CN115327842A - Projection display device - Google Patents

Abstract

A high-quality, compact, low-cost projection display device includes: a dichroic mirror that splits light from the light source into first illumination light of first color light and second illumination light of second color light; a first illumination optical system that guides the first illumination light to the first reflective light modulation device; a second illumination optical system that guides the second illumination light to the second reflective light modulation device; a combining prism that transmits the first image light output from the first reflective light modulation device through the dielectric multilayer film, reflects the second image light output from the second reflective light modulation device through the dielectric multilayer film to change an optical path, and emits combined light obtained by combining the first image light and the second image light; a first rear group lens; a second rear group lens; and a front group lens which is arranged closer to the enlargement side than the synthesis prism and acts on the synthesis light, wherein the incident angles of the first image light and the second image light to the medium multilayer film are substantially equal in magnitude and are 10 degrees or more and 27 degrees or less.

Description

Projection display device

Technical Field

The present invention relates to a two-plate type projection display device including two reflective light modulation devices.

Background

Conventionally, there is known a projection display apparatus which includes a light modulation Device such as a Digital Micromirror Device (DMD) or a liquid crystal Device, and a projection optical system, and which displays a color image by enlarging and projecting the color image on a screen or the like.

For example, a single-panel type projection display device is known which irradiates a single-panel light modulation device with illumination light of different colors while switching the illumination light at high speed, and performs time-division projection of images of different colors. The light modulation device is advantageous in terms of cost reduction and device miniaturization because it can perform color display even with a single plate, but it is difficult to achieve high luminance because it displays images of different display colors while switching them in time division. Further, when a switching color filter is used in combination with a white light source to generate illumination light whose color is switched in a time-division manner, only a part of white light is used, and there is a problem that power consumption is increased due to low light utilization efficiency.

As a method different from the single-plate type, a three-plate type projection display apparatus is known which includes three light modulation devices, irradiates each light modulation device with illumination light of different colors (for example, red (R), green (G), and blue (b)), and synthesizes and projects display images of different colors output from each light modulation device using a cross dichroic prism or the like. Since the brightness can be increased as compared with the single-plate type, the optical system is suitable for use in large-sized screens such as movies, but since the optical system has a complicated structure and the number of components is large, it is difficult to reduce the cost and the size of the device, and the use is limited.

Therefore, in order to realize a device having high versatility and excellent balance among high brightness, miniaturization, and cost reduction, a two-plate type projection display device including two light modulation devices has been attempted.

For example, patent document 1 describes a projection display device including: a light source unit; a dichroic mirror that separates light emitted from the light source unit into first color light and second color light; a first light modulation device for modulating the first color light; the second light modulation device modulates the second color light; and a color synthesis prism for performing color synthesis on the first color light modulated by the first light modulation device and the second color light modulated by the second light modulation device. The device further includes a projection unit for projecting the synthesized light emitted from the color synthesis prism.

Patent document 2 discloses a projection display device including: a polarized cross dichroic prism for separation for separating the light from the light source unit; a first light modulation device and a second light modulation device; the polarizing cross dichroic prism for synthesis synthesizes output light of the first light modulation device and output light of the second light modulation device. The light source module of the apparatus is configured to irradiate the first light modulation device and the second light modulation device with blue light, respectively, during a first display period, and to irradiate the first light modulation device with green light and the second light modulation device with red light, respectively, during a second display period.

Patent document 1: japanese patent laid-open publication No. 2018-146951

Patent document 2: international publication No. 2018/073893

In the method described in patent document 1, when the incident angle to the dichroic mirror is θ 1 and the incident angle to the color synthesis prism is θ 2, the optical devices are laid out by setting angles at θ 1=55 degrees and θ 2=35 degrees. As shown in fig. 1 of the document, a prism assembly in which a Total Internal Reflection (TIR) prism and a color synthesis prism are integrated is disposed between an optical modulation device and a projection lens, and an incident angle θ 2 to the color synthesis prism is set to 35 degrees, so that a back focal length of the projection lens becomes larger than that of a three-plate type, which means that the size of the apparatus is not necessarily reduced.

In addition, in patent document 1, the miniaturization of the apparatus is achieved by arranging the optical modulation device so as to be symmetrical with respect to the color synthesis plane of the color synthesis prism, but as a result of setting θ 2=35 degrees as described above, it is difficult to apply the reflective optical modulation device of the type which is most popular and advantageous in terms of cost. As shown in fig. 15, the most popular and cost-advantageous reflective light modulation devices are of the following type: a plurality of micromirrors are two-dimensionally arranged on a screen, each of which is driven in such a manner that a reflecting surface is inclined to + -12 degrees at the time of on/off (on/off). In this device, as shown in an enlarged scale at the upper left corner of the drawing, on light to be displayed and off light not to be displayed are reflected in different directions, but as a result of symmetrically arranging the optical modulation devices by θ 2=35 degrees in the apparatus of patent document 1, a geometric arrangement that can reflect on light in the direction of the projection lens and off light in the direction outside the projection lens cannot be established. Therefore, when the method described in patent document 1 is implemented, it is not possible to use a reflective light modulation device of a type advantageous in terms of cost, but it is necessary to use a reflective light modulation device in which the off-angle direction of the micromirror is the horizontal direction (H direction) or the vertical direction (V direction) of the screen.

In the method described in patent document 2, a polarizing cross dichroic prism is used as a means for color-combining the output light of the two light modulation devices, but the polarization characteristics of the cross dichroic prism greatly change depending on the incident angle. Therefore, for example, in an actual optical system in which the F value is about 2.5 and the in-plane incident angle deviation is ± 12 degrees, there is a problem that color shading (color unevenness) occurs significantly in the display screen and the display image quality is degraded.

Therefore, a two-panel type projection display device having high versatility, which is well balanced between high image quality with uniform color depth (less color unevenness) and miniaturization and is low in cost, has been demanded.

Disclosure of Invention

One aspect of the present invention is a projection display device including: a light source; a light tunnel that propagates light from the light source along an optical axis disposed in a first plane; a dichroic mirror that splits light from the light source incident via the light channel into first illumination light of first color light and second illumination light of second color light; a first illumination optical system that guides the first illumination light reflected by the dichroic mirror to a first reflective light modulation device; a second illumination optical system that guides the second illumination light transmitted from the dichroic mirror to a second reflective light modulation device; a combining prism that transmits the first image light output from the first reflective light modulation device through the dielectric multilayer film, reflects the second image light output from the second reflective light modulation device through the dielectric multilayer film to change an optical path, and emits combined light obtained by combining the first image light and the second image light; a first rear group lens which is arranged between the synthesis prism and the first reflection type light modulation device and acts on the first image light; a second rear group lens, disposed between the combining prism and the second reflective light modulator, and acting on the second image light; and a front group lens which is arranged closer to the enlargement side than the synthesis prism and acts on the synthesis light, wherein the incident angles of the first image light and the second image light to the medium multilayer film are substantially equal in magnitude and are 10 degrees or more and 27 degrees or less.

The present invention can provide a two-panel projection display device having high versatility, which is well balanced between high image quality with uniform color depth and miniaturization and is low in cost.

Drawings

Fig. 1 is a typical view showing an optical configuration of a projection display device according to embodiment 1.

Fig. 2 is a diagram showing a part of the illumination optical system in embodiment 1.

Fig. 3 is a diagram showing a projection optical system in embodiment 1.

Fig. 4 (a) is a diagram showing the structure of the synthesis prism 400; fig. 4 (b) is a diagram showing characteristics of the dielectric multilayer film 405.

Fig. 5 is a graph showing characteristics of the dichroic mirror 180.

Fig. 6 is a diagram showing the arrangement of the optical devices when the reflective light modulation device 200b is viewed from the back surface side in embodiment 1.

Fig. 7 (a) is a diagram typically showing an illumination optical system from the light tunnel 140 to the reflective light modulation device 200 a; fig. 7 (b) is a diagram typically showing an illumination optical system from the light tunnel 140 to the reflective light modulation device 200b.

Fig. 8 (a) is a diagram showing the structure of a light source device 110 used in embodiment 1; fig. 8 (b) is a diagram showing the structure of the light source device 110 used in embodiment 2.

Fig. 9 (a) is a graph showing the transmission characteristics of the cyan filter CF; fig. 9 (b) is a graph showing the transmission characteristics of the red filter RF.

Fig. 10 is a typical view showing an optical configuration of a projection display device according to embodiment 2.

Fig. 11 is a diagram showing a part of the illumination optical system in embodiment 2.

Fig. 12 is a diagram showing a projection optical system in embodiment 2.

Fig. 13 (a) is a diagram showing the structure of the synthesis prism 410; fig. 13 (b) is a diagram showing characteristics of the dielectric multilayer film 415.

Fig. 14 is a diagram showing the arrangement of the optical devices when the reflective light modulation device 200b is viewed from the back side in embodiment 2.

Fig. 15 is a diagram for explaining the structure of the reflection type light modulation device.

Fig. 16 is a plan view of the rotating body.

Fig. 17 is a graph showing the emission characteristics of the phosphor (fluorescent material).

Fig. 18 (a) is a timing chart showing color light of the illumination light IL output from the light source device 110 according to embodiment 1; fig. 18 (b) is a timing chart showing color light of the first illumination light according to embodiment 1; fig. 18 (c) is a timing chart showing image light output from the reflective light modulation device 200a according to embodiment 1; fig. 18 (d) is a timing chart showing color light of the second illumination light according to embodiment 1; fig. 18 (e) is a timing chart showing the image light output from the reflective light modulation device 200b according to embodiment 1.

Fig. 19 (a) is a timing chart showing color light of the illumination light IL output from the light source device 110 according to embodiment 2; fig. 19 (b) is a timing chart showing color light of the first illumination light according to embodiment 2; fig. 19 (c) is a timing chart showing image light output from the reflective light modulation device 200a according to embodiment 2; fig. 19 (d) is a timing chart showing color light of the second illumination light according to embodiment 2; fig. 19 (e) is a timing chart showing image light output from the reflective light modulation device 200b according to embodiment 2.

Fig. 20 (a) is a timing chart showing the color light of the illumination light IL output from the light source device 110 according to embodiment 2; fig. 20 (b) is a timing chart showing color light of the first illumination light according to embodiment 2; fig. 20 (c) is a timing chart showing image light output from the reflective light modulation device 200a according to embodiment 2; fig. 20 (d) is a timing chart showing color light of the second illumination light according to embodiment 2; fig. 20 (e) is a timing chart showing the image light output from the reflective light modulation device 200b according to embodiment 2.

Description of the reference numerals

1\8230Aprojector

110- (8230); 8230and light source device

105- (8230); 8230and dichroic mirror

107 \8230 \ 8230and 1/4 wavelength plate

109 of 823080, 8230and condensing lens

111R (8230) (\ 8230), solid light source emitting red light

112B 823060, 8230and solid light source emitting blue light

113G 823060, 8230and solid light source emitting green light

121\8230amotor

122 (8230); 8230and rotary body

123- (8230); 8230and fluorescent body

123Y 823060 \ 8230and yellow fluorescent body

124, 823060, 8230a reflecting part

140, 823060, 8230and light channel

150 (8230); 8230and light channel side condenser lens

151\8230, 8230and intermediate image side condenser lens

155 (8230); 8230and enlarged intermediate image

160- (8230); 8230am intermediate image-side condenser lens

161 (8230) (\ 8230), intermediate image side condenser lens

162 (8230) (\ 8230), relay lens

163 \8230 \ 8230and light gathering lens at modulation device side

170a, 170b 823060 \8230;, TIR prism

180 (8230); 8230and dichroic mirror

181\8230alamp 8230a light path change reflector

182a, 182b, 823060 \ 8230and reflecting mirror

200a, 200b, 823060, 8230reflective light modulation device

210 (8230) (\ 8230), exciting light source assembly

400 (8230); 8230and synthetic prism

401. 402, 403, 823060, 8230while

405, 8230while dielectric multilayer film

410 (8230); 8230and synthetic prism

411. 412 (8230); 8230and prism

415, 8230, 8230dielectric multilayer film

601a \823060 \ 8230and the first rear group lens

601b (8230) \ 8230and the second rear group of lenses

602, 823060, 8230and front lens group

610 8230A, 8230and projection optical system

611a (8230); 8230and the first relay lens

611b 823060; \ 8230; second relay lens

60 (8230); 8230and projection optical system

612 \ 8230; \ 8230and third relay lens

613 \ 8230; \ 8230; intermediate image

614 (8230); 8230and projection lens

700 (8230); 8230and projection plane

AG1, AG2, AG3 \8230: \8230airgap

Ex 823060, 8230and exciting light

IL (8230); 8230and illuminating light

LX 823060, 8230and optical axis of front lens group

Detailed Description

The projection display device according to the embodiment will be described below with reference to the drawings.

[ embodiment 1]

Fig. 1 is a typical view showing an optical configuration of a projection display device according to embodiment 1. The projection display apparatus 1 includes a reflective light modulation device 200a (first reflective light modulation device) and a reflective light modulation device 200b (second reflective light modulation device). In the present embodiment, a DMD in which micromirror devices are arranged in an array is used as the reflective light modulation devices 200a and 200b. As described with reference to fig. 15, the DMD is a device in which the reflection surface of each pixel micromirror is inclined by 45 ° with respect to the frame of the screen when the screen is viewed from above, and the reflection surface is driven in accordance with an image signal to change the reflection direction of the illumination light. The micromirrors corresponding to the respective pixels are driven according to the brightness levels of image signals so that the reflection directions are changed by pulse width modulation.

The projection display device 1 includes a light source device 110. The light source device 110 is a light source for illuminating the reflective light modulation device 200a and the reflective light modulation device 200b. Fig. 8 (a) shows a structure of the light source device 110 used in the present embodiment. The light source apparatus 110 includes an excitation light source unit 210, and the excitation light source unit 210 is a unit in which a plurality of light emitting devices (for example, semiconductor lasers that emit blue light) are two-dimensionally arranged and collimating lenses are provided corresponding to the light emitting devices. The light source device 110 includes a rotating body 122 rotatable by a motor 121, and a fluorescent material (fluorescent material) 123 is provided on a main surface of the rotating body 122. Further, a dichroic mirror 105, a 1/4 wavelength plate 107, and a condenser lens are disposed between the excitation light source unit 210 and the fluorescent substance 123.

In the light source device of the present embodiment, the rotating body 122 is rotatable by the motor 121, and the fluorescent material 123 is provided on the principal surface of the rotating body 122. Fig. 16 shows a plan view of the rotating body 122, and on a main surface of the rotating body 122, a yellow phosphor 123Y is coated on a part of a ring-shaped region centered on the rotation axis RA, and a reflecting portion 124 for reflecting excitation light Ex is provided on the remaining part of the ring-shaped region without coating a phosphor. The reflection unit 124 is preferably mirror-finished in advance to efficiently reflect the blue laser beam. A reflecting surface for reflecting the fluorescent light emitted in the direction of the rotary body 122 toward the lens side is provided on the base of the region where the yellow fluorescent body 123Y is provided, so as to improve the emission efficiency of the fluorescent light.

Fig. 17 shows an example of a spectrum obtained from the yellow phosphor 123Y when the excitation light Ex is irradiated to the yellow phosphor 123Y. A graph 32 shown by a one-dot chain line in the figure is an emission spectrum of the yellow phosphor 123Y. For reference, the emission spectrum of a general green phosphor is shown by a dotted-line graph 31, and the emission spectrum of a general red phosphor is shown by a solid-line graph 33. The peak observed at a wavelength of about 450nm is not light emitted from the phosphor, but light obtained by reflecting a part of the excitation light Ex without being absorbed by the phosphor. The graph 32 shown in fig. 17 is an example, and the emission characteristics of the phosphor that can be used in the present embodiment do not necessarily have to be exactly the same.

By rotating the rotating body 122, the excitation light Ex is irradiated to either the yellow fluorescent material 123Y or the reflecting portion 124. In order to prevent the phosphor from overheating, it is preferable to use a metal having high thermal conductivity as the base material of the rotating body 122, and in order to improve the air cooling efficiency, a concave-convex portion or a void may be provided in the base material.

Next, the operation of each part of the light source device 110 will be described with reference to fig. 8 (a).

The collimated S-polarized blue light (excitation light Ex) emitted from the excitation light source assembly 210 enters the dichroic mirror 105. The S-polarized blue light (excitation light Ex) is reflected by the dichroic mirror 105 in the direction of the rotating body 122. The excitation light passed through the 1/4 wavelength plate 107 is condensed by the condenser lens onto the rotating body 122.

In a rotation period in which the yellow phosphor 123Y is present at a position where the excitation light Ex is condensed, yellow fluorescence is emitted. In addition, in the rotation period in which the reflection section 124 exists at the position where the excitation light Ex is condensed, the excitation light Ex (blue light) is reflected.

Of the yellow fluorescent light incident on the dichroic mirror 105, the P polarized light component is almost completely transmitted, and the S polarized light component is mostly transmitted at a wavelength of about 490nm or more. Further, the blue light converted into P-polarized light is almost entirely transmitted. That is, these lights efficiently transmit through the dichroic mirror 105, are emitted as output light of the light source device, and are appropriately condensed by the condenser lens 109.

The condenser lens 109 is set to a predetermined NA so as to be suitable for the F value of the projection optical system 610, and condenses the illumination light IL to the entrance port of the light tunnel 140. As shown in fig. 1, the output light of the light source device is used as illumination light IL for the projection display device. In some cases, a switching color filter (color wheel) may be provided between the condenser lens 109 and the optical path 140, for example, in order to remove unnecessary spectral components from the illumination light IL.

Next, an illumination optical system that distributes the illumination light IL supplied from the light source apparatus 110 to the reflective light modulation device 200a (first reflective light modulation device) and the reflective light modulation device 200b (second reflective light modulation device) will be described.

Fig. 2 is a diagram showing a part of the illumination optical system according to embodiment 1. The illumination light IL propagated through the light tunnel 140 is shaped by the light tunnel-side condenser lens 150 into light beams suitable for illuminating the reflective light modulation devices 200a and 200b. The light-passage-side condenser lens 150 is constituted by a single lens or a plurality of lenses.

The illumination light IL having passed through the optical path-side condenser lens 150 further passes through the intermediate image-side condenser lens 151 to form an enlarged intermediate image 155. However, the dichroic mirror 180 is disposed near the imaging position of the enlarged intermediate image 155, and the incident angle η 1 of the illumination light IL is set to 27.5 degrees. Red light R contained in illumination light IL is transmitted from dichroic mirror 180, and green light G and blue light B are reflected by dichroic mirror 180. The incident angle η 1 of the illumination light IL is not necessarily 27.5 degrees, and preferably satisfies the following condition:

25 degree < eta 1 < 32 degree \8230; (Condition 1)

Fig. 5 shows the wavelength dependence of the transmittance of the dichroic mirror 180. The plate-shaped dichroic mirror 180 has an advantage that the PS separation width and the angular deviation (incident angle dependency) are small as compared with the cross dichroic prism. As shown in fig. 5, even if the incident angle varies ± 10 degrees from 28 degrees, the angular deviation exists, but the amount of deviation is small. The rising edge of the curve is also steep and almost stepwise, and the visible red light separating ability is excellent.

Red light R transmitted from dichroic mirror 180 is used to illuminate reflective light modulation device 200B, and green light G and blue light B reflected by dichroic mirror 180 are used to illuminate reflective light modulation device 200a. In other words, the first color light component of the amplified intermediate image 155 of the illumination light is transferred to the first reflective light modulator device, and the second color light component is transferred to the second reflective light modulator device. In the following description, the green light G and the blue light B for illuminating the reflective light modulation device 200a are sometimes referred to as first illumination light (G + B), and the red light R for illuminating the reflective light modulation device 200B is sometimes referred to as second illumination light (R). In addition, the optical path of the first illumination light from the dichroic mirror 180 to the reflective light modulation device 200a is referred to as a first illumination optical system, and the optical path of the second illumination light from the dichroic mirror 180 to the reflective light modulation device 200b is referred to as a second illumination optical system.

As can be understood from fig. 1 and 2, in the first illumination optical system, the first illumination light (G + B) reflected by the dichroic mirror 180 is condensed onto the reflective light modulation device 200a via the intermediate image side condenser lens 160 (first lens), the fold-back mirror 182a (first mirror), the modulation device side condenser lens 163, and the TIR prism 170 a. In the first illumination optical system, the first illumination light is reflected at three places, that is, the dichroic mirror 180, the folding mirror 182a, and the TIR prism 170a, between the light source device 110 and the reflective light modulation device 200a, and therefore the number of folding times of the first illumination light is 3 times.

Further, the optical axis of the illumination light IL from the light tunnel 140 to the dichroic mirror 180 is located in a direction parallel to the Y axis, that is, in a first plane parallel to the XY plane, and the optical axis of the first illumination light after being reflected by the dichroic mirror 180 is located in the first plane parallel to the XY plane until reaching the folding back mirror 182 a. On the other hand, after being reflected by the reflecting mirror 182a, the optical axis of the first illumination light deviates from the XY plane and has a Z-direction component. That is, the optical axis of the first illumination light is deflected in the direction intersecting the first plane by the folding mirror 182a in front of the reflective light modulation device 200a.

The TIR prism 170a is, for example, a total internal reflection prism configured by combining two prisms, and causes total internal reflection of the first illumination light to be incident on the reflective light modulation device 200a at a predetermined angle.

As described above, the incident angle η 1 of the illumination light IL incident on the dichroic mirror 180 is set to 27.5 degrees, for example, and the angular difference (sum of the incident angle and the reflection angle) β between the incident light IL and the reflection by the reflecting mirror 182a is set to 59.3 degrees, for example.

On the other hand, the second illumination light (R) transmitted from the dichroic mirror 180 is condensed on the reflective light modulation device 200b via the intermediate image-side condenser lens 161, the optical path changing mirror 181, the relay lens 162 (second lens), the folding mirror 182b (second mirror), the modulation device-side condenser lens 163, and the TIR prism 170 b. In the second illumination optical system, the light is reflected at three places, i.e., the optical path changing mirror 181, the folding mirror 182b, and the TIR prism 170b, between the light source device 110 and the reflective light modulation device 200b, and thus the number of folding times of the second illumination light is 3 times. That is, since the number of times of folding the first illumination light is equal to the number of times of folding the second illumination light, the illumination light of the same quality can be applied to each reflective light modulator, and the occurrence of depth unevenness can be suppressed.

The optical axis of the second illumination light is positioned in the first plane parallel to the XY plane after being transmitted through the dichroic mirror 180 and reflected by the optical path changing mirror 181 until reaching the folding mirror 182b, but after being reflected by the folding mirror 182b, the optical axis deviates from the XY plane and has a Z-direction component. That is, the optical axis of the second illumination light is deflected in the direction intersecting the first plane by the folding mirror 182b in front of the reflective light modulation device 200b.

The TIR prism 170b is, for example, a total internal reflection prism formed by bonding two prisms, and causes the second illumination light to be totally internally reflected and incident on the reflective light modulation device 200b at a predetermined angle.

The incident angle η 2 (fig. 2) at which the second illumination light enters the optical path changing mirror 181 is set to 64 degrees, for example, and the angular difference β between the entrance and reflection (the sum of the incident angle and the reflection angle) at the folding mirror 182b is set to 59.3 degrees, for example, as in the case of the first illumination light. Further, the following relationship is established with respect to the incident angle η 1 of the illumination light IL entering the dichroic mirror 180 and the incident angle η 2 of the second illumination light entering the optical path changing mirror 181.

Eta 2. Gtoreq. Eta.1 \8230; (Condition 2)

In the illumination optical system of the first illumination light and the illumination optical system of the second illumination light, the same specification devices can be used for the folding mirrors 182a and 182b, the modulator-side condenser lens 163, and the TIR prisms 170a and 170b, respectively. In the two illumination optical systems, these optical devices are arranged in such a manner that the relative positional relationship with respect to the reflective light modulation device is equivalent.

Fig. 7 (a) typically shows the illumination optical system from the optical channel 140 to the reflective light modulation device 200a, and fig. 7 (b) typically shows the illumination optical system from the optical channel 140 to the reflective light modulation device 200b. For convenience of illustration, in fig. 7 (a), the change in the optical path direction by the dichroic mirror 180, the folding mirror 182a, and the TIR prism 170a is not illustrated, and the optical axis is illustrated as a straight line. Similarly, in fig. 7 (b), the change of the optical path direction by the optical path changing mirror 181, the folding mirror 182b, and the TIR prism 170b is not illustrated, and the optical axis is illustrated as a straight line.

In addition, fig. 6 typically shows the arrangement of the optical devices when the reflective light modulation device 200b is viewed from the back surface side. In fig. 6, a part of the illumination optical system is not shown. The illumination light directed from the reflection point P of the folding back mirror 182b toward the TIR prism 170b is incident on the reflective light modulation device 200b at an incident angle of 45 °. As described with reference to fig. 15, the DMD device used as the reflective light modulation device 200b (and the reflective light modulation device 200 a) uses a device in which the reflection surface of the micromirror of each pixel is inclined by 45 ° with respect to the frame of the screen when the screen is viewed from above, and the reflection surface is driven in accordance with an image signal to change the reflection direction of the illumination light.

As shown in fig. 7 (a), an intersection of the optical axis of the first illumination light and the dichroic mirror 180 is denoted by S, an intersection of the optical axis of the first illumination light and the folding mirror 182a is denoted by Pa, and a distance between S and Pa is denoted by La. As shown in fig. 7 (b), an intersection of the optical axis of the second illumination light and the dichroic mirror 180 is S, an intersection of the optical axis of the second illumination light and the folding mirror 182b is Pb, and a distance between S and Pb is Lb.

As illustrated in fig. 7 (a) and 7 (b), in the present embodiment, the folding mirror 182a for the first illumination light and the folding mirror 182b for the second illumination light are arranged such that La and Lb are not necessarily equal, that is, la/Lb is not necessarily 1.

For both the first illumination light and the second illumination light, since the optical path lengths from the folding mirror 182a (folding mirror 182 b) to the reflective light modulation device 200a (reflective light modulation device 200 b) are set to be equal, the optical path length of the first illumination light from the optical tunnel 140 to the reflective light modulation device 200a and the optical path length of the second illumination light from the optical tunnel 140 to the reflective light modulation device 200b produce a difference of La-Lb = Δ L. In addition, as a configuration in which La/Lb is not 1, in addition to the configuration in which La > Lb shown in fig. 7 (a) and 7 (b), the folding mirror 182a for the first illumination light and the folding mirror 182b for the second illumination light may be arranged so that La < Lb.

In the present embodiment, in order to make the conditions for illuminating the reflective light modulation device 200a with the first illumination light and the conditions for illuminating the reflective light modulation device 200b with the second illumination light as much as possible coincide, the intermediate image side condenser lens 160 is disposed between the dichroic mirror 180 and the folding mirror 182a in the optical path of the first illumination light, the intermediate image side condenser lens 161 is disposed between the dichroic mirror 180 and the optical path changing mirror 181 in the optical path of the second illumination light, and the relay lens 162 is disposed between the optical path changing mirror 181 and the folding mirror 182b. By appropriately setting the positions and focal lengths of these lenses, the influence of the optical path length difference Δ L can be reduced to make the illumination conditions of the two reflective light modulation devices uniform.

In the present embodiment, as described above, the light source device 110 including the yellow phosphor outputs fluorescence having the spectral characteristics shown in fig. 17, and the dichroic mirror 180 separates color light, and in order to improve the color purity of illumination light, it is preferable to provide the first illumination optical system with the cyan filter CF and the second illumination optical system with the red filter RF. Although the position where the filter is provided is arbitrary, in the present embodiment, a dichroic filter (multilayer film filter) is provided on the emission surface of the modulator-side condenser lens 163 of each optical system in consideration of the symmetry of the optical system. That is, as shown in fig. 7 (a), a cyan filter CF having the characteristics shown in fig. 9 (a) is provided on the emission surface of the modulator-side condenser lens 163 of the first illumination optical system, and as shown in fig. 7 (b), a red filter RF having the characteristics shown in fig. 9 (b) is provided on the emission surface of the modulator-side condenser lens 163 of the second illumination optical system.

Thereby, the reflective light modulation device 200a and the reflective light modulation device 200b are illuminated by the first illumination light and the second illumination light, respectively.

Further, when the optical path length from the dichroic mirror 180 to the reflective light modulation device 200a is given as LDA, and the optical path length from the dichroic mirror 180 to the reflective light modulation device 200b is given as LDB, it is preferable that the following condition is satisfied:

LDA/LDB of 0.9 < 1.1 \8230; (Condition 3)

The reflective light modulation device 200a and the reflective light modulation device 200b have a plurality of micromirrors arranged in an array, and both modulate illumination light in synchronization with the color switching timing of the illumination light IL irradiated from the light source apparatus 110.

Fig. 18 (a) to 18 (e) are timing charts in which the horizontal axis represents time t in order to explain the driving timing of the light source device 110 and each reflective light modulation device. As described with reference to fig. 8 (a), 16, and 17, the light source device 110 rotates the rotary body 122 to alternately output the yellow fluorescent light emitted from the yellow fluorescent material 123Y and the blue light reflected by the reflecting portion 124. If the rotating body 122 is controlled to rotate once in synchronization with one frame period of the image signal, Y light and B light are alternately output from the light source device 110 as shown in (a) of fig. 18.

Since the dichroic mirror 180 has the transmission characteristics shown in fig. 5, the first illumination light reflected by the dichroic mirror 180 is such that the G light and the B light are alternately irradiated as shown in fig. 18 (B), and the second illumination light transmitted through the dichroic mirror 180 is such that the R light is intermittently irradiated as shown in fig. 18 (d).

The image light G + B shown in (c) of fig. 18 is output from the reflective light modulation device 200a by inputting the G component and the B component of the image signal in synchronization with the color switching timing of the first illumination light. In addition, the image light R shown in (e) of fig. 18 is output from the reflective light modulation device 200b by inputting the R component of the image signal in synchronization with the timing of the R light lighting of the second illumination light. The image light of each color is pulse-width modulated by the reflective light modulation device in accordance with the brightness of each color component in the image signal. In the case where the pulse width (time length) equivalent to one gradation needs to be made different for each color, the clock frequency for driving the reflective light modulation device can be adjusted in accordance with the color of the image light.

Next, a projection optical system that synthesizes and projects the image lights output from the reflective light modulation devices 200a and 200b will be described.

Fig. 3 is a diagram in which a part of a projection optical system 610 is extracted from the entire configuration of the projection display device 1 shown in fig. 1 for the purpose of explaining the projection optical system.

As described above, the reflective light modulation device 200a drives the micromirror device according to the signal component of the G color or the B color in the image signal, reflects the first illumination light at a predetermined angle, and outputs the image light G + B shown in (c) of fig. 18. The image light G + B is transmitted from the TIR prism 170a and incident on the first rear group lens 601a, and further transmitted from the synthesis prism 400 and incident on the front group lens 602, and is enlarged and projected onto the projection surface 700 (for example, a projection screen).

The reflective light modulation device 200b drives the micromirror device based on the signal component of the R color in the image signal, reflects the second illumination light at a predetermined angle, and outputs the image light R shown in (e) of fig. 18. The image light R is transmitted through the TIR prism 170b and enters the second rear group lens 601b, and is internally reflected by the combining prism 400, so that the optical path is changed and enters the front group lens 602, and is enlarged and projected onto the projection surface 700 (for example, a projection screen). In fig. 1 to 3, the optical axis LX of the front group lens 602 is indicated by a one-dot chain line.

The front group lens 602 and the first rear group lens 601a function together as a projection lens for the image light G + B. Similarly, the front group lens 602 and the second rear group lens 601b function together as a projection lens for the image light R. Here, the TIR prism 170a and the TIR prism 170b use devices of the same structure, and the first rear group lens 601a and the second rear group lens 601b use lenses of the same structure. As described later, the optical path length of the image light R and the optical path length of the image light G + B are arranged to be equal in the combining prism 400. Therefore, in the projection lens system according to the present embodiment, the adjustment (for example, focus adjustment) of the image on the projection surface 700 can be performed simply by operating the front group lens 602.

The combining prism 400 changes the optical path of the image light R to overlap the optical path of the image light G + B, and guides the image light R and the image light G + B toward the front group lens 602.

As shown in fig. 4 (a), the synthesis prism 400 is composed of three prisms, that is, a prism 401, a prism 402, and a prism 403. The prism 401 is opposed to the prism 402 with an air gap AG1 as a minute gap, and the prism 402 is opposed to the prism 403 with an air gap AG2 as a minute gap. A dielectric multilayer film 405 is provided on a surface of the optical surface of the prism 402 facing the prism 401 with an air gap AG1 therebetween.

The image light R is incident on the prism 402, and then totally internally reflected toward the dielectric multilayer film 405 on the optical surface on the air gap AG2 side. In the present embodiment, the incident angle ω of the image light R with respect to the dielectric multilayer film 405 is configured to ω =12 degrees. The dielectric multilayer film 405 has the transmission/reflection characteristics shown in fig. 4 (b), and substantially all of the image light R is reflected. Further, since the dielectric multilayer film 405 is not sandwiched (bonded) between the prism 401 and the prism 402 without a gap, but is spaced from the prism 401 with an air gap, the PS separation width and the amount of angular deviation shift are small compared to a bonded cross prism, and the rising edge of the curve in the graph is steep and almost stepwise. The image light R reflected by the dielectric multilayer film 405 is transmitted through the air gap AG2 and the prism 403 and enters the front group lens 602.

On the other hand, the image light G + B is transmitted from the prism 401 and the air gap AG1, and is incident on the dielectric multilayer film 405 at an incident angle of 12 degrees. As is apparent from the transmission/reflection characteristics of fig. 4 (B) described above, the image light G + B is transmitted through the dielectric multilayer film 405. Image light G + B is further transmitted from prism 402, air gap AG2, and prism 403 to be incident on front group lens 602.

Further, the incident angle with respect to the dielectric multilayer film 405 is configured to be substantially equal in the image light R and the image light G + B, excluding manufacturing errors. The shapes of the prism 402 and the prism 401 are set so that the optical path length from the time when the image light R enters the prism 402 to the time when the image light G + B reaches the dielectric multilayer film 405 is equal to the optical path length from the time when the image light G + B enters the prism 401 to the time when the image light G + B exits.

According to the present embodiment described above, for example, the back focal length of the projection lens can be reduced as compared with the two-panel display device disclosed in patent document 1, and therefore the device can be downsized. Further, since a reflective light modulator device of the type in which the micromirrors are arranged in a direction of 45 degrees with respect to the vertical direction (V direction) of the screen is used, it is advantageous in terms of cost. In addition, compared to the two-panel display device disclosed in patent document 2, since an optical system using a cross dichroic prism whose polarization characteristics greatly change depending on the incident angle is not used, it is possible to display a high-quality image having uniform color depth. That is, according to the present embodiment, a two-panel type projection display device having high versatility and a good balance between high image quality, downsizing, and low cost can be realized.

[ embodiment 2]

Next, a projection display device according to embodiment 2 will be described. Note that, for the same or similar portions as those in embodiment mode 1, description thereof is simplified or omitted.

Fig. 10 is a typical view showing an optical configuration of a projection display device according to embodiment 2. The projection display apparatus 2 includes a reflective light modulation device 200a (first reflective light modulation device) and a reflective light modulation device 200b (second reflective light modulation device). In this embodiment, as in embodiment 1, a DMD in which micromirror devices are arranged in an array is used as the reflective light modulation devices 200a and 200b. As described with reference to fig. 15, the DMD is a device in which the reflection surface of each pixel micromirror is inclined by 45 ° with respect to the frame of the screen when the screen is viewed from above, and the reflection surface is driven in accordance with an image signal to change the reflection direction of the illumination light. The micromirrors corresponding to the respective pixels are driven according to the brightness levels of the image signals so that the reflection directions are changed by pulse width modulation.

The projection display device 2 includes a light source device 110. The light source device 110 is a light source for illuminating the reflective light modulation device 200a and the reflective light modulation device 200b.

Fig. 8 (b) shows a structure of the light source device 110 used in the present embodiment. The light source device 110 of the present embodiment does not excite a phosphor to emit light as in the light source device of embodiment 1, but synthesizes output light of solid-state light sources (for example, semiconductor lasers or LEDs of R, G, and B) of different color lights, which can be independently driven, and outputs the synthesized light as illumination light IL. That is, the light source device 110 includes the solid-state light source 111R that emits red light, the solid-state light source 112B that emits blue light, the solid-state light source 113G that emits green light, and the lens 115 that condenses light from the light emitting sources, and emits the illumination light IL to the light tunnel 140 via the condensing lens 109 by overlapping optical paths of the color lights using the dichroic mirror 807 that reflects blue light and the dichroic mirror 808 that reflects red light. By using a solid-state light source (for example, a semiconductor laser or an LED), the illumination light IL having a higher color purity can be emitted to the light tunnel 140 than the fluorescent material in the present embodiment.

Fig. 11 is a diagram showing a part of the illumination optical system according to embodiment 2, and corresponds to fig. 2 in embodiment 1. The basic structure of the illumination optical system in this embodiment is similar to that in embodiment 1, but the installation angle and position of each optical device are different as shown in the table in the figure. In the present embodiment, in order to make the condition for illuminating the reflective light modulation device 200a with the first illumination light and the condition for illuminating the reflective light modulation device 200b with the second illumination light as much as possible coincide, the intermediate image side condenser lens 160 is disposed between the dichroic mirror 180 and the folding mirror 182a in the optical path of the first illumination light, the intermediate image side condenser lens 161 is disposed between the dichroic mirror 180 and the optical path changing mirror 181 in the optical path of the second illumination light, and the relay lens 162 is disposed between the optical path changing mirror 181 and the folding mirror 182b. By appropriately setting the positions and focal lengths of these lenses, the influence of the optical path length difference Δ L can be reduced to make the illumination conditions of the two reflective light modulator devices uniform.

In addition, fig. 14 typically shows the arrangement of the optical devices when the reflective light modulation device 200b is viewed from the back surface side. In fig. 14, a part of the illumination optical system is not shown. The illumination light directed from the reflection point P of the folding back mirror 182b toward the TIR prism 170b is incident on the reflective light modulation device 200b at an incident angle of 45 °. As described with reference to fig. 15, the DMD device used as the reflective light modulation device 200b (and the reflective light modulation device 200 a) uses a device in which the reflection surface of the micromirror of each pixel is inclined by 45 ° with respect to the frame of the screen when the screen is viewed in plan, and the reflection surface is driven in accordance with an image signal to change the reflection direction of the illumination light.

The reflective light modulation device 200a and the reflective light modulation device 200b have a plurality of micromirrors arranged in an array, and both modulate the illumination light in synchronization with the color switching timing of the illumination light IL irradiated from the light source apparatus 110.

Fig. 19 (a) to 19 (e) are timing charts in which the horizontal axis represents time t in order to explain the driving timing of the light source device 110 and each reflective light modulation device. As described with reference to fig. 8 (B), the light source device 110 includes, as solid-state light sources of different color light that can be independently driven, a solid-state light source 111R that emits red light, a solid-state light source 112B that emits blue light, and a solid-state light source 113G that emits green light. As shown in fig. 19 (a), in a period corresponding to one frame of the image signal, for example, about 2/3 of the solid-state light source 111R and the solid-state light source 113G emitting green light are simultaneously turned on to output R light and G light, and the remaining about 1/3 of the solid-state light source 112B is turned on to output B light.

Since the dichroic mirror 180 has the transmission characteristic shown in fig. 5, the first illumination light reflected by the dichroic mirror 180 is such that the G light and the B light are alternately irradiated as shown in fig. 19 (B), and the second illumination light transmitted from the dichroic mirror 180 is such that the R light is intermittently irradiated as shown in fig. 19 (d).

The image light G + B shown in (c) of fig. 19 is output from the reflective light modulation device 200a by inputting the G component and the B component of the image signal in synchronization with the color switching timing of the first illumination light. In addition, the image light R shown in (e) of fig. 19 is output from the reflective light modulation device 200b by inputting the R component of the image signal in synchronization with the timing of the R light lighting of the second illumination light. The image light of each color is pulse-width modulated by the reflective light modulation device in accordance with the brightness of each color component in the image signal. In the case where the pulse width (time length) equivalent to one gradation needs to be made different for each color, the clock frequency for driving the reflective light modulation device can be adjusted in accordance with the color of the image light.

The driving timing is not limited to the example shown in fig. 19 (a) to 19 (e), and may be, for example, the form shown in fig. 20 (a) to 20 (e). As shown in fig. 20 (a), the solid-state light source 111R is turned on to output R light over the entire range corresponding to the period of one frame of the image signal, and at the same time, the solid-state light source 113G emitting green light is turned on to output G light, and the solid-state light source 112B is turned on to output B light, for example, about 2/3 of the period corresponding to one frame of the image signal.

Since the dichroic mirror 180 has the transmission characteristics shown in fig. 5, the first illumination light reflected by the dichroic mirror 180 is such that the G light and the B light are alternately irradiated as shown in fig. 20 (B), and the second illumination light transmitted through the dichroic mirror 180 is such that the R light is continuously irradiated as shown in fig. 20 (d).

The image light G + B shown in (c) of fig. 20 is output from the reflective light modulation device 200a by inputting the G component and the B component of the image signal in synchronization with the color switching timing of the first illumination light. In addition, the image light R shown in (e) of fig. 20 is output from the reflective light modulation device 200b by inputting the R component of the image signal in synchronization with the switching timing of the frame. The image light of each color is pulse-width modulated by the reflective light modulation device in accordance with the brightness of each color component in the image signal. In the case where the pulse width (time length) equivalent to one gradation needs to be made different for each color, the clock frequency for driving the reflective light modulation device can be adjusted in accordance with the color of the image light.

Next, a projection optical system that synthesizes and projects the image lights output from the reflective light modulation devices 200a and 200b will be described.

Fig. 12 is a diagram in which a part of a projection optical system 610 is extracted from the entire configuration of the projection display device 2 shown in fig. 10 for the purpose of explaining the projection optical system.

As described above, the reflective light modulation device 200a drives the micromirror device according to the signal component of the G color or the B color in the image signal, reflects the first illumination light at a predetermined angle, and outputs the image light G + B shown in fig. 19 (c) or fig. 20 (c). The image light G + B is transmitted from the TIR prism 170a and enters the first relay lens 611a, and is further transmitted from the synthesis prism 410 and forms an intermediate image 613 via the third relay lens 612. The intermediate image 613 is enlarged and projected onto a projection surface 700 (for example, a projection screen) by a projection lens 614 disposed on the enlargement side.

The reflective light modulation device 200b drives the micromirror device based on the signal component of the R color in the image signal, reflects the second illumination light at a predetermined angle, and outputs the image light R shown in fig. 19 (e) or 20 (e). The image light R is transmitted through the TIR prism 170b and enters the second relay lens 611b, is internally reflected by the combining prism 410 to change the optical path, and forms an intermediate image 613 through the third relay lens 612. The intermediate image 613 is projected on the projection surface 700 (for example, a projection screen) in an enlarged manner by the projection lens 614.

As described above, the present embodiment differs from embodiment 1 in that it has the following configuration: an intermediate image of the display image is temporarily formed in front of the projection lens 614 using a relay lens. In the present embodiment, since the beam diameter near the stop of the relay lens can be reduced, the size of the combining prism 410 can be reduced.

The combining prism 410 changes the optical path of the image light R to overlap the optical path of the image light G + B, and guides the image light R and the image light G + B toward the front group lens 602.

As shown in fig. 13 (a), the combining prism 410 is composed of two prisms, i.e., a prism 411 and a prism 412. The prism 411 and the prism 412 are opposed to each other with an air gap AG3 as a minute gap therebetween. A dielectric multilayer film 415 is provided on a surface of the optical surface of the prism 411 facing the prism 412 with an air gap AG3 therebetween.

The image light R enters the prism 411 and is totally internally reflected toward the dielectric multilayer film 415 on the optical surface on the third relay lens 612 side. In the present embodiment, the incident angle ω of the image light R with respect to the dielectric multilayer film 415 is configured to ω =26.5 degrees. The dielectric multilayer film 415 has transmission/reflection characteristics shown in fig. 13 (b), and substantially all of the image light R modulated by the illumination light having good monochromaticity of the solid-state light source is reflected. Further, since the dielectric multilayer film 415 is not sandwiched (bonded) between the prisms 411 and 412 without a gap, but is spaced from the prisms 412 with an air gap therebetween, the PS separation width and the amount of angular deviation shift are small compared to a bonded cross prism, and the rising edge of the curve in the graph is steep and almost stepwise. The image light R reflected by the dielectric multilayer film 415 is transmitted from the prism 411 and enters the third relay lens 612.

On the other hand, the image light G + B is transmitted from the prism 412 and the air gap AG3, and enters the dielectric multilayer film 415 at an incident angle of 26.5 degrees. As is apparent from the transmission/reflection characteristics of fig. 13 (B) described above, the image light G + B modulated by the illumination light having good monochromaticity of the solid-state light source is transmitted through the dielectric multilayer film 415. The image light G + B further transmits from the prism 411 to enter the third relay lens 612.

Further, the incident angle with respect to the dielectric multilayer film 415 is configured to be equal in the image light R and the image light G + B. The shapes of the prism 411 and the prism 412 are set so that the optical path length from the time when the image light R enters the prism 411 to the time when the image light G + B reaches the dielectric multilayer film 415 is equal to the optical path length from the time when the image light G + B enters the prism 412 to the time when the image light G + B is emitted.

According to the present embodiment described above, for example, the back focal length of the projection lens can be reduced as compared with the dual panel display device disclosed in patent document 1, and therefore the device can be downsized. Further, since a reflective light modulator device of the type in which the micromirrors are arranged in a direction of 45 degrees with respect to the vertical direction (V direction) of the screen is used, it is advantageous in terms of cost. In addition, compared to the two-panel display device disclosed in patent document 2, since an optical system using a cross dichroic prism whose polarization characteristics greatly change depending on the incident angle is not used, it is possible to display a high-quality image having uniform color depth. That is, according to the present embodiment, a two-panel type projection display device having high versatility and a good balance between high image quality, downsizing, and low cost can be realized.

[ other embodiments ]

The implementation of the present invention is not limited to the above-described embodiments or specific examples, but various modifications may be made within the technical idea of the present invention.

For example, the light source device used in embodiment 1 may be combined with the projection optical system for forming an intermediate image used in embodiment 2. Alternatively, the light source device used in embodiment 2 may be combined with the projection optical system used in embodiment 1, which does not form an intermediate image.

In embodiment 1, the incident angle ω of the first image light (R + G) and the second image light (R) incident on the dielectric multilayer film 405 of the combining prism 400 is set to a substantially equal magnitude except for a manufacturing error, and is set to ω =12 degrees. In embodiment 2, the incident angle ω of the first image light (R + G) and the second image light (R) incident on the dielectric multilayer film 415 of the combining prism 410 is set to a substantially equal magnitude except for a manufacturing error, and is set to ω =26.5 degrees. In the practice of the present invention, the incident angle ω is not limited to 12 degrees or 26.5 degrees, and the incident angle ω is set in a range of 10 degrees or more and 27 degrees or less.

For example, although the screen may be often used in combination with a projection display device as a component of a projection display system, the embodiment of the present invention is not limited thereto. As described above, the projection display device according to the embodiment is also suitable for portable use because the operation for optically adjusting the display image is simple, and can easily project the display image on an arbitrary surface of an arbitrary place such as a wall of a building where no screen is provided.

Claims (7)

1. A projection display device is characterized by comprising:

a light source;

a light tunnel for propagating light from the light source along an optical axis disposed in a first plane;

a dichroic mirror that splits light from the light source incident via the light channel into first illumination light of first color light and second illumination light of second color light;

a first illumination optical system that guides the first illumination light reflected by the dichroic mirror to a first reflective light modulation device;

a second illumination optical system that guides the second illumination light transmitted from the dichroic mirror to a second reflective light modulation device;

a combining prism that transmits the first image light output from the first reflective light modulation device through a dielectric multilayer film, reflects the second image light output from the second reflective light modulation device through the dielectric multilayer film to change an optical path, and emits combined light obtained by combining the first image light and the second image light;

a first rear group lens which is arranged between the synthesis prism and the first reflection type light modulation device and acts on the first image light;

a second rear group lens which is arranged between the synthesis prism and the second reflection type light modulation device and acts on the second image light; and

a front group lens which is arranged closer to the magnifying side than the synthesis prism and acts on the synthesis light,

the incident angles of the first image light and the second image light to the medium multilayer film are equal in magnitude and are 10 degrees or more and 27 degrees or less.

2. The projection display device of claim 1,

the first rear group lens, the second rear group lens and the front group lens form a projection lens system,

the first image light is projected in an enlarged manner through the first rear group lens and the front group lens, and the second image light is projected in an enlarged manner through the second rear group lens and the front group lens.

3. The projection display device of claim 1,

the first rear group lens constitutes a first relay lens,

the second rear group lens constitutes a second relay lens,

the front group lens includes: a third relay lens arranged on the synthesis prism side; and a projection lens arranged on the enlargement side,

the first image light forms an intermediate image between the third relay lens and the projection lens through the first relay lens and the third relay lens,

the second image light forms an intermediate image between the third relay lens and the projection lens through the second relay lens and the third relay lens,

the intermediate image of the first image light and the second image light is projected in an enlarged manner through the projection lens.

4. The projection display device according to any one of claims 1 to 3,

the first illumination optical system includes: a first reflecting mirror deflecting an optical axis of the first illumination light in a direction crossing the first plane in front of the first reflective light modulation device,

the second illumination optical system includes: an optical path changing mirror for deflecting an optical axis of the second illumination light in the first plane; and a second mirror deflecting an optical axis of the second illumination light in a direction intersecting the first plane in front of the second reflective light modulation device,

when the optical path length from the dichroic mirror to the first reflective light modulation device is set to LDA, and the optical path length from the dichroic mirror to the second reflective light modulation device is set to LDB,

the LDA/LDB is more than 0.9 and less than 1.1.

5. The projection display device according to claim 4,

when an incident angle at which light from the light source is made incident on the dichroic mirror is defined as η 1,

satisfy 25 < eta 1 < 32 degrees.

6. The projection display device of claim 5,

when the incident angle of the second illumination light to the optical path changing mirror is defined as η 2,

eta 2 is more than or equal to eta 1.

7. The projection display device according to any one of claims 1 to 6,

and a condensing lens that forms an intermediate image of the light from the light source is provided between the light tunnel and the dichroic mirror, the first illumination optical system transfers a first color light component of the intermediate image to the first reflective light modulation device, and the second illumination optical system transfers a second color light component of the intermediate image to the second reflective light modulation device.

Images