With the development of audio and video digital technology to the source DVD player is configured for the audio and video digital home theater, its clear picture of real shock, a wide range of surround sound, it is fascinating, is the next inevitable choice for home theater audio and video source . In appreciation of high-quality Dolby Digital surround sound, but also should be able to see colorful, crisp and clear, high-quality images. However, image quality is with the existing TV itself performance and the way the input signal has a close relationship. Whether by "playing Mount," so that ordinary high-definition TV can show the picture? Answer is yes. It is more sophisticated DVD player, in order to give full play to high-definition graphics, in addition is equipped with AV and S-VIDEO video output estuary, there is a group dedicated to high-resolution color display output interface component, that is Y, RY, BY signal output. This is the advanced video transmission. This article aims to talk about how to use the DVD player output color component signal to an ordinary TV picture quality is improved.

The basic color component signal is unprocessed original image signal. The most commonly used AV output video signals for transmission to facilitate the consideration, is the original R, G, B component signals through the code to be decoded from a complex process, the signal flow length, noise signals opportunities for mixed stacking, handling many links, hue shift error is easy to gradually accumulate, and the signal attenuation in the loss of high frequency components leaving the frequency characteristics easily deteriorate. There is poor resulting image is clear, color creeping, colored not allowed, such as color distortion and signal to noise ratio reduces the inherent problems. Regardless of how advanced the treatment means, not exactly the signal transmission without distortion processing, there will always be the signal distortion of demodulation errors. S-VIDEO (called S signal) is omitted, although the signal Y / C signal mixing, separation processes, so that the luminance signal from the impact of chroma trap circuit to improve image clarity, but the S signal is a semi-component signals, the C component or composite color signal, does not require U, V separate, synchronous demodulation, in order to restore the RY, BY color difference signals. Chroma signal C in the demodulation result of the process, there must be U, V separation is not complete, processing bit unbalanced distortion caused by hue, so S signal also crawl and color tone distortion. From TV to the present invention, it has been seeking to improve clarity, improve image quality, but nothing more than measures taken by the people in the circuit, the signal to compensate for the high frequency components in the upgrade and take various forms of so-called " Crochet "quality adjustment circuit. Through these measures to deal with images appear clear, but look there is ghosting the image noise increases, there is stiff not soft feel, so this image is not "original". Sustainability of this: In the TV has not yet fully before the arrival of the digital age, such as the analog video signal in order intact, without distortion transmission, we must shorten the signal transmission pathway, reducing the signal processing chain, try to use the original color component signal or color component signals, which but a key measure to achieve high quality. DVD player output color component signal is encoded in the synthesis of color inside the circuit across the output of the original signal directly, so this is the color component output enable high quality images the real reason.

As the TV home theater display terminals, in addition to a very small number of expensive large-screen flat screen color TV imports have color component signal interfaces, which are also made color TV sets have such Buceng Jian component interface. TV to further enhance image quality, you must have this color component interface, this interface is to solve the color component signals to the TV over the decoding circuitry inside the high-definition images can show the problem. To solve this interface problem, I plant developed HG-YUV01 TV color component signal input interface add-in board. Practice shows that this board scheme is feasible. Just look through the installation of comparison, the image quality real delicate.Significantly improved resolution, picture detail, contrast but no sense of rigid, structured, the transition soft, rich beautiful natural color, color accurate and pure tones, completely eliminating the AV output of the existence of the above series of questions, but also eliminates the so-called " Crochet "circuit brought a ghosting image blunt the feeling of really gives a refreshing visual satisfaction.

DVD machine and color TV color component signal to the interface

DVD color component signals and the TV interface, in essence, the color component signals in color television sets inside the matrix are added to recover the R, G, B color signals, then through the video amplifier circuits to drive the CRT display image. But in fact easier than one of the luminance signal Y and color TV interfaces, and how the interface of two color difference signals seem very easy, Moreover, various models used in TV decoder IC not the same. The interface can be fixed or consistent pattern to suit different types of color TV sets and different decoding the color component signal interface IC? We found that although a variety of color TV decoder IC used in the model, but they basically have a screen display interface (also known as graphic interface), this interface is typically used to display images with information such as teletext, picture in picture and external R, G, B image color component signals, but the most common is to use this interface to complete the output of the CPU OSD character signal.

According to the basic decoding IC with on-screen interface, all have this common ground, we have developed HG-YUV01 board, is the color component signals to the matrix on this board add processing to recover the R, G, B color signals, then decoded from the OSD interface into the IC. There sync signal interface issues can be found behind the above.

Input from the screen display interface, with a simple interface, strong adaptability and low technical difficulties, changes in the circuit less image quality, stable performance, the character on screen does not affect the original work of the advantages of the circuit.

Circuit theory and signal process

See Figure 1. DVD player output luminance signal Y, by foot from the CZ15 V1, V2, respectively, and inverting amplifier composed of an emitter follower, the last leg from the C3 coupled to the IC11. RY, BY color difference signal from the CZ13, 1 pin input, respectively, by R4C8, R6C11 coupled to the IC1 {15}, {12} feet. This three-component signal is added to IC1 operations within the matrix resulting R, G, B color signals, respectively, by IC17, 8,9 feet out.By the VD2 ~ VD5, VD6 ~ VD9 and R36 ~ R38 form four two input OR gate circuit. The IC1 output R, G, B signal and the output from the IC24 foot switch control signal to the VD2 ~ VD5 with positive, that is a four input OR gate. CPU on-screen character from the R, G, B color signal (B signal generally do not) and for screen display of the switch control signal (also called Y signal), the CZ3 through R40 ~ R43 to the positive VD6 ~ VD9 that the four input OR gate to another. This circuit design, or door form, the aim is: No matter what kind of TV is in working condition, the screen display character signal from the CPU should always be open.

Figure 1 CZ41 pin is used to control the work of the state TV to switch feet. When the CZ41, 2 feet open, which is a foot low, IC2 pin internal electronic switches SW25 ground, output 4-pin output low, VD5 end, CZ21 foot grounded due to R39, so that the OSD interface decoder IC Select the output pin is low, banned from the IC17, 8,9 feet out of the R, G, B signals into the manifold through the VD2 ~ VD4-screen interface. When a character needs to display when the screen display R, G, B CZ3 character signal will be passed through into the decoder IC VD7 ~ VD9-screen interface, and also with the character signal corresponding to the switch pulse (CPU chip called Y) signal is also passed CZ31 foot, feet out from the VD6 to the CZ21, real-time control decoder IC-screen interface select pin output high and low level, on-screen characters have different pixel position on the screen appears. When the CZ41, 2 feet shorter then, that is, its a foot high,, IC2 internal electronic switch flip switch SW2, then by 3 feet high, so its output by 4 feet high output VD5, by CZ21 feet into the decoder IC-screen interface to select the output pin, so high, the decoding IC internal selector switch will cut off its internal R, G, B signal output, so that IC1 output R, G, B signals into the decoder IC , through the internal clamp and then output to the video amplifier circuit, drive CRT displays the image color component signals.

How to solve synchronization problems

There are two options, see Figure 2. 1  CZ5 for the synchronous interface, when the CZ41, 2 feet open, the TV to work in TV or AV condition, the synchronous interface is the synchronous movement of the separation of BG-emitter circuit of this pathway off, change the board received the HG-YUV01 IC2 feet within the electronic switch SW12, SW1 has been constituted for IC2 in the closed-loop, and {15} feet by feet and back to the host by CZ52 core, into synchronous separation circuit TV in the TV or AV to complete the synchronization.When the CZ41, 2 feet shorter then, the TV to work into the color component input state, IC2 flip the switch SW1, the movement off the original board TV or AV video signal circuit, connected to the composition of the shot with the V5 control, the C19 color component signals sent by the brightness signal Y, but also by the IC2 {15} feet into the main circuit board by CZ52 feet in sync separator circuit, composite, component signal synchronization. 2  CZ5 interface, not altogether, do not change its related circuits. When the TV to play DVD images color component signals, the TV switches to AV working state, then DVD drive AV output video signal to TV AV terminal in the video interface, but also realize the synchronization problem.

How to install

Through the above and can be seen in Figure 2, the installation of this board is very simple to decode Manifold TA8659, 8759, and CPU Manifold M50436-560SP an example the installation method, the CPU block output to the decoding block TA8659 in the R, G , B and Y off the OSD character signal pathway, and then CPU of the R, G, B, Y CZ3 connected directly to the output pin, then off-screen interface, CZ2 and TA8659, respectively, each input pin can be connected directly, see Figure 2. Although some on-screen color TV decoder IC interface, but not being used, the OSD interface to the feet of the ground through the resistance and capacitance.Installation of this TV, the first leg will be on-screen interface, the resistance and capacitance to ground removed, then the installation can be, because CPU is another screen display character signal into the tube to go the other way, so this kind of remote control OSD circuit do not change, YUV01 board in the CZ3 can not accept empty. TV Host Core by the synchronous detection output and an external video signal sent by AV-side always only through an emitter-follower output to the color decoder, brightness and synchronization separation circuit. Select synchronous interface is to disconnect the video shoot with the separation circuit output and synchronization between the access road, cutting off both ends are connected to the CZ5, but note CZ51, 2 feet of wiring direction, see Figure 2. Power direct election machine 12V. CZ4 is the signal to switch control interface, DIP switches can be used to convert, of course, can be remote. Method is a way AV switch pin voltage is a direct quote received CZ41 can, in fact, this road has been changed to AV input color component signal input. YUV01 board VR1, VR2 to adjust the color component signals, respectively, image contrast and color saturation.

In the HG-YUV01 board basis, but also developed HG-YUV02 color component signal converter models. This converter is to Y, RY, BY converted to R, G, B color component signals and the H, V sync separation signals can also be composite sync output, mainly for the color component signal interface is not the projector, and other video equipment .