Picture display method and apparatus

Abstract

A picture display method and apparatus in which a light source is lengthened in service life and optimum color reproduction is realized, while the light utilization efficiency is improved to reduce the power consumption and the size of the apparatus. The red, green and blue illuminating light beams radiated from the light-emitting diodes 12R, 12G and 12R, are illuminated via relay lenses and field lenses on picture display light bulbs 11R, 11G and 11B and spatially modulated in intensity so as to be synthesized by a synthesis prism 10 and so as to be projected to an enlarged scale on a screen 17. The profile of the light radiating portions of the light-emitting diodes 12R, 12G and 12B are set so as to be the same or similar to the profile of a picture display area of each of the picture display light bulbs 11R, 11G and 11B in order that the profile of the light beam illuminated on the picture display area will be in keeping with the profile of the picture display area.

Description

[0001] 1. Field of the Invention[0002] This invention relates to a picture display method and apparatus for displaying a picture by spatially modulating the light outgoing from a light source and projecting the modulated light.[0003] 2. Description of the Related Art[0004] Among picture display apparatus used for the purpose of appreciating a picture, there is a projection type picture display apparatus in which the light outgoing from a light source is spatially modulated by a picture display light bulb for projection on a screen. This projection type picture display apparatus is classified into a front side projection type in which the picture is projected from the front side, such as a screen, and a back side projection type in which the picture is projected from the back side of the screen. As this projection type picture display apparatus, there is known such apparatus in which a white light source, including a discharge type xenon lamp, a metal halide lamp or a heat light emis...

AI Technical Summary

Problems solved by technology

The above-described conventional projection type picture display apparatus has a defect that, since the white light source (lamp), such as xenon lamp, metal halide lamp or halogen lamp, used as a light source, generally undergoes significant chronological changes, and is of short service life, the picture tends to become dark, while the lamp tends to be used up, such that the displayed picture tends to become dark or the lamp has to be exchanged during display of the picture.

The result is that much light is wasted to lower the utilization efficiency of light from the light source.

Moreover, the conventional projection type picture display apparatus has a defect that, because of the low utilization efficiency of light from the light source, a brighter light source needs to be used for obtaining the necessary brightness, and a defect that, since a larger light source needs to be used for realizing the necessary brightness, it becomes necessary to reduce the size of the projection type picture display apparatus.

The result is that the wavelength distribution of the separated colors depends on the wavelength distribution of the outgoing light of the original white light source to make difficult optimum color reproduction.

Moreover, in the white light source used in the conventional projection type picture display apparatus, brightness modulation is generally not possible or only narrow in brightness adjustment range, with the response time of brightness modulation being longer, such that, in the conventional projection type picture display apparatus, the displayed picture cannot be adjusted in brightness or can be adjusted only in a narrow range.

Also, if, in the conventional projection type picture display apparatus, the radiated light of the white light source is color-separated by, for example, a dichroic mirror so as to be illuminated on picture display light bulbs associated with respective color signals, it is difficult to adjust brightness of the light from one color to another.

Thus, with the conventional projection type picture display apparatus, fine color adjustment is difficult or can be realized only in a narrow range.

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