What is a horizontal sync signal (HSYNC)? – display term

Explanation of IT Terms

What is a Horizontal Sync Signal (HSYNC)? – A Display Term Explained

Have you ever wondered how your computer monitor or TV knows exactly when to draw each line of the image displayed on the screen? One of the key components responsible for this synchronization is the Horizontal Sync Signal (HSYNC).

The Role of HSYNC

HSYNC is a specific signal sent from a video source, such as a computer or DVD player, to a display device, indicating the beginning and end of each horizontal line of the image. It is a crucial part of the synchronization process that ensures the image is displayed correctly.

How HSYNC Works

When a video source sends an image to a display device, it splits the video signal into horizontal lines, and each line consists of a certain number of pixels. The HSYNC signal is then sent at the beginning of each line to mark the starting point of that line. This signal is followed by the video data representing the pixels of that line.

When the display device receives the HSYNC signal, it knows that the beginning of a new line is coming. It uses this signal to accurately position the electron beam (in a CRT display) or calculate the timing for drawing each pixel (in an LCD or LED display). This synchronization process ensures that each horizontal line is displayed correctly and results in a cohesive and properly aligned image on the screen.

Importance of HSYNC and Video Quality

Without HSYNC, the image would appear distorted, with lines misaligned or completely skewed. As the HSYNC signal precisely controls the timing for each horizontal line, it prevents visual artifacts such as horizontal tearing or rolling, which can occur when the display device is not properly synchronized.

Moreover, HSYNC is especially crucial in scenarios where interlaced video is used. Interlaced video, common in older CRT displays, divides each frame into two fields, displaying odd-numbered lines first and even-numbered lines next. The HSYNC signal ensures proper synchronization between these fields, resulting in a smooth, flicker-free image.

Conclusion

In summary, the Horizontal Sync Signal (HSYNC) plays a vital role in the synchronization of video signals displayed by a variety of devices. By precisely marking the beginning of each horizontal line, it enables displays to render images accurately, preventing visual distortions and ensuring a high-quality viewing experience.

Next time you watch a video or use a computer, remember the behind-the-scenes work of the Horizontal Sync Signal that allows you to enjoy a seamless and visually appealing display.

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