JP2007298898A - Illumination optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact illumination optical system by shortening the entire length of a rod integrator in an illumination optical device. <P>SOLUTION: The illumination optical device is constituted of a light source 1, a condenser lens part 2 condensing emitted luminous flux from the light source, the rod integrator 3 guiding the condensed luminous flux, a relay lens part 4 for radiating the luminous flux emitted from the rod integrator 3, and a projection lens part 6 projecting an image formed from the radiated light by the relay lens part 4 to an image display means 7. A tapered part having an optional angle with an optical axis as center from the inside of the rod integrator 3 to the outer periphery part of an incident surface is formed on the rod integrator 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination optical apparatus using a rod integrator, and more particularly to a technique for irradiating an object with uniform light.

In a conventional illumination optical device, the light emitted from the light source is condensed on the rod integrator using a collimating lens, a dichroic prism, or a condenser lens, and the condensed light is emitted from the rod integrator and then relay lens And a projection lens unit. Among them, in order to make the rod integrator used to project the light uniformly without uneven illumination and to increase the brightness, the notch convex shape that can take in unnecessary outer peripheral light flux is formed at the entrance end and the exit. A technique for providing the edge is disclosed. (For example, refer to Patent Document 1.)
JP 2003-015220 A (page 7, FIG. 3)

  However, when a surface-emitting light source having a rectangular opening such as an LED or a semiconductor laser (hereinafter referred to as LD) is used, it can be focused in a spot shape that matches the rectangular opening size of the incident side of the rod integrator. However, the conventional configuration has a problem that unnecessary outer peripheral luminous flux is lost, so that the effect is lost, and sufficient uniformity of the emitted light from the rod integrator cannot be achieved.

  The present invention solves the above-described conventional problems. In the rod integrator, a rectangular spot emitted from a surface-emitting light source having a rectangular opening such as an LED or an LD and condensed in the rod integrator effective incident surface is provided. The object is to provide a compact illumination optical device that can make the illuminance unevenness of the illumination light emitted from the rod integrator uniform even when the total length is short, by increasing the number of reflections at.

  In order to solve the above-described conventional problems, an illumination optical apparatus according to the present invention includes a light source, a condensing lens unit that condenses the emitted light beam from the light source, a rod integrator that guides the collected light beam, and the rod integrator. A relay lens unit for irradiating a light beam emitted from the relay lens unit, and a projection lens unit for projecting an image generated from the irradiation light of the relay lens unit onto an image display means. A tapered portion having an arbitrary angle centered on the optical axis is formed from the end surface toward the outer peripheral portion of the incident surface.

  Further, in the illumination optical device, the light source is a surface emitting light source having a rectangular opening such as an LED or a semiconductor laser.

  Further, in the illumination optical apparatus, in the rod integrator, the maximum integration angle θ3 of the rod integrator is defined by the following formula 1 using the F number F of the projection lens unit and the imaging magnification M of the relay lens unit. It is.

  Further, in the illumination optical device, in the rod integrator, an angle θ1 formed by an arbitrary tapered portion and an optical axis is 80 degrees or more and less than 90 degrees.

  According to the illumination optical apparatus of the present invention, by increasing the total number of reflections in the rod integrator, the emitted light can be made uniform even when the rod integrator overall length is shortened, and the illumination optical unit can be made compact.

  Embodiments of an illumination optical apparatus according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a block diagram of an illumination optical device and a peripheral portion in the first embodiment of the present invention.
In FIG. 1, the light emitted from the surface emitting light source 1 is condensed on the rod integrator 3 by the condensing lens 2, propagated through the rod integrator 3 by multiple reflection, and then condensed by the relay lens 4 to create an image. The image is converted into an image by the unit 5 and projected onto a screen 7 as image display means by the projection lens 6. Here, the rod integrator 3 is provided with a tapered surface centered on the optical axis at the outer peripheral portion of the incident end surface, thereby increasing the number of reflections at the time of internal propagation and achieving uniform illumination unevenness with a shorter overall length.

Further, the rod integrator 3 will be described with reference to FIG.
As shown in FIG. 2A, the rod integrator 3 is a rectangular parallelepiped having a rectangular opening having an aspect ratio substantially equal to the screen 7 display ratio of 16: 9, and the irradiation light of the relay lens 4 is efficiently obtained. The maximum exit angle θ3 of the rod integrator 3 defined by Equation 1 obtained from the relationship between the F number of the projection lens 6 and the imaging magnification M of the relay lens 4 at the exit end of the rod integrator 3 so that the light can be condensed. 2 with respect to the incident angle θ2 of the rod integrator 3, a tapered portion 8 having an angle θ1 is provided on the outer peripheral portion of the incident end surface as shown in FIG. 2B from the incident end surface of the rod integrator rod integrator. .

  Further, the taper angle θ1, the maximum incident angle θ2, and the maximum emission angle θ3 of the rod integrator 3 are defined by the following equations.

  Therefore, for example, the maximum incident angle θ2 to the incident surface of the rod integrator 3 is 12 °, the refractive index n is 1.5, the F number of the projection lens 6 is 2.0, and the imaging magnification of the relay lens 4 is 1.0. In this case, the taper angle θ1 of the outer peripheral portion of the incident end surface of the rod integrator 3 for realizing the maximum emission angle θ3 (= 14.5 °) calculated by Equation 1 is about 86.5 ° from Equation 2.

  In this case, due to the tapered shape of the outer peripheral portion of the entrance surface of the rod integrator 3, the maximum light propagation angle θ4 in the rod integrator 3 is 80.4 °, compared to 82.1 ° in the non-tapered state. Therefore, the same number of reflections can be obtained even when the length of the rod integrator 3 without a taper is reduced to a maximum of 83%, and the illuminance unevenness can be made uniform.

  As described above, in the first embodiment, by providing the tapered surface with the optical axis as the center at the outer peripheral portion of the incident end surface of the rod integrator 3, the propagation angle of the light beam in the rod integrator 3 is changed and the same reflection is performed. The total length of the rod integrator 3 can be shortened even by the number of times, and the illumination optical device can be made compact.

  Also, by providing a diffraction grating (Fresnel shape is desirable) on the entrance surface of the rod integrator 3 of the first embodiment, the propagation angle of light in the rod integrator 3 can be changed, so that the number of multiple reflections is increased. Even with a short overall length, the illuminance unevenness can be made uniform.

  The illumination optical device according to the present invention can make the illuminance unevenness of the illumination light emitted from the rod integrator uniform even when the total length is short, and in particular, an image display device using a surface-emitting light source having a rectangular opening such as an LED or LD It is useful for such as.

The block diagram which described the illumination optical apparatus and peripheral part of this invention The figure which shows the shape of the rod integrator in Example 1 of this invention Detailed view explaining a conventional rod integrator

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface emitting light source 2 Condensing lens 3 Rod integrator 4 Relay lens 5 Image generation part 6 Projection lens 7 Screen 8 Taper part

Claims (4)

A condensing lens unit that condenses the light source and the light beam emitted from the light source;
A rod integrator that guides the collected light flux;
A relay lens unit for irradiating a light beam emitted from the rod integrator;
A projection lens unit that projects an image generated from the irradiation light of the relay lens unit onto an image display unit;
The rod integrator is formed with a taper portion having an arbitrary angle centered on the optical axis from the incident end surface of the rod integrator toward the outer peripheral portion of the incident surface.
An illumination optical device. The light source uses a surface emitting light source having a rectangular opening such as an LED or a semiconductor laser,
The illumination optical apparatus according to claim 1. 2. The illumination according to claim 1, wherein in the rod integrator, the maximum output angle θ3 of the rod integrator is defined by the following formula 1 using the F number F of the projection lens unit and the imaging magnification M of the relay lens unit. Optical device.

4. The illumination optical apparatus according to claim 3, wherein in the rod integrator, an angle θ <b> 1 formed by an arbitrary tapered portion and an optical axis is 80 degrees or more and less than 90 degrees.

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