Image display apparatus and method for compensating display...

Computer graphics processing and selective visual display system – Plural physical display element control system – Optical means interposed in viewing path

Reexamination Certificate

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Details

C345S207000

Reexamination Certificate

active

06628248

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image display apparatus that displays images by projecting a light modulated and emitted from a light source on a screen.
2. Description of the Related Art
In recent years, along with the enrichment of image equipment such as a video tape recorder, a video disc player and video software, there has been a growing demand for a large screen image display apparatus to enjoy images with more impact. As a conventional large screen image display apparatus, there is an image display apparatus that projects images on a screen or the like by using a liquid crystal panel for the image display part and spatially modulating the light emitted from a light source with the light crystal panel.
FIG. 13
is a configuration diagram showing an example of a conventional image display apparatus using a liquid crystal panel for the image display part.
In
FIG. 13
, after a light emitted from a lamp
101
serving as a light source and a reflected light reflected by a reflector
102
are focused on a focusing lens
103
, the light is decomposed into three primary colors of red, green and blue by color separating dichroic mirrors
104
,
105
. Each primary color is led by a red liquid crystal panel
112
, a green liquid crystal panel
113
and a blue liquid crystal panel
114
, and after the colors are composed by a color composition prism
115
, they are projected on a screen
117
by a projection lens
116
. Furthermore, total reflection mirrors
106
,
107
,
108
are provided to change the optical path of the light beam, and lenses
109
,
110
,
111
are provided to adjust the angle of the light beam entering each liquid crystal panel. With respect to the lamp used as the light source, white light sources such as a discharge-type extra-high pressure mercury lamp, a metal halide lamp or a thermoluminescence-type halogen lamp are used.
The red liquid crystal panel
112
, the green liquid crystal panel
113
and the blue liquid crystal panel
114
are driven by a red picture signal, a green picture signal and a blue picture signal respectively. The light emitted from the lamp
101
is modulated spatially when passing through each liquid crystal panel and projected as images on the screen
117
by the projection lens
116
.
In the above-mentioned conventional configuration, the images are displayed by driving the liquid crystal panels with the picture signals and changing the transmittance of the light by the liquid crystal panels. However, since the light blocking performance of the liquid crystal panels is not perfect, the display performance in low gray scale images was bad, so that it was difficult to obtain high-quality images. Furthermore, most of the lamps used at present have low light utilization efficiency, which is a ratio of emitted light in proportion to introduced electricity, so that high-intensity lamps must be used to obtain bright projected images. Therefore, there was a problem in that the power consumption increased, and that the heating from the lamp also rose.
To solve these problems, an image display apparatus, which is characterized by having light-emitting means including a plurality of self-emitting elements radiating respectively in red, green and blue according to an electric picture signal corresponding to information of images to be displayed, beam scanning means for scanning the light emitted from the light-emitting means in an arbitrary direction, and image formation means for forming the light emitted from the light-emitting means into images on a screen, is proposed.
However, although the conventional problems are solved with the image display apparatus in which a plurality of self-emitting elements are arranged as described above, due to the fact that a plurality of self-emitting elements are used for each color, the variance of emission luminance characteristics of each of the self-emitting elements caused the problem of increasing unevenness in luminance or in color for the images projected on the screen.
SUMMARY OF THE INVENTION
In order to achieve the aforementioned object, an image display apparatus of the present invention comprises light-emitting means including a plurality of light-emitting elements that modulate an intensity of a self-emitting light radiating respectively in red, green and blue according to an electric picture signal corresponding to information of images to be displayed, the light-emitting elements being arranged in a line according to each color,
focusing means for focusing the light emitted from the light-emitting means,
projection means for enlarging and projecting the light focused by the focusing means,
beam scanning means for scanning the light projected by the projection means on a screen by a beam scanning means driving circuit, to which an output signal is input from a synchronous processing circuit, a synchronous signal being input from outside to the synchronous processing circuit,
photodetector means having at least one photodetector element for receiving the light emitted from the light-emitting means,
a comparator for comparing the individual intensity of the light, to which an intensity of the light received by the photodetector means is input on one side, and to which an intensity of a light serving as reference is input on the other side,
a correction circuit for correcting an output signal from an image circuit, to which a picture signal synchronized with the synchronous signal based on the result of the comparator is input, and
a light-emitting means driving circuit for driving the light-emitting means, to which an output from the correction circuit is input. According to the image display apparatus described above, the variance in the emission luminance characteristics can be corrected, and luminance unevenness of images projected on a screen can be prevented from occurring.
In the aforementioned image display apparatus, it is preferable that the photodetector means is positioned outside an effective image area of the screen and receives the light scanned by the beam scanning means. According to the image display apparatus described above, the photodetector means does not block the screen, so that it is not necessary to move the photodetector means in both cases of displaying images and receiving light. Thus, the task of adjusting luminance unevenness is simplified.
Furthermore, it is preferable that the photodetector means includes a plurality of photodetector elements arranged in lines, and that each of the photodetector elements receives a light for one set of red, green and blue light-emitting elements of the light-emitting means. According to the image display apparatus described above, the cost and the number of man-hours can be reduced compared to the case of arranging a photodetector element for each light-emitting element.
Furthermore, it is preferable that light-emitting elements other than the light-emitting element involved in the light for one set do not emit light when receiving the light for the one set. According to the image display apparatus described above, the other light-emitting elements are not affected by the light, so that the deterioration of detection accuracy can be prevented.
Furthermore, it is preferable that the photodetector element receives light from plural sets of the light-emitting elements simultaneously by allowing one set of the light-emitting elements located in portions separated at a predetermined distance to emit light. According to the image display apparatus described above, the detection time can be reduced while preventing the detection accuracy from deteriorating.
Furthermore, it is preferable to provide a control circuit for controlling the beam scanning means driving circuit, to which an arbitrary detection signal is input. According to the image display apparatus described above, it is possible to correct luminance unevenness at any time.
Furthermore, it is preferable that the control circuit is a circuit that controls the beam scanning means driving circuit such that the light enl

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