JP2006317611A - Illuminating optical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminating optical apparatus efficiently composing and outputting light from a plurality of light sources without performing light shielding causing heat generation and the change of polarization. <P>SOLUTION: A condenser lens 130 condenses a main illuminating light from a main light source 110 and a sub illuminating light from a sub light source 120 on a common focus. A rod integrator 150 is a means for adding and homogenizing the main illuminating light and the sub illuminating light supplied to the focus in such a way, and is fixed while its incident surface is positioned on the focus of the condenser lens 130. The main illuminating light and the sub illuminating light made incident on the rod integrator 150 are propagated to an emitting surface while they are reflected on the inner wall surface of the rod integrator 150. In the process of such propagation, the main illuminating light and the sub illuminating light are stirred, become the homogenized light and are output from the emitting surface of the rod integrator 150. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination optical apparatus suitable as a light source for an image display apparatus such as a projector (projection apparatus).

  A projector that is an image display device divides illumination light emitted from a light source into red, blue, and green wavelength bands and modulates them with a spatial modulation element such as a liquid crystal display panel. After being synthesized by the synthesis optical system, it is projected on a screen to form a color display image. As a light source for such a projector, there is an ultra-high pressure mercury lamp with high luminous efficiency in the visible light wavelength band. However, the ultra-high pressure mercury lamp can secure a sufficient amount of light in the wavelength band near 440 [nm], which is the blue and green wavelength band, while the red wavelength band is in the wavelength band near 550 [nm]. In the wavelength band of 600 [nm] or more, a sufficient amount of light cannot be ensured as compared with the blue and green wavelength bands. For this reason, conventionally, in order to keep the chromaticity at the time of white display close to an appropriate value, measures have been taken to reduce the amount of light in the blue and green wavelength bands in accordance with the weak red wavelength band. This is because if the amount of light in the blue and green wavelength bands is not reduced, what should be displayed in white becomes greenish white. However, when such measures are taken, for example, when considering D65 (chromaticity that is generally regarded as a white reference) as a reference, the amount of light in the entire wavelength band is adjusted to the red wavelength band with low intensity. Therefore, it is inevitable that the display screen becomes dark. In addition, there is a problem that part of the illumination light emitted from the light source is wasted.

  Patent Document 1 discloses an illumination optical device shown in FIG. 4 in order to solve such a problem. This illumination optical device has a main light source 6 using an ultra-high pressure mercury lamp 5 and a sub-light source 8 using a laser light source using a semiconductor laser 7. Here, the main light source 6 reflects the illumination light of substantially white light emitted from the ultrahigh pressure mercury lamp 5 directly or by the reflector 9 and outputs it to the fly-eye lenses 10A and 10B. The fly-eye lenses 10A and 10B emit the main illumination light from the main light source with a uniform light amount distribution. The subsequent polarization conversion element 12 converts the P-polarized component into the S-polarized component and transmits the light emitted from the fly-eye lenses 10A and 10B. The condenser lens 13 converts the light emitted from the polarization conversion element 12 into a substantially parallel light and emits it. As a result, the main light source 6 emits main illumination light from the ultrahigh pressure mercury lamp 5 with a substantially uniform light amount distribution and with substantially parallel light rays. In contrast, the sub-light source 8 emits a laser beam having a wavelength of about 650 [nm], which is a red wavelength band, from the semiconductor laser 7. The sub-light source 8 is disposed so that the optical axis of the laser beam is substantially orthogonal to the optical path of the main illumination light, corrects the light beam shape of the laser beam via a predetermined optical system 14, and also distributes the light amount. Correct the divergence angle. Note that the tilt of the semiconductor laser 7 is set so that the sub light source 8 has a polarization plane corresponding to the polarization plane of the main illumination light.

A reflection hologram element 17 is disposed at a position where the optical paths of the main and sub illumination lights intersect with each other so as to be inclined at an angle of approximately 45 degrees with respect to the optical paths of the main and sub illumination lights. Here, the reflection hologram element 17 is a so-called thick Lippmann hologram, and reflects the secondary illumination light in the direction of the arrow X by selecting the diffraction wavelength band, and excludes the wavelength band corresponding to the secondary illumination light. Thus, the main illumination light is transmitted and output in the arrow X direction. The reflection type hologram element 17 replaces the insufficient red band in the main illumination light with the sub illumination light, and emits the illumination light with sufficient light quantity in the direction of the arrow X.
JP 2002-296680 A

  By the way, in the conventional illumination optical device described above, in order to increase the amount of light in the red wavelength band, the light in the red wavelength band in the main illumination light is blocked by the reflective hologram element 17, and instead the output light of the sub-light source 8. Is output together with the main illumination light, so that heat is generated when the light in the red wavelength band is blocked, and there is a problem that means for releasing this heat is required. Further, in the conventional illumination optical device, the loss at the polarization conversion element 12 is large, and the energy lost here becomes heat, and this heat is applied to a part of the λ / 2 plate of the polarization conversion element made of an organic film. There is a problem of adverse effects. Further, there is a problem that the polarization conversion element is expensive. Further, since the conventional illumination device uses a semiconductor laser as a sub-light source, there is a problem that power consumption increases and the cost is increased. Here, it is conceivable that the auxiliary light source is constituted by a red LED or the like. However, when comparing the light quantity of the red LED and the light quantity of the ultra-high pressure mercury lamp in the same wavelength band, the latter is larger. If the sub-light source in the conventional illumination optical device is replaced with a red LED from a semiconductor laser, the red wavelength band is not only a red LED for obtaining illumination light that compensates for the shortage of the green wavelength band compared to the blue wavelength band, It is necessary to provide a red LED for recovering the amount of light in the red wavelength band in the main illumination light to be shielded. Therefore, it is necessary to provide a very large number of red LEDs as sub-light sources, which is not practical.

  The present invention has been made in view of the circumstances described above, and synthesizes light from a plurality of light sources without waste without performing light shielding that causes heat generation and without causing light loss due to polarization conversion. An object of the present invention is to provide an illumination optical device that can output the output.

The present invention includes a main light source that outputs main illumination light, a sub light source that outputs sub illumination light, a condenser lens that collects the main illumination light and the sub illumination light at a common focal point, and an incident surface at a focal point of the condenser lens. And a rod integrator that outputs illumination light obtained by adding the main illumination light and the sub illumination light from the exit surface.
According to this invention, the main illumination light and the sub-illumination light can be added without using means such as light shielding and polarization conversion, and the desired wavelength intensity characteristic is obtained without causing unnecessary heat generation and light loss. Illumination light can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>
FIG. 1 is a side view showing the configuration of a DLP (registered trademark) (Digital Light Processing (registered trademark)) type projector having an illumination optical apparatus 100 according to the first embodiment of the present invention. FIG. 2 is a perspective view showing a schematic configuration of the illumination optical device 100. In FIG. 2, the condenser lens 130 in FIG. 1 is not shown in order to prevent the drawing from becoming complicated.

  In the illumination optical device 100, the main light source 110 is similar to the main light source 6 in FIG. 4 described above, and an ultra high pressure mercury lamp 111, and a reflector 112 that reflects the output light from the ultra high pressure mercury lamp 111 and outputs it as parallel light. It is comprised by. The sub-light source 120 includes a red LED 121 and a collimating lens 121 that uses the output light from the red LED 121 as parallel light, and is provided around the opening of the reflector 112. More specifically, as shown in FIG. 2, an annular support member 123 is fixed around the opening of the reflector 112, and a plurality of auxiliary light sources 120 are fixed thereto. The secondary light source 120 outputs parallel light in a direction parallel to the parallel light output direction of the main light source 110.

  The condenser lens 130 and the rod integrator 150 constitute light adding means for adding and homogenizing the output light of the main light source 110 and the output light of the sub light source 120 to output illumination light. First, the condenser lens 130 condenses the parallel light from the main light source 110 and the parallel light from the sub light source 120 described above on a common focus. The rod integrator 150 is a means for adding the light from the main light source 110 and the light from the sub-light source 120 supplied toward the focal point in this way, with the incident surface positioned at the focal point of the condenser lens 130. It is fixed. The color wheel 140 is a means for switching the color of the output light of the illumination optical device 100 in a time division manner such as R, G, B, R,..., And is a position between the condenser lens 130 and the rod integrator 150. Is provided. As shown in FIG. 2, the color wheel 140 is formed of a fan-shaped color filter that transmits light of each color of R, G, and B, and is rotationally driven as shown in the figure while the image is projected by the projector. . Light from the condenser lens 130 reaches the incident surface of the rod integrator 150 via the color wheel 140.

  The light of the color selected by the color wheel 140 from the output light from the main light source 110 and the light of the color selected by the color wheel 140 from the output light from the sub-light source 120 are incident on the incident surface of the rod integrator 150. To do. These incident lights propagate toward the exit surface while being reflected by the inner wall surface of the rod integrator 150. In this propagation process, the output light from the main light source 110 and the output light from the sub-light source 120 are agitated and output as a homogenized light from the exit surface of the rod integrator 150. The output light from the rod integrator 150 is converted into parallel light by passing through the relay system 160 and output as output light of the illumination optical device 100. As described above, in the present embodiment, the output light of the main light source 110 and the output light of the sub light source 120 are combined without using light shielding or polarization conversion that causes heat generation, and the combined illumination light is transmitted to the projector. Sent to projection means. Hereinafter, the configuration of the projection means will be described.

  The TIR prism (inner total reflection prism) 201 is a prism in which two or more prisms are bonded together and an air layer is provided on the prism boundary surface 201A, and reflects incident light at a critical angle or more, within a critical angle. It has the characteristic of transmitting the incident light. In the optical system according to the present embodiment, the light emitted from the relay system 160 enters the TIR prism 201, enters the boundary surface 201A of the prisms at an incident angle greater than the critical angle, and passes from the DMD 202 to the TIR prism 201 side. The reflected light is designed to be incident at an incident angle within a critical angle. Therefore, the light incident on the TIR prism 201 from the relay system 160 is reflected at the boundary surface 201A between the prisms and incident on the DMD 202, and the reflected light from the DMD 202 side is projected from the boundary surface 201 of the TIR prism 201 to the projection lens 203. Permeate to the side.

  The DMD 202 is an array in which mirrors corresponding to a plurality of pixels constituting the screen are arranged in a plane, and each mirror in this array is tilted by image data designating ON / OFF of each pixel. That is, for the mirror corresponding to the pixel to be turned on, the light from the TIR prism 201 is reflected to the TIR prism 201 side, and for the mirror corresponding to the pixel to be turned off, the light from the TIR prism 201 is reflected to the TIR prism 201. The direction of each mirror corresponding to ON / OFF of each pixel is controlled such that the light is reflected in a direction different from the side where 201 exists. The drive control of the DMD 202 is performed in synchronization with the rotational drive of the color wheel 130 described above. That is, when illumination light of a certain color is supplied from the illumination optical device 100 to the DMD 202, the mirror corresponding to each pixel is driven by the image data of that color, and so on, corresponding to each color of R, G, and B. The illumination light color switching control by the illumination optical device 100 and the color switching control of the driving image data in the DMD 202 are performed in synchronization. As a result, the projection lens 203 displays a color image on a screen (not shown).

  According to the present embodiment described above, it is possible to synthesize illumination lights of different types of light sources without waste without using means such as light shielding and polarization conversion that cause heat generation, and a desired light source that cannot be realized with only a specific light source. Illumination light having wavelength intensity characteristics can be obtained. In addition, according to the present embodiment, the amount of light required for the sub-light source can be reduced by using the amount of light in the red wavelength band of the main illumination light as it is, and making up for the shortage compared to other wavelength bands by the sub-light source. Less than conventional illumination optical devices. Therefore, a red LED can be used as a sub-light source instead of a semiconductor laser. Most of the emitted light of the red LED is visible light and does not contain infrared light. Therefore, when a red LED is used as the auxiliary light source, there is an advantage that heat generation due to illumination loss can be reduced.

Second Embodiment
FIG. 3 is a side view showing the configuration of a three-plate DLP (registered trademark) projector having the illumination optical apparatus 100A according to the second embodiment of the present invention. Unlike the illumination optical apparatus 100 according to the first embodiment, the illumination optical apparatus 100A according to the present embodiment does not include the color wheel 140. Instead, the projector is provided with means for branching the illumination light obtained from the illumination optical device 100A into a path determined for each color component. Specifically, it is as follows.

  The mirror 301 bends (deflects) illumination light emitted through the relay system 160 of the illumination optical apparatus 100A by about 90 degrees and makes it incident on the TIR prism 302. The optical system in the present embodiment is designed so that light emitted from the relay system 160 enters the TIR prism 302 and enters a boundary surface 302a between the prisms at a critical angle or more. Therefore, the light incident on the TIR prism 302 from the relay system 160 is reflected on the boundary surface 302 a between the prisms and enters the dichroic prism 303.

  In the dichroic prism 303, wavelength selective spectroscopy of the light incident from the TIR prism 302 is performed, and the separated R, G, and B lights enter the DMDs 310R, 310G, and 310B. In DMDs 310 </ b> R, 310 </ b> G, and 310 </ b> B, the mirror that hits the pixel is tilted based on the image data, and the light reflected by the mirror in the ON state enters the dichroic prism 303 again. In the dichroic prism 303, the lights from the DMDs 310 R, 310 G, and 310 B are combined and enter the TIR prism 302.

  The optical system in the present embodiment is designed such that incident light from the dichroic prism 303 enters the boundary surface 302a between the prisms in the TIR prism 302 within a critical angle. Therefore, the incident light passes through the boundary surface 302a and enters the projection lens 203, and an image is enlarged and displayed on the screen.

<Other embodiments>
(1) In each of the embodiments described above, the illumination optical device has been described by taking the case of application to a DLP projector as an example. However, in addition to the DLP system, there are various projectors such as an LCOS (Liquid Crystal On Silicon) system projector and a transmissive LCD projector. The illumination device according to the present invention can be applied to various projectors regardless of the display element or the optical system by making necessary modifications according to the system of the projector.
(2) In each said embodiment, red LED was used as a sublight source. However, instead of this, a green LED or the like may be used. In addition, LEDs of complementary colors such as yellow and magenta may be used as the sub-light source.

1 is a side view illustrating a configuration of a projector having an illumination optical device according to a first embodiment of the present invention. It is a perspective view which shows schematic structure of the illumination optical apparatus in the embodiment. It is a side view which shows the structure of the projector which has the illumination optical apparatus which is 2nd Embodiment of this invention. It is a figure which shows the structure of the conventional illumination optical apparatus.

Explanation of symbols

110: Main light source, 120: Sub light source, 130: Condenser lens, 150: Rod integrator

Claims (3)

A main light source that outputs main illumination light;
A secondary light source that outputs secondary illumination light;
A condenser lens that collects the main illumination light and the sub-illumination light at a common focal point;
An illumination optical apparatus comprising: a rod integrator that positions an incident surface at a focal point of the condenser lens and outputs illumination light obtained by adding the main illumination light and the sub illumination light from the emission surface.     The said sub light source is provided with two or more surrounding the circumference | surroundings of the said main light source, and each outputs the sub illumination light parallel to the said main illumination light toward the said condenser lens. Illumination optical device.   The illumination optical apparatus according to claim 1, wherein the sub-light source outputs light in a specific wavelength band that is a part of a wavelength band of output light of the main light source.

Images