JP5334677B2 - Projection-type image display device - Google Patents

Description

  The present invention relates to a projection-type image display device, and more particularly to a projection-type image display device that achieves high brightness by extracting a white component of an input image and adding the white component in addition to the three primary colors of red, green, and blue.

  In a conventional projection type image display device, there is a DLP projector as a typical example of the one in which the white component of the input video is extracted and the white component is added to increase the brightness. Illumination light emitted from the lamp light source is applied to the display device through a color wheel provided with segments such as red, green, blue and white.

  Some color wheels use complementary colors, such as those composed of six colors of red, green, blue, yellow, cyan, and magenta. In this case, if the same amount of yellow, cyan, and magenta are displayed, they are combined to become a white component.

  FIG. 4 is a diagram showing a configuration of a conventional DLP projector. In FIG. 4, a lamp light source 11 that emits light from an arc, a spheroid lamp reflector 12, and red, green, blue, and white filters are provided on the circumference, and the color of the transmitted light is time-divided. Based on the color wheel 13 having the function of changing the light, the light pipe 14 which is a square pipe whose inner surface is a light reflecting surface, the condensing optical system 15, and the video signal input to the image display device. A display device 16 that modulates or switches light and a lens 17 that is called a projection lens and projects image light formed on the display device 16 onto a screen are shown.

  The lamp light source 11 is generally disposed at one focal point of a lamp reflector 12 having a spheroid shape, and light emitted from the lamp light source 11 is reflected by the inner surface of the lamp reflector 12 and condensed toward the other focal point of the lamp reflector 12. To do. The lamp light source 11 is generally a high-pressure mercury lamp or halogen lamp using discharge.

  In order to capture as much light as possible, the light pipe 14 is generally arranged so that the focal position of the lamp reflector 12 on the light collecting side coincides with the incident surface of the light pipe 14. The light taken in from the incident surface of the light pipe 14 travels while being repeatedly reflected on the inner surface, and exits from the exit surface of the other end surface. The light rays are repeatedly reflected many times, so that light rays of various angles are mixed, and a light beam having a uniform cross-sectional illuminance is formed on the exit surface of the light pipe 14.

  A color wheel 13 is disposed between the lamp light source 11 and the light pipe 14, and a red, green, blue, and white filter is rotated by a motor provided to change the color of light transmitted therethrough in a time-sharing manner. That is, red, green, blue, and white light are sequentially sent to the optical system after the color wheel 13 along the time axis.

  The light beam emitted from the light pipe 14 and having a uniform illuminance distribution is condensed by the condensing optical system 15 and collected on the display device 16.

  The display device 16 generates image light by modulating or switching light based on the image signal input to the projection type image display apparatus. As an example of the display device 16, in the case of a DLP projector, a DMD (Digital Micro Mirror Device) is used, but a transmissive or reflective liquid crystal panel or the like can be used.

  Since the conventional example uses a DMD, the light reflected by the display device 16 and imaged is transmitted through the projection lens 7 and projected onto the screen to form an enlarged image.

  The display device 16 is sequentially illuminated by the action of the color wheel 13, but a video signal corresponding to the color is input to the display device 16 in synchronization with the color of the color wheel 13. As a result, red, green, blue, and white image lights are projected in sequence on the screen, but if the color change cycle is sufficiently fast, these colors are synthesized in the observer's head. It looks as a full color image as a whole.

  The color wheel 13 is a band filter of light, and the white segment transmits the most light with respect to other colors. Therefore, the larger the white segment, the higher the brightness of the projector. On the other hand, if the quantitative ratio of white addition is too large, the white component becomes too strong in the color: white luminance ratio, and the image may be uncomfortable.

  Normally, a projector has a function of adjusting a quantitative ratio of white addition, and a user can switch depending on whether priority is given to luminance or image quality.

  According to Patent Document 1, the display method of full color video and black and white video can be selected by moving the color wheel. When performing black-and-white display, the color wheel is moved to increase the brightness by irradiating the display device with light from the light source without passing through the color wheel.

JP 2003-241305 A

  In the conventional projection type image display device as described above, in the high luminance mode, the white component becomes too strong in the color: white luminance ratio, and the image may be uncomfortable. Further, in the high image quality mode, colors are displayed naturally, but there is a problem that luminance is lowered.

  In addition, switching the quantitative ratio of white addition requires user operations such as menu operation and remote control switching, and there are problems that the operation is cumbersome, such as frequent switching depending on the content. .

  The present invention has been made to solve the above-described problems. By automatically switching the quantitative ratio of the white component addition, a projection-type image display that eliminates the uncomfortable feeling of the image and the troublesome work. The purpose is to provide a device.

A projection-type image display apparatus according to the present invention includes a color wheel, a display device driving unit that displays an image by driving the color wheel according to an input video signal while performing white component addition, and the input video signal. A coloring degree detection unit that detects a coloring degree that is a degree of variation of each color component in the input video signal; and a quantitative amount of the white component addition in the display device driving unit according to the coloring degree in the coloring degree detection unit A white component addition amount control unit that changes in a stepwise manner with a time constant toward a desired quantitative ratio of the white component addition when controlling the ratio, and the white component addition amount control unit includes: As the degree of coloring increases, the quantitative ratio of the white component addition is reduced.

According to the projection type image display apparatus of the present invention, the color wheel, the display device driving unit that displays the image by driving the color wheel according to the input image signal while performing the white component addition, and the input image From the signal, a coloring level detection unit that detects a coloring level that is a variation degree of each color component in the input video signal, and the white component addition in the display device driving unit according to the coloring level in the coloring level detection unit when controlling the quantitative ratio, and a white component addition amount control unit for stepwise changed to have a time constant towards the quantitative proportion of the desired of the white component summing, the white component addition amount control unit by the larger the degree of coloration remove quantitative ratio of the white component summing, the quantitative proportion of the white component summing automatically changed without user's work, by switching, the video physical disorder The hassle of and work can be eliminated.

1 is a block diagram of a signal processing circuit according to a first embodiment of the present invention. It is a relationship diagram of the input signal level-illuminance of Embodiment 1 of this invention. It is a figure which shows the structural example of the coloring degree detection part. It is a figure which shows the basic composition of the prior art.

<A. Embodiment 1>
<A-1. Configuration>
Hereinafter, the present invention will be specifically described with reference to the drawings showing the first embodiment.

  FIG. 1 is a diagram showing a functional block configuration of a projection type image display apparatus according to Embodiment 1 of the present invention. The projection type image display apparatus includes an ADC circuit 1 that performs analog-digital conversion of an input video signal, a SCALER circuit 2 that converts the input video signal digitally converted by the ADC circuit 1 into the same pixel size as a display device, and a SCALER circuit 2. The DMD driving unit 3 included in the display device driving unit for displaying the video corresponding to the input video signal on the DMD which is the display device while adding the white component to the input video signal having the pixel size converted in FIG. Included in DMD 4 that is a display device that displays an input video signal by driving drive unit 3 and a display device drive unit that drives a color wheel in synchronization with the input video signal displayed on DMD 4 input to DMD drive unit 3 Color wheel drive circuit 5 and red / green / blue / white segments. The color wheel 6 driven in accordance with the color driving circuit 5, the coloring degree detecting unit 7 for detecting the coloring degree indicating the degree of variation of each color component of the input video signal digitally converted in the ADC circuit 1, and the coloring degree detecting unit 7 A white component addition amount control unit 8 that controls the quantitative ratio of the addition of white components according to the degree of coloring is provided.

  As described in the conventional example, some color wheels 6 use complementary colors. For example, there are those composed of six colors of red, green, blue, yellow, cyan, and magenta. Absent.

<A-2. Operation>
<A-2-1. Change in quantitative ratio of white component addition>
Next, the operation will be described. The input video signal is converted into a digital signal by the ADC circuit 1, and pixel conversion is performed by the SCALER circuit 2 to the same resolution as that of the DMD 4. The DMD driving unit 3 displays the red, green, blue, and white video signals of the RGB video signal on the DMD 4 in a time-sharing manner according to the color wheel segment based on, for example, the RGB video signal input from the SCALER circuit 2.

  At this time, the display image of the DMD 4 and the color of each segment of the color wheel 6 are synchronized by the color wheel driving unit 5. As a result, the projected video signal is synthesized in the observer's head and appears as a full-color video as a whole.

  FIG. 2 shows the relationship between the input signal level and the screen illuminance of the projected image. When the white component is not added (white addition 0%), the illuminance changes linearly between 0% and 100% of the input signal level. Actually, the input video signal has been subjected to inverse gamma correction of the power of 2.2. Here, the input signal level-illuminance will be described as changing linearly.

  When white components are added (0% <white addition ≦ 100%), if the input video signal level exceeds a certain level (for example, the level at which the branch in FIG. 2 starts), the DMD driving unit 3 in FIG. Thus, the white component addition process starts, and the maximum illuminance is reached with an amplitude of 100%. Normally, the DMD 4 performs PWM control of the micromirror to turn on / off the light and perform gradation expression. When expressing dark tones, thinning is performed by changing the two-dimensional ON / OFF location to express subtle brightness. However, since the white segment is too light and noise is conspicuous, As in the example, the quantitative ratio of the white component addition is often changed from the intermediate gradation.

  The DMD driving unit 3 generally has a function of switching the quantitative ratio of the white component addition step by step, and the slope of the illuminance UP when adding the white component can be selected as in the example of FIG. When the input signal level is maximum with a white component addition of 100%, the maximum luminance is expressed. In addition, the inclination of the white component addition of 0% indicates that white is displayed only in the red, green, and blue segments, and the color reproduction is in the most natural state with no sense of incongruity.

  Recently, there has been an improvement in the algorithm of the DMD driving unit 3 to add a white component from a lower luminance. In the first embodiment, whichever function has a function of switching the quantitative ratio of the white component addition step by step. The configuration of

<A-2-2. Change of quantitative ratio of white component addition according to coloring degree>
First, detection of the coloring degree will be described. The input video signal output from the ADC circuit 1 in FIG. 1 is input to the coloring degree detection unit 7 to detect the coloring degree, which is a so-called variation amount of each color component for one screen. The white component addition amount control unit 8 controls the DMD driving unit 3 based on the coloring degree detected by the coloring degree detection unit 7 and switches the quantitative ratio of the white component addition.

  FIG. 3 is a configuration example of the coloring degree detection unit 7. Here, for example, if the RGB signal amplitudes are the same, it is considered that there is no coloring (monochrome component), and the others are determined to be colored.

  The minimum value detection circuit 9 detects the minimum value of the input RGB signals. Thereafter, the minimum value of the RGB signals detected from the RGB signals is subtracted. As a result, one color is always 0, and in the case of a black and white signal, the values of the RGB signals are equal, so all three colors are also 0. The integration circuit 10 integrates the result for one screen and sets it as the coloring degree of the screen.

  In the first embodiment, the method of subtracting the minimum value from the RGB signals for the detection of the coloring level is shown. However, the difference between the maximum value and the minimum value of the RGB signals is defined as the coloring level as the degree of variation. Thus, it can be used for controlling the DMD driving unit 3.

  Next, the white component addition amount control unit 8 controls the DMD driving unit 3 using the color degree detected by the color degree detection unit 7 so as to decrease the quantitative ratio of the white component addition as the color degree increases. When the coloring degree is small, the DMD driving unit 3 is controlled so as to switch to the quantitative ratio of the white component addition having a large inclination shown in FIG. For example, when the coloring degree is 0, the white component addition is controlled to 100%.

  At this time, changing the setting of the white component addition quantitative ratio with an extremely large width will cause a noticeable change in the brightness of the image.Therefore, when controlling the white component addition quantitative ratio, a time constant should be provided. It is desirable to change the quantitative ratio of the white component addition step by step toward the target value.

<A-3. Effect>
According to Embodiment 1 of the present invention, in a projection-type image display device, a display device that displays a video by driving the color wheel 6 according to an input video signal while performing white component addition with the color wheel 6. A DMD driving unit 3 as a driving unit, a color wheel driving unit 5, a coloring degree detecting unit 7 that detects a coloring degree from an input video signal, and a DMD driving unit 3 according to the coloring degree in the coloring degree detecting unit 7 By including the white component addition amount control unit 8 that controls the white component addition quantitative ratio, the white component addition quantitative ratio is automatically changed and switched without the user's work. The troublesome work can be eliminated.

  Further, according to the first embodiment of the present invention, in the projection type image display apparatus, the coloring degree is the degree of variation of each color component in the input video signal, so that the white component addition is performed according to the variation of the color component. The quantitative ratio can be controlled automatically, eliminating the feeling of discomfort in the video and eliminating the hassle of work.

  Further, according to the first embodiment of the present invention, in the projection type image display apparatus, the white component addition amount control unit 8 reduces the quantitative ratio of the white component addition as the degree of coloring increases, so that the color: white The uncomfortable feeling of the image due to the extreme difference in the ratio can be reduced.

  In addition, when almost the entire screen is displayed in black and white, such as spreadsheet software, the slope of white component addition is automatically switched to increase, so that display with high luminance is possible.

  Further, according to the first embodiment of the present invention, in the projection type image display apparatus, when the white component addition amount control unit 8 controls the quantitative ratio of the white component addition, the desired white component addition quantitative amount is controlled. By changing stepwise toward the ratio, it is possible to prevent the luminance change of the video from being noticed even when the quantitative ratio of the white component addition is extremely changed.

  DESCRIPTION OF SYMBOLS 1 ADC circuit, 2 SCALER circuit, 3 DMD drive part, 4 DMD, 5 color wheel drive part, 6,13 color wheel, 7 coloring degree detection part, 8 white component addition amount control part, 9 minimum value detection circuit, 10 integration Circuit, 11 Lamp light source, 12 Lamp reflector, 14 Light pipe, 15 Condensing optical system, 16 Display device, 17 Projection lens.

Claims (1)

Color wheel,
A display device driving unit that displays a video by driving the color wheel according to an input video signal while performing white component addition;
A color level detection unit that detects a color level, which is a degree of variation of each color component in the input video signal, from the input video signal ;
When controlling the quantitative ratio of the white component addition in the display device driving unit according to the coloring degree in the coloring degree detection unit , a time constant is given toward a desired quantitative ratio of the white component addition. And a white component addition amount control unit that changes step by step ,
The white component addition amount control unit reduces the quantitative ratio of the white component addition as the coloring degree increases .
Projection-type image display device.

Images