Is there such a thing? All I can find on the net are smallish alphanumeric and graphical displays. Thanks, Viktor
Large 7-segment OLED
Started by ●December 2, 2006
Reply by ●December 3, 20062006-12-03
On 2 Dec 2006 10:07:55 -0800, "Viktor" <vkesler@gmail.com> wrote:>Is there such a thing? >All I can find on the net are smallish alphanumeric and graphical >displays. > >Thanks, > >ViktorWhy OLED instead of conventional LED?
Reply by ●December 3, 20062006-12-03
On Dec 3, 2:00 pm, Mike Harrison <m...@whitewing.co.uk> wrote:> On 2 Dec 2006 10:07:55 -0800, "Viktor" <vkes...@gmail.com> wrote: > > >Is there such a thing? > >All I can find on the net are smallish alphanumeric and graphical > >displays. > > >Thanks, > > Viktor >>Why OLED instead of conventional LED?Power consumption.>From what I've seen in the alphanumeric OLED datasheets, you get decentvisibility without backlighting. I was hoping to find single or several digit displays to make a large clock module with only a few W consumption. I don't know if it's just a matter of time before these appear or if there's a technology constraint in making large OLED segments. Viktor
Reply by ●December 3, 20062006-12-03
Viktor wrote:> On Dec 3, 2:00 pm, Mike Harrison <m...@whitewing.co.uk> wrote: > > On 2 Dec 2006 10:07:55 -0800, "Viktor" <vkes...@gmail.com> wrote: > > > > >Is there such a thing? > > >All I can find on the net are smallish alphanumeric and graphical > > >displays. > > > > >Thanks, > > > > Viktor > >>Why OLED instead of conventional LED? > > Power consumption. > > From what I've seen in the alphanumeric OLED datasheets, you get decent > visibility without backlighting. I was hoping to find single or several > digit displays to make a large clock module with only a few W > consumption. > > I don't know if it's just a matter of time before these appear or if > there's a technology constraint in making large OLED segments.>From what I've read, current OLEDs have lower efficiency thanconventional LEDs, so at the same brightness, a conventional LED should have lower power.
Reply by ●December 3, 20062006-12-03
Viktor wrote:> > On Dec 3, 2:00 pm, Mike Harrison <m...@whitewing.co.uk> wrote: > >>On 2 Dec 2006 10:07:55 -0800, "Viktor" <vkes...@gmail.com> wrote: >> >> >>>Is there such a thing? >>>All I can find on the net are smallish alphanumeric and graphical >>>displays. >> >>>Thanks, >> >>Viktor >> >>>Why OLED instead of conventional LED? > > > Power consumption. > >>From what I've seen in the alphanumeric OLED datasheets, you get decent > visibility without backlighting. I was hoping to find single or several > digit displays to make a large clock module with only a few W > consumption. > > I don't know if it's just a matter of time before these appear or if > there's a technology constraint in making large OLED segments.It's more likely simple economics - the market for jumbo LEDs is relatively tiny, (and primitive) and anyone developing OLED displays will chase the larger revenue streams first. How large a display are you after, on what power budget ? -jg
Reply by ●December 4, 20062006-12-04
On 3 Dec 2006 07:58:44 -0800, "Viktor" <vkesler@gmail.com> wrote:> > >On Dec 3, 2:00 pm, Mike Harrison <m...@whitewing.co.uk> wrote: >> On 2 Dec 2006 10:07:55 -0800, "Viktor" <vkes...@gmail.com> wrote: >> >> >Is there such a thing? >> >All I can find on the net are smallish alphanumeric and graphical >> >displays. >> >> >Thanks, >> >> Viktor >>>Why OLED instead of conventional LED? > >Power consumption.Are OLEDs actually any more efficient than standard LEDs for the same light output? I suspect probably not. OLEDs typically compete with LCDs, which throw away at least 50% of th backlight light in the polariser, and then about 60% mode in the RGB filters. Not hard to compete with that with a light-emitting product.>>From what I've seen in the alphanumeric OLED datasheets, you get decent >visibility without backlighting. I was hoping to find single or several >digit displays to make a large clock module with only a few W >consumption.A few W will run a bunch of (carefully chosen) normal LEDs pretty darn bright. And it will last longer - OLEDs still have some lifetime issues ISTR.
Reply by ●December 4, 20062006-12-04
On Dec 3, 7:46 pm, Jim Granville <no.s...@designtools.maps.co.nz> wrote:> > How large a display are you after, on what power budget ? > > -jgThanks for the answers everybody. I must admit, I've never actually seen a real live OLED so all my information is hazy at best. I imagined it to be something like an LCD with its own light source. So, I thought that in bright light it would have a reflective component like LCDs (I've worked with some big LCDs for petrol station pump displays and they are very good at high ambient light.) The largest 7-segment LED display I found (LITEON) had a 76mm digit height and was stated at 30mcd/20mA. With four digits, and about 20 segments, that would be about 5W. I can just about manage that, but it wouldn't be at its brightest and it would probably be poor in daylight. So, is it just wishful thinking or do OLEDs have a reflecive function like LCDs? Viktor
Reply by ●December 4, 20062006-12-04
Viktor wrote:> On Dec 3, 7:46 pm, Jim Granville <no.s...@designtools.maps.co.nz> > wrote: > > > > > How large a display are you after, on what power budget ? > > > > -jg > > Thanks for the answers everybody. > I must admit, I've never actually seen a real live OLED so all my > information is hazy at best. I imagined it to be something like an LCD > with its own light source. So, I thought that in bright light it would > have a reflective component like LCDs (I've worked with some big LCDs > for petrol station pump displays and they are very good at high ambient > light.) > > The largest 7-segment LED display I found (LITEON) had a 76mm digit > height and was stated at 30mcd/20mA. > With four digits, and about 20 segments, that would be about 5W. I can > just about manage that, but it wouldn't be at its brightest and it > would probably be poor in daylight.5W for 20 segments @ 20mA doesn't sound right. At 1 Volt forward voltage, the power is 20mW/segment, or 400 mW total. I don't know the LITEON specs, but even if Vf is somewhat higher, you don't get close to 5 W. Of course, if you add in the dissipation in the series resistor, total power will be higher, but you can reduce that by using a lower drive voltage made from a switching power supply (use a SimpleSwitcher for instance), in combination with a smaller resistor. If you multiplex the displays, you can use a higher peak current, so the resistor can be even smaller, resulting in lower losses.
Reply by ●December 4, 20062006-12-04
On Dec 4, 7:40 pm, "Arlet" <usene...@ladybug.xs4all.nl> wrote:>.5W for 20 segments @ 20mA doesn't sound right. At 1 Volt forward > voltage, the power is 20mW/segment, or 400 mW total. I don't know the > LITEON specs, but even if Vf is somewhat higher, you don't get close to > 5 W. > > Of course, if you add in the dissipation in the series resistor, total > power will be higher, but you can reduce that by using a lower drive > voltage made from a switching power supply (use a SimpleSwitcher for > instance), in combination with a smaller resistor. > > If you multiplex the displays, you can use a higher peak current, so > the resistor can be even smaller, resulting in lower losses.Six LEDs in series for each segment. The chart gives 20mA If @ 12V Vf.
Reply by ●December 4, 20062006-12-04
Viktor wrote:> On Dec 4, 7:40 pm, "Arlet" <usene...@ladybug.xs4all.nl> wrote: > >.5W for 20 segments @ 20mA doesn't sound right. At 1 Volt forward > > voltage, the power is 20mW/segment, or 400 mW total. I don't know the > > LITEON specs, but even if Vf is somewhat higher, you don't get close to > > 5 W. > > > > Of course, if you add in the dissipation in the series resistor, total > > power will be higher, but you can reduce that by using a lower drive > > voltage made from a switching power supply (use a SimpleSwitcher for > > instance), in combination with a smaller resistor. > > > > If you multiplex the displays, you can use a higher peak current, so > > the resistor can be even smaller, resulting in lower losses. > > Six LEDs in series for each segment. The chart gives 20mA If @ 12V Vf.Ah, I see.. that makes sense. However, at 30mcd/20mA, these aren't the most efficient. There are single LEDs that are a few thousand mcd, at lower power. Perhaps you can make your own display by taking some state of the art LEDs, and mount them behind some diffusing plastic yourself ?
