Projection type display device

Abstract

To provide a projection type display device that can suppress images to be projected from darkening even if an amount of light decreases by an amount-of-light adjustment mechanism.SOLUTION: A phosphor 2 is irradiated with laser light to emit prescribed color illumination light. A condenser lens 22 is arranged right behind a side where the illumination light is radiated with respect to the phosphor 2, and condenses the illumination light. A movement mechanism 62 moves the phosphor 2 in a direction where the phosphor gets close to the condenser lens 22 and in a direction where the phosphor leaves from the condenser lens 22. Image display elements 10R, 10G and 10B modulate the illumination light in accordance with the image to generate image light. An amount-of-light adjustment mechanism (an aperture 31 and an iris 32) changes, for adjusting contrast of the image to be projected, a size of the aperture through which the illumination light or the image light passes to thereby adjust an amount of light of the image light. The control unit 50 controls the movement mechanism 62 so that a distance between the phosphor 2 and the condenser lens 22 is a distance corresponding to an F-number in accordance with an adjustment state of the amount of light of the image light by the amount-of-light adjustment mechanism.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a projection display device. [Background technology]

[0002] As described in Patent Document 1, there is a projection display device that irradiates a phosphor with blue laser light emitted from a blue laser diode and projects an image using illumination light emitted by the phosphor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-82645 Summary of the Invention [Problem to be solved by the invention]

[0004] Projection display devices are equipped with a light amount adjustment mechanism called an aperture or iris to adjust the contrast of a projected image. When the light amount adjustment mechanism reduces the amount of light to increase contrast, the projected image becomes dark. It is desirable to minimize the darkening of the image when the light amount adjustment mechanism reduces the amount of light to increase contrast.

[0005] The present invention aims to provide a projection display device that has a phosphor that emits illumination light when irradiated with laser light, and that can prevent the projected image from becoming dark even when the light amount is reduced by a light amount adjustment mechanism. [Means for solving the problem]

[0006] The present invention provides a projection display device comprising: a phosphor that is irradiated with laser light and emits illumination light of a predetermined color; a focusing lens that is positioned immediately behind the phosphor on the side from which the illumination light is emitted and focuses the illumination light; a movement mechanism that moves the phosphor toward and away from the focusing lens; an image display element that modulates the illumination light according to an image to generate image light; a light intensity adjustment mechanism that adjusts the amount of image light by changing the size of an opening through which the illumination light or the image light passes in order to adjust the contrast of the projected image; and a control unit that controls the movement mechanism so that the distance between the phosphor and the focusing lens is a distance corresponding to an F-number that is in accordance with the adjustment state of the amount of image light by the light intensity adjustment mechanism. [Effects of the Invention]

[0007] According to the projection display device of the present invention, a phosphor is provided that emits illumination light when irradiated with laser light, and the projected image can be prevented from becoming dark even when the light amount is reduced by the light amount adjustment mechanism. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a projection display device according to an embodiment; [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of a brightness measurement device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a projection display device according to an embodiment will be described with reference to the accompanying drawings. In Fig. 1, a projection display device 100 according to an embodiment includes a light source 1, a phosphor 2, a polarization conversion element (PCS (Polarization Conversion System)) 3, a dichroic mirror 4, a cross dichroic mirror 5, a dichroic mirror 6, reflective polarizers 7R, 7G, and 7B, a color synthesis prism 8, and image display elements 10R, 10G, and 10B.

[0010] The projection display device 100 also includes condenser lenses 20-22, a collimator lens 23, condenser lenses 26-29, fly-eye lenses 24 and 25, a projection lens 30, an aperture 31, an iris 32, a light intensity adjustment operation unit 33, reflecting mirrors 40-42, a control unit 50, a table holding unit 51, a rotation mechanism 61, and a movement mechanism 62.

[0011] The control unit 50 may be configured with a microprocessor such as a central processing unit of a microcomputer. The table storage unit 51 may be a memory included in the microcomputer, or may be a memory such as a ROM separate from the microcomputer.

[0012] The condenser lens 22 is disposed immediately behind the phosphor 2 on the side from which illumination light, which will be described later, is emitted from the phosphor 2. The condenser lens 22 is a plano-convex lens with a flat surface on the phosphor 2 side and a convex surface on the condenser lens 21 side, but it may also be a biconvex lens.

[0013] The light source 1 is configured, for example, with a laser array in which a plurality of blue laser diodes BL are arranged. The number of blue laser diodes BL is not limited. The light source 1 emits blue laser light as blue illumination light. In FIG. 1, B indicates the blue illumination light or blue image light described below. The condenser lens 20 condenses the blue illumination light emitted from the light source 1. The dichroic mirror 4 reflects the blue illumination light emitted from the condenser lens 20 and bends the optical path of the blue illumination light by 90 degrees. The condenser lenses 21 and 22 condense the blue illumination light and direct the condensed blue illumination light to enter the phosphor 2.

[0014] Phosphor 2 has a fluorescent layer that generates yellow illumination light containing red and green band components with an intensity corresponding to the energy intensity of the incident blue illumination light, and a reflective surface. A portion of the incident blue illumination light is incident on the fluorescent layer of phosphor 2, generating the yellow illumination light. The reflective surface of phosphor 2 reflects the generated yellow illumination light and the other portion of the incident blue illumination light. Thus, phosphor 2 emits blue illumination light and yellow illumination light. In FIG. 1, Y represents yellow illumination light.

[0015] The phosphor 2 may have a fluorescent layer for generating red illumination light and a fluorescent layer for generating green illumination light, instead of the fluorescent layer for generating yellow illumination light, and may be configured to generate red illumination light and green illumination light separately. The phosphor 2 may be irradiated with laser light and emit illumination light of a predetermined color.

[0016] The phosphor 2 is circular, and Fig. 1 shows a side view of the circular phosphor 2. In order to suppress a rise in temperature of the phosphor 2 and to extend the life of the phosphor 2, the phosphor 2 is configured to rotate by a rotation mechanism 61. The control unit 50 controls the rotation of the phosphor 2 by the rotation mechanism 61.

[0017] The blue illumination light and yellow illumination light emitted from the phosphor 2 are transmitted through the condenser lens 22, the condenser lens 21, and the dichroic mirror 4 in this order, and are incident on the collimator lens 23. The collimator lens 23 converts the incident blue illumination light and yellow illumination light into parallel rays, which are incident on the reflecting mirror 40.

[0018] Reflecting mirror 40 reflects the blue illumination light and yellow illumination light, bending the optical paths of the blue illumination light and yellow illumination light by 90 degrees, and makes them incident on fly-eye lens 24. Fly-eye lenses 24 and 25 homogenize the illumination distribution of the incident blue illumination light and yellow illumination light. PCS 3 aligns the incident blue illumination light and yellow illumination light into p-polarized light. The blue illumination light and yellow illumination light emitted from PCS 3 are incident on cross dichroic mirror 5 via condenser lens 26. Cross dichroic mirror 5 separates the blue illumination light and yellow illumination light.

[0019] The reflecting mirror 41 reflects the separated yellow illumination light, bending the optical path of the yellow illumination light by 90 degrees, and makes it incident on the dichroic mirror 6. The dichroic mirror 6 reflects the green wavelength band component contained in the yellow illumination light as green illumination light and transmits the red wavelength band component contained in the yellow illumination light as red illumination light, thereby separating the yellow illumination light into green illumination light and red illumination light. In FIG. 1, G represents green illumination light or green image light, which will be described later. R represents red illumination light or red image light, which will be described later.

[0020] The red illumination light separated by the dichroic mirror 6 is incident on the reflective polarizer 7R via the condenser lens 27. The red illumination light passes through the reflective polarizer 7R and is incident on the image display element 10R. The image display element 10R optically modulates the incident red illumination light in accordance with the red component of the image data and emits s-polarized red image light. The red image light is reflected by the reflective polarizer 7R and is incident on the color synthesis prism 8.

[0021] The green illumination light separated by dichroic mirror 6 is incident on reflective polarizer 7G via condenser lens 28. The green illumination light passes through reflective polarizer 7G and is incident on image display element 10G. Image display element 10G optically modulates the incident green illumination light in accordance with the green component of the image data and emits s-polarized green image light. The green image light is reflected by reflective polarizer 7G and is incident on color synthesis prism 8.

[0022] Reflecting mirror 42 reflects the blue illumination light separated by cross dichroic mirror 5, bending the optical path of the blue illumination light by 90 degrees and causing it to enter reflective polarizing plate 7B via condenser lens 29. The blue illumination light passes through reflective polarizing plate 7B and enters image display element 10B. Image display element 10B optically modulates the incident blue illumination light in accordance with the blue component of the image data and emits s-polarized blue image light. The blue image light is reflected by reflective polarizing plate 7B and enters color synthesis prism 8.

[0023] The reflective polarizing plates 7R, 7G, and 7B can be configured, for example, by a wire grid.

[0024] The color combining prism 8 reflects the blue and red image lights and transmits the green image light, combining the red, green, and blue image lights. The projection lens 30 projects the combined image light onto a screen (not shown) to display a full-color image.

[0025] In the projection display device 100 configured as described above, an aperture 31 is disposed between the fly-eye lens 24 and the fly-eye lens 25. An iris 32 is disposed inside the lens barrel of the projection lens 30. The aperture 31 is configured to be able to change the size of an opening (first opening) through which the blue illumination light and the yellow illumination light pass by widening or narrowing it. The iris 32 is configured to be able to change the size of an opening (second opening) through which the combined light emitted from the color combining prism 8 passes by widening or narrowing it.

[0026] By operating the light intensity adjustment operation unit 33, the user can adjust the size of the opening of either the aperture 31 or the iris 32, or both the aperture 31 and the iris 32, thereby adjusting the amount of image light projected by the projection lens 30. The aperture 31 and the iris 32 function as a light intensity adjustment mechanism that adjusts the amount of image light. The user adjusts the light intensity by operating the light intensity adjustment operation unit 33 in order to adjust the contrast of the projected full-color image.

[0027] Specifically, to increase the contrast of a full-color image, the user operates the light intensity adjustment operation unit 33 to reduce the size of the opening of at least one of the aperture 31 and the iris 32, thereby reducing the amount of light. The light intensity adjustment mechanism shown in FIG. 1 is configured to adjust the amount of light in multiple stages by combining multiple stages of adjustment of the opening size of the aperture 31 and multiple stages of adjustment of the opening size of the iris 32. The adjustment state of the amount of image light is determined by this combination. In this way, the amount of light can be adjusted in more stages than when the amount of light is adjusted by the aperture 31 or the iris 32 alone.

[0028] When the light amount is reduced by the light amount adjustment mechanism, the contrast improves, but the projected full-color image becomes darker. Therefore, the projection display device 100 is provided with a movement mechanism 62 that moves the phosphor 2 in the direction of the optical axis to adjust the distance between the phosphor 2 and the condenser lens 22. The movement mechanism 62 moves the phosphor 2 in a direction toward the condenser lens 22 and a direction away from the condenser lens 22. The control unit 50 controls the movement of the phosphor 2 by the movement mechanism 62.

[0029] The movement mechanism 62 integrally moves the phosphor 2 and the rotation mechanism 61 that rotates the phosphor 2. As an example, a ball screw may be rotated by a motor, and the base on which the phosphor 2 and the rotation mechanism 61 are mounted may be moved by the ball screw.

[0030] The yellow illumination light emitted from phosphor 2 is completely scattered light. Therefore, the larger the opening sizes of aperture 31 and iris 32, the closer phosphor 2 is to condenser lens 22, and the brighter the full-color image. The smaller the opening sizes of aperture 31 and iris 32, the farther phosphor 2 is from condenser lens 22, and the brighter the full-color image.

[0031] Therefore, when the opening sizes of the aperture 31 and the iris 32 are maximum, the control unit 50 controls the movement mechanism 62 to position the phosphor 2 at a position closest to the condenser lens 22, as indicated by the solid line. When the opening sizes of the aperture 31 and the iris 32 are minimum, the control unit 50 controls the movement mechanism 62 to position the phosphor 2 at a position farthest from the condenser lens 22, as indicated by the two-dot chain line. The control unit 50 controls the movement mechanism 62 to position the phosphor 2 between the position indicated by the solid line and the position indicated by the two-dot chain line, depending on the opening sizes of the aperture 31 and the iris 32.

[0032] The distance between phosphor 2 and condenser lens 22 that maximizes the brightness of a full-color image can be determined in advance using a brightness measuring device shown in Fig. 2. In Fig. 2, the same parts as in Fig. 1 are designated by the same reference numerals, and their description will be omitted. As shown in Fig. 2, the blue illumination light and yellow illumination light emitted from phosphor 2 and transmitted through condenser lens 22 and dichroic mirror 4 pass through first aperture 71, lens 73, and second aperture 72, and enter an integrating sphere type power meter 74 through opening 74a. First aperture 71 and second aperture 72 constitute an F-number adjustment aperture 70.

[0033] The opening of second aperture 72 may be small and fixed. Changing the size of the opening of first aperture 71 changes the F-number of the optical system of the brightness measurement device shown in Figure 2. Increasing the opening of first aperture 71 decreases the F-number, and decreasing the opening of first aperture 71 increases the F-number. The measurer adjusts the F-number in multiple steps using F-number adjustment aperture 70, and determines the distance between phosphor 2 and condenser lens 22 at which the brightness of the light emitted from dichroic mirror 4 is maximized at each F-number, as measured by power meter 74.

[0034] The measuring device for measuring the brightness of the light emitted from the dichroic mirror 4 is not limited to the integrating sphere type power meter 74 .

[0035] 1, table holder 51 holds a table, which is obtained in advance using the brightness measuring device shown in FIG. 2, showing the correspondence relationship between each F-number and the distance between phosphor 2 and condenser lens 22 at which the brightness of the light emitted from dichroic mirror 4 is maximized. The maximum brightness of the light emitted from dichroic mirror 4 means that the brightness of the projected full-color image is maximized. In other words, the table held in table holder 51 shows the correspondence relationship between each F-number and the distance between phosphor 2 and condenser lens 22 at which the brightness of the projected full-color image is maximized.

[0036] As described above, in order to adjust the contrast of the projected full-color image, the user operates the light intensity adjustment operation unit 33 to adjust the light intensity of the image light using the light intensity adjustment mechanism. A value indicating the state of the light intensity adjustment by the light intensity adjustment operation unit 33 is input to the control unit 50. The value indicating the state of the light intensity adjustment may be a value indicating a stage when the light intensity is adjusted in multiple stages. The control unit 50 converts the value indicating the stage of the light intensity adjustment into an F-number of the projection display device 100. The control unit 50 associates the F-number with the stage of the light intensity adjustment. Therefore, the table held in the table holding unit 51 indicates the correspondence between each F-number and the distance between the phosphor 2 and the condenser lens 22 at which the brightness of the projected full-color image is maximized at the stage of light intensity adjustment corresponding to that F-number.

[0037] The F-number of the projection display device 100 is determined according to the focal lengths of the multiple lenses included in the projection display device 100 and the opening sizes of the aperture 31 and iris 32. Therefore, the F-number of the projection display device 100 can be determined by calculation. The control unit 50 may store in advance an F-number corresponding to a value indicating the level of light intensity adjustment, or may determine the F-number by calculation each time the level of light intensity adjustment is changed.

[0038] The control unit 50 refers to the table held in the table holding unit 51 and reads out the distance between the phosphor 2 and the condenser lens 22, which is stored in association with the F-number corresponding to the value indicating the level of light intensity adjustment. The control unit 50 controls the movement mechanism 62 so that the distance between the phosphor 2 and the condenser lens 22 becomes the read-out distance. In this way, the control unit 50 controls the movement mechanism 62 so that the distance between the phosphor 2 and the condenser lens 22 becomes the distance corresponding to the F-number according to the adjustment state of the image light intensity by the light intensity adjustment mechanism.

[0039] Therefore, even if a user reduces the amount of image light by changing the size of the opening through which the illumination light or image light passes in order to increase the contrast of the projected full-color image, the degree to which the projected full-color image becomes dark can be minimized.

[0040] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. The configuration shown in Fig. 1 shows a three-panel projection display device 100 equipped with image display elements 10R, 10G, and 10B that modulate illumination light of three primary colors, but it may also be a single-panel projection display device equipped with an image display element that modulates illumination light of a single color. In other words, the projected image may not be a full-color image, but may be a monochrome image. [Explanation of symbols]

[0041] 1 light source 2. Phosphor 10R, 10G, 10B image display element 22 Condenser lens 31 Aperture (light intensity adjustment mechanism) 32 Iris (light intensity adjustment mechanism) 33 Light intensity adjustment operation section 50 control section 51 Table holder 61 Rotation mechanism 62 Moving mechanism BL Blue laser diode

Claims

1. a phosphor that emits illumination light of a predetermined color when irradiated with laser light; a condenser lens that is disposed immediately behind the phosphor on the side from which the illumination light is emitted and that condenses the illumination light; a movement mechanism that moves the phosphor toward the condenser lens and away from the condenser lens; an image display element that modulates the illumination light in accordance with an image to generate image light; a light amount adjustment mechanism that adjusts the amount of the image light by changing the size of an opening through which the illumination light or the image light passes in order to adjust the contrast of the projected image; a control unit that controls the movement mechanism so that the distance between the phosphor and the condenser lens corresponds to an F-number according to an adjustment state of the amount of image light by the light amount adjustment mechanism; A projection display device comprising:

2. The light amount adjustment mechanism includes: an aperture that changes the size of a first opening through which the illumination light passes in a plurality of steps; an iris that changes the size of a second opening through which the image light passes in a plurality of steps; Including, The adjustment state of the amount of image light is determined by a combination of the size stages of the first opening and the size stages of the second opening.

2. The projection display device according to claim 1.

3. a table holder that holds a table indicating a correspondence relationship between each F-number and a distance between the phosphor and the condenser lens at which the brightness of the projected image is maximized at a light intensity adjustment stage corresponding to each F-number, The control unit refers to the table, reads out the distance between the phosphor and the condenser lens that is stored in association with the F-number, and controls the movement mechanism so that the distance between the phosphor and the condenser lens becomes the read distance.

3. The projection display device according to claim 1.

Images