DE1279070B - Color bar generator for color television receivers working according to the PAL system - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

H04n

German ,: 21 al -34/31

Number: 1279 070

File number: P 12 79 070.4-31 (G 46696)

Filing date; April 27, 1966

Open date: October 3, 1968

For setting and checking a color television receiver, in contrast to the black and white receiver two video test images required. Adjusting the convergence (of the three electron guns of the color picture tube) requires a grid (white lines on a black background) as well as the color bar signal for checking the color subcarrier oscillator, its synchronization and the color demodulators.

In the NTSC color television system, m is relatively easy to generate a color bar signal. All that is required for this is a quartz oscillator which oscillates at the sum or difference frequency of the color subcarrier and line frequency. By blanking the oscillation against this oscillator with vertical bars and the synchronous mixture, a color-image-blanking-synchronous signal (FBAS signal) suitable for testing purposes is obtained, the color sequence of which is derived from the well-known circular diagram ^ - the so-called color clock - - results. The color television receiver synchronizes the color subcarrier oscillator by means of its own color sync signal;

There is also a circuit arrangement for generating three video-frequency color signals (German * - sches patent 1168 478), which is made up of rectangular individual pulses of predetermined duration and phase position and on the screen of a color television receiver as color bars can be made visible, For this purpose, a voltage generator taken from a staircase, periodically recurring staircase voltage supplied to several electron beam switchgears, in which by comparison with a selector voltage of certain amplitude rectangular Irripulses are obtained from which by circumcision three color signals can be acquired. The arrangement is particularly suitable for generation of color signals, as they are required in the context of the NTSC system,

Oath of other Farbbalkengöber (»Rundfünteehnische Mitteilungen «, 1965, pp. 135 to 144) is based on the following principle. A chain of bistable Vibrators produce a horizontal frequency of tastini pulses, which are connected to a series of distributor stubs, each of which is exercised assigned a specific color. This Fafbbalkengeber is like the one previously described with your Naöhteil afflicted that the Schaltüngskosten is relatively large.

For the PAL color television system, this method is not suitable. While with the NTSC system, the phase in the circle diagram always rotated in the direction of rotation Color bar generator for according to the PAL system working color television receivers

Applicant:

GRUNDIG E. M. V.

Elektfo-Meohanische Research Institute,

Mh. Mäx Gruttdig, 8510 Fürth, KUrgartenstr. 37

Named as inventor:

Karl Reinmann, 8510 Fürth;

Horst Weglehner,

Wolfgang Singer * 850Ö Nuremberg

remains the same, reverse the direction of rotation in the PAL system ¹ from line to line. In addition, the phase position of the color sync signal jumps by 90 °.

The invention has set itself the task of creating a possibility for the PAL system with which is almost as easy as with the NTSC system a composite signal can be generated.

In principle, karin regards the task as solved If it succeeds, the oscillations of two oscillators, one of which is on the sum frequency And the other oscillates on the difference frequency of the color carrier and line frequency, alternately from line to line to give a common output and to ensure that the Phase position of the vibrations type of point of the line sequence where the color sync signal is located, from Jumps line to line by 90 °.

So one could proceed in such a way that one works with two crystal oscillators, one of which oscillates on the suffix frequency of color carrier ¹ and line frequency, the other on their difference frequency. During the Hörizontal synchronizing pulse, which is generated in a line frequency oscillator, the phases are dör two vibrations vergliöhen and one of the crystal oscillators z. B. readjusted by a capacitance diode in the sense that the phase position to the beginning of the line is always the same. A pulse with half the line rate then alternately sends the sum frequency and the difference frequency to the output. And ait vertical bars and the synonym mixture blanked out.

This solution is relatively expensive because it tight only two crystal oscillators, also sondeftl

809 619/368

a complicated phase comparison and retuning of which the divider 2 has a reduction ratio circuit required. In addition, with this of 1: 625, the divider 3 achieves a reduction ratio Signal generation the color sync signal does not have a 90 ° of 1: 2. In the one following divisor 2 Phase difference. So it does not fulfill the condition- Stage 4 becomes the signal for the vertical synchronizing, that to a simple color bar encoder to put 5 impulse and in a further stage 5 in a balance are. line pattern further processed. The divider 3 He-Eine similar, also with two on the summert with the level 6 the horizontal sync pulses men- and ■ difference frequency of color carrier and and with level 7 a vertical line pattern. Verti line frequency oscillating oscillators provided kal-synchronous pulses and horizontal-synchronous arrangement for a rainbow generator after the io pulse together result in a level 8 the Syn-PAL standard is in an older patent (German chrongemisch, the one with the horizontal and vertical patent specification 1258 449). The exit right lines of stages 5 and 7 blanked in one voltages of the two oscillators are level 9, the BAS signal in the form of a grid an electronic device that switches at line frequency. In reality, this grid appears with Switch fed to the receiver. 15 white lines on a black background, but here it is While in the older patent the two are constantly swinging with black lines on white for the sake of simplicity Oscillators must be crystal-controlled, as shown.

sen and the relationship to the clock frequency over As far as these details are concerned, the circuitry phase dependent rectifier is made, device not much different than that of a normal picture goes the arrangement according to the present invention 20 pattern generator. The novelty is that the square wave generator in the divider 3 is controlled by a quartz crystal to the single line frequency with double the line frequency, and the two set square wave, whose course in the slide start-stop oscillators are each determined by the grams I of the F i G. 2 is shown, is converted in a bistable positive leading edge of two in a bistable len divider 10 in two complementary square wave dividers generated complementary square waves of 25 _with half the line frequency. This half the line frequency for the duration of a line to square waves, the course of which is stimulated from the diagram oscillations. men II and ΙΠ results, are two separate start-The invention brings a much better stop oscillators 11, 12 supplied by the solution. positive leading edge of the square wave to oscillate using a preferably double and can only oscillate freely as long as the square wave oscillates at a line frequency - the square wave lasts. At the outputs of the quartz oscillator with two dividers to generate a start-stop oscillator, there are alternating image synchronizing signals with a scales derived therefrom, ie lines 1, 3, 5 ... or 2, 4, 6 ... and one of the corresponding lines Horizontally synchronous, with the square wave 100% amplitude pulse with vertical line 35 modulated HF oscillations derived therefrom, the course of which shows the pattern of which the synchronous signals are stylized as shown in Diagrams IV and V. In a mixed keying required synchronous mix and in connection stage 13, these signals, which always begin with the line pattern with this line pattern the BAS signal chen phase position, merged (cf., it is proposed according to the invention, the diagram VI) and in a blanking stage 14 with the 40 synchronous mix of stage 8 derived from the horizontal sync pulse stage and a vertical square wave single line frequency with the help of a bar pattern, derived from stage 7, blanked, a bistable divider into two complementary right - which creates the desired composite signal to convert the corner waves to half the line frequency. This diagram VII shows. With a switch 15 square waves can then be fed to two separate optionally the composite signal of stage 14 or the start-stop color carrier oscillators, ie 45 BAS signal of stage 9 to a video amplifier oscillators, which are given by the positive leading edge of 16 or to modulate an RF oscillator "square wave to vibrate and only free gate 17 are used.

can oscillate as long as the square wave lasts. The frequency of these start-stop oscillators generated color subcarriers during two successive cycles is selected so that within a line period 50 following lines can be seen from the circle diagram of one phase at the time of the color synchronization signal. In this diagram, let the difference of 45 ° and, at the end, at least 360 ° outer circle show the phase progression of the oscillations supplied by the oscillator with respect to the color carrier oscillator in the receiver 11, the inner circle results in the. The start-stop oscillators that are leading and lagging at the outputs of the color carrier of the oscillations of the oscillator 12 are so leading and lagging that the outer circle contains lines 1, 3, 5 ..., the lines alternating with the square wave inner the lines 2, 4, 6 ... At time t ₀ , 100% amplitude-modulated and with the same beginning of the horizontal sync pulse, the RF oscillations starting from the phase position are exactly the oscillation generated by the oscillator 11 and are brought together in a mixer and in phase in the color carrier. After about 7 μβ, the middle of a blanking stage with the synchronous mixture and 60 times longer color sync signal time, a phase under a vertical bar pattern is blanked, which means that the difference between + 45 ° can be measured. While the line desired composite signal is received. The phase difference progresses in the clockwise direction - the invention and its details are continued in the sense and is explained in more detail because of the following in comparison to the following with reference to the drawings. len frequency higher frequency beyond 360 °, up to In the block diagram of FIG. 1, 1 of 65 after 64 μβ a phase rotation of + 405 ° is indicated. At this point in time, the oscillator 11 is generated at twice the line frequency. The and the oscillator 12 switched on. The phase rotates square wave gets to two divisors 2, 3, turns counterclockwise, and after about 7 y &

a phase shift of -45 ° is reached, after μβ a phase shift of -405 °. So it will receive a color sync signal that jumps from line to line by 90 °, while a line is running but covered the entire color spectrum.

Claims (1)

Claim: Color bar generator for color television receivers working according to the PAL system, preferably with one with a square-wave crystal oscillator oscillating at twice the line frequency two dividers for generating a vertical sync pulse with a horizontal line pattern derived therefrom and a horizontal sync pulse with a vertical line pattern derived therefrom, of which the sync signals the sync mix required for blanking and in connection with this the line pattern the BAS signal result, characterized in that the horizontal syn- ao chronimpulsstufe (6) derived square wave single line frequency with the help of a bistable Divider (10) is converted into two complementary square waves of half the line frequency, the two separate start-stop color carrier oscillators (11, 12) are fed, their frequency is chosen so that within a line period at the time of the burst signal a phase difference of 45 ° and at the end at least 360 ° compared to the color subcarrier oscillator results in the receiver, and that at the outputs of the leading and trailing the ink carrier Start-stop oscillators (11, 12) alternating with the square wave amplitude-modulated and color carrier frequencies beginning with the same phase position Vibrations are brought together in a mixing stage (13) and in an output stage (14) with the Mixed sync signals and a vertical bar pattern are blanked. Considered publications:
German Patent No. 1168478;
Rundffunkechnische Mitteilungen, 1965, H.
, 135 to 144. Legacy Patents Considered:
German Patent No. 1258 449. 1 sheet of drawings 809 619/368 9.68 © Bundesdruckerei Berlin