DE1762241C - Circuit arrangement for setting the hue on a color television set for a line-sequential color television system - Google Patents

Description

The invention relates to a circuit arrangement for setting the color tone on a color television set for a line-sequential color television system, wherein a color television signal consists of a luminance signal, two line-sequential color difference signals and one during the horizontal sync signal section transmitted color burst exists.

Such circuit arrangements for line sequencing Color television systems are known (German Auslegeschrift 1 161 305). In line sequential color television systems cannot adjust the hue in the traditional way by changing the phase of the Reference carrier can be changed to the color difference signal.

It is the object of the invention. a similar adjustment effect to the hue adjustment in a simple manner to achieve.

This object is achieved according to the invention in that the demodulated color difference signals - .V.

- Z are each fed to an amplifier as well as a ± KO ^ eration amplifier, where K is a factor between + 1 and - 1. that the output signals of the amplifier for the -X or -Z signal and of the ± ^ operational amplifier for the -Z or

- A 'signal are fed to an adder stage and that adjusting elements are provided for changing the relative signal components in the sum signal -X ± K [-Z) or ~ Z ± K (-X) . This gives a simple color setting which is easy to implement in terms of circuit technology and which corresponds in its effect to the known one and which is fully satisfactory.

Suitably, the adjusting members for setting counter ⁶ S-sensed are coupled. The setting is then even more simplified.

Easily variable resistances can be used as setting elements. One has such a special one simple circuit.

It must be pointed out that opposing Wid '^ wndsänderunaen known for the color setting in itself (German Auslegeschrift are 1 in 78 S92l

In the drawing Ut the invention is explained, for example, namely shows

Fi "! A graphic representation of the DemoduTauun of an NTSC color television signal.

Fiü. 2 is a graphic representation of the invention Color adjustment.

F i c. 3 shows a block diagram of the circuit arrangement "for the color adjustment according to the invention

F i ii. 4 shows the circuit of an operational amplifier for the Schaiiur.üs arrangement according to FIG. 3.

A color treacher. for example by quadrature modulation of a carrier with two color signals is required in demodulation in one Recipient a reference point serving as a reference carrier. In the NTSC system, a composite color signal, for example, is required to meet this requirement eight similar reference carrier vibrations. the .m the back porch of the horizontal type, -chronsianals can be used as a color sync signal.

A continuous reference wave is formed in the receiver with the help of this synchronous color signal. s.- _: that you get a synchronous demodulator. At this point in time, the phase is shifted with respect to the color sync signal reference phase, and the V and Z color difference signals are demodulated instead of the two transmitted color differentiators / signals / and Q.

It is known that in the NTSC color television system the / and 0 corresponding color subcarrier frequency color difference signals. which is due to a color demodulator is given by

R-Y B - Y.

_{T |} - ₄ _ cos .. ", + .. _15rS , n ... _l r.

where. ^ the angular frequency of the color reference carrier. Y the luminance signal given by

Y = COOK + 0.59 G + 0.11 B

and RG B are the respective chrominance signals. It is now assumed that the reference carrier applied to the demodulator is represented by E sin (») _5. ' + <-)) is given. which leads by ^ the phase (■) in relation to the reference carrier modulated with the color difference signal (ß-Y) / 2, O3. The color difference signal appearing at the output of the demodulator is then given by

D y *

+ -, TIT " ^{sin H} ■

For example, (-) is given by W_, = 260.5 ° and fi »_. = 203 ', the demodulation outputs are - X and - Z. This shows a function that corresponds to that of a receiver with XZ demodulation. For the color setting on the receiver, the hue is changed by changing the ratio of the demodulation outputs RY and BY by changing θ_ _χ ± λθ and (■) .. ± A (·) , where (-> _ _x - < y_. is kept constant.

η y

indicates that the phase of the reference carrier can be changed in the receiver.
F i 2. 1 time

R - Y

B-V

expressed in (-) near the - .V and - Z demodulation outputs. From this one can determine the relationship between the phased of the reference carrier and the demodulator output.

In the line sequential system, the hue adjustment cannot be achieved by changing <-) . because one works with signals that are obtained by demodulating>: .V and 2 or V. / and O. However, a setting effect similar to the color ion setting by changing fi can be obtained by using the following system:

F i g. 2 shows -X ± K for the -Z signal and id -ZK for the -A 'signal.

A comparison of FIGS. 1 and 2 result in the following:

RY
the expression - sin (-> for - Λ 'and -Z grows

with increasing H in the vicinity of <-) _ _x and · «... on which -A 'and -Z depend, where ---- j- sin (-> ne-

is negative. while the expression _, ~ ■ cos H for

- .V and - Z decreases towards zero. The general tendency of the F i g. 1 and 2 remain the same for - A '± K (Z \ with regard to the changes in the positive value of K , and -Z = Ki-X) is demodulated with that at f -) _ _x or l ·! ... —X and - Z mixed. Since the differential coefficients of sin <·) and cos (-> have different values in the vicinity of <-> = 180 and 270, the above does not occur. Rather, the differential coefficients are small, and therefore the degree of change is also small, so that With the signal treatment method described above, a hue adjustment similar to that in the receiver can be achieved by the circuit operations corresponding to -X ± K ( -Z) and -Z + K (-A'1.

F i g. 3 shows a circuit arrangement constructed for the above purpose. An amplifier 65 and 66 and, in addition, a ± ^ operational amplifier 67 and 68 are connected to connections 63 and 64. The output signal of the ± K operational amplifier 67 or 68 connected to the other terminal 02 or 64 is added to the output signal of one of the amplifiers 65 or 66 in an adder stage 69 or 70, respectively. There are between the adder 69 or 70 and the ± K operational amplifier 67

and 68 respectively adjusting members 71 and 72 respectively connected between them, which are expediently used as variable resistors are executed. The sum signals obtained as output signals of the adder stages 69 and 70, respectively are connected to terminals 73 and 74, respectively.

ίο F i g. 4 shows an embodiment for a ± ^ 'operational amplifier. Output signals of opposite polarity occur at the emitter and collector of a transistor. For the adjustment members as Tl and 72, variable resistors used

booths of 10 kiloohms are preferably used. If the movable tap of these variable resistances is fixed in the middle, then the outputs of the ± K operation amplifiers 6 "? And 68" are zero. "

At the connections 63 and 64 of the circuit arrangement are now. as in Fig. 3 indicated, demodulated color difference signals - X or - Z given, for example, the output signals of the clamping circuits of the decoder of a color television

represent the recipient. The color difference signals - ν and - Z thus represent the input signals of an amplifier 65 or 66 and a ± K operational amplifier 68 or 67. The color difference signals are only amplified in the amplifiers 65 and 66. The output signals of these amplifiers 65 and 66 are given directly to the addition stage 69 and 70, respectively. In the ± ^ operational amplifiers 67 and

68 an output signal ± K {- Z) or ± K {- X) is formed from the color difference signals, the respectively

via an adjusting member 71 or 72 to an adder stage

69 or 70 is given. The desired signals - A '± K (- Z) or --Z ± K (-X) are thus obtained at the end terminals 73 and 74. By coupling the setting members 71 and 72 in opposite directions, one obtains —Z ± K (-X) for -A '± K (-Z).

With the help of this circuit arrangement, a color setting is accordingly possible. Of course, this method can also be used in the same way for R - Y or B - V signals. The line sequential color television system is then fabricated using the circuitry described above. The color encoder can be provided on the transmission side and the color decoder on the receiver side.

1 sheet of drawings

Claims (3)

Patent claims: 1. Circuit arrangement for setting the hue on a color television set for a zeilensequL-ntielles color television system, a color television signal consisting of a luminance signal, two line-sequential color difference signals and one during ι *. Horizontal sync signal section transmitted Farbsvnchronsignal is sawn \ o, characterized in that the demodulated color difference signals - Λ "-. Z are each an amplifier (65 66) and each having a ± K-Operunonsverstärker are supplied (67. 68), where K is a factor between -1 and -1 is that the output signals of the amplifier for the -X or -Z signal and of the ± K operational amplifier for the -Z or -A 'signal are fed to an adding run (69 and 70) and in that adjusting members (71. 72) for changing the rela- -i ven signal components in the sum signal - are provided A '± K (-zl b / w -Z-Ki-X.). 2. Circuit arrangement according to claim 1, characterized in that the adjusting members (71. 72) are coupled for opposing setting. -5 3. Circuit arrangement according to claim 1, characterized in that the adjusting members (71. 72) are variable resistances.