JPH05328376A - Liquid crystal projector - Google Patents

Abstract

(57) [Abstract] [Purpose] To suppress the deterioration of the contrast caused by the vertical movement of the illumination optical system when adjusting the vertical movement of the image due to the change in the angle of the incident light beam with respect to the LCD plate. Further, it is possible to obtain advantages as a vertical unit such as a small volume and good uniformity of the screen, though the horizontal unit can be freely arranged. In a liquid crystal projector having an image vertical movement adjusting mechanism that causes vertical movement of an illumination optical system, an LCD plate in which liquid crystal molecules are oriented so as to have a wide vertical field of view is used. Further, the LCD plate and various mirror systems are arranged with their long sides vertical, and image rotation mirrors 47 and 48 for rotating the image by 90 ° are provided. The increase in back focus at this time is dealt with by providing a relay lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector capable of projecting an image on an external screen or the like.

[0002]

2. Description of the Related Art FIG. 10 (a) is a side view conceptually showing a projection mechanism of a liquid crystal projector. In this figure, 61 is a projection lens system, and 62 is a liquid crystal display (LCD) plate in which a polarizing plate and a liquid crystal display element are combined, and an image to be projected is displayed. Reference numeral 63 is a condenser lens for condensing light rays on the entrance pupil of the projection lens 51, 64 is a reflector as a light reflecting plate, and 65 is a light source such as halogen or metal halogen.

The light emitted from the light source 65 is reflected by the reflector 64, condensed by the condenser lens 63 into parallel rays, transmitted through the LCD plate 62 and condensed by the projection lens system 61. Then, with the optical axis A as the center of the projection position, the image of the LCD plate 62 is projected on, for example, a screen installed outside.

In a projector or the like, the projected image is actually adjusted in the vertical direction as compared with the adjustment in the horizontal direction of the projection position. Therefore, there is known a liquid crystal projector provided with a mechanism for adjusting the projection position in the vertical direction.

FIG. 10 (b) is a side view conceptually showing a liquid crystal projector having a vertical position adjusting mechanism for the projection position. The same parts as those in FIG. 10 (a) are designated by the same reference numerals. As understood from this figure, for example, when the projected image is moved in the upward direction, the projection lens system 61, which can be moved up and down, is slid upward while keeping the position perpendicular to the LCD plate 62. Then, the actual optical axis B is offset with respect to the original optical axis A so as to be in the upward direction. However,
Since the amount of light entering the projection lens system 61 is reduced as it is, the illumination optical system including the light source 65 and the reflector 64 has a radius of the distance between the LCD plate 62 and the light source 65.
The D plate 62 and the optical axis A are configured to be movable in the up and down (vertical) direction so as to draw an arc motion around the intersection D of the optical axis A. In this case, the light from the light source 65 is moved downward as illustrated. The axis C and the optical axis B of the projection lens system 61 are made to coincide with each other so that the amount of light is efficiently taken into the projection lens system 61.

For example, when the amount of movement of the projection lens system 61 is y and the magnification is m, the optical axis B of the projected image is
Will move upwards from the original optical axis A by y + ym = y (1 + m), and the image displayed on the LCD plate 62 will be free from keystone distortion and focus blurring.
The image is projected on the external screen with the optical axis B as the center of the projection position.

The shape of the unit of the current color liquid crystal projector is, as conceptually shown in FIG. 11, classified into two types, that is, a horizontal type (g), according to the structure of its internal optical system.
And vertical type (h). In the figure, 66 is a dichroic mirror for color separation and composition, 67 is a projection lens system, and (i)
Is a virtual screen showing a projected original image screen, for example, a liquid crystal display screen. Assuming that the size of the virtual screen (i) is H × V as shown in the figure, due to the disposition form of the dichroic mirror 66, only a part of which is illustrated in the figure, in the case of the horizontal projector (g), its housing is provided. The depth and width of the vertical projector (h) are determined in relation to the horizontal dimension H of the screen.
In this case, the depth and height of the housing are determined in relation to the vertical dimension V of the screen, and the overall size, that is, the volume of the projector unit is smaller in the vertical type (h) and is smaller. ..

[0008]

As described with reference to FIG. 10, an optical axis offset mechanism for moving the projection lens system 61 up and down, and a light source 65 and a reflector 64 corresponding thereto are provided.
By providing a light amount adjusting mechanism for moving the illumination optical system up and down, it is possible to adjust the up and down of the projection position of the image.

However, L used in a liquid crystal projector
As the CD plate, an LCD plate (direct view type) of the type used in a conventional liquid crystal television device or the like is diverted from the viewpoint of production cost and the like.

Generally, an LCD plate cannot have a wide viewing angle because of its characteristics. This is because, for example, when the user looks at a direct view type liquid crystal television device or the like, the contrast of the image displayed on the LCD plate becomes unclear as the angle of the user's line of sight with respect to the LCD plate becomes shallower. It appears as a phenomenon that the screen becomes difficult to see.

Therefore, in general, the orientation angle of the liquid crystal molecules of the LCD plate is processed at the time of manufacture to widen the viewing angle of the LCD plate in a specific one direction. However, due to the characteristics of the LCD plate, the viewing angle can be wide only in one direction, and for example, the viewing angle cannot be wide in both the vertical and horizontal directions.

Therefore, in the case of a liquid crystal television device, considering the situation when the user is actually viewing an image, it is advantageous to have a wider viewing angle in the horizontal direction than in the vertical direction. An LCD plate that has been oriented to have a wide angle is used. Thus, for example, when a user looks at a direct view type liquid crystal television device or the like, the contrast of the image displayed on the LCD plate is unclear even if the angle of the user's line of sight with respect to the LCD plate becomes slightly shallow in the lateral direction. Can be prevented.

However, as in the liquid crystal projector described with reference to FIG. 10B, the light beam when the image vertical movement adjustment mechanism adjusts the image vertical movement is the LCD of FIG.
As shown in the cross-sectional view of the plate viewed from the side, the original optical axis E is vertically incident on the LCD plate 62, while the incident angles are shallower than vertical such as the optical axes F and G, for example.

As described above, since the LCD plate 62 in the conventional liquid crystal projector has a wide viewing angle in the lateral direction for a liquid crystal television device or the like, it is used.
Inevitably, the vertical viewing angle becomes narrow. Therefore, when the incident angle of the light ray on the LCD plate 62 becomes shallow, the black portion of the image displayed on the LCD plate 62 is not blackened by the leaked light and is projected, and the image projected on the screen has an overall contrast. There is a problem that it becomes an unclear blurry image.

Further, as a problem relating to the unit of the liquid crystal projector, it is important to reduce its size, and it is necessary to cope with variations in the projection optical system such as ceiling suspension and floor placement. However, if a vertical optical system is adopted to reduce the unit size,
As the size increases in the height direction, it becomes difficult to support hanging or hanging on a wall. On the contrary, if a horizontal type optical system is adopted, the variation of the projection optical system increases, but if the same liquid crystal panel is used, the size of the unit itself becomes larger than that of the vertical type. Further, the horizontal type optical system arrangement is more likely to break the uniformity of the screen than the vertical type in the color separation optical system and the color combining optical system, and therefore the vertical type is advantageous in this respect.

As described above, the conventional liquid crystal projector has both merits and demerits both in the horizontal type unit and the vertical type unit, and there is a problem in that whichever type is adopted.

[0017]

In order to solve the above-mentioned problems, the present invention can display an image for a color separation mirror and each separation optical path on an optical axis connecting a light source and a projection lens. The illumination optical system including a light source and a reflector has an optical axis offset mechanism having a projection mechanism in which an LCD plate and a color combining mirror are sequentially arranged, and the projection lens is movable up and down within a predetermined range. A liquid crystal projector having an image vertical movement adjusting mechanism including a light amount adjusting mechanism configured to be movable up and down so as to obtain an optimum light amount with respect to an entrance pupil of the projection lens according to the vertical movement of the projection lens. In this case, the liquid crystal molecules are aligned so that the viewing angle is wide in the vertical direction. Then, the projection mechanism using this LCD plate is mounted on a liquid crystal projector of vertical and horizontal units, or a liquid crystal projector of a type in which the image vertical movement adjusting mechanism is set stepwise by a predetermined amount.

Further, on the optical axis connecting the light source and the projection lens, a color separation mirror and an image display L for each separation optical path are provided.
In a liquid crystal projector in which a CD plate and a color combining mirror are sequentially arranged, and an image displayed on an LCD plate is projected on a screen through a projection lens, a color separation mirror, LC
The D plate and the color synthesizing mirror are vertically arranged vertically on the base chassis in the long side direction, and further, an image rotating mirror capable of rotating the image synthesized by the color synthesizing mirror by 90 degrees is provided. It is arranged so that an image rotation type liquid crystal projector is constructed. Further, a relay lens system is arranged before and after the image rotation mirror so that a real image is formed between the image rotation mirror and the projection lens.

[0019]

Operation: By using the LCD plate in which the liquid crystal molecules are oriented so that the viewing angle is wide in the vertical direction,
An image with clear contrast can be obtained even when the incident angle of the light source with respect to the plate becomes shallow.

Further, by providing the image rotation mirror, the LCD plate and the color separation / color combination mirror can be horizontally arranged on the base chassis, so that the volume is about the same as that of the conventional vertical projector. It is possible to enjoy the advantages of using the horizontal projector such as variations of the projection optical system. If the relay lens system is configured to include the image rotation mirror, a short back focus lens can be used as the projection lens.

[0021]

EXAMPLE FIG. 4 is a sectional view showing the structure of a transmissive LCD plate used in a liquid crystal projector or the like. The liquid crystal 24 is sandwiched between the glass substrates 22 and 22 coated with the electrode plate 23, and the outer peripheral portion thereof is sealed with a sealing material 25. Further, it is attached so that the polarizing plates 21 and 21 are sandwiched therebetween. In the case of a reflection type LCD plate, in addition to the above structure, a reflection plate is attached to the polarizing plate 21 on one side.

The glass substrate 22 is used for aligning liquid crystal molecules.
Is what is done to. For example, a rubbing method is mentioned as one of the orientation treatment methods. This rubbing method is a method in which the glass substrate surface is directly treated with a parallel orientation material and then the substrate surface is lightly rubbed in one direction with a cotton cloth or the like.

According to the present invention, an LCD plate having a wide vertical viewing angle is used in a liquid crystal projector. For that purpose, when manufacturing the LCD plate, the substrate surface of the glass substrate 22 of the LCD plate is provided with a vertical viewing angle. The LCD plate may be mounted on a liquid crystal projector by rubbing in a wide direction.

FIG. 1 shows, as a first embodiment of the present invention, a projection mechanism (comprising a UV cut filter, various mirror systems, condenser lenses, etc., described later) having an LCD plate with a wide vertical viewing angle. FIG. 3 is a conceptual diagram showing a configuration when mounted on a horizontal unit. As shown in the housing perspective view of FIG. 3A, the horizontal unit of the liquid crystal projector is a type in which the projection lens system 1 is provided in the horizontal housing 26 and is characterized by a high degree of freedom in installation form. is there.

As shown in the plan view of the horizontal type unit of FIG. 1A, the light beam emitted from the illumination optical system composed of the light source 16 and the reflector 15 is passed through the UV cut filter 14 and is passed through the dichroic mirrors 13 and 12 to R, Color is separated into G and B. Each of the decomposed light rays is reflected by the condenser lens 5 (reflected by the total reflection mirror 6 and made incident), 8, 11
The light is condensed by the LCD plates 4, 7 and 10 and is incident on the LCD plates 4, 7, and 10 by the polarizing plates of the respective LCD plates.
A monochrome image of is created. After that, the light rays as respective monochromatic images are transmitted through or reflected by the dichroic mirrors 2 and 3 (the light rays passing through the LCD plate 10 are total reflection mirrors 9).
The light is reflected by the dichroic mirror 2 to reach the dichroic mirror 2) and is subjected to color combination, and is projected by the projection lens system 1 onto an external screen or the like. Reference numeral 17 denotes a vertical movement shift mechanism portion of the projection lens system 1. Also, the LCD boards 4, 7, 10
Are equidistant from the projection lens system 1.

FIG. 1B is a side view of the horizontal unit. For the sake of convenience, only the illumination optical system including the LCD plate 10, the condenser lens 11, the UV cut filter 14, and the light source 16 and the reflector 15 as the projection mechanism is shown as a configuration diagram. As shown in the figure, in order to move the projected image in the upward direction, the projection lens system 1 is shifted upward by the vertical movement shift mechanism section 17 in parallel with the image display surface of the LCD plate 10, and projection is performed. The illumination optical system is moved downward to adjust the amount of light incident on the lens system 1.
As a result, the incident angle of the light ray on the LCD plate 10 becomes shallower than the vertical direction as shown by the optical axis H, but the LCD plate 10 is oriented so that the vertical viewing angle becomes wide, and therefore the contrast is clear. It is possible to obtain a simple monochrome image.

As a matter of course, also for the LCD plates 4 and 7 shown in FIG. 1A, those which have been subjected to orientation treatment so as to have a wide vertical viewing angle are used. Light rays incident on the projection lens system 1 are LCD plates 4, 7, and 10.
Since the single-color images obtained through the are combined, an image with clear contrast is projected as a result.

In this case, the viewing angle in the horizontal direction becomes narrower, but it is not a problem if the conventional upper and lower image qualities are replaced in the left and right, and the LCD plate is always provided in the horizontal direction. Since the light beam is incident vertically, there is no problem if the rubbing process is performed so that the contrast becomes maximum under this condition.

As a second embodiment, FIG. 2 is a side view conceptually showing the structure in which a projection mechanism having an LCD plate having a wide viewing angle in the vertical direction is mounted on a vertical unit. Similar parts are given the same reference numerals. The vertical unit of the liquid crystal projector is a type in which the projection lens system 1 is provided in the vertical housing 27, as shown in the housing perspective view of FIG. 3B, and it is advantageous that the housing has a small volume. Is. Also in this case, as in the first embodiment, the LCD plates 4, 7, 10 are moved by the vertical movement of the optical illumination system corresponding to the vertical movement adjustment of the image.
Even if the angle of incidence of the light ray (shown by the optical axis H (dotted line)) with respect to is shallower than vertical, it is possible to project an image with clear contrast.

Further, if the vertical movement shift mechanism section 17 and the illumination optical system are vertically moved in a stepwise manner, the mechanism for adjusting the projection position of the projected image can be simplified. That is, the vertical movement shift mechanism unit 17 shown in FIGS. 1 and 2 does not have an arbitrary vertical movement amount and is set to a predetermined amount stepwise, and accordingly, the optical illumination system moves vertically to a predetermined amount stepwise. A liquid crystal projector having an image vertical movement adjustment mechanism configured as described above is configured. Even if a projection mechanism having an LCD plate having a wide viewing angle in the vertical direction is mounted, the same effects as those of the first and second embodiments can be obtained.

As described above, by using the LCD plate which has been subjected to the alignment treatment so that the viewing angle can be widened in the vertical direction, the liquid crystal projector does not lose clear contrast even when the image is vertically adjusted. Further, since it can be realized only by changing the orientation treatment direction at the time of manufacturing the LCD plate, it is also advantageous in terms of cost and manufacturing process.

In the above embodiment, the rubbing method is mentioned as the method of aligning the liquid crystal molecules of the LCD plate.
It goes without saying that another alignment treatment method may be selected as long as it has the same effect.

Another embodiment of the present invention will be described below. The present embodiment is characterized in that it is an image rotation type liquid crystal projector provided with an image rotation mirror.

FIG. 5 is a conceptual diagram showing the configuration of the image rotation type liquid crystal projector when viewed from above, and a base chassis (not shown) is provided horizontally on the paper surface. In the figure, 31 is a light source, 32 is a reflector, 33 is a UV (ultraviolet) cut filter, 34 and 35 are dichroic mirrors for color separation, 36 is a total reflection mirror, 37, 38 and 39 are condenser lenses, and 40 is a projection lens. System, 41,
42 and 43 are LCD plates, 44, 45 and 46 are dichroic mirrors for color combination, and 47 and 48 are mirrors for image rotation.

As shown, in this embodiment, LC
One projection lens system is used for three D
The short side of is attached parallel to the base chassis. A light beam emitted from a light source 31 arranged at a rear portion on the optical axis of the imaging optical system shown by an arrow is reflected by a reflector 32 and transmitted through a UV cut filter 33, and for example, a B reflection R reflection dichroic mirror 34 and 35 separates into R, G, and B colors.

The color-separated light rays pass through the combination of the condenser lenses 37, 38, 39 and the LCD plates 41, 42, 43, respectively, and then are passed through the dichroic mirror 4.
4, 45, 46 are combined. The combined rays are
The first image rotation mirror 47 reflects the light vertically upwards on the paper surface, and the second image rotation mirror 48 reflects the light parallel to the paper surface in the direction of the projection lens system 40, so that it is reflected on a screen (not shown). Is projected.

FIG. 6 is a perspective view conceptually showing the arrangement relationship of the image rotation mirrors 47 and 48. The first image rotation mirror 47 is arranged in the long side direction with respect to the base chassis. Further, the second image rotation mirrors 48 are arranged with their short side directions inclined by 45 °, respectively, and as a result,
The incident light image (c) formed by the combined rays after passing through the LCD plate is rotated by 90 ° to become the projected light image (d), and the projection direction thereof is also deflected by 90 °.

7 and 8 show the image rotation mirror 4
It is a front view side view which looked at 7, 48 from the projection direction of an image, and shows the arrangement relation of both mirrors.

In the case of this embodiment, as shown in FIGS. 7 and 8, the image rotation mirrors 47 and 48 are provided with angle adjusters 49, 49 and 50, 50, respectively.
Is installed. Therefore, it is possible to change the image position on the screen by adjusting the incident position angle to the projection lens system 40 only by adjusting these adjusters, so that it is possible to shift the projection lens, the condenser lens and the optical illumination system. Even much easier to adjust.

Next, an embodiment in which FIG. 5 is further modified will be described. FIG. 9 is a diagram conceptually showing only the optical configuration in the present embodiment. Reference numerals 51 and 52 are relay lenses, and the other components are the same as those in FIG. 5 and are given the same reference numerals. ..

Since the image rotation mirrors 47 and 48 are provided, a projection lens having a long back focus is required, which increases the number of lens components, which makes production difficult and expensive. Image rotation mirror systems 47, 4 as part of the relay lens systems 51-52.
8 is taken in, and this relay lens system makes it possible to use a projection lens having a short back focus as the projection lens system 40. For example, the back focus of the projection lens needs to correspond to the distance from the entrance pupil to the LCD surface, and the image rotation mirror system is inserted between them to make it 200 mm or more. If a real image is formed in the middle, a back focus projection lens of about 35 mm can be used.

In this embodiment, the image rotation mirror systems 47 and 48 are fixed, and the adjustment of the image position on the screen is dealt with by the vertical movement of the projection lens system 40 (direction perpendicular to the paper surface in FIG. 9). In this case, the illumination optical system (31 and 32) is shifted in the direction of the arrow e in the figure (the direction parallel to the paper surface) in order to suppress the reduction of the incident light flux. In a liquid crystal projector that does not use an image rotation mirror, the illumination optical system responds to the vertical shift of the image in the same vertical direction, or moves vertically in an arc motion. Can be shifted in a plane parallel to the projector unit, which is advantageous in terms of size and weight.

[0043]

In the liquid crystal projector having the image vertical movement adjusting mechanism including the optical axis offset mechanism of the projection lens and the light quantity adjusting mechanism by the vertical movement of the illumination optical system, an LCD plate having a wide vertical field of view is used. Thus, it is possible to obtain a high-quality image with a clear contrast even when the incident angle of the light ray on the LCD becomes shallow. Further, in this case, since the above effect is realized by performing the alignment treatment on the LCD plate, the manufacturing process is not complicated and the cost is low.

Further, in the image rotation type liquid crystal projector, the unit size is smaller than that of the conventional horizontal type and can be miniaturized, and it can be realized with the same volume as the vertical type. Further, since the height of the unit can be realized in the conventional horizontal type, it is possible to give variations to the projection optical system such as floor-standing, ceiling-mounted, wall-mounted.
Moreover, in this case, the shift adjustment of the image position can be more easily performed by changing the position and angle of the image rotation mirror regardless of the shift of the projection lens and the illumination optical system.

Further, with respect to the increase of the back focus of the projection lens, it is possible to avoid the difficulty of lens design by using the relay lens system. Then, in this case, the reduction of the light amount due to the vertical adjustment of the image position on the screen can be easily suppressed by shifting the illumination optical system in the plane parallel to the unit.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a perspective view of a housing in the embodiment of the present invention.

FIG. 4 is a sectional view of an LCD plate.

FIG. 5 is a conceptual diagram showing the configuration of another embodiment of the present invention.

FIG. 6 is a perspective view conceptually showing an arrangement relationship of image rotation mirrors.

FIG. 7 is a front view of a projection direction of an image on an image rotation mirror.

FIG. 8 is a side view of the image rotation mirror in the projection direction of an image.

FIG. 9 is a diagram conceptually showing an optical configuration in another example of the present invention.

FIG. 10 is a conceptual diagram showing a configuration of a conventional liquid crystal projector.

FIG. 11 is an explanatory diagram of a conventional liquid crystal projector.

FIG. 12 is an explanatory diagram showing an incident angle of an optical axis with respect to an LCD plate.

[Explanation of symbols]

 1, 40 Projection lens system 4, 7, 10, 41, 42, 43 LCD plate 15, 32 Reflector 16, 31 Light source 17 Vertical movement shift mechanism part 22 Glass substrate 24 Liquid crystal 26 Horizontal unit 27 Vertical unit 47, 48 Image rotation Mirror 49,50 Adjuster 51,52 Relay lens

Claims (6)

[Claims] 1. A projection mechanism in which a color separation mirror, a liquid crystal display plate capable of displaying an image for each separation optical path, and a color combination mirror are sequentially arranged on an optical axis connecting a light source and a projection lens, The projection lens has an optical axis offset mechanism configured to be movable up and down within a predetermined range, and an illumination optical system including a light source and a reflector is provided with respect to an entrance pupil of the projection lens corresponding to the vertical movement of the projection lens. In a liquid crystal projector having an image vertical movement adjusting mechanism composed of a light amount adjusting mechanism configured to be movable up and down so as to obtain an optimum light amount, the liquid crystal display plate has a liquid crystal molecule of a wide viewing angle in the vertical direction. A liquid crystal projector characterized by being subjected to an alignment treatment. 2. The liquid crystal projector according to claim 1, wherein the projection mechanism and the image vertical movement adjustment mechanism are mounted on a horizontal housing. 3. The liquid crystal projector according to claim 1, wherein the projection mechanism and the image vertical movement adjustment mechanism are mounted on a vertical housing. 4. The liquid crystal projector according to claim 1, 2, or 3, wherein the image vertical movement adjusting mechanism is set stepwise by a predetermined amount. 5. A color separation mirror, a liquid crystal display plate capable of displaying an image for each separation optical path, and a color combination mirror are sequentially arranged on an optical axis connecting a light source and a projection lens, and are projected on a screen through the projection lens. In a liquid crystal projector capable of projecting an image displayed on a liquid crystal display plate, the color separation mirror, the liquid crystal display plate and the color composition mirror each have a short side horizontally on a base chassis,
Moreover, they are arranged upright with their long sides vertical, and on the optical axis connecting the light source and the projection lens, the image synthesized by the color synthesizing mirror is further rotated by 90 degrees. A liquid crystal projector having an image rotation mirror that can be guided to the projection lens. 6. A relay lens system is further arranged in front of and behind the image rotating mirror on the optical axis connecting the light source and the projection lens so that a real image is formed between the image rotating mirror and the projection lens. The liquid crystal projector according to claim 5, wherein: