JP2010122289A - Projector - Google Patents

Abstract

A projector that can be reduced in size and cost is provided.
A projector 1 according to the present invention reflects a light source device 10, a polarization separation element 15 that reflects a first polarization L12 emitted from the light source device 10 and transmits a second polarization L13, and a polarization separation element 15. The light modulation device 17 that changes the polarization state of the first polarization L12 and reflects the first polarization L12, the condensing lens 12 disposed between the light source device 10 and the polarization separation element 15, the condensing lens 12 and the polarization A field lens 14 disposed between the separation element 15 and an imaging lens 16 disposed between the polarization separation element 15 and the light modulation device 17 are provided. Koehler illumination includes the light source device 10, the condenser lens 12, the field lens 14, and the imaging lens 16. A projection optical system that includes the imaging lens 16 and projects light emitted from the light modulation device and transmitted through the polarization separation element 15 is configured.
[Selection] Figure 1

Description

  The present invention relates to a projector.

  A projector is known as one of devices capable of displaying a large screen image. The projector includes an illumination device, an image forming device, a projection lens, and the like. The illumination light emitted from the illumination device becomes image light indicating an image by the image forming apparatus. The image light is enlarged and projected by a projection lens, and a large screen image can be obtained more easily than a direct-view image display device.

  As a projector illumination device, an illumination device using a lamp light source is known. In order to improve the image quality of the projector, it is important to make the illuminance distribution uniform in the illuminated area of the image forming apparatus illuminated by the illumination device. A fly-eye lens array is known as an illuminance equalizing element that makes illuminance uniform in an illumination device using a lamp light source. In general, a fly-eye lens array is formed by arranging a plurality of lenses, and two fly-eye lens arrays are used as a pair.

  As a projector image forming apparatus, a transmissive or reflective liquid crystal light valve is known. As a projector using a reflective liquid crystal light valve, there is a projection type image display device disclosed in Patent Document 1.

  In the projection type image display device of Patent Document 1, a polarizing mirror inclined with respect to the illumination optical axis is disposed between the illumination optical system and the reflective liquid crystal display panel. A cross dichroic prism is disposed between the polarizing mirror and the liquid crystal display panel. From the illumination optical system, the illuminance distribution is made uniform by the pair of fly-eye lens arrays, and the polarized light whose polarization state is made uniform by the polarization conversion element is emitted. This polarized light enters the cross dichroic prism through the polarizing mirror, and is separated into a plurality of color lights having different wavelengths by the cross dichroic prism.

The separated color lights are incident on the corresponding liquid crystal display panels to change the polarization state, reflected by the liquid crystal display panel, turned back, and again incident on the cross dichroic prism. Then, a plurality of color lights are synthesized by the cross dichroic prism, and the synthesized light is incident on the polarization mirror. A part of the light incident on the polarizing mirror is reflected and bent by the polarizing mirror according to the polarization state, and is incident on the projection optical system and enlarged and projected.
JP 2007-58108 A

  In the projection type image display device of Patent Document 1, by using a reflective liquid crystal light valve, the dichroic prism can be provided with a color separation function and a color composition function, and the size of the device can be reduced. It has become. However, the projector is expected to further reduce the size of the device and reduce the cost of the device, and it is difficult to meet such expectation only by applying the technique of Patent Document 1.

  In Patent Document 1, since light emitted from a liquid crystal display panel is projected after being reflected by a polarizing mirror, high accuracy is required for the position of the polarizing mirror with respect to the liquid crystal display panel and the position of the projection optical system with respect to the polarizing mirror. Is done. This is because if the position of the polarizing mirror includes an error in either the translation direction or the rotation direction, the projection optical system cannot function normally, and the image quality deteriorates.

  If it is intended to ensure the positional accuracy of the polarizing mirror, an advanced alignment technique is required, resulting in an increase in manufacturing cost. Moreover, since the illuminance of light emitted from the light source device is made uniform by a pair of fly-eye lenses as in a normal projector, the fly-eye lens may interfere with downsizing the device.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a projector capable of reducing the size of the device and reducing the cost of the device.

  The projector of the present invention includes a light source device that emits light, and a polarization separation element that reflects the first polarized light of the light emitted from the light source device and transmits the second polarized light having a polarization direction different from the first polarized light. A light modulation device that is disposed at a position where the first polarized light reflected by the polarization separation element is incident, modulates the first polarized light and reflects it to the polarization separation element, the light source device, and the polarization separation element, A condensing lens disposed in the optical path between the condensing lens, a field lens disposed in the optical path between the condensing lens and the polarization separation element, and an optical path between the polarization separation element and the light modulation device. An imaging lens arranged, and comprising the light source device, the condenser lens, the field lens, and the imaging lens, Koehler illumination for illuminating the light modulation device is configured, and Comprise lenses, characterized in that the projection optical system is configured to project the light emitted passes through the polarization separating element from the optical modulation device.

  In this way, Kohler illumination is configured including the light source device, the condenser lens, the field lens, and the imaging lens, and the light modulation device can be illuminated with uniform illuminance by Koehler illumination. Therefore, an illuminance uniformizing element such as a fly-eye lens array that equalizes the illuminance of the illumination light can be omitted, and the number of components can be reduced.

  In addition, since the imaging lens serves as part of the configuration of the Koehler illumination and part of the configuration of the projection optical system, the number of parts can be reduced as compared with the case where the Koehler illumination is configured independently of the projection optical system. Can do.

  As described above, according to the above configuration, the number of components can be reduced, so that the projector can be reduced in size and the apparatus cost can be reduced.

  Further, since the light emitted from the light modulation device and transmitted through the polarization separation element is projected to become image light indicating an image, the image light is hardly affected by the position of the polarization separation element. The light modulation device is illuminated by light emitted from the light source device and reflected by the polarization separation element, but the uniformity of illuminance, which is a characteristic required for illumination light, is insensitive to the position of the polarization separation element. According to the above configuration, since the positional accuracy of the polarization separation element is not important for both image light and illumination light, the allowable range for the positional deviation of the polarization separation element is widened. Therefore, it is not necessary to use an advanced alignment technique for the arrangement of the polarization separation elements, and the apparatus cost of the projector can be reduced.

Further, it is preferable that the field lens is disposed at a position conjugate with the stop of the projection optical system.
In this way, since the Koehler illumination is optically equivalent to the projection optical system, the efficiency of the optical components constituting the Koehler illumination and the efficiency of the optical components constituting the projection optical system can be improved. The light utilization efficiency is increased.

Further, it is preferable that a polarization conversion element that converts light emitted from the light source device into the first polarized light is disposed in an optical path between the light source device and the polarization separation element.
In this way, the second polarized light contained in the light emitted from the light source device is converted into the first polarized light by the polarization conversion element and enters the polarization separation element. Therefore, the amount of light incident on the light modulation device is increased by the amount of the second polarization compared to the case where no polarization conversion element is provided, and the light use efficiency is increased.

Moreover, it is preferable that the said light source device is comprised by the solid light source.
This makes it easier to reduce the size of the device and to obtain high-power light than when the light source device is composed of a lamp light source.

Moreover, it is preferable that the Koehler illumination illuminates the light modulation device with light whose wavelength changes with time.
In this way, the light emitted from the Koehler illumination and whose polarization state has been changed by the light modulator changes the wavelength spatially or temporally. This light is visually recognized as light indicating a color image by visually recognizing the change in wavelength spatially or temporally. In short, a color display projector can be configured by one light modulation device, and the device can be made smaller than a color display projector using a plurality of light modulation devices.

  Hereinafter, although embodiment of this invention is described, the technical scope of this invention is not limited to the following embodiment. In the following description, various structures are illustrated using drawings, but in order to show the characteristic parts of the structures in an easy-to-understand manner, the structures in the drawings are shown in different sizes and scales from the actual structures. There is.

[First Embodiment]
1 to 3 are schematic diagrams illustrating a schematic configuration of the projector 1 according to the first embodiment. The projector 1 includes an illumination optical system, a light modulation device, and a projection optical system. In FIG. 1, the illumination optical axis 1A of the illumination optical system is illustrated by a one-dot chain line, and in FIG. 2, the projection optical axis 1B of the projection optical system is illustrated by a one-dot chain line. FIG. 3 shows an optical path of light emitted from the point light source when it is assumed that the point light source is arranged at the position of the light modulation device illuminated by the illumination optical system.

  As shown in FIGS. 1 and 2, the projector 1 includes a light source device 10 and a reflective liquid crystal light valve 17. The light emitted from the light source device 10 travels along the illumination optical axis 1 </ b> A and enters the liquid crystal light valve 17. Further, the projector 1 includes a projection lens group 19, and the light emitted from the liquid crystal light valve 17 travels along the projection optical axis 1 </ b> B and is enlarged and projected onto a projection surface such as a screen (not shown). Is done.

  As shown in FIG. 1, the illumination optical axis 1 </ b> A is bent approximately 90 ° by the reflection mirror 13 at the optical axis of the light source device 10, and then bent again by approximately 90 ° within the polarizing beam splitter prism (hereinafter referred to as PBS prism) 15. Is. On the illumination optical axis 1A between the light source device 10 and the reflection mirror 13, a color wheel 11 and a condenser lens 12 are arranged in this order from the light source device 10 side. A field lens 14 is disposed on the illumination optical axis 1 </ b> A between the reflection mirror 13 and the PBS prism 15. An imaging lens 16 is disposed on the illumination optical axis 1A between the PBS prism 15 and the liquid crystal light valve 17.

  As shown in FIG. 2, the projection optical system is configured without using a reflection optical system, and the projection optical axis 1 </ b> B coincides with the optical axis of the liquid crystal light valve 27. The projection optical axis 1B is coincident with the illumination optical axis 1A between the liquid crystal light valve 17 and the PBS prism 15. Therefore, the image light from the liquid crystal light valve 27 is enlarged and projected onto the screen without being reflected by the reflection optical system. A projection lens group 19 is disposed in front of the PBS prism 15 (on the projection surface side). A diaphragm 18 is disposed between the lens group 19 and the PBS prism 15.

  The light source device 10 includes a light source that emits light. As the light source, a lamp light source such as a high-pressure mercury lamp, a metal halide lamp, or a xenon lamp, or a solid light source such as a light emitting diode (LED) or a laser diode (LD) can be used. In the present embodiment, a light source device that emits white light using an LED as a light source is employed. If the light source device is configured by a solid light source, the light source device can be reduced in size, the output power of the emitted light can be increased, the light source can be instantly turned on and off, and the like. In the present embodiment, the light 11 emitted from the light source device 10 enters the color wheel 11.

  The color wheel 11 is, for example, a disk-shaped member that can rotate around the central axis. Three color filters having different wavelengths of light to be transmitted are provided in the plane of the color wheel 11. The three color filters are, for example, a red color filter that transmits red light, a green color filter that transmits green light, and a blue color filter that transmits blue light. The color wheel 11 is arranged so that the light L11 emitted from the light source device 10 passes through one of the three color filters. As the color wheel 11 rotates, which of the three color filters the light L11 passes through changes, and the wavelength of the light emitted from the color wheel 11 changes with time. The light L11 that has passed through the color wheel 11 enters the condenser lens 12.

  The condensing lens 12 is a lens that condenses the light L <b> 11 emitted from the light source device 10. The light L11 that has passed through the condenser lens 12 is incident on the reflection mirror 13. The reflection mirror 13 of the present embodiment is arranged so that the normal direction of the reflection surface forms an angle of approximately 45 ° with the illumination optical axis 1A. The light L <b> 11 is reflected by the reflection mirror 13, the optical axis is bent by approximately 90 °, and enters the field lens 14.

  Here, the light incident on the field lens 14 forms an image at the center of the field lens 14. That is, a secondary light source image of the light emitted from the light source device 10 is formed on the field lens 14. The light passing through the field lens 14 enters the PBS prism 15.

The PBS prism 15 functions as a polarization separation element. The PBS prism 15 has a structure in which two right-angle prisms are bonded to each other. A polarization beam splitter film (hereinafter referred to as a PBS film) 15a is formed on the surface where the two right-angle prisms abut. The PBS film 15a reflects the P-polarized light (first polarized light) L12 of the incident light L11 with respect to the PBS film 15a, and transmits the S-polarized light (second polarized light) L13 of the incident light L11 with respect to the PBS film 15a. It is characteristic.
Hereinafter, the S-polarized light for the PBS film 15a may be simply referred to as S-polarized light, and the P-polarized light for the PBS film 15a may be simply referred to as P-polarized light.

  The PBS prism 15 of the present embodiment is configured such that the normal direction of the surface of the PBS film 15a forms an angle of approximately 45 ° with the illumination optical axis 1A. Of the light L11 incident on the PBS film 15a, the S-polarized light L12 is reflected by the PBS film 15a, the optical axis is bent by approximately 90 °, and is incident on the imaging lens 16. Of the light L11 incident on the PBS film 15a, the P-polarized light L13 passes through the PBS film 15a and is removed from the illumination optical system.

  The S-polarized light L12 incident on the imaging lens 16 is collimated by the imaging lens 16 and illuminates the liquid crystal light valve 17. As described above, the illumination optical system of the present embodiment includes the light source device 10, the color wheel 11, the condensing lens 12, the reflection mirror 13, the field lens 14, the PBS prism 15, and the imaging lens 16. This illumination optical system is Koehler illumination.

  In the present embodiment, Koehler illumination is configured such that light emitted from the light source device 10 is relayed as non-parallel light between the condenser lens 12 and the imaging lens 16. This non-parallel light has a cross-sectional area perpendicular to the illumination optical axis 1 </ b> A of the light beam smaller than the area of the illuminated region of the liquid crystal light valve 17.

  As shown in FIG. 3, if a virtual point light source is arranged in the liquid crystal light valve 17, the light L31 emitted from the point light source passes through the imaging lens 16, the PBS prism 15, the field lens 14, and the reflection mirror 13. In this order, an image is formed on the condenser lens 12. That is, the liquid crystal light valve 17 that is the illuminated area of the illumination optical system is conjugate with the exit pupil of the condenser lens 12.

  The liquid crystal light valve 17 functions as a light modulation device that changes the polarization state of incident light. Although the detailed structure of the liquid crystal light valve 17 is not shown, it is, for example, an active matrix reflective liquid crystal panel. The liquid crystal light valve 17 has a liquid crystal layer sandwiched between a pair of electrodes. A reflective portion is provided on the opposite side of the liquid crystal layer from the light incident side. The reflection part is formed by, for example, one of a pair of electrodes made of a light reflecting material such as metal.

  The liquid crystal light valve 17 is electrically connected to a signal source that supplies an image signal. When an image signal is supplied from a signal source, a voltage is applied between the electrodes, and the azimuth angle of the liquid crystal molecules is controlled according to the applied voltage. Thereby, the polarization state of the light incident on the liquid crystal layer can be changed. In addition, the light incident on the liquid crystal layer changes its polarization state, is reflected by the reflecting portion, is folded, and is emitted from the incident side.

  In the present embodiment, image light indicating an image is composed of red light, green light, and blue light. The image signal for one frame supplied to the liquid crystal light valve 17 is serial data in which an image signal for red light, an image signal for green light, and an image signal for blue light are arranged side by side. The three types of color light image signals are supplied to the liquid crystal light valve 17 in synchronization with the rotation of the color wheel 11.

  For example, an image signal for red light is supplied to the liquid crystal light valve 17 during a period in which a red color filter is disposed at a position where the light L11 emitted from the light source device 10 passes through the color wheel 11. When the color filter at the position through which the color wheel 11 rotates and L11 passes changes to a green color filter and a blue color filter, the image signal supplied to the liquid crystal light valve 17 also changes for green light and blue light. Thereby, the red light, the green light, and the blue light constituting the image light indicating the color image are time-divided and emitted from the liquid crystal light light valve 17.

  As shown in FIG. 2, the light L 21 emitted from the liquid crystal light valve 17 enters the imaging lens 16, is collected by the imaging lens 16, and enters the PBS prism 15. Of the light L21 incident on the PBS prism 15, S-polarized light L22 is reflected by the PBS film 15a and removed from the projection optical system. Of the light L21 incident on the PBS prism 15, the P-polarized light L23 passes through the PBS film 15a and travels along the projection optical axis 1B. The P-polarized light L23 has a gradation lower than the light L21 emitted from the liquid crystal light valve 17 by the amount of the S-polarized light L22 to be removed.

  For example, if the liquid crystal layer of the liquid crystal light valve 17 is designed so that the polarization direction of light incident on the liquid crystal layer is rotated by 90 ° when no voltage is applied, most of the light L21 becomes P-polarized when no voltage is applied. Therefore, most of the light L21 is emitted through the PBS film 15a, and light for bright display is obtained when no voltage is applied. Conversely, if the liquid crystal layer of the liquid crystal light valve 17 is designed so as to rotate the polarization direction of the light incident on the liquid crystal layer when a voltage is applied, light for bright display can be obtained when the voltage is applied.

  The P-polarized light L23 emitted from the PBS prism 15 is collected by the imaging lens 16, and forms an intermediate image between the PBS prism 15 and the projection lens group 19. A diaphragm 18 is provided at a position where the intermediate image is formed. The diaphragm 18 is optically equivalent to the field lens 14. Therefore, the way in which the illumination light is kicked (vignetting) in the field lens 14 is equivalent to the way in which the projection light is kicked in the diaphragm 18, and the efficiency of the field lens 14 and the diaphragm 18 can be improved.

  Here, since an optical element is not disposed between the PBS prism 15 and the diaphragm 18, the optical path length along the illumination optical axis 1A between the PBS film 15a and the center of the field lens 14 is equal to the PBS film 15a. And the optical path length along the projection optical axis 1B between the aperture 18 and the aperture 18. In this way, the arrangement position of one of the field lens 14 and the diaphragm 18 is determined, and the arrangement position of the other is determined. Therefore, the design is easy.

  The light that has passed through the diaphragm 18 is enlarged and projected onto a screen by a projection lens group 19. As described above, the red light, the green light, and the blue light constituting the image light indicating the color image are time-divisionally emitted from the liquid crystal light valve 17 and projected onto the screen. The projected image is temporally averaged and visually recognized as an afterimage by switching the image by red light, the image by green light, and the image by blue light at high speed. Thereby, a color projection image is obtained. As described above, the projection optical system according to this embodiment includes the imaging lens 16, the PBS prism 15, the diaphragm 18, and the projection lens group 19.

  In the projector 1 of the first embodiment as described above, the liquid crystal light valve 17 is illuminated by Koehler illumination, and no light source image is formed on the liquid crystal light valve 17. Therefore, the spatial illuminance variation of the light L11 emitted from the light source device 10 is reduced, and the liquid crystal light valve 17 is illuminated with a uniform illuminance distribution. Accordingly, it is possible to omit an illuminance uniformizing element such as a fly-eye lens array that equalizes the illuminance distribution, and the projector 1 can be miniaturized.

  Further, since the imaging lens 16 is a part of the illumination optical system and a part of the projection optical system, the number of lenses can be reduced as compared with the case where the illumination optical system and the projection optical system are configured independently. Can be reduced. Thereby, the projector 1 can be reduced in size and cost. A lens such as a fly-eye lens array is made of glass or the like, and is relatively heavy among the components of the projector. By reducing the number of lenses as described above, the projector can be reduced in weight. For example, the portability of the projector can be improved.

  Of the light L21 emitted from the liquid crystal light valve 17, the P-polarized light L23 transmitted through the PBS film 15a hardly feels a positional shift due to a manufacturing intersection of the PBS prism 15 or the like. No loss of quality. Therefore, it is not necessary to use advanced positioning technology for the arrangement of the PBS prism 15 in the manufacturing process of the projector 1, and the manufacturing cost can be reduced. Therefore, the device cost of the projector 1 can be reduced.

  In addition, the light emitted from the light source device 10 is relayed between the condenser lens 12 and the imaging lens 16 as non-parallel light whose cross-sectional area is smaller than the area of the illuminated region, so that the reflection mirror 13 and PBS prism 15 can be reduced in size.

[Second Embodiment]
Next, a projector according to a second embodiment will be described. The second embodiment is different from the first embodiment in that a polarization conversion element is disposed in an optical path between the light source device and the polarization separation element.

  FIG. 4A is a schematic diagram illustrating a schematic configuration of the projector 2 according to the second embodiment, and FIG. 4B is a schematic diagram illustrating an enlarged polarization conversion element. In FIGS. 4A and 4B, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment. In addition, detailed description of the same components as those in the first embodiment may be omitted.

  As shown in FIG. 4A, in the projector 2, a polarization conversion element 20 is disposed on the optical path between the reflection mirror 13 and the field lens 14. The polarization conversion element 20 aligns the polarization state of incident light. As shown in FIG. 4B, the polarization conversion element 20 includes a PBS film 201, a reflection film 202, and a half phase plate 203.

  The PBS film 201 has the same characteristics as the PBS film 15 a provided in the PBS prism 15. Both the PBS film 201 and the reflection film 202 are arranged so as to form an angle of about 45 ° with respect to the illumination optical axis 1A between the reflection mirror 13 and the field lens 14. The PBS film 201 and the reflective film 202 are arranged side by side in a direction orthogonal to the illumination optical axis 1A. In addition, a ½ phase plate 203 is disposed at a position where light transmitted through the PBS film 201 is incident.

  The light emitted from the light source device 10 is collected by the condenser lens 12 and reflected by the reflection mirror 13 as in the first embodiment. Here, the focal length and arrangement of the condenser lens 12, the arrangement of the reflection mirror 13, and the like are adjusted so that the light L41 reflected by the reflection mirror 13 is condensed on the PBS film 201.

  Of the light L41 incident on the PBS film 201, the S-polarized light L42 is reflected by the PBS film 201, the optical axis is bent by approximately 90 °, and is incident on the reflective film 202. The S-polarized light L42 incident on the reflection film 202 is reflected by the reflection film 202, the optical axis is bent by approximately 90 °, and is emitted in a direction substantially parallel to the illumination optical axis 1A. Of the light L41 incident on the PBS film 201, P-polarized light L43 is transmitted through the PBS film 201 and incident on the half-phase plate 203, and the polarization direction is rotated by approximately 90 ° to become S-polarized light L44. Similarly to the S-polarized light L42, the S-polarized light L44 is emitted in a direction substantially parallel to the illumination optical axis 1A, and enters the field lens 14 together with the S-polarized light L42. The S-polarized light L42 and L44 for the PBS film 201 is S-polarized light for the PBS film 15a of the PBS prism 15. Therefore, most of the S-polarized light L42 and L44 having passed through the field lens 14 is reflected by the PBS film 15a and used as illumination light.

  In the projector 2 of the second embodiment as described above, the polarization state of the light source light emitted from the light source device 10 is adjusted by the polarization conversion element 20, and most of the adjusted light is reflected by the PBS film 15a. . Therefore, most of the light emitted from the light source device 10 can be used as illumination light, and the light use efficiency is increased.

  Further, since the light source light is condensed on the PBS film 201 of the polarization conversion element 20 by the condenser lens 12, there is no loss of light due to the direct incidence of light on the reflective film 202 without passing through the PBS film 201. Use efficiency is increased. Further, since the condensed light is incident on the polarization conversion element 20, the polarization conversion element 20 can be reduced in size, and the projector 2 can be reduced in size.

  As described above, the projector of the present invention can significantly reduce the size, weight, and cost of the device. By applying the present invention, a portable projector can be configured. As an example of the use of a portable projector, there can be considered an application for enlarging and projecting a display of a portable electronic device such as a mobile phone, a personal digital assistant (PDA), or a notebook computer. In general, a portable electronic device has a display unit that is smaller than a stationary electronic device due to downsizing, and the display is difficult to see. By integrating such an electronic device with a miniaturized projector or connecting it to a miniaturized projector, an easy-to-see display on a large screen can be easily obtained. In addition, since both the electronic device and the projector are portable, a large screen display can be obtained regardless of the location.

  In the first and second embodiments, the illumination optical system including the color wheel 11 is used to form the single-plate projector 1 that projects a color image by the field sequential method. A single-plate color projector may be configured by a sequential method or a color filter method. For example, a light source device may be configured by a plurality of LEDs that emit color lights having different wavelengths, and a light source device in which the wavelength changes temporally by switching and lighting the plurality of LEDs temporally. . Further, the present invention can be applied to a three-plate type color projector or a single-plate type projector that projects a single color image. Further, as the polarization separation element, a wire grid polarization element or the like may be used instead of the PBS prism 15.

  In the second embodiment, the polarization conversion element 20 is disposed between the reflection mirror 13 and the field lens 14, but may be disposed at another position. If a polarization conversion element is arranged in the optical path between the light source device 10 and the PBS film 15a, light that is not used as illumination is reduced by transmitting through the PBS film 15a, and the effect of increasing the light utilization efficiency is obtained. .

It is a schematic diagram which shows schematic structure of the projector of 1st Embodiment. It is a schematic diagram which shows schematic structure of the projector of 1st Embodiment. It is a schematic diagram which shows schematic structure of the projector of 1st Embodiment. (A) is a schematic block diagram of 2nd Embodiment, (b) is an enlarged view of a polarization conversion element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Projector, 10 ... Light source device, 12 ... Condensing lens, 14 ... Field lens, 15 ... PBS prism (polarization separation element), 16 ... Imaging lens, 17 ... reflective liquid crystal light valve (light modulation device), 18 ... stop, 20 ... polarization conversion element

Claims (5)

A light source device for emitting light;
A polarization separation element that reflects the first polarized light of the light emitted from the light source device and transmits the second polarized light having a polarization direction different from the first polarized light;
A light modulation device that is disposed at a position where the first polarized light reflected by the polarization separating element is incident, modulates the first polarized light, and reflects the reflected light to the polarized light separating element;
A condenser lens disposed in an optical path between the light source device and the polarization separation element;
A field lens disposed in an optical path between the condenser lens and the polarization separation element;
An imaging lens disposed in an optical path between the polarization separation element and the light modulation device,
Koehler illumination for illuminating the light modulation device is configured, including the light source device, the condenser lens, the field lens, and the imaging lens.
A projector comprising a projection optical system that includes the imaging lens and that projects light emitted from the light modulation device and transmitted through the polarization separation element.   The projector according to claim 1, wherein the field lens is disposed at a position conjugate with a diaphragm of the projection optical system.   The polarization conversion element for converting the light emitted from the light source device into the first polarized light is disposed in an optical path between the light source device and the polarization separation element. The projector described.   The projector according to claim 1, wherein the light source device includes a solid light source.   5. The projector according to claim 1, wherein the Koehler illumination illuminates the light modulation device with light whose wavelength changes with time.

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