Research about telecentric lens

Board in the electronic component to mounting in the step of, each electronic component position exactly positioning to fit, the suction nozzle in the suction images of electronic components recognizing camera in imaging, and the resulting image data By finely adjusting the position of the suction nozzle by performing arithmetic processing, even a slight misalignment of the electronic component is corrected. Used in the recognizing camera lens as is the object upon recognizing (electronic components), the object is an optical axis be moved (variation) in the direction taken image so as not to size changes, the object-side telecentricity Need to be raised.

Thus, conventional with telecentricity on the object side telecentric lens is generally of three parts (a), (b), (c),

it has arrived from (i) the object telecentric a light fetches the aperture stop towards the bending first order to the lens group,

(b) an aperture stop various are arranged before and after the aberration second lens group for correcting,

(c) the subject light to a predetermined position of the image plane formation It is

composed of a third lens group for making an image (for example, Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4).

In these lens groups, the first lens arranged closest to the subject (object) in the first lens group is required to have a lens diameter equal to or larger than the size of the subject. Further, lenses other than the first lens also need to have the same lens diameter, and particularly in the case of reduced photography, the lens diameter is significantly larger than that of the second lens group and the third lens group.

Overview

Reduce the cost of the lens applied to the recognition camera of the mounting machine . Positive refractive power having a biconvex first lens 1, having a positive refractive power with a convex surface facing the object side plano-convex second lens 2, the third biconvex lens having a positive refractive power 3. Joined to the third lens 3 with a biconcave fourth lens 4, an aperture 9, and a biconcave fifth lens 5 with a negative refractive force, and a fifth lens 5. A biconvex sixth lens 6 with positive refractive power, a biconvex seventh lens 7 with positive refractive power, and a meniscus-shaped eighth lens with positive refractive power with the convex surface facing the object side . The lenses 8 are arranged in order from the object side to the image plane side. As a result, a lens having telecentricity on the object side, which is inexpensive as a whole, can be obtained.

Purpose

The present invention has been made in view of the above circumstances, and an object of the present invention is to have an imaging range of about φ60 mm and an imaging magnification of about × 0.4 while satisfactorily correcting various aberrations. conjugate length is suppressed to less suitable length 240 mm, Kos attained a reduction of bets, it is to provide a telecentric lens having a telecentricity on the object side.

Claim 1

A biconvex first lens having a positive refractive force with a convex surface facing the object side and the image plane side in order from the object side to the image plane side, and a convex surface facing the object side and a plane facing the image plane side. A plano-convex second lens with positive refractive power, a biconvex third lens with positive refractive power with convex surfaces facing the object side and image plane side, and concave surfaces on the object side and image plane side. A biconcave fourth lens with a negative refractive force joined to the third lens, an aperture aperture with a predetermined diameter, and a negative refractive force with the concave surface facing the object side and the image plane side. A biconcave fifth lens having a biconvex shape, a biconvex sixth lens having a positive refractive force joined to the fifth lens with a convex surface facing the object side and the image plane side, and an object side and an image plane side. It has a biconvex seventh lens having a positive refractive force with a convex surface facing the surface, and a meniscus-shaped eighth lens having a positive refractive force with a convex surface facing the object side and a concave surface facing the image plane side . A telecentric lens that features that .

Claim 2

The telecentric lens according to claim 1, wherein when the refractive index of the first lens is N1 and the refractive index of the second lens is N2, the following conditional equations (1) and (2) are satisfied. .. (1) 1.60 <N1 <1.65 (2) 1.60 <N2 <1.65

Claim 3

The telecentric lens according to claim 1 or 2, wherein the first lens and the second lens are made of the same glass material .

Claim 4

The telecentric lens according to any one of claims 1 to 3, wherein the third lens and the seventh lens are made of the same glass material.

Claim 5

The telecentric lens according to any one of claims 1 to 4, wherein the fourth lens, the fifth lens, and the eighth lens are made of the same glass material.

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