JP5315809B2 - Projector device - Google Patents

Description

  The present invention relates to a projector device.

In a conventional projector device, light source light is separated into two polarized light beams orthogonal to each other by a polarization separation element, and only one of the polarized light beams is used for projection (for example, Patent Document 1). In this case, since only half of the light source light is used for projection, an illuminating device that improves the light source light utilization efficiency has been proposed (for example, Patent Document 2).
JP 2007-72241 A JP 2006-243433 A

  However, when each of the above-described devices is used in a projector device, since the number of parts to be added is large, the entire device becomes large and a cost increase becomes a problem.

The projector device according to claim 1, a light source, an illumination optical system that condenses light from the light source, and light collected by the illumination optical system is incident, and the incident light is converted into two polarized light beams that are orthogonal to each other. A polarized light separating element that emits light after separation, a reflective display element that one of two polarized lights enters, modulates the incident polarized light according to a display image, and emits the polarized light to the polarized light separating element, and a reflective display element A projection optical system for projecting a projection image obtained by analyzing the polarized light modulated by the polarization separation element, and reflecting the other of the two polarization lights to return to the light source via the polarization separation element First reflecting means, and the first reflecting means has reflection characteristics such that the reflected polarized light returns to the center of the light source.
The projector device according to claim 2 is a light source, an illumination optical system that condenses the light of the light source, and light collected by the illumination optical system is incident, and the incident light is converted into two polarized lights orthogonal to each other. A polarized light separating element that emits light after separation, a reflective display element that one of two polarized lights enters, modulates the incident polarized light according to a display image, and emits the polarized light to the polarized light separating element, and a reflective display element A projection optical system for projecting a projection image obtained by analyzing the polarized light modulated by the polarization separation element, and reflecting the other of the two polarization lights to return to the light source via the polarization separation element and a first reflecting means, the first reflecting means, characterized in that reflects light of a specific wavelength.

  ADVANTAGE OF THE INVENTION According to this invention, the utilization efficiency of light source light can be aimed at, suppressing the enlargement and cost increase of an apparatus.

-First embodiment-
Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a projector apparatus according to the present invention. The projector device includes a high-intensity white LED 1, a condenser lens 2, a polarization beam splitter (PBS) 3, a liquid crystal display element 4, a reflection mirror 5, an absorption polarizer 6P, and a projection lens 7. It is housed and integrated. As the liquid crystal display element 4, a reflective liquid crystal panel such as LCOS (Liquid Crystal on Silicon) is used, and either a monochrome type or a color type may be used, but a color type liquid crystal display element is used below. Will be described. The liquid crystal display element 4 forms a projection image in a predetermined image display area 4a of the liquid crystal display element 4 in accordance with a drive signal from a control circuit (not shown) or the like. That is, the image display area 4a is an effective area used for forming a projected image.

  The white LED 1 used here is a phosphor-type LED, and has a blue LED and a YAG (yttrium, aluminum, garnet) phosphor layer disposed on the front surface of the blue LED. doing. When blue component light is emitted from the blue LED, part of the blue component light is absorbed by the phosphor, and yellow component light is generated from the phosphor. White light is realized by mixing the yellow component light and the remaining blue component light.

  Illumination light emitted so as to diverge from the white LED 1 enters the PBS 3 via the condenser lens 2. The condensing lens 2 is a lens that condenses light rays emitted from the white LED 1 so as to be parallel to the optical axis. The illumination light incident on the PBS 3 is separated into a P-polarized component and an S-polarized light by the polarization separation unit 3a of the PBS 3. The P-polarized light passes through the polarization separation unit 3a and is emitted from the upper surface of the PBS 3 to the liquid crystal display element 4. On the other hand, the S-polarized light is reflected by the polarization separation unit 3 a and emitted from the left surface of the PBS 3 to the reflection mirror 5.

  The P-polarized light that has entered the liquid crystal display element 4 from the PBS 3 travels through the liquid crystal layer of the liquid crystal display element 4, is reflected by the reflecting surface of the liquid crystal display element 4, and then travels in the reverse direction through the liquid crystal layer. 4 is output to the polarization beam splitter 3. An image signal is input to the liquid crystal display element 4, and a voltage is applied to each pixel in accordance with the level of the image signal. At that time, the arrangement of the liquid crystal molecules in the liquid crystal layer changes according to the voltage application state, and the liquid crystal layer serves as a phase plate. As a result, the light emitted from the liquid crystal display element 4 to the PBS 3 includes modulated light modulated from P-polarized light to S-polarized light and unmodulated light that remains P-polarized light.

  The P-polarized light that has entered the liquid crystal display element 4 from the PBS 3 travels through the liquid crystal layer of the liquid crystal display element 4, is reflected by the reflecting surface of the liquid crystal display element 4, and then travels in the reverse direction through the liquid crystal layer. 4 is output to the polarization beam splitter 3. An image signal is input to the liquid crystal display element 4, and a voltage is applied to each pixel in accordance with the level of the image signal. At that time, the arrangement of the liquid crystal molecules in the liquid crystal layer changes according to the voltage application state, and the liquid crystal layer serves as a phase plate. As a result, the light emitted from the liquid crystal display element 4 to the PBS 3 includes modulated light modulated from P-polarized light to S-polarized light and unmodulated light that remains P-polarized light.

  As described above, the P-polarized light incident on the liquid crystal display element 4 undergoes a modulation action according to the displayed image. The light emitted from the liquid crystal display element 4 (including P-polarized light and S-polarized light) is incident on the PBS 3 again and is polarized and separated by the polarization separation unit 3a. This polarization separation is also called “analysis”, and the S-polarized light (modulated light) included in the incident light is reflected by the polarization separation unit 3a, passes through the absorption polarizer 6P, and then a screen (not shown) by the projection lens 7. Projected on top.

  On the other hand, the P-polarized light transmitted through the polarization separation unit 3a travels back in the optical path and enters the white LED 1. The P-polarized light is reflected in the white LED 1 and enters the PBS 3 again, or is used for re-excitation of the phosphor of the white LED 1. The P-polarized light and the light generated by re-excitation are used as illumination light for illuminating the liquid crystal display element 4 again.

  The absorption polarizer 6P disposed between the PBS 3 and the projection lens 7 is a polarizer that absorbs P-polarized light contained in incident light. In an actual PBS, P-polarized light and S-polarized light are not completely separated, and the reflected light contains some P-polarized light. Since this P-polarized light causes a reduction in the contrast of the projected image, a polarizer 6P is inserted to absorb the P-polarized light contained in the projected light beam. Although the polarizer 6P is disposed between the PBS 3 and the projection lens 7 here, it may be disposed between the PBS 3 and the reflection mirror 5, or may be disposed on both.

  On the other hand, the S-polarized light incident on the PBS 3 as the illumination light from the condenser lens 2 and reflected by the polarization separation unit 3a and incident on the reflection mirror 5 is reflected by the reflection mirror 5 and travels back in the optical path to be incident on the white LED 1. To do. As in the case of the P-polarized light described above, the S-polarized light is reflected in the white LED 1 and enters the PBS 3 again, or is used for re-excitation of the phosphor of the white LED 1. The light generated by re-excitation is used as illumination light. Further, the S-polarized light re-entering the PBS 3 is reflected by the polarization separation unit 3a and the reflection mirror 5, and then enters the white LED 1 again. While the reflection between the LED 1 and the reflection mirror 5 is repeated, the S-polarized light rotates, and the P-polarized light component passes through the polarization separation unit 3a and enters the liquid crystal display element 4.

  In this way, the S-polarized light that was thrown away without being used for projection is returned to the white LED 1 by the reflection mirror 5, and the polarization rotation effect by reflection and the re-excitation effect by return light are used. This makes it possible to use part of the unnecessary light as illumination light for the liquid crystal display element 4, thereby increasing the utilization efficiency of the light generated by the light source and improving the brightness of the projected image. Further, since the conventional light source is used as it is and only the reflection mirror 5 is added, the use efficiency of the light source light can be improved while suppressing an increase in the size of the projector device.

  Conventionally, since the S-polarized light reflected in the left direction by the polarization separation unit 3a was not used, about 50% of the light generated by the white LED 1 was discarded without being used. By arranging one reflection mirror 5 as shown in FIG. 1, the brightness of the projected image can be improved. FIG. 2 is a diagram illustrating an experiment performed to confirm the improvement in brightness. In the experiment, a plane mirror is used as the reflection mirror 5, and the spectroluminometer 100 is arranged on the side where the liquid crystal display device 4 of FIG. The transmitted light of the separation part 3a was measured.

  FIG. 3 is a diagram illustrating a spectroscopic measurement result of transmitted light. 3, the vertical axis represents the spectral irradiance, the horizontal axis represents the wavelength, the line L11 indicates the measurement result when the reflection mirror 5 is not provided, and the line L12 indicates the measurement result when the reflection mirror 5 is used. Show. As described above, since the white LED 1 is a phosphor-type LED, in any case, a blue component peak generated in the blue LED (a narrow peak in a wavelength region near a wavelength of 450 nm) and a yellow component generated from the YAG phosphor. (A broad peak in the wavelength range near 550 nm) is observed.

  Comparing the lines L11 and L12 in FIG. 3, it can be seen that the peak of the yellow component is larger when the reflection mirror 5 is arranged, and the light from the phosphor is increased. This increase in the amount of light can be considered to be due to the effect that the phosphor is re-excited by the S-polarized light reflected by the reflecting mirror 5 and returned to the white LED. As a result, it was found that the illuminance was improved by about 19% as a result of the experiment.

  Further, in the case of a phosphor type white LED, the phosphor is excited by the light of the blue LED to generate yellow component fluorescence, and pseudo white light is generated. Therefore, as can be seen from FIG. 3, the peak of the blue component is high and the color is bluish white. However, when the reflecting mirror 5 is used, the amount of yellow component light increases, so that in addition to increasing the amount of white light, it is possible to improve the color tone so as to approach a more natural white color.

  In this experiment, since the spectral luminance meter 100 is disposed in front of the white LED 1 on the optical axis, it is difficult to detect the polarization rotation effect due to reflection on the LED chip surface, and the re-excitation effect appears remarkably in FIG. Yes. In this case, the polarization rotation effect can be confirmed by measuring light away from the optical axis.

-Second Embodiment-
A projector apparatus according to a second embodiment of the present invention will be described. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment is different from the first embodiment in that the white LED 1 provided in the projector device shown in FIG.

  FIG. 4A is an enlarged cross-sectional view of the white LED 1. The white LED 1 includes a base member 12, a light emitting diode element (hereinafter referred to as an LED chip) 13, a cover 14, and the like. The LED chip 13 provided on the base member 12 is a white LED in which a light source that is a blue light emitter (LED) is covered with a yellow light emitting phosphor. That is, the blue light emitted from the blue light emitter passes through the yellow light emitting phosphor and is emitted as blue component light, and excites the yellow light emitting phosphor. The excited phosphor emits yellow component light (fluorescence). As a result, white light is emitted from the LED chip 13.

  The cover 14 is formed in a hollow dome shape with a hemispherical surface by a transparent member such as plastic, and is provided on the base member 12 so as to cover the LED chip 13. The cover 14 is disposed so that the center of the hemispherical body and the center of the LED chip 13 substantially coincide. A space S formed between the cover 14 and the base member 12 is filled with a transparent gel-like substance having substantially the same refractive index as that of the cover 12.

  On the outer peripheral surface of the cover 14, a reflective film is provided in a region excluding a predetermined region near the top. That is, the cover 14 is formed with a transmissive portion 14a that transmits the light emitted from the LED chip 13 and a reflective portion 13b that reflects the emitted light. The transmission part 14 a is provided on the top of the cover 14, transmits white light emitted from the LED chip 13, and guides it to the condenser lens 2. As shown in FIG. 4B, the area of the transmission portion 14 a is formed based on the shape of the image display area 4 a of the liquid crystal display element 4. That is, the area of the transmissive part 14a is set as an opening so that the image display area 4a and the irradiation range of the light transmitted through the cover 14 substantially coincide.

  The reflecting portion 14b is provided to return light emitted from the LED chip 13 in the side surface direction, that is, light that does not enter the condenser lens 2 as it is and is not used as illumination light to the light source for reuse. The reflecting portion 14b is formed by evaporating aluminum or the like on the surface of the cover 14, for example. The reflecting portion 14 b is provided on the outer peripheral surface of the hemispherical cover 14, and the center of the cover 14 and the center of the LED chip 13 substantially coincide with each other. Therefore, the light emitted from the LED chip 13 and reflected by the reflecting portion 14b is incident on the LED chip 13 located substantially at the center of the hemisphere. As described above, since the area of the transmissive portion 14a is determined based on the numerical aperture of the condenser lens 2 and the distance between the condenser lens 2 and the LED chip 13, all the light not incident on the condenser lens 2 is obtained. The light is reflected by the reflecting portion 14 b and returned to the LED chip 13.

  Of the light that is reflected by the reflecting portion 14 b and reaches the LED chip 13, the reflected light of the blue component excites the yellow light-emitting phosphor that constitutes the LED chip 13. As described above, the blue component light emitted from the blue light emitter of the LED chip 13 also excites the yellow light-emitting phosphor, and in addition to this, the blue component reflected light is incident, so the amount of light emitted from the yellow light-emitting phosphor increases. To do. In addition, the blue component of the reflected light of the reflecting portion 14b that has not been used for the excitation is incident on the inside of the LED chip 13 and is repeatedly reflected and refracted therein to repeat the LED chip. Inject toward 13 outside. Further, the light of the yellow component among the light reflected by the reflecting portion 14b and reaching the LED chip 13 is repeatedly reflected and refracted inside the LED chip 13, and is emitted toward the outside of the LED chip 13 again.

  As described above, part of the light emitted from the LED chip 13 again passes through the transmission part 14a, and the other light is reflected by the reflection part 14b and returns to the LED chip 13 again. Then, the light returning to the LED chip 13 is emitted from the LED chip 13 again as described above. Therefore, the light emitted toward the side surface of the LED chip 13 can be used as light that passes through the transmission portion 14a. For this reason, the light reflected by the reflecting portion 14b is reused, the amount of light transmitted through the transmitting portion 14a is increased, and this is equivalent to a state where the light collection efficiency of the light emitted from the white LED 1 of the condenser lens 2 is increased. Become.

According to the second embodiment described above, in addition to the functions and effects obtained by the first embodiment, the following functions and effects are obtained.
(1) The reflection part 14b was provided in the cover 14 which comprises white LED1, and the light which does not inject into the condensing lens 2 among the lights inject | emitted from the LED chip 13 was returned to the LED chip 13, and it was made to reuse. That is, the light reflected by the reflecting portion 14 b is incident on the LED chip 13, is repeatedly excited and reflected, and is emitted toward the condenser lens 2. Therefore, like the conventional white LED 11 shown in FIG. 5, the light LA that is not effectively used can be used, which is emitted in the side surface direction of the LED chip 11a. In addition, the amount of emitted light can be increased.

(2) On the outer peripheral surface of the cover 14 of the white LED 1, a transmission part 14 a having a shape corresponding to the image display area 4 a and a reflection part 14 b for reflecting the emitted light are provided. And the reflection part 14b returned the light which is not incident in the image display area 4a to the LED chip 12 among the lights inject | emitted from the LED chip 12, and was made to inject | emits it as the light which goes to the image display area 4a. Accordingly, the entire amount of light that is not guided to the image display area 4a is reflected by the reflecting portion 14b and can be reused, increasing the light use efficiency and increasing the amount of light incident on the condenser lens 2 from the white LED 1. be able to.

The projector apparatus according to the first and second embodiments described above can be modified as follows.
-Modification 1-
Instead of the P-polarized light reflected by the polarization separation unit 3a, S-polarized light can be used for projection. In this case, the projector apparatus has a configuration as shown in FIG. The S-polarized light reflected by the polarization separation unit 3 a enters the liquid crystal display element 4. The projection light that has been modulated by the liquid crystal display element 4 to become P-polarized light passes through the polarization separation unit 3a and the polarizer 6S that absorbs S-polarized light, and is projected onto the screen by the projection lens 7. Thus, in the case of FIG. 6, the P-polarized light in the illumination light is a polarization component that has not been used conventionally, and has the same operational effects as in the case of the S-polarized light in FIG. 1.

-Modification 2-
The reflection mirror 5 is not limited to being provided independently. For example, as shown in FIG. 7, the white LED 1, the condenser lens 2, the PBS 3, the liquid crystal display element 4, the polarizer 6 </ b> P, and the projection lens 7 are integrated in a case 8, and a vapor deposition film is formed on the inner surface of the case 8. By forming, it can be set as the reflective mirror 5. FIG. The distance between the reflecting mirror 5 and the PBS 3 is set to the dimension d described in Modification 3 described later. As described above, in the second modification, the vapor deposition film formed on the inner surface of the case 8 is used as the reflection mirror 5, so that the apparatus can be reduced in size and weight by reducing the number of components.

-Modification 3-
FIG. 8 is a diagram for explaining a third modification. As described above, the condensing lens 2 is an optical system that converts the light from the white LED 1 into parallel light. However, actually, the condenser lens 2 does not become ideal parallel light, and includes a light beam deviating from the parallel light. This is due to the fact that the light source is not an ideal point light source and that it is difficult to use parallel light in order to reduce the size of the projector device. For this reason, a light beam that is emitted obliquely from the condenser lens 2 and incident on the PBS 3 is also generated like the light beam L1.

The light beam L1 is incident on the PBS 3 from the condenser lens 2, but indicates light emitted to the reflection mirror side without entering the polarization separation surface 3a, and passes through the end portion of the PBS 3 to reflect the reflection mirror. It shows the light emitted to the side. At this time, if the distance d between the PBS 3 and the reflecting mirror 5 satisfies the following expression (1), the reflected light beam L1 will not enter the PBS 3 again and adversely affect the projected image. The angle θ is the angle of the light beam L1 with respect to the exit surface of the PBS 3, and a is the length of one side of the PBS 3.
d> (a / 2) · tan θ (1)

  The position of the reflecting mirror 5 shown in FIG. 8 shows the case of d = (a / 2) · tan θ, and the light beam L1 reflected by the reflecting mirror 5 enters the upper end portion of the PBS 3. doing. The light ray L2 shows a case where the distance d is smaller than (a / 2) · tan θ, and is incident on the PBS 3 again to cause a ghost or the like. On the other hand, the light ray L3 shows a case where the distance d is larger than (a / 2) · tan θ, and the light reflected by the reflection mirror 5 does not re-enter the PBS 3.

  Even when the distance d is set as shown in the equation (1), the light leaks to the outside through the gap between the PBS 3 and the reflecting mirror 5 as shown by the light beam L3, and the influence as scattered light appears. Therefore, by providing the light shielding member 10 as shown in FIG. 8, such scattered light can be prevented.

-Modification 4-
FIG. 9 is a diagram showing a fourth modification of the present embodiment. If the light emitted from the condenser lens 2 is completely parallel light, the S-polarized light reflected by the polarization separation unit 3a enters the reflection mirror 5 perpendicularly, and the reflected light travels back in the optical path to the white LED 1. And return. However, as described in FIG. 8, the actual light emitted from the condenser lens 2 is deviated from the parallel light. Therefore, as shown in FIG. 9A, the light beam away from the optical axis is incident on the polarization separation unit 3a at an angle deviated from 45 degrees, is reflected by the polarization separation unit 3a, and enters the reflection mirror 5. S-polarized light is also incident obliquely as the distance from the optical axis increases. As a result, the reflected light is not reflected in a direction reverse to the optical path, and a part of the reflected light does not return to the white LED 1.

  Therefore, in the fourth modification, the reflecting surface of the reflecting mirror 5 has a surface shape having optical power so that S-polarized light that is not parallel light is incident on the reflecting surface of the reflecting mirror 5 perpendicularly. The surface shape of the reflection mirror 5 is set according to the optical characteristics of the condenser lens 2. That is, as shown in FIG. 9A, when the light beam emitted from the condensing lens 2 has a shape that spreads as it travels, the reflection surface shape of the reflection mirror 5 is a concave shape. On the other hand, as shown in FIG. 9B, when the light beam emitted from the condensing lens 2 has a shape that narrows as it travels, the reflection surface shape of the reflection mirror 5 is a convex shape.

  As described above, in the fourth modification, since the reflecting mirror 5 is given power so that the S-polarized light emitted from the PBS 3 is perpendicularly incident on the reflecting mirror 5, the S reflected by the reflecting mirror 5 is provided. All of the polarized light travels back along the optical path and returns to the white LED 1 as the light source. As a result, it is possible to further improve the utilization efficiency of S-polarized light, which has been discarded in the past.

  Here, the optical characteristic (power) of the reflecting mirror 5 is set so that the reflected S-polarized light travels in the reverse direction of the optical path. You may make it give a characteristic. By making the light incident at the center of the light source, the re-emitted light tends to be emitted from the center of the light source. As a result, the light that has passed through the condenser lens 2 that has been re-emitted is turned into light that is closer to parallel light. In particular, for light generated from the phosphor by re-excitation, the effect of collecting the light at the center of the light source is significant. Further, the configuration described in the modification 3 can be similarly applied to the reflection mirror 5 having the power as described above.

-Modification 5-
FIG. 10 is a diagram illustrating a fifth modification of the present embodiment. In the above-described embodiment, the white LED 1 is used as the light source. However, in the modified example 5, as shown in FIG. 10A, three independent LEDs 1R and 1G that generate R light, G light, and B light are used. 1B is used as a light source.

  FIG. 10A shows a case where a plane mirror is used as the reflection mirror 5, and FIG. 10B shows a case where a concave mirror is used as the reflection mirror 5. In any case, R light, G light, and B light emitted from the LEDs 1R, 1G, and 1B are incident on the cross dichroic prism 20 via the condenser lens 2 from three directions. The R light, G light, and B light incident on the cross dichroic prism 20 are respectively emitted upward in the figure and incident on the PBS 3.

  The R light, G light, and B light are separated into S-polarized light and P-polarized light by the PBS 3, each P-polarized light is incident on the liquid crystal display element 4, and each S-polarized light is incident on the reflection mirror 5. . Each of the S-polarized light of R light, G light, and B light is reflected by the reflection mirror 5, travels backward in the optical path, and enters the cross dichroic prism 20. The cross dichroic prism 20 emits the incident S-polarized light of the R light in the LEDIR direction, emits the S-polarized light of the G light in the LEDIG direction, and emits the S-polarized light of the B light in the LEDIB direction. Therefore, similarly to the above-described embodiment, the utilization efficiency of the light source light can be improved, and the brightness of the projected image can be improved.

  In the configuration shown in FIG. 10B, if the optical characteristics of the three condenser lenses 2R, 2G, and 2B are the same, the power of the reflection mirror 5 can be made to correspond to all the condenser lenses 2R, 2G, and 2B. However, if the optical characteristics of the condenser lenses 2R, 2G, and 2B are different, the power of the reflection mirror 5 is set in accordance with the optical characteristics of the condenser lens of the color light whose light quantity is to be increased. For example, the brightness of the projected image can be further improved by combining the power with the G light having the highest specific sensitivity. For the purpose of adjusting the color balance of the projected image, the power may be adjusted to the condensing lens of the color light having the lowest light emission efficiency and the light emission efficiency of the LED.

-Modification 6
FIG. 11 is a diagram illustrating a sixth modification of the present embodiment. In the projector apparatus shown in FIG. 10B described above, the brightness of the projected image is further improved by using three independent LEDs 1R, 1G, and 1B and adjusting the power of the reflecting mirror 5 to which color light. Or adjusting the color balance of the projected image. The projector device of Modification 6 is configured such that the same effect can be obtained even when the white LED 1 is used as shown in FIG.

  In the example shown in FIG. 11A, the same effect as in FIG. 10B is obtained by inserting the color filter 30 between the reflection mirror 5 and the PBS 3. For example, if a color filter that transmits G light is used as the color filter 30, only S-polarized light of G light returns to the white LED 1. improves. On the other hand, when adjusting the color balance, a color filter that transmits a small amount of color light may be used as the color filter 30.

  In the example shown in FIG. 11B, the same effect can be obtained by using a dichroic mirror 40 that reflects only light in a specific wavelength region instead of the reflection mirror 5 and the color filter 30 in FIG. It was set as the structure.

  In the example shown in FIG. 11C, the λ / 4 wavelength plate 50 is arranged between the condenser lens 2 and the PBS 3 in the configuration shown in FIG. The frequency λ of the λ / 4 wavelength plate 50 is set to match the wavelength of the color light reflected by the dichroic mirror 40. For example, when the dichroic mirror 40 is designed to reflect the G light, the S-polarized light of the G light reflected by the dichroic mirror 40 is reflected by the polarization separation unit 3 and then has a λ / 4 wavelength. The plate 50 makes it elliptically polarized light. When the elliptically polarized light of the G light is reflected by the white LED 1 and passes through the λ / 4 wavelength plate 50 again, it becomes P-polarized light rotated by 90 degrees with respect to the S-polarized light.

  As a result, the P-polarized light of the G light is transmitted through the polarization separation unit 3 a of the PBS 3 and enters the liquid crystal display element 4. When the λ / 4 wavelength plate 50 is not used, the amount of light is increased by utilizing the polarization rotation effect due to the reflection of the S-polarized light, so that only a part of the returned S-polarized light returns to the liquid crystal display element 4. Used as illumination light. However, when the λ / 4 wavelength plate 50 is used, the returned S-polarized light is polarized and rotated to P-polarized light by the λ / 4 wavelength plate 50, which is a light source as compared with the case of only polarization rotation by reflection. The light utilization efficiency is further improved. Note that the same effect can be obtained in the case of using the S-polarized light as the polarized light for reading the image of the liquid crystal display element 4.

  In any of the cases shown in FIGS. 11A to 11C, the same effect as in the case of the apparatus shown in FIG. 9 can be obtained by giving power to the reflection mirror 5 or the dichroic mirror 40. Also in the configurations of FIGS. 11A and 11B, the distance between the reflection mirror 5 or the dichroic mirror 40 and the PBS 3 is set to be larger than the above-described distance d in order to suppress the adverse effect of scattered light. Is preferred. Furthermore, you may make it provide the shielding member 10 as shown in FIG.

-Modification 7-
The reflection part 14b of the white LED 1 may be formed of a dichroic mirror that reflects a blue component. Light emitted from the LED chip 13 and reflected by the dichroic mirror and incident on the LED tick 13 can be light of only a blue component. As a result, compared with the case where the reflected light contains yellow component light, the amount of yellow component light in the re-emitted white light is suppressed.

-Modification 8-
In the above-described embodiment, the block-like PBS 3 is used as an optical element that separates two polarized light beams orthogonal to each other. However, a flat plate type optical element such as a wire grid polarizer or a birefringent reflective polarizer is used. It may be used. FIG. 12 shows a configuration using a wire grid polarizer 60, FIG. 12 (a) shows a case where a planar reflection mirror 5 is used, and FIG. 12 (b) shows a case where the reflection mirror 5 having power is used. This is the case.

  It is possible to combine the embodiment described above with one or a plurality of modifications, and it is also possible to combine the modifications. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

The figure which shows one Embodiment of the projector apparatus by this invention Illustration explaining the experiment for confirming the improvement in light intensity Figure showing the measurement result of the spectral luminance meter Sectional drawing explaining the structure of white LED vicinity The figure explaining the structure of the light source vicinity by a prior art The figure which shows the 1st modification The figure which shows the 2nd modification The figure which shows the 3rd modification The figure which shows the 4th modification The figure which shows the 5th modification The figure which shows the 6th modification The figure which shows the 8th modification

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... White LED 1R, 1G, 1B ... LED 2 ... Condensing lens
DESCRIPTION OF SYMBOLS 3 ... Polarization beam splitter (PBS) 3a ... Polarization separation part 4 ... Liquid crystal display element 5 ... Reflection mirror 6P, 6S ... Polarizer 7 ... Projection lens 8 ... Case 10 ... Light shielding member 14 ... Cover 14a ... Transmission part 14b ... Reflection part 20 ... Cross dichroic prism 30 ... Color filter 40 ... Dichroic mirror 50 ... λ / 4 wavelength Plate 60 ... Wire grid polarizer

Claims (13)

A light source;
An illumination optical system for condensing the light of the light source;
A polarized light separating element that receives the light condensed by the illumination optical system, separates the incident light into two polarized light beams orthogonal to each other, and
A reflective display element in which one of the two polarized lights is incident, and the incident polarized light is modulated in accordance with a display image and emitted to the polarization separation element;
A projection optical system for projecting a projection image obtained by analyzing the polarized light modulated by the reflective display element by the polarization separation element;
First reflecting means for reflecting the other of the two polarized lights and returning it to the light source via the polarization separating element;
The projector apparatus according to claim 1, wherein the first reflecting means has a reflection characteristic such that the reflected polarized light returns to the center of the light source. A light source;
An illumination optical system for condensing the light of the light source;
A polarized light separating element that receives the light condensed by the illumination optical system, separates the incident light into two polarized light beams orthogonal to each other, and
A reflective display element in which one of the two polarized lights is incident, and the incident polarized light is modulated in accordance with a display image and emitted to the polarization separation element;
A projection optical system for projecting a projection image obtained by analyzing the polarized light modulated by the reflective display element by the polarization separation element;
First reflecting means for reflecting the other of the two polarized lights and returning it to the light source via the polarization separating element;
The projector device characterized in that the first reflecting means reflects light of a specific wavelength. In the projector apparatus of Claim 1 or 2,
The projector apparatus according to claim 1, wherein the first reflecting means has a reflection characteristic such that the reflected polarized light travels backward in the optical path before reflection. In the projector apparatus as described in any one of Claims 1 thru | or 3,
The distance between the first reflecting means and the polarization separating element is determined so that light that enters the polarization separating element from the light source and is not separated by the polarization separating element but is incident on the first reflecting means is reflected by the light. A projector apparatus characterized in that it is set to be larger than the critical incident interval when reaching the mold display element. The projector device according to claim 4, wherein
Light that is incident on and reflected by the first reflecting means without being separated by the polarization separating element is prevented from traveling outward from the region between the first reflecting means and the polarization separating element. A projector apparatus comprising a shielding member. The projector device according to claim 2,
A projector apparatus, wherein a λ / 4 wavelength plate relating to a wavelength within the specific wavelength range is disposed between the illumination optical system and the polarization separation element. In the projector apparatus as described in any one of Claims 1 thru | or 6,
A polarizer that transmits polarized light having a polarization direction that is the same as the polarized light that is incident on the first reflecting means and that absorbs polarized light that is orthogonal to the incident polarized light, the polarization separation element and the projection optical system, And at least one of the polarization separation element and the first reflecting means. In the projector apparatus as described in any one of Claims 1 thru | or 7,
The projector apparatus, wherein the light source is a phosphor type LED. In the projector apparatus as described in any one of Claims 1 thru | or 8 ,
A projector apparatus, further comprising: a second reflecting unit that reflects light that is not incident on the illumination optical system out of light emitted from the light source and returns the light to the light source. The projector device according to claim 9 , wherein
The projector device characterized in that the second reflecting means has a predetermined curved surface shape. The projector device according to claim 10 , wherein
The projector apparatus according to claim 2, wherein the second reflecting means has a reflection characteristic such that the reflected light returns to the center of the light source. The projector device according to any one of claims 9 to 11 ,
The second reflecting means includes an opening formed in a shape corresponding to an effective area of the reflective display element,
A projector apparatus that reflects light that is not incident on the effective area and returns the light to the light source, and causes the light returned to the light source to enter the effective area. The projector device according to any one of claims 9 to 12 ,
The projector device, wherein the second reflecting means reflects light in a specific wavelength range.

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