JP2002357769A - Projection lens device and projector device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively compensate aberration by using a pair of aspherical lenses made of plastic in a projection lens device used for a projector device. SOLUTION: A 1A-th lens group and a 1B-th lens group are arranged on the front side of a diaphragm A, and a 2nd lens group is arranged on the rear side of the diaphragm A. Then, the aspherical lenses L2 and L11 for compensating the aberration are arranged second from the front side of the 1A-th lens group and at the rear end of the 2nd lens group. The lenses L2 and L11 are made of plastic, and the lens L2 on the front side is set to have negative power, and the lens L11 on the rear side is set to have positive power. When the lens made of plastic is deformed by heat and its refractive index is changed, influence thereby is negated by the lens having the positive power and the lens having the negative power, so that the deterioration of performance to compensate the aberration is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a front projection type projector device for projecting an image on a screen and a projection lens device used for the projector device.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 5-150158
JP, JP-A-5-150159, JP-A-6-16-195
As described in Japanese Patent Application Laid-Open No. 60708 or Japanese Patent Application Laid-Open No. 7-77652, there is known a projector device provided with a projection lens. That is, such a projector device includes a light source, a liquid crystal panel that modulates light emitted from the light source, and a projection lens that projects light modulated by the liquid crystal panel onto a screen.

In such a projection lens, a lens for correcting aberration is used. It is preferable to use an aspherical lens as the lens for aberration correction, and it is preferable to use a so-called plastic lens made of plastic in terms of ease of processing and manufacturing cost.

[0004]

However, in a projector device, each lens is heated by light or the like radiated from a light source. In particular, when a plastic lens is used, a change in the refractive index of a material due to heat or a change in lens shape is caused by heat. Due to the change, there is a problem that the performance of correcting the aberration is apt to decrease.

Japanese Patent Application Laid-Open No. 59-232314 discloses a configuration in which a liquid or gel-like medium layer is provided to compensate for a change in the focal length of a main lens made of plastic. No correction is shown.

An object of the present invention is to provide a projection lens device and a projector device that can effectively correct aberrations and reduce manufacturing costs.

[0007]

According to a first aspect of the present invention, there is provided a projection lens device comprising a first positive aspherical lens made of plastic and having a positive power having an aspherical lens surface for correcting an aberration, and a non-spherical lens for correcting an aberration. A second aspherical lens having a negative power and made of plastic having a spherical lens surface.

In this configuration, effective aberration correction can be performed using two aspherical lenses. In addition, the aspheric lens is made of plastic, so that the production becomes easy and the production cost is reduced. Further, since the two aspherical lenses form a pair of positive power and negative power, the effects of heat are canceled out, and the deterioration of aberration correction performance due to heat is suppressed.

According to a second aspect of the present invention, there is provided a projector device comprising: a light source; a modulating means for modulating light emitted from the light source;
The projection lens device according to claim 1 for projecting the light modulated by the modulation means.

[0010] In this configuration, since the projection lens device according to the first aspect is provided, it is possible to effectively correct aberrations, simplify manufacturing, and reduce manufacturing costs.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a projection lens device and a projector device according to the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a projection lens device, and the exit surface r23 of one dichroic cross prism 3 is arranged on the image forming side, that is, the rear side of the projection lens device 1. Furthermore, this dichroic cross prism 3
R (red), G (green), and B (blue) liquid crystal panels 4, which are display devices as modulation means, are arranged on the three incident surfaces r24. Further, a lamp as a light source is disposed behind these three liquid crystal panels 4 via a light source optical system (not shown).

That is, white light emitted from a lamp is separated into R (red), G (green), and B (blue) light by a dichroic mirror while being polarized by a light source optical system, and is converted into parallel light by each liquid crystal panel. 4 is incident. Then, the color light (corrected light source light) light-modulated according to the image signal when passing through each liquid crystal panel 4 enters the dichroic cross prism 3 from three incident surfaces r24, and the dichroic cross prisms 3 Outgoing surface r23 after color synthesis
From the projection lens device 1. Then, the image is enlarged and projected on the screen by the projection lens device 1.

The configuration of the projection lens device 1 is shown in FIG.
As shown in Table 1, there are eleven lenses L1 to L11, and these lenses L1 to L11 are a first lens L1, which is a negative meniscus lens having a convex surface facing the front side from the screen side, ie, the front side, and a convex surface facing the front side. Lens L as a second aspheric lens, which is a negative meniscus lens directed toward
2. Third negative meniscus lens with the convex surface facing the front
A lens L3, a fourth lens L4 that is a biconvex lens, a fifth lens L5 that is a biconcave lens, a sixth lens L6 that is a biconvex lens that is a correction lens, and a seventh lens L that is a biconcave lens
7, an eighth lens L8 which is a biconvex lens, a ninth lens L9 which is a biconvex lens, a tenth lens L10 which is a biconvex lens,
An eleventh lens L11 as a first aspheric lens, which is a positive meniscus lens having a convex surface facing the rear side. The fourth lens L4 and the fifth lens L5 are joined, and the seventh lens L7 having a strong negative power and the eighth lens L8 having a weak positive power are joined to form a cemented lens facing the diaphragm A. . Further, the second lens L2 and the eleventh lens L11 are plastic lenses, and the front surface r3 of the second lens L2
The rear surface r22 of the eleventh lens L11 is aspheric. On the other hand, the rear surface of the second lens L2 and the front surface of the eleventh lens L11 are spherical. A is aperture, r1
0 and r13 are virtual planes.

The first to third lenses L1 to L3 form a first A lens group forming a first lens group, and the fourth and fifth lenses L4 and L5 form a first lens group. 1B lens group is constituted, and the seventh to first lenses
A second lens group is constituted by one lens L7 to L11.

In Table 1, No. (r) is the lens surface including the virtual surface from the screen side, R is the radius of curvature, D is the distance to the next lens surface, Nd is the refractive index of the lens, and νd is the refractive index of the lens. This is the Abbe number of the lens. The table of aspherical surface (No. 3) is the aspherical surface on the front surface of the second lens L2, and the table of aspherical surface (No. 22) is the first aspherical surface.
The aspherical shape of the rear surface of one lens L11 is shown, K is a conical constant, and An is an nth order aspherical coefficient. In addition, the table at infinite object distance shows the maximum distance between r6 and r7, and r1
It shows the maximum distance between 0 and r11.

[0017]

[Table 1]

FIGS. 2A and 2B are longitudinal aberration diagrams of the first embodiment. FIG. 2A shows spherical aberration, FIG. 2B shows astigmatism, and FIG.
(c) is distortion. In the astigmatism, the broken line M is meridional, and the solid line S is sagittal.

According to the embodiment, the aberration is effectively corrected by using the two plastic negative and positive power aspheric lenses L2 and L11. it can.

That is, in general, a projector device
Each lens has heat due to the correction light source beam. This heat may cause the lens to be thermally deformed, reduce the refractive index of the lens material, and reduce the performance of the lens. In particular, plastic lenses are easily deformed by heat. On the other hand, an aspheric lens is suitable as a lens for aberration correction, and a plastic lens is preferably used in terms of manufacturing cost, easiness of processing, and the like.
However, the adoption of a plastic lens tends to be accompanied by a decrease in lens performance due to thermal deformation.

Therefore, in the present embodiment, the plastic lens for aberration correction is made up of a positive power lens (eleventh lens L11) and a negative power lens (second lens L2) whose effects due to thermal deformation are opposite to each other. With this configuration, it is possible to suppress a decrease in lens performance due to heat while reducing manufacturing costs.

The second lens L2 located on the front side is
The coma aberration is mainly corrected, and the eleventh lens L11 located on the rear side mainly corrects the image plane aberration.

If each lens has a constant thickness, uneven deformation due to heat can be suppressed, but if the thickness is uniform, it becomes difficult to sufficiently correct aberrations. Therefore, the lens has different thickness dimensions between the central portion and the peripheral portion within a range necessary for aberration correction, and furthermore, has a different thickness between the central portion and the peripheral portion during heating. The shape of the central part and the peripheral part of the lens is adjusted so as to suppress uneven deformation.

Further, by making the positive power lens and the negative power lens substantially similar in shape, the influence of heat can be easily and effectively canceled, and the aberration correction performance can be secured.

[0025]

According to the first aspect of the present invention, a first positive aspherical lens made of plastic and having a positive power and having an aspherical lens surface for correcting aberrations, and an aspherical surface for correcting aberrations are provided. Since a second aspherical lens made of plastic having a lens surface and having negative power is provided, aberration can be effectively corrected using two aspherical lenses. Further, the aspherical lens is made of plastic, so that the manufacturing can be facilitated and the manufacturing cost can be reduced. Further, since the two aspherical lenses form a pair of positive power and negative power, the influence of heat can be canceled out, and the deterioration of aberration correction performance due to heat can be suppressed.

According to the projector device of the second aspect, since the projection lens device of the first aspect is provided, the aberration can be effectively corrected, and the production becomes easy, and the production cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a projection lens device of the present invention.

FIG. 2 is an aberration diagram of the projection lens device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection lens device 4 Liquid crystal panel as a modulating means L2 Second lens as a second aspherical lens L11 Eleventh lens as a first aspherical lens r3, r22 Aspherical surface

Claims (2)

[Claims] 1. A first positive aspherical lens made of plastic having an aspherical lens surface for correcting aberrations, and a first aspherical lens made of plastic having an aspherical lens surface for correcting aberrations. A projection lens device, comprising: two aspheric lenses. 2. A light source, a modulating means for modulating light emitted from the light source, and a projection lens device according to claim 1, which projects the light modulated by the modulating means. Projector device.