JP2007127781A - Projection display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display apparatus having a function of correcting white balance properly and automatically according to a state of a projection plane. <P>SOLUTION: The projection display apparatus projects an image on a screen, and comprises: a detection means for detecting the light reflected from the screen; a color temperature measuring means for measuring a color temperature of the light detected by the detection means; and a white balance compensation means for correcting the white balance of the light projected to the screen, and corrects the white balance of the light projected to the screen according to a change in the color temperature of the reflected light from the screen. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection display device having a function of automatically performing image correction, and more particularly to a projection display device having a function of automatically correcting white balance appropriately according to the state of a projection surface.

  Conventionally, as a technique for performing various corrections such as convergence, geometric distortion, luminance, focus, and white balance in a projection display device (front projector), there is one disclosed in Patent Document 1. The image correction apparatus described in Patent Document 1 reflects light projected from a projector lens onto a screen and makes it incident on an image pickup device such as a CCD camera sensor, and calculates error values of R, G, and B of the incident light. A correction signal for calculating and correcting this is output to the projector.

Japanese Patent Laid-Open No. 7-15692 (FIGS. 1, 3 and the like).

  However, there are various environments in which the projection display device is used. For example, the color of the image actually projected on the screen changes depending on the color and material of the screen, the lighting conditions (natural light and artificial light), and the like. . For example, the image on the screen tends to appear bluish under a fluorescent lamp, and tends to appear red under natural light. As described above, in the conventional projection display device, the projection type display device is actually used because it directly measures the light projected from the lens toward the screen and corrects white balance and the like. It is not possible to perform white balance correction adapted to the environment.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a projection display device having a function of automatically correcting white balance appropriately according to the state of the projection surface.

  As a result of diligent research in view of the above-mentioned problem, the inventor does not directly measure the projection light, but measures the reflected light from the screen, and the projection having an image correction function that performs white balance correction based on the measurement. A type display device is proposed.

  That is, the present invention is a projection-type display device that projects an image on a screen, a detection unit that detects reflected light from the screen, and a color temperature measurement unit that measures a color temperature of light detected by the detection unit And white balance correction means for correcting the white balance of the light projected onto the screen, and correcting the white balance of the light projected onto the screen according to a change in the color temperature of the reflected light from the screen. The present invention provides a projection type display device.

  The present invention is also a projection display device for projecting an image on a screen, the detecting means for detecting reflected light from the screen, and the color temperature measuring means for measuring the color temperature of the light detected by the detecting means. And white balance correction means for correcting the white balance of the light projected onto the screen, when the color temperature of the reflected light from the screen changes, the color temperature of the reflected light returns to the value before the change. As described above, the present invention provides a projection display device that corrects the white balance of light projected onto the screen.

  In the projection type display device of the present invention, when the light detected by the detection means is less than a certain brightness, the color temperature measurement means does not measure the color temperature. The detection means can be composed of a CCD camera sensor.

  The present invention is also a method for performing image correction in a projection display device that projects an image on a screen, the step of detecting reflected light from the screen, and measuring the color temperature of the light detected by the detecting means. And a step of correcting the white balance of the light projected onto the screen in accordance with a change in the color temperature of the reflected light from the screen.

  The present invention is also a method for performing image correction in a projection display device that projects an image on a screen, the step of detecting reflected light from the screen, and measuring the color temperature of the light detected by the detecting means. And correcting the white balance of the projection light on the screen so that the color temperature of the reflected light returns to the value before the change when the color temperature of the reflected light from the screen changes. An image correction method characterized by the above is provided.

  In the image correction method of the present invention, when the detected reflected light from the screen is less than a certain brightness, the color temperature of the reflected light is not measured. Detection of the reflected light from the screen can be performed by a CCD camera sensor built in or attached to the projection display device.

  As described above, according to the projection type display device of the present invention, a projection type display device having a function of automatically correcting white balance appropriately according to the state of the projection surface is provided.

  Hereinafter, the best mode for carrying out the projection display device of the present invention will be described in detail with reference to the accompanying drawings. 1 to 4 are diagrams illustrating embodiments of the present invention. In these drawings, the same reference numerals denote the same components, and the basic configuration and operation are the same. To do.

  FIG. 1 is a diagram schematically showing a usage form of a projection display device of the present invention. In FIG. 1, the projection type display device of the present invention can project an image onto an arbitrary screen from a projector projection lens. There are various usage environments at this time. For example, it may be used indoors under fluorescent lighting, or may be used under natural light. Also, the color and material of the screen can vary. In particular, in recent years, projection type display devices have become smaller and more mobile, and are often brought into various places for use.

  FIG. 2 is a diagram schematically showing an apparatus configuration for realizing the white balance automatic correction function in the projection display apparatus of the present invention. In FIG. 2, the projection display device adjusts the white balance of the captured image, a CCD camera sensor that receives the reflected light from the screen, a white balance detection unit that detects the white balance of the image captured by the CCD camera sensor. And a correction signal generation unit that generates a correction signal for the purpose. In FIG. 2, the CCD camera sensor, the white balance detection unit, and the correction signal generation unit are shown outside the projector main body, but these may be independent as an image correction device or integrated with the projector. It may be.

  FIG. 3 is a flowchart showing in detail the operation of automatically correcting white balance in the projection display apparatus of the present invention. In FIG. 3, first, when the projection display device is activated, the brightness is determined by the CCD camera sensor. When the brightness is sufficiently bright, the color temperature of light incident on the CCD camera sensor from the screen is measured, and initial values of various parameters in the CCD camera sensor are set based on the measurement result. If it is not bright enough, the above processing is omitted.

  Thereafter, when the illumination environment changes, such as by turning on a fluorescent lamp, the CCD camera sensor detects this change, and again measures the color temperature of light incident on the CCD camera sensor from the screen. Subsequently, the difference between the color temperature measured before lighting and the color temperature measured after lighting is calculated, and the white balance deviation caused by lighting is corrected. After the white balance correction, the color temperature of the light incident on the CCD camera sensor is measured again to confirm that the appropriate white balance correction has been performed, and the white balance automatic correction process is terminated. .

  The color temperature is a scale representing the relative intensity of bluish violet light and red light contained in light. The color temperature is higher for a bluish color and the color temperature is lower for a reddish color. As a specific method for measuring the color temperature, there is a method for calculating the color temperature from chromaticity coordinates obtained by integrating the color matching functions over the measurement object for each of the three colors R, G, and B of the incident light. .

  Here, a mechanism for correcting white balance based on the difference between the color temperature measured before lighting and the color temperature measured after lighting will be described with reference to FIG. FIG. 4 shows a graph in which the gains of R and B detected by the CCD camera sensor are each taken on two axes. The gain of G is fixed, and changes in the gains of R and B are observed. It is considered that the gains of R and B change along a certain line shown in the figure with respect to changes in various lighting environments. Therefore, the gains of R and B before lighting are stored, and compared with the gains of R and B detected after lighting, the gains of R and B return from the state after lighting to the state before lighting. It can be seen that by correcting the projector light source, it is possible to correct the white balance deviation caused by lighting.

  The projection display device of the present invention has the above-described white balance automatic correction function, so that it is possible to perform appropriate white balance correction according to the illumination environment and the screen when actually used. In particular, when lighting is turned on, the color temperature is measured and compared with the measured value of the color temperature before lighting, so that the white balance suitable for the lighting environment after lighting is corrected. There is an advantage that can be. The lighting is automatically detected by the CCD camera sensor, and all subsequent automatic white balance correction can be performed automatically, so that the user can adjust the lighting in the room freely as appropriate. Since the image correction is automatically performed, the user is not bothered by the image correction.

  As described above, the projection type display device of the present invention has been described with reference to specific embodiments, but the present invention is not limited thereto. A person skilled in the art can make various changes and improvements to the configurations and functions of the invention according to the above-described embodiments or other embodiments without departing from the gist of the present invention.

It is a figure which shows roughly the utilization form of the projection type display apparatus of this invention. It is a figure which shows roughly the apparatus structure for implement | achieving the white balance automatic correction function in the projection type display apparatus of this invention. 5 is a flowchart showing in detail an operation for automatically correcting white balance in the projection display device of the present invention. It is a figure which shows the mechanism which correct | amends white balance based on the difference of the color temperature measured before lighting, and the color temperature measured after lighting.

Claims (8)

A projection display device that projects an image on a screen,
Detecting means for detecting reflected light from the screen;
Color temperature measuring means for measuring the color temperature of the light detected by the detecting means;
White balance correction means for correcting the white balance of the light projected onto the screen,
A projection-type display device that corrects a white balance of light projected onto the screen in accordance with a change in color temperature of light reflected from the screen. A projection display device that projects an image on a screen,
Detecting means for detecting reflected light from the screen;
Color temperature measuring means for measuring the color temperature of the light detected by the detecting means;
White balance correction means for correcting the white balance of the light projected onto the screen,
When the color temperature of the reflected light from the screen changes, the white balance of the projected light on the screen is corrected so that the color temperature of the reflected light returns to the value before the change. apparatus.   3. The projection display device according to claim 1, wherein when the light detected by the detection unit is less than a certain brightness, the color temperature measurement unit does not measure the color temperature. 4.   The projection display device according to claim 1, wherein the detection unit includes a CCD camera sensor. A method of performing image correction in a projection display device that projects an image on a screen,
Detecting reflected light from the screen;
Measuring the color temperature of the light detected by the detection means;
Correcting the white balance of the light projected onto the screen in accordance with a change in the color temperature of the reflected light from the screen. A method of performing image correction in a projection display device that projects an image on a screen,
Detecting reflected light from the screen;
Measuring the color temperature of the light detected by the detection means;
Correcting the white balance of the projection light to the screen so that the color temperature of the reflected light returns to the value before the change when the color temperature of the reflected light from the screen changes. Image correction method.   The image correction method according to claim 5 or 6, wherein when the reflected light from the detected screen is less than a certain brightness, the color temperature of the reflected light is not measured.   The image correction method according to claim 5, wherein the detection of the reflected light from the screen is performed by a CCD camera sensor built in or attached to the projection display device.

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