JP2006308778A - Two-lamp synthetic optical system and image projecting device equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid decrease in use efficiency of light and to improve quality of a projected image by homogenizing illuminance distribution of emitting light even when only one lamp in two lamps is turned on. <P>SOLUTION: A deflecting member 16 is disposed on an entrance side of an integrator rod 13 which synthesizes emitting light from a first light source unit 11 and from a second light source unit 12 to emit light with uniform illuminance distribution. The deflecting member 16 transmits and deflects each light in such a manner that the reference axes A, B of the respective emitting light just before entering the integrator rod 13 are almost perpendicular to the entrance face 13a. Even when only one emitting light enters the integrator rod 13, the emitting light from the rod has homogeneous angle distribution with respect to an axis along an optical axis C, and each emitting light produce uniform distribution of light quantity within a pupil of a relay lens group. Even when an image is projected with only one lamp, illuminance irregularity on the plane of a DMD (digital micromirror device) element can be avoided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is used in, for example, a projector, and combines two light beams emitted from two lamps and supplies them to a light modulation element (for example, DMD (Digital Micromirror Device; manufactured by Texas Instruments, USA)). The present invention relates to a system and an image projection apparatus including the system.

  Currently, projectors (especially data projectors) are required to have high brightness, but currently supplied lamps with small system-efficient arcs have limited output. For this reason, in a system (image projection apparatus) using only one such lamp, the output as the system is limited and there is a limit to increasing the brightness. On the other hand, high-power lamps generally have a short life and require frequent maintenance in the market, such as lamp replacement. Therefore, at present, as a lamp optical system for a projector, an illumination optical system that obtains a large output as a system by using two lamps with limited outputs alone has become the mainstream.

  Examples of such illumination optical systems include those disclosed in Patent Documents 1 and 2. In Patent Document 1, light from each light source is condensed on a reflecting surface of a corresponding reflecting means (for example, a mirror) by each condensing optical system (for example, a reflector), and is reflected on a condensing lens system by each reflecting means. I have to. At this time, the condensing positions on the reflecting surfaces of the reflecting means are close to each other and set near the object point of the condensing lens system. As a result, the light reflected from the respective reflecting means to the condenser lens system is superposed on each other to become light with high illuminance, so that an image with high luminance can be obtained.

Moreover, in patent document 2, each light source and each condensing apparatus are made so that the light radiate | emitted from each light source may be superimposed on a color wheel or its vicinity by the condensing apparatus (for example, elliptical mirror) corresponding to each light source. It is arranged. As a result, the light source image formed on or near the color wheel is minimized, and image deterioration due to enlargement of the color wheel or color mixture is avoided.
JP-A-6-242397 Japanese Patent No. 3596357

  By the way, in order to improve the quality of the projection image, it is necessary not only to increase the illuminance of the illumination light but also to make the illuminance distribution of the illumination light uniform. As means for equalizing the illuminance distribution of illumination light, for example, an optical element called an integrator rod is generally known. Therefore, in order to make the illuminance distribution of illumination light uniform with a configuration using a plurality of light sources, it is considered that an integrator rod may be applied to the illumination optical system described in Patent Document 1 or 2, for example.

  However, when the integrator rod is applied to the illumination optical system of Patent Document 1, in order to avoid interference between the light from the light source incident on the reflecting means and the integrator rod, the integrator rod is placed at a certain distance from the reflecting means. Need to be placed. As a result, the amount of light incident on the integrator rod is reduced, leading to a decrease in brightness (a decrease in light utilization efficiency).

  Further, when the integrator rod is simply applied to the illumination optical system of Patent Document 2, when only one of the two lights is lit, the illuminance distribution of the light emitted from the integrator rod can be made uniform. Therefore, there arises a problem that the quality of the projected image is deteriorated. Note that when only one of the two lights is lit, for example, when one of the two lights is not lit due to damage, or when only one lamp is intentionally lit for long life and energy saving. Can think. For example, in the case of a monitoring system that forms a large screen by combining projection images from multiple projectors, it is not possible to respond to an emergency situation if the lamp breaks, so multiple light sources can be turned on as a backup. Only lights one light. If uneven illumination occurs when only one lamp is turned on, the quality of the system will deteriorate. In particular, when one large image is formed by a plurality of projection images, unevenness in illuminance significantly reduces the quality of the projection image. Hereinafter, such a problem will be described in more detail.

  FIG. 12 is an explanatory diagram schematically showing a schematic configuration of a main part of the image projection apparatus when the integrator rod is applied to the illumination optical system of Patent Document 2 as it is. In this apparatus, the light source units 101 and 102 are arranged so that light emitted from the two light source units 101 and 102 is collected on the light incident surface of the integrator rod 103, respectively. The illustration of the color wheel disposed on the light incident side of the integrator rod 103 is omitted. FIG. 13 shows an enlarged view of the light emitted from one light source unit 101 entering the light incident surface of the integrator rod 103 in the illumination optical system of FIG.

  For example, when only one of the light sources 101 is turned on, as shown in FIG. 13, the incident angle of light with respect to the light incident surface of the integrator rod 103 (the angle formed by the optical axis of the light source 101 and the optical axis of the integrator rod 103). The angle distribution of the incident light with respect to the optical axis (or light incident surface) of the integrator rod 103 is greatly biased. As a result, the light amount distribution can be biased in the pupil 104a of the illumination relay system 104 shown in FIG. 12, and the illuminance unevenness occurs on the element surface of the light modulation element 105. Therefore, uneven illuminance occurs in the image projected on the screen via the light modulation element 105, and the quality of the projected image is deteriorated.

  The present invention has been made to solve the above-described problems, and its purpose is to avoid a decrease in light use efficiency and to turn on only one of a plurality of light sources. An object of the present invention is to provide a two-lamp combining optical system capable of improving the quality of a projected image by making the illuminance distribution of emitted light uniform, and an image projecting apparatus including the same.

  The two-lamp combining optical system of the present invention includes a plurality of light source units that emit light, and a combining unit (for example, an integrator rod) that combines the emitted light from each light source unit and outputs the light with a uniform illuminance distribution. A two-lamp combining optical system, in which the optical axis of the light emitted from each light source unit or the axis on the extension line is included in the optical path of each light from each light source unit to the combining unit. As a shaft, each light source unit is arranged such that a part of each reference axis is inclined with respect to the optical axis of the synthesis unit, is provided on the light incident side of the synthesis unit, and is incident on the synthesis unit A deflecting member for transmitting and deflecting each light is provided so that the reference axis of each light just before is substantially perpendicular to the light incident surface of the combining unit.

  In the two-lamp combining optical system of the present invention, the deflecting member is preferably a refractive optical element (which deflects each light by refraction), and is preferably a deflecting prism, for example.

  In the two-lamp combining optical system according to the present invention, the deflection member may be configured such that the thickness in the direction along the optical axis of the combining unit is the thickest at the position farthest from the optical axis, and the optical axis of the combining unit. You may form in the shape which becomes thinnest on the top.

  In the two-lamp combining optical system of the present invention, the light emitting side surface of the deflecting member includes a first light emitting surface that refracts the emitted light from one light source unit and a first light emitting surface that refracts the emitted light from the other light source unit. The first light emitting surface and the second light emitting surface are configured such that each end portion on the optical axis side of the combining portion in each of these surfaces is the optical axis. It may be arranged so as to be inclined with respect to the optical axis of the combining portion so as to be closer to the light incident side surface than each end portion on the opposite side.

  In the two-lamp combining optical system according to the present invention, the deflecting member is a surface perpendicular to a plane including the reference axes, and the deflecting member is divided into two equal parts by a surface including the optical axis of the combining unit. You may comprise by the combination of each prism.

  In the two-lamp combining optical system of the present invention, the surface on the light incident side of the deflecting member includes a first light incident surface that refracts the light emitted from one light source unit and a first light incident surface that refracts the light emitted from the other light source unit. Each of the first light incident surface and the second light incident surface has an end on the optical axis side of the combining portion on each of the surfaces. It may be arranged so as to be inclined with respect to the optical axis of the synthesizing part so as to be closer to the surface on the light emitting side than the end parts on the opposite side.

  In the two-lamp combining optical system according to the present invention, the light exit surface of the combining unit has a quadrangular shape, and the deflecting member is incident on the deflecting member when the optical axis of the combining unit is set as the rotation center. Are arranged at a rotation angle θ with respect to a plane including each reference axis of each light and the optical axis of the combining unit, and the rotation angle θ is determined by the light source image emitted from one light source unit and the other light source. The rotation angle may be such that the light source image by the emitted light of the part is aligned diagonally on the light emitting surface of the combining part.

  In the two-lamp combining optical system according to the present invention, the first light exit surface and the second light exit surface may be configured such that each light refracted by these surfaces is before each light is incident on the deflecting member. You may arrange | position so that it may inject into the said synthetic | combination part on the opposite side mutually with respect to the plane containing a reference axis and the optical axis of the said synthetic | combination part.

In the two-lamp combining optical system according to the present invention, the light incident surface of the combining unit is a quadrangle, the diagonal length of the light incident surface is a, the center of the light incident surface and the light incident surface When the distance between the light collection positions of the light emitted from each light source unit above is b,
(1/8) × a <b <(1/3) × a
It is desirable to satisfy

In the two-lamp combining optical system of the present invention, an angle formed by the optical axis of the combining unit and the reference axis of each outgoing light after being deflected by the deflecting member is α1, and each reference axis is the deflecting member. The point P is located on the opposite side of the optical axis of the combining unit with respect to the point Q, where P is the point that intersects the light emitting side surface of the light source and Q is the point that intersects the light incident surface of the combining unit. When the angle in the case is positive and the angle when the point P is located on the optical axis side of the combining unit with respect to the point Q is negative,
-2 ° <α1 <5 °
It is desirable to satisfy

  In the two-lamp combining optical system of the present invention, each of the light source units includes a light emitting unit (for example, an arc tube) that emits light and a first condensing unit (for example, a rotating paraboloid mirror and a condenser lens) that collects the light. And at least one of the light source units may include a reflection mirror that bends the optical path of the light emitted from the first light collecting unit by reflection.

  In the two-lamp combining optical system according to the present invention, each of the light source units may include the reflection mirror, and the light emitting unit of each of the light source units may be disposed to face each other across the optical axis of the combining unit. .

  In the two-lamp combining optical system of the present invention, each of the light source units further includes a second condensing unit (for example, a condenser lens) that condenses the light reflected by the reflecting mirrors. The light part may be shared by each light source part.

  In the two-lamp combining optical system of the present invention, the combining unit may be a tapered rod having a larger area on the light incident surface than on the light emitting surface.

  The image projection apparatus of the present invention includes the above-described two-lamp combining optical system of the present invention, a light modulation element that modulates light supplied from the two-lamp combining optical system according to image data, and the light modulation element. And a projection optical system that projects the modulated light onto a projection surface (screen).

  According to the present invention, the deflecting member that transmits and deflects (for example, refracts) the emitted light from each light source unit is provided on the light incident side of the combining unit. Thereby, for example, even when at least one of the light source sections has a reflection mirror that bends the optical path of the emitted light, the combining mirror and the deflecting member do not interfere with the light incident on the reflection mirror. It can arrange | position in the position near. As a result, it is possible to avoid a decrease in the utilization efficiency of each outgoing light incident on the combining unit via the deflecting member, and it is possible to avoid a decrease in the brightness of the projected image.

  In addition, each light source unit is arranged such that a part of each reference axis is inclined with respect to the optical axis of the synthesis unit, but the reference axis of each light just before entering the synthesis unit is the light incidence of the synthesis unit Light emitted from each light source unit is transmitted and deflected by the deflecting member so as to be substantially perpendicular to the surface (substantially parallel to the optical axis of the combining unit). As a result, even when only one of the two light source units is incident on the combining unit, the output light has an even (symmetric) angular distribution with respect to an axis parallel to the optical axis of the combining unit. Therefore, the light quantity distribution in the pupil of the optical system (for example, the illumination relay system) after the combining unit is uniform.

  Therefore, even when an image projection apparatus is configured using the two-lamp combining optical system of the present invention and a light modulation element (for example, DMD) and image projection is performed with only one lamp, uneven illuminance on the element surface of the light modulation element. Can be avoided, and uneven illumination can be avoided in the image projected onto the screen via the light modulation element. As a result, the quality of the projected image can be improved even when image projection is performed with only one lamp.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to the drawings.
(1. Configuration of image projection apparatus)
FIG. 2 is a plan view schematically showing a schematic configuration of the image projection apparatus according to the present embodiment, and FIG. 3 is a side view of the image projection apparatus. The image projection apparatus according to this embodiment includes a two-lamp combining optical system 1, a DMD 2, and a projection optical system 3. In FIG. 3, the optical system subsequent to DMD 2 is not shown.

  The two-lamp combining optical system 1 is an optical system for combining the light emitted from the plurality of light source units and supplying the combined light to the DMD 2, and the detailed configuration thereof will be described later.

  The DMD 2 is a light modulation element that arranges micromirrors that are driven ON / OFF according to image data of a display image in a matrix, and modulates light supplied from the two-lamp combining optical system 1 according to the image data. It is. Each mirror of DMD2 corresponds to one pixel. By changing the tilt angle of each mirror according to the image data, the light supplied from the two-lamp combining optical system 1 can be selectively incident on the projection optical system 3 for each pixel. Note that, instead of the DMD 2, for example, a light modulation element may be configured by a reflective or transmissive liquid crystal display device.

  The projection optical system 3 is an optical system for enlarging and projecting the light modulated by the DMD 2 onto the screen 4 that is the projection surface.

(2.2 Configuration of the combined light optical system)
The two-lamp combining optical system 1 includes a first light source unit 11, a second light source unit 12, an integrator rod 13, a color wheel 14, a relay lens group 15, and a deflecting member 16.

  Here, for convenience of explanation below, the “reference axis” is defined as follows. That is, the “reference axis” refers to the first light source unit 11 (or the second light source unit) in the optical path of each light from the first light source unit 11 (or the second light source unit 12) to the integrator rod 13. 12) refers to the optical axis of the emitted light or the axis on the extension line including the optical axis. The “reference axis” is defined as described above. The “optical axis” usually refers to a line connecting the centers of curvature of the optical surfaces of the lens. In Embodiment 3 described later, It is more appropriate to use the concept of “reference axis” defined above than “”, and the terminology used in all the embodiments including the third embodiment is used. Hereinafter, the term “reference axis” is used as necessary, and the reference axis of the first light source unit 11 is A, and the reference axis of the second light source unit 12 is B.

  The first light source unit 11 includes a light emitting unit 21, a rotary parabolic mirror 22, two condenser lenses 23 and 24, and a reflection mirror 25.

  The light emitting unit 21 is composed of an arc tube that emits white light by discharging between two electrodes, and is positioned at the focal point of the rotary parabolic mirror 22. The rotary parabolic mirror 22 reflects the light emitted from the light emitting unit 21 into parallel light. The condenser lenses 23 and 24 converge the collimated light that is reflected by the rotating parabolic mirror 22 and emitted. The parabolic mirror 22 and the condenser lenses 23 and 24 constitute a first condensing unit that condenses the light emitted from the light emitting unit 21 onto the light incident surface 13a of the integrator rod 13. The reflection mirror 25 is an optical element that reflects light emitted from the condenser lens 24 of the first condensing unit in the direction of the light incident surface 13a of the integrator rod 13 and bends the optical path thereof.

  The first light source unit 11 is arranged so that a part of the reference axis A is inclined with respect to the optical axis C of the integrator rod 13. That is, the first light source unit 11 is arranged such that the reference axis A is inclined with respect to the optical axis C in the optical path from the light emitting unit 21 to the deflection member 16. However, since the first light source unit 11 has the reflection mirror 25, the reference axis A is bent by the reflection mirror 25.

  On the other hand, the second light source unit 12 includes a light emitting unit 31, a rotary parabolic mirror 32, and two condenser lenses 33 and 34.

  Like the light emitting unit 21, the light emitting unit 31 is composed of an arc tube that emits white light by discharging between two electrodes, and is positioned at the focal point of the rotary parabolic mirror 32. The rotary parabolic mirror 32 reflects the light emitted from the light emitting unit 31 into parallel light. The condenser lenses 33 and 34 converge the parallel light that is reflected by the rotary parabolic mirror 32 and emitted. The parabolic mirror 32 and the condenser lenses 33 and 34 constitute a first condensing unit that condenses the light emitted from the light emitting unit 31 on the light incident surface 13 a of the integrator rod 13.

  Similarly to the first light source unit 11, the second light source unit 12 is also arranged so that a part of the reference axis B is inclined with respect to the optical axis C of the integrator rod 13. That is, the second light source unit 12 is arranged such that the reference axis B is inclined with respect to the optical axis C in the optical path between the light emitting unit 31 and the deflecting member 16.

  The integrator rod 13 has a quadrangular prism shape in cross section, and the light that has entered the inside from the light incident surface 13a that is one end surface is totally reflected by the side surface to be guided to the light emitting surface 13b that is the other end surface. Let it emit. In particular, in the present embodiment, the integrator rod 13 constitutes a combining unit that combines the light emitted from the first light source unit 11 and the second light source unit 12 and outputs the light with a uniform illuminance distribution. The optical axis C of the integrator rod 13 coincides with the optical axis of the relay lens group 15.

  The color wheel 14 has three types of color filters that selectively transmit red light, green light, and blue light, and is provided on the light emitting side of the integrator rod 13. Each color filter is disposed so as to sequentially traverse the optical path of light emitted from the integrator rod 13 during rotation. Therefore, the rotation of the color wheel 14 causes the white illumination light to be temporally decomposed into red light, green light, and blue light, thereby providing a color image. Thus, it can be said that the color wheel 14 constitutes a time-division color separation optical system.

  The relay lens group 15 includes a plurality of relay lenses and a diaphragm for restricting the light flux, and its optical axis passes through the center of the light incident surface 13a and the center of the light output surface 13b of the integrator rod 13. . The relay lens group 15 optically conjugates the light exit surface 13b of the integrator rod 13 and the element surface (display surface) of the DMD 2.

  The deflecting member 16 is disposed on the light incident side of the integrator rod 13, and the reference axis A of the emitted light from the first light source unit 11 immediately before entering the integrator rod 13 and the emitted light from the second light source unit 12. Each outgoing light is transmitted and deflected so that the reference axis B is substantially perpendicular to the light incident surface 13a of the integrator rod 13 (so as to be substantially parallel to the optical axis C of the integrator rod 13). In the present embodiment, the deflecting prism is a refractive optical element. The details of the deflection member 16 will be described later.

  In the above configuration, the light emitted from the light emitting unit 21 of the first light source unit 11 is reflected by the rotary parabolic mirror 22 to become parallel light, converged by the condenser lenses 23 and 24, and reflected by the reflecting mirror 25. And is incident on the deflecting member 16. On the other hand, the light emitted from the light emitting unit 31 of the second light source unit 12 is reflected by the rotary parabolic mirror 32 to become parallel light, converged by the condenser lenses 33 and 34, and enters the deflecting member 16. .

  In the deflecting member 16, the light emitted from the first light source unit 11 and the second light source unit 12 is refracted, and the reference axes A and B are substantially perpendicular to the light incident surface 13 a of the integrator rod 13. Is incident on the light incident surface 13a. These emitted lights are combined by the integrator rod 13, pass through an arbitrary color filter of the color wheel 14, and enter the DMD 2 through the relay lens group 15. In DMD 2, the tilt angle of each mirror changes depending on the image data, and the light reflected by the mirror that is turned on is projected onto the screen 4 via the projection optical system 3.

  As described above, in the present embodiment, the deflecting member 16 is provided on the light incident side of the integrator rod 13, and each deflected light from the first light source unit 11 and the second light source unit 12 is transmitted by the deflecting member 16. It is deflected (refracted). As a result, the integrator rod 13 and the deflecting member 16 can be arranged close to the reflection mirror 25 without interfering with the light beam incident on the reflection mirror 25 from the light emitting unit 21 via the first light collecting unit. . As a result, it is possible to avoid a decrease in the utilization efficiency of each outgoing light incident on the integrator rod 13, and it is possible to avoid a decrease in the brightness of the projected image.

  Further, in the first light source unit 11, the optical path of the emitted light is bent by the reflection mirror 25, so that the emitted light from the first light source unit 11 and the second light source unit 12 do not interfere with each other, and The first light source unit 11 and the second light source unit 12 can be arranged without causing interference between the light emitted from the second light source unit 12 and the reflection mirror 25. That is, as described above, the first light source unit 11 and the second light source unit 12 can be arranged such that a part of each of the reference axes A and B is inclined with respect to the optical axis C of the integrator rod 13.

(3-1. Configuration of deflection member (1))
Next, details of the above-described deflection member 16 will be described. FIG. 1A is an enlarged plan view showing the main part of the two-lamp combining optical system 1, and FIG. 1B is an enlarged plan view showing the deflection member 16.

  The deflecting member 16 has the thickness in the direction along the optical axis C of the integrator rod 13 in the cross section along the plane including the reference axes A and B, which is the thickest at the position farthest from the optical axis C. The shape is the thinnest on the axis C.

  More specifically, the deflecting member 16 has surfaces 16a and 16b on the light emitting side, and surfaces 16c and 16d on the light incident side. The surface 16a is a first light emitting surface that refracts the emitted light from the first light source unit 11, and the surface 16b is a second light emitting surface that refracts the emitted light from the second light source unit 12. is there. The surface 16c is a first light incident surface that refracts the light emitted from the first light source unit 11, and the surface 16d is a second light incident that refracts the light emitted from the second light source unit 12. Surface. The surfaces 16a and 16b are inclined with respect to the optical axis C so that the end on the optical axis C side is closer to the surfaces 16c and 16d on the light incident side than the end opposite to the optical axis C. Yes. With the arrangement of the surfaces 16a and 16b, the shape of the deflection member 16 can be realized.

  If the deflecting member 16 is configured in such a shape, the reference axes A and B of the respective outgoing lights immediately before entering the integrator rod 13 are substantially perpendicular to the light incident surface 13a of the integrator rod 13. The outgoing light from the first light source unit 11 and the second light source unit 12 can be reliably deflected (refracted) by the deflecting member 16.

  The term “substantially vertical” includes not only the case of being completely vertical but also a case of being slightly deviated from the case of being completely vertical. This point will be described in numerical examples described later.

  As described above, if the reference axes A and B of the respective outgoing lights immediately before entering the integrator rod 13 are substantially perpendicular to the light incident surface 13a of the integrator rod 13, even when image projection is performed with only one lamp. The quality of the projected image can be improved. The reason is as follows.

  If the length of the integrator rod 13 is infinite, even if the incident angle of light with respect to the light incident surface 13a of the integrator rod 13 is increased, sufficient illumination distribution is obtained from the light emitting surface 13b due to total reflection inside the integrator rod 13. It seems that uniform light is emitted. However, since the length of the integrator rod 13 is actually finite, the illuminance distribution cannot be sufficiently uniformed by the integrator rod 13 when the incident angle of light with respect to the light incident surface 13a increases. The light quantity distribution in the pupil of the relay lens group 15 preserves the angular distribution of the light incident on the integrator rod 13 with respect to the optical axis C. When the incident angle with respect to the light incident surface 13a increases, the light quantity distribution in the pupil. Also collapse from uniform.

  From the above, in order to make the light quantity distribution in the pupil of the relay lens group 15 uniform, the angular distribution with respect to the optical axis C of the light incident on the light incident surface 13a of the integrator rod 13 having a finite length is obtained. It can be said that they should be evenly (so as to be symmetric with respect to the axis along the optical axis C). Therefore, with the configuration of the deflecting member 16 described above, if the reference axes A and B of each outgoing light immediately before entering the integrator rod 13 are made substantially perpendicular to the light incident surface 13a of the integrator rod 13, the integrator rod 13 Since the angle distribution with respect to the optical axis C of each outgoing light immediately before entering the lens is substantially uniform, the light quantity distribution in the pupil of the relay lens group 15 can be made uniform for each outgoing light. That is, even when only the emitted light from the first light source unit 11 enters the integrator rod 13 via the deflecting member 16, only the emitted light from the second light source unit 12 passes through the deflecting member 16 to the integrator rod 13. Even when the light is incident on the pupil, the light quantity distribution in the pupil of the relay lens group 15 can be made uniform.

  Even if light is incident on a position deviated from the center of the light incident surface 13a of the integrator rod 13, the light quantity distribution in the pupil of the relay lens group 15 is uniform to some extent as long as the length of the integrator rod 13 is finite. Although it breaks down, the breakage is not as great as when the angular distribution of incident light collapses from uniform, and can be sufficiently compensated by making the angular distribution of incident light uniform.

  Thus, by making the reference axes A and B of the respective outgoing lights just before entering the integrator rod 13 substantially perpendicular to the light incident surface 13a of the integrator rod 13, the first light source unit 11 and the second light source part 11 Even when image projection is performed using only one of the light source units 12, the light amount distribution in the pupil of the relay lens group 15 can be made uniform. As a result, even when image projection is performed with only one lamp, it is possible to avoid uneven illuminance on the element surface of the DMD 2 and to cause uneven illuminance on the image projected on the screen 4 via the DMD 2. Can be avoided, and the quality of the projected image can be improved.

  In the present embodiment, the deflecting member 16 is composed of an optical element (for example, a deflection prism) that transmits and deflects each light emitted from the first light source unit 11 and the second light source unit 12 instead of reflection deflection. This is due to the following reason.

  Since the first light source unit 11 and the second light source unit 12 are located on the light incident side of the integrator rod 13, the deflection member 16 disposed in the vicinity of the light incident surface 13 a of the integrator rod 13 includes: The heat burden from the first light source unit 11 and the second light source unit 12 is very large. At this time, if the deflecting member 16 is formed of a reflective optical element such as a reflecting mirror, the reflecting surface of the reflecting mirror is formed by depositing a dielectric thin film on the substrate. The dielectric thin film may be peeled off by heat from the first light source unit 11 and the second light source unit 12.

  On the other hand, since the transmissive optical element has a characteristic that no thermal energy remains, by using such a transmissive optical element, the deflection member 16 excellent in heat resistance and reliability is realized. can do.

  In particular, the deflecting member 16 is configured by a refractive optical element (for example, a deflecting prism) that deflects each outgoing light by refracting the deflecting member 16, so that the deflecting member 16 can be easily realized by molding or bonding a plurality of prisms to be described later. can do.

(3-2. Configuration of deflection member (2))
The case where the deflection member 16 is configured by a single optical element (deflection prism) has been described above, but may be configured by a combination of a plurality of members. FIG. 4 is a plan view showing another configuration of the deflecting member 16. The deflecting member 16 is a surface perpendicular to the plane including the reference axes A and B, and each of the prisms 16A and 16B formed by equally dividing the deflecting member 16 by the surface including the optical axis C of the integrator rod 13. It consists of pasting together. Note that the bonding of the prisms 16A and 16B may be performed using an adhesive or may be performed without using an adhesive. In the latter case, the prisms 16A and 16B are not bonded to each other but are simply in contact with each other.

  When the deflecting member 16 is constituted by a single optical element, the deflecting member 16 can be formed by, for example, glass molding. On the other hand, when the deflection member 16 is configured by bonding the prisms 16A and 16B, the prisms 16A and 16B are formed by polishing, for example, and these polishing components are bonded to form the deflection member 16. Can do. Therefore, the deflection member 16 can be easily realized only by polishing and bonding.

  In addition, each prism 16A * 16B may be arrange | positioned facing through the space | gap. Therefore, the combination of the prisms 16A and 16B constituting the deflecting member 16 is performed by bonding the prisms 16A and 16B as described above (without using a method of bonding the separation surface of the deflecting member 16 with an adhesive or using an adhesive). A simple contact method) is also included, and an opposing arrangement through the gaps of the prisms 16A and 16B is also included.

(3-3. Configuration of Deflection Member (3))
In the above, the case where the deflecting member 16 is configured by tilting only the light emitting side surfaces 16a and 16b of the deflecting member 16 with respect to the optical axis C has been described. The deflecting member 16 may be configured with an inclination relative to the angle. FIG. 5 is a plan view showing still another configuration of the deflection member 16. In this deflecting member 16, in addition to the configuration of FIG. 1B, the light incident side surfaces 16c and 16d emit light more than the end opposite to the optical axis C at the end on the optical axis C side. It is inclined with respect to the optical axis C so as to approach the side surfaces 16a and 16b.

  In this configuration, since the refractive power of the deflecting member 16 can be made stronger than when only the light emitting surfaces (surfaces 16a and 16b) are inclined with respect to the optical axis C, the first light source unit 11 and the first light source unit 11 The degree of freedom of arrangement and design of the two light source units 12 can be increased.

(3-4. Rotation arrangement of deflection member)
6A and 6B schematically show the positional relationship between the light source image 41 and the light source image 42 on the light emitting surface 13b of the integrator rod 13 determined by the relative positional relationship between the integrator rod 13 and the deflecting member 16. FIG. FIG. The light source image 41 is a light source image formed by the emitted light from the first light source unit 11, and the light source image 42 is a light source image formed by the emitted light from the second light source unit 12. In particular, FIG. 6A shows the deflection member 16 with the optical axis C as the center of rotation with respect to the plane including the reference axes A and B and the optical axis C of each outgoing light before entering the deflection member 16. FIG. 6B shows the positional relationship between the light source images 41 and 42 before the rotation, and FIG. 6B shows the rotation of the deflecting member 16 about the optical axis C with respect to the plane from the state of FIG. The positional relationship between the light source images 41 and 42 in the case where the light source images 41 and 42 are arranged rotated by an angle θ is shown. FIG. 7 shows a state when the deflection member 16 in the state of FIG. 6B is viewed from the light incident side.

  As shown in FIG. 6B, when the deflection member 16 is rotated about the optical axis C, the positions of the light source images 41 and 42 on the light exit surface 13b of the integrator rod 13 are within the light exit surface 13b. Can be changed. At this time, the brightness and the illuminance distribution slightly change depending on the positions of the light source images 41 and 42 on the light emitting surface 13b. However, the light source images 41 and 42 are diagonally arranged on the rectangular light emitting surface 13b. If it is arranged, it is known that light that satisfies both the brightness and the illuminance distribution can be obtained as the light emitted from the integrator rod 13. That is, when the light source images 41 and 42 are arranged in the diagonal direction, both the brightness and the illuminance distribution are close to optimal.

  Therefore, as shown in FIG. 6B, the deflection member 16 is rotated around the optical axis C at the rotation angle θ such that the light source images 41 and 42 are aligned diagonally on the rectangular light emission surface 13b. By rotating and arranging, when using both the first light source unit 11 and the second light source unit 12, both brightness and illuminance distribution are emitted as light emitted from the integrator rod 13. Satisfactory light can be obtained.

  If the rotation angle of the deflection member 16 is appropriately selected, it is possible to optimize only the brightness or only the illuminance distribution. Further, a rotation drive unit (not shown) that rotates the deflection member 16 around the optical axis C may be provided, and various rotation positions of the deflection member 16 may be set by the rotation drive unit.

(3-5. Configuration of Deflection Member (4))
FIG. 8 is a plan view showing still another configuration of the deflection member 16. The deflecting member 16 is configured by arranging the light emitting side surfaces 16a and 16b as follows. That is, the surfaces 16a and 16b are mutually opposite to a plane including the reference axes A and B and the optical axis C of the emitted lights before the emitted lights refracted by these surfaces are incident on the deflecting member 16. They are twisted so as to be incident on the light incident surface 13a of the integrator rod 13 on the opposite side.

  The arrangement of the light emitting surfaces 16a and 16b can also arrange the positions of the light source images 41 and 42 on the light emitting surface 13b of the integrator rod 13 in the diagonal direction. Therefore, even if the deflection member 16 of FIG. 8 is used, the above-described effect obtained by the rotational arrangement of the deflection member 16 as shown in FIG. 6B can be easily obtained.

  6B and FIG. 8, the reference axes A and B of the respective outgoing lights emitted from the deflecting member 16 are not completely parallel, but these deviations are at most about 2 to 3 °. And there is no big difference in angle.

(4. Other)
In the present embodiment, the example in which the first condensing unit of each light source unit is configured by a rotating parabolic mirror and a condenser lens has been described. However, the first condensing unit may be configured by a rotating ellipsoidal mirror. In this case, the light emitting unit may be positioned at one focal position of the spheroid mirror and the light incident surface of the combining unit may be positioned at the other focal position.

  In the present embodiment, an example in which the deflecting member 16 is configured by a deflecting prism has been described. However, the reference axes A and B of each outgoing light immediately before entering the integrator rod 13 are relative to the light incident surface 13a of the integrator rod 13. In other words, it is only necessary to transmit and deflect the emitted light from the first light source unit 11 and the second light source unit 12 so as to be substantially vertical. For example, a lens having such a function may be used. It is.

(5. Numerical examples)
Next, numerical examples of the two-lamp combining optical system 1 are shown as Examples 1 and 2 below.
FIG. 9A is a plan view showing a schematic configuration of the two-lamp combining optical system 1 in Examples 1 and 2. FIGS. 9B, 9C, and 9D are diagrams of the two-lamp combining optical system 1. FIG. It is a top view which expands and shows the deflection | deviation member 16, respectively. In these drawings, the light emitted from the second light source unit 12 and the reference axis B are not shown.

However, each parameter listed in Table 1 is defined as follows.
β: magnification of the relay lens group 15 ω1: angle of light emitted from the rod, that is, integration of light incident on the relay lens group 15
Effective angle (°) on the rod rod 13 side
ω2: Convergence angle (°) of each outgoing light emitted from each light source and entering the deflecting member 16
a: in the diagonal direction on the light incident surface 13a (rectangular shape) of the integrator rod 13
Length (mm)
b: the center of the light incident surface 13a of the integrator rod 13 and each light source part
Distance from each light collection position (mm)
L1: Light incident surface 13a of integrator rod 13 and light emitting side surface of deflection member 16
On-axis distance between (mm)
L2: thickness of the deflecting member 16 on the optical axis C (mm)
n: Refractive index of the deflecting member 16 γ1: The light emitting side surface of the deflecting member 16 and the optical axis C are formed on the integrator rod 13 side.
Angle (°)
γ2: The light incident side surface of the deflecting member 16 and the optical axis C are opposite to the integrator rod 13
Side angle (°)
α1: Angle formed between the optical axis C and the reference axes A and B of each outgoing light after being deflected by the deflecting member 16
Degree (°)
(However, the convergence side is positive and the divergence side is negative. The convergence side is the reference axis A (B).
Is the point where the crossing with the light exit side surface of the deflecting member 16 is P, and the integrator rod 1
When the point (condensing position) that intersects the light incident surface 13a of 3 is defined as Q,
The case where the point P is located on the opposite side to the optical axis C is indicated. On the other hand, the divergent side is
In this case, the point P is located on the optical axis C side. )
α2: Angle (°) formed by the optical axis C and the reference axes A and B of the light before passing through the deflecting member 16

  Here, as for a and b, it is desirable to satisfy the relationship of (1/8) × a <b <(1/3) × a. When b is equal to or lower than the lower limit value, the reference axes A and B of the respective outgoing lights can be made substantially perpendicular to the light incident surface 13a of the integrator rod 13 without causing the outgoing lights from the respective light source units to interfere with each other. It becomes difficult. On the other hand, when b is equal to or larger than the upper limit value, the condensed spot of each emitted light from each light source unit may protrude from the light emitting surface 13a. In this case, each emitted light cannot be effectively used.

  In this regard, in Examples 1 and 2, the above conditional expression is satisfied. Therefore, the integrator rod can be used even when only one lamp is lit while the reference beams A and B are made substantially perpendicular to the light incident surface 13a while effectively using the light emitted from each light source unit without causing interference. The illuminance distribution of the emitted light from 13 can be made uniform.

  Α1 is desirably an angle satisfying −2 ° <α1 <5 °. If α1 is within this range, the reference axes A and B of each outgoing light incident on the light incident surface 13a of the integrator rod 13 are substantially perpendicular to the light incident surface 13a, and along the optical axis C of each outgoing light. The angle distribution with respect to the axis can be made substantially uniform. Therefore, even when only one lamp is lit, the illuminance distribution of the emitted light from the integrator rod 13 can be made uniform.

  When α1 is less than or equal to the lower limit value, the light emitted from the integrator rod 13 becomes divergent light having a large light beam angle, so that light that is not taken into the relay lens group 15 is generated, which is disadvantageous in terms of light transmission. . Therefore, α1 is desirably larger than −2 °. In this regard, in Examples 1 and 2, the above conditional expression is satisfied.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to the drawings. In the present embodiment, the configuration other than the configuration of the first light source unit 11 and the second light source unit 12 of the two-lamp combining optical system 1 is implemented, such as a deflecting member 16 provided on the light incident side of the integrator rod 13. It is the structure similar to the form 1. For convenience of explanation, the same components as those in the first embodiment are denoted by the same member numbers, and the description thereof is omitted.

  FIG. 10 is a plan view showing a schematic configuration of a main part of the two-lamp combining optical system 1 of the present embodiment. In the present embodiment, both the first light source unit 11 and the second light source unit 12 have reflection mirrors 25 and 35, respectively. The reflection mirror 35 is an optical element that bends the light path of the light emitted from the condenser lens 34 of the first light collecting unit by reflection. And the 1st light source part 11 and the 2nd light source part 12 are arrange | positioned so that the light emission parts 21 * 31 may oppose on both sides of the optical axis C of the integrator rod 13. FIG.

  As described above, since both the first light source unit 11 and the second light source unit 12 have the reflection mirrors 25 and 35, the light sources from the first light source unit 11 and the second light source unit 12 are output. The incident light can be incident on the integrator rod 13 without interfering with each other. Therefore, even with this configuration, it is possible to reliably obtain a high-luminance projection image by using the emitted light from the first light source unit 11 and the second light source unit 12.

  Further, by arranging the light emitting units 21 and 31 to face each other with the optical axis C interposed therebetween, for example, they can be arranged at the same height position. In this arrangement, even if the projection position is changed, if the entire apparatus is rotated around the axis connecting the light emitting units 21 and 31, the light emitting units 21 and 31 are inclined with respect to the plane perpendicular to the vertical direction. There is nothing. When the light emitting units 21 and 31 are inclined with respect to the plane perpendicular to the vertical direction, the operations of the light emitting units 21 and 31 become unstable. However, according to the above configuration, the operations of the light emitting units 21 and 31 are stabilized. It is possible to change only the installation state of the apparatus while maintaining the above.

[Embodiment 3]
The following will describe still another embodiment of the present invention with reference to the drawings. The present embodiment is the same as the second embodiment in that the deflecting member 16 is provided on the light incident side of the integrator rod 13, but the combining unit, the first light source unit 11, and the second light source unit 12 The configuration is slightly different from that of the second embodiment. For convenience of explanation, the same members as those in the first or second embodiment are denoted by the same member numbers, and the explanation thereof is omitted.

  FIG. 11 is a plan view showing a schematic configuration of a main part of the two-lamp combining optical system 1 of the present embodiment. In the present embodiment, as in the second embodiment, the first light source unit 11 and the second light source unit 12 have reflection mirrors 25 and 35, respectively, and the light emitting units 21 and 31 are light beams from the integrator rod 13. It arrange | positions so that the axis | shaft C may be pinched | interposed.

  In the present embodiment, a taper rod 51 is provided as a synthesizing part instead of the integrator rod 13. The tapered rod 51 is a tapered integrator rod having a light incident surface 51a having a larger area than the light emitting surface 51b. By forming the combining unit with such a tapered rod 51, the first light source unit 11 and the second light source unit 11 are compared with the case where the integrator rod 13 having the same area of the light emitting surface 13b and the light incident surface 13a is used. The efficiency of capturing each outgoing light from the light source unit 12 can be increased, and each outgoing light can be used effectively.

  Moreover, in this embodiment, the 1st light source part 11 contains the 1st condensing part and the 2nd condensing part. However, in the 1st light source part 11, the 1st condensing part is comprised by the rotating paraboloid mirror 22 and the condenser lens 23, and the 2nd condensing part is comprised by the condenser lens 52. FIG. On the other hand, the 2nd light source part 12 also contains the 1st condensing part and the 2nd condensing part. However, in the second light source unit 12, the first condensing unit is configured by the rotary parabolic mirror 32 and the condenser lens 33, and the second condensing unit is configured by the condenser lens 52. That is, the condenser lens 52 is shared by the first light source unit 11 and the second light source unit 12. The condenser lens 52 is disposed between the reflecting mirrors 25 and 35 and the taper rod 51.

  By disposing the condenser lens 52 between the reflecting mirrors 25 and 35 and the taper rod 51, the first light source unit 11 and the second light source unit 12 can be connected without lowering the utilization efficiency of each emitted light. It is possible to dispose the taper rod 51 away. As a result, as shown in FIG. 11, the color wheel 14 can be disposed between the tapered rod 51 and the condenser lens 52 so as not to interfere with the first light source unit 11 and the second light source unit 12. Become. That is, a space for arranging the color wheel 14 can be secured between the taper rod 51 and the condenser lens 52.

  Here, since the light exit surface of the combining portion (here, the taper rod 51) and the element surface of the light modulation element (here, DMD2) are optically substantially conjugate by the relay lens group 15, the color wheel 14 is When arranged on the light emitting side of the combining unit, when the boundary portion of each color filter of the color wheel 14 crosses the light emitting surface of the combining unit, the mixed color is reflected as it is on the element surface, and partial color unevenness on the element surface. Occurs. However, when the color wheel 14 is arranged on the light incident side of the combining unit, even if light passes near the boundary of each color filter of the color wheel 14, mixed color light is mixed by the combining unit and supplied to the light modulation element. Therefore, partial color unevenness on the element surface of the light modulation element can be suppressed.

  In this embodiment, since the condenser lens 52 is shared by the first light source unit 11 and the second light source unit 12, the total number of condenser lenses is smaller than in the first and second embodiments ( (4 sheets to 3 sheets) and the number of parts can be reduced.

  In the present embodiment, the optical axis from the light emitting unit 21 of the first light source unit 11 to the condenser lens 52 is bent by the reflecting mirror 25, and this optical axis is the curvature of the light incident surface of the condenser lens 52. Not through the center. Therefore, the optical axis of the first light source unit 11 is not suitable to be called an optical axis in the optical path after the reflection mirror 25. The same applies to the optical axis of the second light source unit 12.

  Therefore, as described in the first embodiment, the reference axes A and B are defined. In the present embodiment, the reference axis A includes the optical axis from the light emitting unit 21 to the reflecting mirror 25 in the optical path from the first light source unit 11 (light emitting unit 21) to the combining unit (tapered rod 51). Refers to the axis on the extension line. The reference axis B includes an optical axis from the light emitting unit 31 to the reflecting mirror 35 in the optical path from the second light source unit 12 (light emitting unit 31) to the (tapered rod 51), and is on an extension line thereof. Point to.

  By defining the reference axes A and B in this way, even in the configuration of the present embodiment using the condenser lens 52, the reference axes A and B of the respective outgoing lights immediately before entering the combining unit are the light incident surfaces of the combining unit. Therefore, the function of the deflecting member 16 for transmitting and deflecting each emitted light can be accurately expressed so as to be substantially perpendicular to the above.

  Of course, it is possible to combine the configurations of the embodiments described above. For example, various configurations of the deflecting member 16 of the first embodiment can of course be applied to the second and third embodiments, and the tapered rod 51 of the third embodiment is applied to the first and second embodiments. Of course it is possible.

(A) is a top view which expands and shows the principal part of the 2 lamp | ramp synthetic | combination optical system used for the image projector which concerns on one Embodiment of this invention, (b) is the said 2 lamp | ramp synthetic | combination optical system. It is a top view which expands and shows a deflection | deviation member. It is a top view which shows typically the schematic structure of the said image projector. It is a side view of the said image projector. It is a top view which shows the other structure of the said deflection | deviation member. It is a top view which shows other structure of the said deflection | deviation member. (A) is explanatory drawing which shows typically the positional relationship of each light source image on the light-projection surface of the integrator rod before rotation of a deflection | deviation member, (b) of the integrator rod after rotation of a deflection | deviation member is shown. It is explanatory drawing which shows typically the positional relationship of each light source image on a light-projection surface. It is explanatory drawing which shows a state when the said deflection | deviation member after rotation is seen from the light-incidence side. It is a top view which shows other structure of the said deflection | deviation member. (A) is a top view which shows the general | schematic structure of the 2 lamp | ramp synthetic | combination optical system in each Example, (b) (c) (d) expands the deflection | deviation member of the said 2 lamp | ramp synthetic optical system, respectively. FIG. It is a top view which shows the schematic structure of the principal part of the 2 lamp | ramp synthetic optical system which concerns on other embodiment of this invention. It is a top view which shows the structure of the outline of the principal part of the 2 lamp | ramp synthetic optical system which concerns on other embodiment of this invention. It is explanatory drawing which shows typically the structure of the outline of the principal part of an image projection apparatus at the time of applying an integrator rod as it is to the conventional illumination optical system. It is explanatory drawing which expands and shows a mode that the emitted light from one light source part injects into the light-incidence surface of an integrator rod in the illumination optical system of the said image projector.

Explanation of symbols

1 Two-lamp composite optical system 2 DMD (light modulation element)
3 Projection optical system 4 Screen (projection surface)
DESCRIPTION OF SYMBOLS 11 1st light source part 12 2nd light source part 13 Integrator rod (synthesis | combination part)
13a Light incident surface 13b Light emitting surface 16 Deflection member 16a surface (light emitting surface)
16b surface (light exit surface)
16c surface (light incident surface)
16d surface (light incident surface)
16A prism 16B prism 21 light emitting unit 22 rotating parabolic mirror (first condensing unit)
23 Condenser lens (first condensing part)
24 condenser lens (first condensing part)
25 Reflecting mirror 31 Light emitting unit 32 Rotary parabolic mirror (first condensing unit)
33 Condenser lens (first condensing part)
34 Condenser lens (first condensing part)
35 Reflecting mirror 41 Light source image 42 Light source image 51 Tapered rod (synthesis unit)
52 Condenser lens (second condenser)
A Optical axis B Optical axis C Optical axis

Claims (16)

A plurality of light source units that emit light;
A two-lamp combining optical system including a combining unit that combines the light emitted from each light source unit and outputs the light with a uniform illuminance distribution;
In the optical path of each light from each light source unit to the synthesis unit, the optical axis of the emitted light of each light source unit, or the axis on the extension line including the optical axis as a reference axis,
Each light source unit is arranged such that a part of each reference axis is inclined with respect to the optical axis of the combining unit,
A deflection that is provided on the light incident side of the combining unit and transmits and deflects each light so that the reference axis of each light immediately before entering the combining unit is substantially perpendicular to the light incident surface of the combining unit. A two-lamp composite optical system comprising a member.   The two-lamp combining optical system according to claim 1, wherein the deflecting member is a refractive optical element.   The two-lamp combining optical system according to claim 1 or 2, wherein the deflecting member is a deflecting prism.   The two-lamp combining optical system according to claim 3, wherein the deflecting member is formed in a shape that is thinnest on the optical axis of the combining unit. The surface on the light emission side of the deflection member is composed of a first light emission surface that refracts the emitted light of one light source unit and a second light emission surface that refracts the emitted light of the other light source unit. And
In the first light emitting surface and the second light emitting surface, each end on the optical axis side of the combining portion in each of these surfaces is more incident than each end on the side opposite to the optical axis. 5. The two-lamp combining optical system according to claim 4, wherein the two-lamp combining optical system is disposed to be inclined with respect to the optical axis of the combining unit so as to approach the side surface.   The deflecting member is a surface perpendicular to a plane including the reference axes, and is constituted by a combination of prisms obtained by dividing the deflecting member into two equal parts by a surface including the optical axis of the combining unit. The two-lamp combining optical system according to any one of claims 3 to 5, wherein The surface on the light incident side of the deflecting member is composed of a first light incident surface that refracts the emitted light of one light source unit and a second light incident surface that refracts the emitted light of the other light source unit. And
The first light incident surface and the second light incident surface are such that each end on the optical axis side of the combining portion on each of these surfaces emits light more than each end on the side opposite to the optical axis. 7. The two-lamp combining optical system according to claim 5, wherein the two-lamp combining optical system is disposed to be inclined with respect to the optical axis of the combining unit so as to approach the side surface. The light emission surface of the synthesis part is a quadrangle shape,
The deflection member has a rotation angle θ with respect to a plane including the reference axis of each light before entering the deflection member and the optical axis of the combining unit when the optical axis of the combining unit is set as the rotation center. Arranged in the
The rotation angle θ is a rotation angle such that the light source image by the light emitted from one light source unit and the light source image by the light emitted from the other light source unit are aligned diagonally on the light emission surface of the synthesis unit. The two-lamp combining optical system according to any one of claims 3 to 7, wherein   The first light exit surface and the second light exit surface are configured such that each light refracted by these surfaces is a reference axis of each light before entering the deflecting member, and an optical axis of the combining unit. 8. The two-lamp combining optical system according to claim 5, wherein the two-lamp combining optical system is disposed so as to be incident on the combining unit on opposite sides to a plane including. The light incident surface of the synthesis unit is a quadrangular shape,
When the diagonal length of the light incident surface is a, and the distance between the center of the light incident surface and the condensing position of the emitted light from each light source unit on the light incident surface is b,
(1/8) × a <b <(1/3) × a
The two-lamp combining optical system according to any one of claims 1 to 9, wherein: The angle formed between the optical axis of the combining unit and the reference axis of each outgoing light after being deflected by the deflecting member is α1, and the point at which each reference axis intersects the light emitting side surface of the deflecting member. P, where Q is the point that intersects the light incident surface of the combining unit, the angle when the point P is located on the opposite side of the optical axis of the combining unit with respect to the point Q is positive and point Q On the other hand, when the angle when the point P is located on the optical axis side of the combining unit is negative,
-2 ° <α1 <5 °
The two-lamp combining optical system according to any one of claims 1 to 10, wherein: Each light source unit includes a light emitting unit that emits light and a first light collecting unit that collects the light,
The at least one of each said light source part contains the reflective mirror which bends | reflects the optical path of the light radiate | emitted from the said 1st condensing part by reflection, The Claim 1 characterized by the above-mentioned. Two-lamp synthetic optical system. Each of the light sources includes the reflection mirror,
The two-lamp combining optical system according to claim 12, wherein the light emitting units of the respective light source units are arranged to face each other with the optical axis of the combining unit interposed therebetween. Each light source unit further includes a second light collecting unit that collects the light reflected by each reflection mirror,
The two-lamp combining optical system according to claim 13, wherein the second light collecting unit is shared by the light source units.   The two-lamp combining optical system according to any one of claims 1 to 14, wherein the combining unit is a tapered rod having a larger area on the light incident surface than on the light emitting surface. A two-lamp combining optical system according to any one of claims 1 to 15,
A light modulation element that modulates light supplied from the two-lamp combining optical system according to image data;
An image projection apparatus comprising: a projection optical system that projects light modulated by the light modulation element onto a projection surface.

Images