JPH03220541A - Projection type display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a projection display device for displaying video images, computer images, and the like. In particular, the present invention relates to a rear-type projection display device that uses a liquid crystal panel as a light valve and can realize a large screen with a compact size.

[Prior Art] A conventional projection type display device using a liquid crystal panel and a light valve has the optical configuration shown in FIG. 8. The one shown in Fig. 8 is commercialized by our company (Epson Video Projector-VPJ-7000). These are front-type projection display devices, but if these are used as a projection optical unit and housed in a cabinet, a rear-type projection display device can be constructed (FIG. 7).

Further, a prototype of a projection type display device consisting of three projection lenses has been announced.

[Problem M to be solved by the invention] However, if a rear-type projection display device is constructed using a conventional simple magnifying optical system, it will be subject to limitations such as keystone distortion unless the optical axis is perpendicular to the screen. Even if a folding optical system using mirrors was adopted, the thickness of the projection display device could not be reduced unnecessarily (Figure 6).
7th). A depth of 100 centimeters was required for a screen size of 100 inches diagonally. Furthermore, even in that case, the light utilization efficiency was low and a bright screen could not be realized.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to realize a large, thin projection display device with a bright screen.

[Means for Solving the Problems] A projection type display device of the present invention includes: a light source that generates light; a collimating unit that collects the light from the light source and converts it into a substantially parallel light beam; a light valve disposed at an angle with respect to the light valve and modulating the substantially parallel light beam and including a plurality of pixels; a first projection optical means for projecting the light modulated by the light valve; and the first projection optical system. a reflecting means disposed near a position where the real image of the light valve projected by the means is formed; a second projection optical means for projecting the light reflected by the reflecting means again; The reflecting means is a reflecting means consisting of a plurality of micro reflective surface rows (array) arranged at a pitch smaller than the size of the real image at that position of the pixel included in the light valve, and The light emitted from the second projection optical means changes its optical path on the screen surface along so-called contour lines on the screen that are approximately equidistant from the exit of the second projection optical means. and from each part of a plurality of paraboloids of revolution whose focal point is the exit aperture of the second projection optical means so as to emit the light toward the viewer in a direction substantially perpendicular to the screen surface. It is characterized by the formation of a plurality of fine structures.

[Function] As shown in FIGS. 1 and 2, the projection type display device configured as described above can project onto the screen with a diagonal optical axis (that is, a non-axial optical system (diagonal projection method)
), the projection display device can be made thinner. A simple simulation shows that in the case of 60° incidence, the depth can be reduced by 50% and the thickness can be reduced by half.

Furthermore, the projection type display device configured as described above adopts a diagonal projection method in order to reduce the thickness, and allows the projection light from the second projection lens to be incident on the screen at a shallow angle. Regardless, the light emitted from the screen is mainly emitted almost parallel to the screen toward the viewer, so the light is not scattered in extra directions where there is no viewer, and the light is efficiently directed only in the direction where the viewer is. I can tell you. Therefore, a bright screen without uneven brightness can be achieved (4th
(see figure).

Hereinafter, the present invention will be described in detail based on Examples. However, the present invention is not limited to the following examples.

[Example] FIG. 1(a) is a diagram showing the optical configuration of a projection type display device in Example 1 of the present invention, and FIG. 1(b) is a partially enlarged view thereof.

11 is a light source. A reflector 12 has the function of collecting light from the light sources 11 and converting it into a substantially parallel beam of light.

A liquid crystal light valve 13 modulates the substantially parallel light flux. Further, the thirteen liquid crystal light valves are arranged at an angle with respect to the substantially parallel light flux. A first projection lens 14 has a function of refracting the light modulated by the liquid crystal light valve by a lens action and providing a real image of the liquid crystal light valve enlarged from the original liquid crystal light valve. 15 is a reflecting means, and 14 first
The liquid crystal light valve is placed near a position where a real image of the liquid crystal light valve formed by the projection lens is formed. Moreover, its structure is as shown in Fig. 1(b), and the 14th
It has the function of reflecting the light projected by the 16 projection lenses toward the 16 second projection lenses. Further, the reflecting means 15 is composed of a plurality of micro reflective surface arrays (array) (18) that are long in the horizontal direction and short in the depth direction. A large number of these 18 micro reflective surface arrays are arranged in the vertical direction at a pitch smaller than the size of the real image of the 13 light valve pixels at that position. Therefore, it is possible to ignore the phase inversion in each area of the optical information divided and reflected by this reflecting means, and as a whole, correct display screen information cannot be transmitted to the second projection lens. can. A second projection lens 16 projects the light reflected by the reflecting means 15 onto a screen 17.

Further, FIG. 2 shows an example of a sectional view of the projection type display device of the present invention. 21 is a projection optical unit of the present invention. 22 is a reflecting means. 23 is a second projection lens. 24 is the screen. 25 is a cabinet.

This optical system of the present invention is a non-axial optical system, and its operation will be briefly explained.

First, light modulated by a liquid crystal light valve arranged at an angle with respect to the optical axis is refracted by a first projection lens, and a real image of the liquid crystal light valve is reflected by a reflecting means also arranged at an angle with respect to the optical axis. image on top. At this time, the actual image of the liquid crystal light valve is considerably deformed from the original shape of the liquid crystal light valve. Next, the light reflected by the reflecting means is refracted by the second projection lens, and the real image of the liquid crystal light valve formed on the reflecting means is again formed on the screen. At this time, the real image of the liquid crystal light valve, which has been considerably deformed, is compensated by the action of the second projection lens and returns to the original shape of the liquid crystal light valve.

In fact, since the projection type display device of the present invention was able to adopt the optical configuration of the off-axis optical system as shown in FIG. 1, the depth from the screen could be significantly reduced compared to the conventional method.

Further, FIG. 3 is a diagram showing the optical configuration of the projection optical unit of the color-compatible projection type display device according to the present invention.

31 is a light source. A reflector 32 has the function of collecting light from the light source 31 and converting it into a substantially parallel beam of light.

33 is a dichroic mirror that separates the substantially parallel light beam into three primary color lights of red, green, and blue. Reference numeral 34 denotes a reflecting mirror, which has the function of guiding the three primary color lights separated by the dichroic mirror to three liquid crystal light valves for modulating the respective color lights. 35 is a liquid crystal light bulb, and there are three light bulbs: one for red, one for periphery, and one for blue. These three liquid crystal light valves are arranged with the same inclination with respect to the optical axis of the colored light. 36 is a dichroic prism, and the red light modulated by the three liquid crystal light valves is
It has the effect of combining the three colored lights of green and blue into a single beam of light. A first projection lens 37 has the function of projecting the single color-combined light beam.

This is different from the projection optical unit of a conventional projection display device in that each of the three liquid crystal light valves is tilted with respect to the optical axis.

As mentioned above, these three liquid crystal light valves are arranged with the same inclination with respect to the optical axis of the colored light, so 37
It is optically identical to the projection lens and can be treated as a single liquid crystal light valve. As a result, even a single-color projection display device can be made as thin as the projection display device shown in FIG.

Next, the structure and operation of the screen of the projection type display device of the present invention will be explained using FIG. 4.

41 is a second projection lens from which projection light is projected toward the screen. 42 is a screen, and the direction of the projection light projected from the second projection lens is changed here.

Further, the surface of the 42 screens is arranged along so-called contour lines on the screen that are approximately equidistant from the exit port of the second projection optical device, so that the exit port of the projection optical device is the focal point. multiple paraboloids of revolution (43)
A large number of fine structures (44) each consisting of a portion of are formed.

FIG. 5 is an external view of the screen of the present invention explained in FIG. 4.

51 is a screen, 52 is a contour line pattern formed on the screen, and it can be seen that a pattern of a paraboloid of revolution with the second projection lens as the focal point is carved along the contour line pattern.

By configuring the screen and the second projection lens as described above, a diagonal projection method is adopted in order to reduce the thickness of the screen, and the projection light from the second projection lens is directed onto the screen. Even though it was incident at a shallow angle,
The projection light from the second projection lens changes its optical path on the screen surface, and can now be emitted toward the 45 viewers in a direction substantially perpendicular to the screen surface. Therefore, the projection display device of the present invention can efficiently transmit light only in the direction where the viewer is, without scattering light in unnecessary directions where there is no viewer, and can realize a bright screen without uneven brightness. Ta.

Moreover, both FIG. 4 and FIG. 5 are drawn in a simplified manner to explain the action. The actual structure on the screen is much finer.

Furthermore, if a high-resolution liquid crystal panel is used as the light valve used in the projection display device of the present invention, it is possible to display a wall-mounted HD display.
It can also be used with large, thin, high-definition display devices such as TVs, which have bright screens with even brightness.

(Comparative Example) FIG. 6 is a diagram showing the optical configuration of a conventional projection type display device, and FIG. 7 is a sectional view of the conventional projection type display device.

61 is a light source. Reference numeral 62 denotes a beam deflector which has the function of collecting light from the light source 61 and converting it into a substantially parallel beam of light. 63 is a liquid crystal light valve that modulates the substantially parallel light flux. 64 is 6
A projection lens that projects the light beam modulated by the liquid crystal light valve 3. 65 is a screen on which the light projected by the projection lens 64 is projected.

This optical system is a simple magnifying optical system, so if you configure a rear projection display device, you will be subject to limitations such as keystone distortion unless you project with the optical axis almost perpendicular to the screen, so we adopted a folding optical system using mirrors. However, it was not possible to reduce the thickness of the projection display device unnecessarily (
Figure 7). A depth of 100 centimeters was required for a screen size of 100 inches diagonally. Also,
Even in that case, the light usage efficiency was low and a bright screen could not be achieved. Moreover, the brightness of the screen was different between the center and the periphery of the screen, and the display quality was poor.

71 is a conventional projection optical unit. 72 is a reflective mirror. 7
3 is the screen. 74 is a cylinder.

Further, FIG. 8 shows an example of a projection optical unit of a conventional projection type display device. 81 is a light source. 82 is a reflector.

83 is a dichroic mirror. 84 is a reflective mirror. 85
is an LCD light bulb. 86 is a dichroic prism.

87 is a projection optical means.

It can be seen that all three of the 84 liquid crystal light valves are not tilted with respect to the optical axis.

[Effects of the Invention] The projection type display device of the present invention comprises: a light source that generates light; co-1 nometer means for collecting the light from the light source and converting it into a substantially parallel light beam; a light valve disposed with an inclination that modulates the substantially parallel light beam and includes a plurality of pixels; a first projection optical means for projecting the light modulated by the light valve; consisting of a reflecting means disposed near a position where the projected real image of the light valve is formed, a second projection optical means for projecting the light reflected by the reflecting means again, and a screen; The means is a reflecting means consisting of a plurality of micro reflective surface rows (array) arranged at a pitch smaller than the size of the real image at that position of the pixel included in the light valve, and the screen includes the second The light emitted from the second projection optical means changes its optical path on the screen surface along so-called contour lines on the screen that are approximately equidistant from the exit of the projection optical means, and is directed toward the viewer. a plurality of fine structures each consisting of a portion of a plurality of paraboloids of revolution, each having a focal point at the exit aperture of the second projection optical means, so as to emit light in a direction substantially perpendicular to the screen surface; Because of this, it is possible to project with an optical axis diagonal to the screen (that is, an off-axis optical system (diagonal projection method) can be adopted), which has the effect of making the projection display device thinner. .

Furthermore, even though the diagonal projection method is adopted, light can be efficiently transmitted primarily only in the direction where the viewer is, so a bright screen can be realized.

Furthermore, if the resolution of the liquid crystal panel used as a light valve is increased, it is possible to realize a high-definition display terminal such as a wall-mounted HDTV that is large and thin and has a bright screen with uniform brightness.

[Brief explanation of drawings]

FIG. 1(a) is a partially enlarged view of the optical configuration of the projection type display device of the present invention. FIG. 2 is a cross-sectional view of the projection type display device of the present invention. Fig. 4 is a diagram showing the structure and operation of the screen of the projection display device of the present invention. Fig. 5 is a diagram showing the structure and operation of the screen of the projection display device of the present invention. External view. Figure 6 is a diagram showing the optical configuration of a conventional projection type display device. Figure 7 is a sectional view of a conventional projection type display device. Figure 8 is a projection optical unit of a conventional projection type display device. A diagram showing an example. 1... Light source 2... Reflector 3... Liquid crystal light valve 4... First projection lens 5... Reflection means 6... Second projection lens 7... Screen 8...Minute reflective surface 1...Projection optical unit 2 of the present invention...Reflection means 3...Second projection lens 4...Screen 5...Cylinder 1... Light source 32...Reflector 33...Dichroic mirror 34...Reflection mirror 35...Liquid crystal light valve 36...Dichroic prism 37...First projection optical means 41...Second projection Lens 42...Screen 43...Group of rotational paraboloids 44...Part of the screen 45 having a shape obtained by cutting out a part of the paraboloid of rotation...Viewer 51...Screen 52...・Constant height MAa on the screen 61... Light source 62... Reflector 63... Liquid crystal light valve 64... Projection optical means 65... Screen 71... Conventional projection optical unit 72... Reflection mirror 73... Screen 74... Cylindrical body 81... Light source 82... Reflector 83... Dichroic mirror 84... Reflection mirror 85... Liquid crystal light valve 86... Gichroic prism 87...Projection optical means or more

Claims (1)

[Scope of Claims] A light source that generates light, a collimating means that collects the light from the light source and converts it into a substantially parallel light beam, and a collimator that is arranged at an angle with respect to the substantially parallel light beam and that is arranged at an angle with respect to the substantially parallel light beam. a light valve that modulates a luminous flux and includes a plurality of pixels; a first projection optical means for projecting the light modulated by the light valve; a real image of the light valve projected by the first projection optical means; It consists of a reflecting means disposed near a position to be imaged, a second projection optical means for projecting the light reflected by the reflecting means again, and a screen, and the reflecting means is arranged in the vicinity of the pixel included in the light valve. The reflection means is made up of a plurality of micro reflective surface rows (array) arranged at a pitch smaller than the size of the real image at that position, and the screen is arranged at approximately the same distance from the exit aperture of the second projection optical means. Along so-called contour lines on the screen where A plurality of fine structures are formed, each consisting of a portion of a plurality of paraboloids of revolution, each having a focal point at the exit aperture of the second projection optical means, so as to emit light in a direction. Projection type display device.