JPS6193789A - Automatic convergence device - Google Patents

Abstract

PURPOSE:To detect automatically misconvergence of plural projecting tubes by projecting the light incident on a main screen to a sub-screen via a reflecting mirror and picking up the video image of the sub-screen by an image pickup device. CONSTITUTION:A projector PJ consists of red, green, blue projection tubes 10 at the back side of the main screen 1 and the video image is projected on the main screen 1. A detection unit 2 is arranged near the back side of the main screen 1 and consists of a reflecting mirror 3, the sub-screen 4 and video cameras 5X, 5Y. The relative position of the projector PJ, the reflecting mirror 3, the sub screen 4 and the main screen 1 is set so that the optical path length from the projection tube 10 in the unit 2 t the sub screen 4 via the reflection mirror 3 is equal to the optical path length D between the projection tube 10 and the main screen 1. That is, the convergence shift (f) on the main screen 1 and a convergence shift f' on the sub screen 4 are selected equally.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an automatic convergence device that automatically controls and adjusts the convergence of a large screen system that projects images onto a large screen (hereinafter referred to as the main screen) using a plurality of projection tubes. Regarding the number.

Conventional Technology Conventionally, when projecting an image onto a screen using one or more sets of projection tubes that emit light in the three primary colors of red, green, and blue, convergence adjustment is performed to match the position of the image from each projection tube. As a method, for example, as shown in FIG. 7, a color image on a screen is detected by an imaging device such as a video camera, and the amount of positional deviation, that is, convergence deviation, of each primary color image of the color image is calculated and a correction signal is generated. A method of controlling and automatically adjusting the convergence circuit of each projection tube is proposed in Japanese Patent Publication No. 5B-40390.

Problems to be Solved by the Invention However, in this conventional method, when the projected screen is extremely large, the brightness of the projected image becomes low.

Imaging devices have limited sensitivity, and it is impossible to detect each color of a color image on a screen using imaging KH. As a means to solve this problem, for example, as shown in FIG. 8, a method can be considered in which a plurality of sets of imaging devices (video cameras in the figure) are arranged in close proximity to the front of the screen to detect low-luminance images on the screen.

However, in this case, in the method of detecting color images on the screen by arranging multiple sets of video cameras in front of the screen, that is, on the viewer's side, the group of video cameras is placed in front of the screen only when adjusting convergence. During normal viewing, it is necessary to move this group of video cameras from the front of the screen to the outside of the screen.

In particular, if there is no space to house a group of video cameras on the left and right sides of the screen, or on the top and bottom sides, the method shown in FIG. 8 cannot be carried out.

In addition, if the front side of the screen, that is, the viewer side, is in the form of a theater, the mechanism for moving the camera group to the front of the screen will spoil the aesthetics), and this method cannot be implemented because it is not very practical. There is.

In addition, although the conventional embodiment shown in the ti7 and m8 diagrams shows a rear projection method in which the screen is projected from the back and viewed from the front, convergence detection is also possible in the front projection method in which the projector is placed in front of the screen. Equipment constraints arise. That is, even in the front projection system, if the screen is large and the brightness of the image is low, it is impossible to detect a convergence shift with the image carrier, as in the conventional example shown in FIG. In particular, the method of arranging a plurality of video cameras as shown in FIG. 8 has the disadvantage that the mechanism for adjusting the position and orientation of the video cameras so as not to obstruct the optical path incident on the screen is complicated.

Means for Solving the Problems The present invention provides a large screen projection system that projects images onto a large main screen using a projector consisting of a plurality of projection tubes, in which a convergence detection device is disposed between the main screen and the projector. The convergence detection device is formed of one or more sets of a reflecting mirror, a sub-screen, and an image sensor, and projects the light incident on the main screen onto the sub-screen via the reflecting mirror, so that the image on the sub-screen is projected onto the sub-screen. The gist of the present invention is to detect a convergence shift of the plurality of projection tubes by photographing with an ia device, and to control a convergence circuit of the projector.

In a large screen projection system, a convergence detection device can be placed in the optical path of the projection light, so even if the brightness of a bright spot is extremely low, convergence can be corrected without any problem.

Embodiment An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, PJ is a projector composed of red, green, and blue projection tubes IO that projects images onto the main screen l from the back side of the main screen l. 2 is a detector unit placed close to the back of the main screen 1, and is composed of a reflector 3, a sub-screen ↓, and video cameras 5X and 5Y. The detection unit 2 projects the optical path length from the projection tube 10 to the sub-screen 4 via the reflection ri3, and projects it so that it is equal to the optical path length between the tube 10 and the main screen 1 @PJ, reflecting mirror 3.
, the subscreen IJ+74, and the main screen 1 are set relative to each other. That is, the convergence shift f on the main screen/1 and the convergence shift f' on the sub-screen are selected to be equal. Detection unit 2
An example of the structure is shown in FIG. In this embodiment, two video cameras are used, and the camera 5X detects the position in the horizontal direction corresponding to the brightness outside the screen, and the camera 5Y detects the position in the vertical direction. The image reflected by the reflecting mirror 3 and projected onto the sub-screen is viewed by a camera 5x and a camera 5Y.

For example, a dot pattern signal is applied to the projection unit PJ and projected. Then, adjust the convergence adjustment point at the top of the screen as shown in Figure 5.

There are m locations in the downward direction and n locations in the left and right direction. m sets of detection units 2 shown in FIG. 2 are arranged in the vertical direction of the main screen l to form a convergence detection unit group 6, which is moved in the left-right direction. FIG. 3 shows a specific example of the structure to be moved. Rails 7 are arranged parallel to the main screen 1 above and below the main screen 1, and a convergence detection unit group 6 is driven by a servo motor 8.

When the convergence detection unit group 6 stops in the left and right direction of the main screen, for example, at the first position, the cameras 5
Then, bright spots on each sub-screen 74 are detected. - The projection tubes for 10,000 tickets, green, and blue are switched sequentially to emit light. Each bright spot is detected on the time axis of the electrical signal from the video cameras 5X, 5'/. An example of the signal processing circuit is shown in FIG. In Fig. 4, each detection unit 2 is equipped with two cameras 5X, 5"/, but each camera 5X
, 5Y receives the synchronization signal supplied from the synchronization clock generator 16 generated from the clock signal, and photographs the bright spot on the sub-screen 4, and the ! The video signal of the pulse bark shown in Fig. 6 is extracted. The switcher 11 is a camera that detects the positions of the m detection units 2 in the vertical direction and in the vertical direction and the horizontal direction on the sub-screen ↓, with each detection unit 2 as one unit for each 1st to mth address. 5
The output of the video signal is switched for each X and camera 5Y. The camera output signal selected by the switcher 11 is given to the n-point position detection circuit 12. Here, the output signal of the camera passes through the amplifier 13 to detect the peak value, and further passes through the time axis detector 13 to detect the time difference tχ between the synchronization signal and the pulsed video signal for the video signal as shown in FIG. Ru. This signal is transferred to memory 17 by system controller 15. In this way, the measuring device tRs on the time axis of the pulse position corresponding to each color of red, green, and blue.
tGs tB is stored in memory 17. It should be noted that the memory 17 stores measurement values of type 6!1 when two projection tubes 10 are used each for red, green, and blue.

Next, for example, based on the measured value tG of the green projection tube, tR,
The time difference (tG-tR) and (tG-tB) of tB are calculated, and a correction signal corresponding to the time difference is added to the convergence circuit for each projection tube to control the time difference (tG-tx)=O.

Note that the calculation of the time difference may be performed at once after measuring all adjustment points mXn on the screen. m
The detection unit group of the set is the first detection unit group in the left and right direction of the main screen 1.
When the measurement is completed at the second position, the drive unit 19 is actuated via the controller 18 to move to the second position, and the position of the bright spot corresponding to the camera 5X, 5Y is set at the adjustment point 1 to m in the vertical direction. Measure. From now on, repeat this one by one.
When the time difference of the bright spot with respect to the reference projection tube is completed for each mXn address, for example, (tG-tx
) is calculated and stored in memory. Finally, a correction signal is generated from the system controller 15 and applied to the f/nosense circuit 20 to automatically adjust the convergence due to projection IJPJ.

Effects of the Invention As described above, according to the present invention, in a large screen projection system where the brightness of a bright spot on the screen is extremely low, automatic convergence adjustment can be performed by disposing a convergence detection device in the optical path of projection. I can do it. In the case of a large screen projection system for the D1 field using a rear projection method, the mechanism of the convergence detection device is not shown to the audience (viewers).
It becomes possible to remove defects that spoil the aesthetic appearance.Also,
According to the present invention, convergence adjustment can be performed in a short time even when a large number of projection tubes, such as 6 or 12, are used to project a large screen. Further, according to the present invention, there is no need to visually evaluate the convergence shift even on a large screen with a height of several meters (it can be used for extremely high precision measurement).

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing one embodiment of the present invention, Fig. 2 is a schematic enlarged view showing the main parts of this embodiment, and Fig. 3 is a front view of the embodiment shown in Fig. 1 as seen from the screen 1 side. , FIG. 4 is a circuit diagram according to the present invention, FIG. 5 is a dot pattern diagram used in the present invention, FIG. 6 is a waveform diagram for explaining the present invention in detail, and FIG.
8 and 8 are schematic diagrams showing a conventional example. l...Main screen, 2...Detection unit, 3...
・Reflector, 4. Fist, sub-screen, 5... Imaging device,
6... Convergence detection device, PJ/kai/projector.

Claims (1)

[Claims] In a large screen projection system that projects images onto a large main screen using a projector consisting of a plurality of projection tubes, a convergence detection device is disposed between the main screen and the projector, and the convergence detection device includes one or more sets. a set of reflectors, a sub-screen, and an imaging device, projecting light incident on the main screen onto the sub-screen via the reflector and photographing an image of the sub-screen with the imaging device; An automatic convergence device that detects a convergence shift of a projection tube and controls a convergence circuit of the projector.