JP2558347B2 - Video signal synthesis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A video signal synthesizing method for synthesizing an image read out from a memory into a color video signal and transmitting the synthesized video signal. A video sync signal that originally generates a subcarrier and sync signal (SYNC) to generate a color video signal by reading the video signal from VRAM and combining it into a color video signal to improve the image quality. This display unit, a display timing generation unit that generates a timing signal for reading a serial video signal (digital) having multiple bits from VRAM based on the synchronization signal input from this video synchronization signal generation unit, and this display Sends a serial video signal (digital) with multiple bits according to the timing signal input from the timing generator. A VRAM to be output, and a video signal synthesizing unit for synthesizing a color video signal based on the video signal transmitted from this VRAM, the subcarrier signal input from the video synchronization signal generating unit, and the synchronization signal (SYNC). And is configured to send out a color video signal after being synthesized by the video signal synthesizing unit.

[Industrial applications]

The present invention relates to a video signal synthesizing method for synthesizing an image read out from a memory into a color video signal and transmitting the color video signal.

[Problems to be Solved by Conventional Techniques and Inventions]

Conventionally, when writing the screen to the memory with a personal computer etc., reading it out and converting it into a color video signal and displaying it on the display, the signal is taken out from the memory in synchronization with this using the clock etc. which the personal computer has It was converted into a video signal and displayed. Therefore, there is a problem that interlacing is not performed strictly and the image quality is deteriorated due to the phase difference between the subcarrier and the video signal.

The present invention is provided with a video sync signal generator, and reads a video signal from VRAM based on a sync signal and a subcarrier generated thereby to synthesize a color video signal,
The purpose is to improve image quality.

[Means for solving the problem]

 Means for solving the problems will be described with reference to FIG.

In FIG. 1, a video sync signal generator 1 generates a subcarrier and a sync signal (SYNC) for generating a color video signal.

The display timing generator 2 is the video synchronization signal generator 1.
A timing signal for reading a serial video signal (digital) having a plurality of bits from the VRAM3 is generated based on the synchronization signal input from the.

The VRAM 3 sends out a serial video signal (digital) having a plurality of bits according to the timing signal input from the display timing generator 2.

The DAC 4 converts a digital video signal into an analog video signal.

The video signal synthesizing unit 5 is based on the video signal (RGB) sent from the VRAM 3 and converted to analog by the DAC 4, and the subcarrier signal and the sync signal (SYNC) input from the video sync signal generating unit 1. It is for synthesizing color video signals.

[Action]

According to the present invention, as shown in FIG. 1, the display timing generation unit 2 inputs a timing signal to the VRAM 3 based on the synchronization signal (SYNC) input from the video synchronization signal generation unit 1 to generate a plurality of serial bits. The video signal with is input to the DAC4 and converted to an analog video signal (RGB), and the video signal combining unit is based on the video signal after this conversion, and the input synchronization signal (SYNC) and subcarrier signal. 5 is combined with a color video signal and output.

Therefore, by synthesizing the video signal read from the VRAM3 based on the sync signal into a color video signal by the sync signal and the sub-carrier, and outputting the color video signal,
It is possible to improve the image quality by performing interlacing on the video signal to be transmitted and accurately maintaining the phase between the subcarrier and the video signal.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be sequentially described in detail with reference to FIGS. 1 to 4.

In FIG. 1, a video synchronization signal generator 1 generates a subcarrier (3.58 MHz) and a synchronization signal (SYNC).

The display timing generator 2 receives the input sync signal (SY
NC) * RAS, * CAS, SAS, * ACK, * CD, * SFT
, Etc. to generate a timing signal (see FIG. 2,
(See FIG. 3).

The VRAM (video RAM) 3 is, for example, a dual-port RAM, in which data can be written in parallel from the CPU to the RAM section, and the data (for example, 32-bit width data) read from this RAM section can be written in 1 Color information 15
This is a video RAM having a structure for transmitting in bits (see FIGS. 2 and 3).

The DAC (DA converter) 4 converts a digital video signal into an analog video signal (RGB).

The video signal synthesizing unit 5 synthesizes a color video signal (NTCS video signal) based on the input video signal, subcarrier, and synchronization signal (SYNC).

Next, the configuration and operation of FIG. 1 will be sequentially described in detail with reference to FIGS. 2 to 4.

FIG. 2 shows a read configuration example of a video signal, and FIG. 3 shows a read explanatory diagram of the video signal. Here, the display timing generator 2, VRAM3, and DAC4 are the same as those shown in FIG.

In FIG. 2, the display timing generator 2 uses * RAS, * CAS, SAS (sum access strobe, S) based on the sync signal (SYNC) input from the video sync signal generator 1.
RAM3 that composes VRAM3)
-1 and ACK, * LD, and * SFT are input to the shift register 3-2 (see FIGS. 2 and 3 (a)).

RAM3-1 that composes VRAM3 corresponds to the * RAS, * CAS, and SAS inputs, and shifts the 32-bit data into the shift register 3-
3 is transferred (see FIG. 3 (A)). Here, as shown in FIG. 3B, the 32-bit data read from the RAM 3-1 and set in the SAM 3-2 is the SAS data.
In response to, the data is serially transferred to the shift register 3-3 via the SD (serial data bus) and set.

The shift register 3-3, which constitutes the VRAM3, divides the set 32 bits into two groups, and 15 bits of one 16 bits are converted into a video signal (digital,
It is sent to DAC4 as RGB 5 bits each.

DAC4 is the input 15-bit video signal (digital)
About the analog video signals (R, G,
B).

By the above operation, based on the timing signal input from the display timing generation unit 2, a digital video signal is read from the VRAM3 in pixel units and is converted into an analog video signal (R, G, B) by the DAC4. I am trying to do it.

FIG. 3A shows an operation waveform diagram of the configuration shown in FIG.
Figure (b) shows the structure of the dual port RAM.

 Next, FIG. 4 shows a video signal composition explanatory diagram.

In FIG. 4A, the subcarrier is a color signal subcarrier of 3.58 MHz.

The sync signal (SYNC, 15.75KHz) is a horizontal sync signal according to the NTSC system.

The video signal (RGB) is the video signal after being converted to analog by the DAC 4 in FIG.

The video signal is a signal synthesized based on the subcarrier, the synchronization signal (SYNC), and the video signal (RGB) as schematically shown in the drawing so as to conform to the NTSC standard.

FIG. 4B shows a subcarrier, a synchronization signal (SYNC),
2 schematically shows the operation of the video signal synthesizing unit 5 which receives the video signal and outputs the video signal.

Although the present embodiment has described the NTSC system,
The same may be applied to other methods such as L and SECAM.

〔The invention's effect〕

As described above, according to the present invention, a configuration is adopted in which the video signal read from the VRAM3 based on the sync signal is further combined into a color video signal by the sync signal (SYNC) and the subcarrier and output. Therefore, the video signal to be transmitted can be interlaced and the phase between the subcarrier and the video signal can be accurately maintained, and the image quality can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a configuration example of reading a video signal, FIG. 3 is an explanatory diagram of reading a video signal, and FIG.
The figure shows a video signal synthesis explanatory diagram. In the figure, 1 is a video synchronization signal generator, 2 is a display timing generator, 3 is a VRAM (video signal generator), 4 is a DAC, and 5 is a video signal synthesizer.

Claims (1)

(57) [Claims] 1. A video sync signal for generating a subcarrier for generating a color video signal and a sync signal (SYNC) in a video signal synthesizing method for synthesizing an image read out from a memory into a color video signal and sending it. The resolution of the screen for generating a serial video signal (digital) having multiple bits from the VRAM (3) based on the synchronization signal input from the generation unit (1) and the video synchronization signal generation unit (1). A display timing generating section (2) for generating a timing signal corresponding to an arbitrary display clock according to the like, and a serial video signal (digital signal having a plurality of bits by a timing signal input from the display timing generating section (2) ) Sending VRAM (3) and the digital video signal output from this VRAM (3),
A DAC (4) for converting into an analog video signal according to the timing signal, an analog video signal sent from the DAC (4), an analog video signal input from the video synchronization signal generating section (1), and the analog video signal. Video sync signal generator (1)
A video signal synthesizing unit (5) for synthesizing color video signals based on the subcarrier signal and the synchronization signal (SYNC) input from is provided, and the color after the video signal synthesizing unit (5) synthesizes A video signal synthesizing method characterized in that the video signal is transmitted.