JP6493721B2 - Light source optical device and projector - Google Patents

Description

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

  2. Description of the Related Art Today, data projectors as image projection devices for projecting personal computer screens, video images, and images based on image data stored in a memory card or the like onto a screen are also frequently used in conferences and the like. ing. In such projectors, image projection in a bright room is required with good portability. Conventionally, projectors using a high-intensity discharge lamp as the light source have been mainstream, but in recent years, power saving, long life, Projectors using high-intensity laser diodes have been proposed.

  In order to promote the reduction in size and weight of the projector and the simplification of the optical system, when irradiating the light source light to a display element such as a DMD (digital micromirror device), the light source light is made uniform using a microlens array and an illumination lens. The present applicant has proposed to irradiate the display element by making it (for example, Patent Document 1).

  In addition, an improvement proposal has been made on a projector that uses a microlens array and an illumination lens to increase the uniformity of light source light and the utilization factor of light (for example, Patent Document 2).

JP2013-190591A Japanese Patent Laid-Open No. 10-254059

  As described above, in the projector that irradiates the display element with the light source light by the optical system using the microlens array, the arrangement of each element of the light source optical system and the downsizing of the projector can be facilitated.

  In addition, projectors using high-intensity semiconductor light sources are capable of projecting bright images. However, in order to increase light utilization efficiency and project brighter and clearer images even in a bright room, There is a demand to further increase the efficiency of use.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a light source optical device including an optical system that improves the light utilization efficiency of a light source, and a projector including the light source optical device. And

The light source optical device of the present invention includes a light source, a microlens array that uniformizes light emitted from the light source, an illumination optical system that refracts light transmitted through the microlens array, and an output from the illumination optical system. The illumination optical system includes three lenses in which one concave lens is disposed between two convex lenses, and the micro lens among the three lenses is provided. The lens farthest from the lens array is characterized in that the optical axis is shifted so that the incident angle of the light emitted from the illumination optical system to the total reflection surface of the TIR prism is increased.
The light source optical device of the present invention includes a light source, a microlens array that uniformizes the light emitted from the light source, an illumination optical system that refracts light transmitted through the microlens array, and the illumination optical system. an incident prism that of the outgoing light is incident, and a TIR prisms that light emitted from the incident prism is incident, said illumination optical system includes a single concave lens between two convex lenses are arranged The incident prism includes three lenses, and is arranged in such a direction that an incident angle of light emitted from the illumination optical system to a total reflection surface of the TIR prism is increased.

  The projector according to the present invention includes the above-described light source optical device, a display element that emits light emitted from the light source optical device to generate projection light, and projection optical that projects image light formed by the display element onto a screen. And a projector control means for controlling the display element and the light source optical device.

  The light source optical device according to the present invention can be a light source optical device with high light utilization efficiency, and can be a small projector having an optical system with a high light utilization factor and capable of projecting a bright image.

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 explanatory drawing which shows the state of the light ray which permeate | transmits the micro lens array of the projector which concerns on embodiment of this invention. It is a schematic diagram which shows the conjugate image of the light ray which permeate | transmits the micro lens array of the projector which concerns on embodiment of this invention. It is a schematic diagram which shows the state in which light source light injects into a display element via a TIR prism, and is made to radiate | emit from a display element by the illumination optical system which concerns on embodiment of this invention. As a comparative example, it is a schematic diagram showing a state in which light source light is incident on a display element via a TIR prism and emitted from the display element by two convex lenses that are general illumination optical systems. It is a schematic diagram which shows the permeation | transmission state of the light ray which permeate | transmits the micro lens of the projector which concerns on embodiment of this invention. It is a schematic plan view showing another embodiment of a projector according to an embodiment of the present invention. It is a schematic diagram which shows the principal part in other embodiment of the projector which concerns on embodiment of this invention. It is a schematic diagram which shows the principal part in other embodiment of the projector which concerns on embodiment of this invention. It is a ray tracing diagram showing a state in which light source light is incident on a display element via a TIR prism and emitted from the display element by the illumination optical system according to the embodiment of the present invention. As a comparative example, it is a ray tracing diagram showing a state in which light source light is incident on a display element via a TIR prism and emitted from the display element by two convex lenses that are general illumination optical systems.

  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 used as the illumination optical system 110 and the TIR prism (total reflection). By irradiating the display element 51 via the prism 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 unit 60 and the illumination optical system 110 form a light source optical device.

  The light source light emitted from the light source optical device is irradiated onto the display element 51 through the TIR prism 120, and the projection optical system in which the image light is disposed in front of the TIR prism 120 by the TIR prism 120 is incorporated. The light is incident on the entrance of the lens barrel 140.

  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 disposed in the vicinity of the back plate 13 on an excitation light irradiating device 63 disposed at a substantially central portion in the left-right direction of the projector 10 housing and on a group of light beams emitted from the excitation light irradiating device 63. The fluorescent light emitting device 73 constitutes a light emitting means, and the blue light source device 95 and the red light source device 91 are arranged at a position slightly to the right of the center of the housing of the projector 10.

  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 the left-right direction at the top and bottom, 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 light axis from the excitation light irradiation device 63 and the green wavelength band light emitted from the fluorescent wheel 75 intersect the optical axis.

  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 optical axis 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 red wavelength band light and the blue wavelength band light emitted from the red light source device 91 and the blue light source device 95 and the blue wavelength band light emitted from the excitation light irradiation device 63 and the fluorescent light emitting device 73 are emitted. In the position where the optical axis of the green wavelength band light intersects at right angles, the blue and red wavelength band light is transmitted, the green wavelength band light is reflected, and the optical axis of this green light is 90 degrees toward the left side plate 14. A dichroic mirror 101 that performs degree conversion is disposed.

  Therefore, a single dichroic mirror 101 causes the red wavelength band light, the green wavelength band light, and the blue wavelength band light to overlap each other in the same optical path to obtain a high-intensity light source light. The light can be emitted from the light source unit 60 as a light source by the division and can enter 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 microlens array 111 serving as a light guiding unit and three lenses is disposed. The microlens array 111 diffuses the light emitted from the light source unit 60 and makes the luminance distribution uniform.

  The microlens 112 of the microlens array 111 in the present embodiment is similar in shape to the display element 51 as a horizontally long rectangular shape in plan view, and each microlens 112 has the same size and has an entrance surface and an exit surface. Biconvex lenses having the same curvature are arranged in a lattice pattern. Then, on the left side plate 14 side of the microlens array 111, three lenses are arranged as illumination lenses. The three lenses condense 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.

  In the illumination optical system 110, as shown in FIG. 4, the light source light emitted from the light source unit 60 is incident on each microlens 112 of the microlens array 111, and the light incident on each microlens 112 is emitted. Is incident on the first lens 115.

  In FIG. 4, the mth microlens from the nth microlens 112n, which is the last (lower end not shown) of the microlens array 111 in which n microlenses 112 are arranged in a row (vertical direction in the figure). 112n−m and five microlenses 112n−m + 1, 112n−m + 2, 112n−m + 3, and 112n−m + 4 including the mth microlens 112m are illustrated.

  As described above, the light incident on each microlens 112 having the same curvature and thickness of the lens surface and having the same optical characteristics is emitted and then incident on the first lens 115.

  Further, by making each microlens 112 a biconvex lens, transmitted light in the same state is formed by each microlens 112. The focal points of the biconvex lenses are in the vicinity of each other, and the light ray group that hits the entrance side cell of the microlens 112n-m + 1 is other than the exit side cell of the microlens 112n-m + 1, that is, for example, the microlens 112n-m or the microlens 112n- The light is condensed by the vicinity of the optical axis of the exit side convex lens surface of the microlens 112n-m + 1 so as not to face the exit side lens surface of m + 2. As shown in FIGS. 5 and 6, the conjugate surface 113 of the incident side microlens cell surface of the microlens 112n-m + 1 becomes far away by the exit convex lens surface of the microlens 112n-m + 1.

  In the microlens array 112 in the microlens array 111 in which the microlenses 112 are arranged in a plurality of rows and columns, for example, the mth from the end in the middle from the first microlens 1121 to the last microlens 112n. The light transmitted through the microlenses 112n-m and the mth through fifth microlenses 112n-m + 4 are refracted at the incident surface of each microlens 112 as shown in FIG. The light enters the lens 115 and exits as shown in FIG. 5 and then enters the first lens 115.

  For this reason, each incident side microlens cell surface and its virtual image in the light ray group transmitted through the microlens array 111 and incident on the first lens 115 can be substantially equivalent as shown in FIG. The difference between the ridge line light X1 from one ridge line X1 by the th micro lens 1121 and the ridge line light Xn from the last n th micro lens 112n is the actual size of the first micro lens 1121 and the n th micro lens 112n in the micro lens array 111. And the difference between the ridge line light Y1 from the first microlens 1121 and the ridge line light Yn from the nth microlens 112n in the other ridgeline light is also the same as the actual size difference in the microlens array 111. The imaginary axis of each incident side microlens optical axis by the 112 exit side microlenses Point M1, ··, Mn-m, Mn-m + 1, ··, Mn-m + 4, ··, Mn also, the combined displacement to the displacement of the full scale magnitude of the microlenses 112. Since the virtual image of the conjugate surface 113 is far away, it becomes very large and the deviation can be ignored. The brightness distribution of the superimposed virtual image is an enlarged and superimposed irradiation distribution of the incident side cell of each microlens, Almost uniform.

  Therefore, the light beam transmitted through each micro lens 112 is irradiated onto the display element 51 by the three illumination lenses, and a light source image is formed on the image forming surface of the display element 51 to form a virtual image overlapping on the conjugate plane 113. In some cases, the irradiation light can be effectively uniform in illuminance.

  Since the conjugate surface 113 that is a distant virtual image is irradiated in such a manner as to form an image on the DMD, the illumination optical system 110 using the combined lens formed by the first lens 115, the second lens 117, and the third lens 119 is used. The illumination lens may be configured so as to form an image on the DMD by taking a certain amount of space (that is, back focus) that allows a prism or mirror to be installed up to the DMD, as if it were far away.

  When a general projection lens is used for the lens barrel 140 incorporating the projection optical system, a spherical surface is used in order to reduce the variation due to the position of the display element 51 at the angle formed by the peripheral ray and the principal ray due to the DMD position. In order to reduce aberrations such as aberration, coma aberration, astigmatism, curvature of field, etc., and form a rectangular image, which is the shape of each microlens 112, exactly on the image forming surface of the display element 51. Reduce distortion. An illumination optical system that can easily realize these in a small space has a configuration in which a second lens 117 that is a concave lens is disposed between a first lens 115 that is two convex lenses and a third lens 119.

  FIG. 7 schematically shows a ray tracing diagram in which light source light is incident on the display element via the TIR prism and emitted from the display element by the illumination optical system according to the embodiment of the present invention. (An accurate ray tracing diagram is shown in FIG. 13 described later.)

  As shown in FIG. 7, when the display element 51 is irradiated with light source light by the TIR prism 120 through the illumination optical system 110 including the microlens array 111 and the three combined lenses, and the display element 51 forms image light, The image of the incident side cell of each microlens 112 that has a rectangular shape similar to the shape of the display element 51 is displayed as an image with little variation in the angle formed by the principal ray and the peripheral ray depending on the position of the display element 51 and with little distortion. It can be formed on the image forming surface of the element 51.

  Therefore, while superimposing the image of each microlens 112 on the entire image forming surface, a projection image is formed with a high on-light utilization rate in the lens barrel 140 containing the later projection optical system, and the display element 51. It is possible to reduce the useless light that is irradiated to the surroundings.

  Then, bright image light is formed by the efficiently irradiated light source light, and this image light is reflected by the inclined surface 123 which is the total reflection surface of the TIR prism 120 and incident on the lens barrel 140 incorporating the projection optical system. Can enter the mouth.

  As described above, the illumination optical system 110 refracts the light source light by the first lens 115, the second lens 117, and further the third lens 119 and makes it incident on the TIR prism 120.

  The 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 of the two adjacent sides that are the sides sandwiching the right angle of the column bottom is defined as one side. The adjacent side surface 127 is made to face the display element 51 provided with the cover glass 52, and another projection surface of the two adjacent side surfaces is used as the adjacent side surface 125 to incorporate the projection optical system. The lens barrel 140 is made to face the entrance.

  In addition, the inclined surface 123 serving as the incident surface also serves as a total reflection surface with respect to the ON light from the display element 51.

  Therefore, the ON light formed as image light by the display element 51 is incident from the adjacent side surface 127 of the TIR prism 120, reflected by the inclined surface 123, and incident on the lens barrel 140 as shown in FIG. The off-light incident on the TIR prism 120 in a direction is reflected from the inclined surface 123 and is emitted in a direction other than the entrance of the lens barrel 140, although not shown. Is.

  Thus, if the optical axis of the on-light emitted from the display element 51 is perpendicular to the adjacent side surface 127 of the TIR prism 120, the change in the optical axis due to total reflection at the inclined surface 123, which is the total reflection surface. The angle is 90 degrees, the optical axis is perpendicular to the adjacent side surface 125 of the TIR prism 120, and the light is allowed to travel straight without being refracted by the adjacent side surface 125 so as to enter the lens barrel 140 including the projection optical system. it can.

  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 arranged as described above, and the arrangement design of each member in the projector 10 can be facilitated.

  Further, in this light source optical device, the light source light is made uniform by the microlens array 111 and refracted by the first lens 115, the second lens 117, and the third lens 119, and the angle formed between the principal ray and the peripheral ray is the display element 51. It is possible to form an image of the incident side cell of each microlens 112 with little variation in position and little distortion on the image forming surface of the display element 51.

  In contrast to this embodiment, in the conventional illumination optical system in which only two lenses are combined, distortion occurs when the light source image by the microlens array 111 is formed on the display element 51. The light source light irradiated around the image forming surface increases, and the light collection efficiency to the display element 51 decreases.

  In addition, in the incident light to the display element 51, variation due to the position also increases with respect to the angle between the principal ray and the peripheral ray due to aberration.

  FIG. 8 schematically shows a ray tracing diagram in which light source light is incident on a display element via a TIR prism and emitted from the display element by two convex lenses, which are general illumination optical systems, as a comparative example. (An accurate ray tracing diagram is shown in FIG. 14 described later.)

  When the image light emitted from the display element 51 is reflected by the inclined surface 123 of the TIR prism 120 and travels toward the entrance of the lens barrel 140, each ON light beam exceeds the critical angle when entering the inclined surface 123. In some cases, the light component transmitted and refracted through the inclined surface 123 increased. Further, even if the light beam is emitted from the adjacent side surface 125 of the TIR prism, it does not enter the lens barrel 140 containing the projection optical system, or even if it enters, the light component that is not used for forming the projection image due to hitting the built-in absorbing component. Had increased. These increases resulted in darker projected images.

  However, the illumination optical system 110 according to the present embodiment arranges the concave lens as the second lens 117 between the first lens 115 and the third condenser lens 119, so that the microlens is formed on the image forming surface of the display element 51. When imaging the shape on the incident side of 112, aberration and distortion are reduced by cancellation, variation in the angle between the principal ray of each on-light reflected by each micromirror and the peripheral ray is reduced, and image light is reflected on the inclined surface 123. Since a light component that is wasted, such as being refracted when the light is reflected, can be reduced, a bright projection image can be formed.

  In order to reduce aberrations and the like when combining the illumination lenses as described above, it is usually preferable to set the half angle of view of the combined lens to 30 degrees or less.

  Therefore, the microlens 112 in the microlens array 111 has a distance along the optical axis from the end of one surface of each microlens 112 to the point on the optical axis of the other surface, as shown in FIG. where l is the maximum distance from the center of the surface to the end of the effective surface, h, and the refractive index of the lens glass material is n, the light of the microlens 112 emitted from the center of the surface on the exit side The angle intersecting with the axis is set so that θ ′ is 30 degrees or less.

That is, in the relationship between the distance l from the end of one surface, which is substantially the thickness of the microlens 112, to the point on the optical axis of the other surface, and the distance h, which is the size of the aperture of the microlens 112,
l> h√ (4n ² −1) (Formula 1)
To meet.

This is because the angle of the light ray intersecting with the optical axis in the light ray group incident on the first lens 115 of the illumination optical system 110 is the angle θ ′ intersecting with the optical axis of the outgoing light emitted from the microlens 112, and this outgoing angle θ When the maximum of 'is 30 degrees, the incident angle θ of the effective light transmitted through the microlens 112 to the exit surface is the distance h from the center of the entrance surface or the exit surface to the end, and the thickness of the lens. In relation to the distance l along the optical axis from the center of the surface to the end of the other surface,
tan θ = h / l (Formula 2)
It is represented by

Further, the incident angle θ and the exit angle θ ′ on the exit surface are expressed as follows, where n is the refractive index of the glass material of the lens.
n · sin θ = sin θ ′ (Formula 3)
It will be represented by
Furthermore, since θ ′ has a maximum angle of 30 degrees,
0.5> sin θ ′ (Formula 3)
It becomes.

Therefore,
0.5> sin θ ′ = n · sin θ = n · h / √ (h ² + l ² ) (Formula 4)
The relationship between l and h is expressed by (Equation 1). When the lens thickness l is larger than h√ (4n ² −1) in relation to the aperture 2h of the incident surface, each microlens The inclination of the emitted light from 112 from the optical axis can be within 30 degrees.

  Therefore, in the above-described three lens groups, various aberrations and distortions can be reduced, and a rectangular image of each microlens 112 can be formed on the image forming surface of the display element 51.

  In the above-described embodiment, the display element 51 is irradiated with the light source light via the TIR prism 120. However, as shown in FIG. 10, the irradiation mirror 135 is disposed on the optical axis of the illumination optical system 110. The display element 51 is provided along the back plate 13 inside the back plate 113 of the projector 10, and the light source light via the illumination optical system 110 is irradiated to the display element 51 through the condenser lens 137 and the cover glass 52 by the irradiation mirror 135. On-light as image light may be emitted toward the front plate 12 of the projector 10.

  A heat sink 53 and a cooling fan 55 are provided inside the back plate 13 on the back plate 13 side of the display device 51 to cool the display device 51.

  Also in this case, the illumination optical system 110 including the microlens array 111 and the three lenses in which the concave lens is disposed between the two convex lenses overlaps the rectangular image with less aberration and distortion of each microlens 112 and the display element 51. The image can be formed on the image forming surface.

  Therefore, the display element 51 can be irradiated with light through the microlens array 111 without waste, and most of the ON light from the display element 51 can be incident on and emitted from the projection optical system, so that a bright image can be projected. Can do.

  The TIR prism 120 is not limited to the single prism as described above, but includes a main prism 121 having an inclined surface 123 and an adjacent side surface 125 as a total reflection surface, and an incident prism 130 as shown in FIG. Two prisms may be used.

  In this case, a bright image can be formed by increasing the total reflectance of the inclined surface 123 of the image light.

  In addition, as shown in FIG. 12, the third lens 119, which is the foremost condensing lens of the illumination optical system 110, is shifted so that the incident surface of the TIR prism 120 is away from the illumination optical system 110. By shifting the center of the lens 119, the optical axis of the light source light emitted from the illumination optical system 110 may be bent by the foremost lens and adjusted to increase the incident angle to the TIR prism 120. .

  In this case, compared with the case where the center of the third lens 119 is not shifted, the incident angle to the inclined surface 123 of the TIR prism 120 is increased, and the angle change due to transmission refraction at the inclined surface 123 is large, that is, the refractive index is high. By using the optical glass as the TIR prism 120, the amount of refraction at the time of transmitting through the inclined surface 123 is increased, and consequently the critical angle is increased, and the light source unit 60 serving as a light source is increased while increasing the total reflected light amount. In addition, the layout design of the illumination optical system 110, the display element 51, and the projection optical system can be facilitated.

  The number of lenses of the illumination optical system 110 may be four or more including the configuration of the first lens 115, the second lens 117, and the third lens 119.

  As described above, if four or more lenses are used as the illumination optical system 110 as described above, the image of the incident side cell of the microlens 112 by the light beam uniformized by the microlens array 111 is converted into the principal ray and the peripheral ray. The image can be focused on the display element 51 efficiently by forming an image on the image forming surface of the display element 51 with less variation aberration and distortion of the angle formed.

  However, if the combined lens of two convex lenses and one concave lens as described above is used, it is easy to reduce the size of the illumination optical system 110, and the variation and distortion of the angle between the principal ray and the peripheral ray. It can be set as a pair lens with few.

  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 in combination with a semiconductor light emitting device such as a red light emitting diode (LED), a green light emitting diode (LED), a blue light emitting diode (LED), or other than the three primary colors. 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.

  In this way, the light source light from the light source unit 60 that emits each light beam group of the red wavelength band light, the green wavelength band light, and the blue wavelength band light in a time-sharing manner is increased in luminance by the microlens array 111 and the illumination optical system 110. A projector 10 provided with a light source optical device that forms an image on the image forming surface of the display element 51 as an image with uniform aberration and distortion while being uniform, and a projector 10 capable of projecting a bright image with a small size and high light utilization efficiency. can do.

The light source may be, for example, a light source device that is a white light source and is used in a black and white projection device. That is, the present invention does not limit the configuration of the light source.
In the above embodiment, each lens of a plurality of lenses has been described as a single lens. However, even a compound lens in which each lens is bonded can be handled as one lens (unit). Needless to say, it is equivalent to each lens in the present invention.

<Examples and Comparative Examples>
FIG. 13 shows an accurate simulation result of ray tracing according to the configuration of FIG. 7 of the present embodiment. This corresponds to FIG. 7, which is a schematic diagram.
FIG. 14 shows an accurate simulation result of ray tracing by the configuration of FIG. 8 as a comparative example. This corresponds to FIG. 8, which is a schematic diagram.
In FIGS. 13 and 14, light rays in the depth direction (direction perpendicular to the paper surface) are also superimposed on the paper surface.

In FIG. 14, light that is not totally reflected by the TIR prism is considerably generated as stray light, but in FIG. 13, this stray light is reduced.
Further, in FIG. 14, even if it exits from the adjacent side surface 125 of the TIR prism, it does not enter the lens barrel 140 containing the projection optical system, or even if it enters, it hits the built-in absorbing component to form a projection image. Although light components that are no longer used have increased, such light components are reduced in FIG.
Therefore, it can be seen that the configuration of FIG. 7 has high light utilization efficiency and enables bright 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;
A microlens array for uniformizing the light emitted from the light source;
An illumination optical system that refracts light transmitted through the microlens array;
With
The illumination optical system includes a light source optical device including three lenses in which one concave lens is disposed between two convex lenses.
[2] Each microlens of the microlens array is a convex lens in which the focal point of the incident surface and the focal point of the emission surface are in the vicinity of the emission surface and the vicinity of the incident surface, respectively. Light source optical device.
[3] In each microlens, a distance along the optical axis from the effective portion end of the incident surface to the point on the optical axis of the output surface is set to l, and the effective portion end of the incident surface from the point on the optical axis of the incident surface. When the maximum distance to the part is h and the refractive index of the glass material is n,
l> h√ (4n ² −1) (Formula 1)
The light source optical device according to [2], wherein:
[4] The light source optical device according to any one of [1] to [3], wherein each of the microlenses of the microlens array has a shape similar to a rectangle of the display element.
[5] The light source according to any one of [1] to [4], wherein a lens farthest from the microlens array among the three lenses has an optical axis shifted. Optical device.
[6] 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 [5].
[7] 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 [5], including:
The light source optical device according to any one of the above.
[8] The light source optical device according to any one of [1] to [7],
A display element that emits light emitted from the light source optical device to generate projection light;
A projection optical system that projects image light formed by the display element onto a screen;
Projector control means for controlling the display element and the light source optical device;
A projector 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 110 Illumination optical system 101 Dichroic mirror 111 Micro lens array 112 Micro lens 112a Cell surface 113 Conjugate surface 115 First lens 117 Second lens 119 Third lens 120 TIR prism 121 Main prism 123 Inclined surface 125 Adjacent surface 127 Adjacent surface 129 Absorbing plate 130 Incident prism 135 Irradiation mirror 137 Condenser lens 140 Lens barrel 235 Movable lens group

Claims (8)

A light source;
A microlens array for uniformizing the light emitted from the light source;
An illumination optical system that refracts light transmitted through the microlens array;
A TIR prism on which light emitted from the illumination optical system is incident;
With
The illumination optical system includes three lenses in which one concave lens is disposed between two convex lenses,
Among the three lenses, the lens farthest from the microlens array has its optical axis shifted so that the incident angle of the light emitted from the illumination optical system to the total reflection surface of the TIR prism is increased. A light source optical device. A light source;
A microlens array for uniformizing the light emitted from the light source;
An illumination optical system that refracts light transmitted through the microlens array;
An incident prism on which light emitted from the illumination optical system is incident ;
A TIR prisms that light emitted from the incident prism is incident,
With
The illumination optical system includes three lenses in which one concave lens is disposed between two convex lenses,
The light source optical device , wherein the incident prism is arranged in such a direction that an incident angle of light emitted from the illumination optical system to a total reflection surface of the TIR prism is increased.   3. Each microlens of the microlens array is a convex lens in which the focal point of the incident surface and the focal point of the emission surface are in the vicinity of the emission surface and the vicinity of the incident surface, respectively. Light source optical device. Each of the microlenses has a distance along the optical axis from the end of the effective portion of the entrance surface to the point on the optical axis of the exit surface, and is from the point on the optical axis of the entrance surface to the end of the effective portion of the entrance surface. When the maximum distance is h and the refractive index of the glass material is n,
l> h√ (4n ² −1) (Formula 1)
The light source optical device according to claim 3, wherein: 5. The light source optical device according to claim 3 , wherein each microlens of the microlens array has a shape similar to a rectangle of a display element.   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 5.   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. 6. 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 7,
A display element that emits light emitted from the light source optical device to generate projection light;
A projection optical system that projects image light formed by the display element onto a screen;
Projector control means for controlling the display element and the light source optical device;
A projector comprising:

Images