Projector

Abstract

The invention provides a projector capable of more appropriately generating white light from a laser light source for image display. A white light generation unit that generates white light from blue light and yellow light has a dichroic mirror to which blue light from blue laser light is irradiated, a first condenser lens that condenses the blue light that has passed through the dichroic mirror, and a diffusion plate that diffuses the condensed blue light. A second condensing lens that condenses blue light obtained by passing the diffused blue light through a dichroscope; and a phosphor that emits yellow light by being irradiated with the condensed blue light. The diffusion plate is an alumina ceramic plate. The dichroic mirror has a first region through which one of blue light and yellow light is transmitted and the other is reflected, and a second region through which both the blue light and the yellow light are reflected or transmitted, the blue light and the yellow light included in the white light are respectively diffused blue light transmitted through the first condenser lens, and the yellow light from the phosphor is transmitted through the second condenser lens. And then passing through a dichroscope.

Description

[0001] This application is a divisional application of the invention patent application filed on January 23, 2019, with application number 201980006216.X and entitled "Projector". Technical Field

[0002] This invention relates to a projector that uses a laser light source. Background Technology

[0003] Background technology for projectors that use lasers in their light sources includes Patent Document 1. Patent Document 1 discloses a projector that uses blue light from a laser light source and yellow fluorescence containing red and green light to generate white light in image display. It discloses that two blue laser light sources are required; blue light from a first blue laser light source is reflected; and a dichroic mirror is used to transmit yellow fluorescence emitted from a fluorescent panel as excitation light from a second blue laser light source, thereby synthesizing blue light and yellow fluorescence to generate white light.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-15966 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In Patent Document 1, blue lasers need to be configured in two different locations, without considering the issues of high cost and increased size of the light source device.

[0009] The purpose of this invention is to provide a projector that can more appropriately generate white light from a laser light source.

[0010] Technical solutions for solving the problem

[0011] The present invention was made in view of the aforementioned background technology and problems. One example is a projector comprising: a white light generating unit that uses a blue laser as a light source to generate blue light and yellow light, thereby generating white light containing the generated blue and yellow light; and an optical system that modulates the light from the white light generated by the white light generating unit using an image display element and projects the modulated light. The white light generating unit includes: a dichroic mirror irradiated with blue light from the blue laser as a light source; a first focusing lens that focuses the blue light reflected or transmitted from the dichroic mirror; a diffuser plate that diffuses the blue light focused by the first focusing lens; and a focusing plate that focuses the blue light transmitted or reflected from the dichroic mirror. The system includes a second condensing lens and a phosphor that emits yellow light from blue light condensed by the second condensing lens. The diffuser is an alumina ceramic plate. The dichroic mirror has a first region and a second region. The first region has the property of transmitting one of the blue light and yellow light while reflecting the other. The second region has the property of reflecting or transmitting both the blue light and yellow light. The blue light contained in the white light output by the white light generating unit is obtained by the blue light diffused by the diffuser being transmitted through the first condensing lens and then reflected or transmitted by the dichroic mirror. The yellow light contained in the white light output by the white light generating unit is obtained by the yellow light emitted from the phosphor being transmitted through the second condensing lens and then reflected or transmitted by the dichroic mirror.

[0012] The effects of the invention

[0013] According to the present invention, a projector is provided that can more appropriately generate white light from a laser light source for image display. Attached Figure Description

[0014] Figure 1 This is a structural diagram showing the optical system of the projector in Embodiment 1.

[0015] Figure 2A This is a structural diagram of the light source device in Embodiment 1 and a diagram showing the transmission and reflection characteristics of the dichroic mirror.

[0016] Figure 2B This is an example of the emission spectrum of the blue laser in Example 1.

[0017] Figure 2C This is an example of the emission spectrum of the yellow phosphor in Example 1.

[0018] Figure 3 This is a diagram illustrating the principle of achieving high efficiency in B-light utilization through the segmentation of the transmission and reflection regions of the dichroic mirror in Example 1.

[0019] Figure 4This is a diagram showing the coating method and transmittance characteristics of the B-transmission and Y-reflection regions and the total reflection region of the dichroic mirror in Example 1.

[0020] Figure 5 This is a structural diagram of the light source device in Embodiment 2 and a diagram showing the transmission and reflection characteristics of the dichroic mirror.

[0021] Figure 6 This is a diagram showing the coating method for the B-reflection and Y-transmission regions and the total transmission region of the dichroic mirror of Example 2, as well as the transmittance characteristics of each region.

[0022] Figure 7 This is a structural diagram of the light source device in Embodiment 3 and a diagram showing the transmission and reflection characteristics of the dichroic mirror.

[0023] Figure 8 This is a diagram showing the illuminance distribution of the diffuser plates in Examples 1 to 6.

[0024] Figure 9 This is a diagram illustrating the coating method for the B-transmission and Y-reflection regions and the total reflection region of the dichroic mirror in Example 3.

[0025] Figure 10 This is a structural diagram of the light source device in Embodiment 4 and a diagram showing the transmission and reflection characteristics of the dichroic mirror.

[0026] Figure 11 This is a diagram illustrating the coating method for the B-reflection and Y-transmission regions and the total transmission region of the dichroic mirror in Example 4.

[0027] Figure 12 This is a schematic structural diagram of the light source portion of the light source device in Embodiment 5.

[0028] Figure 13 This is a diagram showing the segmentation structure of the transmission and reflection region of the dichroic mirror in Example 5, which corresponds to Example 1 and its variations.

[0029] Figure 14 This is a diagram showing the segmentation structure of the transmission and reflection region of the dichroic mirror in Example 5, which corresponds to Example 2 and its variations.

[0030] Figure 15 This is a schematic structural diagram of the light source portion of the light source device in Embodiment 6.

[0031] Figure 16 This is a diagram showing the segmentation structure of the transmission and reflection region of the dichroic mirror in Example 6, which corresponds to Example 1 and its variations.

[0032] Figure 17 This is a diagram showing the segmentation structure of the transmission and reflection region of the dichroic mirror in Example 6, which corresponds to Example 2 and its variations.

[0033] Figure 18 This is a schematic diagram showing a cross-sectional view of the alumina ceramic plate used as a diffuser in Example 7.

[0034] Figure 19 This is a diagram illustrating the focusing angle θi of the incident light relative to the diffuser plate and the diffusion angle θo of the outgoing light in Example 7.

[0035] Figure 20 This is a diagram illustrating the definition of the diffusion angle θo of the emitted light from the diffuser plate in Example 7.

[0036] Figure 21 This is an explanatory diagram showing how the regions of the dichroic mirror in Example 7 are converted into circular regions.

[0037] Figure 22 This is a graph showing the optical path near the diffuser plate in Example 7, illustrating the relationship between the focusing angle θi of the incident light, the diffusion angle θo of the outgoing light, and the utilization efficiency of the B light.

[0038] Figure 23 This is a comparison table of the diffusion plate methods in Example 7. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0040] Example 1

[0041] Figure 1 This is a structural diagram illustrating the optical system of the projector in this embodiment. Figure 1 In the projector, the optical system 1 mainly includes a light source device 2, an illumination optical system 3, a color separation optical system 4, image display elements 6R, 6G, and 6B, a light combining prism 7 as a combining optical system, and a projection lens 8 as a projection optical system.

[0042] use Figure 1 The overall operation of the projector's optical system will be explained. The light source device 2 will be explained later, but the white light W beam group (white light W, hereinafter referred to as "W light") obtained from the light source device 2 is the sum of blue light B (blue band light, hereinafter referred to as "B light") and fluorescence Y (yellow light, hereinafter referred to as "Y light"). Here, fluorescence Y refers to yellow fluorescence that also contains green and red bands. The white light W beam group is split into multiple beams by multiple lens units of the multi-lens 31 of the illumination optical system 3, and efficiently guided to the second multi-lens 32 and the polarization conversion element 33. Then, through the polarization conversion element 33, the light is polarized in a predetermined polarization direction. The polarized light is focused by the condenser lens 34 and incident on the dichroic optical system 4.

[0043] In the dichroic optical system 4, white light W is first irradiated by a dichroic mirror 41B. Blue light B (light in the blue frequency band) is reflected, while green light G (light in the green frequency band, hereinafter referred to as "G light") and red light R (light in the red frequency band, hereinafter referred to as "R light") are transmitted. The reflected B light is reflected by mirror 42A and transmitted through condenser lens 5B to the image display element 6B. On the other hand, G light and R light transmitted from dichroic mirror 41G are reflected by dichroic mirror 41B, while R light is transmitted. The reflected G light is transmitted through condenser lens 5G to the image display element 6G. Furthermore, R light transmitted from dichroic mirror 41G is focused by relay lens 43 and then reflected by mirror 42B. The reflected R light is again focused by relay lens 44 and reflected by mirror 42C. The reflected R light is further focused by relay lens 5R and transmitted to the image display element 6R. In each image display element, for incident light, the light intensity is modulated at each pixel according to the image signal (not shown) to form an image, generating reflected or transmitted outgoing light. Additionally, in Figure 1 Examples of transmissive image display elements are disclosed. B-beams, G-beams, and R-beams emitted from each image display element are combined into colored image light by a light-combining prism 7, and then transmitted through a projection lens 8 to a projection screen (not shown). That is, the optical image formed by the image display elements is magnified and projected onto the projection screen (not shown).

[0044] Next, use Figure 2A A detailed description of the light source device 2 in this embodiment will be provided. Figure 2A Will Figure 1 A portion of the light source device 2 is extracted, and a conceptual diagram representing the transmission and reflection characteristics of the dichroic mirror 24 is further plotted at a position corresponding to the optical axis 1. In Figure 2, the light source 21 is a blue laser (BL), emitting blue laser light (B light) centered on the optical axis 1. Furthermore, the B light beam is focused and overlapped by lens 22, and becomes a parallel beam by lens 23. Then, the B light beam is irradiated onto the dichroic mirror 24.

[0045] Here, the dichroic mirror 24 has a region exhibiting B-light transmission and Y-light reflection characteristics as shown in the figure, and also has a total internal reflection region in the central part of the dichroic mirror. That is, the region of the dichroic mirror 24 exhibiting B-light transmission and Y-light reflection characteristics is relatively wide. However, there are regions with total internal reflection characteristics that are partially different from these B-light transmission and Y-light reflection characteristics. In the following description of the present invention, the region occupying a large area in the region of the dichroic mirror where the transmission and reflection characteristics are divided by the region is referred to below as the "wide-area characteristic region". Furthermore, the region with characteristics different from the "wide-area characteristic region" in the partially narrow region is referred to below as the "different characteristic region". Figure 2AIn the examples, the region exhibiting B-light transmission and Y-light reflection characteristics is designated as the "wide-area characteristic region," while the region exhibiting total internal reflection is designated as the "different characteristic region." Furthermore, the B-light transmission and reflection characteristics within the "wide-area characteristic region" can be completely identical. However, to eliminate color unevenness based on the left and right incident angles of light, the shear wavelength (e.g., 50% wavelength) of the dichroic coating can be tilted in the left-right direction. In this case, even with the tilt of the shear wavelength, it is considered part of the "wide-area characteristic region" in the descriptions of the various embodiments of the present invention. Moreover, examples of "different characteristic regions" exhibiting total internal reflection or total transmission characteristics are described in the descriptions of the various embodiments of the present invention. Within a scope that has little impact on the present invention, there is also the possibility of using a dichroic coating for certain reasons. In this case, the transmission and reflection characteristics can also be completely identical within the "different characteristic region," and the shear wavelength (e.g., 50% wavelength) of the dichroic coating can be tilted in the left-right direction to eliminate color unevenness based on the left and right incident angles of light. Again, even with the tilt of the shear wavelength, it is considered part of the "different characteristic region."

[0046] For example, as an illustration, when the proportion of the total internal reflection region (a region with different characteristics) in the B-beam region irradiated by the light source 21 to the dichroic mirror is 20% of the irradiation range of the incident beam, the B-beam irradiated by the dichroic mirror 24 is reflected by about 20% and transmitted by about 80%. That is, about 20% of the central portion of the B-beam irradiated by the light source 21 to the dichroic mirror 24 is reflected.

[0047] The B-beam reflected by the dichroic mirror 24 is focused by the condenser lens 25 and directed onto the diffuser plate 26. Furthermore, the B-beam diffused by the diffuser plate 26, centered on the optical axis 2 which is the optical axis of the condenser lens 25, is transmitted through the condenser lens 25 and directed onto the dichroic mirror 24. At this time, the area of ​​the B-beam directed onto the dichroic mirror 24 is larger than the area of ​​the B-beam directed from the light source 21. Moreover, in the B-beam directed from the diffuser plate 26 onto the dichroic mirror 24, for example, when the area magnification of the B-beam incident region of the diffuser plate is 2, approximately 10% is reflected due to the shape of different characteristic regions, but approximately 90% is still transmitted.

[0048] On the other hand, the B-beam irradiated from the light source 21 onto the dichroic mirror 24, and the B-beam transmitted from the dichroic mirror 24, is focused by the condenser lens 27 and irradiated onto the phosphor wheel 28. The phosphor wheel 28 is coated with a phosphor that emits Y-beams using the B-beam as excitation light, and is rotated by the motor 29 to prevent burns. Then, Y-beams are emitted from the phosphor wheel 28 around the optical axis 1, transmitted through the condenser lens 27, and irradiated onto the dichroic mirror 24. The Y-beam is then reflected by the dichroic mirror 24, and overlaps with the B-beam to form a W-beam, which is a B+Y beam.

[0049] in addition, Figure 2B This is an example of the emission spectrum of the blue laser in this embodiment. Furthermore, Figure 2C This is an example of the emission spectrum of the yellow phosphor in this embodiment.

[0050] Thus, the light source device 2 of this embodiment generates white light W by using blue laser light from the light source 21 to synthesize B (cyan) + Y (yellow) light. That is, the light source device 2 can also be considered a white light generating unit. Furthermore, the dichroic mirror 24 is configured as a region with B transmission and Y reflection characteristics as a wide-area characteristic region, and includes a total internal reflection region in the central part of the dichroic mirror as a different characteristic region. Then, the B light is diffused by the diffuser plate 26, increasing the area of ​​the B light. As a result, the area of ​​the B light returning to the light source 21, which is not included in the white light W, is smaller, increasing the utilization rate of the B light.

[0051] Next, use Figure 4 This section describes an example of a coating method for the dichroic mirror 24 in this embodiment, which serves as a B-transmission and Y-reflection region as a wide-area characteristic region and a total reflection region as a different characteristic region, as well as an example of the transmittance characteristics of each region. Figure 4 (A) is a planar view, (B) is a cross-sectional view, (C) is the transmittance characteristics of the B-transmission and Y-reflection regions, and (D) is the transmittance characteristics of the total internal reflection region. Figure 4 As shown in (B), the dichroic mirror 24 can be manufactured by applying a dichroic coating with B-transmission and Y-reflection characteristics to one side of a glass substrate, applying an AR coating (Anti-Reflective Coating) to the opposite side, and then applying a mirror coating for the total reflection area on top of it. Furthermore, the transmittance characteristics of each region are as follows... Figure 4 As shown in (C), in the B-transmission and Y-reflection region, which is a wide-area characteristic region, the transmittance near 455 nm, the wavelength of B-light, is at least 95% or more, preferably as close as possible to 100%, and the transmittance of the green to red bands in the Y-light, which are around 500 to 700 nm, is at least 5% or less, preferably as close as possible to 0%. Furthermore, in the total internal reflection region, which is a different characteristic region, as... Figure 4 As shown in (D), the transmittance is at least 5% or less across the entire wavelength range, and preferably as low as possible, 0%.

[0052] Specifically, in various embodiments of the present invention, the B-light transmission and G-light reflection characteristics refer to the following: the transmittance near 455 nm, the wavelength of B-light, is at least 95%, and the reflectance of the green to red bands in the 500 to 700 nm range of G-light is at least 95%. Similarly, in various embodiments of the present invention, the B-light reflection and G-light transmission characteristics refer to the following: the reflectance near 455 nm, the wavelength of B-light, is at least 95%, and the transmittance of the green to red bands in the 500 to 700 nm range of G-light is at least 95%.

[0053] Furthermore, in various embodiments of the present invention, total transmittance means that the transmittance across the entire wavelength region, from approximately 455 nm in the blue band to 700 nm in the red band, is at least 95%. Similarly, in various embodiments of the present invention, total reflectance means that the reflectance across the entire wavelength region, from approximately 455 nm in the blue band to 700 nm in the red band, is at least 95%.

[0054] In addition, in the following explanation, when calculating light utilization rate, etc., in order to simplify the calculation, the characteristics of light reflecting in a specified area are calculated as 100% reflection, and the characteristics of light transmitting in a specified frequency band are calculated as 100% transmission.

[0055] Furthermore, in various embodiments of the present invention, in the "wide-area characteristic region," the transmission and reflection characteristics of B-ray and G-ray are configured in opposite ways. That is, when the "wide-area characteristic region" has the characteristic of B-ray transmission, the G-ray is configured to have the characteristic of reflection, resulting in the characteristic of the "wide-area characteristic region" being set to B-ray transmission and G-ray reflection. Conversely, when the "wide-area characteristic region" has the characteristic of B-ray reflection, the G-ray is configured to have the characteristic of transmission, resulting in the characteristic of the "wide-area characteristic region" being set to B-ray reflection and G-ray transmission.

[0056] Furthermore, in various embodiments of the present invention, in the "different characteristic regions," the transmission and reflection characteristics of B-ray and G-ray are configured identically. That is, when the "different characteristic region" has the characteristic of B-ray transmission, the G-ray is also configured to have transmission characteristics, resulting in the characteristics of the "different characteristic region" being set to total transmission characteristics. Moreover, when the "different characteristic region" has the characteristic of B-ray reflection, the G-ray is also configured to have reflection characteristics, resulting in the characteristics of the "different characteristic region" being set to total internal reflection characteristics.

[0057] Next, use Figure 3 This explains the principle behind the high efficiency of B-light utilization achieved using the structure of this embodiment. Figure 3In the examples, (A) is a case where the structure of this embodiment (region segmentation and diffuser plate with transmission and reflection characteristics) is not used, and (B) is an example of an optical system of a light source device having region segmentation and diffuser plate with transmission and reflection characteristics of this embodiment.

[0058] Figure 3 The transmission and reflection characteristics of the dichroic mirror 24 in structure (A) are consistent throughout the entire region, with the reflectance of B light being R1 and the transmittance of B light being T1. In this case, the ratio of the emitted B light (transmitted B light in this figure) to the incident B light, i.e., the B light utilization rate E1, is R1×(1-R1)=(R1×T1). For example, when the setting of 20% reflection and 80% transmission of the B light incident on the dichroic mirror 24 is adopted, i.e., R1=0.2 and T1=0.8, the B light utilization rate E1[%]=0.2×(1-0.2)×100=16[%].

[0059] On the other hand, in this embodiment Figure 3 In the case of structure (B), such as Figure 3 As shown in (C), let SI be the area of ​​the incident region I of the B incident light, SO be the area of ​​the incident region O of the B diffused light, SWI be the area of ​​the total internal reflection region WI (with a B light reflection characteristic R≈1) in the incident region I of the B incident light, and SWO be the area of ​​the total internal reflection region WO (with a B light reflection characteristic R≈1) in the incident region O of the B diffused light. Then, the actual reflectivity R2 of the B incident light at the dichroic mirror 24, as a proportion of the reflected B incident light from the laser source, can be calculated from SWI / SI. Furthermore, the actual transmittance T2 of the B diffused light at the dichroic mirror 24, as a proportion of the transmitted B diffused light, can be calculated from (SO-SWO) / SO. The B light utilization rate E2 is R2×T2=(SWI / SI)×((SO-SWO) / SO). Here, SWI / SI can also represent the utilization efficiency of the B light incident from the laser source to the dichroic mirror. In addition, (SO-SWO) / SO can also be expressed as the utilization efficiency of B light incident on the dichroic mirror from the diffused B light.

[0060] Here, for comparison Figure 3 (A) structure and Figure 3 The efficiency of structure (B) is considered by letting Figure 3 (A) B light reflectance R1 and Figure 3(B) The case where the actual reflectivity R2 of the incident light B is set to be equal. In this case, the condition for E2 > E1 is R2 × T2 > R1 × (1 - R1). Here, when R2 is substituted into R1, it becomes R2 × T2 > R2 × (1 - R2). When both sides are divided by R2, it becomes T2 > 1 - R2. It can be transformed into (SO - SWO) / SO > (SI - SWI) / SI. When both sides are multiplied by SO, it becomes SO - SWO > (SI - SWI) × SO / SI. When SO / SI is taken as the area magnification of the incident region of the diffused light as α, it becomes SO - SWO > SO - SWI × α, which can be transformed into SWI × α > SWO. It can be transformed into SWO / SWI < α, and if SWO / SWI = β, then α < β. This formula means that by setting the shape of the different characteristic regions of the dichroic mirror 24 such that the ratio β of the size of the different characteristic regions in the incident region O (which is the incident region of B diffused light) to the size of the different characteristic regions in the incident region I (which is the incident region of B incident light) is not greater than the area magnification α of the incident region of diffused light, the utilization rate of B light can be improved. Figure 3 (B) structure efficiency ratio Figure 3 (A) has a high structure efficiency. When the light utilization rate E2 of B is expressed using the formula α and β, it becomes E2 = R2 × T2 = R2 × (1 - (R2 × β / α)). That is, in this embodiment... Figure 3 In the structure of (B), if only the utilization rate of B light up to the emission of the dichroic mirror 24 is considered, the larger the area magnification α of the incident region of the diffused light, the higher the efficiency. The smaller the ratio β of SWO, which is the size of different characteristic regions in the incident region O of the B diffused light, to SWI, which is the size of different characteristic regions in the incident region I of the B incident light, the better.

[0061] Specifically, for example, when R2 = SWI / SI = 0.2, the area magnification of the incident region of diffused light α = SO / SI = 2, and the shape of different characteristic regions is β = SWO / SWI with a shape of 1.2, the utilization rate of B light E2[%] = 0.2 × (1 - (0.2 × 1.2 / 2)) × 100 = 17.2[%], which is greater.

[0062] It is greater than the case where R1 = 0.2. Figure 3 (A) has a light utilization rate of E1[%] = 16[%.

[0063] Thus, according to this embodiment, in the light source device that generates white light by using blue laser light to synthesize B+Y light in light source 21, it is possible to increase the utilization rate of B light by adopting a structure in dichroic mirror 24 that has a characteristic region of B transmission and Y reflection as a wide-area characteristic region and a total reflection region as a different characteristic region in the center, and by using diffuser plate 26 to diffuse B light, thereby expanding the area of ​​B light.

[0064] According to the embodiment described above, a projector that can more appropriately generate white light from a laser light source for image display can be realized.

[0065] Example 2

[0066] This embodiment is an example of changing the coating specifications of the dichroic mirror in the light source device of the projector in Embodiment 1, and accordingly changing the configuration of the phosphor wheel and the diffuser plate.

[0067] Furthermore, to simplify the explanation, this embodiment only describes the changes compared to Embodiment 1; structures and operations not specifically described are the same as in Embodiment 1. In particular, the structure and operation of the projector's optical system and image display element after generating white light W (B+Y light) in the light source device are the same as in Embodiment 1. Figure 1 Since they are the same, the explanation is omitted.

[0068] Figure 5 This is a structural diagram showing the light source device of the projector in this embodiment and a diagram showing the transmission and reflection characteristics of the dichroic mirror. Figure 5 In this drawing, structures with the same function as those in Figure 2 are labeled with the same reference numerals, and their descriptions are omitted. Figure 5 The difference between this and Figure 2 is that the transmission and reflection characteristics of the dichroic mirror are different, and the positions of the phosphor wheel and the diffuser plate are interchanged.

[0069] exist Figure 5In this process, a B-beam, which has become approximately parallel after passing through lens 23, is irradiated onto the dichroic mirror 91. Here, the dichroic mirror 91, as illustrated, has a characteristic region of B-beam reflection and Y-beam transmission as a wide-area characteristic region, and includes a fully transmissive region as a different characteristic region in the central part of the dichroic mirror. That is, the region of the dichroic mirror 91 with the characteristic of B-beam reflection and Y-beam transmission as a wide-area characteristic region is relatively wide, while some regions have fully transmissive characteristics (different characteristic regions) that are different from the characteristics of B-beam reflection and Y-beam transmission. For example, as an example, when the proportion of the fully transmissive region in the B-beam region irradiated from the light source 21 to the dichroic mirror is 20% of the total, the B-beam irradiated onto the dichroic mirror 91 is reflected by approximately 80% and transmitted by approximately 20%. That is, approximately 20% of the central part of the B-beam irradiated from the light source 21 to the dichroic mirror 91 is transmitted. The transmission and reflection characteristics of the dichroic mirror in Example 2 are different from those in Example 1, but the concepts are the same regarding the inclusion of a wide-area characteristic region with a defined transmission and reflection characteristic region and a different characteristic region that is partially different from the defined transmission and reflection characteristics in the same dichroic mirror.

[0070] The B beam reflected by the dichroic mirror 91 is focused by the condenser lens 27 and irradiates the phosphor wheel 28. Centered on the optical axis 2, which serves as the optical axis of the condenser lens 27, the Y beam is emitted from the phosphor wheel 28, transmitted through the condenser lens 27, and irradiates the dichroic mirror 91. The Y beam is transmitted through the dichroic mirror 91.

[0071] On the other hand, the B-beam irradiated from the light source 21 to the dichroic mirror 91, after being transmitted through the dichroic mirror 91, is focused by the condenser lens 25 and irradiated onto the diffuser plate 26. Centered on the optical axis 1, the B-beam diffused by the diffuser plate 26 is transmitted through the condenser lens 25 and irradiates the dichroic mirror 91. At this time, the area of ​​the B-beam irradiated onto the dichroic mirror 91 is larger than the area of ​​the B-beam irradiated from the light source 21 to the dichroic mirror 91. For example, when the area magnification of the B-beam incident region of the diffuser plate is 2, approximately 10% is transmitted due to the different shapes of the regions, but approximately 90% is still reflected. Furthermore, the B-beam reflected by the dichroic mirror 91 overlaps with the Y-beam, becoming a B+Y beam. Therefore, according to the structure of Embodiment 2, the utilization rate of B-beam can be increased to the same extent as in Embodiment 1.

[0072] Figure 6 This diagram illustrates the coating method for the B-reflection and Y-transmission regions and the total transmission region of the dichroic mirror 91 in this embodiment, as well as the transmittance characteristics of each region. Figure 6 (A) is a planar view, (B) is a cross-sectional view, (C) is the transmittance characteristics of the B reflection and Y transmission regions, and (D) is the transmittance characteristics of the total transmission region. For example... Figure 6As shown in (B), the dichroic mirror 91 can be manufactured by applying an AR coating to one side of a glass substrate, and applying a dichroic coating with B-reflection and Y-transmission characteristics and an AR coating for the full transmission region to the opposite side. Furthermore, the transmittance characteristics of each region are as follows: Figure 6 As shown in (C), in the B-reflection and Y-transmission region, which is a wide-area characteristic region, the transmittance near 455 nm, the wavelength of B-light, is at least 5% or less, preferably as close as possible to 0%, and the transmittance of the green to red bands in the Y-light, around 500 to 700 nm, is at least 95% or more, preferably as close as possible to 100%. Furthermore, in the total internal reflection region, which is a different characteristic region, as... Figure 6 As shown in (D), the transmittance is at least 95% or more across the entire wavelength range, preferably as high as 100%.

[0073] Furthermore, details regarding the principles and conditions for maximizing B-light utilization in the structure of this embodiment can be found in Embodiment 1. Figure 3 In the explanation, simply replace "transmission" with "reflection" for B-rays and "total internal reflection" with "total transmission." Specifically, let... Figure 3 (C) The area of ​​the incident region I of the incident B light is SI, the area of ​​the incident region O of the diffuse B light is SO, the area of ​​the total transmission region WI (transmission characteristic T≈1 of B light) in the incident region I of the incident B light as a region with different characteristics is SWI, and the area of ​​the total transmission region WO (transmission characteristic T≈1 of B light) in the incident region O of the diffuse B light as a region with different characteristics is SWO. At this time, the actual transmittance T3 of the incident B light at the dichroic mirror 91, which is the proportion of the transmitted light of the incident B light from the laser source, can be calculated from SWI / SI. In addition, the actual reflectance R3 of the diffuse B light at the dichroic mirror 91, which is the proportion of the transmitted light of the diffuse B light, can be calculated from (SO-SWO) / SO. The B light utilization rate E3 of the light source device of Example 2 is T3×R3=(SWI / SI)×((SO-SWO) / SO). That is, even if the reflection and transmission characteristics of B light are opposite to those in Example 1, the B light utilization rate E3 of the light source device remains unchanged, and is still the product of the utilization efficiency (SWI / SI) of B light incident from the laser source to the dichroic mirror and the utilization efficiency ((SO-SWO) / SO) of B light incident from the diffused B light to the dichroic mirror.

[0074] Thus, the B-light utilization rate E3 of the light source device in this embodiment is also the same as the variation of E2 in embodiment 1. By using the area magnification α of the incident region of diffused light and the ratio β of the size of the different characteristic regions in the incident region O of B diffused light to the size of the different characteristic regions in the incident region I of B incident light, SO / SI can be expressed as E3=T3×R3=T3×(1-(T3×β / α)).

[0075] That is, in the structure of this embodiment, the following situation also applies: if only the utilization rate of B light up to the emission of the dichroic mirror 91 is considered, the larger the area magnification α of the incident region of the diffused light, the higher the efficiency, and the smaller the ratio β of SWO, which is the size of different characteristic regions in the incident region O of the B diffused light, to SWI, which is the size of different characteristic regions in the incident region I of the B incident light, the better.

[0076] Thus, according to this embodiment, in the light source device that generates white light by using blue laser light to synthesize B+Y light in light source 21, it is possible to increase the utilization rate of B light by adopting a structure in the dichroic mirror 91 that has a characteristic region of B reflection and Y transmission as a wide-area characteristic region and a full transmission region as a different characteristic region in the center, and by using the diffuser plate 26 to diffuse the B light and amplify the area of ​​the B light.

[0077] According to the above-described embodiment, in a different structure than Embodiment 1, a projector that can more appropriately generate white light from a laser light source for image display can also be realized to the same extent as Embodiment 1.

[0078] Example 3

[0079] This embodiment illustrates an example in which different characteristic regions of the dichroic mirror of the light source device are arranged in the projector of Embodiment 1 at a position away from the central part where the optical axis 2, which is the optical axis of the condenser lens 25, intersects with the dichroic mirror.

[0080] Figure 7 This is a structural diagram showing the light source device of this embodiment and a diagram showing the transmission and reflection characteristics of the dichroic mirror. Figure 7 In the figures, structures with the same function as those in Figure 2 are labeled with the same reference numerals, and their descriptions are omitted.

[0081] In Figure 2 of Embodiment 1, the different characteristic regions of the dichroic mirror are positioned near the center where the optical axis 2 intersects with the dichroic mirror. In contrast, in this embodiment… Figure 7 In this context, the positions of different characteristic regions are defined as those located away from the central part where the optical axis 2 intersects with the dichroic mirror.

[0082] To change the positions of different characteristic regions away from the central portion where the optical axis 2 intersects with the dichroic mirror, these regions can be positioned away from the central portion only within the range of the incident B-color laser light from the B-color laser source 21. Furthermore, by positioning the optical axis 1 of the B-color laser source 21 away from the optical axis 3, which is in a mirror-like arrangement relative to the optical axis 2 of the condenser lens 25, the different characteristic regions can be further positioned away from the optical axis 2. Figure 7In the example shown, the departure of the optical axis 1 of the laser light source 21 and the departure from the central part of the different characteristic regions are both examples.

[0083] exist Figure 7 In the process, the B-beam, which becomes parallel through lens 23, illuminates the dichroic mirror 92. Here, the dichroic mirror 92, as shown, has a characteristic region of B-beam transmission and Y-beam reflection as a wide-area characteristic region, and a total internal reflection region, which is a different characteristic region, is set at a position away from the position intersecting with the optical axis 2. For example, when the proportion of the total internal reflection region in the B-beam region illuminating the dichroic mirror from the light source 21 is set to 20% of the total, the B-beam illuminating the dichroic mirror 92 is reflected by approximately 20% and transmitted by approximately 80%. That is, 20% of the portion of the B-beam illuminating the dichroic mirror 92 from the center of the B-beam is reflected.

[0084] The B-beam reflected by the dichroic mirror 92 is diffused by the diffuser plate 26 and shines onto the dichroic mirror 92. At this time, the area of ​​the B-beam shining onto the dichroic mirror 92 is larger than the area of ​​the B-beam shining from the light source 21 onto the dichroic mirror 92.

[0085] Next, the proportion of the B-beam irradiated from the diffuser 26 to the dichroic mirror 92 that is reflected in different characteristic regions and transmitted in a wide-area characteristic region is calculated solely based on the area ratio. For example, when the area expansion rate of the B-beam incident region using the diffuser is 2 based on the area ratio, it is assumed, as an example, that approximately 10% is reflected and approximately 90% is transmitted due to the shape of the different characteristic regions. Here, unlike Example 1, in Example 3, the positions of the different characteristic regions are moved away from the central portion where the optical axis 2 intersects with the dichroic mirror. Figure 8 This diagram shows the illuminance distribution of light emitted from diffuser plate 26. (Example) Figure 8 As shown, the further away from the center position, the lower the illuminance. Thus, by arranging the positions of the different characteristic regions away from the center where the optical axis 2 intersects with the dichroic mirror, as in Embodiment 3, for example, even if the areas of the different characteristic regions are the same as in Embodiment 1, the portion of the B-diffuse light from the diffuser plate 26 that is reflected back to the light source 21 by the dichroic mirror 92 is not... Figure 8 The peak intensity at the center angle is smaller than the relatively smaller intensity at the peripheral angles, which, compared to Figure 2 of Embodiment 1, reduces the amount of reflected light directed towards the laser source. For example, in the structure described below, when this bias is used... Figure 8 When the relative effect of diffused light intensity is 50%, the area magnification of the B-beam incident region of the diffuser plate is 2. Considering only the area ratio, in a structure where approximately 10% is reflected and approximately 90% is transmitted due to the different shapes of the regions, the actual B-beam irradiated from the diffuser plate 26 to the dichroic mirror 92 is taken into account. Figure 8The intensity distribution shows that about 5% is reflected and about 95% is transmitted.

[0086] On the other hand, the B-beam illuminating the dichroic mirror 92 from the light source 21, and the B-beam transmitted through the dichroic mirror 92, illuminates the phosphor wheel 28. Furthermore, with the optical axis 3, which serves as the optical axis of the condenser lens 27, as the center, Y-beams are emitted from the phosphor wheel 28 and illuminate the dichroic mirror 92. Moreover, the Y-beams are reflected by the wide-area characteristic region of the dichroic mirror 92, overlapping with the B-beams to form a B+Y beam.

[0087] Figure 9 This diagram illustrates the coating method for the B-transmission and Y-reflection regions, which are the wide-area characteristic regions of the dichroic mirror 92 in this embodiment, and the total reflection regions, which are different characteristic regions. Figure 9 (A) is a plan view, and (B) is a cross-sectional view. For example... Figure 9 As shown in (B), the dichroic mirror 92 can be manufactured by applying a dichroic coating with B transmission and Y reflection characteristics on one side of a glass substrate, applying an AR coating on the opposite side, and applying a mirror coating for the total reflection area thereon.

[0088] According to the above-described embodiment, in the light source device that generates white light by synthesizing B+Y light using blue laser light from light source 21, it is possible to increase the utilization rate of B light by employing a dichroic mirror 92 with a characteristic region having B transmission and Y reflection as a wide-area characteristic region, and by arranging the total reflection region, which is a different characteristic region, away from the position where the optical axis 2, which is the optical axis of the condenser lens 25, intersects. The transmission and reflection characteristics are divided into regions, and the B light is diffused by the diffuser plate 26, thereby increasing the area of ​​B light.

[0089] As explained above, according to this embodiment, compared with Embodiment 1, the utilization rate of B light can be increased, and a projector that can more appropriately generate white light from a laser light source for image display can be realized.

[0090] Example 4

[0091] This embodiment illustrates an example in the projector of Embodiment 2, in which different characteristic regions of the dichroic mirror of the light source device are arranged at a position away from the central part where the optical axis 3, which is the optical axis of the condenser lens 25, intersects with the dichroic mirror.

[0092] Figure 10 This is a structural diagram showing the light source device of this embodiment and a diagram showing the transmission and reflection characteristics of the dichroic mirror. Figure 10 In the middle, for those with Figure 5 Structures with the same function are labeled with the same reference numerals in the accompanying drawings, and their descriptions are omitted.

[0093] In Example 2 Figure 5The different characteristic regions of the dichroic mirror are positioned near the center where the optical axis 3 intersects with the dichroic mirror. In contrast, in this embodiment... Figure 10 In this context, the positions of different characteristic regions are defined as those that depart from the central part where the optical axis 3 intersects with the dichroic mirror.

[0094] To change the positions of different characteristic regions so that they are located away from the central portion where the optical axis 2 intersects with the dichroic mirror, the different characteristic regions can also be positioned away from the central portion where the optical axis 3 intersects with the dichroic mirror, only within the range of the incident B-color laser light from the B-color laser source 21. Furthermore, by arranging the optical axis 1 of the B-color laser source 21 away from the optical axis 3, the different characteristic regions can be further arranged away from the optical axis 3. Figure 10 In the example shown, the departure of the optical axis 1 of the laser light source 21 and the departure of different characteristic regions from the central part are both examples.

[0095] exist Figure 10 In the process, a B-beam, parallelized by lens 23, is irradiated onto the dichroic mirror 93. Here, the dichroic mirror 93, as shown, has a region exhibiting both B-beam reflection and Y-beam transmission characteristics over a wide area, and a region exhibiting total transmission characteristics at a position away from the point intersecting with the optical axis 3, representing a different characteristic region. For example, when the proportion of the total transmission region representing a different characteristic region in the B-beam region irradiated from the light source 21 to the dichroic mirror is 20% of the total, the B-beam irradiated by the dichroic mirror 93 is reflected by approximately 80% and transmitted by approximately 20%. That is, approximately 20% of the portion of the B-beam irradiated from the light source 21 to the dichroic mirror 93 that is away from the center of the B-beam is transmitted.

[0096] The B beam, reflected by the dichroic mirror 93, illuminates the phosphor wheel 28. Centered on the optical axis 2, which serves as the optical axis of the condenser lens 27, the Y beam is emitted from the phosphor wheel 28 and illuminates the dichroic mirror 93, and is transmitted through the dichroic mirror 93.

[0097] On the other hand, among the B-beams illuminating the dichroic mirror 93 from the light source 21, the B-beams transmitted through the dichroic mirror 93 illuminate the diffuser plate 26. Centered on the optical axis 3, which serves as the optical axis of the condenser lens 25, the B-beams diffused by the diffuser plate 26 illuminate the dichroic mirror 93. At this time, the area of ​​the B-beam illuminating the dichroic mirror 93 is larger than the area of ​​the B-beam illuminating the dichroic mirror 93 from the light source 21.

[0098] Next, in the B-beam irradiated from the diffuser 26 to the dichroic mirror 93, the proportion transmitted in different characteristic regions and the proportion reflected in the wide-area characteristic regions are calculated solely based on the area ratio. For example, considering a structure where approximately 10% is transmitted and approximately 90% is reflected due to the shape of different characteristic regions, with an area magnification of 2 for the B-beam incident region using the diffuser 26, this is taken as an example. Here, unlike in Embodiment 2, in this embodiment, the positions of the different characteristic regions are located away from the central portion where the optical axis 3 intersects with the dichroic mirror. Here, as... Figure 8 As shown, the further the illuminance distribution of the light emitted from the diffuser plate 26 is offset from the center position, the lower the illuminance. Thus, by arranging the positions of the different characteristic regions away from the center where the optical axis 3 intersects with the dichroic mirror, as in Embodiment 3, for example, even if the areas of the different characteristic regions are the same as in Embodiment 2, the portion of the B-diffuse light from the diffuser plate 26 that is transmitted through the dichroic mirror 93 and returns to the light source 21 is not... Figure 8 The peak intensity at the center angle becomes a relatively small intensity at the peripheral angle, compared to Example 2. Figure 5 This reduces the amount of light returning to the laser source. For example, in the structure described below, when this bias is used... Figure 8 When the relative effect of diffused light intensity is 50%, the area expansion rate of the B-beam incident region using the diffuser plate is 2. Considering only the area ratio, in a structure where approximately 10% is transmitted and approximately 90% is reflected due to the different shapes of the regions, the actual B-beam irradiated from the diffuser plate 26 to the dichroic mirror 93 is taken into account. Figure 8 The intensity distribution shows that about 5% is reflected and about 95% is transmitted.

[0099] Moreover, the B beam reflected by the wide-area characteristic region of the dichroic mirror 93 overlaps with the Y beam, becoming a B+Y beam.

[0100] Figure 11 This diagram illustrates the coating method for the B-reflection and Y-transmission regions, which are the wide-area characteristic regions of the dichroic mirror 93 in this embodiment, and the full-transmission regions, which are different characteristic regions. Figure 11 (A) is a plan view, and (B) is a cross-sectional view. For example... Figure 11 As shown in (B), the dichroic mirror 93 is manufactured by applying an AR coating on one side of a glass substrate, applying a dichroic coating with B reflection and Y transmission characteristics on the opposite side, and applying an AR coating for the full transmission area.

[0101] According to the above-described embodiment, in the light source device that generates white light by synthesizing B+Y light using blue laser light from light source 21, it is possible to increase the utilization rate of B light by adopting a structure in which the transmission and reflection characteristics are divided into regions by using a dichroic mirror 93 with a characteristic region of B reflection and Y transmission as a wide-area characteristic region and arranging the fully transmissive region as a different characteristic region away from the position where the optical axis 3 of the condenser lens 25 intersects. The diffusion plate 26 is used to diffuse the B light, thereby increasing the area of ​​B light.

[0102] As explained above, according to this embodiment, compared with Embodiment 2, the utilization rate of B light can be increased, and a projector that can more appropriately generate white light from a laser light source for image display can be realized.

[0103] Example 5

[0104] This embodiment illustrates an example of using a segmented structure of the transmission and reflection region of a dichroic mirror and multiple lasers as light sources in a projector described in Embodiments 1 to 4, and achieving dimming and / or color adjustment by changing the intensity of the lasers.

[0105] Figure 12 This is a schematic structural diagram of the light source section of the light source device in this embodiment. Figure 12 express Figure 2A , Figure 5 , Figure 7 or Figure 10 The structure of the light source device is detailed below. Specifically, two light sources 21-1 and 21-2 are used as the light source 21, which are driven by power supply 1 (20-1) and power supply 2 (20-2), and a control unit 10 for controlling the power supply 1 and power supply 2 is provided.

[0106] Figure 13 This indicates that it is similar to Example 1 ( Figure 2A The diagram shows the segmentation structure of the transmission and reflection regions of a dichroic mirror (the structure of which is shown) and its variants. Figure 13 (A) is the structure corresponding to Example 1. Figure 13 In (A), the regions spanning the B-transmission Y-reflection region (wide-area characteristic region M) and the total reflection region (different characteristic region W) have irradiation regions E21-1 and E21-2 respectively irradiated by B-light from light source 21-1 and B-light from light source 21-2. Furthermore, the region formed by merging the irradiation regions E21-1 and E21-2 is equivalent to... Figure 3 Region I of (C). Additionally... Figure 13 (A) shows the incident region of diffused light B, which is equivalent to... Figure 3 (C) region O.

[0107] exist Figure 13 In example (A), the regions are arranged symmetrically, and the ratio of the wide-area characteristic region M to the different characteristic region W within the illumination region E21-1 is the same as the ratio of the wide-area characteristic region M to the different characteristic region W within the illumination region E21-2. Therefore, it is possible to achieve a dimming function that directly adjusts the intensity of the light output from the light source device 2 without changing the ratio of B-light to Y-light output from the light source device 2 simply by changing the intensity of the laser light from light sources 21-1 and 21-2.

[0108] Figure 13 (B) is Figure 13 A variation of region segmentation in (A), and Figure 13 (A) Different, the total internal reflection region W, which is a region with different characteristics, is wider in the width direction of the paper and is included in the region formed by merging the irradiation region E21-1 of the light B emitted from light source 21-1 and the irradiation region E21-2 of the light B emitted from light source 21-2 (equivalent to...). Figure 3 In region I of (C). Figure 13 In example (B), since the different characteristic regions W are contained within region I, the different characteristic regions W are equivalent to Figure 3 (C) refers to both regions WI and WO in the example. As explained in Embodiment 1, in the light source device 2, the smaller the ratio β of the size of the different characteristic regions SWO in the incident region O as the diffused B light to the size of the different characteristic regions SWI in the incident region I as the incident B light, the higher the utilization efficiency of the B light as the light source device. Here, by including the different characteristic regions W in region I, β can be set to 1, and β can be minimized.

[0109] Additionally, as described in Example 1 Figure 3 (B) structure's B-light utilization efficiency E2 is always better than [the previous one] when β / α is less than 1. Figure 3 (A) has a light utilization efficiency E1 of B. Thus, as long as β = 1 is made by including different characteristic regions W within region I, α will be greater than 1 due to the effects of the condenser lens 25 and the diffuser plate 26. Figure 3 (B) structure and Figure 3 The structure of (A) must have a higher light utilization efficiency than that of B.

[0110] Thus, adopt Figure 13 (B) A structure that includes different characteristic regions W within region I, and Figure 13 (A) Compared to structures where different characteristic regions W are not included in region I, the utilization rate of light B can be improved.

[0111] In addition, Figure 13In the structure of (A), since the different characteristic regions W exist in a long and thin shape at the longitudinal boundaries of the irradiation regions E21-1 and E21-2, the ratio of the wide-area characteristic region M to the different characteristic regions W in the irradiation region E21-1 and the ratio of the wide-area characteristic region M to the different characteristic regions W in the irradiation region E21-2 will change significantly depending on the assembly precision of the optical components. For example, due to the aforementioned shift in relative position, if the B light irradiated into the total internal reflection region of the different characteristic region W becomes only one of the left and right light sources, and the power supply controlling this one laser light source fails, only the light that has passed through the wide-area characteristic region M from the light source incident on the dichroic mirror will be used. Therefore, only either B light or Y light will be output from the light source device 2 (in Figure 13 In example (A), the light source is Y-ray, which cannot produce white light. Conversely, if... Figure 13 With structure (B), since the total reflection region W, which is a different characteristic region, is wide in the width direction, even if the relative position shift in the left and right directions is generated as described above, the B light irradiated onto the total reflection region W, which is a different characteristic region, is not likely to become only one of the left and right light sources.

[0112] Therefore, in Figure 13 In the structure of (B), even if the power supply controlling a laser light source fails, it is possible to avoid the phenomenon that the light output from the light source device 2 becomes either B light or Y light.

[0113] also, Figure 13 (C) is yet another variation of a different region segmentation. Figure 13 In example (C), with Figure 13 (A) Figure 13Unlike example (B), the total internal reflection regions, which are different characteristic regions W, are constructed in an asymmetrical manner. This results in different ratios between the wide-area characteristic region M and the different characteristic regions W within the illumination region E21-1 and between the wide-area characteristic region M and the different characteristic regions W within the illumination region E21-2. Consequently, the ratio of B-light to Y-light that ultimately contributes to the output light of the light source device 2 from the B-light from light source 21-1 and the ratio of B-light to Y-light that ultimately contributes to the output light of the light source device 2 from the B-light from light source 21-2 are different. Thus, by variably controlling the light intensity of light source 21-1 via power supply 1, or variably controlling the light intensity of light source 21-2 via power supply 2, the relative ratio of the light intensities of light source 21-1 and light source 21-2 can be varied, thereby enabling control over both the color and intensity of the light output from the light source device 2. That is, color adjustment and dimming functions of the light output from the light source device 2 can be achieved.

[0114] In addition, Figure 13 In example (C), since the different characteristic region W is contained in the region (region I) formed by merging the irradiation region E21-1 and the irradiation region E21-2, it also has the advantage of high light utilization of B.

[0115] also, Figure 13 (D) is yet another variation of a different region segmentation. Figure 13 In example (D), with Figure 13 Similar to example (C), the ratio of the wide-area characteristic region M to the different characteristic regions W within the irradiation area E21-1 is different from the ratio of the wide-area characteristic region M to the different characteristic regions W within the irradiation area E21-2. Therefore, with... Figure 13 Similar to example (C), by controlling the light intensity of light source 21-1 via power supply 1, or by controlling the light intensity of light source 21-2 via power supply 2, the relative ratio of the light intensity of light source 21-1 to the light intensity of light source 21-2 can be changed, thereby enabling control of both the color and intensity of the light output by light source device 2.

[0116] Furthermore, in Figure 13In example (D), the different characteristic regions W (total internal reflection regions) each have an independent shape for the illumination area from each of the left and right light sources. Furthermore, different characteristic regions W are respectively positioned at a distance from the boundary lines of the illumination areas from the left and right light sources. Therefore, depending on the assembly precision of the optical components, the relative positions of the illumination area E21-1, the illumination area E21-2, and the different characteristic regions W of the dichroic mirror, whether shifted in the left-right direction or the up-down direction, can be designed to maintain a structure where the ratio of the wide-area characteristic region M to the different characteristic regions W within the illumination area E21-1 and the ratio of the wide-area characteristic region M to the different characteristic regions W within the illumination area E21-2 remains relatively constant.

[0117] That is, in Figure 13 In example (D), the preferred approach is to simultaneously realize the color adjustment function and the dimming function of the light output from the light source device 2, and to reduce the influence of the relative position shift of the irradiation area E21-1, the irradiation area E21-2, and the different characteristic areas W of the dichroic mirror based on the assembly accuracy of optical components.

[0118] In addition, Figure 13 In example (D), since the different characteristic regions W are contained in the region (region I) formed by merging the irradiation regions E21-1 and E21-2, it also has the advantage of high utilization of B light.

[0119] As mentioned above, using Figure 13 Several embodiments 1 are described. Figure 2A Examples of the shapes of different characteristic regions W of the structure and their variations. Furthermore, these variations can also be applied to, as in Example 3. Figure 7 In this case, the optical axis 1 of the light source 21 is biased relative to the optical axis 3 which is in mirror relationship with the optical axis 2 of the condenser lens 25.

[0120] also, Figure 14 This is a diagram showing the segmentation structure of the transmission and reflection regions of the dichroic mirror corresponding to Example 2 and its variations. Figure 14 (A) is the structure corresponding to Example 2. Figure 14 (A) describes Example 2. Figure 5 In the structure, 21 is used as the light source. Figure 12 The diagram shows an example of the structure shown. Figure 14 (B)(C)(D) are variations of this.

[0121] Here, Figure 14 (A) Figure 14 (B) Figure 14 (C) Figure 14The example of the segmented structure of the transmission and reflection regions of the dichroic mirror described in (D) is to make... Figure 13 (A) Figure 13 (B) Figure 13 (C) Figure 13 (D) The segmentation structure of the transmission and reflection regions of the dichroic mirror is as described in Example 2, where the characteristics of the wide-area characteristic region M are transformed into B-reflection and Y-transmission, and the characteristics of the different characteristic regions W are transformed into a fully transmissive structure. If... Figure 13 If the description is replaced accordingly with the change in this characteristic, then the structure and its effects also become... Figure 14 Explanation of each figure. Therefore, Figure 14 The descriptions of each figure are as follows: Figure 13 The process of replacing each diagram is recorded, but further records are omitted.

[0122] Based on the above explanation Figure 14 The figures illustrate examples of the segmented structure of the transmission and reflection regions of a dichroic mirror, demonstrating examples of the shapes of different characteristic regions W in various embodiments 2, and their variations. Furthermore, these variations can also be applied to embodiments such as embodiment 4. Figure 10 In this case, the optical axis 1 of the light source 21 is biased relative to the optical axis 3 which is in mirror relationship with the optical axis 2 of the condenser lens 25.

[0123] Based on the above-described example of the segmentation structure of the transmission and reflection region of the dichroic mirror, any effect or combination of effects can be obtained, such as improved B light utilization, realization of dimming function, realization of color adjustment function, and reduction of the influence of relative position offset based on the assembly accuracy of optical components, in accordance with the shape of different characteristic regions W and the relationship between the illumination regions of multiple light sources on the dichroic mirror.

[0124] In addition, in this embodiment Figure 13 , Figure 14 The descriptions of the figures illustrate an example where the irradiation areas E21-1 and E21-2 do not overlap. However, the irradiation areas E21-1 and E21-2 may also partially overlap, which is also a variation of this embodiment. In this case, as long as the ratio of the wide-area characteristic region M to the different characteristic regions W within each irradiation area satisfies the above description, the same effect as described above can be obtained.

[0125] Example 6

[0126] In Example 5, two lasers were used as the light source for the projector. In contrast, this example describes the case where three lasers are used as the light source for the projector.

[0127] Figure 15 This is a schematic structural diagram of the light source section of the light source device in this embodiment. Figure 15In Figure 2A , Figure 5 , Figure 7 or Figure 10 The structure of the light source device uses three light sources 21-1, 21-2, and 21-3, which are driven by power supply 1 (20-1), power supply 2 (20-2), and power supply 3 (20-3), and has a control unit 11 for controlling each power supply 1, power supply 2, and power supply 3.

[0128] Figure 16 This indicates that it is similar to Example 1 ( Figure 2A The diagram shows the segmentation structure of the transmission and reflection regions of a dichroic mirror (the structure of which is shown) and its variants. Figure 16 (A) is the structure corresponding to Example 1. Figure 16 In (A), there is an illumination area E21-1 in the B-transmission Y-reflection region (wide-area characteristic region M) on the left, which is illuminated by B light from light source 21-1; there is an illumination area E21-2 in the region spanning the B-transmission Y-reflection region (wide-area characteristic region M) on the left, the total reflection region (different characteristic region W) and the B-transmission Y-reflection region (wide-area characteristic region M) on the right, which is illuminated by B light from light source 21-2; and there is an illumination area E21-3 in the B-transmission Y-reflection region (wide-area characteristic region M) on the right, which is illuminated by B light from light source 21-3. Because the ratio of the wide-area characteristic region M to the different characteristic regions W in the irradiation area E21-2 is different from the ratio of the wide-area characteristic region M to the different characteristic regions W in the irradiation areas E21-1 and E21-3 (the different characteristic regions W are 0% in this figure), the ratio of B light to Y light output from the light source device 2 can be changed by changing the intensity of the lasers from light sources 21-1, 21-2, and 21-3, thereby realizing the color adjustment and dimming functions.

[0129] Figure 16 (B) is Figure 16 A variation of region segmentation in (A), and Figure 16 (A) Different, the total internal reflection region W, which has different characteristics, is wider in the width direction of the paper and is included in the region formed by merging the irradiated region E21-1 of the light source 21-1, the irradiated region E21-2 of the light source 21-2, and the irradiated region E21-3 of the light source 21-3 (equivalent to...). Figure 3 In region I) of (C). Based on this structure, it is possible to... Figure 13 As explained in (B), let β = 1 in the B-light utilization efficiency. This will improve the B-light utilization efficiency.

[0130] In addition, Figure 16In structure (A), if power supply 20-2 fails, only the light incident from the light source to the dichroic mirror that has passed through the wide-area characteristic region M is utilized. Therefore, only Y light is output from the light source device 2, making it impossible to reproduce white light. In contrast, if... Figure 16 The structure of (B) means that the total reflection regions of different characteristic regions W respectively involve all regions of the irradiation regions E21-1, E21-2, and E21-3.

[0131] Therefore, in Figure 16 In the structure of (B), even if one of the multiple power supplies controlling the laser light source fails, it is possible to avoid the phenomenon that the light output from the light source device 2 becomes either B light or Y light.

[0132] also, Figure 16 (C) is another variation of region segmentation. Figure 13 In (C), the illumination area of ​​multiple laser sources is 2. In contrast, in Figure 16 In structure (C), three irradiation regions are added: E21-1, E21-2, and E21-3. Furthermore, the ratios of the wide-area characteristic region M to the different characteristic regions W in these three irradiation regions are all changed.

[0133] Thus, by variably controlling the light intensity of light source 21-1, light source 21-2, and light source 21-3, both the color and intensity of the light output from light source device 2 can be controlled. Furthermore, with... Figure 13 (C) Compared to the number of region segments, it has more, thus enabling improved decomposition of color and intensity control.

[0134] also, Figure 16 (D) is yet another variation of region segmentation. Figure 16 In example (D), with Figure 16 Similar to example (C), the ratio of the wide-area characteristic region M to the different characteristic regions W within the irradiation area E21-1, the ratio of the wide-area characteristic region M to the different characteristic regions W within the irradiation area E21-2, and the ratio of the wide-area characteristic region M to the different characteristic regions W within the irradiation area E21-3 are different. Therefore, it is possible to... Figure 16 Similar to example (C), both the color and intensity of the light output from the light source device 2 can be controlled by variably controlling the light intensity of light source 21-1, light source 21-2, and light source 21-3. Furthermore, with... Figure 13 (D) Compared to the number of region segments, it has more, thus enabling improved decomposition of color and intensity control.

[0135] Furthermore, in Figure 16In example (D), each illumination region from the three light sources has an independent shape, representing a different characteristic region W (total internal reflection region). Furthermore, different characteristic regions W are positioned at distances from the boundaries of each illumination region. Therefore, depending on the assembly precision of the optical components, the relative positions of illumination regions E21-1, E21-2, and E21-3, and the different characteristic regions W of the dichroic mirror, regardless of whether they are offset laterally or vertically, can maintain a structure where the ratio of the wide-area characteristic region M to the different characteristic regions W within illumination region E21-1, E21-2, and E21-3 remains relatively constant.

[0136] That is, in Figure 16 In example (D), the preferred approach is to simultaneously realize the color adjustment function and the dimming function of the light output from the light source device 2, and to reduce the influence of the relative position shift of the irradiation area E21-1, the irradiation area E21-2, the irradiation area E21-3, and the different characteristic areas W of the dichroic mirror, based on the assembly accuracy of optical components, etc.

[0137] In addition, Figure 16 In example (D), since the different characteristic regions W are contained in the region (region I) formed by merging the irradiation regions E21-1, E21-2 and E21-3, it also has the advantage of high utilization of B light.

[0138] As mentioned above, using Figure 16 This describes several embodiments 1 ( Figure 2A Examples of the shapes of different characteristic regions W of the structure and their variations. Furthermore, these variations can also be applied to, as in Example 3. Figure 7 In this case, the optical axis 1 of the light source 21 is biased relative to the optical axis 3 which is in mirror relationship with the optical axis 2 of the condenser lens 25.

[0139] also, Figure 17 This is a diagram showing the segmentation structure of the transmission and reflection regions of the dichroic mirror corresponding to Example 2 and its variations. Figure 17 (A) is the structure corresponding to Example 2. Figure 17 (A) describes Example 2. Figure 5 In the structure, 21 is used as the light source. Figure 15 The diagram shows an example of the structure shown. Figure 17 (B)(C)(D) are variations of this.

[0140] Here, Figure 17 (A) Figure 17 (B) Figure 17 (C) Figure 17 The example of the segmented structure of the transmission and reflection regions of the dichroic mirror described in (D) is to make... Figure 16 (A) Figure 16 (B) Figure 16 (C) Figure 16 (D) The segmentation structure of the transmission and reflection regions of the dichroic mirror is as described in Example 2, where the characteristics of the wide-area characteristic region M are transformed into B-reflection and Y-transmission, and the characteristics of the different characteristic regions W are transformed into a fully transmissive structure. If... Figure 16 If the description is replaced accordingly with the change in this characteristic, then the structure and its effects also become... Figure 17 Explanation of each figure. Therefore, Figure 17 The descriptions of each figure are as follows: Figure 16 The process of replacing each diagram is recorded, but further records are omitted.

[0141] Based on the above explanation Figure 17 The figures illustrate examples of the segmented structure of the transmission and reflection regions of a dichroic mirror, demonstrating examples of the shapes of different characteristic regions W in various embodiments 2, and their variations. Furthermore, these variations can also be applied to embodiments such as embodiment 4. Figure 10 In this case, the optical axis 1 of the light source 21 is biased relative to the optical axis 3 which is in mirror relationship with the optical axis 2 of the condenser lens 25.

[0142] Based on the above-described example of the segmented structure of the transmission and reflection regions of the dichroic mirror in this embodiment, any effect or combination of effects can be obtained, such as improved B-light utilization, realization of dimming function, realization of color adjustment function, and reduction of the influence of relative positional offset based on the assembly accuracy of optical components, corresponding to the shape of different characteristic regions W and the relationship between the illumination regions of multiple light sources on the dichroic mirror. Furthermore, the resolution can be further improved in the dimming and color adjustment functions.

[0143] In addition, in this embodiment Figure 16 , Figure 17 The descriptions of the figures illustrate an example where irradiation regions E21-1, E21-2, and E21-3 do not overlap. However, irradiation regions E21-1, E21-2, and E21-3 may also partially overlap, which is also a variation of this embodiment. In this case, as long as the ratio of the wide-area characteristic region M to the different characteristic regions W within each irradiation region satisfies the above description, the same effect as described above can be obtained.

[0144] Example 7

[0145] In this embodiment, an embodiment of a more preferred projector is described, which can be achieved by using an alumina ceramic plate as a diffuser plate.

[0146] Figure 18 This is a schematic diagram showing a cross-sectional view of the alumina ceramic plate that serves as the diffuser plate 26 in this embodiment. Figure 18 As shown, the alumina ceramic plate is an aggregate of irregularly shaped alumina particles. Even without surface roughening, it exhibits the property of random transmission and reflection of incident light. Therefore, for example, even the emitted light Ao and Bo emitted at the same angle as shown in the figure contains not only light that has traveled the same path but also light that has traveled different paths, Ai and Bi. That is, even emitted light at the same angle contains light with different optical path lengths, thus effectively reducing speckle noise.

[0147] This section explains the mechanism of the diffuser plate. Figure 19 This is a diagram illustrating the focusing angle θi of the incident light relative to the diffuser plate and the diffusion angle θo of the emitted light in this embodiment. (See diagram for example.) Figure 19 As shown in (A), the incident light directed toward the diffuser plate 26 is focused by the condenser lens 25 and incident onto the diffuser plate 26 at a focusing angle θi. Furthermore, as... Figure 19 As shown in (B), the emitted light from diffuser 26 exits at a diffusion angle θo. Here, because light generally diffuses, a diffusion angle θo is used. Figure 20 The definition of the diffusion angle θo in this embodiment will be explained. Figure 20 This represents the intensity distribution of light emitted from diffuser 26, with the vertical axis representing intensity and the horizontal axis representing the angle of the diffused light relative to the normal to the diffuser. For example... Figure 20 As shown, the intensity decreases the further away from the center position. In this embodiment, the angle at which the intensity of the emitted light becomes 50% when the peak intensity of the emitted light is 100% is defined as the diffusion angle θo of the emitted light from the diffuser plate.

[0148] Next, calculate Figure 19 The diagram shows the relationship between the incident light focusing angle θi, the outgoing light diffusion angle θo, and the utilization efficiency of the B-beam. Here, in... Figure 21 This indicates that the calculation was simplified. Figure 3 (C) is an explanatory diagram illustrating the case where regions I, O, WI, and WO of the dichroic mirror 24 are converted into circular regions. Figure 21 In the example shown, as already explained, the model represents the highest utilization efficiency of B light, where area SWI = area SWO (β = 1). Furthermore, the shape of W varies depending on the specific characteristics of the region. Figure 13 (B), (C), (D) Figure 14 (B), (C), (D) Figure 16 (B), (C), (D) Figure 17 In any of the shapes shown in (B), (C), and (D), it can be converted to... Figure 21 A circular model.

[0149] Figure 22 This indicates the optical path near the diffuser in this embodiment. Figure 22 Let Xi be the diameter of the circular region of incident light, and Xo be the diameter of the circular region of outgoing light. Furthermore, L is the focal length.

[0150] Here, as described in Example 1, Figure 3 In structure (B), the light utilization rate E2 is R2×T2=R2×(1-(R2×β / α), without the use of region segmentation and diffuser plates based on transmission / reflection characteristics. Figure 3 The light utilization rate E1 in structure (A) is (R1×T1)=R1×(1-R1). Furthermore, the condition for E2>E1, as explained in Example 1, can be transformed into (SO-SWO) / SO>(SI-SWI) / SI. This formula can be further transformed into 1-SWO / SO>1-SWI / SI. When subtracting 1 from both sides and rearranging the inequality, it can be transformed into SWO / SO<SWI / SI, and further into SO / SWO>SI / SWI. Moreover, when multiplying both sides by SWO / SWI, it can be transformed into SO / SWI>(SI / SWI)×(SWO / SWI).

[0151] Here, SO / SWI is the ratio of the area of ​​the different characteristic regions WI (i.e., the cross-sectional area of ​​the B beam incident on the condenser lens 25) within the incident region I of the B light in the dichroic mirror to the area SO (i.e., the cross-sectional area of ​​the B beam returning from the condenser lens 25) of the region O of the B diffused light returning to the dichroic mirror. It represents the effect of expanding the cross-sectional area of ​​the B beam through the functions of the condenser lens 25 and the diffuser plate 26. Further, SI / SWI is... Figure 3 (B) is the reciprocal of the actual reflectivity R² in the structure. Furthermore, SWO / SWI is β, which has already been stated. Therefore, SO / SWI > (SI / SWI) × (SWO / SWI) can be transformed into SO / SWI > β / R².

[0152] Here, the region segmentation and diffuser plate based on the previously described transmission and reflection characteristics are not used. Figure 3 In (A), the preferred reflectivity of light B is R1 = 0.2, such as Figure 21 As shown, when different characteristic regions WI are included in the incident region I, since β = 1, SO / SWI > 1 / 0.2, i.e., SO / SWI > 5. That is, in order to exceed the B-light utilization rate in the existing method through the function of the diffuser 26, the SO / SWI area ratio needs to be more than 5 times.

[0153] SO is the area of ​​the incident region O of the diffused light, and SWI is the area of ​​the total internal reflection region WI, which is a region with different characteristics, within the incident region I of the incident light B. Therefore, in Figure 22 In this context, SO = π(Xo / 2) 2 SWI = π(Xi / 2) 2 Therefore, the condition for the area ratio of SO / SWI to exceed 5 times becomes π(Xo / 2). 2 >5×π(Xi / 2) 2 That is, Xo > √5 × Xi.

[0154] At this time, Figure 22 In this context, when the focusing angle θi is expressed using Xi and the focal length L of the condenser lens 25, it becomes the focusing angle θi = 2 × arcsin((Xi / 2) / L). Furthermore, when the diffusion angle θo is expressed using Xo and the focal length L of the condenser lens 25, it becomes the diffusion angle θo = 2 × arcsin((Xo / 2) / L). Considering these mathematical expressions, the condition for the diffusion angle Xo > √5 × Xi, which satisfies the condition that the area ratio of SO / SWI exceeds 5, becomes θo > 2 × arcsin((√5 × Xi / 2) / L).

[0155] Here, the overall proportions of the optical system of the light source device 2 are determined, in principle, based on the aperture size of the panel used in the image display elements 6R, 6G, and 6B, to determine various optical path lengths and beam openings with appropriate efficiency, with a slight allowance depending on the design of each optical element. As a specific example, when the aperture size of the panel used in the image display elements 6R, 6G, and 6B is approximately 0.6 inches, for example, it is preferable to... Figure 22 The focal length L is approximately 15mm, preferably... Figure 21 The area SWI is approximately 35 square millimeters. Regarding the aperture size of the panels used in the image display elements 6R, 6G, and 6B, considering the possibility of using panels of approximately 0.3 to 1.0 inches depending on the projector model, and further considering the margin in the design of each optical element of the aforementioned optical system, Figure 22 The permissible range for the focal length L is approximately 12mm to 30mm. Figure 21 The permissible range for the area SWI is approximately 25 square millimeters to 42 square millimeters. Furthermore, when converting the permissible range of 25 square millimeters to 42 square millimeters for the area SWI to the range of Xi, the permissible range for Xi is 5.64 mm to 7.31 mm.

[0156] The diffusion angle characteristics of the diffuser plate 26 cannot be easily adjusted using a projector model as the aperture size of the panel and the design parameters of the optical elements of the optical system of the light source device 2 used in the aforementioned image display elements 6R, 6G, and 6B. Therefore, in order to reduce the cost of the diffuser plate 26, it is preferable to use the same type of diffuser plate for multiple projector models with different panel aperture sizes. Thus, it is necessary to... Figure 22 The permissible range of focal length L is approximately 12mm to 30mm and as Figure 21 Within the allowable range of the area SWI (approximately 25 mm² to 42 mm²) (5.64 mm to 7.31 mm² within the allowable range of Xi), find the condition where the area ratio of SO / SWI exceeds 5 times the diffusion angle.

[0157] That is, within the entire range of the focal length L (approximately 12mm to 30mm) and the Xi (approximately 5.64mm to 7.31mm), the diffusion angle θo that satisfies the above condition θo > 2 × arcsin((√5 × Xi / 2) / L) is determined. In the above condition, the smaller L is, the larger the diffusion angle θo is; the larger Xi is, the larger the diffusion angle θo is. Thus, within the above allowable ranges of L and Xi, the maximum required value of the diffusion angle θo is when L is the minimum allowable range of 12mm and Xi is the maximum allowable range of 7.31mm (where the area SWI is the minimum allowable range of 25 square mm). Therefore, when L = 12mm and Xi = 7.31mm are substituted into the condition θo > 2 × arcsin((√5 × Xi / 2) / L), it becomes θo > 2 × arcsin((√5 × 7.31 / 2) / 12). Calculations show that θo > 86°.

[0158] That is, the diffuser used in the projector of this embodiment can be a diffuser that can exceed the B-light utilization rate of the conventional method and is a lower cost diffuser, provided that the diffusion angle θo > 86° is satisfied.

[0159] then, Figure 23 This table is an example of a diffuser plate used in the projector of this embodiment, comparing the use of an alumina ceramic plate with other methods. Figure 23In this paper, four methods are compared as diffuser plates. Method A uses the alumina ceramic plate described above as a reflective diffuser plate. Method B is a method of creating a frosted glass by sandblasting or etching both sides of the glass, and then adding a reflective mirror to its back to create a reflective diffuser plate. Method C is a method of using a metal surface with an embossed or recessed finish as a reflective diffuser plate. Furthermore, Method D is a method of creating a frosted glass by sandblasting or etching one side of the glass, and then adding a reflective mirror to its back to create a reflective diffuser plate. Furthermore, Method D is a method of creating a frosted glass by sandblasting or etching one side of the glass, and then adding a reflective mirror to its back to create a reflective diffuser plate (which can also be described as changing only one side of the glass to frosted glass, compared to Method B).

[0160] Here, Figure 23 This section presents a comparison of the substrate material, processing details, emitted light diffusion angle θo, noise levels such as spot, and cost for each method. First, regarding substrate material, method A uses only alumina ceramic plates, and method C uses only metal. Methods B and D require both transmission glass and reflectors. Therefore, considering the cost of the substrate material, methods B and D, which require multiple substrate materials, are less advantageous.

[0161] Furthermore, regarding the processing details, method A can be manufactured solely by stamping the alumina ceramic, without requiring any embossing or debossing. This is advantageous in terms of processing costs. Conversely, methods B, C, and D all require embossing or debossing on the reflective surface, which is disadvantageous in terms of processing costs.

[0162] Furthermore, regarding the outgoing light diffusion angle θo, the alumina ceramic method of method A generates irregularly diffused outgoing light regardless of the focusing angle of the incident light, and its outgoing light diffusion angle θo is as large as about 120°.

[0163] Next, in method B, the outgoing light diffusion angle depends on the incident light focusing angle. The outgoing light diffusion angle is the diffusion angle obtained by increasing the diffusion angle of the diffuser relative to the incident light focusing angle. For example, when the incident light focusing angle is about 14°, the diffusion angle increase effect of method B is about 30°, and the final outgoing light diffusion angle θo becomes about 14° + about 30° = about 44°.

[0164] Furthermore, in mode C, irregular diffused outgoing light is generated regardless of the focusing angle of the incident light, and the outgoing light diffusion angle θo is about 40°.

[0165] Finally, regarding method D, the outgoing light diffusion angle depends on the incident light focusing angle. The outgoing light diffusion angle is the diffusion angle increased by the diffusion plate relative to the incident light focusing angle. For example, when the incident light focusing angle is approximately 14°, because method D increases the diffusion angle by approximately 6°, the final outgoing light diffusion angle θo becomes approximately 14° + approximately 6° = approximately 20°.

[0166] Here, the emitted light diffusion angles of methods A, B, C, and D are compared with the condition θo > 86° for the diffusion angle of the low-cost diffusion plate of method B, which has a higher light utilization rate than existing methods. Only the alumina ceramic method of method A exceeds the condition, and can be said to be more preferred as the diffusion plate used in the projector of this embodiment. The other three methods do not meet this condition.

[0167] Next, regarding noise such as speckle, it is smaller than that of methods A and B, and medium or large compared to methods C and D. In this respect, the alumina ceramic method of method A is also superior.

[0168] Finally, considering the overall cost taking into account the substrate material and processing details, methods B and D, which require multiple substrate materials, are inevitably expensive, while methods A and C are relatively inexpensive. In terms of overall cost, method A, specifically the alumina ceramic method, is also superior.

[0169] Therefore, it can be seen that any comparison item is advantageous for the diffuser plate used in the projector of this embodiment, especially the diffuser plate made of alumina ceramic which fully satisfies the above-mentioned diffusion angle condition formula with a sufficient emission diffusion angle θo, has less noise such as spot, and is relatively inexpensive.

[0170] The projector of this embodiment described above provides a cost-effective projector with further improved B-light utilization by using a diffuser plate with an outgoing light diffusion angle satisfying θo > 86°. In particular, by employing a diffuser plate made of alumina ceramic, an even better projector can be achieved.

[0171] The embodiments have been described above; however, the present invention is not limited to the above embodiments, but includes various modifications. Furthermore, the above embodiments have been described in detail to make the present invention easy to understand, and are not necessarily limited to including all the structures described. Moreover, a portion of the structure of one embodiment can be substituted into the structure of another embodiment.

[0172] Explanation of reference numerals in the attached figures

[0173] 1: Optical system; 2: Light source device; 3: Illumination optical system; 4: Dichroic optical system; 6R, 6G, 6B: Image display element; 7: Photosynthesizing prism; 8: Projection lens; 21, 21-1, 21-2, 21-3: Light source; 22, 23: Lens; 24, 91, 92, 93: Dichroic mirror; 25, 27: Condensing lens; 26: Diffuser plate; 28: Phosphor wheel; 29: Electric motor.

Claims

1. A projector, characterized in that, include: The white light generating unit uses a blue laser as a light source to generate blue and yellow light, thereby generating white light containing the generated blue and yellow light. and An optical system that uses an image display element to modulate light from the white light generated by the white light generating unit and projects the modulated light. The white light generating unit includes: A dichroic mirror irradiated with blue light from a blue laser that serves as the light source; A first focusing lens that focuses blue light reflected or transmitted from the dichroic mirror; A diffuser plate that diffuses the blue light focused by the first focusing lens; A second focusing lens that focuses blue light transmitted from or reflected by the dichroic mirror; and A phosphor that emits yellow light when illuminated by blue light focused by the second condenser lens. The diffusion plate is an alumina ceramic plate. The dichroic mirror has a first region and a second region, wherein the first region has the property of transmitting one of blue light and yellow light while reflecting the other, and the second region has the property of either reflecting or transmitting both blue light and yellow light. Blue light incident from the light source onto the dichroic mirror is incident on the first region and the second region. The blue light contained in the white light output by the white light generating unit is obtained by the blue light diffused by the diffuser plate being transmitted through the first condenser lens and then reflected or transmitted through the dichroic mirror. The yellow light contained in the white light output by the white light generating unit is obtained by the yellow light emitted from the phosphor being transmitted through the second condenser lens and then reflected or transmitted through the dichroic mirror.

2. The projector as described in claim 1, characterized in that: In the dichroic mirror, the region that transmits blue light and reflects yellow light is designated as the first region, and the region that exhibits total internal reflection is designated as the second region. The blue light contained in the white light output from the white light generating unit is the blue light diffused by the diffuser plate, transmitted through the first condenser lens, and then irradiated by the dichroic mirror, thus passing through the first region. The yellow light contained in the white light output from the white light generating unit is the yellow light emitted from the phosphor that is transmitted through the second condenser lens and then reflected by the dichroic mirror in the first region.

3. The projector as described in claim 1, characterized in that: In the dichroic mirror, the region that reflects blue light and transmits yellow light is designated as the first region, and the region that exhibits full transmission characteristics is designated as the second region. The blue light contained in the white light output from the white light generating unit is the blue light diffused by the diffuser plate, transmitted through the first condenser lens, and reflected by the dichroic mirror in the first region. The yellow light contained in the white light output from the white light generating unit is the yellow light emitted from the phosphor that is transmitted through the second condenser lens and then irradiates the dichroic mirror and is transmitted through the first region.

4. A projector, characterized in that, include: The white light generating unit uses a blue laser as a light source to generate blue and yellow light, thereby generating white light containing the generated blue and yellow light. and An optical system that uses an image display element to modulate light from the white light generated by the white light generating unit and projects the modulated light. The white light generating unit includes: A dichroic mirror irradiated with blue light from a blue laser that serves as the light source; A first focusing lens that focuses blue light reflected or transmitted from the dichroic mirror; A diffuser plate that diffuses the blue light focused by the first focusing lens; A second focusing lens that focuses blue light transmitted from or reflected by the dichroic mirror; and A phosphor that emits yellow light when illuminated by blue light focused by the second condenser lens. The emitted light diffusion angle θo of the diffuser plate exceeds 86°. The dichroic mirror has a first region and a second region, wherein the first region has the property of transmitting one of blue light and yellow light while reflecting the other, and the second region has the property of either reflecting or transmitting both blue light and yellow light. Blue light incident from the light source onto the dichroic mirror is incident on the first region and the second region. The blue light contained in the white light output by the white light generating unit is obtained by the blue light diffused by the diffuser plate being transmitted through the first condenser lens and then reflected or transmitted through the dichroic mirror. The yellow light contained in the white light output by the white light generating unit is obtained by the yellow light emitted from the phosphor being transmitted through the second condenser lens and then reflected or transmitted through the dichroic mirror.

5. The projector as described in claim 4, characterized in that: The diffuser plate is an alumina ceramic plate.

6. The projector as described in claim 4, characterized in that: In the dichroic mirror, the region that transmits blue light and reflects yellow light is designated as the first region, and the region that exhibits total internal reflection is designated as the second region. The blue light contained in the white light output from the white light generating unit is the blue light diffused by the diffuser plate, transmitted through the first condenser lens, and then irradiated by the dichroic mirror, thus passing through the first region. The yellow light contained in the white light output from the white light generating unit is the yellow light emitted from the phosphor that is transmitted through the second condenser lens and then reflected by the dichroic mirror in the first region.

7. The projector as described in claim 4, characterized in that: In the dichroic mirror, the region that reflects blue light and transmits yellow light is designated as the first region, and the region that exhibits full transmission characteristics is designated as the second region. The blue light contained in the white light output from the white light generating unit is the blue light diffused by the diffuser plate, transmitted through the first condenser lens, and reflected by the dichroic mirror in the first region. The yellow light contained in the white light output from the white light generating unit is the yellow light emitted from the phosphor that is transmitted through the second condenser lens and then irradiates the dichroic mirror and is transmitted through the first region.

8. The projector as described in claim 5, characterized in that: In the dichroic mirror, the region that transmits blue light and reflects yellow light is designated as the first region, and the region that exhibits total internal reflection is designated as the second region. The blue light contained in the white light output from the white light generating unit is the blue light diffused by the diffuser plate, transmitted through the first condenser lens, and then irradiated by the dichroic mirror, thus passing through the first region. The yellow light contained in the white light output from the white light generating unit is the yellow light emitted from the phosphor that is transmitted through the second condenser lens and then reflected by the dichroic mirror in the first region.

9. The projector as described in claim 5, characterized in that: In the dichroic mirror, the region that reflects blue light and transmits yellow light is designated as the first region, and the region that exhibits full transmission characteristics is designated as the second region. The blue light contained in the white light output from the white light generating unit is the blue light diffused by the diffuser plate, transmitted through the first condenser lens, and reflected by the dichroic mirror in the first region. The yellow light contained in the white light output from the white light generating unit is the yellow light emitted from the phosphor that is transmitted through the second condenser lens and then irradiates the dichroic mirror and is transmitted through the first region.

Images