CN1179677A

CN1179677A - Composite video signal generator

Info

Publication number: CN1179677A
Application number: CN 97118474
Authority: CN
Inventors: 裴点汉
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1996-09-18
Filing date: 1997-09-17
Publication date: 1998-04-22

Abstract

The present invention is provided a composite video signal generator, which can be simply implemented using an application-specific integrated circuit (ASIC). The generator includes an oscillator which generates a clock signal, a color burst generator, a color signal generator. A luminance signal processor is provided which receives luminance data and which converts the luminance data in an analogue luminance signal. A clock signal generator receives the colour control signal and the clock signal and outputs the first, second and third control signal and an S-signal. The luminance data which are included in the colour signal are output to the luminance signal processor. A mixer mixes the burst, the colour signal, the luminance signal and the S-signal and outputs a composite video signal.

Description

Composite video signal generator

The present invention relates to composite video signal generator, and be particularly related to the composite video signal generator that is used for producing the composite video signal of shielding the background images of going up demonstration (OSD).

As shown in Figure 1, be used to shield the composite video signal of background images of demonstration (OSD) generally by receiving rgb signal from digital integrated circuit IC1 and using the RGB encoder IC2 that is applicable to broadcast system (for example NTSC or PAL) to produce.This RGB encoder IC2 needs complicated peripheral circuit.So, need a kind of device to be used for producing composite video signal, use this device to produce various colours by purposes.

An object of the present invention is to provide a kind of composite video signal generator, and this generator is fully simple and can realize in single asic chip, and can make to be lower than in the past the cost of RGB encoder.

In order to reach above purpose, according to the invention provides the composite video signal generator that comprises with lower device: the oscillator that is used for clocking; The burst signal generator is used for the frequency of clock signal is carried out frequency division and switched the burst signal of the clock signal of this frequency division with the generation composite video signal according to first control signal; The colour signal generator is used for according to the second control signal phase shifted clock signal, and the clock signal of phase shift is carried out frequency division to produce the colour signal of composite video signal, and wherein phase shift angle is according to color and difference; Luminance signal processor, being used to receive brightness data and changing this brightness data according to the 3rd control signal is analog luminance signal; Regularly/and sync generator, be used to receive color control signal and clock signal, export first, second and the 3rd control signal and composite synchronizing signal, and be contained in brightness data in the colour signal to described luminance signal processor output packet; And mixer device, be used for burst signal, colour signal, luminance signal and composite synchronizing signal are carried out mixing with the result of output as the mixing of composite video signal.

Below by its preferred embodiment is described in detail in detail with reference to accompanying drawing, above purpose of the present invention and advantage will become more obvious.

Fig. 1 is to use the block diagram of the composite video signal generator in the past of RGB encoder IC;

Fig. 2 is the block diagram according to composite video signal generator of the present invention;

Fig. 3 A is the sequential chart of expression from the signal waveform of each module output of Fig. 2 to 3D;

Fig. 4 A is the oscillogram by the signal 4fsc of the oscillator output of Fig. 2; And

Fig. 4 B is the signal waveforms of doing 180 ° of phase shifts with reference to the 4fsc waveform of Fig. 4 A to 4I.

Each label meaning is as follows in the accompanying drawing: Figure 11 numeral IC2 RGB encoder 3 composite video signal Figure 22 0 oscillator 21 frequency dividers 22 timing/sync generators 23 first band pass filters 24 Xiang Yi ﹠amp; Frequency dividing circuit 25 buffers 26 D/A converters 27 second band pass filters 1 composite video signal 2 color control signals

Composite video signal generator shown in Fig. 2 comprises an oscillator 20, a burst signal generator 21s, a timing/sync generator 22, a colour signal generator 24s, a

luminance signal processor

25s, 28, one second frequency mixers 29 of one first frequency mixer and a three-mixer 30.

Among Fig. 2, the clock signal that is produced by oscillator 20 offers burst signal generator 21s, regularly/and sync generator 22 and phase shift and frequency dividing circuit 24.

Wherein, burst signal generator 21s comprises a frequency divider 21 and one first band pass filter 23.Frequency divider 21 is from oscillator 20 receive clock signals, and according to first control signal of coming self-timing/sync generator 22, this clock signal frequency division and output device had chrominance subcarrier frequency f _ScIt is the sub-frequency clock signal of 3.58MHz.23 pairs of signals of being exported by frequency divider 21 of first band pass filter carry out passband filtering, so that output frequency is f _ScSine wave as burst signal.

Regularly/sync generator 22 is from the reception of the external digital circuit such as screen shows (OSD) controller color control signal.Then, regularly/sync generator 22 generation control signal control burst signal generator 21s, colour signal generator 24s and luminance signal processor 25s.And then, regularly/sync generator 22 extracts the brightness data that is included in the exterior color control signal, and to buffer 25 these brightness datas of output.

Colour signal generator 24s receives second control signal of being exported by timing/sync generator 22 and produces the colour signal that phase place is different from the burst signal phase place.Wherein, colour signal generator 24s comprises a phase shift and the frequency dividing circuit 24 and second band pass filter 27.The clock signal that phase shift and frequency dividing circuit 24 receives from oscillator 20, according to second this clock signal of control signal phase shift, and to by the signal of the frequency division of the frequency of this signal of phase shift with output frequency division.The signal that 27 pairs of phase shifts of second band pass filter and frequency dividing circuit 24 are exported carries out passband filtering with the filtered signal of output as colour signal.

Luminance signal processor 25s comprises buffer 25 and D/A converter 26.Buffer 25 storages come the brightness data of self-timing/sync generator 22.The brightness data that D/A converter 26 translation buffers 25 are exported is an analog signal.

The output signal of 28 pairs first band pass filters 23 of first frequency mixer and the output signal of second band pass filter 27 are carried out mixing and are exported these results to three-mixer 30.29 pairs of composite synchronizing signals by 22 outputs of timing/sync generator of second frequency mixer are carried out mixing with the luminance signal of being exported by luminance signal processor 25s, to export these mixed frequency signals to three-mixer 30.And 30 pairs of signals by

first frequency mixer

28 and 29 outputs of second frequency mixer of three-mixer carry out mixing, and export the signal of this mixing as composite video signal.

Now with the operation of the composite video signal generator of key diagram 2 in more detail.

In a preferred embodiment of the invention, oscillator 20 generation frequencies are chrominance subcarrier frequency f _ScFour times clock signal, f in the TSC-system formula _ScBe 3.58MHz.Yet, be noted that clock signal frequency is to be not limited to 4f _Sc.For example, clock signal frequency can be chrominance subcarrier frequency f _Sc2 ^NDoubly, for example 8 frequencys multiplication or 16 frequencys multiplication.

Frequency divider 21 receives from the clock signal of oscillator 20 and by this clock signal of quadruple frequency division, according to first control signal of coming self-timing/sync generator 22 and output frequency f _ScRectangular pulse signal.First control signal control frequency divider 21 is at the suitable timing output f of the horizontal synchronizing cycle of composite video signal _ScSignal.

23 permissions of first band pass filter are from the f in frequency divider 21 rectangular pulse signals _ScComposition passes through, so that to the sine-shaped burst signal of first frequency mixer, 28 output map 3B.

Simultaneously, phase shift and frequency dividing circuit 24 receive 4f _ScClock signal, according to second control signal that comprises colour information this clock signal of scheduled volume phase shift, to being f by this signal frequency frequency division of phase shift according to 45 ° of multiples _ScThe signal of frequency is to export this signal.Here, phase-shift phase depends on the color that will express.The signal of being exported by phase shift and frequency dividing circuit 24 is shown among Fig. 3 C.

In a preferred embodiment of the invention, phase shift and frequency dividing circuit 24 are by 180 ° of multiple phase shift 4f _ScClock signal, with obtain respectively Fig. 4 B to eight signal psi shown in the 4I 1 to φ 8.Then, circuit 24 one of is selected in eight signal psi 1 to φ 8 according to second control signal, and selected signal frequency is carried out frequency division.So the signal of frequency division has f _ScFrequency and phase shift are 45 ° of multiples.

Simultaneously, 27 pairs of signals of being exported by phase shift and frequency dividing circuit 24 of second band pass filter carry out filtering selectively only to allow f _ScFrequency content is passed through.28 pairs of burst signals of first frequency mixer with carry out mixing by the sinusoidal colour signal of second band pass filter 27 output, and to the result of this mixing shown in the three-mixer 30 output map 3D.

Simultaneously, receive the 4f that is produced by oscillator 20 _ScClock signal and from the timing/sync generator 22 of the color control signal of external digital circuit is counted this clock signal and to the composite synchronizing signal that comprises vertical and horizontal-drive signal shown in second frequency mixer, the 29 output map 3A.And, regularly/and sync generator 22 is contained in brightness data in the color control signal to buffer 25 output packets, and this buffer is to D/A converter 26 these brightness datas of output.D/A converter 26 is converted to analog signal to the brightness data from buffer 25, and exports this analog luminance signal to second frequency mixer 29 as luminance signal according to the 3rd control signal of coming self-timing/sync generator 22.29 pairs of these luminance signals of second frequency mixer are carried out mixing with the composite synchronizing signal shown in Fig. 3 A that comes self-timing/sync generator 22, and export by this signal of mixing to three-mixer 30.Carry out mixing from the signal of first frequency mixer 28 and the signal of being exported by second frequency mixer 29 shown in 30 couples of Fig. 3 D of three-mixer, and export the signal of this mixing as composite video signal.

Here, the colored number that can be expressed depends on the possible number of levels of being exported from D/A converter 26 of luminance signal.For example, if 8 class signals by 24 outputs of phase shift and divider circuit are arranged, each class has 45 ° phase difference, and D/A converter 26 receive 4 brightness data with output have 16 may level luminance signal, then can obtain 128 kinds of colors.So,, just can increase number of color by increasing number of phases or the possible level number of luminance signal.By fast processing data in buffer 25 and in phase shift and frequency dividing circuit 24 fast translate phase just can handle the figure of complexity.

Thereby according to the present invention, the simple circuit that use can realize in single asic chip can be easy to produce versicolor composite video signal.And avoided complicated peripheral circuit.

Claims

1. composite video signal generator comprises:

The oscillator that is used for clocking;

The burst signal generator is used for the frequency of clock signal is carried out frequency division and changed the burst signal of the clock signal of this frequency division with the generation composite video signal according to first control signal;

The colour signal generator is used for according to the second control signal phase shifted clock signal, and the clock signal of phase shift is carried out frequency division to produce the colour signal of composite video signal, and wherein phase shift angle is according to color and difference;

Luminance signal processor, being used to receive brightness data and changing this brightness data according to the 3rd control signal is analog luminance signal;

Regularly/and sync generator, be used to receive color control signal and clock signal, export first, second and the 3rd control signal and composite synchronizing signal, and be contained in brightness data in the colour signal to described luminance signal processor output packet; And

Mixer device is used for burst signal, colour signal, luminance signal and composite synchronizing signal are carried out mixing with the result of output as the mixing of composite video signal.

2. the composite video signal generator described in claim 1 is wherein had the frequency of burst signal frequency even-multiple by the clock signal that described oscillator produced.

3. the composite video signal generator described in claim 1, wherein said burst signal generator comprises one first filter, is used for the signal of conversion is carried out the sine wave of filtering with the output color subcarrier.

4. the composite video signal generator described in claim 3, and then comprise that second filter is used for the signal of phase shift and frequency division is carried out filtering.