JP2015184303A - Light source optical device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source optical device and a projector 10 where light efficiency of light source light is enhanced.SOLUTION: A light source optical device includes: a light source; an illumination optical system 110 including a plurality of lenses for refracting light irradiated from the light source; and a TIR prism 120 for refracting and transmitting light source light through the illumination optical system 110. In the light source optical device, an optical axis of a lens 119 located at the forefront among the plurality of lenses in the illumination optical system 110 is deviated from an axis of the other lenses.

Description

  The present invention relates to a light source optical device that irradiates a display element with light source light using a TIR prism, and a projector including the light source optical device.

  2. Description of the Related Art Today, data projectors are widely used as image projection apparatuses that project a screen of a personal computer, a video image, an image based on image data stored in a memory card or the like onto a screen. Conventionally, projectors using a high-intensity discharge lamp as the light source have been the mainstream. However, in recent years, there have been proposals for projectors that use laser diodes with low power consumption, long life, and high luminance.

  In order to promote the reduction in size and weight of the projector and the simplification of the optical system, the TIR prism (total reflection prism) is used when the image light formed by the DMD (digital micromirror device) is incident on the projection lens that is the projection optical system. It has also been proposed to use (for example, Patent Document 1 and Patent Document 2).

JP 2002-156602 A JP 2012-073489 A

  In a projector using a TIR prism, projection image light is formed by a display element such as a DMD, and the direction of the principal ray of the image light emitted from the display element and totally reflected by the TIR prism is determined by the direction of the optical axis of the projection lens. The arrangement of the TIR prism is determined so as to substantially match the above.

However, in the light of each pixel emitted from the display element, not only the light parallel to the chief ray but also the incident angle at the total reflection surface of the TIR prism is reduced from the direction of the chief ray of the reflected light of each micromirror. Even if the incident light at the total reflection surface of the TIR prism is set so that the incident angle exceeds the total reflection critical angle, a part of the light reflected by the micromirror is included. Includes light that does not reach the critical angle, and some light is not totally reflected and does not go to the projection lens.
This has contributed to a decrease in the light utilization rate.

  The present invention has been made in view of the above-described problems of the prior art, and a light source optical device as an optical system for improving the light use efficiency of a light source in a projector using a TIR prism, and a projector including the light source optical device. The purpose is to provide.

  The light source optical device of the present invention includes a light source, an illumination optical system composed of a plurality of lenses that refract light emitted from the light source, and a TIR prism that refracts and transmits light source light that passes through the illumination optical system. The optical axis of the lens located in the forefront among the plurality of lenses is deviated from the optical axes of the other lenses.

  The projector of the present invention includes the above-described light source optical device, a display element that generates projection light when irradiated with light emitted from the light source optical device, and the TIR prism of the light source optical device that is formed of the display element. And a projector control means for controlling the display element and the light source optical device.

  According to the present invention, it is possible to provide a light source optical device having a high light utilization rate and a small projector including the light source optical device.

1 is an external perspective view showing a projector according to an embodiment of the invention. It is a figure which shows the functional block of the projector which concerns on embodiment of this invention. 1 is a schematic plan view showing an internal structure of a projector according to an embodiment of the invention. It is a cross-sectional schematic diagram which shows a mode that light injects into the microlens array of the projector which concerns on embodiment of this invention, and is radiate | emitted. It is a schematic diagram which shows a mode that light injects into the illumination optical system and TIR prism which concern on embodiment of this invention, and is radiate | emitted. It is a schematic diagram which shows the optical axis state and total reflection critical angle by the illumination optical system and TIR prism which concern on embodiment of this invention. As a comparative example, it is a schematic diagram showing an optical axis state and a total reflection critical angle by an illumination optical system that is a general illumination optical system with one optical axis and a TIR prism. As another comparative example, it is a schematic plan view showing a case where a two-prism including a main prism and an incident prism is used as a TIR prism in a system in which optical axes are matched. It is a plane schematic diagram which shows the modification of the TIR prism which concerns on embodiment of this invention. It is a plane schematic diagram which shows the case where the foremost concave lens is shifted as a modification to embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external perspective view of the projector 10. In the present embodiment, left and right in the projector 10 indicate the left and right direction with respect to the projection direction, and front and rear indicate the screen side direction of the projector 10 and the front and rear direction with respect to the traveling direction of the light beam group.

  As shown in FIG. 1, the projector 10 has a substantially rectangular parallelepiped shape, and has a projection portion on the side of a front plate 12 that is a side plate in front of the projector housing. The exhaust hole 17 is provided. Further, although not shown, an IR receiver for receiving a control signal from the remote controller is provided.

  The upper case 11 of the housing is provided with a key / indicator section 37. The key / indicator section 37 is a power switch key, a power indicator for notifying power on / off, and switching on / off of projection. Keys and indicators such as an overheat indicator for notifying when the projection switch key, the light source unit 60, the display element 51, the control circuit, etc. are overheated are arranged. The upper case 11 covers the upper surface and a part of the left side surface of the projector 10 so that the upper case 11 can be detached from the lower case 16 when a failure occurs.

  In addition, an input / output connector is provided on the rear surface of the housing, which is provided with a D-SUB terminal, an S terminal, an RCA terminal, an audio output terminal, etc. for inputting a USB terminal or an analog RGB video signal on a back plate not shown. And various terminals such as a power adapter plug are provided. In addition, a plurality of intake holes are formed in the back plate.

  Next, projector control means of the projector 10 will be described with reference to the functional block diagram of FIG. The projector control means includes a control unit 38, an input / output interface 22, an image conversion unit 23, a display encoder 24, a display drive unit 26, and the like.

  The control unit 38 controls the operation of each circuit in the projector 10, and includes a CPU, a ROM that stores operation programs such as various settings fixedly, and a RAM that is used as a work memory. Yes.

  Then, the image signals of various standards input from the input / output connector unit 21 by the projector control means are in a predetermined format suitable for display by the image conversion unit 23 via the input / output interface 22 and the system bus (SB). After being converted so as to be unified into an image signal, it is output to the display encoder 24.

  The display encoder 24 develops and stores the input image signal in the video RAM 25, generates a video signal from the stored contents of the video RAM 25, and outputs the video signal to the display driving unit 26.

  The display driving unit 26 functions as a display element control unit, and drives the display element 51 that is a spatial light modulation element (SOM) at an appropriate frame rate in accordance with the image signal output from the display encoder 24. Is.

  In the projector 10, the light emitted from the light source unit 60, which is a light source that emits light beams in the red wavelength band, the green wavelength band, and the blue wavelength band in a time-sharing manner, is emitted from the illumination optical system 110 and the TIR prism (total reflection prism). ) By irradiating the display element 51 via 120, an optical image is formed by the reflected light of the display element 51 such as DMD, and the image is projected and displayed on a screen (not shown) via the projection optical system. The movable lens group 235 of the projection optical system is driven by the lens motor 45 for zoom adjustment and focus adjustment.

  The image compression / decompression unit 31 performs a recording process in which the luminance signal and the color difference signal of the image signal are data-compressed by a process such as ADCT and Huffman encoding, and sequentially written in a memory card 32 that is a detachable recording medium. .

  Further, the image compression / decompression unit 31 reads the image data recorded on the memory card 32 in the reproduction mode, decompresses each image data constituting a series of moving images in units of one frame, and converts the image data into an image conversion Based on the image data that is output to the display encoder 24 via the unit 23 and stored in the memory card 32, a process for enabling display of a moving image or the like is performed.

  Then, the operation signal of the key / indicator unit 37 constituted by the main key and the indicator provided on the upper case 11 of the casing is directly sent to the control unit 38, and the key operation signal from the remote controller is received by Ir. The code signal received by the unit 35 and demodulated by the Ir processing unit 36 is output to the control unit 38.

  Note that an audio processing unit 47 is connected to the control unit 38 via a system bus (SB). The sound processing unit 47 includes a sound source circuit such as a PCM sound source, converts the sound data into analog in the projection mode and the playback mode, and drives the speaker 48 to emit loud sounds.

  Further, the control unit 38 controls a light source control circuit 41 as a light source control unit, and the light source control circuit 41 is configured so that light of a predetermined wavelength band required at the time of image generation is emitted from the light source unit 60. The light emission of the green light source device 61, the red light source device 91, and the blue light source device 95 of the light source unit 60 is individually controlled.

  Further, the control unit 38 causes the cooling fan drive control circuit 43 to perform temperature detection using a plurality of temperature sensors provided in the light source unit 60 and the like, and controls the rotation speed of the cooling fan from the result of the temperature detection. Further, the control unit 38 causes the cooling fan drive control circuit 43 to keep the cooling fan rotating even after the projector body is turned off by a timer or the like, or to turn off the projector body depending on the temperature detection result by the temperature sensor. Control is also performed.

  Next, the internal structure of the projector 10 will be described. FIG. 3 is a schematic plan view showing the internal structure of the projector 10. The projector 10 includes a light source unit 60 that serves as a light source at the center, includes an illumination optical system 110 on the left side of the light source unit 60, and further includes a TIR prism 120 and a display element 51 on the left of the illumination optical system 110. The light source optical device includes a unit 60, an illumination optical system 110, and a TIR prism 120, and includes a lens barrel 140 having a projection optical system built in front of the TIR prism 120.

  The projector 10 includes a main control circuit board below the light source unit 60, and a light source control circuit 41, a cooling fan drive control circuit 43, and a drive control circuit for a focus motor and a zoom motor inside the left side plate 14. Various control boards are incorporated.

  The projector 10 includes a cooling fan 55 that cools the display element 51 in the vicinity of the left side plate 14 inside the back plate 13, and the display element 51 by a heat sink 53 disposed inside the back plate 13 and the left side plate 14. Is cooling.

  In addition, the light source unit 60 uses the red laser diode 93 as the red light source device 91 and the blue laser diode 97 as the blue light source device 95 to form light emitting means, and cools the red light source device 91 and the blue light source device 95. A heat sink 83 is provided on the right side plate 15 side of the light source unit 60.

  The light source unit 60 includes a green light source device 61, a red light source device 91, a blue light source device 95, and a dichroic mirror 101. The green light source device 61 is arranged on the optical axis of the light beam emitted from the excitation light irradiation device 63 and the excitation light irradiation device 63 arranged in the vicinity of the back plate 13 in the substantially central portion of the projector 10 housing in the left-right direction. The fluorescent light emitting device 73 disposed in the vicinity of the front plate 12 constitutes a light emitting means, and the blue light source device 95 and the red light source device 91 are disposed at a position slightly to the right of the center of the projector 10 housing. I am going to do it.

  The excitation light irradiating device 63 is disposed between the excitation light source 65 and the back plate 13 as a blue laser diode 66 serving as an excitation light source 65 using a semiconductor light emitting element disposed so that the optical axis is perpendicular to the back plate 13. And a collimator lens 67 in front of the blue laser diode 66.

  The excitation light source 65 is composed of 4 (2 × 2) semiconductor light emitting elements by arranging two sets of blue laser diodes 66, which are semiconductor light emitting elements, arranged in two in the left-right direction. On the optical axis of each blue laser diode 66, a collimator lens 67, which is a condensing lens for converting the emitted light from each blue laser diode 66 into parallel light, is disposed.

  Between the heat sink 81 and the back plate 13, a cooling fan 85, which is a blower fan that sucks outside air as a cooling medium and blows it to the heat sink side, is arranged. The excitation light source 65 is formed by the cooling fan 85 and the heat sink 81. Is cooled.

  Further, the fluorescent light emitting device 73 in the green light source device 61 is arranged in parallel with the front plate 12, that is, a fluorescent wheel 75 arranged so as to be orthogonal to the optical axis of the emitted light from the excitation light irradiation device 63, A wheel motor 77 that rotationally drives the fluorescent wheel 75 and a condenser lens group 79 that collects a group of light beams emitted from the fluorescent wheel 75 toward the back plate 13 are provided. A cooling fan 89 is disposed between the wheel motor 77 and the front plate 12, and the fluorescent wheel 75 is cooled by exhausting air from the exhaust holes 17 of the front plate 12.

  The fluorescent wheel 75 is a disk-shaped metal substrate, and an annular fluorescent light emitting region that emits fluorescent light emitted in the green wavelength band using the light emitted from the excitation light source 65 as excitation light is formed as a recess, and the excitation light. In response, a phosphor layer that emits fluorescence is provided. The surface of the fluorescent wheel 75 including the fluorescent light emitting region on the side of the excitation light source 65 is mirror-processed by silver vapor deposition or the like to form a reflective surface that reflects light, and a green phosphor layer is formed on the reflective surface. It is laid.

  The outgoing light from the excitation light irradiation device 63 irradiated on the green phosphor layer of the fluorescent wheel 75 excites the green phosphor in the green phosphor layer. Then, a group of light beams emitted from the green phosphor in all directions is directly emitted to the excitation light source 65 side or reflected by the reflection surface of the fluorescent wheel 75 and then emitted to the excitation light source 65 side.

  Moreover, the excitation light irradiated to the metal substrate without being absorbed by the phosphor of the phosphor layer is reflected by the reflecting surface and is incident on the phosphor layer again to excite the phosphor. Therefore, by using the surface of the concave portion of the fluorescent wheel 75 as a reflective surface, the utilization efficiency of the excitation light emitted from the excitation light source 65 for green wavelength band light can be increased, and light can be emitted more brightly.

  The red light source device 91 and the blue light source device 95 are arranged so that the optical axis of the emitted light and the optical axis of the light from the excitation light source 65 are orthogonal, that is, the fluorescent light emission from the fluorescent light emitting device 73 that is the green light source device 61. A red laser diode 93 and a blue laser diode 97 are arranged side by side so as to be orthogonal to the optical axis of the light. The blue light source device 95 includes a blue laser diode 97 and a collimator lens 98 that collects and emits the light emitted from the blue laser diode 97 into a predetermined range of light. Two blue laser diodes 97 are arranged in the vertical direction.

  On both sides of the blue laser diode 97 before and after, a total of four red laser diodes 93 of the red light source device 91 are arranged, two in the front and rear direction. The red light source device 91 includes a red laser diode 93 and a collimator lens 94 that collects and emits the light emitted from the red laser diode 93 into a predetermined range of light. The red light source device 91 and the blue light source device 95 are arranged so that the emitted light from the excitation light irradiation device 63 and the green wavelength band light emitted from the fluorescent wheel 75 intersect each other.

  The laser light emitted from the red laser diode 93 and the blue laser diode 97 is coherent light whose cross-sectional shape perpendicular to the principal ray is an ellipse. Then, the red laser diode 93 and the blue laser diode 97 are adjusted in the distance from the collimator lens, and the irradiation light to the microlens array 111 of the illumination optical system 110 is condensed and emitted within a predetermined range. Both the red wavelength band light and the blue wavelength band light, which are different wavelength band lights, are emitted in the same direction in close proximity to each other.

  Between the heat sink 83 provided on the right side plate 15 side of the red light source device 91 and the blue light source device 95 and the front plate 12, there is a cooling fan 87 for sucking air warmed by the heat sink 83 and discharging it to the outside of the device. The red laser diode 93 and the blue laser diode 97 are cooled by the cooling fan 87.

  The blue and red wavelength band light is transmitted at a position where the optical axes of the red light source device 91 and the blue light source device 95 and the optical axes of the excitation light irradiation device 63 and the fluorescent light emitting device 73 intersect at right angles. A dichroic mirror 101 that reflects green wavelength band light and converts the optical axis of the green light by 90 degrees toward the left side plate 14 is disposed. Therefore, the light source unit 60 in which each light of red wavelength band light, green wavelength band light and blue wavelength band light is superimposed on the same optical path by one dichroic mirror 101, and each wavelength band light is emitted in a time division manner. Become. Then, the light emitted from the light source unit 60 enters the microlens array 111 of the illumination optical system 110.

  On the left side of the dichroic mirror 101, an illumination optical system 110 including a light guide unit and a plurality of lenses is disposed. The microlens array 111 serving as the light guide means diffuses the light emitted from the light source unit 60 and makes the luminance distribution uniform.

  The microlens array 111 in the present embodiment is an array of microlenses 112 that are convex lenses having a horizontally long rectangular shape in plan view as a lens shape. A plurality of lenses are arranged on the left plate 14 side of the microlens array 111 as illumination optical system lenses. The plurality of lenses collects the diffused uniform light transmitted through the microlens array 111 to the effective size of the display element 51.

  That is, the light source light emitted from the light source unit 60 as a light source is made to have a uniform intensity distribution by the microlens array 111, and the first lens 115 that is a convex lens, the third lens 119, and the second lens 117 that is a concave lens. Through the TIR prism 120.

  The light source light incident on the TIR prism 120 is incident on the display element 51 having a cover glass in the front, and the ON light reflected by the display element 51 is incident on the TIR prism 120 again, and the lens barrel 140 is used as image light. And projected onto the screen by the projection optical system.

  The projection optical system includes a fixed lens group built in the lens barrel 140 and a movable lens group 235 built in the movable barrel, and is a variable focus type lens having a zoom function. By moving the group 235, zoom adjustment and focus adjustment are possible.

  As described above, in the illumination optical system 110, the light source light emitted from the light source unit 60 is incident on each microlens 112 of the microlens array 111 as shown in FIG. 4. The light incident on each microlens 112 is once condensed and becomes diffused light, and a part of the light incident on each microlens 112 is overlapped with each other and is incident on the first lens 115.

  As described above, since part of the light incident on each microlens 112 overlaps each other, even if there is a difference in light density between some of the light beams incident on each microlens 112, this light density Difference, that is, the partial luminance difference is reduced, and the luminance unevenness of the light source light is made uniform.

  Then, as shown in FIG. 5, the light source light collected by the first lens 115 is diffused by the second lens 117 that is a concave lens, further collected by the third lens 119, and incident on the TIR prism 120. .

  This TIR prism 120 is a single prism with a right-angled isosceles triangular prism, and the side surface including the hypotenuse of the column bottom is defined as the hypotenuse surface 123, and one side of the two adjacent sides that are the sides sandwiching the right angle of the column bottom is the neighboring side. The surface 127 is opposed to the display element 51 provided with the cover glass 52, and the other side of the two adjacent side surfaces is set as the adjacent side surface 125 to the entrance of the lens barrel 140 incorporating the projection optical system. Opposed.

  Further, the oblique side surface 123 serving as the incident surface also serves as a total reflection surface for the ON light from the display element 51.

  Therefore, the light source light is made uniform by the microlens array 111 serving as a light guide, and the light source light is condensed by the first lens 115, the second lens 117, and the third lens 119, and the rectangular effective portion range of the display element 51 is collected. In addition, an image in which the incident side surface of each microlens 112 is an object can be superimposed.

  Further, the ON light formed as image light by the display element 51 enters from the adjacent side surface 127 of the TIR prism 120 as shown in FIG. 5, is then reflected by the oblique side surface 123, and enters the lens barrel 140. The light is emitted from the adjacent side surface 125 in the direction in which the light is emitted. Although not shown, the off-light incident on the TIR prism 120 is reflected by the oblique side surface 123 or the adjacent side surface 125 and does not travel toward the entrance of the lens barrel 140.

  As shown in FIG. 5 and the like, in the illumination optical system 110, in the three lenses of the illumination optical system 110, the optical axes of the first lens 115 and the second lens 117 are the same, but the forefront. The optical axis of the third lens 119 is shifted so that it is translated from the positions of the optical axes of the microlens array 111, the first lens 115, and the second lens 117.

  The direction of shifting the third lens 119, which is a convex lens, is such that the oblique side surface 123, which is the incident surface of the light source light, is deviated from the direction of the principal ray in the direction along the oblique side surface 123 of the TIR prism 120. The direction is shifted in a direction away from the illumination optical system 110 (the right side direction in FIG. 5), whereby the light beam transmitted through the second lens 117 and refracted by the third lens 119 is incident on the incident surface of the TIR prism 120. The incident angle to a certain oblique side surface 123 is increased.

The principal ray and the optical path of the ON light in this case, and the optical path of the light beam that becomes the critical angle of the ON light will be described with reference to FIG.
That is, as shown in FIG. 5, in the illumination optical system 110, the entire light beam incident on the first lens 115 via the microlens array 111 is transmitted through the first lens 115 and the second lens 117. Also, the concentration of the light beam group is changed without changing the direction of the principal ray on the optical axis. As shown in FIG. 6, the direction of the light beam is bent when passing through the third lens 119, and the incident angle α <b> 3 when irradiating the oblique side surface 123 of the TIR prism 120 with respect to the on-light principal ray is The refraction angle α1 of the adjacent side surface 127 facing the display element 51 becomes a predetermined angle.

  The angle of refraction α1 from the adjacent side surface 127 is to cause the principal ray of on-light to enter the adjacent side surface 127 perpendicularly when the adjacent side surface 127 of the TIR prism 120 is parallel to the plane of the display element 51. In addition, it is defined as 24 degrees according to the specification of the DMD which is a display element (specification that each micromirror is inclined ± 12 degrees with respect to the DMD surface).

When an optical glass having a refractive index of about 1.59, which is a general value, is used as the TIR prism 120, in order to set the exit angle α1 from the adjacent side surface 127 to 24 degrees, as shown in FIG. The incident angle α3 on the surface 123 is 53 degrees, which is larger than 45 degrees.
Therefore, the shift amount of the optical axis of the third lens 119 from the optical axis of the first lens 115 and the second lens 117 is set according to the relationship with the focal length of the third lens 119 so that the incident angle is obtained. It is determined.

  Thus, if the direction of the principal ray of the on-light emitted from the display element 51 is perpendicular to the adjacent side surface 127 of the TIR prism 120, the principal due to total reflection on the oblique side surface 123, which is a total reflection surface. The change angle of the direction of the light beam is 90 degrees, the direction of the principal light beam is perpendicular to the adjacent side surface 125 of the TIR prism 120, and can enter the lens barrel 140 provided with the projection optical system.

  Therefore, the direction in which the optical axis of the lens barrel 140 containing the projection optical system intersects with the normal of the image forming surface of the display element 51 at 90 degrees and the direction in which the optical axis of the illumination optical system 110 intersects with 90 degrees. The lens barrel 140 can be disposed as follows.

  Since the TIR prism 120 uses optical glass having a refractive index of about 1.59, the critical angle β1 is about 39 degrees, and the ON light is incident on the TIR prism 120 from the adjacent side surface 127. The refraction angle β2 of the ON light at the adjacent side surface 127 is about 6 degrees.

For this reason, in FIG. 6, of the on-light reflected by the respective micromirrors of the display element 51, the light of the on-light component inclined at 6 degrees or more to the right with respect to the normal line of the adjacent side surface 127 is The light leaks to the outside from the TIR prism 120 without being reflected by the hypotenuse surface 123, and all the light that is tilted to the right in FIG. Will be reflected.
In other words, the on-light component light inclined up to 6 degrees to the right with respect to the normal line of the adjacent side surface 127 is totally reflected by the oblique side surface 123 and emitted from the TIR prism 120 to the lens barrel 140 side. Will be. In this case, the refraction angle β3 is about 9.6 degrees.

<First Comparative Example>
In contrast to the present embodiment, in a general optical system (first comparative example) in which the optical axis of the third lens 119 coincides with the optical axis of the first lens 115, as shown in FIG. The principal ray of the light beam that passes through 119 and enters the oblique side surface 123 of the TIR prism 120 has an incident angle α4 on the oblique side surface 123 of 45 degrees, and is incident on the display element 51, that is, refracted from the adjacent side surface 127. In order to set the angle α1 to 24 degrees, the TIR prism 120 uses an optical glass having a refractive index of about 1.46 and a small refractive index.

  Therefore, the critical angle β4 at the TIR prism 120 is about 43 degrees, and the refraction angle β5 of the on light at the adjacent side surface 127 when the on light is incident on the TIR prism 120 from the adjacent side surface 127 is about 2 degrees. It becomes.

Therefore, in the TIR prism 120, the on-light component having an inclination of 2 degrees or more to the right with respect to the normal line of the display element 51 among the on-light reflected by each micromirror of the display element 51 in FIG. Is leaked out of the TIR prism 120 without being reflected by the hypotenuse surface 123.
In other words, only the light of the on-light component inclined up to 2 degrees to the right with respect to the normal line of the adjacent side surface 127 is totally reflected by the oblique side surface 123 and emitted from the TIR prism 120 to the lens barrel 140 side. It will be. In this case, the refraction angle β6 is about 2.8 degrees.

  Thus, when this embodiment is compared with the first comparative example, the value of 2 degrees of β5 in the first comparative example is about 6 degrees of β2 in this embodiment, as shown in FIG. It can be seen that it is easy to be totally reflected.

  When viewed from the lens barrel 140 side, the value of about 2.8 degrees of β6 in the first comparative example is a large value of about 9.6 degrees of β3 in this embodiment, as shown in FIG. Thus, it can be seen that light having a wider angle is incident on the lens barrel 140.

  Thus, by shifting the optical axis of the third lens 119, the incident angle to the TIR prism 120 can be increased, and a prism having a higher refractive index can be used as the TIR prism 120, and the on-light total reflection surface It is possible to reduce leakage from the hypotenuse surface 123.

  Therefore, most of the ON light from the display element 51 can be incident on the projection optical system. By using a prism with a right isosceles triangular prism, the light axis of the projection optical system and the light emitted from the light source unit 60 can be obtained. Adjustment of the angle with the axis and design and adjustment of the fixed angle and fixed position of the TIR prism 120 and the display element 51 can be facilitated.

<Second Comparative Example>
The TIR prism 120 is not limited to the single prism as described above, but a two-prism including the main prism 121 having the total reflection surface and the exit surface 125 and the incident prism 130 is used with a slight gap therebetween. In this case, as shown in FIG. 8, even when the optical axis of the third lens 119 is matched with the optical axis of the first lens 115, the incident angle to the TIR prism 120 can be made larger than 45 degrees.
Accordingly, the refractive index of the TIR prism 120 can be the same as the refractive index of about 1.59, which is a general value, similarly to the case of FIGS. 5 and 6, and the same effect as this embodiment can be obtained. be able to.

  However, in the structure shown in FIG. 8 (second comparative example), it is necessary to use two prisms as the TIR prism, which is disadvantageous in terms of miniaturization and cost. In addition, there are disadvantages that the number of parts is increased and the combination accuracy is required. In addition, when two prisms are used, only the periphery or four corners are often bonded in order to ensure a slight gap between them, and the prism needs to be glued for that purpose. This is also a disadvantage.

  On the other hand, according to the configuration of FIG. 5 and FIG. 6 of the present embodiment, the simple configuration of shifting the optical axis of the third lens eliminates the need to use two prisms as the TIR prism, thereby reducing the size. However, there is a great merit in terms of cost. In addition, there are advantages that the number of parts is reduced and accuracy is not required.

  Also, as shown in FIG. 9, in the present invention, the TIR prism 120 may be a two-prism.

  Also in the TIR prism 120 that is the two-prism, the optical axis of the foremost third lens 119 of the illumination optical system 110 is shifted in the direction in which the incident surface of the incident prism 130 of the TIR prism 120 is away from the illumination optical system 110. Thus, the light source light emitted from the illumination optical system 110 can be bent by the foremost lens and adjusted to increase the incident angle to the incident prism 130, that is, the incident angle to the TIR prism 120.

  Therefore, the TIR prism 120 is made of optical glass having a high refractive index, and the arrangement design of the light source unit 60, the illumination optical system 110, the display element 51, and the projection optical system as a light source is facilitated while increasing the total reflected light amount. This is the same as in the case of FIG. 5 and FIG. 6, but can be designed with a degree of freedom by the refractive index.

  The two prisms of the main prism 121 and the incident prism 130 as the TIR prism 120 are not limited to the use of a right-angled isosceles triangular prism, and an appropriate isosceles triangular prism is used as the main prism 121. The incident prism 130 may also be an appropriate triangular prism.

  However, if a right isosceles triangular prism is used as a single prism or a main prism, the critical angle of incident light on the total reflection surface of the TIR prism 120 using optical glass having a high refractive index is increased, and the image from the display element 51 is increased. Designing and arranging the various optical systems in the projector with the incident angle of light being 45 degrees and total reflection being performed, and the change angle of the principal ray direction due to total reflection of image light being on-light to the projection optical system being 90 degrees Can be easy.

  Further, the light source unit 60 shown in FIG. 3 includes an excitation light source 65, which is a semiconductor light emitting element, and a green light source device 61, which is a phosphor, a red light source device 91, and a blue light source device 95, which is a laser diode (LD) as a semiconductor light emitting element. Are used as a light source of three primary colors, such as a red light emitting diode (LED), a green light emitting diode (LED), a blue light emitting diode (LED), or other semiconductor light emitting elements. A light emitting element that emits a complementary wavelength band light such as a yellow wavelength band light may be added.

  Thus, if a semiconductor light-emitting element is used as a light source, it can be a light source that saves power and has a long life, and if a light source using an excitation light source and a green phosphor is combined, bright three primary colors can be easily obtained. it can. A full-color image can be formed by forming image light of the three primary colors.

Furthermore, instead of the light source unit 60 using a semiconductor light emitting element, a white light source such as a high-pressure discharge lamp and a color wheel may be combined to be a light source that emits at least three primary colors as the same optical axis.
The light source may be a light source device that is, for example, one white light source and used in a black and white projection device. That is, the present invention does not limit the configuration of the light source.

  The illumination optical system 110 shown in FIGS. 3 and 5 and the like includes a microlens array 111 serving as a light guiding unit, and three lenses including two convex lenses and one concave lens as a plurality of lenses. Forming. However, the light guiding means used for making the light source light uniform is not limited to the microlens array 111, but a light tunnel that combines four mirrors to form a hollow quadrangular prism shape, or a solid quadrangular prism shape by optical glass. It is good also as an appropriate light guide means which makes light source light uniform, such as a light guide rod.

  However, if the microlens array 111 is used, it is easy to reduce the size of the light source optical device, and thus it is easy to reduce the size of the projector 10.

  Further, the number of lenses used in the illumination optical system 110 is not limited to three, and an illumination optical system including at least two or more lenses is formed, and among the lenses of the illumination optical system, the foremost lens closest to the TIR prism 120 Is removed from the central axis of the light guide means such as the microlens array 111, so that the light source light emitted from the illumination optical system 110 is refracted by the front-most eccentric lens, and the incident angle to the TIR prism 120 is increased. Anything can be used as long as it is changed.

For example, when the number of lenses of the illumination optical system 110 is three or more and two or more convex lenses and one or a plurality of concave lenses are combined and the concave lens is arranged in the forefront, the incident angle to the TIR prism 120 is increased. Therefore, the foremost concave lens 119A is shifted in a direction approaching (approaching) the incident surface of the TIR prism 120.
A configuration example in this case is shown in FIG.

  As described above, when a plurality of lenses are used as the illumination optical system 110, it is possible to form an image so that the light beams made uniform by the light guiding means are efficiently condensed on the display element 51. When combined, the illumination optical system 110 can be effectively condensed while being small and light.

  And the illumination optical system 110 which arrange | positions one concave lens in the middle of two convex lenses suppresses generation | occurrence | production of an aberration, when condensing the light beam radiate | emitted from the light guide means on the display element 51 efficiently. Illumination light with good utilization efficiency can be given to the display element 51 to generate good image light.

  In the above embodiment, each lens as a plurality of lenses of the illumination optical system 110 has been described as a single lens in the drawing. However, each lens has a plurality of lenses attached to each other. It goes without saying that even a compound lens is equivalent to each lens in the present invention as long as it can be handled as a single lens (unit).

  As described above, the illumination optical system 110 uniformizes the luminance of the light source light from the light source unit 60 that emits the light wavelength groups of the red wavelength band light, the green wavelength band light, and the blue wavelength band light in a time division manner. The projector 10 including the light source optical device that irradiates the display element 51 by refracting the optical axis with the frontmost lens on the output side 110 and then refracting and transmitting the light through the TIR prism 120 is reduced in size and uses light. It can be set as the projector 10 with high efficiency and a bright image projection.

  The embodiment described above is presented as an example, and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

The invention described in the first claim of the present application will be appended below.
[1] a light source;
An illumination optical system composed of a plurality of lenses that refract light emitted from the light source;
A TIR prism that refracts and transmits light from the illumination optical system;
With
A light source optical device, wherein an optical axis of a lens positioned at the forefront among the plurality of lenses is shifted from an optical axis of another lens.
[2] The optical axis of the lens located in the forefront among the plurality of lenses is shifted so that the incident angle of the light emitted from the illumination optical system to the TIR prism is increased. The light source optical device according to [1].
[3] The light source optical device according to [1] or [2], wherein the plurality of lenses include two convex lenses.
[4] The light source optical system according to [3], wherein the plurality of lenses include three lenses: two convex lenses and a concave lens disposed between the two convex lenses. apparatus.
[5] The light source according to any one of [1] to [4], wherein the frontmost lens is a convex lens and is shifted in a direction away from an incident surface of the TIR prism. Optical device.
[6] The light source according to any one of [1] to [4], wherein the frontmost lens is a concave lens and is shifted in a direction approaching an incident surface of the TIR prism. Optical device.
[7] Any one of [1] to [6], further comprising light guide means for uniformizing light emitted from the light source between the light source and the plurality of lenses. The light source optical device according to 1.
[8] The light source optical device according to [7], wherein the light guiding unit is a microlens array.
[9] The light source optical device according to any one of [1] to [8], wherein the TIR prism is a right-angled isosceles triangular prism.
[10] The light source includes a semiconductor light emitting element that emits red wavelength band light, a semiconductor light emitting element that emits green wavelength band light, and a semiconductor light emitting element that emits blue wavelength band light. The light source optical device according to any one of [1] to [9].
[11] The light source includes: a semiconductor light emitting element that emits red wavelength band light; a semiconductor light emitting element that emits blue wavelength band light; and a light emitting unit that emits green wavelength band light from an excitation light source and a green phosphor. The light source optical device according to any one of [1] to [9], including:
[12] The light source optical device according to any one of [1] to [11],
A display element that emits light emitted from the light source optical device to generate projection light;
The projection optical system for projecting image light formed on the display element and emitted through the TIR prism of the light source optical device onto a screen;
Projector control means for controlling the display element and the light source optical device;
A projector characterized by comprising

DESCRIPTION OF SYMBOLS 10 Projector 11 Upper case 12 Front plate 13 Back plate 14 Left side plate 15 Right side plate 16 Lower case 17 Exhaust hole 21 Input / output connector part 22 Input / output interface 23 Image conversion part 24 Display encoder 25 Video RAM 26 Display drive part 31 Image compression / Expansion unit 32 Memory card 35 Reception unit 36 Processing unit 37 Key / indicator unit 38 Control unit 41 Light source control circuit 43 Cooling fan drive control circuit 45 Lens motor 47 Audio processing unit 48 Speaker 51 Display element 52 Cover glass 53 Heat sink 55 Cooling fan 60 Light source unit 61 Green light source device 63 Excitation light irradiation device 65 Excitation light source 66 Blue laser diode 67 Collimator lens 73 Fluorescent light emitting device 75 Fluorescent wheel 77 Wheel motor 79 Condensing lens group 81, 83 Heat sink 85, 87, 89 Cooling fan 91 Red light source device 93 Red laser diode 94 Collimator lens 95 Blue light source device 97 Blue laser diode 98 Collimator lens 101 Dichroic mirror 111 Micro lens array 112 Micro lens 110 Illumination optical system 115 First lens 117 First Two lenses 119 Third lens 119A Concave lens 120 TIR prism 121 Main prism 123 Oblique side surface 125 Adjacent side surface 127 Adjacent side surface 130 Incident prism 140 Lens barrel 235 Movable lens group

Claims (12)

A light source;
An illumination optical system composed of a plurality of lenses that refract light emitted from the light source;
A TIR prism that refracts and transmits light from the illumination optical system;
With
A light source optical device, wherein an optical axis of a lens positioned at the forefront among the plurality of lenses is shifted from an optical axis of another lens.   2. The optical axis of a lens located at the forefront of the plurality of lenses is shifted so that an incident angle of light emitted from the illumination optical system to a TIR prism is increased. The light source optical device according to 1.   The light source optical apparatus according to claim 1, wherein the plurality of lenses include two convex lenses.   4. The light source optical device according to claim 3, wherein the plurality of lenses include three lenses, which are two convex lenses and a concave lens disposed between the two convex lenses.   5. The light source optical device according to claim 1, wherein the frontmost lens is a convex lens and is shifted in a direction away from an incident surface of the TIR prism.   5. The light source optical device according to claim 1, wherein the frontmost lens is a concave lens, and is shifted in a direction approaching an incident surface of the TIR prism.   The light source optics according to any one of claims 1 to 6, further comprising light guide means for uniformizing light emitted from the light source between the light source and the plurality of lenses. apparatus.   The light source optical device according to claim 7, wherein the light guide means is a microlens array.   The light source optical device according to claim 1, wherein the TIR prism is a right-angled isosceles triangular prism.   The light source includes a semiconductor light emitting element that emits red wavelength band light, a semiconductor light emitting element that emits green wavelength band light, and a semiconductor light emitting element that emits blue wavelength band light. The light source optical device according to claim 9.   The light source includes a semiconductor light emitting element that emits red wavelength band light, a semiconductor light emitting element that emits blue wavelength band light, and a light emitting unit that emits green wavelength band light from an excitation light source and a green phosphor. The light source optical device according to claim 1, wherein the light source optical device is a light source optical device. A light source optical device according to any one of claims 1 to 11,
A display element that emits light emitted from the light source optical device to generate projection light;
The projection optical system for projecting image light formed on the display element and emitted through the TIR prism of the light source optical device onto a screen;
Projector control means for controlling the display element and the light source optical device;
A projector characterized by comprising

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