Purpose of “cups” inside headlight reflector

what is that thing in front of headlight bulb

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  • #1

wondering what is the exact purpose of the cups that partially shroud light bulbs in headlights?
the common answer i receive from friends is that the cups reflect light back to the reflector thus intensifying output. yet, when i examine (as best i can) the inside of the cups on my hyundai genesis high beams they seem to have no have a non-reflective surface.
i have seen these “cups” on high beams, but not on low beams in the same vehicle and vice-versa.
i have never seen such “cups” on aftermarket driving lights.
i am wondering if the purpose is to mute the intensity of lights?
i note that typical light bulbs have a light-obstructive cap at the end of the bulb. does this serve the same purpose as the “cups”?

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  • #2

they prevent direct viewing of the filament, and so minimize glare, especially if the bulb used (either by design or by modification) doesn’t have a coating on the tip of the bulb.

your friends are wrong: they do not intensify the beam.

  • #3

without the cups you would have a hotspot with corona and spill could be a distraction. with the cups, you just get even light across the beam, yet as mentioned at a diminished output.

  • #4

are you sure you’re not mistaking the beams? the dipped beam should have the cups to prevent glare from blinding other drivers. the main beams, which shouldn’t be used when other drivers are around so glare isn’t an issue, should be the lamps without the cups.

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  • #5

it is a bulb shield. it blocks unusable waste light that would otherwise cause glare (and backscatter in bad weather). this light cannot contribute usefully to the beam. removing the bulb shield does not (cannot) improve the headlamp’s performance in any way. keep your hands off it. smile and nod and ignore your ignorant friends.

  • #6

it is a bulb shield. it blocks unusable waste light that would otherwise cause glare (and backscatter in bad weather). this light cannot contribute usefully to the beam. removing the bulb shield does not (cannot) improve the headlamp’s performance in any way. keep your hands off it. smile and nod and ignore your ignorant friends.

absolute truth – the front cup blocks light that’s just headed out of the reflector, and isn’t any help where you need it (down the road) and would only blind drivers. maybe reflecting this half of the emitted light back into the reflector slightly increases light in the nearly-focused beam, but i’m unsure of that.

  • #7

maybe reflecting this half of the emitted light back into the reflector slightly increases light in the nearly-focused beam, but i’m unsure of that.

the bulb shield is not a reflector at all. its one and only
work is to block waste light.

  • #8

has there been any vehicles that didn’t have the cups? it seems like some vehicles have stupidly blinding factory headlights. atm, the only one i can think of is the jeep liberty. but there’s been many vehicles that i’ve seen that look like they don’t have them.

  • #9

in one of my cars i have the cups in my headlights, i think it strange because it have a h4 bulbs that already have a shield on them. on my other car there’s no cups and it also have h4 bulbs.

  • #10

has there been any vehicles that didn’t have the cups?

lots of them, yes. and they’re not “cups”, they’re bulb shields.

  • #11

stop calling them “cups”! they are “bulb shields”!

also, some of them would appear to be rings, such as in my ’95 previa. however, the headlights have fluted, rather than clear, lenses, which may have something to do with that design.

the bulbs themselves (9003/hb2) do have an anti-glare end cap (i’m not sure if all 9003/hb2 bulbs have that or not).

  • #12

re: stop calling them “cups”! they are “bulb shields”!

also, some of them would appear to be rings, such as in my ’95 previa. however, the headlights have fluted, rather than clear, lenses, which may have something to do with that design.

the bulbs themselves (9003/hb2) do have an anti-glare end cap (i’m not sure if all 9003/hb2 bulbs have that or not).

there are countless bulb shield designs. cups, rings, partial cylinders, upside-down shovels or scoops, plates, strips, boxes…

the blacked out end of the bulb is present on all 9003/hb2/h4, 9004/hb1, 9006/hb4, 9007/hb5, h7, h8, h11, and h13. without a bulb shield built into the lamp, the blackout tip can only do an adequate job of controlling stray light if the reflector is very deep and there’s no path stray light can take directly out of the lamp. even then you can get problems with stray light bouncing around inside the lamp and eventually exiting. it’s all according to packaging and optical design.

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Category: Headlights