CN115327842A - A projection display device - Google Patents

Abstract

A projection display device with high image quality, miniaturization and low cost, comprising: a dichroic mirror for dividing light from a light source into first illumination light of a first color light and second illumination light of a second color light; an illumination optical system for guiding the first illumination light to the first reflective light modulation device; a second illumination optical system for guiding the second illumination light to the second reflective light modulation device; The first image light output from the light modulation device is transmitted through the dielectric multilayer film, and the second image light output from the second reflective light modulation device is reflected by the dielectric multilayer film to change the optical path, and emits the first image light and the second image light. The combined light after the two image lights are combined; the first rear group lens; the second rear group lens; The magnitudes of the incident angles to the dielectric multilayer film are substantially equal to 10 degrees or more and 27 degrees or less.

Description

A projection display device

technical field

The present invention relates to a double-panel projection display device provided with two reflective light modulation devices.

Background technique

Conventionally, there is known a projection display device that includes a light modulation device such as a digital micromirror device (DMD, a liquid crystal device), and a projection optical system, and magnifies and projects a color image onto a screen or the like for display.

For example, a single-panel type projection display device is known, which irradiates a single-panel light modulation device while switching illumination lights of different colors at a high speed, and projects images of different colors in time division. Although the light modulation device is a single board, it can also display in color, so it is advantageous in terms of cost reduction and device miniaturization, but it is difficult to achieve high brightness because it is displayed while switching images of different display colors in time division. In addition, when a switchable color filter is used in combination with a white light source in order to generate illumination light whose color is time-division switched, only a part of the white light is used, and there is also a problem of increased power consumption due to low light utilization efficiency. The problem.

As a method different from the single-plate type, a three-plate type projection display device is known, which includes three light modulators, and illuminates lights of different colors (for example, red (R), green (G), blue ( b)) Irradiating each light modulation device, using a cross dichroic prism or the like to synthesize and project display images of different colors output from each light modulation device. Compared with the above-mentioned single-plate type, it can achieve higher brightness, so it is suitable for large-screen applications such as movies. However, due to the complicated structure of the optical system and the large number of parts, it is difficult to achieve cost reduction and device miniaturization. Use is restricted.

Therefore, in order to realize a device with high versatility that is excellent in the balance between high luminance, miniaturization, and cost reduction, a two-panel projection display device including two light modulators has been tried.

For example, Patent Document 1 discloses a projection display device comprising: a light source unit; a dichroic mirror for separating light emitted from the light source unit into a first color light and a second color light; The first color light is modulated; the second light modulation device is used to modulate the second color light; and the color synthesis prism is used to modulate the first color light modulated by the first light modulation device and the first color light modulated by the second light modulation device. Dichroic light for color synthesis. The device also includes a projection unit for projecting the synthesized light emitted from the color synthesis prism.

In addition, Patent Document 2 discloses a projection display device comprising: a polarizing cross dichroic prism for separation, which separates light from a light source unit; a first light modulation device and a second light modulation device; The cross dichroic prism synthesizes the output light of the first light modulation device and the output light of the second light modulation device. The light source assembly of the device is configured to irradiate blue light to the first light modulation device and the second light modulation device respectively during the first display period, irradiate green light to the first light modulation device during the second display period, and irradiate green light to the second light modulation device during the first display period. The light modulation device irradiates red light.

Patent Document 1: Japanese Patent Laid-Open No. 2018-146951

Patent Document 2: International Publication No. 2018/073893

In the method described in Patent Document 1, when the angle of incidence to the dichroic mirror is θ1 and the angle of incidence to the color synthesis prism is θ2, the angles are set as θ1 = 55 degrees and θ2 = 35 degrees. And lay out the optics. As shown in Figure 1 of this document, the prism assembly that integrates the total internal reflection (TIR, Total Internal Reflection) prism and the color synthesis prism is arranged between the light modulation device and the projection lens, and will be used for the color synthesis prism The incident angle θ2 is set to 35 degrees, so that the back focus of the projection lens becomes larger than that of the three-plate type. In this sense, the miniaturization of the device may not be sufficient.

In addition, in Patent Document 1, the miniaturization of the device is achieved by arranging the light modulator in a symmetrical manner with respect to the color synthesis plane of the color synthesis prism, but as a result of setting θ2 = 35 degrees as described above, it is difficult The most popular and cost-effective type of reflective light modulation device is used. As shown in Fig. 15, the most popular and cost-effective reflective light modulation device is the following type: a plurality of micromirrors are arranged two-dimensionally on the screen, and each micromirror can be turned on/off (on/off) The reflection surface is driven with an inclination of ±12 degrees. In this device, the on light to be displayed and the off light not to be displayed are reflected in different directions as enlarged in the upper left corner of the figure, but in the device of Patent Document 1, θ2 = 35 degrees and are arranged symmetrically As a result of the light modulating device, a geometric configuration that reflects on light toward the projection lens and off light toward the outside of the projection lens cannot be established. Therefore, when implementing the method described in Patent Document 1, it is not possible to use a cost-effective type of reflective light modulation device, but it is necessary to use a micromirror whose off-angle direction is the horizontal direction (H direction) or vertical direction of the screen. (V direction) reflective light modulation device.

In addition, in the method described in Patent Document 2, a polarizing cross dichroic prism is used as means for color combining the output lights of two light modulation devices, but the polarization characteristics of the cross dichroic prism vary greatly depending on the incident angle. Variety. Therefore, for example, in an actual optical system with an F value of about 2.5 and an in-plane incidence angle deviation of ±12 degrees, color unevenness (color mottle) occurs remarkably within the display screen, resulting in a problem of degraded display quality.

Therefore, there is a need for a dual-plate projection display device with high versatility that achieves a good balance between high image quality with uniform color depth (less color spots), miniaturization, and low cost.

Contents of the invention

One aspect of the present invention is a projection display device, characterized in that it comprises: a light source; an optical channel for propagating light from the light source along an optical axis arranged on a first plane; a dichroic mirror for transmitting light through the The light from the light source incident on the light channel is divided into the first illumination light of the first color light and the second illumination light of the second color light; the first illumination optical system will be reflected by the dichroic mirror The first illumination light is guided to the first reflective light modulation device; the second illumination optical system guides the second illumination light transmitted from the dichroic mirror to the second reflective light modulation device; the synthesis prism makes the The first image light output from the first reflective light modulation device is transmitted through the dielectric multilayer film, and the second image light output from the second reflective light modulation device is reflected by the dielectric multilayer film. Changing the optical path to emit the synthesized light after combining the first image light and the second image light; the first rear group lens is arranged between the synthesis prism and the first reflective light modulation device, and functions on the first image light; the second rear group of lenses is arranged between the synthesis prism and the second reflective light modulation device, and acts on the second image light; and the front group of lenses is arranged on the Closer to the magnification side than the synthesis prism, and acting on the synthesis light, the incident angles of the first image light and the second image light to the dielectric multilayer film are substantially equal to 10 degrees Above and below 27 degrees.

According to the present invention, it is possible to provide a highly versatile dual-panel projection display device that achieves a good balance between high image quality with uniform color shades, miniaturization, and low cost.

Description of drawings

FIG. 1 is a typical diagram showing an optical configuration of a projection display device according to Embodiment 1. As shown in FIG.

FIG. 2 is an extracted and displayed view of a part of the illumination optical system in Embodiment 1. FIG.

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 the properties of the dielectric multilayer film 405.

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

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

(a) of FIG. 7 is a diagram typically showing the illumination optical system from the light channel 140 to the reflective light modulation device 200a; (b) of FIG. 200b is a diagram of the illumination optics.

8( a ) is a diagram showing the configuration of the light source device 110 used in Embodiment 1; FIG. 8( b ) is a diagram showing the configuration 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 diagram showing an optical configuration of a projection display device according to Embodiment 2. FIG.

FIG. 11 is an extracted and displayed view of a part of the illumination optical system in Embodiment 2. FIG.

FIG. 12 is a diagram showing a projection optical system in Embodiment 2. FIG.

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

Fig. 14 is a diagram showing the arrangement of each optical device when viewing the reflective light modulation device 200b from the rear side in Embodiment 2.

FIG. 15 is a diagram for explaining the structure of a reflective light modulation device.

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

FIG. 17 is a graph showing the emission characteristics of phosphors (fluorescent materials).

(a) of FIG. 18 is a timing chart showing the color lights of the illumination light IL output from the light source device 110 according to the first embodiment; (b) of FIG. 18 shows the first illumination light according to the first embodiment. Timing chart of colored light; (c) of FIG. Timing chart of color light of second illumination light; (e) of FIG. 18 is a timing chart showing image light output from reflective light modulation device 200 b according to Embodiment 1.

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

(a) of FIG. 20 is a timing chart showing the color lights of the illumination light IL output from the light source device 110 according to Embodiment 2; (b) of FIG. 20 is a diagram showing the first illumination light according to Embodiment 2. Timing chart of colored light; (c) of FIG. 20 is a timing chart showing image light output from the reflective light modulation device 200a according to Embodiment 2; (d) of FIG. Timing chart of color light of second illumination light; (e) of FIG. 20 is a timing chart showing image light output from reflective light modulation device 200 b according to Embodiment 2. FIG.

Explanation of reference signs

1...Projection display device

110...Light source device

105……Dichroic mirror

107...1/4 wavelength plate

109...Concentrating lens

111R... Solid light source emitting red light

112B... solid light source emitting blue light

113G... solid light source emitting green light

121...Motor

122...rotating body

123... Phosphor

123Y...Yellow Phosphor

124...Reflection Department

140... Optical channel

150...Concentrating lens on the light channel side

151...Concentrating lens on the intermediate image side

155...Enlarge the intermediate image

160……Intermediate image side condenser lens

161...Concentrating lens on the intermediate image side

162...Relay lens

163...Condenser lens on modulation device side

170a, 170b... TIR prism

180...Dichroic mirror

181... Optical path change reflector

182a, 182b... Folding mirrors

200a, 200b...reflective optical modulation device

210...Excitation light source components

400...Synthetic Prisms

401, 402, 403... Prisms

405...Dielectric multilayer film

410...Synthetic Prism

411, 412... Prisms

415...Dielectric multilayer film

601a...the first rear lens group

601b...The second rear group lens

602...Front lens

610...Projection optical system

611a...the first relay lens

611b...second relay lens

60...Projection optical system

612...The third relay lens

613...Intermediate image

614...Projection lens

700...projection surface

AG1, AG2, AG3...Air gap

Ex...excitation light

IL...illumination light

LX... the optical axis of the front group lens

Detailed ways

Next, the projection display device according to the embodiment will be described with reference to the drawings.

[Embodiment 1]

FIG. 1 is a typical diagram showing an optical configuration of a projection display device according to Embodiment 1. As shown in FIG. The projection display device 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 this embodiment, as the reflective light modulation device 200a and the reflective light modulation device 200b, a DMD having micromirror devices arranged in an array is used. Among them, as described with reference to FIG. 15, as the DMD, when the screen is viewed from above, the reflective surface of the micromirror of each pixel is inclined by 45° with respect to the frame of the screen, and the reflective surface is driven according to the image signal to change the reflection direction of the illumination light. . The micromirror corresponding to each pixel is driven according to the brightness level of the image signal so that the reflection direction is 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. (a) of FIG. 8 shows the structure of the light source device 110 used in this embodiment. The light source device 110 includes an excitation light source module 210. The excitation light source module 210 is a module in which a plurality of light emitting devices (such as semiconductor lasers emitting blue light) are arranged two-dimensionally and a collimator lens is provided corresponding to each light emitting device. In addition, the light source device 110 includes a rotating body 122 rotatable by a motor 121 , and a phosphor (fluorescent material) 123 is provided on a main surface of the rotating body 122 . Furthermore, a dichroic mirror 105 , a 1/4 wavelength plate 107 , and a condenser lens are arranged between the excitation light source unit 210 and the phosphor 123 .

In the light source device of this embodiment, the rotating body 122 is rotatable by the motor 121, and the phosphor 123 is provided on the main surface of the rotating body 122. 16 shows a top view of the rotating body 122. On the main surface of the rotating body 122, a yellow phosphor 123Y is coated on a part of an annular region centered on the rotating axis RA, and is not coated on the rest of the annular region. Instead of phosphors, reflectors 124 for reflecting excitation light Ex are provided. The reflection part 124 is preferably mirror-finished in advance so as to efficiently reflect the blue laser light. On the base of the region where the yellow fluorescent substance 123Y is provided, there is provided a reflective surface for reflecting the fluorescent light radiated in the direction of the rotating body 122 to the lens side 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 yellow phosphor 123Y is irradiated with excitation light Ex. Graph 32 shown by a dashed-dotted line in the figure is the emission spectrum of the yellow phosphor 123Y. For reference, Fig. 31 shows the emission spectrum of a general green phosphor with a dotted line graph, and Fig. 33 shows the emission spectrum of a general red phosphor with a solid line graph. In addition, the peak observed around a wavelength of 450 nm is not light emitted by the phosphor, but light in which a part of the excitation light Ex is not absorbed by the phosphor and is reflected. In addition, the graph 32 shown in Fig. 17 is an example, and the emission characteristics of the phosphors that can be used in the present embodiment do not have to be strictly consistent with it.

By rotating such a rotator 122, the excitation light Ex irradiates either the yellow phosphor 123Y or the reflector 124. In order to prevent the fluorescent body from overheating, the base material of the rotating body 122 is preferably made of a metal with high thermal conductivity. In order to improve the air cooling efficiency, sometimes concave-convex parts or holes are provided on the base material.

Next, the function 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 unit 210 enters the dichroic mirror 105 . S-polarized blue light (excitation light Ex) is reflected by the dichroic mirror 105 toward the rotating body 122. The excitation light passing through the 1/4 wavelength plate 107 is condensed onto the rotating body 122 by the condensing lens.

In the rotation period in which the yellow phosphor 123Y exists at the position where the excitation light Ex is condensed, yellow fluorescence is emitted. In addition, in the rotation period in which the reflection portion 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, almost all of the P-polarized components are transmitted, while most of the S-polarized components with a wavelength of about 490 nm or more are transmitted. In addition, almost all blue light converted into P-polarized light is transmitted. That is, these lights are efficiently transmitted through the dichroic mirror 105, emitted as output light of the light source device, and appropriately condensed by the condensing lens 109.

The condensing lens 109 is set to a predetermined NA to suit the F number of the projection optical system 610, and condenses the illumination light IL to the entrance of the light tunnel 140. As shown in Fig. 1, the output light of the light source device is used as illumination light IL of the projection display device. In addition, depending on circumstances, for example, a switchable color filter (color wheel) may be provided between the condenser lens 109 and the light channel 140 in order to exclude unnecessary spectral components from the illumination light IL.

Next, the illumination optical system that distributes the illumination light IL supplied from the light source device 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) is performed. illustrate.

FIG. 2 is an extracted and displayed view of a part of the illumination optical system according to Embodiment 1. FIG. The illumination light IL propagating through the light channel 140 is shaped by the light channel side condenser lens 150 into a light beam suitable for illuminating the reflective light modulation device 200a and the reflective light modulation device 200b. The light passage side condensing lens 150 is composed of a single or a plurality of lenses.

The illumination light IL passing through the light passage 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 arranged near the imaging position of the enlarged intermediate image 155, and the incident angle η1 of the illumination light IL is set to 27.5 degrees. The red light R contained in the illumination light IL is transmitted from the dichroic mirror 180, and the green light G and the blue light B are reflected by the dichroic mirror 180. In addition, the incident angle η1 of the illumination light IL does not have to be 27.5 degrees, and preferably satisfies the following conditions:

25 degrees <η1<32 degrees... (Condition 1)

FIG. 5 shows the wavelength dependence of the transmittance of the dichroic mirror 180 . Compared with the cross dichroic prism, the plate dichroic mirror 180 has the advantages of small PS separation width and angular shift (incident angle dependence). As shown in Figure 5, even if the incident angle changes by ±10 degrees relative to 28 degrees, the angular offset exists, but the offset is small. In addition, the rising edge of the curve is steep and almost step-like, and the separation capability of visible red light is excellent.

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

As can be understood from FIGS. 1 and 2, in the first illumination optical system, the first illumination light (G+B) reflected by the dichroic mirror 180 passes through the intermediate image side condenser lens 160 (first lens ), the turning mirror 182a (first mirror), the modulation device side condenser lens 163, and the TIR prism 170a to be condensed onto the reflective light modulation device 200a. In the first illumination optical system, the first illumination The number of retracements of light is 3 times.

In addition, the optical axis of the illumination light IL from the light channel 140 to the dichroic mirror 180 is located in the direction parallel to the Y axis, that is, in the first plane parallel to the XY plane, and the optical axis of the first illumination light is dichroic. The mirror 180 is located in a first plane parallel to the XY plane until it reaches the return mirror 182a after reflection. On the other hand, after being reflected by the folding 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 a direction intersecting the first plane by the turning mirror 182a in front of the reflective light modulation device 200a.

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

In addition, the incident angle η1 of the illumination light IL to the dichroic mirror 180 is set to, for example, 27.5 degrees as described above, and the angle difference between the incident and reflected angles (the sum of the incident angle and the reflected angle) β in the folding mirror 182a is, for example, Set to 59.3 degrees.

On the other hand, the second illumination light (R) transmitted from the dichroic mirror 180 passes through the intermediate image side condenser lens 161, the optical path changing mirror 181, the relay lens 162 (second lens), and the return mirror 182b (the second lens). two reflecting mirrors), the modulation device side condenser lens 163, and the TIR prism 170b to condense light onto the reflective light modulation device 200b. In the second illumination optical system, since the light path changing mirror 181, the turning mirror 182b, and the TIR prism 170b are reflected at three places between the light source device 110 and the reflective light modulation device 200b, the second illumination The number of retracements of light is 3 times. That is, since the number of times of retracing of the first illuminating light is equal to that of the second illuminating light, homogeneous illuminating light can be irradiated to each reflective light modulation device, and occurrence of unevenness in shade can be suppressed.

After being transmitted from the dichroic mirror 180, the optical axis of the second illumination light is reflected by the optical path changing mirror 181 until it reaches the turning mirror 182b. After that, 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 a direction intersecting the first plane by the turning mirror 182b in front of the reflective light modulation device 200b.

The TIR prism 170b is, for example, an internal total reflection prism formed by adhering two prisms, and causes internal total reflection of the second illumination light to enter the reflective light modulation device 200b at a predetermined angle.

In addition, the incident angle η2 (FIG. 2) at which the second illumination light is incident on the optical path changing reflector 181 is set to, for example, 64 degrees, and the angle difference between the incident and reflected in the turning reflector 182b (the sum of the incident angle and the reflected angle) β Like the first illumination light, it is set to 59.3 degrees, for example. In addition, the incident angle η1 of the illumination light IL to the dichroic mirror 180 and the incident angle η2 of the second illumination light to the optical path changing mirror 181 are set so that the following relationship holds.

η2≥η1...(Condition 2)

In the illumination optical system of the first illumination light and the illumination optical system of the second illumination light, the turning mirror 182a and the turning mirror 182b, the modulation device side condenser lens 163, the TIR prism 170a and the TIR prism 170b can respectively use the same specifications. device. In these 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.

(a) of FIG. 7 typically shows the illumination optical system from the light channel 140 to the reflective light modulation device 200a, and (b) of FIG. 7 typically shows the illumination optics from the light channel 140 to the reflective light modulation device 200b. system. In addition, for convenience of illustration, in (a) of FIG. 7 , the change of the optical path direction by the dichroic mirror 180, the folding mirror 182a, and the TIR prism 170a is omitted, and the optical axis is shown in a straight line. Similarly, in (b) of FIG. 7 , the change of the optical path direction by the optical path changing mirror 181, the turning mirror 182b, and the TIR prism 170b is omitted, and the optical axis is shown in a straight line.

In addition, Fig. 6 typically shows the arrangement of each optical device when the reflective light modulation device 200b is viewed from the rear side. In addition, in FIG. 6 , illustration of a part of the illumination optical system is omitted. The illumination light directed toward the TIR prism 170b from the reflection point P of the folding mirror 182b enters the reflective light modulation device 200b at an incident angle of 45°. In addition, as the DMD device used as the reflective light modulation device 200b (and the reflective light modulation device 200a), as has been described with reference to FIG. The frame is tilted at 45°, and the reflective surface is driven according to the image signal to change the reflection direction of the illumination light.

As shown in (a) of FIG. The distance between S and Pa is La. In addition, as shown in (b) of FIG. , let the distance between S and Pb be Lb.

As illustrated in (a) and (b) of FIG. 7 , in the present embodiment, the turning mirror 182 a for the first illumination light and the turning mirror 182 b for the second illumination light are represented by La It is not necessarily equal to Lb, that is, La/Lb is not necessarily configured as 1.

For both the first illumination light and the second illumination light, since the optical path lengths from the turning mirror 182a (turning mirror 182b) to the reflective light modulation device 200a (reflective light modulation device 200b) are set to be equal, Therefore, the optical path length of the first illumination light from the light channel 140 to the reflective light modulation device 200a and the optical path length of the second illumination light from the light channel 140 to the reflective light modulation device 200b produce a difference of La-Lb=ΔL. In addition, as a structure where La/Lb is not 1, in addition to the structure of La>Lb shown in FIG. 7(a) and FIG. A return mirror 182a for the illumination light and a return mirror 182b for the second illumination light.

In this embodiment, in order to make the conditions for illuminating the reflective light modulation device 200a with the first illumination light as consistent as possible with the conditions for illuminating the reflective light modulation device 200b with the second illumination light, in the optical path of the first illumination light The intermediate image side condenser lens 160 is arranged between the dichroic mirror 180 and the turning mirror 182a, and the intermediate image side condenser lens 160 is arranged between the dichroic mirror 180 and the optical path changing mirror 181 in the optical path of the second illumination light. The lens 161 and the relay lens 162 are disposed between the optical path changing mirror 181 and the folding mirror 182b. By appropriately setting the positions and focal lengths of these lenses, it is possible to reduce the influence of the difference in optical path length ΔL and make the illumination conditions of the two reflective light modulation devices consistent.

In addition, in this embodiment, as described above, the fluorescent light having the spectral characteristics shown in FIG. Preferably, a cyan filter CF is provided in the first illumination optical system, and a red filter RF is provided in the second illumination optical system. Although the positions where the filters are set are arbitrary, in this embodiment, considering the symmetry of the optical systems, dichroic filters ( multilayer film filter). That is, as shown in (a) of Figure 7, the cyan color filter CF having the characteristic shown in (a) of Figure 9 is set on the exit surface of the modulation device side condenser lens 163 of the first illumination optical system, as shown in Figure 9 As shown in (b) of FIG. 7, a red filter RF having the characteristics shown in (b) of FIG.

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

In addition, when the optical path length from the dichroic mirror 180 to the reflective light modulation device 200a is LDA, and the optical path length from the dichroic mirror 180 to the reflective light modulation device 200b is LDB, it is preferable to satisfy the following condition:

0.9<LDA/LDB<1.1...(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 the illumination light in synchronization with the color switching timing of the illumination light IL irradiated from the light source device 110.

18(a) to 18(e) are timing charts with time t on the horizontal axis for explaining the driving timing of the light source device 110 and each reflective light modulation device. As described with reference to FIG. 8( a ), FIG. 16 , and FIG. 17 , light source device 110 rotates rotating body 122 to alternately output yellow fluorescent light emitted by yellow phosphor 123Y and blue light reflected by reflector 124 . When the rotator 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 characteristic shown in FIG. 5 , the first illumination light reflected by the dichroic mirror 180 becomes a mode of alternate irradiation of G light and B light as shown in (b) of FIG. 18 . The second illumination light transmitted through the chromatic mirror 180 is intermittently irradiated with R light as shown in (d) of FIG. 18 .

When the G component and the B component of the image signal are input in synchronization with the color switching timing of the first illumination light, the image light G+B shown in (c) of FIG. 18 is output from the reflective light modulation device 200a. In addition, when the R component of the image signal is input in synchronization with the timing of turning on the R light of the second illumination light, the image light R shown in (e) of Fig. 18 is output from the reflective light modulation device 200b. The image light of each color is pulse-width-modulated by the reflective light modulation device according to the brightness of each color component in the image signal. When it is necessary to vary the pulse width (time length) corresponding to one step for each color, the clock frequency for driving the reflective light modulation device can be adjusted according to the color of the image light.

Next, a projection optical system for combining and projecting images output from the reflective light modulation device 200a and the reflective light modulation device 200b will be described.

Fig. 3 is a diagram extracting a part of the projection optical system 610 from the overall configuration of the projection display device 1 shown in Fig. 1 for the purpose of explaining the projection optical system.

As mentioned above, the reflective light modulation device 200a drives the micromirror device according to the signal component of G color or B color in the image signal, so that the first illumination light is reflected at a predetermined angle, and the output signal shown in (c) of FIG. Image light G+B. The image light G+B is transmitted from the TIR prism 170a and is incident on the first rear group lens 601a, and then is transmitted from the synthesizing prism 400 and is incident on the front group lens 602, and is magnified and projected onto the projection surface 700 (such as a projection screen).

In addition, the reflective light modulation device 200b drives the micromirror device according to 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 from the TIR prism 170b and is incident on the second rear group lens 601b, and then undergoes internal reflection in the synthesis prism 400 to change the optical path and enter the front group lens 602, and is enlarged and projected onto the projection surface 700 (such as a projection screen). )superior. In addition, in FIGS. 1 to 3 , the optical axis LX of the front group lens 602 is indicated by a dashed-dotted line.

The combination of the front group lens 602 and the first rear group lens 601a functions as a projection lens for the image light G+B. Likewise, the front group lens 602 and the second rear group lens 601b together function as a projection lens for the image light R. Here, the TIR prism 170a and the TIR prism 170b use devices with the same structure, and the first rear group lens 601a and the second rear group lens 601b use lenses with the same structure. In addition, as will be described later, in the synthesizing prism 400, 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. Therefore, in the projection lens system according to the present embodiment, image adjustment (for example, focus adjustment) on the projection plane 700 can be easily performed only by operating the front group lens 602 .

The synthesis prism 400 changes the optical path of the image light R to overlap with 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 (a) of FIG. 4 , the synthesis prism 400 is composed of three prisms: a prism 401 , a prism 402 , and a prism 403 . The prism 401 and the prism 402 face each other with an air gap AG1 as a small gap, and the prism 402 and the prism 403 face each other with an air gap AG2 as a small gap. Among the optical surfaces of the prism 402, a dielectric multilayer film 405 is provided on a surface facing the prism 401 across the air gap AG1.

After the image light R enters the prism 402 , it is totally internally reflected toward the dielectric multilayer film 405 on the optical surface on the side of the air gap AG2 . In this embodiment, the incident angle ω of the image light R with respect to the dielectric multilayer film 405 is set to ω=12 degrees. The dielectric multilayer film 405 is a film having the transmission/reflection characteristics shown in (b) of Fig. 4, and almost all of the image light R is reflected. In addition, the dielectric multilayer film 405 is not sandwiched between the prism 401 and the prism 402 without a gap (adhesion), but is separated from the prism 401 by an air gap. Therefore, compared with the bonded cross prism, The offset of PS separation width and angle offset is small, and the rising edge of the curve in the graph is steep, almost in the shape of a ladder. 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 through 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 in (b) of FIG. 4 described above, the image light G+B is transmitted through the dielectric multilayer film 405 . The image light G+B is further transmitted through the prism 402, the air gap AG2 and the prism 403 and is incident on the front group lens 602.

In addition, the incident angles with respect to the dielectric multilayer film 405 are arranged so that the image light R and the image light G+B are substantially equal, excluding manufacturing errors. In addition, the shapes of the prism 402 and the prism 401 are set such that the optical path length of the image light R after it enters the prism 402 until it reaches the dielectric multilayer film 405 is the same as the length of the image light G+B after it enters the prism 401 until it exits. The optical path lengths are equal.

According to the present embodiment described above, for example, compared with the two-panel display device disclosed in Patent Document 1, the back focus of the projection lens can be reduced, so that the device can be miniaturized. Furthermore, since a reflective light modulation device in which 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 it is an optical system that does not use a cross dichroic prism whose polarization characteristics vary greatly depending on the incident angle, it is possible to display high-quality images with uniform color shades. . That is, according to the present embodiment, it is possible to realize a highly versatile two-panel type projection display device that achieves a good balance between high image quality, miniaturization, and low cost.

[Embodiment 2]

Next, a projection display device according to Embodiment 2 will be described. However, descriptions of the same or similar parts as those in Embodiment 1 are simplified or omitted.

FIG. 10 is a typical diagram showing an optical configuration of a projection display device according to Embodiment 2. FIG. The projection display device 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). Also in this embodiment, as in Embodiment 1, a DMD having micromirror devices arranged in an array is used as the reflective light modulation device 200a and the reflective light modulation device 200b. In addition, as described with reference to FIG. 15 , as the DMD, when the screen is viewed from above, the reflective surface of the micromirror of each pixel is inclined by 45° with respect to the frame of the screen, and the reflective surface is driven according to the image signal to change the reflection direction of the illumination light. . The micromirror corresponding to each pixel is driven according to the brightness level of the image signal so that the reflection direction is 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.

(b) of FIG. 8 shows the structure of the light source device 110 used in this embodiment. The light source device 110 of the present embodiment does not excite the phosphor to emit light like the light source device of the first embodiment, but uses independently driven solid light sources (for example, R, G, B semiconductor lasers or LEDs) with different color lights. ) output light is synthesized to be output as illumination light IL. That is, the light source device 110 includes a solid-state light source 111R that emits red light, a solid-state light source 112B that emits blue light, a solid-state light source 113G that emits green light, and a lens 115 that condenses the light from each light-emitting source. The dichroic mirror 807 and the red-reflecting dichroic mirror 808 overlap the optical paths of the light beams of each color, and emit the illumination light IL to the light channel 140 through the condenser lens 109 . By using a solid-state light source (for example, a semiconductor laser or an LED), in the present embodiment, it is possible to emit illumination light IL with higher color purity to the light tunnel 140 than phosphors.

Fig. 11 is a diagram showing a part of the illumination optical system in Embodiment 2 extracted, and corresponds to Fig. 2 in Embodiment 1. The basic structure of the illumination optical system in this embodiment is similar to Embodiment 1, but as shown in the table in the figure, the installation angle and position of each optical device are different. In this embodiment, in order to make the conditions for illuminating the reflective light modulation device 200a with the first illuminating light as consistent as possible with the conditions for illuminating the reflective light modulating device 200b with the second illuminating light, the optical path of the first illuminating light The intermediate image side condenser lens 160 is arranged between the dichroic mirror 180 and the turning mirror 182a, and the intermediate image side condenser lens 160 is arranged between the dichroic mirror 180 and the optical path changing mirror 181 in the optical path of the second illumination light. In the optical lens 161, the relay lens 162 is arranged between the optical path changing mirror 181 and the folding mirror 182b. By appropriately setting the positions and focal lengths of these lenses, it is possible to reduce the influence of the difference in optical path length ΔL and make the illumination conditions of the two reflective light modulation devices consistent.

In addition, Fig. 14 typically shows the arrangement of each optical device when the reflective light modulation device 200b is viewed from the rear side. In addition, in FIG. 14 , illustration of a part of the illumination optical system is omitted. The illumination light directed toward the TIR prism 170b from the reflection point P of the folding mirror 182b enters the reflective light modulation device 200b at an incident angle of 45°. In addition, as the DMD device used as the reflective light modulation device 200b (and the reflective light modulation device 200a), as has been described with reference to FIG. The frame is tilted at 45°, and the reflective surface is driven according to the 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 device 110.

19(a) to 19(e) are timing charts with time t on the horizontal axis for explaining the driving timing of the light source device 110 and each reflective light modulation device. As described with reference to (b) of FIG. 8 , the light source device 110 includes 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 independent drivable solid-state light sources with different color lights. solid light source. As shown in (a) of FIG. 19 , during 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 turns on the solid light source 112B to output B light.

Since the dichroic mirror 180 has the transmission characteristics shown in FIG. 5 , the first illumination light reflected by the dichroic mirror 180 becomes a mode of alternate irradiation of G light and B light as shown in (b) of FIG. 19 . The second illumination light transmitted through the chromatic mirror 180 is intermittently irradiated with R light as shown in (d) of FIG. 19 .

When the G component and the B component of the image signal are input in synchronization with the color switching timing of the first illumination light, the image light G+B shown in (c) of FIG. 19 is output from the reflective light modulation device 200a. In addition, when the R component of the image signal is input in synchronization with the timing of turning on the R light of the second illumination light, the image light R shown in (e) of Fig. 19 is output from the reflective light modulation device 200b. The image light of each color is pulse-width-modulated by the reflective light modulation device according to the brightness of each color component in the image signal. When it is necessary to vary the pulse width (time length) corresponding to one step for each color, the clock frequency for driving the reflective light modulation device can be adjusted according to the color of the image light.

In addition, the driving timing is not limited to the examples shown in (a) to (e) of FIG. 19 , and may be, for example, those shown in (a) to (e) of FIG. 20 . As shown in (a) of FIG. 20 , the solid-state light source 111R is turned on to output R light over the entire period corresponding to one frame of the image signal, and at the same time Among them, for example, about 2/3 of solid light sources 113G that emit green light are turned on to output G light, and the remaining about 1/3 of solid light sources 112B are 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 becomes a mode of alternate irradiation of G light and B light as shown in (b) of FIG. 20 . The second illumination light transmitted through the chromatic mirror 180 is continuously irradiated with R light as shown in (d) of FIG. 20 .

When the G component and the B component of the image signal are input in synchronization with the color switching timing of the first illumination light, the image light G+B shown in (c) of FIG. 20 is output from the reflective light modulation device 200a. In addition, when the R component of the image signal is input in synchronization with the frame switching timing, the image light R shown in (e) of Fig. 20 is output from the reflective light modulation device 200b. The image light of each color is pulse-width-modulated by the reflective light modulation device according to the brightness of each color component in the image signal. When it is necessary to vary the pulse width (time length) corresponding to one step for each color, the clock frequency for driving the reflective light modulation device can be adjusted according to the color of the image light.

Next, a projection optical system for combining and projecting images output from the reflective light modulation device 200a and the reflective light modulation device 200b will be described.

Fig. 12 is a diagram extracting a portion of the projection optical system 610 from the overall configuration of the projection display device 2 shown in Fig. 10 for the purpose of explaining the projection optical system.

As mentioned above, the reflective light modulation device 200a drives the micromirror device according to the signal component of G color or B color in the image signal, so that the first illumination light is reflected at a predetermined angle, and outputs (c) of FIG. 19 or FIG. 20 Image light G+B shown in (c). The image light G+B transmits from the TIR prism 170 a and enters the first relay lens 611 a , and then transmits from the synthesizing prism 410 and passes through the third relay lens 612 to form an intermediate image 613 . The intermediate image 613 is magnified and projected onto a projection surface 700 (for example, a projection screen) through a projection lens 614 disposed on the magnification side.

In addition, the reflective light modulation device 200b drives the micromirror device according to the signal component of the R color in the image signal, so that the second illumination light is reflected at a predetermined angle, and the output is as shown in (e) of FIG. 19 or (e) of FIG. 20 . The image light R. The image light R is transmitted from the TIR prism 170b, enters the second relay lens 611b, and is internally reflected in the combining prism 410 to change the optical path, and passes through the third relay lens 612 to form an intermediate image 613. The intermediate image 613 is enlarged and projected onto the projection surface 700 (such as a projection screen) through the projection lens 614 .

Thus, this embodiment differs from Embodiment 1 in that it has a configuration in which an intermediate image of a display image is temporarily formed in front of the projection lens 614 using a relay lens. In the present embodiment, since the diameter of light in the vicinity of the stop of the relay lens can be reduced, the combining prism 410 can be miniaturized.

The synthesis prism 410 changes the optical path of the image light R to overlap with 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 (a) of FIG. 13 , the synthesis prism 410 is composed of two prisms, a prism 411 and a prism 412 . The prism 411 and the prism 412 face each other across an air gap AG3 which is a small gap. Among the optical surfaces of the prism 411, a dielectric multilayer film 415 is provided on a surface facing the prism 412 across the air gap AG3.

After the image light R enters the prism 411, it is totally internally reflected toward the dielectric multilayer film 415 on the optical surface on the third relay lens 612 side. In this embodiment, the incident angle ω of the image light R with respect to the dielectric multilayer film 415 is set to ω=26.5 degrees. The dielectric multilayer film 415 is a film having the transmission/reflection characteristics shown in (b) of FIG. 13 , and almost all of the image light R modulated by the solid-state light source with good monochromaticity is reflected. In addition, the dielectric multilayer film 415 is not sandwiched between the prism 411 and the prism 412 without a gap (adhesion), but has an air gap between the prism 412. Therefore, compared with the bonded cross prism, The offset of PS separation width and angle offset is small, and the rising edge of the curve in the graph is steep, almost step-like. The image light R reflected by the dielectric multilayer film 415 is transmitted through the prism 411 and enters the third relay lens 612 .

On the other hand, the image light G+B is transmitted through 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 in (b) of FIG. 13 described above, the image light G+B modulated by the illumination light with good monochromaticity from the solid-state light source is transmitted through the dielectric multilayer film 415 . The image light G+B is further transmitted from the prism 411 and enters the third relay lens 612.

In addition, the incident angles with respect to the dielectric multilayer film 415 are arranged to be equal between the image light R and the image light G+B. In addition, the shapes of prism 411 and prism 412 are set such that the optical path length after image light R enters prism 411 and reaches dielectric multilayer film 415 is the same as that of image light G+B after entering prism 412 until it exits. The optical path lengths are equal.

According to the present embodiment described above, for example, compared with the two-panel display device disclosed in Patent Document 1, the back focus of the projection lens can be reduced, so that the device can be miniaturized. Furthermore, since a reflective light modulation device in which 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 it is an optical system that does not use a cross dichroic prism whose polarization characteristics vary greatly depending on the incident angle, it is possible to display high-quality images with uniform color shades. . That is, according to the present embodiment, it is possible to realize a highly versatile two-panel type projection display device that achieves a good balance between high image quality, miniaturization, and low cost.

[Other implementations]

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

For example, the light source device used in Embodiment 1 and the projection optical system used in Embodiment 2 to form an intermediate image may be combined. Alternatively, the light source device used in Embodiment 2 may be combined with the projection optical system used in Embodiment 1 that does not form an intermediate image.

In Embodiment 1, the incident angles ω of the first image light (R+G) and the second image light (R) incident on the dielectric multilayer film 405 of the synthesis prism 400 are set to be substantially equal except for manufacturing errors. The size of , and set ω = 12 degrees. In addition, 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 synthesis prism 410 is set to substantially excluding manufacturing errors. equal in size and set to ω = 26.5 degrees. When implementing the present invention, the incident angle ω is not limited to 12 degrees or 26.5 degrees, and the incident angle ω is set within a range of not less than 10 degrees and not more than 27 degrees.

For example, a screen is often used together with a projection display device as a component of a projection display system, but the embodiments of the present invention are not limited thereto. As described above, the projection display device according to the embodiment is easy to operate when optically adjusting the displayed image, so it is also suitable for portable use, for example, it can be easily placed on any surface of any place such as the wall of a building without a screen. The display image is projected on.

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