JP2021124651A - Projection type video display device and light source device - Google Patents

Abstract

To provide a projection type video display device and a light source device more inexpensively.SOLUTION: A light source device which generates white light based on light emitted from a blue light source comprises: the blue light source; a polarization separation mirror; a phosphor; and a diffuser plate. The blue light source emits the blue polarized light in a first polarization direction being the S polarized light or P polarized light. Regarding the spectral characteristics of the polarization separation mirror, when defining a spectroscopy ratio of spectrally separating the incident light to a reflection optical path as a reflectance ratio and defining the spectroscopy ratio of spectrally separating the incident light to a transmission optical path as a transmission ratio, for a first spectroscopy ratio being the spectroscopy ratio of one of the reflectance ratio and the transmission ratio in a dominant wavelength of the blue light source, the first spectroscopy ratio for the first polarization direction is set to be substantially 80% with respect to the first spectroscopy ratio for a second polarization direction orthogonal to the first polarization direction. In a fluorescence spectrum wavelength band having a green light band and a red band, it may be configured that the transmission ratio for the first polarization direction becomes substantially equal to the transmission ratio for the second polarization direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a projection type image display device and a light source device, for example, to a technique for generating white light.

Patent Document 1 discloses a light source device that uses a retardation plate in the process of generating white light from a blue light source.

Japanese Unexamined Patent Publication No. 2016-142983

In the technique disclosed in Patent Document 1, it is necessary to use a retardation plate in the process of generating white light from a blue light source, and the cost reduction is not sufficient.

An object of the present invention is to provide a projection type image display device and a light source device at a lower cost.

One embodiment of the present invention is, for example, a light source device that generates white light based on light emitted from a blue light source, comprising the blue light source, a polarizing separation mirror, a phosphor, and a diffuser, and said blue. The light source emits blue polarized light in the first polarization direction, which is S-polarized light or P-polarized light. The first polarization, which is either the reflectance or the transmittance at the main wavelength of the blue light source, is defined as the transmittance. The first transmittance with respect to the direction is set to approximately 80% of the first transmittance with respect to the second polarization direction orthogonal to the first polarization direction, and the fluorescence spectrum wavelength having a green light band and a red band. In the band, the transmittance in the first polarization direction and the transmittance in the second polarization direction may be substantially equal to each other.

By briefly explaining the effects obtained by the representative inventions disclosed in the present application, it becomes possible to provide a projection type image display device and a light source device at a lower cost.

It is a figure which shows the structural example of the projection type image display device by one Embodiment of this invention. It is explanatory drawing of an example of the light source apparatus by Embodiment 1 of this invention. It is explanatory drawing of an example of the light source apparatus by Embodiment 1 of this invention. It is explanatory drawing of an example of the illumination optical system by one Embodiment of this invention. It is explanatory drawing of an example of the light source apparatus by Embodiment 2 of this invention. It is explanatory drawing of an example of the light source apparatus by Embodiment 2 of this invention. It is explanatory drawing of an example of the light source apparatus by Embodiment 3 of this invention. It is explanatory drawing of an example of the light source apparatus by Embodiment 3 of this invention. It is explanatory drawing of an example of the light source apparatus according to Embodiment 4 of this invention. It is explanatory drawing of an example of the light source apparatus according to Embodiment 4 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in all the drawings for explaining the embodiment, in principle, the same members are designated by the same reference numerals, and the repeated description thereof will be omitted.

(Embodiment 1)
FIG. 1 is a configuration diagram showing an optical system 1 of a projection type image display device 100 according to the present embodiment. In FIG. 1, the optical system 1 of the projection type image display device 100 is mainly composed of a light source device 2, an illumination optical system 3, a color separation optical system 4, an image display element 6R, 6G, 6B, and a synthetic optical system. A certain photosynthetic prism 7 and a projection lens 8 which is a projection optical system are provided.

The overall operation of the optical system 1 of the projection type image display device 100 will be described with reference to FIG. The details of the light source device 2 will be described later, but from the light source device 2, blue light B (light in the blue band, hereinafter also referred to as “B light”) and fluorescence Y (hereinafter, also referred to as yellow light “Y light”). ) And the B + Y light, which is a white light W light source group (note that the white light W is also referred to as “W light” below) is obtained. Here, the fluorescence Y is yellow fluorescence including light in the green band and light in the red band. The white light W luminous flux group is divided into a plurality of lights by a plurality of lens cells of the multi-lens 31 of the illumination optical system 3, and is efficiently guided to the second multi-lens 32 and the polarization conversion element 33. Then, the light is polarized in a predetermined polarization direction by the polarization conversion element 33 (also called a polarization conversion element). The polarized light is condensed by the condenser lens 34 and incident on the color separation optical system 4.

In the color separation optical system 4, first, the dichroic mirror 41B is irradiated, and among the irradiated white light W, the blue light LB (blue band light) is reflected, and the green light LG (green band light, hereinafter “G” is used. Light ”) and red light LR (light in the red band, hereinafter also referred to as“ R light ”) are transmitted. The reflected B light is reflected by the reflection mirror 42A, passes through the condenser lens 5B, and is incident on the image display element 6B.

On the other hand, the G light and the R light transmitted through the dichroic mirror 41B are reflected by the dichroic mirror 41G and the R light is transmitted. The reflected G light passes through the condenser lens 5G and is incident on the image display element 6G.

Further, the R light transmitted through the dichroic mirror 41G is collected by the relay lens 43 and then reflected by the reflection mirror 42b. The reflected R light is collected again by the relay lens 44 and reflected by the reflection mirror 42c. The reflected R light is further condensed by the relay lens 5R and incident on the image display element 6R. Each image display element forms an image by light intensity modulation for each pixel according to an image signal (not shown) with respect to the incident light, and generates emitted light by reflection or transmission.

In the example of FIG. 1, an example of a transmissive image display element is disclosed. The B light, G light, and R light emitted from each image display element are combined as color image projection light PJL by the photosynthesis prism 7, pass through the projection lens 8, and then reach the screen 9 which is an image projection surface. That is, the optical image formed by the image display element is magnified and projected onto the image projection surface.

Next, the light source device 2 according to the present embodiment will be described in detail with reference to FIG.

FIG. 2A shows a part of the light source device 2 of FIG. 1 extracted and explained in detail again.

In FIG. 2A, the light source 21 is a blue laser (BL), and P-polarized blue light (B light), which is laser light, is emitted along the optical axis 1. In the example of this figure, the laser light of the light source 21 has a main wavelength of around 455 nm. Then, the reflection mirror 29 reflects the P-polarized light of blue light, and the polarization separation mirror 24A is irradiated with blue light. The polarization separation mirror 24A separates blue P-polarized light into 80% and 20% according to predetermined spectral characteristics (transmission characteristics and reflection characteristics).

In addition, in the explanatory diagram of each light source from FIG. 2 onward, an example of the ratio of P-polarized light and S-polarized light in each luminous flux is illustrated, but it is merely an example, and even if the difference is about ± 5%, the effect described in the present embodiment will be described. Is fully obtained. For example, in the example of the explanation of 100% P-polarized light in FIG. 2, there is no problem even if the P-polarized light is about 100% to 95%.

Further, for example, in the example of the explanation of 80% P-polarized light in FIG. 2, there is no problem even if the P-polarized light is about 80 ± 5%. Further, for example, in the example of the explanation of the P-polarized light of 20% in FIG. 2, there is no problem even if the P-polarized light is about 20 ± 5%. The idea is the same in the following description of each figure. For the sake of simplicity, the repeated description of the range of about ± 5% will be omitted in the following description, and representative values such as 100%, 80%, and 20% will be used for description.

In the example of FIG. 2A, 80% of the blue P-polarized light, which is the laser light, is reflected by the polarization separation mirror 24A, passes through the condenser lens 27A, and reaches the phosphor 28A. Fluorescence is generated by irradiating the phosphor 28A with blue laser light which is excitation light. In the example of (A) of FIG. 2, the fluorescence spectrum contains light of at least 500 nm to 620 nm. The fluorescence emitted by the phosphor 28A is emitted at a wide angle, but is condensed by the condenser lens 27A to become a fluorescent luminous flux, which is incident on the polarization separation mirror 24A again, passes through the polarization separation mirror 24A, and is incident on the illumination optical system 3. do. The detailed polarization state from the phosphor 28A through the polarization separation mirror 24A to the illumination optical system 3 will be described later.

On the other hand, in the example of FIG. 2A, 20% of the blue P polarized light, which is the laser light, is transmitted through the polarizing separation mirror 24A, passes through the condenser lens 25A, and is incident on the diffuser plate 26A. The blue P-polarized light is naturally diffusely reflected by the diffuser plate 26A to become a wide-angle light flux, which is incident on the condenser lens 25A again, and is condensed by the condenser lens 25A to become a blue light flux, which is again incident on the polarization separation mirror 24A. The polarization separation mirror 24A reflects and transmits a blue light flux incident from the diffuser plate 26A side with predetermined spectral characteristics. Of these, the reflected blue light flux is incident on the illumination optical system 3. The detailed polarization state of the light flux from the diffuser plate 26A to the light reflected by the polarization separation mirror 24A and incident on the illumination optical system 3 will be described later.

Next, using (B) and (C) of FIG. 2, the spectral characteristics (transmittance and reflectance characteristics) of the polarization separation mirror 24A in the example of FIG. 2 are shown. FIG. 2B is an example of transmittance, and FIG. 2C is an example of reflectance. In the description of the present embodiment, the concept of spectroscopicity will be used as a superordinate concept of transmittance and reflectance. The spectroscopic ratio indicates the ratio of the incident light to be split into one of the two optical paths. Specifically, in the light separation mirror, the spectral rate at which the incident light is separated into the reflected light path is defined as the reflectance, and the spectral rate at which the incident light is dispersed into the transmitted light path is defined as the transmittance.

The polarization separation mirror 24A in the example of FIG. 2 has a wavelength range related to the fluorescence spectrum of the phosphor (hereinafter, fluorescence spectrum wavelength band) in both the transmittance characteristics of FIG. 2B and the reflectance characteristics of FIG. 2C. In the range of 500 nm to 620 nm (also referred to as), the reflectance characteristic of P-polarized light and the spectral ratio characteristic of S-polarized light having a polarization direction orthogonal to the polarization direction of P-polarized light are substantially equal. Specifically, as shown in FIG. 2B, both P-polarized light and S-polarized light have an average transmittance of 95% or more, and have characteristics as close to 100% as possible.

That is, as shown in FIG. 2C, both P-polarized light and S-polarized light have an average reflectance of 5% or less and have characteristics as close to 0% as possible. That is, the polarization separation mirror 24A has a characteristic that both P-polarized light and S-polarized light transmit as much light as possible in the wavelength range of 500 nm to 620 nm.

On the other hand, regarding the spectral characteristics near 455 nm, which is the main wavelength of the blue laser light from the light source, the spectral characteristics of P-polarized light and the spectral characteristics of S-polarized light have different characteristics. Specifically, as shown in FIG. 2B, the transmittance of S-polarized light near 455 nm is 5% or less, and has a characteristic as close to 0% as possible. On the other hand, the transmittance of P-polarized light near 455 nm is about 20% (for example, 20 ± 5%), and has a transmittance characteristic different from that of S-polarized light. That is, as shown in FIG. 2C, the reflectance of S-polarized light near 455 nm is 95% or more, and has a characteristic as close to 100% as possible. On the other hand, the reflectance of P-polarized light near 455 nm is about 80% (for example, 80 ± 5%), and has a reflectance characteristic different from that of S-polarized light.

As described above, the polarization separation mirror 24A used in the example of FIG. 2 of the present embodiment has the same spectral characteristics of P polarization and S polarization in the wavelength range related to the fluorescence spectrum of the phosphor (for example, 500 nm to 620 nm). Then, the spectral characteristics of P-polarization and the spectral characteristics of S-polarization in the vicinity of the main wavelength (near 455 nm) of the blue laser light as the light source are made different. Specifically, it has a spectral characteristic in which the reflectance of P-polarized light near 455 nm is about 80% of the reflectance of S-polarized light. In this case, about 80% may be included in the range of, for example, 80 ± 5%. Within this range, at least it functions sufficiently as a light source of the present embodiment.

The details of the polarization state of each light flux in the light source device of FIG. 2 (A) using the spectral characteristics of the polarization separation mirror 24A described above will be described with reference to FIG.

FIG. 3A shows the color and polarization state of the light beam before it is incident on the polarization separation mirror 24A, and the color and polarization of the light reflected by the polarization separation mirror 24A, where the amount of blue laser light emitted by the light source 21 is 100%. It is a figure explaining the state, the color of the light transmitted through the polarization separation mirror 24A, and the polarization state. Specifically, the color and polarization state of the light flux before it is incident on the polarization separation mirror 24A are blue light emitted by the light source 21 and are in a P-polarized state of 100%. On the other hand, the color and polarization state of the light reflected by the polarization separation mirror 24A are P-polarized blue light due to the spectral characteristics of the polarization separation mirror 24A described in FIGS. It is 80% before the polarization separation mirror 24A is incident.

Further, the color and polarization state of the light transmitted through the polarization separation mirror 24A are P-polarized blue light due to the spectral characteristics of the polarization separation mirror 24A described with reference to FIGS. 2 (B) and 2 (C), and the amount of the light is polarized light separation. It is 20% before the mirror 24A is incident. That is, in the configuration of FIG. 2A, the polarization separation mirror 24A has a function of separating P-polarized light at a ratio of 4: 1 which is blue light emitted by the light source 21 due to the above spectral characteristics.

Next, in FIG. 3B, assuming that the amount of light emitted by the phosphor 28A is 100%, the color and polarization state of the fluorescent light flux before being incident on the polarization separation mirror 24A and the fluorescence light flux transmitted through the polarization separation mirror 24A are shown. A description of the color and polarization states is given. Specifically, the color and polarization state of the fluorescence light beam before it is incident on the polarization separation mirror 24A is yellow fluorescence emitted by the phosphor 28A, and the polarization state is unpolarized, that is, the P polarization component is 50% and the S polarization component is. It is in a 50% state.

Further, the color and polarization state of the fluorescent light flux transmitted through the polarization separation mirror 24A are such that yellow fluorescence is transmitted almost as it is due to the spectral characteristics of the polarization separation mirror 24A described with reference to FIGS. 2B and 2C, and the illumination optical system 3 Proceed towards. Therefore, the polarization state of yellow fluorescence transmitted through the polarization separation mirror 24A remains unpolarized, that is, the P polarization component is 50% and the S polarization component is 50%. That is, the spectral characteristics of the polarization separation mirror 24A have a function of transmitting unpolarized yellow fluorescence emitted by the phosphor 28A in an unpolarized state in the configuration of FIG. 2A.

Next, in FIG. 3B, assuming that the amount of blue diffused light diffused by the diffuser plate 26A is 100%, the color and polarization state of the blue diffused light before it is incident on the polarization separation mirror 24A, and the polarization separation mirror. An explanation of the color and polarization state of the blue diffused light reflected from 24A and the color and polarization state of the blue diffused light transmitted through the polarization separation mirror 24A are shown. Specifically, the color and polarization state of the diffused light before it is incident on the polarization separation mirror 24A is the blue diffused light diffused by the diffuser plate 26A, and the polarization state is unpolarized, that is, the S polarization component is 50% and the P polarization component. Is in the state of 50%.

Further, the color and polarization state of the blue diffused light reflected by the polarization separation mirror 24A are determined by the spectral characteristics of the polarization separation mirror 24A described in FIGS. It is reflected almost as it is. Of the 50% of the P-polarized light component of the blue diffused light, 40% is reflected and 10% is transmitted. That is, the spectral characteristics of the polarization separation mirror 24A show that, in the configuration of FIG. 2A, 10% (a part of the P polarization component) of the amount of blue diffused light diffused by the diffuser plate 26A is the polarization separation mirror 24A. Although it cannot reach the illumination optical system 3 through transmission, the remaining 90% of the light (S polarization component 50% and P polarization component 40%) is reflected and travels toward the illumination optical system 3.

As described above, yellow fluorescence transmitted through the polarization separation mirror 24A (unpolarized light with P polarization component 50% and S polarization component 50%) and blue diffused light reflected with the polarization separation mirror 24A (S polarization component 50% and P polarization component). 40%) of the combined light becomes white light and is supplied to the illumination optical system 3.

In the light source device of FIG. 2A described above, among the light based on the blue light emitted by the blue laser light source 21, the light component that does not reach the illumination optical system 3 due to the spectral characteristics of the polarizing separation mirror 24A is , Only 10% (P polarization component) of the blue diffused light transmitted through the polarization separation mirror 24A. Since the blue diffused light is originally based on 20% of the 100% of the blue light emitted by the light source 21 that has passed through the polarization separation mirror 24A, it does not reach the illumination optical system 3 through the polarization separation mirror 24A. The "10%" blue diffused light is about 0.2 × 0.1 = 0.02 = 2% of the 100% of the blue light emitted by the light source 21. Therefore, the light utilization efficiency of the light source device (A) of FIG. 2 utilizing the spectral characteristics of the polarization separation mirror 24A is very high.

Further, since the spectral characteristics of the polarization separation mirror 24A are used, P-polarized light may remain in the optical path from the light source to the polarization separation mirror 24A, and a retardation plate as shown in FIG. 6 of Patent Document 1 is arranged. No need. Therefore, it can be configured inexpensively. Similarly, since the spectral characteristics of the polarizing separation mirror 24A are used, the diffused light from the diffuser plate may be in an unpolarized state in the optical path from the diffuser plate to the polarization separation mirror 24A. It is not necessary to arrange the retardation plate as shown in FIGS. 2 and 6. Therefore, it can be configured inexpensively. Further, the diffusion of the diffusion plate may be natural diffusion, and it is not necessary to use a special diffusion plate for maintaining the polarized state, and the diffusion plate can be constructed at low cost.

Next, with reference to FIG. 4, the advantages of the configuration of the light source device of FIG. 2 (A) will be described. As described in FIG. 3B, the blue diffused light from the light source device of FIG. 2A toward the illumination optical system 3 is 50% S-polarized light, assuming that the diffused light generated by the diffuser is 100%. And 40% P-polarized light. This means that the proportion of S-polarized light is relatively large and the proportion of P-polarized light is low.

The illumination optical system 3 is a polarization conversion in which a polarization beam splitter (PBS) and a 1/2 retardation plate are combined to convert the polarized light directed to the display element into linearly polarized light after the multi-lens 31 and the multi-lens 32. The element 33 is provided. In PBS, S-polarized light is reflected, P-polarized light is transmitted, and P-polarized light is converted to S-polarized light by the 1/2 retardation plate in the subsequent stage of PBS.

In the configuration of the light source device (A) of FIG. 2, the blue diffused light incident on the illumination optical system 3 has a relatively lower ratio of P-polarized light than S-polarized light. The heat generation in the adhesive layer of the above can be relatively reduced. As a result, deterioration of the retardation plate and the adhesive layer between the retardation plate and PBS can be relatively suppressed, and there is an advantage that the deterioration of the optical components of the projection type image display device with time can be further reduced and the life can be extended. be.

According to the light source device according to the first embodiment of the present invention described above, a light source having higher light utilization efficiency can be realized, and this can be realized at a lower cost. As a result, according to the projection type image display device according to the first embodiment of the present invention, it is possible to realize an inexpensive projection type image display device having higher light utilization efficiency.

Further, the projection type image display device according to the first embodiment of the present invention described above can extend the life of the optical component.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described.

In the projection type image display device according to the second embodiment of the present invention, the internal configuration of the light source device 2 of the projection type image display device 1 according to the first embodiment of the present invention is shown in FIGS. It is changed to the configuration of 6.

In the description of the second embodiment, the repeated description of the configuration having the same function as the function described in the first embodiment will be omitted. Therefore, in the following description, only the part different from the first embodiment will be described. The configurations and processes not mentioned in the following description of the second embodiment are the same as those of the first embodiment.

FIG. 5A describes the details of the light source device 2 according to the second embodiment.

In FIG. 5A, the light source 21 is a blue laser (BL), and S-polarized blue light (B light), which is laser light, is emitted along the optical axis 1. In the second embodiment, the blue laser light emitted by the light source 21 is S-polarized light, which is different from the first embodiment. In the example of this figure, the laser light of the light source 21 has a main wavelength of around 455 nm. Then, the S-polarized light of blue light is reflected by the reflection mirror 29, and the polarized light separation mirror 24B is irradiated with blue light. The polarization separation mirror 24B separates blue S polarized light into 80% and 20% according to predetermined spectral characteristics (transmission characteristics and reflection characteristics).

In the example of FIG. 5A, 80% of the blue S polarized light, which is the laser light, is reflected by the polarization separation mirror 24B, passes through the condenser lens 27A, and reaches the phosphor 28A. Fluorescence is generated by irradiating the phosphor 28A with blue laser light which is excitation light. In the example of (A) of FIG. 2, the fluorescence spectrum contains light of at least 500 nm to 620 nm. The fluorescence emitted by the phosphor 28A is emitted at a wide angle, but is condensed by the condenser lens 27A to become a fluorescent luminous flux, which is incident on the polarization separation mirror 24B again, passes through the polarization separation mirror 24B, and is incident on the illumination optical system 3. do. The detailed polarization state from the phosphor 28A to the light transmitted through the polarization separation mirror 24B and incident on the illumination optical system 3 will be described later.

On the other hand, in the example of FIG. 5A, 20% of the blue S polarized light, which is the laser light, is transmitted through the polarizing separation mirror 24B, passes through the condenser lens 25A, and is incident on the diffuser plate 26A. The blue S polarized light is naturally diffusely reflected by the diffuser plate 26A to become a wide-angle light flux, which is incident on the condenser lens 25A again, and is condensed by the condenser lens 25A to become a blue light flux, which is again incident on the polarization separation mirror 24B. The polarization separation mirror 24B reflects and transmits a blue light flux incident from the diffuser plate 26A side with predetermined spectral characteristics. Of these, the reflected blue light flux is incident on the illumination optical system 3. The detailed polarization state of the light flux from the diffuser plate 26A to the light reflected by the polarization separation mirror 24B and incident on the illumination optical system 3 will be described later.

Next, using (B) and (C) of FIG. 5, the spectral characteristics (transmittance and reflectance characteristics) of the polarization separation mirror 24B in the example of FIG. 5 are shown. The polarization separation mirror 24B in the example of FIG. 5 has different spectral characteristics from the polarization separation mirror 24A of the first embodiment because it corresponds to the blue S polarization from the light source. Here, (B) of FIG. 5 is an example of transmittance, and (C) of FIG. 5 is an example of reflectance.

The polarization separation mirror 24B in the example of FIG. 5 has a wavelength range related to the fluorescence spectrum of the phosphor (hereinafter, fluorescence spectrum wavelength band) in both the transmittance characteristics of FIG. 5B and the reflectance characteristics of FIG. In the range of 500 nm to 620 nm (also referred to as), the reflectance characteristic of S-polarized light and the spectral ratio characteristic of P-polarized light having a polarization direction orthogonal to the polarization direction of S-polarized light are substantially equal. Specifically, as shown in FIG. 5B, both S-polarized light and P-polarized light have an average transmittance of 95% or more, and have characteristics as close to 100% as possible. That is, as shown in FIG. 2C, both S-polarized light and P-polarized light have an average reflectance of 5% or less and have characteristics as close to 0% as possible. That is, the polarization separation mirror 24B has a characteristic that both S-polarized light and P-polarized light transmit as much light as possible in the wavelength range of 500 nm to 620 nm.

On the other hand, regarding the spectral characteristics near 455 nm, which is the main wavelength of the blue laser light from the light source, the spectral characteristics of S-polarized light and the spectral characteristics of P-polarized light have different characteristics. Specifically, as shown in FIG. 5B, the transmittance of P-polarized light near 455 nm is 5% or less, and has a characteristic as close to 0% as possible. On the other hand, the transmittance of S-polarized light near 455 nm is about 20% (for example, 20 ± 5%), and has a transmittance characteristic different from that of P-polarized light. That is, as shown in FIG. 5C, the reflectance of P-polarized light near 455 nm is 95% or more, and has a characteristic as close to 100% as possible. On the other hand, the reflectance of S-polarized light near 455 nm is about 80% (for example, 80 ± 5%), and has a reflectance characteristic different from that of P-polarized light.

As described above, the polarization separation mirror 24B used in the example of FIG. 5 of the present embodiment has the same spectral characteristics of S polarization and P polarization in the wavelength range related to the fluorescence spectrum of the phosphor (for example, 500 nm to 620 nm). Then, the spectral characteristics of S polarization and the spectral characteristics of P polarization in the vicinity of the main wavelength (near 455 nm) of the blue laser light as the light source are made different. Specifically, it has a spectral characteristic in which the reflectance of S-polarized light near 455 nm is about 80% of the reflectance of P-polarized light. In this case, about 80% may be included in the range of, for example, 80 ± 5%. Within this range, at least it functions sufficiently as a light source of the present embodiment.

The details of the polarization state of each light flux in the light source device of FIG. 5 (A) using the spectral characteristics of the polarization separation mirror 24B described above will be described with reference to FIG.

FIG. 6A shows the color and polarization state of the light beam before it is incident on the polarization separation mirror 24B, and the color and polarization of the light reflected by the polarization separation mirror 24B, assuming that the amount of blue laser light emitted by the light source 21 is 100%. It is a figure explaining the state, the color of the light transmitted through the polarization separation mirror 24B, and the polarization state. Specifically, the color and polarization state of the light beam before it is incident on the polarization separation mirror 24B is the blue light emitted by the light source 21 and is in the state of 100% S polarization. On the other hand, the color and polarization state of the light reflected by the polarization separation mirror 24B are S-polarized blue light due to the spectral characteristics of the polarization separation mirror 24B described in FIGS. It is 80% before the polarization separation mirror 24B is incident.

Further, the color and polarization state of the light transmitted through the polarization separation mirror 24B are S-polarized light of blue light due to the spectral characteristics of the polarization separation mirror 24B described in FIGS. 5 (B) and 5 (C), and the amount of the light is polarized light separation. It is 20% before the mirror 24B is incident. That is, in the configuration of FIG. 5A, the polarization separation mirror 24B has a function of separating S-polarized light at a ratio of 4: 1 which is blue light emitted by the light source 21 due to the above spectral characteristics.

Next, in FIG. 6B, assuming that the amount of light emitted by the phosphor 28A is 100%, the color and polarization state of the fluorescent light flux before being incident on the polarization separation mirror 24B and the fluorescence light flux transmitted through the polarization separation mirror 24B are shown. A description of the color and polarization states is given. Specifically, the color and polarization state of the fluorescence light beam before it is incident on the polarization separation mirror 24B is yellow fluorescence emitted by the phosphor 28A, and the polarization state is unpolarized, that is, the S polarization component is 50% and the P polarization component is. It is in a 50% state.

Further, the color and polarization state of the fluorescent light flux transmitted through the polarization separation mirror 24B are such that yellow fluorescence is transmitted almost as it is due to the spectral characteristics of the polarization separation mirror 24B described with reference to FIGS. 5 (B) and 5 (C), and the illumination optical system 3 Proceed towards. Therefore, the polarization state of the yellow fluorescence transmitted through the polarization separation mirror 24B remains unpolarized, that is, the S polarization component is 50% and the P polarization component is 50%. That is, the spectral characteristics of the polarization separation mirror 24B have a function of transmitting unpolarized yellow fluorescence emitted by the phosphor 28A in an unpolarized state in the configuration of FIG. 5A.

Next, in FIG. 6B, assuming that the amount of blue diffused light diffused by the diffuser plate 26A is 100%, the color and polarization state of the blue diffused light before it is incident on the polarization separation mirror 24B, and the polarization separation mirror. An explanation of the color and polarization state of the blue diffused light reflected from 24B and the color and polarization state of the blue diffused light transmitted through the polarization separation mirror 24B are shown. Specifically, the color and polarization state of the diffused light before it is incident on the polarization separation mirror 24B is the blue diffused light diffused by the diffuser plate 26A, and the polarization state is unpolarized, that is, the P polarization component is 50% and the S polarization component. Is in the state of 50%.

Further, the color and polarization state of the blue diffused light reflected by the polarization separation mirror 24B are determined by the spectral characteristics of the polarization separation mirror 24B described in FIGS. It is reflected almost as it is. Of the 50% of the S-polarized light component of the blue diffused light, 40% is reflected and 10% is transmitted. That is, the spectral characteristics of the polarization separation mirror 24B are such that in the configuration of FIG. 5A, 10% (a part of the S polarization component) of the amount of blue diffused light diffused by the diffuser plate 26A is the polarization separation mirror 24B. Although it cannot reach the illumination optical system 3 through transmission, the remaining 90% of the light (P polarization component 50% and S polarization component 40%) is reflected and travels toward the illumination optical system 3.

The yellow fluorescence transmitted through the polarization separation mirror 24B (unpolarized light with 50% S polarization component and 50% P polarization component) and the blue diffused light reflected by the polarization separation mirror 24B (P polarization component 50% and S polarization component) described above. 40%) of the combined light becomes white light and is supplied to the illumination optical system 3.

In the light source device of FIG. 5A described above, among the light based on the blue light emitted by the blue laser light source 21, the light component that does not reach the illumination optical system 3 due to the spectral characteristics of the polarization separation mirror 24B is , Only 10% (S polarization component) of the blue diffused light transmitted through the polarization separation mirror 24B. Since the blue diffused light is originally based on 20% of the 100% of the blue light emitted by the light source 21 that has passed through the polarization separation mirror 24B, it does not reach the illumination optical system 3 through the polarization separation mirror 24B. The "10%" blue diffused light is about 0.2 × 0.1 = 0.02 = 2% of the 100% of the blue light emitted by the light source 21. Therefore, the light utilization efficiency of the light source device (A) of FIG. 2 utilizing the spectral characteristics of the polarization separation mirror 24B is very high.

Further, since the spectral characteristics of the polarization separation mirror 24B are used, S-polarized light may remain in the optical path from the light source to the polarization separation mirror 24B, and a retardation plate as shown in FIG. 6 of Patent Document 1 is arranged. No need. Therefore, it can be configured inexpensively. Similarly, since the spectral characteristics of the polarizing separation mirror 24B are used, the diffused light from the diffuser plate may be in an unpolarized state in the optical path from the diffuser plate to the polarization separation mirror 24B, and Patent Document 1 It is not necessary to arrange the retardation plate as shown in FIGS. 2 and 6. Therefore, it can be configured inexpensively. Further, the diffusion of the diffusion plate may be natural diffusion, and it is not necessary to use a special diffusion plate for maintaining the polarized state, and the diffusion plate can be constructed at low cost.

Even when the light source device of FIG. 5 (A) and the projection type image display device using the light source device according to the second embodiment of the present invention described above use a light source that emits blue S polarized light, FIG. 5 ( B) By using the polarization separation mirror 24B having the spectral characteristics described in (C), it is possible to obtain the same effect as that described in FIGS. 5 and 6 of the first embodiment.

(Embodiment 3)
Next, Embodiment 3 of the present invention will be described.

In the projection type image display device according to the third embodiment of the present invention, the internal configuration of the light source device 2 of the projection type image display device 1 according to the first embodiment of the present invention is shown in FIGS. 7 and 7 from the configurations of FIGS. 2 and 3. It is changed to the configuration of 8.

In the description of the third embodiment, the repeated description of the configuration having the same function as the function described in the first embodiment will be omitted. Therefore, in the following description, only the part different from the first embodiment will be described. The configurations and processes not mentioned in the following description of the third embodiment are the same as those of the first embodiment.

FIG. 7A describes the details of the light source device 2 according to the third embodiment. The light source device 2 according to the third embodiment is different from the light source device 2 according to the first embodiment in the positions where the diffuser plate and the phosphor are arranged.

In FIG. 7A, the light source 21 is a blue laser (BL), and P-polarized blue light (B light), which is laser light, is emitted along the optical axis 1. In the example of this figure, the laser light of the light source 21 has a main wavelength of around 455 nm. Then, the reflection mirror 29 reflects the P-polarized light of blue light, and the polarization separation mirror 24C is irradiated with blue light. The polarization separation mirror 24C separates blue P-polarized light into 80% and 20% according to predetermined spectral characteristics (transmission characteristics and reflection characteristics).

In the example of FIG. 7A, 80% of the blue P-polarized light that is the laser light in the polarization separation mirror 24C is transmitted, passes through the condenser lens 27B, and reaches the phosphor 28B. Fluorescence is generated by irradiating the phosphor 28B with blue laser light which is excitation light. In the example of (A) of FIG. 7, the fluorescence spectrum contains light of at least 500 nm to 620 nm. The fluorescence emitted by the phosphor 28B is emitted at a wide angle, but is condensed by the condenser lens 27B to become a fluorescent luminous flux, which is incident on the polarization separation mirror 24C again, is reflected by the polarization separation mirror 24C, and is incident on the illumination optical system 3. do. The detailed polarization state from the phosphor 28B to the reflection of the polarization separation mirror 24C and the incident on the illumination optical system 3 will be described later.

On the other hand, in the example of FIG. 7A, 20% of the blue P polarized light, which is the laser light, is reflected by the polarization separation mirror 24C, passes through the condenser lens 25B, and is incident on the diffuser plate 26B. The blue P-polarized light is naturally diffusely reflected by the diffuser plate 26B to become a wide-angle light flux, which is incident on the condenser lens 25B again, and is condensed by the condenser lens 25B to become a blue light flux, which is again incident on the polarization separation mirror 24C. The polarization separation mirror 24C reflects and transmits a blue light flux incident from the diffuser plate 26B side with predetermined spectral characteristics. Of these, the transmitted blue light flux is incident on the illumination optical system 3. The detailed polarization state of the luminous flux from the diffuser plate 26B to the light transmitted through the polarization separation mirror 24C and incident on the illumination optical system 3 will be described later.

Next, using (B) and (C) of FIG. 7, the spectral characteristics (transmittance and reflectance characteristics) of the polarization separation mirror 24C in the example of FIG. 7 are shown. FIG. 7B is an example of transmittance, and FIG. 7C is an example of reflectance.

The polarization separation mirror 24C in the example of FIG. 7 has a wavelength range related to the fluorescence spectrum of the phosphor (hereinafter, fluorescence spectrum wavelength band) in both the transmittance characteristics of FIG. 7B and the reflectance characteristics of FIG. 7C. In the range of 500 nm to 620 nm (also referred to as), the reflectance characteristic of P-polarized light and the spectral ratio characteristic of S-polarized light having a polarization direction orthogonal to the polarization direction of P-polarized light are substantially equal. Specifically, as shown in FIG. 7B, both P-polarized light and S-polarized light have an average transmittance of 5% or less and have characteristics as close to 0% as possible. That is, as shown in FIG. 7C, both P-polarized light and S-polarized light have an average reflectance of 95% or more, and have characteristics as close to 100% as possible. That is, the polarization separation mirror 24C has a characteristic that both P-polarized light and S-polarized light reflect as much light as possible in the wavelength range of 500 nm to 620 nm.

On the other hand, regarding the spectral characteristics near 455 nm, which is the main wavelength of the blue laser light from the light source, the spectral characteristics of P-polarized light and the spectral characteristics of S-polarized light have different characteristics. Specifically, as shown in FIG. 7B, the transmittance of S-polarized light near 455 nm is 95% or more, and has a characteristic as close to 100% as possible. On the other hand, the transmittance of P-polarized light near 455 nm is about 80% (for example, 80 ± 5%), and has a reflectance characteristic different from that of S-polarized light. That is, as shown in FIG. 7 (C), the reflectance of S-polarized light near 455 nm is 5% or less, and has a characteristic as close to 0% as possible. On the other hand, the reflectance of P-polarized light near 455 nm is about 20% (for example, 20 ± 5%), and has a transmittance characteristic different from that of S-polarized light.

As described above, the polarization separation mirror 24C used in the example of FIG. 7 of the present embodiment has the same spectral characteristics of P polarization and S polarization in the wavelength range related to the fluorescence spectrum of the phosphor (for example, 500 nm to 620 nm). Then, the spectral characteristics of P-polarization and the spectral characteristics of S-polarization in the vicinity of the main wavelength (near 455 nm) of the blue laser light as the light source are made different. Specifically, it has a spectral characteristic in which the transmittance of P-polarized light near 455 nm is about 80% of the transmittance of S-polarized light. In this case, about 80% may be included in the range of, for example, 80 ± 5%. Within this range, at least it functions sufficiently as a light source of the present embodiment.

The details of the polarization state of each light flux in the light source device of FIG. 7 (A) using the spectral characteristics of the polarization separation mirror 24C described above will be described with reference to FIG.

FIG. 8A shows the color and polarization state of the light beam before it is incident on the polarization separation mirror 24C, and the color and polarization of the light transmitted through the polarization separation mirror 24C, where the amount of blue laser light emitted by the light source 21 is 100%. It is a figure explaining the state, the color of the light reflected by the polarization separation mirror 24C, and the polarization state. Specifically, the color and polarization state of the light flux before it is incident on the polarization separation mirror 24C are blue light emitted by the light source 21 and are in a P-polarized state of 100%. On the other hand, the color and polarization state of the light transmitted through the polarization separation mirror 24C are P-polarized blue light due to the spectral characteristics of the polarization separation mirror 24A described in FIGS. It is 80% before the polarization separation mirror 24C is incident.

Further, the color and polarization state of the light reflected by the polarization separation mirror 24C are P-polarized light of blue light due to the spectral characteristics of the polarization separation mirror 24C described with reference to FIGS. 7 (B) and 7 (C), and the amount of light thereof is polarization separation. It is 20% before the mirror 24C is incident. That is, in the configuration of FIG. 7A, the polarization separation mirror 24C has a function of separating P-polarized light at a ratio of 4: 1 which is blue light emitted by the light source 21 due to the above spectral characteristics.

Next, in FIG. 8B, assuming that the amount of light emitted by the phosphor 28B is 100%, the color and polarization state of the fluorescent light flux before being incident on the polarization separation mirror 24C and the fluorescence light flux transmitted through the polarization separation mirror 24C are shown. A description of the color and polarization states is given. Specifically, the color and polarization state of the fluorescence light beam before it is incident on the polarization separation mirror 24C is yellow fluorescence emitted by the phosphor 28B, and the polarization state is unpolarized, that is, the P polarization component is 50% and the S polarization component is. It is in a 50% state.

Further, the color and polarization state of the fluorescent light flux transmitted through the polarization separation mirror 24C are such that yellow fluorescence is reflected almost as it is due to the spectral characteristics of the polarization separation mirror 24C described in FIGS. 7B and 7C, and the illumination optical system 3 Proceed towards. Therefore, the polarized state of yellow fluorescence reflected by the polarization separation mirror 24C remains unpolarized, that is, the P-polarized light component is 50% and the S-polarized light component is 50%. That is, the spectral characteristics of the polarization separation mirror 24C have a function of reflecting the unpolarized yellow fluorescence emitted by the phosphor 28B in the unpolarized state in the configuration of FIG. 7A.

Next, in FIG. 8B, assuming that the amount of blue diffused light diffused by the diffuser plate 26B is 100%, the color and polarization state of the blue diffused light before it is incident on the polarization separation mirror 24C, and the polarization separation mirror. An explanation of the color and polarization state of the blue diffused light transmitted through the 24C and the color and polarization state of the blue diffused light reflected by the polarization separation mirror 24C are shown. Specifically, the color and polarization state of the diffused light before it is incident on the polarization separation mirror 24C is the blue diffused light diffused by the diffuser plate 26B, and the polarization state is unpolarized, that is, the S polarization component is 50% and the P polarization component. Is in the state of 50%.

Further, the color and polarization state of the blue diffused light transmitted by the polarization separation mirror 24C are determined by the spectral characteristics of the polarization separation mirror 24C described in FIGS. It is transmitted almost as it is. Of the 50% of the P-polarized light component of the blue diffused light, 40% is transmitted and 10% is reflected. That is, the spectral characteristics of the polarization separation mirror 24C are such that in the configuration of FIG. 7A, 10% (a part of the P polarization component) of the amount of blue diffused light diffused by the diffuser plate 26B is the polarization separation mirror 24C. Although it cannot reach the illumination optical system 3 due to reflection, the remaining 90% of the light (S polarization component 50% and P polarization component 40%) is transmitted and travels toward the illumination optical system 3.

The yellow fluorescence reflected from the polarization separation mirror 24C (unpolarized light with P polarization component 50% and S polarization component 50%) and the blue diffused light transmitted through the polarization separation mirror 24C (S polarization component 50% and P polarization component) described above 40%) of the combined light becomes white light and is supplied to the illumination optical system 3.

In the light source device of FIG. 7 (A) described above, among the light based on the blue light emitted by the blue laser light source 21, the light component that does not reach the illumination optical system 3 due to the spectral characteristics of the polarization separation mirror 24C is , Only 10% (P polarization component) of the blue diffused light reflected by the polarization separation mirror 24C. Since the blue diffused light is originally based on 20% of the 100% blue light emitted by the light source 21 that is reflected by the polarization separation mirror 24C, it reflects the polarization separation mirror 24C and does not reach the illumination optical system 3. The “10%” blue diffused light is about 0.2 × 0.1 = 0.02 = 2% of the 100% of the blue light emitted by the light source 21. Therefore, the light utilization efficiency of the light source device (A) of FIG. 7 utilizing the spectral characteristics of the polarization separation mirror 24C is very high.

Further, since the spectral characteristics of the polarization separation mirror 24C are used, P-polarized light may remain in the optical path from the light source to the polarization separation mirror 24C, and a retardation plate as shown in FIG. 6 of Patent Document 1 is arranged. No need. Therefore, it can be configured inexpensively.

Similarly, since the spectral characteristics of the polarizing separation mirror 24C are used, the diffused light from the diffuser plate may be in an unpolarized state in the optical path from the diffuser plate to the polarization separation mirror 24C, and Patent Document 1 It is not necessary to arrange the retardation plate as shown in FIGS. 2 and 6. Therefore, it can be configured inexpensively. Further, the diffusion of the diffusion plate may be natural diffusion, and it is not necessary to use a special diffusion plate for maintaining the polarized state, and the diffusion plate can be constructed at low cost.

The light source device of FIG. 7 (A) according to the third embodiment of the present invention described above and the projection type image display device using the light source device are the light source device of FIG. 2 (A) according to the first embodiment. On the other hand, even when the arrangement of the phosphor and the diffuser plate is exchanged, by using the polarization separation mirror 24C having the spectral characteristics described in FIGS. 7 (B) and 7 (C), FIGS. An effect equivalent to the effect described in 6 can be obtained.

Further, in the projection type image display device using the light source device of FIG. 7A, the ratio of P-polarized light in the blue diffused light directed to the illumination optical system 3 is relatively lower than that of S-polarized light as shown in FIG. As a result, the projection type image display device using the light source device of FIG. 7A is the projection type image display device described in FIG. 4 of the first embodiment in addition to the effects described in FIGS. 7 and 8. It has the effect of further reducing the deterioration of optical components over time and extending the life of the optical components.

(Embodiment 4)
Next, Embodiment 4 of the present invention will be described.

In the projection type image display device according to the fourth embodiment of the present invention, the internal configuration of the light source device 2 of the projection type image display device 1 according to the third embodiment of the present invention is shown in FIGS. It is changed to the configuration of 10.

In the description of the fourth embodiment, the repeated description of the configuration having the same function as the function described in the third embodiment will be omitted. Therefore, in the following description, only the parts different from the third embodiment will be described. The configurations and processes not mentioned in the following description of the fourth embodiment are the same as those of the third embodiment.

FIG. 9A describes the details of the light source device 2 according to the fourth embodiment.

In FIG. 9A, the light source 21 is a blue laser (BL), and S-polarized blue light (B light), which is laser light, is emitted along the optical axis 1. In the fourth embodiment, the blue laser light emitted by the light source 21 is S-polarized light, which is different from the first embodiment. In the example of this figure, the laser light of the light source 21 has a main wavelength of around 455 nm. Then, the S-polarized light of blue light is reflected by the reflection mirror 29, and the polarized light separation mirror 24D is irradiated with blue light. The polarization separation mirror 24D separates blue S polarized light into 80% and 20% according to predetermined spectral characteristics (transmission characteristics and reflection characteristics).

In the example of FIG. 9A, 80% of the blue S-polarized light that is the laser light in the polarization separation mirror 24D is transmitted, passes through the condenser lens 27B, and reaches the phosphor 28B. Fluorescence is generated by irradiating the phosphor 28B with blue laser light which is excitation light. In the example of (A) of FIG. 9, the fluorescence spectrum contains light of at least 500 nm to 620 nm. The fluorescence emitted by the phosphor 28B is emitted at a wide angle, but is condensed by the condenser lens 27B to become a fluorescent luminous flux, which is incident on the polarization separation mirror 24D again, is reflected by the polarization separation mirror 24D, and is incident on the illumination optical system 3. do. The detailed polarization state from the phosphor 28B to the light transmitted through the polarization separation mirror 24D and incident on the illumination optical system 3 will be described later.

On the other hand, in the example of FIG. 9A, 20% of the blue S polarized light, which is the laser light, is reflected by the polarization separation mirror 24D, passes through the condenser lens 25B, and is incident on the diffuser plate 26B. The blue S polarized light is naturally diffusely reflected by the diffuser plate 26B to become a wide-angle light flux, which is incident on the condenser lens 25B again, and is condensed by the condenser lens 25B to become a blue light flux, which is again incident on the polarization separation mirror 24D. The polarization separation mirror 24D reflects and transmits a blue light flux incident from the diffuser plate 26B side with predetermined spectral characteristics. Of these, the transmitted blue light flux is incident on the illumination optical system 3. The detailed polarization state of the light flux from the diffuser plate 26B to the light reflected by the polarization separation mirror 24D and incident on the illumination optical system 3 will be described later.

Next, using (B) and (C) of FIG. 9, the spectral characteristics (transmittance and reflectance characteristics) of the polarization separation mirror 24D in the example of FIG. 9 are shown. The polarization separation mirror 24D in the example of FIG. 9 has different spectral characteristics from the polarization separation mirror 24C of the third embodiment because it corresponds to the blue S polarization from the light source. Here, (B) of FIG. 9 is an example of transmittance, and (C) of FIG. 9 is an example of reflectance.

The polarization separation mirror 24D in the example of FIG. 9 has a wavelength range related to the fluorescence spectrum of the phosphor (hereinafter, fluorescence spectrum wavelength band) in both the transmittance characteristics of FIG. 9B and the reflectance characteristics of FIG. 9C. In the range of 500 nm to 620 nm (also referred to as), the reflectance characteristic of S-polarized light and the spectral ratio characteristic of P-polarized light having a polarization direction orthogonal to the polarization direction of S-polarized light are substantially equal. Specifically, as shown in FIG. 9B, both S-polarized light and P-polarized light have an average transmittance of 5% or less and have characteristics as close to 0% as possible. That is, as shown in FIG. 9C, both S-polarized light and P-polarized light have an average reflectance of 95% or more, and have characteristics as close to 100% as possible. That is, the polarization separation mirror 24D has a characteristic that both S-polarized light and P-polarized light reflect as much light as possible in the wavelength range of 500 nm to 620 nm.

On the other hand, regarding the spectral characteristics near 455 nm, which is the main wavelength of the blue laser light from the light source, the spectral characteristics of S-polarized light and the spectral characteristics of P-polarized light have different characteristics. Specifically, as shown in FIG. 9B, the transmittance of P-polarized light near 455 nm is 95% or more, and has a characteristic as close to 100% as possible. On the other hand, the transmittance of S-polarized light near 455 nm is about 80% (for example, 80 ± 5%), and has a reflectance characteristic different from that of P-polarized light. That is, as shown in FIG. 9C, the reflectance of P-polarized light near 455 nm is 5% or less, and has a characteristic as close to 0% as possible. On the other hand, the reflectance of S-polarized light near 455 nm is about 20% (for example, 20 ± 5%), and has a transmittance characteristic different from that of P-polarized light.

As described above, the polarization separation mirror 24D used in the example of FIG. 9 of the present embodiment has the same spectral characteristics of S polarization and P polarization in the wavelength range related to the fluorescence spectrum of the phosphor (for example, 500 nm to 620 nm). Then, the spectral characteristics of S polarization and the spectral characteristics of P polarization in the vicinity of the main wavelength (near 455 nm) of the blue laser light as the light source are made different. Specifically, it has a spectral characteristic in which the transmittance of S-polarized light near 455 nm is about 80% of the transmittance of P-polarized light. In this case, about 80% may be included in the range of, for example, 80 ± 5%. Within this range, at least it functions sufficiently as a light source of the present embodiment.

The details of the polarization state of each light flux in the light source device of FIG. 9A using the spectral characteristics of the polarization separation mirror 24D described above will be described with reference to FIG.

FIG. 10A shows the color and polarization state of the light beam before it is incident on the polarization separation mirror 24D, and the color and polarization of the light transmitted through the polarization separation mirror 24D, assuming that the amount of blue laser light emitted by the light source 21 is 100%. It is a figure explaining the state, the color of the light reflected by the polarization separation mirror 24D, and the polarization state. Specifically, the color and polarization state of the light beam before it is incident on the polarization separation mirror 24D is the blue light emitted by the light source 21 and is in the state of 100% S polarization. On the other hand, the color and polarization state of the light transmitted through the polarization separation mirror 24D are S-polarized blue light due to the spectral characteristics of the polarization separation mirror 24D described in FIGS. 9B and 9C, and the amount of light thereof is S-polarized light. It is 80% before the polarization separation mirror 24D is incident. Further, the color and polarization state of the light reflected by the polarization separation mirror 24D are S-polarized light of blue light due to the spectral characteristics of the polarization separation mirror 24D described with reference to FIGS. 10 (B) and 10 (C), and the amount of light thereof is polarization separation. It is 20% before the mirror 24D is incident. That is, in the configuration of FIG. 10A, the polarization separation mirror 24D has a function of separating S-polarized light at a ratio of 4: 1 which is blue light emitted by the light source 21 due to the above spectral characteristics.

Next, in FIG. 10B, assuming that the amount of light emitted by the phosphor 28B is 100%, the color and polarization state of the fluorescent light flux before being incident on the polarization separation mirror 24D and the fluorescence light flux reflected by the polarization separation mirror 24D are shown. A description of the color and polarization states is provided. Specifically, the color and polarization state of the fluorescence light beam before it is incident on the polarization separation mirror 24D is yellow fluorescence emitted by the phosphor 28B, and the polarization state is unpolarized, that is, the S polarization component is 50% and the P polarization component is. It is in a 50% state. Further, the color and polarization state of the fluorescent light beam reflected by the polarization separation mirror 24D are such that yellow fluorescence is reflected almost as it is due to the spectral characteristics of the polarization separation mirror 24D described in FIGS. 9B and 9C, and the illumination optical system 3 Proceed towards. Therefore, the polarized state of yellow fluorescence reflected by the polarization separation mirror 24D remains unpolarized, that is, the S-polarized light component is 50% and the P-polarized light component is 50%. That is, the spectral characteristics of the polarization separation mirror 24D have a function of transmitting unpolarized yellow fluorescence emitted by the phosphor 28B in an unpolarized state in the configuration of FIG. 9A.

Next, in FIG. 10B, assuming that the amount of blue diffused light diffused by the diffuser plate 26B is 100%, the color and polarization state of the blue diffused light before it is incident on the polarization separation mirror 24D, and the polarization separation mirror. An explanation of the color and polarization state of the blue diffused light transmitted through the 24D and the color and polarization state of the blue diffused light reflected by the polarization separation mirror 24D are shown. Specifically, the color and polarization state of the diffused light before it is incident on the polarization separation mirror 24D is the blue diffused light diffused by the diffuser plate 26B, and the polarization state is unpolarized, that is, the P polarization component is 50% and the S polarization component. Is in the state of 50%.

Further, the color and polarization state of the blue diffused light transmitted by the polarization separation mirror 24D are determined by the spectral characteristics of the polarization separation mirror 24D described in FIGS. 9B and 9C, with respect to 50% of the P polarization component of the blue diffused light. It is transmitted almost as it is. Of the 50% of the S-polarized light component of the blue diffused light, 40% is transmitted and 10% is reflected. That is, the spectral characteristics of the polarization separation mirror 24D show that, in the configuration of FIG. 9A, 10% (a part of the S polarization component) of the amount of blue diffused light diffused by the diffuser plate 26B is the polarization separation mirror 24D. Although it cannot reach the illumination optical system 3 due to reflection, the remaining 90% of the light (P polarization component 50% and S polarization component 40%) is transmitted and travels toward the illumination optical system 3.

The yellow fluorescence reflected from the polarization separation mirror 24D (unpolarized light with 50% S polarization component and 50% P polarization component) and the blue diffused light transmitted through the polarization separation mirror 24D (P polarization component 50% and S polarization component) described above. 40%) of the combined light becomes white light and is supplied to the illumination optical system 3.

In the light source device of FIG. 9A described above, among the light based on the blue light emitted by the blue laser light source 21, the light component that does not reach the illumination optical system 3 due to the spectral characteristics of the polarization separation mirror 24D is included. , Only 10% (S polarization component) of the blue diffused light reflected by the polarization separation mirror 24D. Since the blue diffused light is originally based on 20% of the 100% blue light emitted by the light source 21 that is reflected by the polarization separation mirror 24D, it reflects the polarization separation mirror 24D and does not reach the illumination optical system 3. The “10%” blue diffused light is about 0.2 × 0.1 = 0.02 = 2% of the 100% of the blue light emitted by the light source 21. Therefore, the light utilization efficiency of the light source device (A) of FIG. 9 utilizing the spectral characteristics of the polarization separation mirror 24D is very high.

Further, since the spectral characteristics of the polarization separation mirror 24D are used, S-polarized light may remain in the optical path from the light source to the polarization separation mirror 24D, and a retardation plate as shown in FIG. 6 of Patent Document 1 is arranged. No need. Therefore, it can be configured inexpensively.

Similarly, since the spectral characteristics of the polarizing separation mirror 24D are used, the diffused light from the diffuser plate may be in an unpolarized state in the optical path from the diffuser plate to the polarization separation mirror 24D, and Patent Document 1 It is not necessary to arrange the retardation plate as shown in FIGS. 2 and 6. Therefore, it can be configured inexpensively. Further, the diffusion of the diffusion plate may be natural diffusion, and it is not necessary to use a special diffusion plate for maintaining the polarized state, and the diffusion plate can be constructed at low cost.

The light source device of FIG. 9A according to the fourth embodiment of the present invention described above and the projection type image display device using the light source device are shown in FIG. 9 even when a light source that emits blue S-polarized light is used. B) By using the polarization separation mirror 24D having the spectral characteristics described in (C), it is possible to obtain the same effect as that described in FIGS. 7 and 8 of the third embodiment.

In the light source devices of all the embodiments described above, "the blue light source emits blue polarized light in the first polarization direction, which is S-polarized light or P-polarized light. The spectral characteristics of the polarization separation mirror are incident. When the spectral rate for splitting light into the reflected light path is defined as the reflectance and the spectral rate for splitting incident light into the transmitted light path is defined as the transmittance, either the reflectance or the transmittance is defined at the main wavelength of the blue light source. With respect to the first transmittance, which is the spectral rate, the first spectral rate with respect to the first polarization direction is relative to the first spectral rate with respect to the second polarization direction orthogonal to the first polarization direction. In the fluorescence spectrum wavelength band having a green light band and a red band, the transmittance in the first polarization direction and the transmittance in the second polarization direction are substantially equal. " Both are common.

Further, although the fluorescence spectrum wavelength band is set to 500 nm to 620 nm in the above description of all the embodiments, it may be expanded to about 500 nm to 650 nm.

In the description of all the above embodiments, an example in which the main wavelength of the blue light source of the light source 21 is 455 nm has been described. However, the main wavelength of the blue light source of the light source 21 is not limited to 455 nm, and any blue light source such as 450 nm or 460 nm may be adopted. In that case, the explanation of the spectral characteristics of 455 nm in the explanations of the spectral characteristics of the polarizing separation mirrors 24A to D described above in each embodiment can be replaced with the explanation of the spectral characteristics at the main wavelength of the blue light source adopted above. good.

1: Optical system, 2: Light source device, 3: Illumination optical system, 4: Color separation optical system, 5R, 5G, 5B: Condenser lens, 6R, 6G, 6B: Image display element, 7: Photosynthetic prism, 8: Projection Lens, 9: screen, 21: light source, 24A, 24B, 24C, 24D: polarization separation mirror, 25A, 25B, 27A, 27B: condenser lens, 26A, 26B: diffuser, 28A, 28B: phosphor, 29: reflection Mirror, 31, 32: Array lens, 33: Polarization conversion element, 34: Condensing lens, 41B, 41G: Dycroic mirror, 42a, 42b, 42c: Reflective mirror, 43, 44: Relay lens, 100: Projection type image display Device.

Claims (18)

A projection type image display device having a light source device that generates white light based on light emitted from a blue light source.
With the blue light source
Polarization separation mirror and
Fluorescent material and
Diffusing plate and
Illumination optics and
A display element that transmits or reflects light from the illumination optical system,
A projection optical system that projects light from the display element,
With
The blue light source emits blue polarized light in the first polarization direction, which is S-polarized light or P-polarized light.
The spectral characteristics of the polarizing separation mirror are
When the spectral rate at which the incident light is separated into the reflected light path is defined as the reflectance and the spectral rate at which the incident light is separated into the transmitted light path is defined as the transmittance, either the reflectance or the transmittance is defined at the main wavelength of the blue light source. With respect to the first transmittance, which is one of the spectral rates, the first spectral rate with respect to the first polarization direction and the first spectral rate with respect to the second polarization direction orthogonal to the first polarization direction. Approximately 80%
In the fluorescence spectrum wavelength band having a green light band and a red band, the transmittance in the first polarization direction and the transmittance in the second polarization direction are substantially equal to each other.
Projection type video display device. In the projection type image display device according to claim 1,
The blue light source emits blue light.
The polarization separation mirror disperses blue light from the blue light source into different luminous fluxes traveling in different optical paths.
The phosphor receives a light flux of the first blue light spectroscopically separated from the polarization separation mirror and emits yellow fluorescence.
The diffuser plate receives and diffuses a light flux of the second blue light dispersed from the polarization separation mirror to generate blue diffused light.
The yellow fluorescence and the blue diffused light are incident on the polarization separation mirror, and white light incident on the illumination optical system is formed based on the yellow fluorescence and the blue diffused light.
Projection type video display device. In the projection type image display device according to claim 2,
The polarization state of the blue light emitted by the blue light source remains the first polarization direction in the optical path from the blue light source to the polarization separation mirror.
Projection type video display device. In the projection type image display device according to claim 2 or 3.
The blue diffused light is in an unpolarized state in the optical path from the diffuser plate to the polarization separation mirror.
Projection type video display device. In the projection type image display device according to claim 2,
The first spectral rate is the reflectance, which is
The phosphor is arranged at a position where it receives the light flux of the first blue light dispersed by reflection from the polarization separation mirror.
The diffuser plate is arranged at a position where it receives the light flux of the second blue light dispersed by transmission from the polarization separation mirror.
Projection type video display device. In the projection type image display device according to claim 5,
The first polarization direction is P-polarized light.
In the polarization component of white light incident on the illumination optical system, P-polarized light is less than S-polarized light.
The illumination optical system includes a polarization conversion element that converts P-polarized light contained in white light incident on the illumination optical system into S-polarized light.
Projection type video display device. In the projection type image display device according to claim 2,
The first spectral rate is the transmittance.
The phosphor is arranged at a position where it receives the light flux of the first blue light dispersed by transmission from the polarization separation mirror.
The diffuser plate is arranged at a position where it receives the light flux of the second blue light dispersed by reflection from the polarization separation mirror.
Projection type video display device. In the projection type image display device according to claim 7.
The first polarization direction is P-polarized light.
In the polarization component of white light incident on the illumination optical system, P-polarized light is less than S-polarized light.
The illumination optical system includes a polarization conversion element that converts P-polarized light contained in white light incident on the illumination optical system into S-polarized light.
Projection type video display device. In the projection type image display device according to any one of claims 1 to 8.
The approximately 80% is within the range of 80% ± 5%.
Projection type video display device. In the projection type image display device according to any one of claims 1 to 8.
The transmittance in the first polarization direction is substantially equal to the transmittance in the second polarization direction, that is, the average transmittance in the wavelength range of 500 nm to 620 nm in the first polarization direction is the second. Within ± 5% of the average transmittance in the polarization direction,
Projection type video display device. A light source device that generates white light based on the light emitted from a blue light source.
With the blue light source
Polarization separation mirror and
Fluorescent material and
Diffusing plate and
With
The blue light source emits blue polarized light in the first polarization direction, which is S-polarized light or P-polarized light.
The spectral characteristics of the polarizing separation mirror are
When the spectral rate at which the incident light is separated into the reflected light path is defined as the reflectance and the spectral rate at which the incident light is separated into the transmitted light path is defined as the transmittance, either the reflectance or the transmittance is defined at the main wavelength of the blue light source. With respect to the first transmittance, which is one of the spectral rates, the first spectral rate with respect to the first polarization direction and the first spectral rate with respect to the second polarization direction orthogonal to the first polarization direction. Approximately 80%
In the fluorescence spectrum wavelength band having a green light band and a red band, the transmittance in the first polarization direction and the transmittance in the second polarization direction are substantially equal to each other.
Light source device. In the light source device according to claim 11,
The blue light source emits blue light.
The polarization separation mirror disperses blue light from the blue light source into different luminous fluxes traveling in different optical paths.
The phosphor receives a light flux of the first blue light spectroscopically separated from the polarization separation mirror and emits yellow fluorescence.
The diffuser plate receives and diffuses a light flux of the second blue light dispersed from the polarization separation mirror to generate blue diffused light.
The yellow fluorescence and the blue diffused light are incident on the polarization separation mirror, and white light emitted from the light source device is formed based on the yellow fluorescence and the blue diffused light.
Light source device. In the light source device according to claim 12,
The polarization state of the blue light emitted by the blue light source remains the first polarization direction in the optical path from the blue light source to the polarization separation mirror.
Light source device. In the light source device according to claim 12 or 13.
The blue diffused light is in an unpolarized state in the optical path from the diffuser plate to the polarization separation mirror.
Light source device. In the light source device according to claim 12,
The first spectral rate is the reflectance, which is
The phosphor is arranged at a position where it receives the light flux of the first blue light dispersed by reflection from the polarization separation mirror.
The diffuser plate is arranged at a position where it receives the light flux of the second blue light dispersed by transmission from the polarization separation mirror.
Light source device. In the light source device according to claim 12,
The first spectral rate is the transmittance.
The phosphor is arranged at a position where it receives the light flux of the first blue light dispersed by transmission from the polarization separation mirror.
The diffuser plate is arranged at a position where it receives the light flux of the second blue light dispersed by reflection from the polarization separation mirror.
Light source device. The light source device according to any one of claims 11 to 16.
The approximately 80% is within the range of 80% ± 5%.
Light source device. The light source device according to any one of claims 11 to 16.
The transmittance in the first polarization direction is substantially equal to the transmittance in the second polarization direction, that is, the average transmittance in the wavelength range of 500 nm to 620 nm in the first polarization direction is the second. Within ± 5% of the average transmittance in the polarization direction,
Light source device.

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