Monitor performance difference

First, the difference between monitors and televisions

The monitor is functionally simpler than the television but in terms of performance, but it requires a higher demand than the television, and its main difference is reflected in three "degrees".

1. Image clarity

Since the traditional TV receives the RF signal transmitted by the TV station, the bandwidth of the video image corresponding to this signal is usually less than 6M. Therefore, the resolution of the TV is usually greater than 400 lines, which requires the monitor to have a high image resolution. A professional monitor should have a bandwidth compensation and boost circuit on the channel circuit as compared with a conventional television, so that the passband is wider and the image clarity is higher.

2. The degree of color reproduction

If the definition is mainly determined by the amplitude-frequency characteristics of the video channel, the degree of reduction mainly consists of the chrominance signals of the three primary colors red (R), green (G), and blue (B) and the phase of the luminance signal in the monitor. Decided. Since the monitor usually observes static images, the requirement for the color reproduction of the monitor is higher than that of the television. Therefore, the channel for the viewing channel of the professional monitor should have the brightness, color processing, and R, G, and B processing. Accurate compensation circuit and delay circuit to ensure phase synchronization of light/color signals and R, G, B signals.

3. Overall stability

When a monitor forms a closed-circuit monitoring system, it usually requires 24 hours a day, 365 days of continuous power-on use every year (while televisions usually only work a few hours per day), and some monitors may have a poor application environment. Requires higher reliability and stability of the monitor. Compared with televisions, in terms of design, the monitor's current, power consumption, temperature and resistance to electrical interference, the ability and margin of electric shock, and the average time between failures are much longer than those of TV sets. At the same time, the monitor must also The use of a fully shielded metal shell ensures electromagnetic compatibility and interference performance; in the selection of components, the characteristics of the components used in the monitor, such as voltage resistance, current, temperature, and humidity, are higher than those used in televisions; In the installation and debugging, especially the components and the aging process requirements, the monitor's requirements are also higher, the aging of the whole TV set is usually power on the assembly line at room temperature for about 8 hours, and the whole monitor Aging requires aging for more than 24 hours in the aging pipeline of a high-temperature, high-humidity, sealed environment to ensure the stability of the entire machine.

If you use a TV as a monitor for your surveillance system, apart from the fact that the image may be perceived as blurry (lower resolution and poorer color reproduction), the components used in the TV are not suitable for continuous use without interruption. If forced to use the TV as a monitor. If it is light, it is prone to malfunction. In severe cases, accidents may occur due to the high operating temperature of the television.

Second, the performance difference between CRT monitor and LCD monitor

Color monitors using cathode ray ray tubes (CRTs) and color monitors using liquid crystal displays (LCDs) are distinguished by the principle of image reproduction. The former uses magnetic deflection drives to implement line-field scanning (also called analog driving). Mode), while the latter uses a dot-matrix drive (also called a digital drive). Therefore, the former often uses television lines to define its sharpness, while the latter defines its resolution by the number of pixels. The clarity of a CRT monitor is mainly determined by the channel bandwidth of the monitor and the dot pitch and convergence error of the picture tube, while the latter is determined by the number of pixels of the LCD screen used. The CRT monitor has the advantages of low cost, high brightness, wide viewing angle, and long service life, while the LCD monitor has the advantages of small size (flat plate shape), light weight, no flashing, and no radiation of the image, but the LCD monitor The main disadvantages are high manufacturing cost, narrow viewing angle (darkened image when viewed from the side, reversed color when viewed from the side), and short service life (usually the brightness of the LCD screen is reduced to less than 60% of the normal brightness after 5000 hours of burning, but The average life span of CRT is up to 30,000 hours or more. It should be affirmed that price, perspective, and service life are the three bottlenecks that affect the popularity of LCD monitors. Of course, LCD is one of the most mature leading-edge products of flat panel display devices. It has been increasingly concerned by manufacturers at home and abroad, and its technology is continuously improving. In 2008, the LCD screen of the new TFT technology using in-plane switching technology has reached a 160° horizontal viewing angle and a vertical viewing angle of 140°; at the same time, the price of LCD screens will gradually increase with the product. As the popularity and production increase gradually and gradually decline, the service life of LCD will also increase with the progress of LCD backlight and liquid crystal material technology. It is entirely possible for LCD monitors to replace CRT monitors as mainstream products in the monitor market.