JP2008134276A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector easily achieving the prolongation of the lives of parts installed in the optical path of blue light without making the color temperature of white light fall. <P>SOLUTION: In the projector 10, when separating the optical paths OP1, OP2 and OP3 in a color separation device 40, a part of the blue light LB is guided to another optical path OP2 for green light LG, so that the quantity of the blue light LB guided to the optical path OP1 for the blue light LB is reduced and the life of the part such as a polarizing filter 62b arranged along the path is prolonged. In such a case, the luminance of a blue image formed by liquid crystal light valves for blue 61b and 62b is low but the color temperature of the white light is kept high as a whole if the luminance of the blue component of an image formed by another liquid crystal light valves for green 61g and 62g is relatively increased. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a projector that illuminates a liquid crystal light bulb with illumination light from a lamp light source and projects modulated light that has passed through the liquid crystal light bulb.

A conventional general projector includes a light source including a lamp, an illumination optical system that uniformizes and converts the light from the light source, and a color separation optical system that separates light that has passed through the illumination optical system into three colors. Three liquid crystal panels illuminated by three colors of illumination light, a cross dichroic prism that synthesizes images from these three liquid crystal panels, and a projection lens that projects a magnified image after synthesis (see, for example, Patent Document 1) ). Here, the color separation optical system is composed of two dichroic mirrors whose cutoff wavelengths are the boundary wavelengths of blue light, green light, and red light, and each color light is separated stepwise.
JP 2004-69966 A

However, in the projector as described above, the optical path of blue light is relatively high in energy, and the component life is shorter than the optical paths of other colors. For this reason, it is conceivable that an ND filter is inserted in the optical path of blue light to extend the life of the component, but the color temperature of white decreases as the blue light is dimmed.

Therefore, an object of the present invention is to provide a projector that can easily extend the life of components installed in the optical path of blue light without lowering the white color temperature.

In order to solve the above problems, a projector according to the present invention is (a) an illumination device having a light source device that emits light source light including blue light, green light, and red light, and (b) emitted from the illumination device. A color separation optical system that separates the illumination light into a plurality of optical paths for blue light, green light, and red light, and guides part of the blue light onto the optical paths for other color lights when separating the optical paths; ) A liquid crystal light valve for each color light that modulates the light guided to the optical path for each color light separated by the color separation optical system according to image information; and (d) each color modulated by the liquid crystal light valve. A light combining optical system that combines the image light; and (e) a projection optical system that projects the image light that has passed through the light combining optical system.

In the projector, the color separation optical system guides part of the blue light onto the optical path for the other color light when the optical path is separated, so that the amount of blue light guided to the optical path for blue light is reduced, and the path It is possible to extend the life of the parts arranged along. At this time, the luminance of the blue image formed by the liquid crystal light valve for blue light is reduced, but the luminance of the blue component of the image formed by the liquid crystal light valve for other color light is relatively increased. As a white color temperature can be maintained.

Further, according to a specific aspect or aspect of the present invention, in the projector, the liquid crystal light valve for each color light is a region on the chromaticity diagram corresponding to three colors of light guided to the light path for each color light. It is driven to reproduce. In this case, it becomes possible to drive to cancel the influence of the decrease in the amount of illumination light on the liquid crystal light valve for blue light and the amount of color change on the liquid crystal light valve for other color lights, and an image with good color reproducibility can be obtained. Can project.

According to another aspect of the present invention, the proportion of part of the blue light that is directed onto the light path for the other color light is determined by the lifetime of the liquid crystal light valve for blue light and the liquid crystal light valve for green light and red light. It is set so that at least one of the lifetimes is balanced. In this case, it is possible to effectively extend the life of the entire liquid crystal light valve for each color while suppressing a decrease in the amount of blue light guided to the optical path for blue light.

According to still another aspect of the present invention, the color separation optical system includes a filter that separates an optical path for blue light and an optical path for other color light, and the filter is included in each of the blue light. The wavelength component is guided to an optical path for another color light with a predetermined leakage rate. In this case, blue light can be weakened over the entire wavelength range by adjusting the transmittance and the reflectance.

According to still another aspect of the present invention, the color separation optical system includes a filter that separates an optical path for blue light and an optical path for other color light, and the filter includes a green side of blue light. The component having a predetermined wavelength width is guided to an optical path for other color light. In this case, blue light can be weakened in the boundary wavelength region by adjusting the cutoff wavelength of the filter.

According to still another aspect of the present invention, the color separation optical system includes a first dichroic filter that branches the optical path for blue light from the optical path for green light and red light, and the optical path for green light for red light. A second dichroic filter branched from the optical path, and the first and second dichroic filters guide part of the blue light onto the optical path for green light. In this case, the second dichroic filter is a conventional type, and the target color separation can be performed by changing the specifications of only the first dichroic filter.

According to still another aspect of the present invention, the color separation optical system includes a first dichroic filter that branches the optical path for red light from the optical path for green light and blue light, and the optical path for green light for blue light. A second dichroic filter branched from the optical path, the first dichroic filter,
Part of the blue light is guided onto the optical path for red light. In this case, the second dichroic filter is a conventional type, and the target color separation can be performed by changing the specifications of only the first dichroic filter.

[First Embodiment]
FIG. 1 is a conceptual diagram illustrating the configuration of the optical system of the projector according to the first embodiment of the invention.

The projector 10 is an optical device for modulating a light beam emitted from a light source according to image information to form a color optical image and enlarging and projecting the optical image on a screen. The illumination optical system 30, the color separation device 40, the light modulator 60, the cross dichroic prism 70, and the projection optical system 80 are configured. Here, the light source lamp unit 20 and the illumination optical system 30 constitute an illumination device that generates illumination light to be supplied to the color separation device 40 and the like.

The light source lamp unit 20 is a light source device that collects and emits light beams emitted from the light source lamp 21 to the surroundings and illuminates the light modulation unit 60 via the illumination optical system 30 and the like, and is a light source lamp that is a light emitting tube. 21, a concave mirror 22 that is a concave ellipse that reflects the light source light emitted from the light source lamp 21, and a concave lens 23 that collimates the light source light reflected by the concave mirror 22.
In the light source lamp unit 20, the substantially white light source light emitted from the light source lamp 21 is collimated through the concave mirror 22 and the concave lens 23, and emitted to the front side, that is, the illumination optical system 30 side. The above-described light source lamp 21 is usually a high-pressure mercury lamp because it can emit high-intensity light over various wavelengths. However, a lamp that can be incorporated in the light source lamp unit 20 is a high-pressure lamp. Not limited to mercury lamps. Further, various concave mirrors such as a paraboloid can be used in place of the elliptical concave mirror 22 described above. When a parabolic concave mirror is used, a parallel light beam can be emitted from the light source lamp unit 20 without providing the concave lens 23 or the like after the concave mirror 22.

The illumination optical system 30 equalizes the illuminance by dividing the light beam emitted from the light source lamp unit 20 into a plurality of partial light beams and superimposing them on the target illumination area, and making it incident.
An optical system that converts illumination light into polarized light in a specific direction, and includes a first lens array 31, a second lens array 32, a polarization conversion device 34, and a superimposing lens 35.

The first lens array 31 has a function as a light beam splitting optical element that splits a light beam emitted from the light source lamp 21 into a plurality of partial light beams, and is arranged in a matrix in a plane orthogonal to the system optical axis OA. A plurality of small lenses are provided. The contour shape of each small lens is set so as to be substantially similar to the shape of the image forming area of the liquid crystal display panels 61b, 61g, 61r constituting the light modulation unit 60 described later. The second lens array 32 is an optical element that collects a plurality of partial light beams divided by the first lens array 31 described above, and in the same manner as the first lens array 31, a matrix is formed in a plane orthogonal to the system optical axis OA. The plurality of small lenses are arranged in a shape, but for the purpose of condensing, the contour shape of each small lens accurately corresponds to the shape of the image forming area of the liquid crystal display panels 61b, 61g, 61r. There is no need to be.

The polarization conversion device 34 is formed of a PBS array and a phase difference plate, and has a role of aligning the polarization direction of each partial light beam divided by the first lens array 31 with one direction of linearly polarized light.
Although detailed illustration of the PBS array of the polarization converter 34 is omitted, the system optical axis O
A configuration in which polarization separation films and reflection mirrors that are inclined with respect to A are alternately arranged.
The former polarization separation film transmits one polarized light beam among the P-polarized light beam and S-polarized light beam included in each partial light beam, and reflects the other polarized light beam. The reflected other polarized light beam is bent by the latter reflecting mirror, and is emitted in the emission direction of the one polarized light beam, that is, the direction along the system optical axis OA. One of the emitted polarized light beams is polarized and converted by a phase difference plate provided in a stripe shape on the light beam emission surface of the polarization conversion device 34, and the polarization directions of all the polarized light beams are aligned. By using such a polarization conversion device 34, it is possible to align the light beam emitted from the light source lamp 21 with a polarized light beam in one direction, so that the utilization factor of the light source light used in the light modulation unit 60 is improved. Can do.

The superimposing lens 35 condenses a plurality of partial light beams that have passed through the first lens array 31, the second lens array 32, and the polarization conversion device 34, and superimposes them on the image forming regions of the liquid crystal display panels 61b, 61g, 61r. Is an optical element. The light beam emitted from the superimposing lens 35 is emitted to the color separation device 40 at the next stage while being made uniform. In other words, the illumination light that has passed through both the lens arrays 31 and 32 and the superimposing lens 35 passes through the color separation device 40 described in detail below, and then the illumination region of the light modulation unit 60, that is, the liquid crystal display panels 61b, 61g, and 61r for each color. Uniformly illuminate the image forming area.

The color separation device 40 includes first and second dichroic mirrors 41 a and 41 b and a reflection mirror 4.
2a, 42b, 42c, field lenses 43b, 43g, 43r, and relay lens 4
5 and 46. Among these, the first and second dichroic mirrors 41a and 41b constitute a color separation optical system for separating substantially white illumination light into three primary colors. Each dichroic mirror 41a, 41b is an optical element obtained by forming on a transparent substrate a dielectric multilayer film having a wavelength selection function of reflecting a light beam in a predetermined wavelength region and transmitting a light beam in another wavelength region. Yes, they are arranged in an inclined state with respect to the system optical axis OA. The first dichroic mirror 41a basically reflects the blue light LB among the three colors of blue, green, and red (B, G, and R), and transmits the green light LG and the red light LR. The second dichroic mirror 41b
Of the incident green light LG and red light LR reflects the green light LG and transmits the red light LR. As a result, the illumination light incident on the color separation device 40 from the light source lamp unit 20 via the illumination optical system 30 is reflected by the first dichroic mirror 41a and guided to the first optical path OP1, and the first dichroic. The second dichroic mirror 4 is transmitted through the mirror 41a.
The green light LG reflected by 1b and guided to the second optical path OP2 is separated from the red light LR transmitted through the first and second dichroic mirrors 41a and 41b and guided to the third optical path OP3.
However, the first dichroic mirror 41a does not completely reflect the blue light LB,
A part of the blue light LB is transmitted along with the green light LG and the like. As described above, when a part of the blue light LB is transmitted by adjusting the transmission / reflection characteristics of the first dichroic mirror 41a, it is assumed that the second dichroic mirror 41b has normal transmission / reflection characteristics. A part of the light LB is intentionally guided to the second optical path OP2 for green.

Field lenses 43b, 43g, 43 for each color provided on the emission side of the color separation device 40
r is provided such that each partial light beam emitted from the second lens array 32 and incident on the light modulation unit 60 has an appropriate degree of convergence. The pair of relay lenses 45 and 46 are disposed on the third optical path OP3 for red which is relatively longer than the first optical path OP1 for blue and the second optical path OP2 for green. The relay lenses 45 and 46 transmit the image formed immediately before the incident-side first relay lens 45 to the field lens 43r on the emission side as it is, so that light use efficiency due to light diffusion or the like is achieved. Is prevented.

FIG. 2 is a graph illustrating the characteristics of the first and second dichroic mirrors 41a and 41b. In the graph, the solid line indicates the transmittance of the first dichroic mirror 41a, and the dotted line indicates the second.
The transmittance of the dichroic mirror 41b is shown. The first dichroic mirror 41a basically reflects the blue light LB, but substantially completely transmits the green light LG and the red light LR, and the cutoff wavelength corresponding to the half value at which the transmittance is switched is, for example, about 490 nm. ing. In this case, the first dichroic mirror 41a is designed to slightly transmit the blue light LB. Specifically, the transmittance of the first dichroic mirror 41a in the wavelength range of 430 to 480 is about 10%. The second dichroic mirror 41b reflects the green light LG almost completely, but almost completely transmits the red light LR, and the cutoff wavelength corresponding to the half value at which the transmittance is switched is about 590 nm, for example. That is, the former first dichroic mirror 41a is different from a normal one, and has a leakage rate or transmittance of about 10% even in the blue wavelength region, while the latter second dichroic mirror 41b is a normal one and has a blue color. The transmittance is almost 0% in the wavelength region and the green wavelength region. As a result, in FIG. 1, about 10% of the blue light LB incident on the color separation device 40 is transmitted through the first dichroic mirror 41a, but is reflected by the second dichroic mirror 41b and enters the second optical path OP2 for green. Led.

As is clear from the above, most of the blue light LB reflected by the first dichroic mirror 41a is weakened to about 90%, but most of it is guided to the first optical path OP1, and the reflection mirror 42a.
Then, it enters the field lens 43b at the final stage. The first dichroic mirror 4
The green light LG transmitted through 1a and reflected by the second dichroic mirror 41b and the weak blue light LB of about 10% are guided to the second optical path OP2 and enter the field lens 43g at the final stage. Further, the red light LR that has passed through the second dichroic mirror 41b is transmitted through the third optical path OP.
3, and enters the final stage field lens 43 r through the reflection mirrors 42 b and 42 c and the relay lenses 45 and 46.

The light modulation unit 60 includes three liquid crystal display panels 61b, 61g, and 61r on which illumination lights LB, LG, and LR of three colors are incident, respectively. Here, the liquid crystal display panel 61b for blue light LB and the pair of polarization filters 62b and 62b sandwiching the liquid crystal display panel 61b constitute a liquid crystal light valve for two-dimensionally modulating the luminance of illumination light based on image information. . The liquid crystal display panel 61g for green light LG and the pair of polarizing filters 62g and 62g sandwiching the liquid crystal display panel 61g also constitute a green liquid crystal light valve, and similarly, a pair of liquid crystal display panel 61r for red light LR and a pair. The polarizing filters 62r and 62r also constitute a red liquid crystal light valve. Each liquid crystal display panel 61b, 6
1g and 61r are liquid crystal which is an electro-optical material hermetically sealed between a pair of transparent glass substrates. For example, a polarized light beam incident on each of them according to a given image signal using a polysilicon TFT as a switching element. Modulate the polarization direction.

In this light modulation unit 60, the blue light LB guided to the first optical path OP1 and weakened to about 90% is incident on the illumination region provided at the position of the liquid crystal display panel 61b via the field lens 43b. The image forming area in the panel 61b is illuminated. The green light LG guided to the second optical path OP2 and the original weak blue light LB of about 10% are incident on the illumination area provided at the position of the liquid crystal display panel 61g via the field lens 43g, and the liquid crystal display panel 61g. The image forming area inside is illuminated. The red light LR guided to the third optical path OP3 enters the illumination area provided at the position of the liquid crystal display panel 61r via the first and second relay lenses 45 and 46 and the field lens 43r, and enters the liquid crystal display panel 61r. Illuminate the image forming area. Each of the liquid crystal display panels 61b, 61g, and 61r is a non-light-emitting and transmissive light modulation device for changing the spatial distribution of the polarization direction of incident illumination light. The light beams LB, LG, and LR incident on the liquid crystal display panels 61b, 61g, and 61r are in units of pixels in accordance with drive signals or control signals input as electrical signals to the liquid crystal display panels 61b, 61g, and 61r. Is used to adjust the polarization state. At that time, each of the liquid crystal display panels 6 is provided by the polarizing filters 62b, 62g, and 62r.
The polarization direction of the illumination light incident on 1g, 61r is adjusted, and the polarization filter 62b,
The modulated light having a predetermined polarization direction is extracted from the light emitted from the liquid crystal display panels 61b, 61g, 61r by 62g, 62r.

Here, since the blue light LB weakened to about 90% is incident on the liquid crystal light valves 61b and 62b for blue, the field lens 43b disposed in the first optical path OP1,
The intensity of exposure of the optical elements such as the polarizing filter 62b and the liquid crystal display panel 61b to the blue light LB can be reduced, and the lifetime of these optical elements can be increased as compared with a normal case. As a result of the above, the weak blue light LB of about 10% is originally incident on the green liquid crystal display panel 61g, but if this is the case, the field lens 43g disposed in the second optical path OP2 Damage to optical elements such as the polarizing filter 62g and the liquid crystal display panel 61g does not increase so much.

The cross dichroic prism 70 is a light combining optical system that forms a color image by combining optical images modulated for the respective color lights emitted from the polarization filters 62b, 62g, and 62r. The cross dichroic prism 70 has a substantially square shape in plan view in which four right angle prisms are bonded together, and a pair of dielectric multilayer films 71 and 72 intersecting in an X shape are formed at the interface where the right angle prisms are bonded to each other. Is formed. One first dielectric multilayer film 71 reflects blue light, and the other second dielectric multilayer film 72 reflects red light. The cross dichroic prism 70 reflects the blue light LB from the liquid crystal display panel 61b by the first dielectric multilayer film 71 and emits the green light LG from the liquid crystal display panel 61g to the first and second sides. The red light LR from the liquid crystal display panel 61r is secondly emitted and emitted straight through the dielectric multilayer films 71 and 72.
The light is reflected by the dielectric multilayer film 72 and emitted to the left in the traveling direction. The first dielectric multilayer film 71 provided on the cross dichroic prism 70 is the first dichroic mirror 41a.
Similarly, the blue light LB can be designed to be slightly transmitted. In this case, a blue image from the liquid crystal display panel 61g can be appropriately transmitted.

The image light combined by the cross dichroic prism 70 in this way is projected as a color image on a screen (not shown) at an appropriate magnification through a projection optical system 80 as a magnification projection lens.

FIG. 3 is a block diagram conceptually illustrating a circuit portion 90 for controlling the projector 10 of FIG. The circuit portion 90 includes an image processing unit 92 that performs necessary image processing on a signal such as a video signal input from the outside, and the liquid crystal display panels 61b, 61g, and 61r based on the output of the image processing unit 92. A panel driving unit 93 for driving and a main control unit 97 for comprehensively controlling these operations are provided.

Among the circuit portions 90 described above, the image processing unit 92 is a unit for converting a video signal into a signal suitable for the operation of the panel driving unit 93, and an image correction circuit that appropriately performs correction processing on the input image signal. 92a. The image processing unit 92, that is, the image correction circuit 92 a performs various image processing such as gradation correction, color correction, and distortion correction on the video signal based on a command from the main control unit 97.

The panel drive unit 93 generates a drive signal for adjusting the display state of each of the liquid crystal display panels 61b, 61g, 61r based on the image signal after image processing output from the image processing unit 92. Thereby, in response to the image signal output from the image processing unit 92, the liquid crystal display panel 61b,
An image (moving image or still image) as a transmittance distribution can be formed in each color liquid crystal light valve composed of 61g, 61r and the accompanying polarizing filters 62b, 62g, 62r.

The main control unit 97 controls the overall operation of the projector 10 as a control device. The main control unit 97 is composed of a microcomputer or the like and incorporates a storage unit 97a for holding various data necessary for the operation of the projector 10. . The storage unit 97a stores various programs for operating the projector 10, and appropriately maintains the operating state of the projector 10. At this time, as described with reference to FIG. 1 and the like, the blue light LB is weakened by about 90% and guided to the first optical path OP1 for blue, and the weak blue light LB of about 10% is second light path for green. OP2
Therefore, the main control unit 97 causes the image correction circuit 92a of the image processing unit 92 to perform color correction that cancels the change in the color of the illumination light. Specifically, the optical path OP1 for each color
, OP2, OP3 to reproduce the region on the chromaticity diagram corresponding to the three colors of the weakened blue light LB, the green light LG mixed with the weak blue light LB, and the red light LR. The liquid crystal display panels 61b, 61g, 61r for each color are driven. In this case, the blue liquid crystal display panel 61b is used.
It is possible to drive so as to offset the influence of the decrease in the amount of illumination light with respect to the color change amount on the green liquid crystal display panel 61g, and an image with good color reproducibility can be projected.

According to the projector 10 of the present embodiment described above, the optical path OP1 in the color separation device 40.
, OP2 and OP3, a part of the blue light LB is guided onto the other optical path OP2 for the green light LG, so that the amount of the blue light LB guided to the optical path OP1 for the blue light LB is reduced, and the path It is possible to extend the life of components such as the polarizing filter 62b disposed along the line. At this time, the luminance of the blue image formed by the liquid crystal light valves 61b and 62b for blue is reduced, but the luminance of the blue component of the image formed by the other liquid crystal light valves 61g and 62g for green is relatively low. If it is increased, the white color temperature as a whole can be kept high.

Hereinafter, modifications of the projector 10 according to the first embodiment will be described. The projector of this modification has the same structure as the projector 10 shown in FIG. FIG. 4 shows first and second dichroic mirrors 41a incorporated in the projector 10 according to the modification.
It is a graph explaining the characteristic of 41b. In the graph, the solid line is the first dichroic mirror 4
The transmittance of 1a is shown, and the dotted line shows the transmittance of the second dichroic mirror 41b.

In this case, the first dichroic mirror 41a basically reflects the blue light LB, but substantially transmits part of the green-side blue light LB and all of the green light LG and red light LR, and the transmittance thereof. The cut-off wavelength corresponding to the half value at which is switched is, for example, about 480 nm. That means
The first dichroic mirror 41a transmits an extra component having a wavelength width of about 10 nm at the green side end of the blue light LB as compared with the conventional type. The second dichroic mirror 41b is the same as that shown in FIG. As a result, the long wavelength component on the green side of the blue light LB incident on the color separation device 40 is transmitted through the first dichroic mirror 41a.
The light is reflected by the second dichroic mirror 41b and guided to the second optical path OP2 for green.

In summary, the blue light LB reflected by the first dichroic mirror 41a is weakened by the cut on the long wavelength side, guided to the first optical path OP1, and incident on the final stage field lens 43b via the reflection mirror 42a. . Further, the green light LG transmitted through the first dichroic mirror 41a and reflected by the second dichroic mirror 41b and the weak blue light LB only on the long wavelength side are guided to the second optical path OP2 and the final stage field lens 43g. Is incident on. Further, the red light LR that has passed through the second dichroic mirror 41b is guided to the third optical path OP3, and enters the final stage field lens 43r via the reflection mirrors 42b and 42c and the relay lenses 45 and 46.

In the above, the first dielectric multilayer film 71 provided in the cross dichroic prism 70 can transmit the component on the long wavelength side of the blue light LB, similarly to the first dichroic mirror 41a. .

Also in this modified example, since a part of the blue light LB is guided onto the other optical path OP2 for the green light LG, the amount of the blue light LB guided to the optical path OP1 for the blue light LB is reduced and along the path. The lifetime of parts such as the polarizing filter 62b disposed in the vicinity can be extended. At this time, the supply amount of the blue light LB to the green liquid crystal light valves 61g and 62g is increased by the decrease in the supply amount of the blue light LB to the blue liquid crystal light valves 61b and 62b, and therefore the cross dichroic prism. In 70, the white color temperature can be kept high for the combined projection image.

[Second Embodiment]
Hereinafter, a projector according to a second embodiment of the invention will be described. Note that the projector according to the second embodiment is obtained by partially changing the projector according to the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

FIG. 5 is a conceptual diagram illustrating the configuration of the optical system of the projector according to the second embodiment. In this case, the color separation device 140 includes the first and second dichroic mirrors 141a and 141b,
Reflecting mirrors 42a, 42b, 42c, field lenses 43b, 43g, 43r, and relay lenses 45, 46 are provided. Among these, the first dichroic mirror 141a constituting the color separation optical system basically reflects the red light LR and guides it to the first optical path OP1 for red, and the second dichroic mirror 141b transmits the green light LG. By reflecting the light, the light is guided to the second optical path OP2 for green, and the third light path O3 for blue is transmitted by transmitting the blue light LB.
Lead to P3. However, the first dichroic mirror 141a does not transmit 100% of the blue light LB, but reflects part of the blue light LB together with the red light LR and the like. In this way, the blue light LB is adjusted by adjusting the transmission / reflection characteristics of the first dichroic mirror 141a.
When a part of the light is reflected, a part of the blue light LB is intentionally guided to the third optical path OP3 for red.

FIG. 6 is a graph illustrating the characteristics of the first and second dichroic mirrors 141a and 141b. In the graph, the solid line indicates the transmittance of the first dichroic mirror 141a, and the dotted line indicates the transmittance of the second dichroic mirror 141b. First dichroic mirror 141
a reflects the red light LR almost completely and transmits the green light LG almost completely, but the blue light LB reflects about 10% and transmits about 90% thereof. That is, the first dichroic mirror 141a has a reflectance of about 10% even in the blue wavelength region, unlike the normal one, whereas the second dichroic mirror 41b is a normal one. As a result, about 90% of the blue light LB incident on the color separation device 40 is transmitted through the first dichroic mirror 141a and finally led to the third optical path OP3 for blue, but about 10% of the blue light LB. Are reflected by the first dichroic mirror 141a and guided to the first optical path OP1 for red.

According to the projector 10 of the present embodiment described above, the optical path OP1 in the color separation device 40.
, OP2 and OP3, a part of the blue light LB is guided onto another optical path OP1 for the red light LR, so that the amount of the blue light LB guided to the optical path OP3 for the blue light LB is reduced, and the path It is possible to extend the life of components such as the polarizing filter 62b disposed along the line. At this time, the luminance of the blue image formed by the liquid crystal light valves 61b and 62b for blue is reduced, but the luminance of the blue component of the image formed by the other liquid crystal light valves 61g and 62g for green is relatively low. If it is increased, the white color temperature as a whole can be kept high.

Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

That is, in the above embodiment, the case where a part of the blue light LB is guided to the first optical path OP1 and the third optical path OP3 is described, but the blue light LB can also be guided to the second optical path OP2. In this case, a part of the blue light LB is distributed to the first optical path OP1 and the third optical path OP3.

In the above embodiment, about 10% of the blue light LB is used for the first optical path OP1 and the third optical path OP3.
However, the ratio of guiding the blue light LB to the other optical path is not limited to 10% and can be changed as appropriate. At this time, by setting the lifetimes of the liquid crystal light valves 61b and 62b for blue light and the lifetimes of the liquid crystal light valves 61g and 62g for green light to be substantially the same,
The lifetime of the projector 10 as a whole can be effectively extended.

In the projector 10 of the above embodiment, the light source lamp 2 of the light source lamp unit 20 is also used.
Although a high-pressure mercury lamp is used as 1, various lamps capable of obtaining substantially white illumination light can be used.

In the projector 10 of the above embodiment, the illumination optical system 30 is replaced with the lens arrays 31 and 3.
2, the polarization conversion device 34 and the superimposing lens 35 are provided. However, the lens arrays 31, 32 and the like can be omitted, or can be replaced with a rod integrator.

In this embodiment, an example in which the present invention is applied to a transmissive projector has been described. However, the present invention can also be applied to a reflective projector. Here, “transmission type” means that a light valve including a liquid crystal display panel or the like is a type that transmits light, and “reflection type” is a type that the light valve reflects light. It means that.

Further, the present invention can be applied to a front projection type projector that projects from the side that observes the projected image, and a rear projection type projector that projects from the side opposite to the side that observes the projected image.

It is a top view for demonstrating the optical system of the projector which concerns on 1st Embodiment. 2 is a graph showing characteristics of a dichroic filter in the projector of FIG. It is a block diagram explaining the circuit part for controlling the projector of FIG. It is a graph which shows the characteristic of the dichroic filter of the projector of a modification. It is a top view for demonstrating the optical system of the projector which concerns on 2nd Embodiment. 6 is a graph showing characteristics of a dichroic filter in the projector of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Projector, 20 ... Light source lamp unit, 30 ... Illumination optical system, 31, 3
2 ... Lens array, 34 ... Polarization conversion device, 35 ... Superposition lens, 40 ... Color separation device,
41a ... 1st dichroic mirror, 41b ... 2nd dichroic mirror, 43b
, 43g, 43r ... field lens, 45, 46 ... relay lens, 45, 46 ... second relay lens, 60 ... light modulator, 61b, 61g, 61r ... liquid crystal display panel, 6
2b, 62g, 62r ... polarizing filter, 70 ... cross dichroic prism, 71
72 ... Dielectric multilayer film, 80 ... Projection optical system, 90 ... Circuit part, 92 ... Image processing unit,
93 ... Panel drive unit, 97 ... Main control unit, LB, LG, LR ... Each color light, OA ... System optical axis, OP1 ... First optical path, OP2 ... Second optical path, OP3 ... Third optical path

Claims (7)

A lighting device having a light source device that emits light source light including blue light, green light, and red light;
A color that separates the illumination light emitted from the illuminating device into a plurality of optical paths for blue light, green light, and red light, and guides a part of the blue light onto an optical path for other color light when the optical path is separated. A separation optical system;
A liquid crystal light valve for each color light that modulates the light guided to the optical path for each color light separated by the color separation optical system according to image information;
A light combining optical system that combines image light of each color modulated by the liquid crystal light valve; and a projection optical system that projects image light that has passed through the light combining optical system;
A projector comprising: 2. The projector according to claim 1, wherein the liquid crystal light valve for each color light is driven so as to reproduce a region on a chromaticity diagram corresponding to three colors of light guided to an optical path for each color light. The ratio of part of the blue light to the optical path for the other color light balances the life of the liquid crystal light valve for blue light and the life of at least one of the liquid crystal light valves for green light and red light. The projector according to any one of claims 1 and 2, wherein the projector is set to. The color separation optical system includes a filter that separates an optical path for blue light and the optical path for other color light, and the filter separates each wavelength component contained in blue light with a predetermined leakage rate. The projector according to any one of claims 1 to 3, wherein the projector is guided to an optical path for another color light. The color separation optical system includes a filter that separates an optical path for blue light from the optical path for the other color light, and the filter removes a component having a predetermined wavelength width on the green side of the blue light from the other. The projector according to any one of claims 1 to 3, wherein the projector is led to an optical path for colored light. The color separation optical system includes a first dichroic filter that branches an optical path for blue light from an optical path for green light and red light, and a second dichroic filter that branches an optical path for green light from an optical path for red light. The projector according to claim 1, wherein the first and second dichroic filters guide part of blue light onto the optical path for green light. The color separation optical system includes a first dichroic filter that branches an optical path for red light from an optical path for green light and blue light, and a second dichroic filter that branches an optical path for green light from an optical path for blue light. The projector according to claim 1, wherein the first dichroic filter guides part of blue light onto an optical path for red light.

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