Display types: Difference between revisions

Revision as of 12:27, 1 March 2024

Backlit flat-panel displays

There are roughly two parts of such monitors you can care about: How the backlight works, and how the pixels work.

CCFL or LED backlight

https://nl.wikipedia.org/wiki/CCFL

LCD/TFT/similar

Self-lit

OLED

QLED

On image persistence / burn-in

VFD

larger segments
dot matrix VFD

Vacuum Fluorescent Displays are vacuum tubes applied in a specific way - see Lightbulb_notes#VFDs for more details.

Lighting

Nixie tubes

Mechanical

Mechanical counter

https://en.wikipedia.org/wiki/Mechanical_counter

Split-flap

https://en.wikipedia.org/wiki/Split-flap_display

LED segments

7-segment and others

✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

7-segment, 9-segment display, 14-segment, and 16-segment display. If meant for numbers will be a dot next to each (also common in general), if meant for time there will be a colon in one position.

These are really just separate lights that happen to be arranged in a useful shape.

Very typically LEDs (with a common cathode or anode), though similar ideas are sometimes implemented in other display types - notably the electromechanical one, also sometimes VFD.

Even the simplest, 7-segment LED involves a bunch of connectors so are

often driven multiplexed, so only one of them is on at a time.
often done via a controller that handles that multiplexing for you

Seven segments are the minimal and classical case, good enough to display numbers and so e.g. times, but not really for characters.

More-than-7-segment displays are preferred for that.

https://en.wikipedia.org/wiki/Seven-segment_display

DIY

LCD character dislays

Character displays are basically those with predefined (and occasionally rewritable) fonts.

Classical interface

The more barebones interface is often a 16 pin line with a pinout like

Ground

Vcc

Contrast

usually there's a (trim)pot from Vcc, or a resistor if it's fixed

RS: Register Select (character or instruction)

in instruction mode, it receives commands like 'clear display', 'move cursor',

in character mode,

RW: Read/Write

tied to ground is write, which is usually the only thing you do

ENable / clk (for writing)

8 data lines, but you can do most things over 4 of them

backlight Vcc
Backlight gnd

The minimal, write-only setup is:

tie RW to ground
connect RS, EN, D7, D6, D5, and D4 to digital outs

I2C and other

Matrix dislays

Small LCDs

These are sometimes incorrectly referred to OLED, which is a confusion with the small displays which are OLED (but usually monochrome).

Small OLEDs

@@ Line 51: / Line 51: @@
 ===OLED===
 <!--
-OLED are organic LEDs, which in itself is a just bit of practical production to production, but really just LEDs.
+OLED are organic LEDs, which in itself party just a practical production detail, but really just LEDs.
+(...though you can get fancy in the production process, e.g. see-through display may be OLED with substate trickery{{verify}})
-While OLED is also a thing in lighting, OLED ''very usually'' comes up in the context of OLED displays,
-a variant of monitors where the display pixels themself emits light, rather than a backlight, as it was in LED displays and CCFL displays (Most current displays are backlit with LED, not CCFL).
+While OLED is also a thing in lighting, OLED ''usually'' comes up in the context of OLED displays,
+a variant of monitors where the display pixels themself emits light,
+rather than a backlight (most monitors are still backlit, which previously were side-lit with CCFL, and now commonly side-lit with LED).
-One of the largest upsides of such monitors is that you can get a pixel that produces no no light, rather than a pixel that is blocking ''most'' of the backlight. As such, the blacks are blacker. There are some other details why they tend to look crisper.
+One of the largest upsides of such monitors is that you can get a pixel that produces no no light,
+in contrast with older screens that would block the backlight, but only ''mostly'' manage that.
+So the blacks are blacker. There are some other details why they tend to look crisper.
@@ Line 73: / Line 77: @@
-"Doesn't LED display mean OLED?"
+"Doesn't LED screen mean OLED?"
 No. "LED display" means LEDs were involved somehow. It can easily mean "we used a LED backlight instead of a CCFL" -- and the days, almost all LCD monitors are LED in this sense.
@@ Line 79: / Line 83: @@
 Marketing people ''really don't mind'' if you assume it's the same thing as OLED.
-You'll know when you have OLED, because it will have cost ''at least'' two thousand USD/EUR, more at TV sizes.
+You'll know when you have OLED, because it will cost ten times as much - two thousand USD/EUR, more at TV sizes.
 The cost-benefit for the non-rich isn't there.
@@ Line 98: / Line 102: @@
-It's brighter, but they're still working on some other details, like decent contrast.
+It's brighter, but they're still working on details like decent contrast.