JP2009031798A - Image display method, device, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent flicker of a display image. <P>SOLUTION: In an image display method in which luminance of the display image is adjusted by dimming processing of illuminating light, dimming processing is so carried out that the variance of display image luminance per unit time is ≤5%. The luminance of the display image is the average luminance of the whole display image. The dimming processing is carried out based on an image signal including the luminance information of the display image. The dimming processing is carried out based on the luminance of an emission light from the display image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image display method and apparatus, and a projector.

In recent years, the development of information equipment has been remarkable, and the demand for a high-resolution, low power consumption and thin image display device has increased, and research and development have been promoted. Among them, the liquid crystal display device is expected as a display device that can electrically control the alignment of liquid crystal molecules to change the optical characteristics and can meet the above-mentioned needs. As one form of such a liquid crystal display device, a liquid crystal projector that enlarges and projects a display image emitted from an optical system using a liquid crystal light valve onto a screen through a projection lens is known.
A liquid crystal projector uses a liquid crystal light valve as an optical modulator, but a projector using a digital mirror device as an optical modulator in addition to the liquid crystal light valve has been put into practical use. However, this type of conventional projector has the following problems.

(1) A sufficient contrast cannot be obtained due to light leakage and stray light generated by various optical elements constituting the optical system. For this reason, the displayable gradation range (dynamic range) is narrow, and the quality and power of the displayed image are inferior to those of an existing television receiver using a cathode ray tube (CRT).
(2) Even if an attempt is made to improve the quality of the display image by various video signal processing, the dynamic range is fixed, so that a sufficient effect cannot be exhibited.
As a solution to such a problem of the projector, that is, a method of extending the dynamic range, it is conceivable to change the amount of light incident on the light modulator (light valve) according to the video signal. The simplest way to achieve this is to change the light output intensity of the lamp. A method for controlling output light of a metal halide lamp in a projector has been proposed (see, for example, Patent Document 1).
JP-A-5-66501

High-pressure mercury lamps are currently mainstream as lamps used in projectors, but it is extremely difficult to control light output intensity with high-pressure mercury lamps. For this reason, there is a need for a method that can change the amount of light incident on the light modulation means in accordance with the video signal without changing the light output intensity itself of the lamp.
In addition to the above-mentioned problems, the brightness of the light source is fixed in the current projector. When the screen size is changed, there is a problem that the brightness of the display image changes accordingly.

  In order to solve such problems, in recent years, projector lighting apparatuses having a structure in which a light control louver (light-shielding plate) is combined with a light source such as the above-described metal halide lamp or high-pressure mercury lamp have been proposed. . Specifically, a light-shielding plate is disposed on the optical axis of light emitted from the light source, and a part of the light source light is shielded by rotating the light-shielding plate around a rotation axis parallel to the main surface. The present applicant has already filed a number of inventions relating to this type of lighting device.

  According to this configuration, the light amount of the light emitted from the light source can be arbitrarily adjusted by the dimming means provided separately from the light source. For this reason, by adjusting the illumination light based on, for example, a video signal, it is possible to obtain light with brightness according to the display image in the illuminated area (light modulation device) even when the light output intensity of the light source remains constant. This can contribute to the expansion of the dynamic range of the projector.

  On the principle that the black level changes due to the dimming and expansion processing, performing the dimming and expansion processing in synchronization with the video signal will cause an inadvertent brightness change in the video, which is inconvenient for the viewer. Recognized as flicker on the display image. On the other hand, flickering feeling given to the viewer can be suppressed by performing dimming and expansion processing at a relatively low speed without matching the switching of the video signal. However, when the processing speed is low, there is a possibility that the dimming effect cannot be sufficiently exhibited because the scene is switched before reaching the optimum dimming state. Therefore, there is a demand for an image display method that can sufficiently perform the light control process while preventing the flicker of the display image.

  SUMMARY An advantage of some aspects of the invention is that it prevents flickering of a display image while extending the dynamic range of the display image by dimming and expansion processing.

  In order to achieve the above object, an image display method according to the present invention is an image display method for adjusting the brightness of a display image by dimming illumination light, and the display image brightness per unit time is adjusted. The dimming process is performed so that the change is within 5%.

  The display image device according to the present invention is an image display device including a light source that emits illumination light, a light control element that performs light control processing on the illumination light, and a control unit that controls the light control element. The control means controls the dimming element so that a change in display image luminance per unit time is within 5%.

According to the image processing method and apparatus according to the present invention having such characteristics, the dimming processing is performed so that the change in display image luminance is within 5%.
"Stiles, WS: Color vision: the approach through increment threshold sensitivity. Proc. Natl. Acad. Sci. 45, 100-114 (1959)" (Reference 1)
According to the human visual characteristics, log N = log M + k, N / M = const (about 0.01), where M is the background light intensity and N is the threshold value of the stimulating light that can detect the difference from the background. Holds. Therefore, a human can recognize a luminance change of 1/100 of the background. That is, when there is a change in luminance of 1% of the background, it is recognized as flicker by humans.
Also, “Kelly, DH: Visual responses to time-dependent stimuli. I. Amplitude sensitivity measurements. J. Opt. Soc. Am. 51, 422-429 (1961)” (reference 2).
Shows the human temporal contrast sensitivity as a function. This reference document 2 shows whether or not a person can recognize the luminance difference when light having a predetermined luminance difference is changed at a predetermined frequency. According to this document, when light is switched at a low frequency (about 1 to 5 Hz), a human can recognize a luminance difference of about 5% at the maximum.
Therefore, as in the image processing method and apparatus according to the present invention, it is possible to prevent flickering of the display image by performing the dimming process so that the change in display image luminance is within 5%.
Note that Reference Document 2 discloses data indicating that a human can recognize a luminance difference of about 1% at maximum when light is switched at a frequency of 10 to 20 Hz. For this reason, in the image processing method and apparatus according to the present invention, it is more preferable to perform the light control processing so that the change in display image luminance is within 5%.
In addition, by determining the change in the display image luminance in this way, the speed of the dimming process can be increased to the limit within that range. For this reason, it is possible to bring out the effect of the light control processing to the maximum without causing the display image to flicker.

  Further, since the display image brightness varies depending on each area of the display screen, it is preferable to use the average brightness of the entire display image as the display screen brightness. Thereby, it is possible to prevent the display screen from flickering as a whole.

In addition, the light control processing may be performed based on a video signal including luminance information of the display image, or may be performed based on the luminance of light emitted from the display image. When performing dimming processing based on the light emitted from the display image, it is possible to perform dimming in consideration of the external light in the space where the display image is displayed, so it is more accurate based on the visual characteristics of the viewer The dimming process can be performed.
In the case where the dimming process is performed based on the emitted light from the display image, the image display device according to the present invention includes an emitted light detection unit that detects the display image luminance based on the emitted light from the display image. The dimming process is performed by controlling the dimming element based on the output signal of the emitted light detection means.

Next, a projector according to the present invention includes the image display device according to the present invention.
According to the image display device of the present invention, flickering of the display image can be prevented by performing the dimming process so that the change in display image luminance is within 5%. Therefore, the projector according to the present invention can display a high-contrast display image.

  Hereinafter, an embodiment of an image display method and apparatus and a projector according to the present invention will be described with reference to the drawings.

First, a projector according to an embodiment of the invention will be described with reference to FIGS.
The projector according to the present embodiment is a three-plate projection type color liquid crystal display device having a transmissive liquid crystal light valve for each of different colors of R (red), G (green), and B (blue). FIG. 1 is a schematic configuration diagram showing the projector. In the figure, reference numeral 1 is an illumination device, 10 is a light source, 21 and 22 are fly-eye lenses (uniform illumination means), and 32 is a light shield (light control means 30). , 41 and 42 are dichroic mirrors, 43, 44 and 45 are reflection mirrors, 51, 52 and 53 are liquid crystal light valves (light modulation means), 60 is a cross dichroic prism, and 70 is a projection lens (projection means). .

  The illuminating device 1 in this embodiment includes a light source 10, fly-eye lenses 21 and 22, and a plurality of light shielding bodies 32. The light source 10 includes a lamp 11 such as a high-pressure mercury lamp and a reflector 12 that reflects light from the lamp 11. In addition, as uniform illumination means for uniformizing the illuminance distribution of the light source light in the liquid crystal light valves 51, 52, and 53 which are illuminated areas, the first fly-eye lens 21 and the second fly-eye lens from the light source 10 side. 22 are sequentially installed. Here, the first fly-eye lens 21 divides light (illumination light) emitted from the light source 10 into a plurality of light beams R, and the second fly-eye lens 22 is a superposition lens that superimposes them at the light valve position. It has the function of. In some cases, a condenser lens for superimposing the secondary light source image may be arranged at the position of the second fly-eye lens 22 or at the subsequent stage. Hereinafter, the case where the second fly-eye lens is used as the superimposing lens will be described.

  In the case of the present embodiment, a plurality of light blocking bodies 32 rotate between the first fly-eye lens 21 and the second fly-eye lens 22 as a dimming element that adjusts the amount of light emitted from the light source 10. It is installed as possible. The configuration of the lighting device 1 will be described in detail later.

The configuration of the latter stage of the lighting device 1 will be described below together with the operation of each component.
The dichroic mirror 41 of the blue light, green light reflection, transmits red light L _R of the light beam from the light source 10, is intended to reflect the blue light L _B and the green light L _G. The red light _{LR that} has passed through the dichroic mirror 41 is reflected by the reflection mirror 45 and enters the liquid crystal light valve 51 for red light. Meanwhile, among the color light reflected by the dichroic mirror 41, the green light L _G is reflected by the dichroic mirror 42 for reflecting green light, is incident on the green light liquid crystal light valve 52. On the other hand, the blue light L _B is also transmitted through the dichroic mirror 42, a relay lens 46, reflecting mirror 43, is incident on the relay lens 47, reflecting mirror 44, liquid crystal light valve 53 for blue light through a relay system 49 comprising a relay lens 48 The

  The three color lights modulated by the liquid crystal light valves 51, 52 and 53 are incident on the cross dichroic prism 60. In this prism, four right-angle prisms are bonded, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 71 by the projection lens 70 which is a projection optical system, and an enlarged display image is displayed.

Next, a method for driving the projector according to the present embodiment will be described.
FIG. 2 is a block diagram illustrating the configuration of the drive circuit of the projector according to the present embodiment. In the case of a conventional projector that does not have a dimming function, the input video signal undergoes appropriate correction processing and is supplied to the liquid crystal panel driver as it is, but it has a dimming function and is based on the video signal. In the case of this embodiment to be controlled, circuits (control means) such as DSP (1) to DSP (3) which are digital signal processing blocks are required as a basic configuration as described below.

  In the present embodiment, as shown in FIG. 2, a video signal input as an analog signal is input to a DSP (1) 82 that is a first digital signal processing circuit via an AD converter 81. In the DSP (1) 82, the luminance control signal is determined from the video signal. The DSP (2) 83 controls the dimming element driver 84 based on the luminance control signal, and finally the dimming element driver 84 actually uses the dimming element 30 (the light shielding body 32 in this embodiment). To drive.

  On the other hand, the luminance control signal determined by the DSP (1) 82 is also input to the DSP (3) 86 together with the video signal. The DSP (3) 86 expands the video signal to an appropriate gradation range based on the luminance control signal. The video signal after the expansion process is converted again to an analog signal by the DA converter 87 and then input to the panel driver 88. The liquid crystal light valve 51 for red light (R panel in FIG. 2) from the panel driver 88 and for green light. A liquid crystal light valve 52 (G panel) and a blue light liquid crystal light valve 53 (B panel) are supplied.

  Here, the control method of the illuminating device 1 is demonstrated.

Display image adaptive control
Consider a case where display-video appropriate control, that is, luminance control adapted to a display image in which the light amount increases in a bright video scene and the light amount decreases in a dark scene. In this case, as described above, the luminance control signal is determined based on the video signal by the DSP (1) 82. For example, the following three methods are conceivable.

(A) A method in which the number of gradations having the maximum luminance among the pixel data included in the frame of interest is used as the luminance control signal.
For example, a video signal including the number of gradations of 256 steps from 0 to 255 is assumed. When attention is paid to an arbitrary frame constituting a continuous video, it is assumed that the appearance number distribution (histogram) for each gradation number of pixel data included in the frame is as shown in FIG. In this case, since the brightest number of gradations included in the histogram is 190, the number of gradations 190 is used as the luminance control signal. This method is a method that can express the brightness most faithfully to the input video signal.

(B) From the appearance number distribution (histogram) for each number of gradations included in the frame of interest, brightness control is performed on the number of gradations that is a fixed ratio (for example, 10%) with respect to the number of appearances from the maximum brightness. How to make a signal.
For example, when the appearance number distribution of the video signal is as shown in FIG. 4, an area of 10% is taken from the brighter side than the histogram. If the number of gradations corresponding to 10% is 230, this number of gradations 230 is used as the luminance control signal. When there is a sudden peak in the vicinity of the number of gradations 255 as in the histogram shown in FIG. 7, the number of gradations 255 becomes the luminance control signal when the method (a) is adopted. However, this sudden peak portion does not make much sense as information on the entire screen. On the other hand, the present method using the number of gradations 230 as the luminance control signal can be said to be a method of determining by a region having meaning as information in the entire screen. In addition, you may change said ratio in about 2 to 50% of range.

(C) A method in which a screen is divided into a plurality of blocks, an average value of the number of gradations of pixels included in each block is obtained, and the maximum one is used as a luminance control signal.
For example, as shown in FIG. 5, the screen is divided into m × n blocks, and the average value of the luminance (number of gradations) for each block A ₁₁ ,..., A _mn is calculated. Is a luminance control signal. The number of screen divisions is preferably about 6 to 200. In this method, the brightness can be controlled without deteriorating the atmosphere of the entire screen.
As for the methods (a) to (c), in addition to determining the luminance control signal for the entire display region, the method can be applied only to a specific portion such as a central portion of the display region. . In this case, it is possible to perform a control method in which the brightness is determined from the portion that is viewed by the viewer.

  Next, the DSP (2) 83 controls the dimming element driver 84 based on the luminance control signal determined by the above method. For example, the following two methods are conceivable.

(A) A method of controlling using a luminance control signal and an LUT (Look Up Table).
The relationship between the dimming step and the luminance control signal (input gradation) is prepared as an LUT so as to correspond to the output intensity obtained by the gamma curve as shown in FIG. The DSP (2) 83 derives a dimming step for a specified luminance change by comparing the luminance control signal output from the DSP (1) 82 with the LUT, and the dimming element driver 84 at a predetermined timing. Output to. For example, in FIG. 6, the luminance change rate per input gradation is within 1%.
According to human visual characteristics, when the luminance change rate is within 1%, it is almost impossible to recognize the luminance change, so the light control element is equivalent to one gradation per unit time (for example, 1/30 second). By driving 30, light control without flickering can be realized.
Note that, here, in order to surely realize dimming without flickering, the luminance change rate per input gradation is set within 1%. However, as for human visual characteristics, for example, in the case of a movie or the like in which the display image changes rapidly, the recognizable luminance change rate is about 5%. For this reason, for example, in a projector displaying a movie or the like, the light control element 30 may be controlled using an LUT such that the luminance change rate per input gradation is within 5%. Further, for any display image, flickering of the display image is suppressed by controlling the dimming element 30 using an LUT in which the luminance change rate per input gradation is within 5%. It becomes possible.
In addition, it is known that humans perceive light for a certain period of time by integrating it over time. According to the Block's law, which is the law relating to the temporal addition function of light in the human visual system, humans perceive light that is integrated over about 30 ms for bright light and about 100 ms for dark light. Therefore, the time characteristic of the visual system can be effectively utilized by setting the unit time of the luminance change to 1/30 seconds to 1/10 seconds.

  In this way, for example, when the number of gradations 190 is determined as the luminance control signal, the amount of light with the maximum luminance (the number of gradations 255) is assumed to be 100%, so that a light amount of 190/255 = 75% can be obtained. The optical element 30 is driven. In the case of the present embodiment, since the light control element 30 is specifically the light shielding plates 31 and 32, the light shielding plates 31 and 32 are rotated so that the transmittance is 75% (the light shielding rate is 25%). Similarly, when the number of gradations 230 is a luminance control signal, the light control element 30 is driven so that a light quantity of 230/255 = 90% can be obtained.

(B) A method of controlling using a dedicated control signal and LUT.
For example, the DSP (2) 86 receives a dimming speed control signal from the DSP (1) 82 separately from the luminance control signal. This is preferably a value close to the average luminance of the screen, such as the APL (average gradation level) of the video or the mode value of the histogram. The DSP (2) 86 determines a designated ratio (for example, 1%) of the dimming speed control signal as the dimming speed. This is converted into a dimming step by a LUT prepared in advance, and is output to the dimming element driver 84 at a predetermined timing. In this case, a dimming speed control signal is extracted from the video signal every unit time, and the dimming element 30 is driven so that the luminance changes by a specified ratio.

On the other hand, the DSP (3) 86 expands the video signal to an appropriate gradation range based on the luminance control signal and the video signal determined by the DSP (1) 82. For example, when expanding to the maximum gradation range, in the above example, the maximum number of gradations that can be displayed is 255. Therefore, in the example of FIG. Video signals from 0 to 190 are expanded to the number of gradations from 0 to 255 as shown in FIG. By controlling the amount of illumination light and expanding the video signal, smooth gradation expression can be realized while extending the dynamic range of the video.
When the DSP (2) 83 receives the dimming speed control signal (dedicated control signal), in addition to the luminance control signal from the DSP (1) 82, the dimming speed control signal is also sent to the DSP (3) 86. Sent. Then, in the DSP (3) 86, the luminance change per unit time is a specified ratio (for example, 1%) of the dimming speed control signal until the video signal expansion process reaches the target luminance control signal. ) Repeat the expansion process.

Next, the illumination device 1 will be described with reference to FIGS.
In the present embodiment, an example of an illuminating device in which a light shielding plate is inserted between two fly-eye lenses constituting a uniform illuminating means is shown. FIG. 7 is a diagram showing a schematic configuration of the light blocking body, and (a), (b), and (c) are a top view, a CC ′ arrow view, and a DD ′ arrow view, respectively. . FIG. 8 is a side view showing a schematic configuration of the illumination device, and a front view showing a state in which the light shielding body is viewed from the optical axis direction together with the second fly-eye lens, and (a), (b), (c). ) Indicate the states of the light attenuation rates of 0%, 30%, and 60%, respectively.

  As shown in FIG. 8, in the illuminating device 1 of this embodiment, as a uniform illumination means for equalizing the illuminance distribution of the light emitted from the light source in the liquid crystal light valve that is the illuminated area, the first illumination from the light source side. The fly eye lens 21 and the second fly eye lens 22 are sequentially installed. Each fly-eye lens 21, 22 is composed of a plurality of (for example, 6 × 6 in this embodiment) microlenses 23, 24 arranged in the X direction and the Z direction.

  Between the first fly-eye lens 21 and the second fly-eye lens 22, a pair of light-shielding bodies 32 having a three-dimensional shape as a dimming element that adjusts the amount of light emitted from the light source 10. Is installed.

  The light shielding body 32 has a structure in which a plate-like member having a non-uniform thickness is bent, and one of the front shapes (hereinafter referred to as a planar shape) has a U-shape as shown in FIG. The shape is greatly curved. Further, the front shape (hereinafter referred to as a side surface shape) viewed from a direction orthogonal to this is a substantially rectangular shape as shown in FIG. g is provided. These light shielding bodies 32 are arranged so that the curved portions shown in FIG. 7C face each other across the optical axis Y (that is, the bent end portions face each other). Centering on a rotation shaft 32c substantially perpendicular to Y, one is configured to be rotatable in a clockwise direction and the other in a counterclockwise direction. The light shielding bodies 32 are configured to have the same shape, turning radius, and the like, and the rotation shafts 32c of the light shielding bodies are disposed at positions that are symmetrical with respect to the optical axis Y. .

  As shown in FIG. 8A, these light shielding bodies 32 are arranged outside the optical path of the light emitted from the first fly-eye lens 21 in the initial state where light control is not performed, and the light shielding amount. Is configured to be substantially zero. On the other hand, when dimming (dimming state), as shown in FIG. 8B and FIG. 8C, each light shield 3 is in the range of 0 ° to 180 ° around the rotation shaft 32c. Are rotated equally within. In the present embodiment, since the light shielding body 32 has a three-dimensional shape, when the light shielding body 32 is rotated, the shape of the image obtained by projecting the light shielding body 32 onto a plane perpendicular to the optical axis Y is the shape of the light shielding body 32. A transition is made from a reflection of the planar shape to a reflection of the side shape of the light shield 32.

  For example, when the rotation amount of the light shielding body 32 is within a range of 0 ° to 90 °, the shape of the projected image is a shape reflecting the planar shape shown in FIG. 7C, and the light beam emitted from the light source 10 is The light is shielded from all directions in such a manner that it is sequentially shielded from the outer periphery toward the optical axis Y side. On the other hand, when the rotation amount of the light shielding body 32 exceeds 90 °, the shape of the projected image becomes a shape reflecting the side shape shown in FIG. 8B, and the light beam emitted from the light source 10 is the outer peripheral portion thereof. Is further shielded, and the amount of light shielding gradually increases. However, since the light shielding body 32 is provided with the recess g in the side surface shape, the amount of light shielding does not become zero even when the light shielding body 32 is rotated to 180 °, and the vicinity of the optical axis Y as shown in FIG. The light transmission region G reflecting the depression g remains.

  Thus, in this embodiment, since the three-dimensional member is rotated, compared with the case where the flat light-shielding plate mentioned above is rotated, the light control range can be expanded. That is, in the flat light shielding plate, only the planar shape contributes to light shielding, and the side surface shape (thickness shape) hardly contributes to light shielding. For this reason, the maximum light shielding amount is determined by the planar shape of the light shielding plate. On the other hand, in the light shielding body having a three-dimensional shape, not only the planar shape but also the side surface shape contributes to the light shielding. Therefore, depending on the side surface shape, a light shielding amount larger than the light shielding amount determined by the planar shape can be obtained. In the example of this embodiment, it is possible to set the maximum light shielding amount to 100% by making the side surface of the light shielding body 32 a rectangular shape (that is, not providing the recess g). On the contrary, by appropriately adjusting the size of the depression g, it is also possible to arbitrarily set a range in which dimming is allowed.

  Further, in the present embodiment, since light is preferentially shielded from light in a region away from the optical axis Y that is incident on the liquid crystal light valve at a large angle, as shown in FIG. The larger the amount, the higher the contrast of the image. For this reason, gradation reproducibility is improved even in a dark image, and a subtle gradation change can be expressed. In particular, in the present embodiment, since such light shielding is performed from all directions so as to surround the optical axis Y, the contrast of the image is the highest.

  Further, in the present embodiment, since the light control is performed line-symmetrically with respect to the optical axis Y, it is possible to realize uniform illumination with little illuminance deviation on the light valve that is the illuminated area. That is, when the light source light is shielded using the light control means, if the light control is performed unnecessarily, the effect of uniforming the illuminance distribution is hindered. For example, when dimming from one side with respect to the optical axis Y, the illuminance distribution may be biased such that only one side of the illuminated area is bright and the remaining one side is dark. On the other hand, when the light is symmetric with respect to the optical axis Y as described above, the light flux R formed by the first fly-eye lens 21 has a brightness deviation due to light shielding. However, the illuminance distribution obtained by superimposing them by the second fly-eye lens 22 is a line-symmetric distribution with respect to the axis passing through the center of the illuminated area, and asymmetrical light control is performed with respect to the optical axis Y. Compared to the case, the appearance of the projected image can be improved.

  In particular, when only the image corresponding to blue as shown in FIG. 1 is used for the projector in which the vertical direction or the horizontal direction of the image is reversed with the other two-color images, An image having a uniform color balance on both sides of the screen 71 can be reproduced.

  Moreover, in this embodiment, since the projection image of the light shielding body 32 has a shape including a curve, the change in the amount of illumination light during dimming can be smoothed. That is, in the configuration using the fly-eye lenses 21 and 22 as uniform illumination means, the partial light beam R emitted from the microlens 23 forms an image at the center of the corresponding microlens 24, so that the edge of the light shielding plate is rotated. When the portion passes through the center of the lens 24 in front view, the amount of transmitted light of the light beam R is greatly reduced. At this time, if the shape of the light shielding plate 31 is rectangular and the edge thereof is parallel to the horizontal arrangement direction (Z direction) of the microlenses, the central portions of the six microlenses 24 arranged in the Z direction are shielded from light. Since all of the light is simultaneously shielded by the plate, the change in the amount of light is further increased. Accordingly, even when it is desired to continuously change the amount of light, the luminance change of the screen may be discontinuous, and the viewer may feel unnatural when viewing the video.

  On the other hand, in the present embodiment, the shape of the light shielding body 32 has an uneven curved portion or an oblique side portion that obliquely intersects with the horizontal arrangement direction of the microlenses 24, so that the light shielding bodies 32 are arranged in a line. The central portions of the two microlenses 24 are not shielded from light at the same time. In other words, in the present embodiment, the central portions of the plurality of partial light beams R partially shielded by the rotation of the light shield are shielded at different timings, or are shielded at several separate timings. Therefore, the light quantity change can be averaged as a whole, and a discontinuous change in the illumination light quantity can be prevented.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, two light shields 32 are arranged at positions sandwiching the optical axis, but one such light shield may be used. Conversely, it is also possible to arrange three or four light shields at positions surrounding the optical axis. In this case, it is preferable that the shape and the arrangement of each light shielding body are axisymmetric about the optical axis Y. Thereby, the illuminance distribution of the light in the illuminated area is axisymmetric with respect to the central axis, and the appearance of the image is further improved.

Moreover, in the said embodiment, you may comprise a light-shielding body with a translucent member, and, thereby, a light control characteristic can be made still smoother. Specifically, the above structure can be realized by using a resin having semi-transmission characteristics for the light shielding body, or by using a glass with a metal thin film formed on the surface of the light shielding body and having a distribution in the film thickness. . In this way, when regions having different light transmittances are provided in the light shielding body, light shielding is performed with a random distribution for each of a plurality of secondary light source images created by the fly-eye lens. In the superimposition, these distributions are mixed to make the illuminance distribution uniform, and the illuminance uniformity in the illuminated area is increased.
Of course, the light shielding body may be a member having a uniform light transmittance (for example, a translucent member having a uniform transmittance distribution). In this case, there are advantages such as ease of manufacture.

  In the above embodiment, the light shielding body 32 is disposed between the first fly-eye lens and the second fly-eye lens. However, the light shielding body may be disposed on the exit side of the second fly-eye lens. . In this case as well, it is desirable to preferentially shield the light beam separated from the optical axis Y among the plurality of partial light beams emitted from the second fly-eye lens 22 by the light blocking body.

  Moreover, in the said embodiment, what used the mechanical light-shielding body as the light control means was illustrated. However, the technical scope of the present invention is not limited to such dimming means using a mechanical light shield, and for example, dimming that directly changes the output intensity of a light source such as a metal halide lamp or LED (light emitting diode). The present invention can also be applied to a projector using a light control means using liquid crystal as a light control element.

  Further, in the above-described embodiment, an example in which a transmissive liquid crystal device is used as the light modulation unit as the projector is illustrated. However, the technical scope of the present invention is not limited to such a transmission type. For example, the present invention is applied to a reflection type projector such as LCOS or a projector using a mirror type spatial light modulator based on the MEMS technology. The invention can also be applied.

1 is a diagram showing a schematic configuration of a projector according to an embodiment of the invention. The block diagram which shows the structure of the control apparatus of a projector. The figure for demonstrating the 1st method of determining a light control signal from a video signal in a projector. The figure for demonstrating the 2nd method same as the above. The figure for demonstrating the 3rd method same as the above. FIG. 4 is a diagram for explaining a method for controlling a dimming element driver based on a luminance control signal in the projector. The figure which shows schematic structure of the light control element with which the illuminating device which concerns on embodiment of this invention was equipped. The top view which shows schematic structure of a light control element, and the front view which looked at this light control element from the optical axis direction. The figure which shows the relationship between the light reduction amount of a projection type display apparatus, and contrast.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Illuminating device, 10 ... Light source, 21, 22 ... Fly eye lens, 23, 24 ... Micro lens, 30 ... Light control element, 32 ... Shading body, 32c ... Rotating shaft, 51, 52, 53 ... Liquid crystal light Valve (light modulation means), 70 ... projection lens (projection means), 82 ... DSP (1) (control means), 83 ... DSP (2) (control means), 86 ... DSP (3) (control means), R ... Partial luminous flux, Y ... Optical axis

Claims (7)

An image display method for adjusting brightness of a display image by dimming illumination light,
An image display method characterized by performing dimming processing so that a change in display image luminance per unit time is within 5%. The image display method according to claim 1, wherein the display image luminance is an average luminance of the entire display image. The image display method according to claim 1, wherein the dimming process is performed based on a video signal including luminance information of the display image. The image display method according to claim 1, wherein the light control processing is performed based on a luminance of emitted light from the display image. An image display device comprising: a light source that emits illumination light; a light control element that performs light control processing on the illumination light; and a control unit that controls the light control element,
The image display apparatus characterized in that the control means controls the light control element so that a change in display image luminance per unit time is within 5%. Emission light detection means for detecting the display image brightness based on the emission light from the display image,
The image display apparatus according to claim 5, wherein the control unit controls the dimming element based on an output signal of the emitted light detection unit. A projector comprising the image display device according to claim 5.

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