Projection type image display device

Abstract

In accordance with distribution information such as the maximum, minimum, average or histogram of an input video signal, a stop control angle calculating unit (2) calculates a stop control angle for controlling the quantity of light to reach a display device (10) from a lamp (6), and inputs the same as control angle information to a fan control signal generating unit (3) and a stop drive unit (8). On the basis of the control angle information, the stop drive unit (8) controls the angle of a stop (9). The light of the lamp (6), as driven by a lamp drive unit (5), enters the stop (9) so that it goes in a quantity matching the angle of the stop (9) into the display device (10). The fan control signal generating unit (3) controls the speed of a cooling fan (4) in accordance with the control angle information and a temperature detected by a temperature sensor. Thus, the display image can be given a high contrast while suppressing the noise due to the rise in the speed of the cooling fan and avoiding the influences of the temperature to retain the reliability of the lamp.

Description

field of invention [0001] The present invention relates to a projection-type image display device such as a projector, and more particularly, to a projection-type image display device configured to obtain a high-contrast display image by controlling the amount of light incident on the display device by a diaphragm. Background technique [0002] As a projection display device or a direct-view liquid crystal display device, the light emitted from a light source (hereinafter referred to as a lamp) is spatially modulated by a display device having a transmissive or reflective light modulation function to display an image. Image display devices are well known. In an image display device using such a display device having a light modulation function, when compared with an image display device using a self-luminous display device such as a CRT, so-called blackness in dark places has been a problem. The so-called black is not black refers to the phenomenon that the pixels displayed...

AI Technical Summary

Problems solved by technology

[0010] However, there is the following technical problem: when the light quantity of the lamp is increased according to the above-mentioned requirements, or when the aperture is fully closed, the return light reflected from the aperture increases, causing light damage to peripheral components such as the lamp and the fixing fixture. heat damage

[0012] In addition, the conventional method measures the temperature near the lamp, so the temperature of the bulb (bulb) itself of the lamp which becomes high temperature cannot be accurately measured.

[0013] Therefore, there is a problem that in order to ensure the reliability of the lamp, it is necessary to consider the margin of the cooling capacity, and the rotation speed of the cooling fan is also increased, and the noise is also increased.

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