Optical: systems and elements – Lens – With support
Reexamination Certificate
2003-06-19
2004-12-07
Spector, David N. (Department: 2873)
Optical: systems and elements
Lens
With support
C359S819000
Reexamination Certificate
active
06829111
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a projection lens manufacturing apparatus, a projection lens manufacturing method, a projection lens manufactured by the projection lens manufacturing method and a projector having the projection lens.
2. Description of Related Art
A related art projector having a plurality of liquid crystal panels for respectively modulating a plurality of color lights in accordance with image information, a cross dichroic prism for combining the color lights modulated by the respective liquid crystal panels, and a projection lens for projecting the light beam combined by the prism in an enlarged manner to form a projection image has been used.
As a projection lens used for such a projector, a compound lens composed of a combination of a plurality of lenses including a converging lens and a diverging lens is used in order to minimize deterioration in resolution and spherical and color aberration. However, in order to have the lenses function correctly and obtain a high-quality projected image, the position of the optical axis (core) of respective lenses of the projection lens should be adjusted with high accuracy.
In the related art, after accurately processing the profile of the plurality of lenses and a lens-holding barrel that holds the lenses, a trial-and-error process was conducted for producing a high-quality projection lens, where a part of the components is exchanged until the optical axis is aligned by observing the projected image. However, since the variation of profile accuracy of the components dominates over the accuracy of optical axis alignment in such arrangement, the optical axis cannot be accurately adjusted and troublesome work is necessary for the trial-and-error production process.
Accordingly, an arrangement for a projection lens has been proposed, where holes for adjusting the lens position are provided on a lens-holding barrel on three locations at a regular interval on a plane orthogonal with the illuminating optical axis of the optical path formed inside the lens-holding barrel and a pin-member such as a screw directed from the outside to the center of the barrel is attached to the three position-adjusting holes. In such projection lens, the three pins are advanced and retracted to bias the lens to be adjusted so that the position of the lens is adjusted within the plane orthogonal with the illuminating optical axis.
Another arrangement has been proposed where the lens to be adjusted is clamped at a predetermined position and the lens-holding barrel accommodating the lens is moved to adjust the position of the lens. See Japanese Patent Laid-Open Publication No. Hei 8-334664.
Still another arrangement has been proposed where the lens is fixed by caulking inside the lens-holding barrel provided with a distortion absorber and, subsequently, the lens position is adjusted by moving the lens. See Japanese Patent Laid-Open Publication No. 2002-189159. The distortion generated by adjusting the lens is absorbed by the distortion absorber, whish is removed by beating.
In a further alternative related art arrangement, a lens-holding barrel for holding the lens is constructed of a first lens-holding barrel and a second lens-holding barrel provided on the outside of the first lens-holding barrel, and a lens-holding spring is disposed between the first lens-holding barrel and the second lens-holding barrel. The lens-holding spring is compressed by a screw provided on the second lens-holding barrel to adjust the first lens-holding barrel by moving in a direction orthogonal to the optical axis. See Japanese Patent Laid-Open Publication No. 2002-40308. In this arrangement, a holding ring is provided on the front end of the first lens-holding barrel and the first lens-holding barrel is sandwiched and fixed between the holding ring and the second lens-holding barrel.
However, in the related art method for adjusting the lens position where a pin is provided on the projection lens as a product itself, large number of components are required for constructing the projection lens, which results in high production cost and increase in size and weight of the projection lens.
In the related art arrangement where the in-plane position of the lens is adjusted to have directions, when one of the pins are advanced or retracted, the other two pins also have to be advanced or retracted, which makes it difficult to know how far the two pins have to be moved, in other words, to recognize the relationship between the advancement and retraction of the pins and the direction for the lens to be moved, thereby requiring complicated work for adjusting the optical axis. At this time, since the respective pins advance and retract in different directions, the opening area of the position-adjusting hole has to be set wide to some extent in accordance with the lens to be adjusted, which can result in deterioration in the quality of the projected image on account of light leakage through the opening.
According to the method disclosed in JP-8-334664, since a lens fixed to the lens-holding barrel is moved in accordance with the movement of the lens-holding barrel, the center of the fixed lens relative to adjustment light source is shifted. Accordingly, it can be difficult to align the optical axis of the fixed lens with the optical axis of the lens to be adjusted, thus being unable to adjust the optical axis position of the lens with high accuracy.
According to the method disclosed in JP-2002-189159, since the distortion absorber has to be provided on the lens-holding barrel, the size of the lens-holding barrel and, as a result, the projection lens having the lens-holding barrel is increased. Further, since the distortion generated on the distortion absorber is removed by heating, the lens cannot be made of plastics with low-heat resistance. Further, since the lens position fixed on the lens-holding barrel is adjusted against the holding force of the lens-holding barrel, fine-adjustment, i.e. adjusting the lens position with high-accuracy may become difficult.
According to the method disclosed in JP-2002-40308, since a position adjusting mechanism composed of lens-holding spring and screw is provided on the projection lens, the number of components of the projection lens is increased and the structure of the projection lens becomes complicated. Further, in order to provide such position-adjusting mechanism having such lens-holding spring and screw on the projection lens, the projection lens must be provided with two lens-holding barrels, i.e. the first lens-holding barrel and the second lens-holding barrel, which requires a holding ring provided on the front side of the first lens-holding barrel for fixing the first lens-holding barrel to the second lens-holding barrel, so that the size of the projection lens is increased in the optical axis direction.
SUMMARY OF THE INVENTION
The present invention provides a projection lens manufacturing apparatus and a projection lens manufacturing method capable of reducing the number of components to enable reduction in cost, size and weight of a projection lens, of easily adjusting the position of optical axis of a plurality of lens of the projection lens with high accuracy to obtain a high-quality image projection, and of easily manufacturing a projection lens without limiting the material to be used for the lens, a projection lens manufactured by the projection lens manufacturing method, and a projector having the projection lens.
A projection lens manufacturing apparatus according to an aspect of the present invention is for manufacturing a projection lens including a lens-holding barrel with a predetermined optical path being set inside thereof and a plurality of lenses sequentially arranged on an illuminating optical axis of the optical path, a pair of position-adjusting holes formed respectively on two axes orthogonal to each other to adjust the position of at least one of the plurality of lenses on a plane orthogonal to the illuminating optical axis along the two axes, the apparatus hav
Fujisawa Shohei
Okubo Hirotatsu
Umemura Shunji
Oliff & Berridg,e PLC
Seiko Epson Corporation
Spector David N.
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