JP5573025B2 - Illumination optical system and projector apparatus using the illumination optical system - Google Patents

Description

  The present invention relates to an illumination optical system and a projector apparatus using the illumination optical system.

  A display element such as a liquid crystal device (LCD, LCOS) or DMD is used as a light valve, and illumination light is irradiated to the display element in order to reduce the size of a projector apparatus that enlarges and projects the display image onto a screen or the like by a projection optical system. For this purpose, a high-intensity white LED is used. This high-intensity white LED is generally realized by a blue LED and a YAG (yttrium, aluminum, garnet) -based phosphor layer disposed in front of the blue LED, and the phosphor layer is a blue LED. Absorbs part of the light and generates yellow component light. (For example, refer to Patent Document 1).

JP 2008-268639 A

  However, when the phosphor layer is provided on the front surface of the blue LED, the distance in the phosphor layer through which the light is transmitted differs depending on the direction of light emitted from the blue LED (emission angle). There has been a problem that the color temperature of the white light becomes uneven, and as a result, the color temperature becomes non-uniform in the projector screen.

  The present invention has been made in view of such a problem, and provides an illumination optical system in which the color temperature of illumination light (white light) irradiated on a display element is made uniform, and a projector apparatus using the illumination optical system. The purpose is to do.

In order to solve the above-described problems, an illumination optical system according to the present invention includes a condensing optical system that condenses light from a light source into substantially parallel light and irradiates an illuminated member, and A color temperature conversion member that is arranged on an optical path through which substantially parallel light passes between the illumination member and the color temperature of the transmitted light, and is arranged between the condensing optical system and the illumination target member, and is illuminated possess a polarization conversion element to align the polarization directions of light irradiated to a member, the exit surface polarization conversion element, an incident surface which light from the focusing optical system is incident, in which the polarization directions are aligned light emitted And at least part of the light having a predetermined polarization component and the light having a polarization component different from the predetermined polarization component converted into the predetermined polarization component among the light incident from the incident surface. It is configured to emit from the exit surface so that it does not overlap, and the color temperature conversion member is attached to the entrance surface. The light from the light source incident on the incident surface is changed in color temperature by the color temperature conversion member, and is emitted from the emission surface in a state where the width is wider than the width of the light incident on the incident surface. The area of the conversion member is smaller than the area of the illuminated member to which the light emitted from the emission surface is irradiated.

In such an illumination optical system, the polarization conversion element includes: an incident surface; and a first polarization separation surface that transmits P-polarized component light and reflects S-polarized component light out of light incident from the incident surface; A first exit surface that is a part of the exit surface and emits P-polarized component light that has been transmitted through the first polarization separation surface, and S-polarized component light that is reflected by the first polarization separation surface A second polarization separation surface that reflects in the substantially same direction as the light emission direction of the polarization component light, and S-polarized light that is a portion of the emission surface other than the first emission surface and reflected by the second polarization separation surface The second emission surface that emits the component light and the polarization plane of either the P-polarized component light emitted from the first emission surface or the S-polarized component light emitted from the second emission surface It is preferable to have a rotating surface that rotates 90 °.

  In addition, such a polarization conversion element includes a polarization separation element having an incident surface, a first polarization separation surface, a second polarization separation surface, a first exit surface, and a second exit surface, and a half surface having a rotation surface. It is preferable to have a wave plate.

  Such an illumination optical system preferably has a stop between the condensing optical system and the polarization conversion element.

Further, such an illumination optical system has a polarization separation surface, and is disposed on an optical path between the condensing optical system and the illumination target member, and transmits or reflects light on the polarization separation surface to be illuminated member. It is preferable to have a polarizing beam splitter that irradiates the light beam.

  In such an illumination optical system, the condensing optical system is preferably a condensing lens group. Alternatively, the condensing optical system is preferably a condensing mirror.

  In addition, a projector device according to the present invention includes a light source, a display element that is a member to be illuminated, one of the above-described illumination optical systems that irradiates the display element with light from the light source, and light reflected by the display element or the display element. And a projection lens group that projects the image of the display element by condensing the light transmitted through.

In such a projector device, the light source is an LED light source that emits blue component light, and the color temperature conversion member absorbs part of the blue component light and emits yellow component light, and transmits the rest. The phosphor is preferably made to be a phosphor.
In such a projector apparatus, it is preferable that the condensing optical system is designed with optical performance based on blue component light.

  In such a projector device, the display element is preferably a liquid crystal element.

  When the illumination optical system according to the present invention and the projector device using the illumination optical system are configured as described above, the color temperature of illumination light (white light) irradiated on the display element can be made uniform.

It is explanatory drawing of the projector apparatus which has the illumination optical system which concerns on 1st Embodiment. It is explanatory drawing of the projector apparatus which has the illumination optical system which concerns on 2nd Embodiment, Comprising: The case where a color temperature conversion member is provided in the entrance plane of the polarization conversion element is shown. It is explanatory drawing of the projector apparatus which has the illumination optical system which concerns on 2nd Embodiment, Comprising: The case where a color temperature conversion member is provided in the entrance plane of the polarization beam splitter is shown.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
First, the configuration of a projector apparatus having an illumination optical system according to the first embodiment will be described with reference to FIG. The projector device 10 is composed of a single color LED that emits blue component light (hereinafter referred to as “blue light”), a light source 1 that emits the blue light as illumination light, and a blue light emitted from the light source 1. Illuminating optical system 11 that irradiates the reflective display element 5 (for example, LCOS (reflective liquid crystal display panel in which a liquid crystal is formed on a silicon substrate)) that is a member to be illuminated by converting the light into white light, And a projection optical system 12 that magnifies and projects an image of light reflected by the display element 5 onto a projection surface (screen or the like) as a real image.

  The illumination optical system 11 is provided between the light source 1 and the display element 5, and in order from the light source 1 side, the condensing lens group 2 which is an embodiment of the condensing optical system, and the YAG-based fluorescence described above. A color temperature conversion member 3 made of a body (hereinafter referred to as “yellow phosphor”) and a polarizing beam splitter 4 are arranged in this order on the optical axis. The projection optical system 12 shares the illumination optical system 11 and the polarization beam splitter 4, and the polarization beam splitter 4 and the projection lens group 6 are arranged on the optical axis in this order from the display element 5 side. Has been placed. The light source 1 includes a light emitting unit (for example, an LED chip) 1a that emits blue light and a cover 1b that is made of a transparent member and covers and protects the light emitting unit 1a. The color temperature conversion member 3 is configured by applying a yellow phosphor on the surface of the polarizing beam splitter 4 on the light source 1 side. The surface on the light source 1 side of the polarizing beam splitter 4 is a surface substantially orthogonal to the optical axis. By applying the surface of such an optical member to form a phosphor layer, the color temperature conversion member 3 can be easily formed. Can be configured.

  In the projector device 10 having such a configuration, the illumination light (blue light) emitted from the light emitting unit 1a of the light source 1 is condensed by the condenser lens group 2 and converted into substantially parallel light, and then converted into color temperature. Incident on the member 3. This color temperature conversion member 3 absorbs a part of incident blue light, emits yellow component light (yellow light), and transmits the remaining light to convert it into white light. Therefore, the blue light incident on the color temperature conversion member 3 is converted into white light and emitted, and further incident on the polarization beam splitter 4. Of the white light incident on the polarization beam splitter 4, the P-polarized component light is transmitted through the polarization separation surface 4a and emitted from the polarization beam splitter 4, and the S-polarization component light is emitted from the polarization separation surface 4a. And is irradiated onto the display surface 5a of the display element 5.

  The display element 5 according to the present embodiment is a liquid crystal panel (LCOS) in which a liquid crystal is interposed between a silicon substrate and a glass substrate, and switching elements such as TFTs and electrodes are provided on each of the sub-pixels on the silicon substrate. It is provided corresponding to the pixel. An aluminum layer that reflects light is formed on the outermost surface of the silicon substrate. Then, the liquid crystal layer interposed between the transparent electrode and the glass substrate can be electrically driven to display an image. By controlling the application of voltage to the electrodes provided in each pixel of the display element 5 based on the level of the video signal input from a drive circuit (not shown), each of the display elements 5 is controlled according to the level of the video signal. When a voltage is applied to the electrodes, the arrangement of liquid crystal molecules in the liquid crystal layer changes, and this liquid crystal layer serves as a phase plate. As a result, a video pattern corresponding to the voltage application state is formed on the display element 5, and spatial light modulation is performed. That is, the S-polarized component light incident from the glass substrate side of the display element 5 is reflected by the reflecting surface (aluminum layer) on the silicon substrate side and is emitted from the glass substrate again, but is incident on the white pixel portion in the meantime. The polarization direction of the S-polarized light component is rotated by 90 ° and modulated (polarized light) into the P-polarized light component. On the other hand, the light of the S-polarized component incident on the black pixel portion is emitted as the S-polarized component without changing the polarization state. The display element 5 can display a color image by using a color display LCOS provided with a color filter.

  Then, the light reflected by the display surface 5 a of the display element 5 enters the polarization beam splitter 4 again. Here, most of the S-polarized component light transmitted through the black pixel portion of the display element 5 is reflected by the polarization separation surface 4a and returns to the light source 1 side. On the other hand, the P-polarized component light modulated and emitted from the white pixel portion of the display element 5 is transmitted through the polarization separation surface 4a and then emitted from the polarization beam splitter 4, and projected onto a screen (not shown) by the projection lens group 6. Is done. As a result, an enlarged image of the image displayed on the display element 5 is projected on the screen.

  As described above, the color temperature conversion member 3 for converting the blue light emitted from the light source 1 into the white light is used in the case where the illumination light becomes substantially parallel light, that is, a polarized beam on which the illumination light (blue light) is incident. By arranging on the surface of the splitter 4 on the light source 1 side, the blue light is transmitted through the color temperature conversion member 3 in the thickness direction as parallel light, so that the blue light transmitted through the color temperature conversion member 3 is transmitted. The transmission distance becomes uniform, so that the color temperature of the white light emitted from the color temperature conversion member 3 can be made uniform. Further, in the condenser lens group 2 that condenses the light emitted from the light source 1 by refractive power, its optical performance can be designed based on monochromatic light (blue light), and therefore aberration (particularly chromatic aberration). Etc.) and the degree of freedom in design is improved. In the above description, the case where the color temperature conversion member 3 is disposed on the incident side surface of the polarization beam splitter 4 has been described. However, the color temperature conversion member 3 is disposed on the surface of the polarization beam splitter 4 on the display element 5 side (yellow fluorescent light). It is also possible to apply the body. Alternatively, the color temperature conversion member 3 can be configured as an optical element independent of the polarization beam splitter 4 (for example, configured by applying a yellow phosphor on the surface of a transparent parallel plate-shaped optical member). . Also in this case, the color temperature conversion member 3 is disposed between the condenser lens group 2 and the display element 5 in the illumination optical system 11 and on the optical path where the illumination light is in a substantially parallel light state. Thus, the color temperature of the white light emitted from the color temperature conversion member 3 can be made uniform.

  The display element 5 can also be configured to project the S-polarized component light, which is illuminated with the P-polarized component light and spatially modulated by the white pixel portion, with the projection lens group 6. In the case of such a configuration, the display element 5 is disposed on the surface side where the illumination light passes through the polarization separation surface 4a and exits with respect to the polarization beam splitter 4, and the projection optical system 6 includes the display element. The light reflected by 5 is arranged on the surface side that is reflected by the polarization separation surface 4a and emitted.

[Second Embodiment]
Next, the configuration of the projector apparatus having the illumination optical system according to the second embodiment will be described with reference to FIG. The projector device 110 also includes a light source 101 that emits blue illumination light, an illumination optical system 111 that converts blue light emitted from the light source 101 into white light, and irradiates the reflective display element 105, and the display element. And a projection optical system 112 that magnifies and projects the image of the light reflected by 105 on a projection surface (screen or the like) as a real image.

  The illumination optical system 111 includes, in order from the light source 101 side, a condensing lens group 102 that is an embodiment of the condensing optical system, a diaphragm 120, a color temperature conversion member 103 made of a yellow phosphor, and a polarization conversion element 121. The polarizing beam splitter 104 is arranged in this order on the optical axis. The projection optical system 112 shares the illumination optical system 111 and the polarization beam splitter 104, and the polarization beam splitter 104 and the projection lens group 106 are arranged on the optical axis in this order from the display element 105 side. Has been placed. In the illumination optical system 11 according to the first embodiment described above, the illumination light emitted from the light source 1 and converted into white light by the color temperature conversion member 3 is applied to the display element 5 via the polarization beam splitter 4. However, the light emitted to the display element 5 is only the S-polarized light component reflected by the polarization separation surface 4a of the polarization beam splitter 4 in the white light. Therefore, the utilization efficiency of the illumination light radiated from the light source 1 is lowered. Therefore, in the illumination optical system 111 according to the second embodiment, the polarization conversion element 121 is provided to align the illumination light with the light of the S polarization component.

  The polarization conversion element 121 includes a polarization separation element 122 and a half-wave plate 123. The polarization separation element 122 has substantially the same size as the aperture of the stop 120, and is incident from an incident surface 122a on which illumination light is incident vertically and a substantially central portion (a point intersecting the optical axis) of the incident surface 122a. Two first polarization separation surfaces 122b extending in a V shape at an angle of 45 degrees with respect to the surface 122a, and two second polarization layers arranged substantially parallel to each of the first polarization separation surfaces 122b A first exit surface 122d, which is substantially the same size as the polarization separation surface 122c and is aligned with the entrance surface 122a and arranged substantially parallel to the entrance surface 122a, is substantially the same as the upper and lower sides of the first exit surface 122d. Two second exit surfaces 122e arranged side by side on the surface, and the display surface 105 side of the first exit surface 122d is substantially the same as the first exit surface 122d. A half-wave plate 123 having a shape is attached. Here, the half-wave plate 123 has a function as a rotation surface that rotates the polarization plane of the transmitted light by 90 °. In the illumination optical system 111, the color temperature conversion member 103 has substantially the same size as the incident surface 122a of the polarization separation element 122, and is provided on the surface of the incident surface 122a on the light source 101 side (yellow). A phosphor is applied to the incident surface 122a).

  In the projector device 110 having such a configuration, the blue light emitted from the light source 101 is converted into substantially parallel light by the condenser lens group 102, enters the color temperature conversion member 103, is converted into white light, and is incident. The light enters the polarization separation element 122 from the surface 122a. Since the diaphragm 120 is provided on the light source 101 side of the polarization separation element 122, illumination light (blue light) does not enter other than the color temperature conversion member 103 provided on the incident surface 122a. Then, the white light incident from the incident surface 122a is divided into upper and lower parts and incident on the two first polarization separation surfaces 122b, and most of the light of the P-polarized component of the white light is the first polarization separation. Most of the S-polarized component light is transmitted through the surface 122b and reflected by the first polarization separation surface 122b in a direction substantially perpendicular to the optical axis. Then, the P-polarized component light transmitted through the first polarization separation surface 122b is incident on the half-wave plate 123 from the first emission surface 122d as substantially parallel light, and the polarization plane is rotated by 90 ° by the half-wave plate 123. And emitted as S-polarized light. On the other hand, the S-polarized component light reflected by the first polarization separation surface 122b is further reflected by the second polarization separation surface 122c to become light substantially parallel to the optical axis, and is emitted from the second exit surface 122e. The That is, most of the white light incident on the polarization conversion element 121 is emitted as white parallel light composed of S-polarized light. For this reason, most of the white light incident on the polarization beam splitter 104 is reflected by the polarization separation surface 104 a and applied to the display surface 105 a of the display element 105. Of the light subjected to spatial light modulation on the display surface 105a of the display element 105, the P-polarized component light that has passed through the white pixel portion passes through the polarization separation surface 104a and is then emitted from the polarization beam splitter 104. The projection lens group 106 projects the image onto a screen (not shown).

  As described above, the polarization conversion element 121 is provided in the illumination optical system 111 constituting the projector device 110, and the illumination light emitted from the light source 101 is separated into S-polarized component light and P-polarized component light. By emitting the light as it is and converting the light of the P-polarized light component into the light of the S-polarized light component, the light that passes through the polarization separation surface 104a of the polarizing beam splitter 104 and is not irradiated on the display element 105 is reduced, and the use of the illumination light Efficiency can be increased. As a result, a bright image can be projected even when the light source 101 with low luminance is used, and the power consumed by the light source 101 can be reduced. Further, by increasing the utilization efficiency of the light emitted from the light source 101, heat generation of the projector device 110 can be suppressed, and the projector device 110 can be downsized.

  Similarly to the first embodiment, the color temperature conversion member 103 for converting the blue light emitted from the light source 101 into white light is used in a place where the illumination light becomes substantially parallel light, that is, the polarization conversion element 121. By arranging the light incident surface 122a on the light source 101 side, the color temperature of the white light emitted from the color temperature conversion member 103 can be made uniform. Further, in the condensing lens group 102 that condenses the light emitted from the light source 101 by refractive power, the optical performance can be designed based on monochromatic light (blue light). Etc.) and the degree of freedom in design is improved.

  Furthermore, as in the first embodiment, the position where the color temperature conversion member 103 is disposed is not limited to the incident surface 122a of the polarization conversion element 121. For example, as in the illumination optical system 111 ′ used in the projector apparatus 110 ′ shown in FIG. 3, the color temperature conversion member 103 ′ is disposed on the surface on which the illumination light (blue light) is incident on the polarization beam splitter 104. Is also possible. As described above, since the S-polarized component light emitted from the polarization conversion element 121 is substantially parallel light, the color temperature of the white light emitted through the color temperature conversion member 103 ′ is made uniform. Can do. In this case, since the illumination light transmitted through the polarization conversion element 121 is blue light, the optical performance of the first and second polarization separation surfaces 122b and 122c can be designed based on monochromatic light (blue light). And the degree of freedom in design is improved. Here, in the projector apparatus 110 ′ shown in FIG. 3, the same reference numerals are given to the constituent members having the same functions as those of the projector apparatus 110 shown in FIG.

  By the way, as described in the first embodiment, the display element 105 projects the light of the S-polarized light component that is illuminated with the light of the P-polarized light component and spatially modulated in the white pixel portion by the projection lens group 106. The arrangement of the polarizing beam splitter 104, the display element 105, and the projection lens group 106 in such a configuration is the same as that described in the first embodiment. In this case, the half-wave plate 123 constituting the polarization conversion element 121 is attached to the second exit surface 122e of the polarization separation element 122, and the light of the S-polarized component exiting from the second exit surface 122e is P. It is comprised so that it may convert into the light of a polarization component.

  In the illumination optical systems 11, 111, and 111 ′ according to the first and second embodiments described above, a condensing lens is used as a condensing optical system that converts blue light emitted from the light sources 1 and 101 into substantially parallel light. Although the case where the groups 2 and 102 are used has been described, it is also possible to use a condensing mirror having a parabolic reflecting surface. In this case, substantially parallel light can be obtained by arranging the light sources 1 and 101 on the focal point of the paraboloid. In the above description, LCOS (Liquid Crystal on Silicon), which is a reflective liquid crystal element, has been described as an example of the display elements 5 and 105. However, the present invention is not limited to this display element, and reflective A DMD (Digital Mirror Device) can be used as the display device of the type, and an LCD (Liquid Crystal Display) which is a transmissive liquid crystal device can also be used.

1,101 Light source 2,102 Condensing lens group (condensing optical system)
3, 103, 103 'Color temperature conversion member 4, 104 Polarization beam splitter 5, 105 Display element (illuminated member) 6, 106 Projection lens group 10, 110, 110' Projector device 120 Aperture 121 Polarization conversion element 122 Polarization separation element 122a Incident surface 122b First polarization separation surface 122c Second polarization separation surface 122d First exit surface 122e Second exit surface 123 Half-wave plate

Claims (11)

A condensing optical system for condensing the light from the light source into substantially parallel light and irradiating the illuminated member;
A color temperature conversion member that is disposed on an optical path through which the substantially parallel light passes between the condensing optical system and the illumination target member, and changes a color temperature of the transmitted light;
A polarization conversion element that is disposed between the condensing optical system and the illuminated member and aligns the polarization direction of the light irradiated on the illuminated member;
The polarization conversion element has an incident surface on which light from the condensing optical system is incident, and an exit surface on which the polarization direction is aligned, and the light is emitted. The polarization component light and the polarization component light different from the predetermined polarization component are emitted from the exit surface so that at least part of the light converted into the predetermined polarization component does not overlap. ,
The color temperature conversion member is attached to the incident surface, and the light from the light source incident on the incident surface changes in color temperature at the color temperature conversion member, compared to the width of the light incident on the incident surface. Injecting from the exit surface in a wide state,
An illumination optical system, wherein an area of the color temperature conversion member is smaller than an area of the illumination target member irradiated with light emitted from the emission surface. The polarization conversion element is:
The incident surface;
Of the light incident from the incident surface, a first polarization separation surface that transmits P-polarized component light and reflects S-polarized component light;
A first exit surface that is part of the exit surface and that emits light of the P-polarized component that has passed through the first polarization separation surface;
A second polarization separation surface that reflects the light of the S polarization component reflected by the first polarization separation surface in substantially the same direction as the light emission direction of the P polarization component;
Of the exit surface, a portion other than the first exit surface, the second exit surface for emitting the light of the S-polarized component reflected by the second polarization separation surface,
A rotating surface that rotates the polarization plane of either the P-polarized light component emitted from the first exit surface or the S-polarized component light exited from the second exit surface by 90 °. The illumination optical system according to claim 1. The polarization conversion element is:
A polarization separation element having the entrance surface, the first polarization separation surface, the second polarization separation surface, the first exit surface, and the second exit surface;
The illumination optical system according to claim 2, further comprising a half-wave plate having the rotation surface.   The illumination optical system according to any one of claims 1 to 3, further comprising a stop between the condensing optical system and the polarization conversion element. A polarized beam that has a polarization separation surface, is disposed on an optical path between the condensing optical system and the illumination target member, and irradiates the illumination member by transmitting or reflecting the light on the polarization separation surface. The illumination optical system according to claim 1, further comprising a splitter.   The illumination optical system according to claim 1, wherein the condensing optical system is a condensing lens group.   The illumination optical system according to claim 1, wherein the condensing optical system is a condensing mirror. A light source;
A display element that is an illuminated member;
The illumination optical system according to any one of claims 1 to 7, wherein the display element is irradiated with light from the light source;
And a projection lens group configured to collect the light reflected by the display element or the light transmitted through the display element and project an image of the display element. The light source is an LED light source that emits light of a blue component,
The projector according to claim 8, wherein the color temperature conversion member is a phosphor that absorbs part of the blue component light, emits yellow component light, and transmits the remaining light.   The projector apparatus according to claim 9, wherein the condensing optical system is designed with optical performance based on light of a blue component.   The projector device according to claim 8, wherein the display element is a liquid crystal element.

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