H»ng sè ®iÖn m«i cña mét sè vËt liÖu
(cid:41)(cid:41) TiTiÖÖmm ccËËnn sisiªªuu ©©m (Ultrasonic proximity) m (Ultrasonic proximity)
(cid:38)(cid:38) LLμμ lolo¹¹i i cc¶¶mm biÕnbiÕn ssöö dôngdông bbéé thuthu phph¸¸tt tÝntÝn hihiÖÖuu sisiªªuu ©©m, m,
ttÇÇnn ssèè caocao..
a/ a/ §§ÆÆcc®®iiÓÓmm b/ b/ CC¸¸ccchÕchÕ®é®éhoho¹¹t t ®®ééngng c/ c/ ¶¶nhnhhh−ë−ëngngccññaamm««iitrtr−−êngêng
§§ÆÆcc®®iiÓÓmm
VVïïngngmmïï:: (cid:38)(cid:38) VVïïngng nnµµyy ttåånn tt¹¹i i ngay
ngay phÝaphÝa trtr−í−ícc cc¶¶mm biÕnbiÕn, , tutuúú theo
theo lolo¹¹i i cc¶¶mm biÕnbiÕn mmµµ 80 cm. NÕuNÕu ®®èèii tt−î−îngng ®−®−îîcc ®®ÆÆtt
vvïïngng mmïï nnµµyy cãcã khokho¶¶ngng cc¸¸chch chõng trong vvïïngng nnµµyy ssÏÏ khiÕn trong chõng 6 6 -- 80 cm. khiÕn chocho trtr¹¹ng ng thth¸¸ii ®®ÇÇuu rara khkh««ngng æænn ®®ÞnhÞnh..
song thiÕt 2 2 cc¶¶mm biÕnbiÕn cãcã ccïïngng khokho¶¶ngng cc¸¸chch cc¶¶mm nhnhËËnn ®−®−îîcc ®®ÆÆtt song nhau. . §§èèii tt−î−îngng ®®ÆÆtt vuvu««ngng gãcgãc vvííii ngunguåånn ©©m. m. VVËËyy khokho¶¶ngng qua khokho¶¶ngng cc¸¸chch cc¶¶mm
CC¸¸cccc¶¶mmbiÕnbiÕn®®ÆÆttsong song songsong:: (cid:38)(cid:38) GiGi¶¶ thiÕt song vvííii nhau song cc¸¸chch gigi÷÷aa cc¸¸cc cc¶¶mm biÕnbiÕn ®−®−îîcc xx¸¸cc ®®ÞnhÞnh thth««ngng qua nhnhËËnn..
(cid:38)(cid:38) VÝ VÝ dôdô nÕunÕu khokho¶¶ngng cc¸¸chch cc¶¶mm nhnhËËnn llµµ 6 cm, 6 cm, thth×× khokho¶¶ngng cc¸¸chch gigi÷÷aa cc¸¸cc
cc¶¶mm biÕnbiÕn llµµ 15 cm15 cm..
Kho¶ng c¸ch X (cm)
c¶m nhËn (cm)
6-30 20-130 40-300 60-600 80-1000
> 15 > 60 > 150 > 250 > 350
nhau, , chchïïmm phph¶¶nn xx¹¹ ccññaa
qua ththöö
NhiÔuNhiÔugiaogiaonhaunhaugigi÷÷aacc¸¸cccc¶¶mmbiÕnbiÕn (cid:38)(cid:38) NhiÔuNhiÔu xx¶¶yy rara khikhi cc¸¸cc cc¶¶mm biÕnbiÕn ®−®−îîcc ®®ÆÆtt ggÇÇnn nhau cc¶¶mm biÕnbiÕn nnµµyy ll¹¹i i tt¸¸cc ®®ééngng ®®ÕnÕn cc¶¶mm biÕnbiÕn khkh¸¸cc (cid:38)(cid:38) Trong Trong trtr−−êngêng hhîîpp nnµµyy khokho¶¶ngng cc¸¸chch X X ccÇÇnn ®−®−îîcc xx¸¸cc ®®ÞnhÞnh thth««ngng qua nghiÖÖmm.. nghi
thiÕt 2 2 cc¶¶mm biÕnbiÕn cãcã ccïïngng khokho¶¶ngng cc¸¸chch cc¶¶mm nhnhËËnn ®−®−îîcc ®®ÆÆtt ®®èèii didiÖÖnn
KhoKho¶¶ngngcc¸¸chchttèèiithithiÓÓuuchochohaihaicc¶¶mmbiÕnbiÕn®®ÆÆtt®®èèii nhaunhau (cid:38)(cid:38) GiGi¶¶ thiÕt nhau. . KhoKho¶¶ngng cc¸¸chch X X ®−®−îîcc xx¸¸cc ®®ÞnhÞnh saosao chocho 2 2 cc¶¶mm biÕnbiÕn khkh««ngng gg©©yy nhau nhau.. nhiÔu chocho nhau nhiÔu
Kho¶ng c¸ch X (cm)
c¶m nhËn (cm)
6-30 20-130 40-300 60-600 80-1000
> 120 > 400 > 1200 > 2500 > 4000
GãcGãcnghinghiªªngng:: (cid:38)(cid:38) GãcGãc nghi
truyÒn sãng
nghiªªngng gigi÷÷aa ®®èèii tt−î−îngng vvííii phph−¬−¬ngng truyÒn nghiªªngng ququ¸¸ llíínn sãng sãng phph¶¶ii ®−®−îîcc cc©©nn sãng phph¶¶nn xx¹¹ cãcã ththÓÓ khkh««ngng
nhnh¾¾c c khikhi ll¾¾p p ®®ÆÆtt. . NÕuNÕu gãcgãc nghi ®®ÕnÕn ®−®−îîcc cc¶¶mm biÕnbiÕn..
§§èèiivvííiichÊtchÊtlláángngvvμμvvËËttliliÖÖuudd−í−íiidd¹¹ng hng h¹¹t:t: (cid:38)(cid:38) §§èèii vvííii chÊt chÊt lláángng ((vÝvÝ dôdô nn−í−ícc) ) gigiííii hh¹¹n n gãcgãc nghi (cid:38)(cid:38) §§èèii vvííii vvËËtt liliÖÖuu dd−í−íii dd¹¹ng hng h¹¹t t thth×× gãcgãc nghi
nghiªªngng ëë 33oo nghiªªngng cãcã ththÓÓ llíínn ttííii 4545oo..
LoLo¹¹i i bbáá®®èèiitt−î−îngngnhiÔunhiÔu:: (cid:38)(cid:38) MMéétt ®®èèii tt−î−îngng nhiÔu
nhiÔu bÊtbÊt kk×× cãcã ththÓÓ nn»»mm trong trong phph¹¹m vi m vi cc¶¶mm nhnhËËnn ccññaa
nhiÔu ngng−−êiêi tata ddïïngng mméétt lolo¹¹i i vvËËtt liliÖÖuu cãcã khkh¶¶ nn¨¨ngng hÊphÊp thôthô
khiÕn chocho ngunguåånn ©©m m khkh««ngng ththÓÓ ttííii ®®èèii tt−î−îngng
cc¶¶mm biÕnbiÕn. . §§iÒuiÒu nnµµyy ssÏÏ gg©©yy rara tt¸¸cc ®®ééngng nhnhÇÇmm ccññaa cc¶¶mm biÕnbiÕn. . §§ÓÓ lolo¹¹i i bbáá ®®èèii tt−î−îngng nhiÔu ©©m, m, chchØØ ®Ó®Ó ll¹¹i i mméétt khekhe hhëë khiÕn nhiÔu ®−®−îîcc.. nhiÔu
§èi t−îng nhiÔu
Khe hë
VËt liÖu hÊp thô ©m
CC¸¸ccchÕchÕ®é®éhoho¹¹t t ®®ééngng::
KhuÕch tt¸¸nn
(cid:38)(cid:38) KhuÕch (cid:38)(cid:38) PhPh¶¶nn xx¹¹ (cid:38)(cid:38) XuyXuyªªnn susuèètt
KhuÕchKhuÕchtt¸¸nn:: (cid:38)(cid:38) §§©©y ly lµµ chÕchÕ ®é®é llµµmm viviÖÖcc phphææ biÕnbiÕn ccññaa cc¶¶mm biÕnbiÕn sisiªªuu ©©m. m. KhiKhi ®®èèii tt−î−îngng chuyÓÓnn trtr¹¹ng ng thth¸¸ii
Ph¹m vi c¶m nhËn
trong phph¹¹m vi m vi cc¶¶mm nhnhËËnn thth×× cc¶¶mm biÕnbiÕn ssÏÏ chuy bÞbÞ phph¸¸tt hihiÖÖnn trong ®®ÇÇuu rara, , chÕchÕ ®é®é nnµµyy hoho¹¹t t ®®ééngng nhnh−− mméétt cc¶¶mm biÕnbiÕn titiÖÖmm ccËËnn..
