TV Screen Sizing Considerations

or "The image is too big for the TV "

TV Basics

The image on a television screen is controlled by the electronics inside it. These circuits are designed to use the standard NTSC video signal that is sent to the TV by all video equipment including the AirLink system. The image might also be sent to the TV via an S-VHS (S-video) cable as from the Aitech scan converters.

The size of the image on a TV screen is not governed by the size of the TV. A two-inch TV will have the same image as a 200-inch TV. This is because the image is a function of the signal sent to it and the electronics in the TV.

You will notice that some of the image is not visible on your screen. The area that is missing is approximately one half inch around the edge of the full television screen. This is the result of a 1930's television technology called 'overscan'. Overscan has the affect of forming the TV image off the edge of the visible screen. Literally, the TV scan is continued past the viewable edge of the screen so that you can not see the edge of the image on the screen as you do on your computer monitor.

Part of fitting the computer image onto a TV comes from the fact that your monitor is rectangular while a TV is square. Aitech handles this issue with a square pixel that is sent to the TV.

Updating the Driver

Since the TV is controlled by its internal electronics we cannot change how it works and cannot stop the overscanning. We can, however, change the size of the picture that is sent to the TV. To use the scan converter you have set up your system for a desktop of 640x480. A TV uses 525 scan lines of which you see only about 480. If you install the software (version 4.1 or greater) you will find a new listing in your Start/Programs/ menu under Aitech Scan Converter. Within this folder you will find three items: Restore Display Driver, Uninstall (ver. 4.3 or greater) , and Update Display Driver. When you click on Update Display Driver you will change the screen (desktop) size to 600x440. This shortens both dimensions by 40 pixels to better fit the image on your TV screen.

"Driver not supported" Message

Since this (600x440) is a very nonstandard display size, some native drivers do not like it, and will not operate with this size. If this is the case you will get the error that tells you your driver is 'not currently supported' and to use the standard VGA driver. If you get this message you have two options. The first is to do nothing and use some of the suggestions below for dealing with the sizing of the screen if it is a problem for you. The second option is to do as suggested and change to the standard VGA video driver. NOTE: WRITE DOWN THE OLD SETTING FIRST BEFORE YOU MAKE ANY CHANGES TO YOUR SYSTEM.

Once you have changed to the standard VGA driver you will be limited to 16 colors. This is the main drawback of the VGA driver but it is always compatible with other software. Now you can follow the instructions above for updating the driver.

Resizing a window

Depending on your application, this size 'issue' may not be a problem for displaying the image on your computer. All programs that run in a standard Windows 'window' can be resized to fit your TV. This is done by minimizing the window (click the little 'square' button (middle one) in upper right corner of the screen. This shrinks the window to about one quarter of its size. Now you can move and resize it to fit your TV screen. Click on the title bar and drag it to the upper left corner of the TV. Now move the mouse pointer to the lower right corner of the window until you see a double-ended diagonal arrow - click and drag to lower right to fill the TV screen.

PowerPoint

If you are using PowerPoint the slight overscan may not be an issue but if it is you can make a slight adjustment when you build your slides. Leave a small area blank around the edge of your build screen when you make the slides. It has been reported that PowerPoint looks fairly bad in 16 colors so using the Standard VGA driver may not be an option for this application. You can also reset the size of the presentation. Click on File, then Page Setup, and set size of the page to 10x7 (default is 10x7.5). This will look like 'letter box' TV movie on your monitor but will look very good on the TV.

Laptops

If you are using a laptop, in most cases you will set up your application on the laptop then use the hot key combination (Fn+Fx - hold Fn key and press proper F1...F12 key) to witch to the TV presentation. With this scenario you need not be concerned with the Win95 desktop area on the TV. This has the added feature of your audience not having to watch all your startup and setup maneuvers - one switch and it is on the big TV for your audience.

Desktop Adjustments

There are several things you can do to bring the desktop into the TV screen. 

  1. Use the arrows on the TV OUT tab in Display Properties (only if you have installed the Screen Display Utility software mentioned above.  Note that this is older software and it is not compatible with all video cards in use today*) to shift the image down and to the right. 
  2. You can also raise the Windows Taskbar to come onto the TV screen. You do this by placing the mouse pointer on the top edge of the Taskbar (get the double arrow) and drag it up so you can see it on the TV. 
  3. You can also rearrange your icons to fit in the TV screen and then raise the task bar as above.

 

*Note: Our current (newer technology) scan converters resize the image automatically.  They do not use software and there is no need to adjust window size, taskbar size, or move any other elements of the screen.   Most people who are frustrated with the "sizing" aspect of our older technology scan converters will greatly appreciate using one of the newer products.  See the new scan converters here: http://aitech.com/products/converter.htm


Last update 9-20-2002