JPH08339259A - Projection display device - Google Patents

Abstract

PURPOSE: To perform an accurate instruction operation on a projection screen and to perform sure visual confirmation by providing a luminescent point display image formation means for preparing luminescent point display images based on luminescent point position information detected by a luminescent point position detection means. CONSTITUTION: An image formation means transmits light and outputs the projection light of images prepared on a liquid crystal panel 13 towards the projection screen. A luminescent point projection means projects a luminescent point composed of visible light to the projection screen. A polarizing beam splitter 5 is provided between an image focusing means and the image formation means and separates the projection light reflection components of screen emission light and luminescent point components whose polarizing direction is different from projection from the screen emission light and the projection light. The luminescent point position detection means detects the position of the luminescent point components of the screen emission light separated in an optical means. The luminescent point display image formation means prepares the luminescent point display images in the image formation means based on position information detected by the luminescent point position detection means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device used in a remote electronic conference using a communication line, a presentation in product description, a remote lesson system, and the like.

[0002]

2. Description of the Related Art A projection display device, which is also called a projector, is used as a device by which a large number of viewers can observe the display image on a projection screen at the same time at a presentation or a conference. Further, conventionally, by further developing such a projection display device, the contents written by the light pen on the projection screen are read, and the locus of the light pen is displayed, or with an input function for performing a specific process. Various projection display devices have been proposed.

For example, the projection display device described in Japanese Patent Application Laid-Open No. 4-299727 is constructed as shown in FIG. That is, the light from the high-intensity projection lamp 111 is converged by the Fresnel lens 120 and projected onto the back side of the liquid crystal panel 119. On the liquid crystal panel 119 which is illuminated by the high-intensity projection lamp 111, the displayed image is projected by the projection lens 1
The image is projected on the 07 side, and the display image is enlarged by the projection lens 107 and displayed on the projection screen 103.

On the other hand, the light pen 102 projects an infrared beam onto a desired position on the projection screen 103. Then, the display image on the projection screen 103 and the infrared beam are condensed on the position detection photodiode 123 by the reduction lens 121. At that time, reduction lens 1
Since the infrared filter 122 arranged between 21 and the position detection photodiode 123 transmits only the infrared beam, the position detection photodiode 123 detects only the infrared beam. In this way, the position of the light pen is detected as the position of the infrared beam. Then, based on the display position information of the infrared beam, a bright spot display image forming unit (not shown) projects a bright spot display image on the projection screen 10.
It is displayed by superimposing it on the display image on 3.

Further, the projection display device described in Japanese Patent Laid-Open No. 5-224636 is constructed as shown in FIG.
That is, by projecting the light from the light source 211 through the lens 220 to the back side of the liquid crystal panel 219, the display image of the liquid crystal panel 219 is projected on the front side of the liquid crystal panel. The display image projected from the liquid crystal panel 219 passes through the beam splitting mirror 230 and the projection lens 207 and is projected on the projection screen 203.

On the other hand, the radiation beam generated by the radiation projector 202 is reflected on the screen 203 together with the display image. Then, the display image and the radiation beam reflected by the screen 203 pass through the projection lens 207, and only the radiation beam is reflected by the beam splitting mirror 230. The radiation beam reflected by the beam splitting mirror 230 reaches the sensor means 223 through the image lens 231 and the image reduction lens 221. The sensor unit 223 supplies the position information of the radiation beam to a bright spot display image forming unit (not shown). The bright spot display image forming unit displays the bright spot display image and the like on the display image on the projection screen 203 on the basis of the input position information.

In the projection display device shown in FIG. 4, if the beam splitting mirror 230 does not transmit visible light, the liquid crystal panel 2
The display image of 19 is not accurately projected on the projection screen 203. Therefore, as the beam splitting mirror 230, a dichroic mirror that reflects only invisible light such as infrared light and transmits visible light is used, and infrared light is used as a radiation beam.

The projection display device described in Japanese Patent Laid-Open No. 6-236236 has a structure in which white light from a light source is divided into three basic components of blue, green and red and then added to various optical valves. In particular, it is configured as shown in FIG. That is, the white light of the light source 310 is reflected by the reflecting mirror 31.
1 and the optical system 312 and then collimated towards the modulation system. In the modulation system, first, the blue component of white light is converted into the first dichroic mirror 3
The light is reflected at 20, and a component having a wavelength longer than that of the blue component is transmitted. The component transmitted through the first dichroic mirror 320 reaches the second guichroic mirror 321. The second dichroic mirror 321 reflects the green component and transmits the red component. In this way,
White light is separated into three components, blue, green and red.

On the other hand, the first dichroic mirror 320
The blue component reflected by is guided to the optical valve VB by the simple mirror 330. The optical valve VB is a liquid crystal device and determines the blue component of the image by the blue component passing through. The green component reflected by the second dichroic mirror 321 passes through the optical valve VG. The optical valve VG is a liquid crystal device, and determines the green component of the image by the passing green component. The red component transmitted through the second dichroic mirror 321 passes through the optical valve VR. The optical valve VR is a liquid crystal device, and determines the red component of the image by the red component passing through.

The blue and green components of the image generated by the optical valves VB and VG are guided to the third dichroic mirror 322. The third dichroic mirror 322 reflects the green component and transmits the blue component having a shorter wavelength than the green component. Therefore, the blue component and the green component of the image are combined by the third dichroic mirror 322 and guided to the fourth dichroic mirror 323.

On the other hand, the red component of the image generated by the optical valve VR is reflected by the fifth dichroic mirror 324. The fifth dichroic mirror 324 reflects a red component and a wavelength shorter than the red component, while transmitting a component having a longer wavelength than the red component, that is, an infrared light component. The red component of the image reflected by the fifth dichroic mirror 324 is the fourth
It is guided to the dichroic mirror 323.

The fourth dichroic mirror 323 reflects the red component and the infrared component having a longer wavelength than the red component, while transmitting the wavelength shorter than the red component. Therefore,
The blue component, the green component and the red component of the image are combined by the fourth dichroic mirror 323 to form an objective lens 340.
Be led to. Each optical valve VB, VG, VR is an objective lens 3
Since they are arranged at the same distance with respect to 40,
The blue, green and red components combined at the output of the fourth dichroic mirror 323 are collected by the objective lens 340. Therefore, the enlarged image is displayed on the projection screen 35.
0 will be displayed on top.

On the other hand, the infrared light emitter 37 operated by the operator
Infrared light emitted from 0 forms an infrared light spot on the projection screen 350.

The display image reflected by the projection screen 350 and the infrared light refracted or reflected by the projection screen 350 reach the fourth guichroic mirror 323 through the objective lens 340. The red component of the display image and the infrared light reach the fifth dichroic mirror 324 after being reflected by the fourth guichroic mirror 323.
The fifth dichroic mirror 324 passes only infrared light,
The red component of the displayed image is reflected. Therefore, the objective lens 3
An infrared light spot is imaged on the infrared light surface detector 360 located at the same distance from 40 as the optical valves VB, VG, and VR. Then, the position of the infrared light spot on the projection screen 350 is detected from the position of the combined infrared light spot, and the position information is supplied to a bright spot display image forming unit (not shown). Then, in the bright spot display image forming unit, the bright spot display image is projected on the projection screen 35 based on the input position information.
It is displayed by superimposing it on the display image above 0.

[0015]

In the conventional example shown in FIG. 3, it is difficult to mount the projection screen of this type with high precision because of its structure, and therefore the projection screen 1
The mounting position and angle of 03 may change abruptly. When such a position change of the projection screen 103 occurs, the relationship between the image position projected on the projection screen 103 and the spot position of the infrared beam by the light pen 102 received by the reduction lens 121 does not match, As a result, there arises a problem that a shift occurs between the input position of the light pen 102 and the light pen instruction image that displays it.

In the conventional example shown in FIGS. 4 and 5, the dichroic mirror is used to separate the emitted light of the light pen from the emitted light of the screen. Therefore, the emitted light of the light pen is red. It must be invisible light such as outside light. However, it is often desired to perform the pointing position of the light pen while visually confirming it or to show only the pointing position of the light pen without displaying the trajectory of the light pen. However, with a light pen using invisible light, the pointing position cannot be visually confirmed, and it is necessary to separately provide a visible light source for visual confirmation, which has been a factor of cost increase.

Therefore, it is an object of the present invention to provide a projection display device capable of performing an accurate pointing operation on a projection screen and enabling reliable visual confirmation.

[0018]

In order to achieve such an object, in the present invention, light is transmitted through a liquid crystal panel so that projection light of an image created on the liquid crystal panel is directed toward a projection screen. An image forming means for outputting, an image forming means for forming an image of the projection light on the projection screen, and a means for condensing screen radiation light reflected or transmitted through the projection screen, and a bright light formed on the projection screen. It is provided between a bright spot projection means for projecting a point and the image forming means and the image forming means, and a projection light reflection component of the screen emission light from the screen emission light or the projection light or Optical means for separating bright spot components having different polarization directions from the projected light; bright spot position detecting means for detecting the position of the bright spot components of the screen radiation light separated by the optical means;置検 detecting means is characterized in that is a bright spot display image forming means for creating a bright spot displayed image based on positional information detected by the image forming means.

[0019]

The bright spots formed by the bright spot forming means are reflected or transmitted through the projection screen and then pass through the image forming means to reach the optical means. Further, the projection light formed by the image forming means also reaches the optical means after being reflected by the projection screen.
Here, the projection light is light that has passed through the liquid crystal panel and has a polarization direction aligned in a predetermined direction. Also, most of the projection light reflection component is light having the same polarization direction as the projection light. Therefore, the light that reaches the optical means includes two light components, that is, the projection light component of the projection light or the screen radiation light with the same polarization direction, and the light component of the polarization direction different from the projection light component of the projection light and the screen emission light. Will exist. The optical means separates these two lights by the difference in polarization direction.

In the bright spot light of the screen emitted light, that is, in the bright spot light reflected or transmitted through the screen, there exists a light component having a polarization direction different from that of the projected light component or the emitted light of the screen emitted light. , This light component is separated from other light by the action of the optical means described above.

In this way, the bright spot component of the screen radiation light separated from the other light components is detected by the bright spot position detecting means, and the bright spot display image is formed by the bright spot display image forming means based on the position information. Is formed and is projected and displayed on the projection screen.

At this time, the image forming operation of the projection light and the condensing operation of the screen radiation light are not performed separately but are performed together by the image forming means. Therefore, regardless of the mounting position accuracy of the projection screen, the relative positional relationship does not change between the projection light that has performed the imaging operation and the screen emission light that has performed the focusing operation.

Further, since the bright spot component is separated according to the polarization direction, there is no problem even if visible light is used for the bright spot.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a projection display component according to the first embodiment of the present invention.

This projection display device 1 has a projection screen A.
Projection display device main body 2 for outputting projection light of an image toward
And a light pen 3 as a bright spot projection means for projecting a bright spot on the projection screen A.

The main body 2 of the projection display device comprises an image forming means 4
A polarizing beam splitter 5 as an optical means, a light-receiving / receiving lens 6 as an image forming means, a CCD (solid-state image pickup device) 7 as a bright spot position detecting means, and a condenser for performing a condensing action on the CCD 7. A light unit 8, an image formation control unit 9,
And a power supply 10.

The light-receiving / receiving lens 6 is arranged on the optical axis of the image projection light of the image forming means 4, and the polarization beam splitter 5 is arranged between the light-receiving / receiving lens 6 and the image forming means 4. . Further, the CCD 7 is provided on the axis line that passes through the polarization beam splitter 5 and is orthogonal to the optical axis of the image projection light, and the condensing means 8 is arranged between the CCD 7 and the polarization beam splitter 5.

The image forming means 4 comprises a light projecting light source 12 having a reflecting plate 11, and a liquid crystal panel 13 arranged on the optical axis of the output light of the light projecting light source 12. LCD panel 1
Reference numeral 3 denotes polarizing plates 15A and 1A on both surfaces of the liquid crystal cell 14, respectively.
5B is attached and it is comprised. Polarizing plates 15A and 15B
So that the polarization directions are orthogonal to each other.
It is attached to 4.

The CCD 7 detects the bright spot light which is formed on the projection screen A by the light pen 3 and then reflected. Other than the CCD, the semiconductor position detector (P
SD) and the like can also be applied.

As the light source 12 for projecting light, a non-red light source such as a metal halide discharge lamp is suitable because of the amount of heat generation and the amount of light, but the light source 12 is not limited to this.

The reflecting plate 11 is arranged on the opposite side of the liquid crystal panel 13 in order to efficiently irradiate the liquid crystal panel 13 with the light from the light source 12 for projecting light, and may be a metal plate.
Reflective coated paper or plastic film may also be used.

The polarization beam splitter 5 is a cube-shaped polarizer in which a pair of right-angled prisms each having a dielectric multilayer film coating on the slopes are bonded to each other on the slopes. The polarization beam splitter 5 transmits light in a predetermined polarization direction while The direction reflects light of a polarization direction orthogonal to the direction. In this polarization beam splitter 5, the polarizing plates 15A and 15A of the liquid crystal panel 13 are
Light having a polarization direction that matches the polarization direction of the polarizing plate 15B on the side closer to the polarization beam splitter 5 of B, while having a polarization direction orthogonal to the polarization direction of the polarizing plate 15B, that is, the polarizing plate It reflects light in a polarization direction parallel to the polarization direction of 15A.

Therefore, the projection light of the liquid crystal panel 13 passes through the polarization beam splitter 5 and is output to the light-receiving / receiving lens 6 side. In addition, of the screen radiated light that is reflected by the projection screen A and condensed by the lens 6 for both light transmission and reception,
The projection light reflection component having the same polarization direction as the projection light passes through the polarization beam splitter 5.

On the other hand, of the reflected light of the bright spots formed on the projection screen A by the light pen 3, the bright spot reflected light component whose polarization direction is orthogonal to the projection light is the polarization beam splitter 5.
Is reflected by the CCD 7 side.

The light collecting means 8 is provided with a focusing screen 16 made of a ground glass plate and a detection lens 17. Focusing screen 16
Is provided at a position where the optical path length is the same as the optical path length of the liquid crystal panel 13 when viewed from the light-receiving / receiving lens 6. The detection lens 17 is provided between the focusing screen 16 and the CCD 7, and has a function of condensing the light transmitted through the focusing plate 16 and guiding it to the CCD 7.

By providing the condensing means 8 having such a configuration, the focal length of the screen radiated light is shortened and the reduction ratio thereof is increased as compared with the case of using the light-receiving / receiving lens 6 alone. Therefore, the distance between the CCD 7 and the polarization beam splitter 5 is shortened to reduce the overall size of the device, and at the same time, the reduction ratio of the screen radiated light is increased.
The D7 is being miniaturized. However, the condensing means 8 may be omitted if it is not desired to reduce the overall size of the device or the CCD 7.

The detection lens 17 having a larger aperture is more effective because it can capture a larger amount of screen radiation light. However, there is a drawback in that the larger the lens diameter, the larger the aberration and the more disturbed the image. Therefore, in the condensing means 8, the focusing plate 16 is provided at a position where the optical path length is the same as the optical path length of the liquid crystal panel 13 as viewed from the light-receiving / receiving lens 6, and the screen radiation light is once focused by the focusing plate 16. The image-forming light is scattered by the focusing screen 16 and transmitted, and then condensed by the detection lens 17 and guided to the CCD 7. By providing the focusing screen 16 between the detection lens 17 and the polarization beam splitter 5, the size of the detection lens 17 is reduced.

A Fresnel lens may be used instead of the focusing screen 16. The Fresnel lens has the characteristic that it can achieve the optical performance (especially the light utilization efficiency) equivalent to a large-diameter lens with a low-priced and small-sized one, and does not cause the same drawbacks (deterioration of aberration) as a large-diameter lens. If it becomes an effective optical means.

The image forming control section 9 comprises a display control circuit 18 for controlling the drive of the liquid crystal panel 13, a CCD control circuit 19 for controlling the drive of the CCD 7, and a signal processing circuit 20 including a microcomputer.

The signal processing circuit 20 comprises a table memory (not shown) for coordinate conversion and coordinate position correction, and the CCD control circuit 19 and the display control circuit 18 are provided.
The liquid crystal panel 13 and the CCD 7 are controlled via the. Further, the signal processing circuit 20 performs coordinate conversion of the bright spot position information signal detected by the CCD 7 and outputs the coordinate signal to the display control circuit 18. The display control circuit 18 is
A bright spot display image is formed based on the input bright spot coordinate signal, and the bright spot display image is combined with the projection image signal and output to the liquid crystal panel 13.

The positions of the bright spots on the projection screen A and the liquid crystal panel 13 are dependent on the aberrations of the light-receiving / receiving lens 6 and the detection lens 17, the mounting error of the projection screen A, and the like.
It is possible that the display position of does not match. Therefore, the signal processing circuit 20 corrects the coordinate signal so that the position of the bright spot on the projection screen A and the display position of the liquid crystal panel 13 coincide with each other.

Further, areas for designating various processing contents are set in the display area of the projection screen A, and the areas are recognized by the signal processing circuit 20 by designating these areas with the light pen 3. It is also possible to perform control such that processing is performed.

Reference numeral 21 in the drawing denotes a terminal device such as a keyboard and an external storage device connected to the signal processing circuit 20.

By the way, the reading frequency of the CCD 7 driven by the CCD control circuit 19 depends on the display control circuit 1.
Although the display frequency may be substantially the same as the display frequency of the liquid crystal panel 13 driven by the display panel 8, the read frequency is preferably set higher than the display frequency when higher accuracy is required. For example, if the display frame frequency is 6OH
In the case of z, if the reading frame frequency is 120 Hz, the position of the bright spot is detected for each frame, so the number of bright spot detection points is 120 points / sec.

The reason why the reading frequency is set high is as follows. That is, when performing image recognition by obtaining the position of the bright spot, the recognition rate increases as the number of detected frames per second increases. If the number of read frames is larger than the number of display frames, the coordinate detection accuracy is improved by calculating the average of the detected coordinate positions and using the average value as the detected coordinate.

FIG. 2 is a sectional view showing the structure of the light pen 3. The light pen 3 includes a power source 31, a control circuit 32, a light emitting element 33, and a micro switch 34 in a tapered cylindrical case 30 made of synthetic resin or the like.
The light emitting element 33 and the micro switch 34 are provided in the case 30.
The light of the light emitting element 33 is provided so as to face the transparent output window 35 provided at one end of the case 3 through the output window 35.
0 is output to the outside.

A through hole 36 is provided in the center of the output window 35, and a rod-shaped contact 37 is provided between the through hole 36 and the microswitch 34. One end 37a of the contactor 37 projects from the through hole 36 to the outside of the case 30, and the one end 37a is pressed to press the microswitch 34.
The light emitting element 33 is turned on and off by operating.

The light emitting element 33 is composed of an LED or a semiconductor laser and emits red light having a relatively long wavelength so that it can be easily seen, but the light emitting element 33 is not particularly limited to this. Any material that emits visible light may be used.

The light pen 3 is operated as follows.
That is, when the operator holds the contactor 37 in contact with the projection screen A, the microswitch 34 operates, and accordingly, the control circuit 32 turns on the light emitting element 33, and the output light from the output window 35. The light is transmitted and radiated to the outside of the case 30 to form a bright spot on the projection screen A. Note that the light pen 3 may be attached to the tip of a long indicator rod for use, and if so, a bright spot can be formed even on a part of the projection screen A that is out of reach.

When the operator or the like smokes in the vicinity of the projection screen A, there is a possibility that the cigarette light is erroneously detected as light from the light pen 3 on the side of the projection display apparatus main body 2. Such erroneous detection can be achieved by causing the light emitting element 33 to blink in a predetermined cycle by the control circuit 32.
The signal processing circuit 20 can distinguish the light of the light pen 3 and the light of the cigarette. However, in this case, in order to improve the identification accuracy, it is preferable to set the blinking period of the light emitting element 33 higher than the reading frame period of the CCD 7.

Further, another micro switch 38 may be provided on the outer peripheral portion of the case 30 of the light pen 3, and the light emitting element 33 may be turned on by operating the micro switch 38 with the operator's finger. . In this case, in the control circuit 32 and the like, the light emission by the operation of the micro switch 34 and the light emission by the operation of the micro switch 38 are distinguished by making the respective lighting frequencies different, for example. Then, when one of the micro switches (for example, the micro switch 34) is operated, the locus of the light pen 3 is displayed (the locus can be displayed on the projection screen A by the light pen 3). On the other hand, in the case of operating the other micro switch (for example, the micro switch 38),
It is possible to change the bright spot display such as not displaying the locus. In this way, the operator can distinguish between the display of characters and the like by the light pen 3 and the instruction on the projection screen A, and the operation becomes easier.

Next, the projection display operation by the projection display device 1 will be described.

The projection screen A is composed of an ordinary sheet of cloth, a white board, etc.
If the projection screen A cannot be prepared, it can be used on the wall surface. This projection screen A is installed in a conference room or the like. At this time, the projection screen A is arranged relative to the projection display apparatus main body 2 so that the surface of the projection screen A is orthogonal to the optical axis of the light-receiving / receiving lens 6. Then, the focal position of the light-receiving / receiving lens 6 is adjusted so that the display image on the liquid crystal panel 13 is formed on the projection screen A.

After performing such preparation work, the liquid crystal panel 13 is driven by the image formation control section 9 to form a display image on the liquid crystal panel 13, and the light source 1 for projecting light is also emitted.
2 is driven to emit light toward the liquid crystal panel 13.
Then, the image formed on the liquid crystal panel 13 becomes projection light and is output to the polarization beam splitter 5 side. The projection light is emitted as light polarized in a predetermined direction by the polarizing plate 15B provided on the liquid crystal panel 13. Since the polarization beam splitter 5 has a function of transmitting the projection light emitted from the liquid crystal panel 13 as described above, the projection light passes through the polarization beam splitter 5 and also serves as the light-receiving / receiving lens 6
Reach Then, the projection light that has reached the light-receiving / receiving lens 6 is condensed here and is enlarged and displayed on the projection screen A.

Here, with respect to the display image projected on the projection screen A by the operator, the light emitting element 33 of the light pen 3 is displayed.
When is operated in a state where is turned on, both the light of the display image on the projection screen A and the light of the bright spot by the light pen 3 are reflected by the projection screen A and become the screen radiation light, which is directed to the light-receiving / receiving lens 6.

When the cloth-made projection screen A is used, the light pen 3 may be operated on the back side of the projection screen A, which is the opposite side of the projection display apparatus main body 2. In this case, the light at the bright spot passes through the projection screen A, and then, together with the screen-reflected light of the projection light, forms the screen radiation light and travels to the dual-use lens 6 for light reception and reception. In this way, the screen radiation light radiated from the projection screen A is condensed by the lens 6 for both light transmission and reception and reaches the polarization beam splitter 5.

As for the polarization direction of the projection light reflected by the projection screen A, although some light changes its polarization direction at the time of reflection,
Most are aligned in the same direction as the polarization direction of the projected light. Therefore, of the screen radiation light that has reached the polarization beam splitter 5, most of the reflected light component of the projection light passes through the polarization beam splitter 5. On the other hand, since the light generated by the light pen 3 includes light in all polarization directions, most of the bright spot components in the screen radiation light are reflected by the polarization beam splitter 5. The bright spot component of the screen-reflected light reflected by the polarization beam splitter 5 forms an image on the focusing screen 16 arranged at the same optical path length position as the liquid crystal panel 13, and then is transmitted and scattered to form the detection lens 17
The image is again formed on the CCD 7 by.

The CCD 7 sends a bright spot position signal corresponding to the imaged light to the signal processing circuit 20 via the CCD control circuit 19. The signal processing circuit 20 determines the position with the highest brightness as the position of the bright spot by the light pen 3 based on the input bright spot position signal. Then, based on the determined bright spot position information, the display control circuit 18 creates a bright spot composite image, which is a composite of the bright spot display image and the image, on the liquid crystal panel 13 and projects and displays it on the projection screen A.

The bright spot input position by the light pen 3 is determined by the relative relationship with the position of the image projected on the projection screen A, and it is necessary to match the relative positions of both when displaying the bright spot. Therefore, in the projection display device 1, a single lens 6 for transmitting and receiving light serves both as a lens for focusing the projection light of the liquid crystal panel 13 and a lens for condensing the screen radiation light of the projection screen A. With such a configuration, even if the relative positional relationship between the projection display apparatus main body 2 and the projection screen A changes during the operation, the positional relationship between the bright spot display position and the image display position is prevented from varying, and The continuity of dot display and image display is always secured.

By the way, the liquid crystal panel 13 may be of a single color, but in the case of performing color display, it is necessary to use two pixels for each surface element.
A liquid crystal panel provided with filters of three colors, R (red), G (green), and B (blue) may be used.

In the above embodiment, a single liquid crystal panel 1 is used.
Although the projection display is performed by using the display No. 3, it is needless to say that the present invention can be applied to a projection display device that performs high-intensity color display using a plurality of liquid crystal panels, a dichroic mirror, and a total reflection mirror. .

Furthermore, as the light pen 3, FIG.
The configuration is not limited to that shown in FIG. For example, if a convex lens is provided in front of the light emitting element 33 and the focal position of this convex lens and the light emitting point of the light emitting element 33 are matched,
The emitted light can be collimated light. Light pen 3
With this configuration, even if the light pen 3 is operated at a certain distance from the projection screen A, the projection screen A
It becomes possible to form a bright spot on the top.

In the projection display device 1, the polarizing plate 15B
There is a structural feature that the cost can be reduced and the device can be downsized by omitting. This will be described below.

In the image projection operation of the liquid crystal panel 13, the polarization beam splitter 5 performs the same polarization operation as the polarizing plate 15B of the liquid crystal panel 13. That is, the polarization beam splitter 5 performs an operation of transmitting only light having the same direction as the polarization direction of the polarizing plate 15B. Therefore, regarding the image projection operation of the liquid crystal panel 13, either one of the polarization plate 15B and the polarization beam splitter 5 can be omitted. On the other hand, in the bright spot position detecting operation, the polarizing plate beam splitter 5 is a necessary component, but the polarizing plate 15B is completely unnecessary.

For these reasons, in the projection display device 1, the second polarizing plate 15B can be eliminated, and the cost of the material and the bonding step can be omitted, and the cost can be reduced accordingly. Furthermore, by omitting one polarizing plate, the utilization efficiency of projection light can be increased and the brightness of the display image on the projection screen can be increased.

Further, in the above embodiment, the light emitted from the light pen 3 is merely visible light, but it may be as follows. That is, if the light pen 3 is one in which the polarization direction of the emitted light is random, the component ratio of the emitted light reflected by the polarization beam splitter 5 in the emitted light of the light pen 3 becomes high, and the detection is performed. The accuracy increases.

Further, when the light pen 3 that outputs the circularly polarized emission light is used, the light component reflected by the polarization beam splitter 5 is surely present in the emission light of the light pen 3. This further increases the detection accuracy.

In the projection display device 1 described above, the polarization beam splitter 5 emits light parallel to the polarization direction of the polarizing plate 15B constituting the liquid crystal panel 13, that is, the polarizing plate 15
Although the light having the polarization direction orthogonal to the polarization direction of A is transmitted, the polarization beam splitter 5 may be configured as follows. That is, the polarization beam splitter 5
In addition, while eliminating the polarizing plate 15B constituting the liquid crystal panel 19, while transmitting light having a polarization direction orthogonal to the polarization direction of the polarizing plate 15B (light having a polarization direction parallel to the polarization direction of the polarizing plate 15A), Light having a polarization direction parallel to the polarization direction of the polarizing plate 15B (light having a polarization direction orthogonal to the polarization direction of the polarizing plate 15A) may be reflected. Even with such a configuration, only the display is inverted on the projection screen A and the basic operation is not affected.

Furthermore, in the projection display device 1 described above,
The polarization beam splitter 5 transmits the projection light of the liquid crystal panel 13 while reflecting the component of the screen radiation light whose polarization direction is orthogonal to the projection light of the liquid crystal panel 13 to separate the bright spot component from the screen radiation light. However, the present invention is not limited to this, and may be configured as follows. That is, the liquid crystal panel 1 with the polarization beam splitter 5
While the projection light of No. 3 is reflected, the bright spot component is separated from the screen radiation by transmitting the component of the screen radiation whose polarization direction is orthogonal to the projection of the liquid crystal panel 13. In this case, the arrangement position of the liquid crystal panel 13 and the arrangement position of the CCD 7 need to be opposite with respect to the polarization beam splitter 5, but even with this configuration, the basic operation is affected. There is no such thing.

[0070]

As described above, according to the present invention, the following effects can be obtained.

Effect of Claim 1 The image forming operation can be performed together by the image forming means without separately performing the image forming operation of the projection light and the condensing operation of the screen radiation light. Therefore, regardless of the positional accuracy of the projection screen, there is no change in the relative positional relationship between the projection light that has performed the imaging operation and the screen emission light that has performed the focusing operation, and a bright spot with high accuracy can be obtained. You can now display.

Further, by separating the bright spot components according to the polarization direction, it becomes possible to form bright spots by visible light. Therefore, it is possible to visually confirm the position of the bright spot on the projection screen, and it becomes possible to reliably form the bright spot, and it is necessary to separately provide the bright spot projecting means with the visible light emitting means. As a result, no extra parts are needed and the cost is reduced.

Effect of Claim 2 Since the screen radiation light is separated by the polarization beam splitter, the separation accuracy is increased, and the certainty of bright spot detection is increased accordingly.

The effect of claim 3 The reduction ratio of the bright spot component of the screen radiated light is increased, and accordingly, the structure of the bright spot position detecting means can be downsized, and the cost can be reduced accordingly.

Effect of Claim 4 In the screen radiated light, the light component reflected by the optical means is surely present, and the precision of the position detection of the bright spot is further improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a projection display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a light pen that constitutes the projection display device of the embodiment.

FIG. 3 is a diagram showing a configuration of a first conventional example.

FIG. 4 is a diagram showing a configuration of a second conventional example.

FIG. 5 is a diagram showing a configuration of a third conventional example.

[Explanation of symbols]

 5 Polarization beam splitter 6 Lens for both light transmission and reception 13 Liquid crystal panel

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 5/74 H04N 5/74 Z

Claims (4)

[Claims] 1. An image forming unit for outputting projection light of an image created by the liquid crystal panel to a projection screen by transmitting light to the liquid crystal panel, and forming the projection light on the projection screen. on the other hand,
An image forming means for collecting screen radiation light reflected or transmitted through the projection screen; a bright spot projection means for projecting a bright spot of visible light on the projection screen; and the image forming means and the image forming means. Provided between
From the screen emission light or the projection light, an optical means for separating a projection light reflection component of the screen emission light or a bright spot component having a polarization direction different from that of the projection light, and the brightness of the screen emission light separated by the optical means Bright spot position detecting means for detecting the position of the point component, and bright spot display image forming means for causing the image forming means to create a bright spot display image based on the bright spot position information detected by the bright spot position detecting means A projection display device comprising: 2. A polarization beam splitter which separates a projection light reflection component and projection light of screen radiation light and a bright spot component of screen radiation light according to a difference in polarization direction, reflects one and transmits the other from the polarization beam splitter. The projection display device according to claim 1, wherein the projection display device comprises means. 3. The projection display according to claim 1, further comprising a condensing unit that condenses a luminescent spot component of screen radiated light between the optical unit and the luminescent spot position detecting unit. apparatus. 4. The projection display device according to claim 1, wherein the bright spot projection means projects a bright spot made of light in a circularly polarized state.