of chromaticity or speech subcarriers or both. In particular, f may be a color subcarrier frequency (e.g., 3.58 MHz) or a voice intermediate carrier frequency (e.g., 4.5 megahertz).

By way of example, the predetermined gains of the amplitude control devices 114a, 114b, 114m, 114c and 114d typically have values of 1/2, 1/2, 1, 1/2 and 1/2 respectively.

3 shows the amplitude versus frequency transfer characteristics associated with the generated output signal V ₀ and the signals V _bw1 , V _bw2 , V _P and P _VP generated in the signal processing unit 36. These amplitude band frequency transfer characteristics are classified into V _bw1 , V _bw2 , V _P and P _VP for convenience. With the exemplary values given above, the signals V _bw1 , V _bw2 , V _P and P _VP are derived from the video signals a, b, m, c and d delayed by the signal processing unit 36 according to the following equation.

V _bw1 = m (1)

V _bw2 = 1/2 (b + C) (2)

V _P = 1/2 (b + c) -1/2 (a + d) (3)

P _VP = P [1/2 (b + c) -1/2 (a + d)] (4)

Also shown is an amplitude versus frequency characteristic classified as [1/2 (a + d)] related to the sum of the amplitude control signals generated by the amplitude control devices 114a and 114d in FIG.

In FIG. 3, it can be seen that the amplitude versus frequency characteristic associated with V _bw1 is shown in a straight line. In addition, the amplitude vs. frequency transfer characteristic related to V _bw2 is the cosine function having a cycle rate of 4f, and the amplitude vs. frequency transfer characteristic related to 1/2 (a + d) is the cosine function having a cycle rate of 4 / 3f. have.

By considering FIG. 3, the amplitude versus frequency transfer characteristics associated with V _bw1 (derived from the delayed video signal m) are relatively higher than the amplitude versus frequency transfer characteristics associated with V _bw2 (derived from the sum of the delayed video signals b and c). It can be seen that it has a larger bandwidth. As can be seen, the amplitude versus frequency transfer characteristics associated with the V _bw3 has a bandwidth that varies in bandwidth between related V _bw1 and V _bw2 in response to a control signal generated in the chroma channel 14 (shown in FIG. 4). The amplitude versus frequency transfer characteristic associated with V _bw3 determines the bandwidth of brightness channel 16 when combined with the amplitude versus frequency transfer characteristic associated with P _VP .

Considering Figure 3, it can be seen that the propagation characteristic associated with 1/2 (ad) has a negative maximum amplitude point at 2 / 3f. Equations (2) and (3) show that V _P is formed by subtracting 1/2 (a + d) from V _bw2 and the transmission characteristic associated with V _P has a peak amplitude at approximately 2 / 3f. Thus, the amplitude versus frequency transfer characteristic associated with the sum of delay signals a and d is useful for determining the peaking characteristic of brightness channel 16. It is preferable to isolate by time intervals such as NT / 2 to separate the delayed video signals a and d in time, where N is an integer and T is the inverse of the frequency f. Although the aforementioned range of N is an integer between 2 and 5, other values of N also become useful for certain applications. V _P is _derived from the signal processing unit 36 of FIG. 1 by subtracting the amplitude control signal generated by the amplitude control devices 114a and 114d from V _bw2 , while V _P is generated by the amplitude control devices 114a and 114d from V _bw1 . The amplitude control signal can be derived by subtracting algebraically.

From the consideration of FIG. 3, it can be seen that the adjustment of the gain P of the peaking control circuit 124 of FIG. 1 does not affect the amplitude of the amplitude versus frequency transfer characteristic associated with P _VP at DC (i.e., zero frequency) or frequency f. have.

Referring to the signal processing unit 36 of FIG. 1 by way of example, the mixer 122 is in the form shown in FIG. 2 and generates an output signal as follows.

V _bw3 = AV _bw1 + (1-A) V _bw2

Where A is the controllable gain of the mixer of FIG. 2, and the amplitude versus frequency transfer characteristics of V _bw1 and V _bw2 are shown in FIG. In this embodiment, the general equation for V ₀ is as follows.

V ₀ = AV _bw2 + (1-A) V _bw2 + P _VP (6)

4 Referring to FIG., A = 0 and V ₀ is the general case of V _bw3, AV _bw1, amplitude versus frequency transfer characteristics associated with the (1-A) V _bw2, and V ₀ is also shown when the. In FIG. 4, the amplitude band frequency transfer characteristic associated with P _VP is repeated as FIG. 3 for the purpose of relating the amplitude band frequency transfer characteristics of the third and fourth degrees.

A gain is due to be changed between 1 and 0, the transfer characteristics associated with the V _bw3 will change in correspondence between the amplitude versus frequency transfer characteristic of the V _bw1 and _bw2 V.

As can be seen from equations (5) and (6), V ₀ is the sum of V _bw3 and P _VP . Therefore, the amplitude versus frequency transfer characteristic associated with V ₀ is controlled by the value of gain A. The amplitude-to-frequency transfer characteristic corresponding to the minimum bandwidth of brightness channel 16 represents when the value of A is zero (as shown in FIG. 4). Since V ₀ is equal to P _VP added to the linear transfer specification of V _bw1 with amplitude 1 (not shown in Figure 4), the amplitude-to-frequency transfer specificity of V ₀ corresponding to the maximum bandwidth of brightness channel 16 is A. The value of represents 1 day.

From FIG. 4, the peak amplitude value of the V ₀ related amplitudemer frequency transfer characteristic varies directly with the value of A.

Note that although the peak amplitude of the amplitude versus frequency transfer characteristic associated with V _O changes with A, it is not DC amplitude. This is because the amplitude of the sum of AV _bw1 and (1-A) V _bw2 at DC is always 1. Furthermore, it should also be noted that although the peak amplitude of the transmission characteristics associated with V ₀ changes with P, it is not the amplitude of DC. This is because the amplitude of the amplitude versus frequency transfer characteristic relative to P _VP relative to V ₀ is always zero at DC. It is desirable not to affect the amplitude of the amplitude versus frequency transfer characteristic. This is because the screen luminance is determined by the DC component of the brightness signal.

Therefore, the bandwidth of the signal processing unit 36 is controlled by controlling the formation of V _bw3 . In particular, when the control signal representing the amount of color information present in the video signal indicates a relatively large amount of color information, V _bw3 mainly constitutes a combination of two delay signals b and c having an amplitude-to-frequency transfer characteristic with a relatively large bandwidth.

When the signal representing the amount of color information present in the video signal indicates a relatively small amount of color information, V _bw3 mainly constitutes a delayed video signal m having an amplitude-to-frequency transfer specificity having a relatively large bandwidth.

Referring to Figures 3 and 4, the time intervals T ₁ , T ₂ + T ₃ and T ₄ are advantageous as 140 nanoseconds (i.e. reciprocal of the color carrier frequency of 3.58 MHz). When brightness channel 16 is the minimum bandwidth condition (i.e., A = 1), the amplitude-to-frequency transfer characteristics associated with V ₀ are approximately 2/3 x 3.58 at relatively high frequencies around 3.58 MHz. It has a peak amplitude of megahertz (i.e. 24 MHz) while providing an effective 3.58 MHz cutoff.

Although the time intervals T ₁ , T ₂ + T ₃ and T ₄ are equally chosen for the examples, these time intervals are preferably chosen differently. For example, it is preferable to set T ₂ + T ₃ to 110 nanoseconds and T ₁ and T ₄ to 140 nanoseconds. In this case, the amplitude versus frequency characteristic associated with V ₀ will have a value of substantially zero at approximately 4.1 MHz, while having a peak amplitude at approximately 2/3 × 3.58 MHz (ie, 2.4 MHz). Accordingly, the signal processing apparatus of FIG. 1 can be modified so that the frequency components of the video signal and the frequency components in the region of the audio signal are relatively attenuated, while the relatively high frequency components of the brightness signal are relatively increased in amplitude.

The amplitude variation of the output signal V ₀ of the signal processing unit 36 of FIG. 1 includes both the preshoot and the overshoot.

This preshoot and overshoot are provided to intensify the amplitude variation of V ₀ . Moreover, phase-to-frequency propagation is related to preshoot and overshoot. For example, the linear phase relative frequency transfer characteristics are commonly used to form 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 taps 112a and 112d.

The predetermined gain values of the amplitude control devices 114a and 114d were chosen to be the same, and the time intervals T ₁ + T ₂ and T ₃ + T ₄ are equal to the prephase relative frequency transfer characteristics as evident by the same preshoot and overshoot. The same was chosen to result. The amplitude control signals associated with taps 114a and 114d are controlled to generate unequal preshoots and overshoots to compensate for phase-to-frequency nonlinearities in other parts of the video signal processing system.

It is preferable to change the position at the peak amplitude frequency of the amplitude versus frequency transfer characteristic of the brightness channel of the television signal processing apparatus. FIG. 5 is a schematic diagram of a signal processing unit useful for light channel 16 of FIG. 1 to control the bandwidth and peaking characteristics of light channel 16, similar to the signal processing unit 36 of FIG. 1, and this signal processing unit is in addition to its amplitude. Includes equipment for controlling the frequency variation of peak amplitude of large frequency transfer characteristics.

The numbers and numbers in FIG. 5 are the same as the signals and components in the signal processing unit 36 in FIG. In order to form the signal processing unit of FIG. 5, the modification of the signal processing unit 36 of FIG. 1 is represented by the numeral of 500 units in FIG. Because of the similarity between the signal processing unit 36 of FIG. 5 and the signal processing unit 36 of FIG. 1, only the differences between the two devices will be described in detail. Similar parts of both devices operate and planet in the same way.

Two additional taps 512X and 512Y are coupled to delay line 110 'to form delayed video signals X and Y to determine the peak amplitude position of the amplitude versus frequency transfer characteristic of the signal processing unit of FIG. Delayed video signal X is delayed with respect to delays of T ₅ greater than the delay of the input video signal V _i 'that is, the delayed video signal a' by the time interval T _D '+ T _5. Delayed video signal Y is the time interval T _D '+ T ₁ ' + T ₂ '+ T ₃ ' + T ₄ '-T ₆ with respect to the delay of T ₆ less than the delay of V _i ', ie the delayed video signal d '. Delayed by. The time interval T ₅ is shorter than the time interval T ₁ ′. The time interval T ₆ is shorter than the time interval T ₄ ′.

Delayed video signals X and Y are applied to amplitude control devices 514X and 514Y, respectively. The amplitude control devices 514X and 514Y are formed in a similar manner to the amplitude control devices 114a ', 114b', 114m ', 114c' and 114d '. The amplitude control output signals of the amplitude control devices 514X and 514Y are applied to the addition circuit 516, where they are added logarithmically to form V _P1 . In a similar manner, the amplitude control output signals of the amplitude control devices 114a 'and 114d' are applied to the addition circuit 518 which is added logarithmically to form V _P2 .

Both adders 516 and 518 are planetary in a similar manner to adder circuit 118 '. As can be seen with reference to FIG. 6, the amplitude versus frequency transfer characteristic associated with V _P1 has a peak amplitude at a frequency greater than the frequency position of the peak amplitude of the amplitude versus frequency transfer characteristic associated with V _P2 .

Signals V _P1 and V _P2 are applied to mixer unit 520 along with control signals such as color killer signals or chromatic bandpass signals. Mixer unit 520 is used to combine the controllable amplitude portions of V _P1 and V _P2 to form V _P3 in response to the control signal. Mixer unit 520 is formed in a similar manner to mixer unit 112 '. Mixer unit 520 is adjusted to switch V _P3 between V _P1 and V _P2 in response to a control signal representing an undesirable signal amplitude present in the brightness channel. Thus, for example, when the color signal indicates a relatively large amount of color information, V _P3 will be equal to V _P2, and the signal processed by the signal processing unit of FIG. 5 is due to the enhancement of the undesirable signal present in the brightness channel. It will be peaked at a relatively low frequency to avoid the occurrence of one undesirable pattern. Conversely, when the control signal indicates a relatively small amount of color information, V _P3 will be equal to V _P1, and the signal processed by the signal processing unit of FIG. 5 will be peaked at a relatively high frequency.

The signals V _P3 and V _bw2 ′ are applied to the addition circuit 522, where V _P3 is algebraically subtracted from V _bw2 ′ to planet V _P ′. Adder circuit 522 is formed in a similar manner to adder circuits 516 and 518.

In the operation of the signal processing apparatus of FIG. 5 to be described by way of example, the tabs 112a ', 512X, 112b', 112c ', 512Y' and 112d 'are symmetrically positioned around 112m' and have a time interval T ₁ ', T ₂ '+ T ₃ ' and T ₄ 'are both equal to 1 / 2f ₂ , where the frequency of the signal component of the composite video signal V ₁ that is undesirably present in the f ₂ brightness channel. Furthermore, for example, the predetermined gain values of the amplitude control devices 114a ', 514X, 114b', 114m ', 114c', 514Y and 114d 'are respectively 1/2, 1/2, 1, 1/2, 1/2 And a relative value of 1/2.

FIG. 6 shows the amplitude versus frequency transfer characteristics associated with V _P3 , V _bw2 ′ and V _P ′. The amplitude versus frequency transfer characteristic associated with V _bw2 ′ is a cosine function with a pulsation rate of 4f ₂ . Amplitude versus frequency transfer characteristics associated with the V _P3 is a state diagram of when V _P3 is equal to, V _P3 is equal to the V _P2 and V _P1. When V _P3 is equal to the V _P2, amplitude versus frequency transfer characteristics associated with the V _P3 is a cosine function having a minimum amplitude in the 4f _2/3 vein tied, and 2f _2/3. When V _P3 is equal to _P1 and V, amplitude versus frequency transfer characteristics associated with the V _P3 becomes a cosine function having the minimum amplitude of the 4f _1/3 vein tied, and 2f _1/3 in.

The frequency f ₁ is determined by isolating in time between the delayed video signals X and Y.

In particular, the time delay between the delayed video signals X and Y is equal to 3f _1/2 .

The amplitude band frequency transfer characteristic associated with V _P 'is formed by subtracting the amplitude band frequency transfer characteristic associated with V _P3 from the amplitude band frequency transfer characteristic associated with V _bw2 ′.

The amplitude versus frequency transfer characteristic associated with V _P 'is shown when V _P3 is equal to V _P1 and V _P3 is equal to V _P1 . The peak amplitude of the amplitude versus frequency transfer characteristic associated with _P V ', when _P3 is equal to V and V _P2 are located at approximately 2f _2/3. When the V _P3 be the same as V _P1, the peak amplitude of the amplitude versus frequency transfer characteristic related to V _P 'is located at a frequency of 2f _1/3 than 2f _2/3.

Therefore, since V _P 'determines the peaking characteristic of the signal processing unit of FIG. 5, the peak amplitude position of the amplitude versus frequency transmission characteristic of the signal processing unit of FIG. 5 is controlled by controlling the formation of V _P3 . In particular, when the control signal representing the amount of color information present in the video signal indicates a relatively large amount of color information, V _P3 constitutes a combination of two delayed video signals X and Y having amplitude-to-frequency transfer characteristics at a relatively low frequency peak amplitude of the main line. .

When a signal representing a color information present in a video signal indicates a relatively small amount of color information, V _P3 constitutes a combination of two delayed video signals a 'and d' having an amplitude-to-frequency transfer characteristic with a relatively high frequency peak amplitude. do.

Claims (1)

As described herein and shown in the drawings, a video signal source, a signal delay device coupled to the video signal source, a plurality of signal coupling devices coupled to the signal delay device for generating a plurality of delay video signals, and At least a first separated at timely isolated at time intervals substantially equal to NT / 2 (T is the duration of the predetermined signal component applied by the signal source and N is an integer greater than 1) to generate a first combined signal. And a first device for combining a second delayed video signal and a device for deriving a first bandwidth determination signal from a third delayed video signal located between the first and second delayed video signals on time. A signal processing apparatus comprising: a field for deriving a second bandwidth determination signal from fourth and fifth delayed video signals located between the first and second delayed video signals on time; And a second device for combining the first combined signal with the bandwidth determination signal to generate a second combined signal, and a controlled amplitude portion of the first and second bandwidth determination signals. An apparatus for selectively combining the first and second bandwidth determination signals to generate a three bandwidth determination signal, and a second means for combining the third bandwidth determination signal and the second combined signal to generate an output signal; Automatic brightness channel frequency response control device comprising three devices.

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