JPS5921182A - Clock generator for picture display - Google Patents

Abstract

PURPOSE:To realize a stable display, by switching the control to an oscillator between just a display of characters, etc. on a screen and the superimposition given on the video signal. CONSTITUTION:A reference oscillator 12 of a color subcarrier has free oscillations. When characters and figures are displayed, the oscillating frequency is decided for a display clock oscillator 11 after a phase comparison carried out with the oscillator 12. While the oscillator 11 undergoes a phase comparison with the horizontal synchronizing signal sampled by a synchronizing/separating circuit 6 for decision of its oscillating frequency in case the characters and figures are displayed with superimposition on the video formed by TV signals. In this case, the oscillating frequency of the oscillator 12 is fixed by a loop of a burst separating circuit 3 an APC phase wave detector 7 the oscillator 12 the detector 7. Thus a stable display is ensured despite a change of the horizontal synchronizing signal due to a ghost.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to an I-cock for displaying image data sent in the form of digital signals on an image display device such as a cathode ray tube. The present invention relates to a cock color generating device for stably extracting images according to the display mode and for displaying pictures in the order of pictures.

[Background technology of the invention]

In recent years, systems such as text broadcasting have been introduced in which image information is inserted as a binary digital signal into the video signal sent to the antenna or telephone line of television broadcasting, and each terminal receives and displays this signal. being developed. The above digital signal (J is once stored in the image memory in the television receiver, which is a terminal device, so in order to display it, the stored image data must be read out. The address for viewing this image data is The signal is a clock pulse for the display which determines the height of the display screen.
28Jl, ') i%oj1, tsu, tsu 2.7. □Yo.
The color subcarrier on the transmitting side taken by the A3 C circuit is output from an oscillator (VCO) whose ocular frequency is controlled by a DC voltage. The phase is detected by a phase detector, and the voltage corresponding to the phase difference is smoothed by a division circuit. After that, it is input to the frequency control terminal of the VCO and synchronized with the color subcarrier on the transmitting side from the output 91M of the VCO. A color subcarrier f'sc is created on the receiving side, and phase detection is performed between this color +1+1 general transmission wave fsc and a freely oscillated display clock CI), and the display clock CP@ is generated at a voltage according to the phase difference. This is achieved by making the oscillator with a side diameter of 1'.

In this way, the phase-locked color subcarrier f in the Al)C circuit
The display clock CI) stabilized by a frequency control loop that further locks the phase based on sc is
The phase will be synchronized with the horizontal synchronization signal, and images such as characters and figures will be displayed from a predetermined position on the display screen.

However, both 1-. displayed on the image display device:
: Xu Gj, a fixed display in which a stand and a single screen for displaying an image based on a normal video signal are displayed using the digital signal, and a fixed display based on a video signal based on a digital signal. There are cases where images such as characters and figures are displayed with superimposed light (hereinafter referred to as -F super display). When performing this super display, when receiving a black and white broadcast in which the video signal does not include the verse 1 signal, or when the verse l signal is disturbed due to a weak electric itching condition, →-strike □ phenomenon, etc.9! The ffl' indicating lj pulse CP is not generated stably, and its relationship with the horizontal synchronizing signal is unstable! [Su ((The display position when displaying is not determined,
In addition, when a weak electric field state or a gosme phenomenon occurs, the frequency of the color subcarrier oscillator synchronized to the burst by the AJ'C circuit changes, causing color shift on the text/graphic information screen. There were also drawbacks.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and is suitable for use in pre-visit broadcasting signals, etc.) when characters, letters, letters, letters, etc. are mixed on the same screen on the same screen. , the display clock is pre-visited in the case of a fixed display that only displays text/figures; The purpose is to provide a generator.

[(11' of the invention is also required]) In other words, the present invention, when character/graphic information is to be fixedly displayed on the entire television screen, tree-oscillates the color j'+ll carrier wave and uses this freely oscillated color sub-wave. Oscillating the display clock based on the carrier wave in phase 1
- Even if the hearth signal is disturbed due to the influence of the shade, it will still be displayed 1
When super-displaying text/graphic information on video using a television signal, the color subcarrier is generated in phase synchronization with the verse 1 signal, and the display clock is By generating in phase synchronization with the horizontal synchronization signal obtained from the synchronization circuit, the character -
It took 120 years for the display position of graphical information to be accurately determined.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the drawings with reference to embodiments. In the figure, the division number is taken into input J-J end A1,
Display clock CP, color sub-1 general transmission wave fsc 1,
These signals output to the output 4M element 2 a character-graphic signal or a video signal based on a television broadcasting signal, or (A) indicates that a composite signal in which these character-graphic signals and a video signal are placed directly is output. This is a 1" clock pulse generator for display.The display clock CP is a color subcarrier rS.
Set the frequency to 815 times c.

The television signal at input terminal l is from 1 to (1
The signal is supplied to a circuit 3, a display mode detection circuit 4, a character/figure signal reproduction circuit 5, and a synchronization circuit 4 and a separation circuit 6, respectively.

The burst separation circuit 3 has a horizontal period Ilr! The signal is extracted to the berth 1 inserted in the back board of the number, and the extracted parse 1~ signal is supplied to the APC phase detector 7.

The display mode detection circuit 4 detects the display method from the text/graphics 1n information superimposed on the television (i);
Detects the mode and switches the first switch 8 and p according to the display mode.
ry 2 Su-r Tsuji9, l'yo3 Su4 TsuchilO
I'm trying to control it. 5, the frequency of 1 clock C1) is displayed.
A VCO that oscillates a frequency 2 (c1+) with twice the frequency of Qfcp (14) is generated, and when no control voltage is applied to its voltage control ψ11.1 child, a tree oscillates near 2 rCp. Similarly, the color The reference oscillator 12 for the subcarrier is also constituted by a VCO, and free oscillates near fsc when no control voltage is applied.

When detecting the fixed mode in which characters/figures' time signals are fixedly displayed on both sides of the television, the display oscillator 1 compares the phase with the free oscillation output of the reference oscillator 12 to determine the number of oscillation stations 1. be done. That is, this E() matching reference oscillator 12 → first phase comparator 13 → display 1 cock oscillator 11 → first frequency divider 14 → f;r+y 1 phase comparator 1
3 constitutes a first phase-locked loop, and this alT l
The phase of the oscillation frequency of the optical clock excavator 11 is fixed by the loop.

Next, when character/graphic information is detected by the television signal, the display f cock oscillator 11 compares the phase with the horizontal synchronization signal extracted by the period separation circuit 6.
The F8 wavenumber is determined. In other words, synchronous branch 1 circuit 6 → 2nd
Phase comparator 15→Display■Cock oscillation);;÷11−+
2nd frequency division JIJ] 16 → 2nd phase comparison: (The EB2 phase-locked loop is constructed from the feather 15, and the 4th round circumference 1'1M number of the cock oscillation ring IJ is The phase is fixed. At this time, the base 11μ oscillator 12 of the color sub-general transmission is connected to the pulse 1-separation circuit': I→Al)
C (N'1 phase detector 7 → Ji・(additional 1 phase detector 12 → Al)
C position a wave generator 7 (7) The oscillation frequency is fixed by the APC phase-locked loop.

so that a frequency signal equal to is derived? . C is there. Further, the frequency division ratio of the second frequency division H:tt6 is divided by 1/72E3, and the horizontal opening 1[j
) A signal rn' having the same frequency as the signal fH is derived. Further, the synthesis circuit 17 is a circuit that colors text/graphic information by mixing the color subcarrier fsc with Il, G, I1 color Ijlt, and JTL reproduced by the text/graphic signal reproducing circuit 5. stomach).

If the above 4'i'/configuration is J:Jl, the display IJts CI' in the fixed mode is 81'l, ]The frequency is divided by the frequency divider f, and the frequency is approximately equal to the color sub-general transmission wave fsc. Esc' (a). When this happens, the third step (', 7th 10 is the contact piece 1
Since the 84N'2 switch 9 is connected to the contact piece 9a side, the frequency signal -Pirsc
' and (116 outputs from 120 oscillators are input to the first phase detection;!:: J:3.) of (if'
4U is detected as r
jr;'I! ii Even if the oscillation frequencies of I and J are set 11 and the television signal exhibits a weak electric field state or a Gorse 1 phenomenon, the output between the oscillations of the reference oscillator 12, which is freely oscillating, will be affected. It is always synchronized with the 1st and 1st notch CJ for display without being influenced by the 1st and 1st notches CJ).

Therefore, color shift will not occur when the colors are displayed.

Next, in the super display mode, the first switch 8 is connected to the F+'+, L, the second switch 9 is connected to the contact piece 91), and the third switch 10 is connected to the jp:H If)l)
Connect the signal to the side. This signal flI' is the second
(s'L: lIl l Manually inputted to the wide wave generator 15 and supplied from the synchronization component ++S circuit 6) Horizontal synchronization signal f
lI and phase detection, It, second rX'l phase (Φ wave detector 1
An output voltage of 5 is applied to the display clock generator, and the 'display clock yct' always becomes a signal synchronized with the horizontal open IJJIi'. Therefore, if the television signal is affected by ghosts etc., the horizontal periodic signal ri
Even if r changes accordingly, this will display H1 or LJ
Since the cock P also follows, it is possible to eliminate the disadvantage that the character/graphic information σ) (/, p indication 11γ1111 is repeated. At this time, the base 7L oscillator 12 is a normal AI)C
The oscillation frequency is fixed by the loop.

〔Effect of illumination〕

As explained below, according to the present invention, in the case of a fixed display and in the case of a super display, the transmitter 1 and 7 are synchronized with the freely oscillated color 1 transmitter. (Since the system is 111i1, the display Utsuku is σ for characters, 1-1, etc.)
ta @ use folded bark! 1. Fixed display character information (I4) does not cause color shift due to signal disturbance, and super display does not cause image shift because the display position is not determined.・)16
It can be reproduced that there are 11 mouths,
.

Claims (1)

[Claims] Superimposing data related to characters, figures, etc. that are multi-electronic in the transmitted video signal on the video signal and displaying it on the display device of the television receiver, and A device that generates one display clock necessary for fixedly displaying a display includes a voltage-controlled display clock oscillator that oscillates the display clock, and a voltage-controlled display clock oscillator that oscillates the display clock, and a voltage-controlled display clock oscillator that is synchronized with a burst signal extracted from the video signal. a base v(f-oscillator capable of oscillating a color subcarrier; a first phase detector for phase-detecting the display clock and the output of the phosphor sub-oscillator independently oscillated in a fixed display mode; It is composed of a second phase detector that detects the phase of the horizontal synchronization signal and the display clock in the superimposed display mode, and detects the oscillation frequency of the display clock oscillator in the fixed display mode. An image display clock generation device, characterized in that it is controlled by the output of a wave detector, and in a superimposed display mode, it is controlled by the output of the second phase detector.