Patent ID: 6188522
Filing Date: 2001-02-13
Classification: G02B

Abstract:
A projection lens for projecting light from a light source onto a screen to form a magnified image, comprising two joined lenses, each of which includes a negative lens and a positive lens, and satisfying the following requirements:(1) -0.04<ndI1-ndI2<-0.003(2) 13.9<vdI1-vdI2<31(3) -0.039<ndII1-ndII2<0.001(4) 0.8<vdII1-vdII2<11.5(5) -0.033<PgFII1-PgFII2<0.009where ndI1 represents a refractive index of the negative lens of the first joined lens;ndI2 represents a refractive index of the positive lens of the first joined lens;vdI1 represents an Abbe number of the negative lens of the first joined lens;vdI2 represents an Abbe number of the positive lens of the first joined lens;ndII1 represents a refractive index of the positive lens of the second joined lens;ndII2 represents a refractive index of the negative lens of the second joined lens;vdII1 represents an Abbe number of the positive lens of the second joined lens;vdII2 represents an Abbe number of the negative lens of the second joined lens;PgFII1 represents a partial dispersion ratio (ng-nF)/(nF-nC) with respect to a g-line and an F-line of the positive lens of the second joined lens; andPgFII2 represents a partial dispersion ratio (ng-nF)/(nF-nC) with respect to a g-line and an F-line of the negative lens of the second joined lens.