Posts Tagged ‘ digital video camera monitors ’

LCD Video Camera Monitor

Wednesday, June 22nd, 2011

Most digital video security systems today are designed for use with an LCD video camera monitor.  There are a few reasons for this, but there are also reasons why it may be difficult to use an LCD monitor.  In the following article will discuss LCD monitors how they differ from CRT (Cathode Ray Tube) monitors and some of the advantages of using them instead of a CRT.

First of all, to understand the difference that exists between the two types of monitors let’s briefly discuss how each one works.  The CRT monitor receives an analog radio frequency signal that contains the information for drawing a picture on the front of the CRT or screen.   The CRT shoots horizontal beams of light back and forth from behind the screen very rapidly.  If your camera is a 500 TVL (TeleVision Line) camera and your CRT monitor screen is made up of 500 horizontal lines or more, then you’ll see every bit of the video image that is sent to the CRT in good detail.

In other words, the analog resolution measurement as it pertains to non-digital hardware is the TVL.  The higher the number the TVL the higher the resolution of the picture display.  A 500 TVL display means there are 500 horizontal lines (created by the ray of beams from the CRT).  This obviously will show less detail than say a 380 TVL of the same image.

Remember too that these lines can vary in size from monitor to monitor.  A 19 inch monitor will have much finer (thinner) lines than a 32 inch monitor.

Also, most analog screens have only two types of possible input/output connectors; a 75 ohm cable connector or an RCA plug.  These are a “standard” for analog video connections and are on the backs of most monitors and televisions.

A digital video security camera system Liquid Crystal Display or LCD video camera monitor differs from the CRT type in many ways.  First an LCD monitor is designed for digital input not analog.  This means there are different standards of measurement for the LCD monitor as compared to the CRT.

Another major difference is in the way the LCD video camera monitor displays its images.  Unlike the CRT whose picture consists of horizontal lines, the LCD monitor displays are in pixels.  Pixels are very small dots usually round or square in shape that make up the image and entire LCD screen viewing area.  Like the CRT’s horizontal lines being an indication of resolution or detail, the LCD’s standard for measurement is the pixel.  Keep in mind that pixels vary in size especially from small monitors to large monitors.

However, because these pixels on the average are much smaller than the TVL the LCD video camera monitor automatically makes for a good competitor to the CRT because of the enhanced capability to display a greater resolution or in other words, higher detail.

So the pixel is really the standard of measurement with an LCD video camera monitor.  This can be confusing as well because both resolution and size on an LCD video camera monitor are based on pixel measurements.  For example your monitor may have a screen that is 800 x 600 pixels.  Let’s re-emphasize that the 800 x 600 is the total amount of pixels available for displaying an image.

The image could be 340 x 280 pixels, so what does that tell us?  Basically it tells us the SIZE of the image–on your monitor or anyone else’s, the image will be 340 x 280 pixels.  (Remember that earlier we said pixel size can change with total screen size.)  The actual resolution or detail hasn’t been stated yet but generally speaking, the greatest resolution that can be obtained on an LCD Video Camera Monitor is 96 dpi or dots per inch.

So 96 dpi is actually the resolution.  Any image viewed on the monitor with a resolution greater than 96 would be wasting information.

To summarize then, a CRT monitor’s resolution is displayed as TVL or horizontal lines; the more the TVL the more detailed the picture.  High definition monitors and TV’s display 1080 TVL.  An LCD video camera monitor’s resolution is usually around 96 dots per inch.  The pixel measurement, such as 800 x 600 tells how big the image is but not what the resolution is.

So when shopping for an LCD video camera monitor be sure to keep these things in mind to make sure you get the type/size you need.


Camera Video Monitor

Tuesday, January 25th, 2011

A camera video monitor is used to view either the field of vision being captured by one camera or by a series of cameras in a digital video security system. Digital video camera monitors have made great strides in technological improvements in the last several years producing a higher quality, lighter, and more adaptive piece of digital video security system equipment.

It’s important to understand a little about the history of camera video monitors in security camera systems and how they used to work compared to how they work today. Let’s take a closer look at a camera video monitor.

First, we should identify the three main components of a video security system. That includes one to several video cameras, a video recorder, and at least one camera video monitor. Note that the word “digital” did not appear in the previous two sentences because we are referring to the older analog video security camera systems.

The older analog video camera systems consisted of analog video cameras which were basically miniature version of cameras used in an average television studio. However, since television cameras “broadcasted” their signal to the general public, security video cameras were often (and still maybe today) referred to as Closed Circuit Television or CCTV. The circuit is closed because the security system camera sends its signal to the video recorder and monitor, a closed circuit, rather than broadcasting it for unrestricted access.

The recorders used in these older analog systems were usually analog video tape recorders such as a VHS or BETA recorder and the monitors were basically miniature televisions. In contrast we use digital video security cameras, Digital Video Recorders or DVRs and high resolution camera video monitors with LCD, Plasma, or LED displays today.

The older “tube” type television camera video monitor and the analog video camera, worked with video in terms of “lines of resolution.” Without getting overly technical, the quality of these displays was much lower than today’s typical Plasma, LCD, or LED camera video monitor since the tube projected the image in alternating “lines.” Today the image is made up of pixels, extremely small dots or squares that can provide a much greater (or finer) resolution, and therefore a much higher quality display image.

Often times, older analog cameras would require an individual camera video monitor for each camera. Today however, depending on the size and resolution of the display, all of the cameras within a system can be displayed on one monitor. In fact, the digital video security systems used today do not require a camera video monitor to operate. A monitor is used to set the system up initially, but may be removed after the initial settings have been made. Yet, the monitor is still the component with the highest use since it is used to view live or recorded video in one way or another.

Of the three types of camera video monitors used today, the LCD is the most prevalent. Since video security systems have become digital, they have gained access to many of the technological improvements of personal computers. Therefore, monitors that are currently used for personal computing may also be used for digital video security systems with one provision; the monitor must have the capability to display using the output connectors for the system.

Personal computer monitors typically have VGA (Video Graphics Array), DVI (Digital Video Interface), or HDMI (High Definition Multimedia Interface) connectors for video input. Security digital video cameras however still utilize RG-59 coaxial cable with a BNC (Bayonet Neill-Concelman) connector. Most computer display monitors do not have BNC inputs; most security camera video monitors DO have BNC inputs.

This is important because if you choose to place a monitor on a single or specific camera, chances are it will need a BNC input connector. While most DVRs have BNC connectors for the camera inputs, they usually have several different output types to the monitor (VGA, DVI, and HDMI for example). When you purchase a camera video monitor for your security system, just make sure the outputs of the cameras and/or DVR matches the input connections of the monitor.

Security Camera King offers a wide variety of camera video monitors available for purchase. What’s more is that we also have BNC to VGA Monitor Converters available which allows you to view your video security camera with a BNC connector on a VGA monitor. In addition we also have monitor mounts available. For more information, talk to one of our security experts.