JP2003324670A - Projection type video display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable a front projector to output a gradation image suitable for a screen and its surroundings. SOLUTION: The brightness (brightness) of the screen and its surroundings
, And sets the gradation of the projector output according to the measurement result. Specifically, by changing the setting of the brightness and the setting of the gamma, an appropriate gradation expression is always obtained. The most ideal setting can be obtained by measuring the brightness (brightness) of the above three points, that is, the bright and dark portions on the screen, and the periphery of the screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of image quality performance of a front projection type display device (front projector).

[0002]

2. Description of the Related Art Conventionally, a front projection type display device (hereinafter referred to as a projector) is provided with a function that allows a user to select a gamma setting or a projection light amount setting for a display image from a predetermined set value according to the purpose or to make the variable. There was a product to have. For example, for the gamma setting, "standard mode",
It has a function to change to the optimum gamma setting according to the input image such as "Cinema mode", and regarding the projection light amount setting, "Cinema mode", " There was also a mode called "eco mode" that reduced the amount of light.

A block diagram of a typical configuration of the prior art is shown in FIG. 6 for explanation.

A video input circuit 11 receives a video signal of 11i and converts it into a digital signal of a predetermined format. The output signal is then converted into a signal having an image size (for example, XGA = 1024 × 768) and a refresh rate matched with the pixel configuration of the display element (3) such as an LCD by the 12 resolution conversion circuits. Next, it is corrected to an appropriate gamma characteristic by the gamma setting circuit 13 and the next 14
Is supplied to the display element drive circuit. Finally, it is supplied to the third display element, and the distribution of light transmittance is formed to create a two-dimensional image.

The control of the 13 gamma setting circuit is performed by 16 controllers (generally constituted by microcomputers), and this controller loads predetermined values into the register table in the gamma setting circuit. Has been realized.

For example, by loading any one of the four gamma characteristics shown in FIG. 2c, the setting can be instantaneously switched.

On the other hand, the light required for projection is first generated by the five light sources. The light is evenly applied to the display area of 3 by the illumination optical system of 4A, and a light flux according to the transmittance distribution of 3 is generated by the projection optical system of 4B to form a light flux 7A that is imaged on a plane at a predetermined distance. It is projected on a screen (not shown).

The light source 5 has its power supply controlled by a light source driving circuit 15 (generally called a ballast).
Although it functions to output a stable light amount, it is possible to change the light amount of the light source in multiple stages depending on the control method.

The control of the light source driving circuit of 15 is also performed by the controller of 16, and the light quantity control of two steps, or several steps in some cases is possible by digital setting.

In the conventional example, 19 operation panels are connected to 16 controllers, and by this operation, one can set gamma and the other can set light intensity of the light source. ing.

[0011]

However, even if such functions are installed, a general user cannot effectively use these functions, and improper settings may cause uncomfortable images to be viewed. There are many situations in which they are doing so.

Regarding the setting of brightness and gamma,
It requires detailed knowledge of the characteristics of the human eye, and it is often the case that the video output was not adequate if the settings that seemed to be the best were just made.

In particular, the brightness and gamma settings are very important for obtaining the best image in viewing a cinema, and the combination with the environment of the theater room (wall color and density, lighting conditions) and the screen used. There are some things to consider.

Imagine, for example, a theater in a commercial movie theater. The theater gets quite dark when the movie starts. The brightness of the screen is neither too dark nor too bright, and it maintains a moderate amount. On the other hand, the characteristics of the human eye show different sensitivity characteristics in dark and bright areas. Regarding gamma, an image with a large gamma value looks more natural in a dark place, and an image with a smaller gamma value in a bright place. It is said that it looks more natural.

[0015]

The present invention focuses on the settings of brightness and gamma, considers both the brightness on the screen and the brightness around the screen for brightness, and for gamma, each brightness By providing an optimum viewing environment by automatically selecting the optimum setting according to the relationship of

Specifically, firstly, a means for measuring the brightness of the screen is provided, and in order to measure the gradation that can be expressed on the screen, a black image and a white image are projected and the amount of return light ( Second, it has a means to measure the brightness of the screen), secondly the brightness of the surroundings outside the screen, to understand how the screen is in the viewer's field of view, and thirdly the final. Specifically, it has means for setting gradation on the screen, and provides an optimum gradation image to the viewer.

For example, when trying to watch a movie source under the same darkness as in a theater of a commercial movie theater,
By setting the brightness of the screen to the same value as that and setting the gamma to the same gamma value, it becomes possible to provide an image with the same settings as in a movie theater.

Further, for example, when an equivalent dark condition cannot be obtained, the projection light amount is increased to increase the brightness of the screen and the gamma value is decreased so that the condition is not suitable for watching a movie. , It is possible to apply the best correction.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a block diagram showing the basic configuration of the present invention.

A video input circuit 11 receives the video signal of 11i and converts it into a digital signal of a predetermined format. The output signal is then converted into a signal having an image size (for example, XGA = 1024 × 768) and a refresh rate according to the pixel configuration of the display element (3) such as LCD by the 12 resolution conversion circuit. Next, it is gamma-corrected by the gamma setting circuit 13 and is supplied to the next 14 display element driving circuits. Finally, it is supplied to the third display element, and the distribution of light transmittance is formed to create a two-dimensional image.

The control of the 13 gamma setting circuit is carried out by the 16 controller (generally composed of a microcomputer), which is realized by loading a predetermined numerical value into the register table in the gamma setting circuit. There is.

For example, by loading any one of the four gamma characteristics shown in FIG. 2c, the setting can be instantaneously switched.

On the other hand, the light required for projection is first generated by the five light sources. The light is evenly applied to the effective area of the display element 3 by the illumination optical system of 4A, and the light flux passing through the display element is further transformed by the projection optical system of 4B into a light flux 7A which forms an image on a plane at a predetermined distance. The image is projected on a screen (not shown) on the front of the projector.

The light source 5 has its lighting controlled by a light source driving circuit 15 (generally referred to as a ballast) and functions so as to output a stable light amount. It is possible to change with. The control of the 15 light source drive circuits is also performed by the 16 controller, and the light quantity control of two steps, and in some cases, several steps is possible by digital setting.

In the present embodiment, description will be made assuming that the light amount can be controlled in four steps of large, medium and small.

In the present invention, the following means is further added to exert the effect of the present invention. Reference numeral 61 is an optical sensor, the output of which is converted into a digital value by the A / D conversion circuit of 17 and input to the controller of 16.

The optical sensor shown here is divided into three,
Each of them measures the brightness of the central portion of the projection area, the outer peripheral portion of one projection area, and the outer peripheral portion of the other projection area.

FIG. 2a is a front view of the projector body (80). 4C is a projection lens, which is a part of the projection optical system of 4B. Reference numeral 62 denotes a light receiving window of the optical sensor, which is arranged near the projection lens.

In this embodiment, since it is arranged above the projection lens, a slight vertical parallax occurs,
It is possible to measure with a negligible difference in the left-right direction.

In FIG. 2b, the area in which this sensor is staring is shown. For the projected area of 81, 61C,
Three regions 61L and 61R are set. It corresponds to the central portion of the projection area, the outer peripheral portion of one projection area, and the outer peripheral portion of the other projection area.

Next, the processing sequence will be described with reference to the flowchart of FIG. There are three values to measure: E: peripheral brightness outside the projection area Cmin: black projection brightness within the projection area (near the center) (minimum light intensity) Cmax: white projection brightness within the projection area (near the center) (maximum light intensity) ) The order of measurement does not matter, but in the present embodiment, the following order is used.

The first thing to do is to set the light quantity to a predetermined value. Generally, it is desirable to set the maximum value.

Next, the average value of the measured values of the two sensors (61L, 61R) on both sides in the measurement of the brightness outside the projection area is set to E.

Next, the projection brightness of the black image in the projection area is measured and set as Cmin.

Next, the projection brightness of the white image in the projection area is measured and set as Cmax.

From the above three measured values, the optimum light amount is first determined, the optimum gamma is further determined, and the respective changing operations are carried out.

In this embodiment, the light amount setting is made in three steps (600,
800, 1000 lumens), gamma setting can be set in 4 steps, and the size of the projection screen is 3 to 4 100 inches and the gain is 0.9.

First, an example in the case of almost darkness: Since it is darkness, the measured value becomes a value such as E = 0.

Further, the value of Cmax = 92 cd / m ² is obtained, and the proper luminance of the movie theater (12 fL = about 41 cd /
The value is almost twice that of m ² ).

Therefore, as the optimum brightness, 600 lumens, which is close to one half of the maximum light quantity, is selected. 1
At a setting of 000 lumens you will feel dazzling.

Next, the gamma is set so that E is zero, so that the sensitivity characteristic of the human eye is in a dark place.
Gamma4, which is the maximum gamma value shown in, is selected.

Next, an example in which illumination light leaks to some extent: measured values are E = 5 cd / m ² , Cmin = 10 c
The values are d / m ² and Cmax = 100 cd / m ² .

This is a situation in a bedroom of a general household, where the curtain may be closed during the day.

Under these conditions, the maximum light amount is 100
0 lumen is considered the optimal setting.

Further, since the sensitivity characteristic of the human eye is close to that in a bright situation, the optimum gamma is set to 1 and Gamma1 in FIG. 2c is selected.

[Second Embodiment] In the first embodiment,
As a means of controlling the maximum light amount, the light emission amount of the lamp is set
Although a method of selecting from among 00, 800, and 600 lumens has been shown, a method of controlling the light flux itself using a mechanical diaphragm means will be described here.

FIG. 3a shows diaphragm means (4D) having the same mechanism as that used in a video movie camera or the like, which is composed of a diaphragm blade and a galvanometer with an angle encoder. Although the one shown in the figure has a mechanism called a so-called iris diaphragm, other types may be used as long as the aperture area can be changed. The operation is to drive the aperture blades by changing the aperture area by supplying a drive current to the drive coil of the galvanometer. By incorporating this diaphragm means in the afocal part of the 4B projection lens, it becomes possible to control the projected light flux amount (7A) in multiple stages.

The amount of this opening area can be controlled by the drive circuit shown in FIG. 3b. The aperture area of the 4D diaphragm means is read by the detection value of the angle encoder attached to the movable part of the galvanometer. This read value is compared with the set value corresponding to the desired opening area, and the drive circuit of 4E operates so that these signals have the same value, and the opening area of 4D is held.

A DA conversion signal output from 16 controllers can be used as the setting value of the opening area. For example, if 8-bit data output is used, a 256-step setting range can be obtained, and almost continuous control is possible.

In this case, the procedure for setting the aperture value can be roughly divided into two methods.

First method: In a manner similar to that of the first embodiment, the aperture is first set to the open state and the brightness of the bright portion of the screen is measured. As a result, how many times the measured value was the final desired brightness was calculated, the aperture value that was the inverse multiple of the brightness was set, and the aperture value was fixed.

Second method: This is a method in which the aperture opening is closed-loop controlled so that the desired brightness is finally set, and the aperture value is fixed when it is stable.

FIG. 5 shows the processing flow. Since it is the same as FIG. 4 up to the middle, the description thereof is omitted, and the description will be made after the brightness of the bright portion of the screen is acquired and the optimum light amount is determined.

First, a white screen having the maximum brightness is projected and the brightness is measured to determine the optimum brightness. If the brightness is not sufficient for the optimum brightness at that time, the brightness cannot be further increased. Therefore, the process is terminated and the process proceeds to the next gamma setting. On the other hand, if the brightness is too high, the diaphragm is driven in the direction of narrowing it, and the driving for narrowing down is performed until the luminance becomes optimum. When the optimal luminance is reached, the driving for narrowing down is finished and the aperture value is fixed. Next, the process shifts to the optimum gamma setting process.

By setting the aperture value by either of the above two methods, it is possible to set the brightness with considerably higher accuracy than in the first embodiment.

[0056]

According to the first aspect of the present invention, both the condition of the screen, which is the projection region, and the condition outside the projection region can be grasped, so that the optimum condition according to the distance to the screen, the reflectance, and the brightness of the surrounding environment can be obtained. Projection conditions can be set automatically.

According to the second aspect, since the gradation on the screen which is the projection area can be accurately measured, the gamma setting can be optimized.

According to the third aspect, since the maximum projection light amount can be set, it becomes possible to optimally perform gradation expression including brightness.

For example, if the movie source is under the same darkness condition as in a theater of a commercial movie theater, the screen brightness is set to the same value and the gamma is set to the same gamma value. This makes it possible to provide video with the same settings as in a movie theater.

If the same dark condition cannot be obtained, the brightness of the screen is increased and the gamma value is decreased to obtain the best correction even under the condition not so suitable for watching a movie. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a supplementary explanatory diagram regarding the first embodiment of the present invention.

FIG. 3 is an explanatory diagram regarding a second embodiment of the present invention.

FIG. 4 is a flowchart showing a process in the first embodiment of the present invention.

FIG. 5 is a flowchart showing a process in the second embodiment of the present invention.

FIG. 6 is a block diagram of a conventional example.

[Explanation of symbols]

11 Video input circuit 13 Gamma setting circuit 14 Display element drive circuit 15 Light source drive circuit 16 controller

Claims (3)

[Claims] 1. A front-projection type image display device includes: a first light amount measuring means for measuring a light amount (luminance) obtained from a projected space; a light amount (luminance obtained from a periphery of the projected space; ) Measuring means for measuring the light intensity, image input means for inputting an image signal, image modulating means constituted by a two-dimensional display element, light source means for obtaining light necessary for image projection, necessary for image projection Illumination optical system and projection optical system-Video signal processing means capable of changing the intensity distribution in the video modulation means with respect to the video signal input to the video input means From the first light quantity measuring means and the second light quantity measuring means A projection-type image display device having an image display means for changing the intensity distribution of the projected image output based on the measurement result. 2. The method for changing the intensity distribution of the projected image output is to change the maximum projected light amount and the density distribution between the maximum projected light amount and the minimum projected light amount. Projection display device. 3. As a measurement result from the second light quantity measuring means, a first measurement result at a first projection light quantity and a first measurement result at a first projection light quantity.
The projection-type image display device according to claim 1, wherein a total of two or more measurement results of the second measurement results in the second projection light amount smaller than the projection light amount (including non-projection light amount) are used.