Cathode ray tubes (CRT) are analog addressing displays because you can light a point on its surface applying a continuous electric or magnetic field to deflect electrons beam. Virtually, there is no limit on the resolution that CRT can reach. On the other hand, TFT-LCD, for example, are digital displays because you can only light discrete points of its surface. Moreover, you are limited to a fixed set of points, so resolution is limited and fixed.

Are there any technologies (old and new) that allows an analog addressing of a flat panel display with no fixed resolution? For example, a thin film of electroluminescent material between two continuous (versus discrete addressing lines in common displays) electrodes that allows addressing any point of its surface with analog signal without the need of an intermediate analog-digital conversion.


1 Answer 1


There are too many wrong assumptions in your question.

No, there are certainly theoretical limits on the resolution CRTs can reach. The electron beam is never a perfect point when it hits the screen. At the lowest level, electrons are probability functions. However, well above that, you can't get them to line up perfectly in a straight line, even at the macro level. Then the phosphor has some thickness, and will bleed out the spot on its own a little too.

You mention that TFT-LCD displays have pre-determined finite pixels. That is true. However, this is a pointless off-topic comment since you then ask about flat panel displays.

CRTs can and have been made flat, so that's one example of analog addressable flat panel displays. There are also displays made by deflecting thin laser beams with mirrors, which take analog deflection signals at their lowest levels.

Of course any discrete display can be wrapped with circuitry to take analog signals as inputs. This is done routinely by LCD monitors that plug into a SVGA output of a computer. SVGA carries analog signals, yet the LCD monitors are inherently discrete, at least in position. By converting a analog signal to digital, you can drive a discrete output device with a analog signal.

Modern computer displays are driven from interfaces, like HDMI for example, that are digital to avoid this extra conversion step. That is more efficient, less prone to noise, and eliminates the need to try to sync up to the pixel clock (since the pixel clock is provided directly).

  • $\begingroup$ Yes, I mentioned many wrong assumptions in favor of brevity. I will edit my question to be more correct. $\endgroup$ Oct 12, 2015 at 13:56

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