JPH03257443A - Image projecting device - Google Patents

Abstract

PURPOSE:To prevent an optical system from being complicated and to easily make a projected image in a focused state by introducing non-visible light to an least a part of a projection system so that a specified surface is irradiated with the light and using reflected light therefrom so that a distance to the specified surface may be detected. CONSTITUTION:As to the flux of infrared rays from a light emitting element 17, only S-polarized component is reflected by a polarizing beam splitter 12 an projected by a projecting lens 18 to an object 19. A part of the flux of the reflected light enters an infrared-ray receiving lens 20 and an image-formation sot is formed on a bisectional sensor 21. Since the position of the spot differs in accordance with the position of the substance to be projected 19, the sensor 21 is moved to a focusing position where the respective sensor outputs in two divisions of the sensor 21 are made equal by a controller and detects the distance state from the object. According to the detected result, the lens 18 is moved to make the projected image in the focused state. Even though the same projection system as in the case of visible light is used, the projected image is not influenced because the light is infrared rays.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an image projection device using a liquid crystal panel.

[Prior art] An image projection device using a conventional liquid crystal panel was developed in Japanese Patent Application Laid-open No. 1983
As shown in Japanese Patent Application Laid-open No. 13885, Japanese Patent Application Laid-Open No. 125791-1982, and Japanese Patent Application Laid-open No. 106785-1989, each image component is formed by a liquid crystal panel provided for each of R, G, and B image components. Images were combined using a dichroic mirror or the like and projected onto a predetermined surface such as a screen using a projection lens.

FIG. 7 is a block diagram of the apparatus shown in the above-mentioned Japanese Patent Application Laid-Open No. 13885/1985.

Of the white light projected from the light source 71, the P-polarized light passes through the polarizing beam splitter 72 and is absorbed by the absorption plate 77, and only the S-polarized light is reflected by the polarizing beam splitter 72. This reflected S-polarized light is separated into R, G, and B color lights by dichroic mirrors 73 and 74, and a reflective liquid crystal panel 75 is provided for each color light.
Projected to R, 75G, and 75B.

Each liquid crystal panel 75R, 75G, 75B rotates the plane of polarization of incident light (in this case, S-polarized light) by a voltage applied to each pixel according to an image signal.
Electrically Controlled Bir
efringence) type liquid crystal is used.

Therefore, each reflected light from each liquid crystal panel 75R, 75G, 75B has a different polarization component for each pixel depending on the image signal. These reflected lights are combined again by dichroic mirrors 73 and 74 and returned to beam splitter 72. At this time, the P-polarized component in each reflected light passes through the beam splitter and ritter 72 and is projected onto a screen (not shown) by a lens 76, which is a projection system provided at the next stage. The S-polarized component is reflected by beam splitter 72 and returns to light source 71.

In this way, since the beam splitter 72 serves as both a polarizer and an analyzer, each liquid crystal panel 75R,
75G and 75B do not require a polarizing plate, and the overall configuration is simplified.

In an image projection device with such a configuration, if the distance between the lens that is the projection system and the screen deviates from the focal length of the lens, the image projected on the screen will be distorted in focus, making it difficult to see. The distance between the lens and the screen must be kept equal to the focal length. AF system (automatic focus system) that realizes such a shooting system
is widely used in film cameras and video cameras, but has not been provided for image projection devices.

[Problem to be solved by the invention]

-E The conventional image projection device mentioned above is not equipped with a mechanism to detect whether the distance between the projection system and the screen matches the focal length, and the distance between the projection system and the screen is correct. It was difficult to confirm whether it was true or not.

The present invention has been made in view of the drawbacks of the prior art described above, and is an image projection device capable of detecting whether the distance between the projection system and the screen matches the focal length without complicating the optical system. The purpose is to provide

[Means to solve the problem]

The image projection device of the present invention includes: a liquid crystal panel that forms an image for projection; a light source that irradiates the liquid crystal panel with visible light; The projection system includes a shadow system that forms a projected image, and invisible light source means that is provided outside the projection system and generates invisible light, and the projection system at least partially generates invisible light from the invisible light source. is introduced and irradiated onto a predetermined surface, and the distance state to the predetermined surface is detected using invisible light reflected from the predetermined surface.

(Function) Invisible light for detecting the distance to a predetermined surface (screen, etc.) is irradiated onto the predetermined surface via a projection system that forms a projected image on the predetermined surface. It doesn't get complicated. Also, since invisible light is used,
There is no adverse effect on the projected image by visible light.

〔Example〕

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

The basic configuration of this embodiment is the same as that of the conventional example shown in FIG. 7, and an image is projected using reflected light using an ECB type liquid crystal plate. The two dichroic mirrors 13 and 14 are provided in order in the direction in which the polarizing beam splitter 12 reflects the S-polarized light (to the right in the drawing). The dichroic mirror 13 reflects light of wavelengths equal to or lower than the B component of the incident light upward in the drawing. Of the incident light, the dichroic mirror 14 reflects light of wavelengths equal to or higher than the R component in the drawing direction, and transmits light of other wavelengths. A liquid crystal panel 15R for the R component is provided on the end face of the dichroic mirror 14 on the side where light with a wavelength equal to or longer than the R component is reflected.
There is a liquid crystal panel 1 for the G component on the end face on the side where the transmitted light travels.
5G is installed. Dichroic mirror 13 B
A glass spacer 16 and a liquid crystal panel 15B for making the optical path length equal to that of the reflected light of the R component light and the G component light are provided in the above-mentioned order of the reflection direction on the end face on the side where the light having a wavelength equal to or lower than the component light is reflected. Light emitting element 1 as invisible light source means
Reference numeral 7 is provided to face the light source 11 that emits visible light across the polarizing beam splitter 12, and emits an infrared beam that is invisible light.

Furthermore, the projection system in this embodiment is configured as follows.

The S-polarized light component in the infrared beam emitted from the light emitting element 17 is emitted from the polarizing beam splitter 12 together with the reflected light from each liquid crystal panel 15R, 15G, and 15B.
The projection lens 18 projects the image onto the object 19 . The projection lens 18 is provided so as to be movable back and forth about the optical axis emitted from the polarizing beam splitter 12 to the object 19 to be projected, thereby adjusting the focal length. 2
The two-split sensor 21, which is an area-type infrared light receiving sensor, is provided to receive the above-mentioned infrared light reflected by the projection object 19, and is movable perpendicular to the moving direction of the projection lens 18. It is being

An infrared receiving lens 20 is provided between the two-split sensor 21 and the projection object 19 to allow the infrared light beam reflected by the projection object 19 to enter the two-segment sensor 21 .

The projection lens 18 and the two-split sensor 21 described above are driven by a control device (not shown) which together with them constitutes a detection means.

Next, the operation of this embodiment will be explained.

When an infrared beam is emitted from the light emitting element 17, this infrared beam is incident on the polarizing beam splitter 12, and the S-polarized component is reflected as described above. This reflected infrared light beam is projected onto a projection object 19 by a projection lens 18. Next, a part of the infrared light beam reflected by the projection object 19 is captured by the infrared receiving lens 20 to form an imaging spot on the two-split sensor 21 . The position of the imaging spot formed on the light receiving surface of the two-split sensor 21 differs depending on the position of the projection object 19. The control device detects the distance state of the projection object 19 by moving the two-split sensor 21 toward a focal point where each sensor output in two areas of the two-split sensor 21 is equal, and adjusts the projection lens according to the detection result. 18 to keep the image on the projection object 19 in focus.

As described above, in this embodiment, so-called infrared active type AF control is performed in the liquid crystal video projector. This AF control was able to have a simple configuration because part of the optical system was also used as the projection system of the liquid crystal video projector.

2 and 3 are a side view and a top view, respectively, showing the configuration of a second embodiment of the present invention.

In this embodiment, a cross dichroic prism 2 is used to separate and combine the RGB color lights that make up the projection system.
8, and a polarizing beam splitter 23 and a λ/2 plate 26 are provided as means for aligning the polarization state of the light incident on the cross dichroic prism 28. The other projection lenses for projecting the composite image light onto the object, the light emitting element for detecting the distance state, the infrared receiving lens, and the two-split sensor are the same as those shown in Figure 1. The same numbers as in FIG. 1 are given, and the explanation is omitted.

There are R on three sides of the cross dichroic prism 28.
-Reflective LCD panel 25R/25G for G-B customers
25B is provided. Each of these LCD panels 25R
- For 25G and 25B, an ECB type or a 45° twisted nematic type (TN type) is used, which rotates the plane of polarization of incident light by a voltage applied in accordance with an image signal.

A polarizing beam splitter 27 is provided adjacent to the end face of the cross dichroic prism 28 on the input/output side, and a mirror 24 is provided above the polarizing beam splitter 27 .

Furthermore, a polarizing beam splitter 23 is provided above the cross dichroic prism 28. The polarizing beam splitter 23 receives the light emitted from the light source 11 and has a total reflection surface 23b formed parallel to the active surface 23a, and its shape when viewed from the top is a parallelogram as shown in FIG. It is of shape. The working surface 23a is formed on the light source 11 side, and a λ/2 plate 26 is provided in the direction in which the reflected light is emitted.

0 Next, the operation of this embodiment will be explained.

The white parallel light from the light source 22 is incident on the beam splitter 23 and is separated into S-polarized reflected light (S') and P-polarized transmitted light (P') with respect to the working surface 23a. This S-polarized reflected light (S') passes through the λ/2 plate 26, so that its plane of polarization is rotated by 90 degrees to become P-polarized light (P'), which then heads toward the mirror 24. On the other hand, the P-polarized light (P') transmitted through the working surface 23a is totally reflected by the total reflection surface 23b and directly heads toward the mirror 24. That is, the light beam from the light source 22 is completely converted into P-polarized light (P') by the polarizing beam splitter 23 and the λ/2 plate 26, and is emitted toward the mirror 24.

Then, this P-polarized light (P') is totally reflected by the mirror 24 and enters the polarization beam splitter 27 located below.

As shown in FIGS. 2 and 3, the polarizing beam splitters 23 and 27 have working surfaces 23a and 27a of η
P-polarized light (
P'> becomes S-polarized light to the polarization beam splitter 27, where it is all irradiated and sent to the adjacent cross dichroic prism 2.
8 (ray S in the figure).

In this way, the S-polarized light incident on the cross dichroic prism 28 is separated into R, G, and B color lights by the cross dichroic mirror surfaces 28a and 28b (reflecting R light) and reflecting B light, respectively. The light is projected onto each liquid crystal panel 25R, 25G, and 25B for R-G-B light. Each of these liquid crystal panels 25R, 25G, and 25B has the property of rotating incident light according to an image signal, as described above. In the case of this embodiment, each liquid crystal panel 25R, 25G, 25
Since the incident light to B is S-polarized light, the reflected light has a P-polarized light component depending on each pixel and pixel signal. The reflected lights of each color are combined again by the cross dichroic prism 28 and re-injected into the polarizing beam splitter 27. Here, the polarizing beam splitter 27 functions as an analyzer, and the image light transmitted therethrough is projected via the projection lens 18.

On the other hand, the infrared light beam for AF is emitted from the light emitting element 17 and enters the beam splitter 27, where only the S-polarized light component is reflected. This reflected infrared light is projected onto the object 19 via the projection lens 18 .

The subsequent AF operation is performed in exactly the same manner as in the first embodiment. In this way, even in the liquid crystal projector using the cross dichroic prism, it was possible to realize an infrared active type AF system as in the first embodiment.

FIG. 4 is a diagram showing the configuration of a third embodiment of the present invention.

While the first and second embodiments used a reflective liquid crystal plate to form images, this embodiment uses a transmissive liquid crystal plate to form images. This embodiment includes a light emitting element 401 that emits an infrared beam, an infrared projection lens 402, an infrared reception lens 403, a knee split sensor 404 which is a two-area infrared reception sensor, a projection lens system 405, and a projection lens system. Drive system 406 that drives 405
, a projection object 407, a light source 408, and liquid crystal panels 409R, 4 that form R-G and 3B images, respectively.
09G, 409B, Dichroic mirror 411 that reflects blue light, Dichroic mirror 412 that reflects light with wavelengths below green, Dichroic mirror 413 that reflects light with wavelengths above green, Dichroic mirror 414 that reflects red and infrared light, Cold Mirror 415, Mirror 4
It is composed of 16.

The projection lens system 405 is provided to be movable between the dichroic mirror 414 and the projection object 407 via a drive system 406, and the two-split sensor 404 is provided to be movable perpendicular to the moving direction of the projection lens system 405. . The drive system 406 and the two-part sensor 404 are driven by a control device (not shown) as in the first embodiment.

The projection system of this embodiment will be explained below.

The light beam emitted from the light source 408 is separated into R, G, and B component color lights by dichroic mirrors 411 and 412, and then sent to each liquid crystal panel 409R.

It enters 409G and 409B. The B component light is reflected by the dichroic mirror 411 and the mirror 416 and enters the liquid crystal panel 409B. Each liquid crystal panel 409B
, 409G, the image light of the B component and the G component is
The light is synthesized by a dichroic mirror 413 and enters a dichroic mirror 414. dichroic mirror 4
14, R-component image light transmitted through the liquid crystal panel 409R and reflected by a cold mirror 415 is incident, and the image light of each component is combined by the dichroic cooler 414 and transmitted through the projection lens 405. Projection subject 4
Projected on 07.

On the other hand, the light beam emitted from the infrared light emitting element 401 reaches the cold mirror 415 via the projection lens 402, but since the cold mirror 415 has a property of transmitting infrared rays, the light beam is transmitted through the dichroic mirror 415. Head towards mirror 414. As a necessary characteristic of the dichroic mirror 414, if the purpose is only to project image light, it is sufficient to have a reflection characteristic only for visible red light. In order to reflect the infrared light that is detected, a material that has reflective properties up to infrared light is used. Therefore, the infrared light beam is reflected by the dichroic mirror 414, passes through the projection lens system 405, and is projected onto the object 407 to be projected. The infrared light beam reflected by the projection object 407 is imaged on the two-split sensor 404 via the infrared receiving lens 403. Similarly to the first embodiment, the control device moves the two-split sensor 404 toward the focal point where the outputs of the two regions of the two-split sensor 404 are equal, and moves the lens system 405 according to this movement amount to perform AF.
Perform the action.

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

In this embodiment, image synthesis is performed using a cross dichroic prism. A light emitting element that emits an infrared beam, a projection lens that serves as a projection system to project the infrared light, a projection lens system that projects the image light emitted from the cross dichroic prism onto the object to be projected, a drive system, an infrared receiving lens, and a bisecting system. The sensor is similar to that shown in FIG.
Since the AF control performed by driving these 6 is similar, the same numbers as in FIG. 4 are given and the explanation will be omitted.

The light beam emitted from the light source 515 is separated into R, G, and B component lights by a dichroic mirror 514 that reflects red light and infrared light, and a dichroic mirror 511 that reflects blue light.

These dichroic mirrors 511 and 514 are provided so that their surfaces are perpendicular to each other on the optical axis of the light source 515, and the B light component is reflected upward in the drawing, and the R light component is reflected downward in the drawing. , G light components are transmitted straight ahead. The cross dichroic prism 510 has the same characteristics as the dichroic mirrors 511 and 514, and has dichroic mirror surfaces 510b (B light reflection) and 510a (R light reflection) formed parallel to these dichroic mirrors 511 and 514, respectively. It has LCD panels 409R, 409G, and R-G-B for customers on three sides.
409B is glued. The liquid crystal panel 409B receives the B light reflected by the Dyck 70 mirror 511.
62, 5161, and each dichroic mirror 511, 514 is reflected on the liquid crystal panel 409G.
Light that has passed through and gone straight is incident. The B light reflected by the dichroic mirror 514 described above is reflected by the mirror 5163 and the cold mirror 515 and enters the liquid crystal panel 409R, and at the same time, the infrared light beam emitted by the light emitting element 401 is transmitted to the projection lens 402. cold mirror 515
is incident through the Each LCD panel 409R/409G
- The R9G and B image lights that have passed through 409B are combined at dichroic mirror surfaces 510a and 510b, and projected onto object 407 via projection lens system 405.

In this embodiment as well, AF is performed using the infrared light beam emitted from the light emitting element 406, similar to the one shown in FIG.
An action is taken. Therefore, the liquid crystal panel 509R
Only during the F operation, this infrared beam incidence point or the entire panel is set to be in the ON state (transmission state).

Under this condition 8, the infrared light beam passes through the liquid crystal panel 509R, is reflected by the dichroic mirror surface 510a, and is reflected by the projection lens 40.
It is projected through 5. The mechanism related to the subsequent AF control is completely the same as that of the third embodiment. In this way, as shown in this embodiment, an AF system can be realized even in a liquid crystal projector using a cross dichroic prism.

FIG. 6 is a diagram showing the configuration of a fifth embodiment of the present invention.

This embodiment performs image synthesis using a cross dichroic prism, similar to that shown in the fourth embodiment, and is an optical system that separates the luminous flux emitted from the light source into R, G, and B customer components. The only difference is that Since the other configurations are the same as those shown in FIG. 5, the same numbers as in FIG. 5 are given, and the explanation will be omitted.

In this embodiment, dichroic mirrors 611 and 614 for color separation are arranged in sequence on the output optical axis of a light source 615 at the same inclination. Da 9 Ichroic mirror 611 is dichroic mirror 5
11 and B similarly to the dichroic mirror surface 510b.
Reflect light components. The dichroic mirror 614 is G
Reflects light components. dichroic mirror 611
The B light component reflected by mirror 616. The light is turned back and incident on the liquid crystal panel 509B. In the dichroic mirror 614, the G light component and below are reflected and enter the liquid crystal panel 509G. This liquid crystal panel 509
The dichroic mirror 611 removes the B light component from the incident light to G, so that only the G light component remains. The emitted light from the light source 615, which has been transmitted through the dichroic mirror 614 and made into only the R light component, enters the liquid crystal panel 509R via the mirror 6162 and the cold mirror 515.

Thereafter, RG-8 images are synthesized using a dichroic prism 509 in the same way as shown in FIG.
Further, an AF operation using the infrared light beam emitted from the light emitting element 406 is performed.

(Effects of the Invention) 0 As explained above, the present invention uses an optical system to irradiate a predetermined surface with non-town vision light for detecting distance conditions using a projection system that forms a visible projected image. This has the effect that the distance state can be detected without complication and that it is easy to bring the projected image into focus.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a first embodiment of the present invention, FIGS. 2 and 3 are a side view and a top view, respectively, showing the configuration of a second embodiment of the present invention, and FIGS. 6 is a diagram showing the configuration of the third to fifth embodiments of the present invention, and FIG. 7 is a diagram showing the configuration of a conventional example. 11, 22.4oa; 50B, 615... light source,
12, 23.27... polarizing beam splitter, 13,
14.411-414.511.514.611.61
4... Dichroic mirror surface, 16... Glass spacer, 17, 401... Light emitting element, 18... Projection lens, 19, 407... Projection object, 20, 403-... Infrared receiving lens , 21, 404-
・Two-split sensor, 23a”・Working surface, 23b-・Total reflection surface, 24, 416.516+ ~ 51B3.61fi+,
61B□...Mirror 26...λ/2 plate, 28, 510-...Cross dichroic prism, 2
8a, 28b, 510a, 510b--dichroic mirror surface, 402--projection lens, 405--projection lens system, 406--drive system, 415, 515--cold mirror 15R, 15G, 15B, 25R ,25G, 25
B, 409R, 409G. 409B, 5098.509G, 509B...Liquid crystal panel.

Claims (1)

[Claims] 1. A liquid crystal panel that forms an image for projection, a light source that irradiates the liquid crystal panel with visible light, and a liquid crystal panel that projects the image of the visible light irradiated onto the liquid crystal panel onto a predetermined surface. The projection system includes a projection system that forms a visible projected image, and invisible light source means that is provided outside the projection system and generates invisible light, and the projection system is configured to emit light, at least in part, from the invisible light source. An image projection system characterized by having a detection means for introducing invisible light and irradiating the predetermined surface onto the predetermined surface, and detecting a distance state to the predetermined surface using the invisible light reflected by the predetermined surface. Device.