MXPA98006048A - Proyecc presentation apparatus - Google Patents

Abstract

A projection display apparatus for projecting an image presented on an image display element on a screen is disclosed using light rays generated by a light source, wherein the polarized light separation mirrors of the sheet type each one having an inclined plane at an angle of 10 ° to 30 ° with respect to an optical axis of the light source, are placed between the image display element and the light source, whereby the projection presentation can be miniaturized at the reduced cost.

Description

"PROJECTION PRESENTATION APPARATUS" BACKGROUND OF THE INVENTION The present invention relates to an improved projection presentation apparatus for projecting an image presented on an image display element on a screen using light beams generated by a light source. A so-called projection display apparatus for projecting an image presented in an image display element on a screen using light beams generated by a light source is disclosed, for example, in Japanese Patent Numbers Hei-2-253247 and Hei-5-19209. The projection display apparatus disclosed in the above document employs a prism-type polarizer, and the projection display apparatus disclosed in the latter documents employs a polarizer composed of a plurality of glass sheets each having a Brewster angle. The prism-type polarizer and the polarizer that makes use of the Brewster angle are adapted to remove a component of light that is to be absorbed by the projection display apparatus and therefore to reduce the heat load imparted to it. an optical system of light rays generated by a light source; and to increase an optical efficiency of a polarized wave necessary by polarization conversion of a polarized and necessary wave. The projection display apparatus using the prism-type polarizer disclosed in the previous document, however, has a problem that the prism-type polarizer has a large size and is expensive. Meanwhile, the projection presentation apparatus using the glass sheets disclosed in the latter document, however, has a problem that the separation characteristic is physically limited depending on the Brewster angle and not necessarily, it is desirable. , and therefore, a desirable characteristic must be achieved by the use of a plurality of glass sheets.

COMPENDIUM OF THE INVENTION It is an object of the present invention to provide a projection display apparatus that can be miniaturized at a reduced cost. To achieve the aforementioned object, according to the present invention, a projection display apparatus for projecting an image presented on an image display element on a screen is provided using light rays generated by the light source including: polarized sheet-type light that separates the mirror with its inclined plane at an angle of 10 ° to 30 ° with respect to the optical axis of the light source, the mirror being placed between the image presentation element and the light source to separate a first polarized light component and a second polarized light component of one another, and convert either the first polarized light component or the second polarized light component, thereby uniting both components of polarized light either the first component of polarized light or the second component of polarized light. In accordance with the present invention, in the projection display apparatus for projecting an image presented in an image display element on a screen using the light rays generated by a light source, the polarized light of the sheet type separating the mirror of its inclined plane at an angle of 10 ° to 30 ° with respect to the optical axis of the light source is placed between the image display element and the light source. Accordingly, the mirror that separates the sheet-type polarized light is able to remove a light component that is to be absorbed in the projection presentation apparatus, thereby reducing a heat load that is applied to the optical system from the rays of light generated by the light source. The mirror that separates the polarized light from the blade type can be prepared at a lower cost than that of the prism-type polarizer and can be miniaturized because the plane thereof is inclined at a relatively small angle of 10 ° to 30 ° with respect to to the optical axis of the light source. If the angle of inclination of the plane is less than ° or greater than 30 °, it is difficult to separate sufficiently the first and second polarized light components from one another.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a television set as a preferred embodiment to which a projection display apparatus of the present invention is applied; Figure 2 is a sectional view of a television set, taken along the line -A of Figure 1; Figure 3 is a perspective view showing a preferred embodiment of the projection display apparatus of the present invention shown in Figure 2; Figure 4 is a plan view showing the projection display apparatus viewed from the direction shown by arrow Al of Figure 3; Figure 5 is a view showing the internal structure of the projection display apparatus shown in Figure 4; Figure 6 is a schematic view showing only an optical system of the projection display apparatus shown in Figure 5; Figure 7 is a perspective view showing an example of a PS conversion unit shown in Figures 5 and 6; Figure 8 is a view showing a positional relationship between the optical system of the PS conversion unit shown in Figure 7 and the light source; Figure 9 is a view showing a positional relationship between the polarized light separation mirror and the light source; Figure 10 is a diagram showing an example of the separation characteristic of the polarized light separation mirror; Figure 11 is a view showing an example of a first flying eye lens; Figure 12 is a view showing, in example, a second flying eye lens; Figure 13 is a view showing another example of the second flying eye lens; Figure 14 is a view showing another embodiment of the projection display apparatus of the present invention; Figure 15 is a view showing a further embodiment of the projection display apparatus of the present invention; Figure 16 is a view showing a further embodiment of the projection display apparatus of the present invention; and Figure 17 is a view showing a further embodiment of the projection display apparatus of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Next, the preferred embodiments of the present invention will be described with reference to the accompanying drawings.

It should be noted that while the following modalities will be described using specific terms, this description is for illustrative purposes only and it should be understood that the scope of the present invention is not limited to the modalities unless otherwise specified in terms of the limitation of the present invention. Figure 1 is a view showing the external appearance of a preferred embodiment in which a projection apparatus 1 of the present invention is applied, and Figure 2 is a sectional view taken along line A- of the Figure 1, showing the internal structure of a rear-side projection television set 100 of a liquid crystal type including the projection display apparatus 1 shown in Figure 1. A schematic structure of the television set 100 will first be described. Referring to Figures 1 and 2, the television game 100 houses a cabinet 101, a screen 102, a mirror 103 and the projection display apparatus 1. The light rays 5 to be projected which are formed from the light rays of a light source 3, leave the projection display apparatus 1, reflecting from the mirror 103 and projecting towards a rear face 104 of the screen 102. It should be noted that in the following description the term "projection" is equivalent to the term "incidence". An image projected on the screen 102 can be seen by a user U as in the black and white image or a color image. In describing the following embodiments, it is assumed that the color image is presented on the screen 102. A preferred embodiment of the projection display apparatus 1 shown in Figures 1 and 2 will be described below with reference to Figures 3 a 5. Figure 3 is a schematic view showing the external appearance of the projection presentation apparatus 1.; Figure 4 is a side view seen from the direction indicated by arrow Al, showing the projection display apparatus 1 of Figure 3; and Figure 5 shows an example of the internal structure of the projection display apparatus 1. In addition, Figure 6 shows diagrammatically an optical system of Figure 5. As shown in Figures 3 and 4, the projection display apparatus 1 includes a main body 11, a tubular body 13 of projection lens, a unit 15 PS conversion and a light source 3.

The main body 11 is integrated with the tubular projection lens body 13 which includes, as shown in Figure 5, a projection lens group 17 having various kinds of lenses 17a to 17i. The tubular body 13 of the projection lens has a mechanism capable of focusing the projection light rays (light rays of the image) 5 on the rear face 104 of the screen 102 shown in Figures 1 and 2. The body The main 11 removably retains the PS conversion unit 15, and has the following components. A first flying eye lens 21 and a second flying eye lens 23 are placed near the PS conversion unit 15 in such a manner as to be spaced apart from and parallel to each other. Along the optical axis OP from the second flying eye lens 23 to the group 17 of projection lenses are placed the following optical elements. That is, the dichroic mirrors 25 and 27, a relay lens 29, a mirror 31, a relay lens 33, and a mirror 35 are placed in this order from the second flying eye lens 23. Another mirror 37 is placed near the dichroic mirror, along an optic axis OPl perpendicular to the optical axis OP. In the region surrounded by the dichroic mirror 27 and the mirrors 35 and 37 a dichroic cube 41 is placed. A liquid crystal display apparatus (LCD: image display element) for blue (B) is placed between the dicromic cube 41 and a capacitor lens 43; a liquid crystal display apparatus (LCD: image display element) 49 for green (G) is placed between the dichroic cube 41 and a capacitor lens 47; and a liquid crystal display apparatus (LCD: image display element) 53 for red (R) is placed between the dichroic cube 41 and a slow 51 condenser. The dichroic mirror allows light in a specific wavelength region to pass through it and allows light in the remaining wavelength region to be reflected from it. As shown in Figures 4 to 6, the light source 3 is mounted on the main body 11 and as shown in Figure 5, the light source 3 has a reflector 55 and a lamp 57 which is represented by a halide lamp. of metal. The light beams L generated by the lamp 57 are reflected from the reflector 55 having a parabolic plane to be formed in essentially parallel light rays LP which are fed to the side of the PS concession unit 15. The PS conversion unit 15 will be described with reference to Figures 6 to 9. The PS conversion unit 15 functions as a polarization device PS for receiving the parallel light rays LP formed by the reflector 55 of the light source 3 which is they derive from it, for example only one S wave (polarized light component S: the first polarized light component) as shown in Figure 8. The parallel light LP beams contain a P wave (P the polarized light component) : the second component of polarized light) and an S wave (first component of polarized light). When the P and S waves pass through the PS conversion unit 15, only one wave, for example, the S wave is derived by the PS conversion unit 15. The S wave is then fed to the side of the first flying eye lens 21 shown in Figure 5. The PS conversion unit 15 has, as shown in Figures 7 and 8, a box 61, two separating mirrors 63. of sheet type polarized light (the sheet type polarized light separation mirror first and the second sheet type polarized light separation mirror), two one quarter wave plate mirrors 65 and one plate 67 half wave. The two mirrors 63 for polarized light separation are positioned in such a way that the plane of each mirror is inclined at an angle? specific with respect to the optical axis OP2 of Figure 5, as seen from the direction indicated by arrow 2, that is, seen in the direction parallel to the optical axis 0P2 of the tubular projection lens body 13 shown in Figures 5 and 6. That is, the two polarized light separation mirrors 63 are positioned symmetrically with respect to the axis Optical OP with each of the planes thereof inclined at an angle? with respect to the optical OP axis. The angle ? preferably it is graded within the range of 10 ° to 30 °, more preferably at about 20 ° C. If the angle? of the mirror 63 of polarized light separation becomes smaller than 10 °, the transmission for the S wave of the mirror 63 of the polarized light separation shown in Figure 8 becomes smaller and the necessary amount of the wave transmitted P becomes smaller. This is undesirable because it is difficult to separate P and S waves sufficiently from one another. If the angle? it becomes larger than 30 °, the transmittance for the S wave becomes longer, and the amount of transmittance of the P wave becomes smaller. This is undesirable because it is difficult to separate probes P and S sufficiently from one another. The half-wave plate 67 is mounted on the forward ends, which are open, of the polarized light separator mirrors 63 in such a way as to be perpendicular to the optical axis OP.

The PS conversion unit 15 shown in Figure 8 derives a desired wave, for example the S wave of the parallel LP light rays (containing the P and S probes), ie converts the polarization only from one of the separated light components. In the example shown in Figure 8, when the essentially parallel LP light rays enter the two polarized light separation mirrors 63 (incident angle: 90 ° -?, For example 70 °), the P wave passes through the the mirrors 63 that separate the polarized light, but the S wave is reflected from the mirrors 63 that separate the polarized light and reach the mirrors 65 of the one-quarter wave plate. The S wave is reflected from the mirrors 65 of a quarter wave plate and is fed in parallel to the optical axis OP. On the other hand, the wave P, which has passed through the mirrors 63 separating the polarized light is converted by polarization into the S wave by the half-wave plate 67 and is fed as the S wave in parallel to the optical OP axis . In this way, only the S wave is separated by polarization of the parallel light LP beams and fed to the subsequent first side of the flying eye lens 21. In this example, since only the S wave is used by removing the unnecessary polarized light component (P wave), a heat load applied to the incident side of the polarized sheet from the light rays generated by the light source 3 is can reduce, and the lighting efficiency of the S wave can also be increased. That is, even when the quality of the lamp light of the light source 3 is doubled, it is possible to suppress the low-temperature temperatures of the mirrors 63 separating the polarized light, the plate mirrors 65 of a quarter wave, the half-wave plate 67 and subsequent elements positioned from the flying eye lens to the projection lens system. Each mirror 63 that separates the polarized light preferably is coated with a single film of UNC2. With this configuration, the mirror 63 separating the polarized light can be prepared at a lower cost than that of a polarized light separation element of the prism type and also the incident angle (90 ° -?) Can be graduated to a large value , for example, of approximately 70 ° C. The first and second flying eye lenses 21 and 22 as an optical integrator shown in Figure 5 will be described. Figure 11 shows the first flying eye lens 21 and Figure 12 shows the second flying eye lens 23. The first flying eye lens 21 is formed by picking up in a plane the number of rectangular lenses 21a. The second flying eye lens 23 is formed by picking up in a plane four large central lenses 23a and several peripheral lenses 23b, 23c, 24d and 23e each being different in size from 23a. The first and second flying eye lenses 21 and 23 are placed behind the PS conversion unit 15 shown in Figure 5 to equalize the intensity distribution, for example the wave S formed by the PS conversion unit 15. The matched light rays are then fed to the dichroic mirror and shown later in Figure 5. In the second flying eye lens 23, each of the four lenses 23a placed in the central portion is graded to be larger than each one of the peripheral lenses in order to more efficiently receive the image of the lamp arch from the light source 3. Preferably, the central portion is divided into four parts where the four large-sized lenses 23a are placed. In the case where the incident angle of the LP-rays of parallel light from the light source 3 is large, (for example x2 as shown in Figure 12), that is, the size of the image formation of the LP-rays of parallel light is large in the central portion of the second eye lens 23, the large-size lens 23 is allowed to receive these light LP-rays. Conversely, since the incident angle of the parallel light LP beams is relatively small in the periphery portion of the second flying eye lens 23, the small-sized lenses 23c, 23d and 23e, for example, are placed in the peripheral portion. Figure 13 shows another example of each of the first and second vortex eye lenses 21 and 23 shown in Figures 11 and 12. As shown in this example, each of the flying eye lenses 21 and 23 can be replaced with the 121 flying eye lens having the lens 121a, which are equal in size to each other. Figure 10 shows the changes in transmittance (for the P wave or the S wave) of each mirror 63 of polarized light separation of the blade type of the PS conversion unit 15 with the wavelength of the light LP rays parallels obtained by the lamp of the light source 3 which is taken as a parameter. In this case, as shown in Figure 9, the incident angle of the P and S waves is graded to (90 ° -?). From the separation characteristic of the polarized separation mirror 63 shown in Figure 10, it becomes evident that the angle? of inclination of the mirror plane 63 of light separation polarized with respect to the optical axis is desired to be graduated, as described above in a scale of 10 ° to 30 °. It should be noted that the polarized light separation mirror exhibits the aforementioned separation characteristic preferably being coated with a Ti? 2 film. Then, an example of the operation of the projection display apparatus 1 housed in the television apparatus will be described. previously described. Referring first to Figure 5, the lamp 57 of the light source 3 generates uz rays that are formed in substantially parallel LP light beams. The parallel light LP beams enter the polarized light separation mirrors 63 of the PS conversion unit 15 shown in Figure 8. During this time, the P wave contained in the parallel light LP rays passes through the mirrors. 63 of polarized light separation, but the S wave is reflected from the polarized light separation mirrors 63, reaching the one-fourth wave plate mirrors 65 and reflected from them to be introduced as the S wave in parallel to the optical OP axis. In contrast, the P wave, which has passed through the polarized light separation mirrors 63, passes through the half-wave plate 67 to become the S wave. - 1! Accordingly, the PS conersion unit 15 operating as the PS converter derives only the S wave from the parallel light LP rays (containing the P and S waves) and removes the P wave as the unnecessary polarized light component. As a result, even when the amount of light from the light source 3 is greater, the heat quality thereof can be reduced so that it is possible to suppress the relatively low value temperatures of the polarized light separation mirrors 63 and the optical elements subsequent to them, and increase the lighting efficiency of the S wave. Since each of the polarized light separation mirrors 63 is inclined at an angle? relatively small, with respect to the optical axis OP as shown in Figure 8, the size of the box 61 of the PS conversion unit 15 shown in Figure 7 can be reduced, and since the mirror 63 of polarized light separation of the Leaf type is lower in cost than the prism-type polarized light separation element, it can be reduced to the total cost. The wave S obtained as shown in Figure 8 passes through the first and second flying eye lenses 21 and 23 to equalize and reach the dichroic mirror shown in Figure 5. Then, a part of the light rays is introduced. (S wave) to the dichroic mirror 27 and the remaining one is introduced to the common mirror 37. The light rays reflected from the mirror 37 pass through the condenser lens 51 and arrive at the liquid crystal display apparatus 53 for red (R). An image presented in the liquid crystal display apparatus 53, which is projected by the light rays from the mirror 37, is reflected from a semitransparent film 41a of the dichroic cube 41 and is introduced into the group 17 of the projection lenses. Part of the light rays arriving at the dichroic mirror 27 is fed to the relay lens 29 and the rest reaches the liquid crystal display apparatus 49 for the green (G) through the condenser lens 47. The image presented in the liquid crystal display apparatus 49 is projected by the light rays, which pass through the semi-transparent film 41a of the dichroic cube 41 and is introduced into the projection lens group 17. The light rays, which have passed through the relay lens 29, are reflected from the mirror 31, which passes through the relay lens 33, and is then reflected from the mirror 35 along the optical axis OP3. The light rays in this manner are bent essentially at 180 ° from the optical axis OP to the optical axis OP3, and are introduced into the liquid crystal display apparatus for the blue (B) through the condenser lens 43. An image presented in the liquid crystal display apparatus 45 is projected by the light rays, which are reflected from the semitransparent film 41b of the dichroic cube 41, and is introduced into the group 17 of projection lenses. The images of R, G and B are then superimposed on each other through group 17 of projection lenses to form the light rays 5 to be projected. The light rays 5 are reflected from the mirror 103 shown in Figure 2, and are projected onto the rear face 104 of the plant 102. The projected color image can be viewed from the front side from the screen 102 by the user U. The other embodiments of the present invention will now be described. Figure 15 shows another embodiment of the projection display apparatus of the present invention. A projection display apparatus 101 is different only in the structure of a PS conversion unit 115 from projection display apparatus 1 shown in Figure 8, and therefore, the description of the basic configuration is omitted.

The PS conversion unit 115 of the projection display apparatus 101 shown in Figure 15 has two sheet-type polarized light separation mirrors 163., two mirrors 165 of a quarter wave and two plates 167 of half wave. Like the embodiment shown in Figure 8, the polarized light separation mirrors 163 are positioned symmetrically with respect to the optical axis OP such that the plane of each mirror is inclined at an angle? with respect to optical OP, and the quarter-wave plate mirrors 165 are placed essentially in parallel to the polarized light separation mirrors 163. On the other hand, differently from the embodiment shown in Figure 8, each half-wave plate 167 is mounted between the polarized light separation mirror 163 and the quarter-wave plate mirror 165. When the essentially parallel LP light beams generated by the light source 3 enter the polarized light separation mirrors 163, the p wave passes through the polarized light separation mirrors 163, but the S wave is reflected therefrom. and it reaches the mirrors 165 of a quarter wave plate. The S wave is reflected from the mirrors 165 of the one-fourth wave plate and then converted to the P wave by the half-wave plates 167. That is, the PS conversion unit 115 can derive only the P wave from the parallel light LP beams by S-wave polarization conversion. Even in the case of using the P wave, like the embodiment in Figure 8 , the heat quality applied to the polarized light separation mirrors 163 of the PS conversion unit 115 can be reduced by up to about half, to suppress the temperatures of the optical elements to low values and to increase the optical efficiency of the optical component. polar light used. In this case, of the ratio described in the modality shown in Figure 8, the angle? it is preferably graduated within the range of 10 ° to 30 °, more preferably 20 °. In addition, the mirrors 163 for separating the polarized light are placed in the direction (perpendicular to the plane of the paper of Figure 15) perpendicular to the optical axis OP2 of the group 17 of projection lenses. Figure 16 shows a further embodiment in which the PS conversion unit 115 is placed between the first and second flying eye lenses 21 and 23. Figure 17 shows still a further embodiment in which the PS unit 115 is placed behind the second flying eye lens 23.

The arrangement that the examples show in Figures 16 and 17 can be applied to the PS conversion unit 15 shown in Figure 8. Figure 14 shows a projection display apparatus 201 as an additional embodiment in which the presentation apparatus 249 liquid crystal is placed between a 241 dichroic cube and 247 capacitor lens. The liquid crystal display apparatus 249 is an image display element for simultaneously projecting the images of three primary colors (R, G, B). With this arrangement, the number of optical system components can be significantly reduced. Also, the projection display apparatus 201 using a liquid crystal display apparatus 249 can be used for monochromatic presentation. The present invention is not limited to the aforementioned embodiments. While the liquid crystal display apparatus is not limited in particular in the aforementioned embodiments, the liquid crystal display apparatus can be represented, for example, by a liquid crystal display panel using a polycrystalline Si-TFT (transistor thin movie). Also, the TiO2 film formed in the polarized light separation mirror 63 shown in Figure 8 or the like can be replaced with other films produced for example from Zr 2 2, Ta2 5 5 and the material having a Refractive Index nd > 2.0. Even when the liquid crystal display apparatus is used as the image display element in the embodiments, the present invention can be applied to other display elements such as the liquid crystal display element of the reflection type. The light source is not limited to the type that uses a metal halide lamp. For example, other light sources such as a halogen lamp, a mercury lamp and a xenon lamp may be adopted. The projection display apparatus of the present invention can be applied not only to the type in which an image is projected on the back side of the screen shown in Figure 1 but also to the type where the image is projected directly on the front face from the screen. Even when a television viewing apparatus is used as the system for which the projection display apparatus is applied in the modes, the present invention can be applied to other monitors.

Claims (6)

R E I V I N D I C A C I O N S

1. A projection presentation apparatus for projecting an image presented on an image display element on a screen using light rays generated by a light source, comprising: a polarized light separation mirror of the sheet type with its inclined plane up to an angle of 10 ° to 30 ° with respect to an optical axis of the light source, the mirror is positioned between the image display element and the light source to separate a first polarized light component and a second polarized light component one of the other, and to convert either the first polarized light component or the second polarized light component, thereby uniting both polarized light components in either the first polarized light component or the second polarized light component.

2. A projection display apparatus according to claim 1, wherein the sheet type polarized light separating mirror is coated with a single Ti? 2-3 film. A projection display apparatus in accordance with Claim 1, wherein the light source generates essentially parallel rays of light, and the polarized light separation mirror is placed between the light source and an optical integrator. 4. A projection display apparatus according to claim 1, wherein the sheet-type polarized light separating mirror is composed of a first sheet-type polarized light separating mirror and a second part-separating mirror. polarized sheet-type light, the first and second sheet-type polarized light separation mirrors are placed symmetrically with respect to the optical axis of the light source. 5. A projection display apparatus according to claim 1, wherein the image display element is a liquid crystal display apparatus. 6. A projection display apparatus according to claim 1, wherein the image presented in the image display element is reflected from a mirror and then projected onto a rear face of the screen.