JP2003149741A - Lighting apparatus, and projection type display device and driving method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting apparatus used for a projection type display device which can vary the quantity of light incident on an optical modulating means without varying the light output intensity of a lamp and display superior effects on video expressing power and adaptability to use environment. SOLUTION: The lighting apparatus is equipped with a light source, a uniform lighting means, and an optical filter which constitutes a light control means of adjusting the quantity of the projection light from the light source. According to a video signal supplied from the optical modulating means, the angle of rotation of the optical filter is controlled to adjust the quantity of light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device, a projection type display device and a driving method thereof, and more particularly to a projection type device which is excellent in image expressive power and which can obtain an image of brightness suitable for a use environment and a user's preference. The present invention relates to a display device and a lighting device used for the display device.

[0002]

2. Description of the Related Art In recent years, the development of information equipment has been remarkable, and the demand for thin, high-resolution, low-power-consumption display devices has been increasing, and research and development have been advanced. 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 needs. As one form of such a liquid crystal display device, there is known a projection type liquid crystal display device (liquid crystal projector) that enlarges and projects an image emitted from an optical system using a liquid crystal light valve onto a screen through a projection lens.

[0003]

The projection type liquid crystal display device uses a liquid crystal light valve as the light modulating means. However, in the projection type display device, in addition to the liquid crystal light valve,
A device that uses a digital mirror device (hereinafter, abbreviated as DMD) as an optical modulator has been put into practical use. However, this type of conventional projection display device has the following problems.

(1) Sufficient contrast cannot be obtained due to light leakage or stray light that occurs in various optical elements constituting the optical system. Therefore, the gradation range (dynamic range) that can be displayed is narrow, and the cathode ray tube (Cathode Ray Tube,
Compared with an existing television receiver using a CRT), it is inferior in image quality and power.

(2) Even if an attempt is made to improve image quality by various kinds of image signal processing, a sufficient effect cannot be exerted because the dynamic range is fixed.

As a solution to the problem of such a projection type display device, that is, a method of expanding the dynamic range, a light modulating means (light valve) according to a video signal is used.
It is conceivable to change the amount of light incident on. The simplest way to achieve this is to change the light output intensity of the lamp. Japanese Patent Laid-Open No. 3-179886 discloses a method of controlling the output light of a metal halide lamp in a projection type liquid crystal display device.

However, a high-pressure mercury lamp is currently the mainstream as a lamp used in a projection type liquid crystal display device, but it is extremely difficult to control the light output intensity with the high-pressure mercury lamp. Therefore, there is a demand for a method capable of changing the amount of light incident on the light modulator according to the image signal without changing the light output intensity itself of the lamp.

In addition to the above-mentioned problems, since the brightness of the light source is fixed in the current projection type display device, the screen becomes too bright in a dark viewing environment, and the projection distance and projection There is also a problem that when the projection screen size is changed by zooming the lens, the brightness of the screen changes accordingly.

The present invention has been made in order to solve the above-mentioned problems, and can change the amount of light incident on the light modulating means without changing the light output intensity of the lamp, and the image expressing power and An object of the present invention is to provide a projection type display device that can exhibit an excellent effect in terms of adaptability to a use environment, and an illumination device used for the same.

[0010]

In order to achieve the above object, an illuminating device of the present invention is an illuminating device used for illuminating a light modulating means of a projection type display device. Uniform illumination means for making the illuminance distribution of the light incident from the light source uniform, and dimming means for adjusting the amount of light emitted from the light source, wherein the dimming means comprises an optical filter having a transmittance distribution. The amount of light is adjusted by the portion of the optical filter that is inserted into the optical path.

As a means for adjusting the amount of light incident on the illuminated area without changing the light output intensity of the light source, the present inventor has compared the conventional illumination device with a light amount based on information from the outside. It has been found that it is sufficient to add a dimming means for adjusting the. The above-mentioned "information from the outside" includes, for example, information based on a video signal supplied to the light modulating means,
Examples include information based on the projection magnification rate, information based on the situation of brightness under the use environment, and information based on the user's preference.

That is, according to the illuminating device of the present invention, the dimming means for adjusting the quantity of light emitted from the light source is provided,
The light control means is composed of an optical filter having a transmittance distribution, and the portion of the optical filter to be inserted into the optical path is controlled based on information from the outside supplied to the light modulation means. According to such a configuration, the optical filter is moved based on the information from the outside supplied to the optical modulator, and the optical filter is inserted into the optical path to adjust the position of the optical filter. The amount of light to be applied can be easily adjusted with good response.
Therefore, when the illumination device of the present invention is used in a projection display device, due to the function of the dimming means, for example, when the information from the outside is information based on a video signal, the amount of light is high if the video scene is bright at that time. In order to increase the amount of light, the amount of light emitted from the light source is adjusted so that the amount of light decreases in a dark scene. In this way, even when the light output intensity of the light source remains constant, it is possible to obtain light with brightness corresponding to the image in the illuminated area, which can contribute to the expansion of the dynamic range of the projection display apparatus. Similarly, it is possible to obtain the light having the brightness according to the projection magnification rate, the situation of the brightness under the use environment, the preference of the user, and the like.

Further, the optical filter is formed in a disc shape, and a transmittance distribution is provided along the circumferential direction of the optical filter, and the optical filter is rotatable with respect to a rotary shaft provided perpendicularly to the optical filter. However, it is preferable that the light amount can be adjusted by the rotation angle. With such a configuration, if a transmittance distribution is formed in the circumferential direction and then rotated, the transmittance is easily changed, so that excellent responsiveness can be obtained. Further, the number of mechanical parts of the lighting device can be reduced.

Further, in addition to the above disc shape, it is formed in a fan shape, and a transmittance distribution is provided along the circumferential direction thereof, and the rotation is about an axis of rotation provided at the apex of the central angle. It is possible, and an optical filter that adjusts the amount of light according to its rotation angle can also be suitably used. According to such a configuration, the transmittance change in the optical filter surface becomes steeper as compared with the case where the optical filter is formed into a disc shape, but since the rotation angle can be small by that amount, for example, information from the outside Based on this, when the transmittance (light quantity) is changed significantly, the light quantity transmitted through the optical filter can be adjusted with better responsiveness.

As a specific form of the uniform illuminating means, a rod integrator can be used which makes the illumination light uniform by superimposing light from a lamp using a rod lens. In this case, it is preferable to dispose the optical filter on the light incident side of the rod lens.
At this position, effective illumination light is collected in a relatively small area, so that the amount of light can be controlled efficiently and with good controllability by inserting an optical filter, which is a light control means, there. Also, after passing through the optical filter, the illumination light is superimposed by the rod lens etc.,
Light having a uniform illuminance distribution can be supplied to the light modulator, and the illuminance distribution does not occur on the screen.

A fly-eye integrator can be used as the uniform illumination means. In this case, the optical filter is preferably arranged between the light source and the first fly-eye lens. According to such a configuration, the illumination light before entering the fly-eye integrator has a light intensity distribution by the optical filter, but by passing the light through the fly-eye integrator, in the illuminated area, The illuminance distribution can be reduced, and the illuminance distribution is unlikely to occur on the screen.

Further, it is preferable that at least the surface of the optical filter on the side irradiated with light has light reflectivity. According to such a configuration, it is possible to prevent the reflected light from the optical filter from being unnecessarily scattered and to adversely affect the display. Further, since the optical filter does not absorb light, it is possible to prevent the temperature rise in that portion and prolong the life of the optical filter.

The optical filter having light reflectivity is installed so as to be inclined with respect to the optical axis, and a light absorbing material for absorbing the reflected light is provided in a direction in which the reflected light from the optical filter reaches. Is preferred. According to such a configuration, even when the components of the lighting device are arranged in the direction in which the reflected light from the optical filter reaches, it is possible to prevent the components from increasing in temperature and causing a problem. can do. Further, it is possible to prevent the reflected light from becoming stray light and adversely affecting the display.

The optical filter having light reflectivity preferably has a transmittance distribution by changing the film thickness of the metal film having light reflectivity. Such an optical filter having light reflectivity is easy to manufacture and can perform fine light control.

Among the optical filters, those having a light absorbing property on at least the surface on the side irradiated with light can also be suitably used. With such a configuration, it is not necessary to consider the reflected light from the optical filter, so that the configuration of the lighting device can be simplified.

The optical filter has a transmittance of 100.
% Area is provided, and that area preferably has an area equal to or larger than the light flux area incident on the optical filter. With such a configuration, it is possible to prevent the loss of the light amount at the time of 100% transmission.

The optical filter is preferably rotated by a stepping motor. With such a configuration, the optical filter can be rotated based on the information supplied from the outside to the light modulating means, and the amount of light passing through the optical filter can be easily adjusted with good responsiveness.

The projection type display device of the present invention comprises an illumination means,
What is claimed is: 1. A projection type display device, comprising: a light modulating means for modulating light emitted from an illuminating means; and a projecting means for projecting the light modulated by the light modulating means, wherein the illuminating device of the present invention is the illuminating means. It is characterized by having. According to such a configuration, the dynamic range of the projection display device is expanded because the illumination device is provided with which the light with the desired brightness can be obtained in the illuminated area even when the light output intensity of the light source remains constant. Therefore, it is possible to realize a projection type display device which is excellent in image expression power and adaptability to a use environment.

Further, the projection type display device of the present invention is based on a control signal determining means for determining a control signal for controlling the dimming means on the basis of a video signal per frame forming an image, and on the basis of the control signal. It is desirable to include dimming control means for controlling the dimming means, and video signal expansion means for expanding the video signal based on the control signal. According to such a configuration, the control signal for controlling the dimming means is first determined in the control signal determining means on the basis of the video signal for one frame forming an image, and the dimming control means outputs the control signal. By controlling the light control means based on the light, the light whose brightness changes according to the image is supplied to the light modulation means, while the video signal expansion means expands the video signal to an appropriate gradation range based on the control signal. . By this operation, the dynamic range of the projection type display device can be expanded, and the projection type display device excellent in image expression power and adaptability to the usage environment can be realized.

The driving method of the projection display device of the present invention is the above-mentioned driving method of the projection display device of the present invention, wherein the light control means is controlled based on a video signal per frame forming an image. By determining the control signal and controlling the dimming unit based on the control signal, the light amount of the light that illuminates the light modulating unit is adjusted, and the video signal is expanded to an appropriate gradation range based on the control signal. An image is generated by supplying the expanded video signal to the optical modulator. With such a configuration, it is possible to extend the dynamic range of the projection display device and obtain an image with high image expression power.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Projection Display Device] An embodiment of the present invention will be described below with reference to the drawings. First, a projection type liquid crystal display device, which is an example of a projection type display device including the illumination device of the present invention, will be described with reference to FIGS. The projection type liquid crystal display device of the present embodiment is
This is a three-plate projection type color liquid crystal display device provided with a transmissive liquid crystal light valve for each of different colors (red), G (green) and B (blue). FIG. 5 is a schematic configuration diagram showing this projection type liquid crystal display device, in which reference numeral 1 is an illuminating device, 2 is a light source, and 9 is a light source.
Is a rod lens (uniform illumination means), 5 is an optical filter (dimming means), 13 and 14 are dichroic mirrors, 1
Reference numerals 5, 16, 17 denote reflection mirrors, 22, 23, 24 liquid crystal light valves (light modulation means), 25 a cross dichroic prism, and 26 a projection lens (projection means).

The illuminating device 1 in the present embodiment comprises a light source 2, a condenser lens 10, a rod lens 9 and an optical filter 5. The light source 2 includes a lamp 7 such as a high-pressure mercury lamp and a reflector 8 that reflects the light from the lamp 7. Further, a rod lens 9 is installed as a uniform illuminating means for making the illuminance distribution of the light source light uniform in the liquid crystal light valves 22, 23, 24 which are the illuminated areas. In the case of the present embodiment, the optical filter 5 is rotatably arranged on the light incident side of the rod lens 9 as a light control unit for adjusting the amount of light emitted from the light source 2. The configuration of the lighting device 1 will be described in detail later.

The configuration of the latter stage of the illumination device 1 will be described below together with the action of each component. The blue light / green light reflecting dichroic mirror 13 transmits the red light L _R of the light flux from the light source 2 and also transmits the blue light L _B and the green light L _G.
To reflect and. Dichroic mirror 13
The red light L _{R that} has passed through is reflected by the reflection mirror 17 and is incident on the red light liquid crystal light valve 22. On the other hand, of the color light reflected by the dichroic mirror 13, the green light L
_G is reflected by the dichroic mirror 14 for reflecting green light and enters the liquid crystal light valve 23 for green light. On the other hand, the blue light L _B also passes through the dichroic mirror 14, passes through a relay system 21 including a relay lens 18, a reflection mirror 15, a relay lens 19, a reflection mirror 16 and a relay lens 20 and enters a blue light liquid crystal light valve 24. It

The three color lights modulated by the liquid crystal light valves 22, 23 and 24 are incident on the cross dichroic prism 25. This prism is formed by laminating four right-angle prisms, 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 thereof. These dielectric multilayer films combine the three color lights to form light representing a color image.
The combined light is projected on the screen 27 by the projection lens 26 which is a projection optical system, and an enlarged image is displayed.

Next, a driving method of the projection type liquid crystal display device 30 of this embodiment will be described. FIG. 6 is a block diagram showing the configuration of the drive circuit of the projection type liquid crystal display device 30 of the present embodiment. In the case of a conventional projection-type liquid crystal display device that does not have a dimming function, the input video signal is directly supplied to the liquid crystal panel driver after undergoing appropriate correction processing. In the case of the present embodiment in which control is performed based on signals, the basic configuration is a DSP that is a digital signal processing block as described below.
Circuits such as (1) to DSP (3) are required.

In the present embodiment, as shown in FIG. 6, a video signal input as an analog signal passes through an AD converter 31 and is a DSP which is a first digital signal processing circuit.
(1) Input to 32 (control signal determining means). DSP
In (1) 32, the brightness control signal is determined from the video signal. The DSP (2) 33 (dimming control means) controls the dimming element driver 34 based on the brightness control signal, and finally the dimming element driver 34 controls the dimming element 35 (in the case of the present embodiment). Actually drives the optical filter 5).

On the other hand, the brightness control signal determined by the DSP (1) 32 is also input to the DSP (3) 36 (video signal expanding means) together with the video signal. The DSP (3) 36 expands the video signal into an appropriate gradation range based on the brightness control signal. The video signal after the expansion processing is converted into an analog signal again by the DA converter 37, and then input to the panel driver 38. From the panel driver 38, the red light liquid crystal light valve 22 (R panel in FIG. 6) and the green light are input. The liquid crystal light valve 23 for blue light (the same G panel) and the liquid crystal light valve 24 for blue light (the same B panel) are supplied.

Here, regarding the control method of the illumination device 1, in addition to [1] display image adaptive type control, [2] control by projection magnification ratio, [3] control from the outside, etc. can be considered.
Hereinafter, each method will be described. [1] Display video adaptive control First, consider the case of performing display video adaptive control, that is, the brightness control adapted to the display video such that the light amount increases in a bright scene and decreases in the dark scene. . In this case, as explained above, the DSP
In (1) 32, the brightness control signal is determined based on the video signal, and the following three methods are possible, for example.

(A) A method of using, as the brightness control signal, the number of gradations having the maximum brightness among the pixel data included in the frame of interest. For example, assume a video signal including the number of gradations of 0 to 255 in 256 steps. When attention is paid to any one frame forming a continuous image, it is assumed that the appearance number distribution (histogram) for each gradation number of the pixel data included in the frame is as shown in FIG. 7A. In the case of this figure, since the brightest gradation number included in the histogram is 190, this gradation number 190 is used as the brightness control signal. This method is a method capable of expressing brightness most faithfully with respect to an input video signal.

(B) From the appearance distribution (histogram) for each number of gradations included in the frame of interest, the number of gradations that gives a constant ratio (for example, 10%) to the number of appearances from the maximum brightness is determined. Brightness control signal method. For example, if the distribution of the number of appearances of the video signal is as shown in FIG. 8, the region of 10% is taken from the brighter side of the histogram. If the number of gradations corresponding to 10% is 230, this number of gradations 230 is used as the brightness control signal. If there is a sudden peak in the vicinity of the gradation number 255 as in the histogram shown in FIG. 8, the gradation number 255 becomes the brightness control signal if 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 number of gradations is 23
This method in which 0 is used as the brightness control signal can be said to be a method of making a determination based on a region having meaning as information in the entire screen. In addition, you may change the said ratio in the range of about 2-50%.

(C) The screen is divided into a plurality of blocks,
A method in which the average value of the gradation numbers of the pixels included in each block is calculated, and the maximum value is used as the brightness control signal. For example, as shown in FIG. 13, the screen is divided into m × n blocks, and the average value of the brightness (the number of gradations) for each block A ₁₁ , ..., A _mn is calculated, and the maximum value is calculated. An object is used as a brightness control signal. It is desirable that the number of screen divisions is about 6 to 200. This method is a method that can control the brightness without damaging the atmosphere of the entire screen.
Regarding the above methods (a) to (c), in addition to the determination of the brightness control signal for the entire display area, the above method may be applied only to a specific portion such as the central portion of the display area. I can. In this case, it is possible to perform a control method in which the brightness is determined from the part the viewer is paying attention to.

Next, in the DSP (2) 33, the dimmer element driver 34 is controlled based on the brightness control signal determined by the above method. For this method, for example, the following three ways are possible.

(A) A method of controlling in real time according to the output brightness control signal. In this case, DSP
(1) Since the brightness control signal output from 32 may be directly supplied to the light control element driver 34, the DSP
(2) The signal processing in 33 becomes unnecessary. This method is ideal in that it perfectly follows the brightness of the image, but the brightness of the screen may change in a short cycle depending on the content of the image, causing problems such as extra stress when viewing. There is a fear.

(B) LPF is applied to the output brightness control signal.
(Low-pass filter) is applied and the output is controlled. For example, the LPF cuts the change of the brightness control signal for 1 to 30 seconds or less, and controls by the output. According to this method, since minute changes in time are cut off, it is possible to avoid changes in brightness and darkness in a short cycle as described above.

(C) A method of detecting a switching edge of the brightness control signal. The dimmer element driver 34 is controlled only when the brightness control signal changes by a predetermined magnitude or more (for example, 60 gray scales or more). According to this method, it is possible to perform control according to scene switching and the like.

In this way, for example, when the gradation number 190 is determined as the brightness control signal, if the light amount of the maximum brightness (gradation number 255) is 100%, then 190/255 =
The light control element 35 is driven so that a light amount of 75% is obtained. In the case of the present embodiment, since the light control element 35 is specifically the optical filter 5, the optical filter 5 is moved so that the transmittance becomes 75%. Similarly, the number of gradations is 23
When 0 is the brightness control signal, 230/255 = 90
The dimming element 35 is driven so as to obtain a light amount of%.

On the other hand, in the DSP (3) 36, the DSP
(1) Based on the brightness control signal and the video signal determined in 32, the video signal is expanded into an appropriate gradation range. For example, when expanding to the maximum gradation range, the maximum number of gradations that can be displayed is 255 in the above example, so if the brightness control signal is 190 gradations in the example of FIG. Number 0-19
As shown in FIG. 7B, the video signals up to
Extend to 255. By controlling the amount of illumination light and expanding the image signal, it is possible to expand the dynamic range of the image and realize smooth gradation expression.

[2] Control Based on Projection Magnification Ratio Control is performed according to zooming of the projection lens 26. Normally, the amount of light per unit area in the liquid crystal light valve (illuminated area) is constant, so the screen tends to be dark on the enlargement side and bright on the reduction side. Therefore, in order to correct this, the light control element 35 is controlled so that the light amount increases when it is changed to the enlargement side and decreases when it is changed to the reduction side.

[3] External control Allows the user to control the light control device 35 according to his / her preference. For example, in a dark viewing environment, the amount of light is low,
In a bright viewing environment, the light control element 35 is controlled so that the light amount is increased. In this case, the configuration may be adjusted by the user using the controller or by directly operating the light control element, or may be automatically controlled by providing a brightness sensor or the like. However, these
When controlling [2] and [3], the DSP (1) shown in FIG. 6 is used.
A circuit such as 32 to DSP (3) 36 is unnecessary,
Other circuit configurations are required.

[Illumination Device-1] Next, an illumination device according to the first embodiment of the present invention will be described with reference to FIG. In the present embodiment, an example of the illuminating device 1 in which the optical filter 5 is arranged between the light source 2 and the rod lens 9 is shown. Figure 1
It is a side view which shows the schematic structure of the illuminating device 1 of this Embodiment.

As shown in FIG. 1, the illumination device 1 of the present embodiment comprises a light source 2, a condenser lens 10 for condensing the light emitted from the light source 2, a rod lens 9, and an optical filter 5. ing. The light source 2 includes a lamp 7 such as a high pressure mercury lamp and a reflector 8 that reflects the light from the lamp. The rod lens 9 is a liquid crystal light valve that is an illuminated area in which the illuminance distribution of the light emitted from the light source 2 is obtained by passing light that has entered the rod lens from various directions while refracting in various directions. 22, 23, 24
Function as a uniform illuminating means for uniformization.

An optical filter 5 having a transmittance distribution serves as a light control means for adjusting the amount of light emitted from the light source 2.
Is rotatably installed between the light source 2 and the rod lens 9. Driving means (not shown) such as a stepping motor is connected to the rotary shaft, and the dimming element driver 3
The optical filter 5 can be rotated with a high-speed response by receiving a drive signal from the optical filter 4.

As shown in FIG. 2A, the optical filter 5 is preferably disk-shaped having a rotation axis. In this case, the optical filter 5 has a transmittance distribution depending on its rotation angle. For example, a disc-shaped optical filter 5
Of the above, the transmittance from the predetermined position to 90 degrees is 10
The region of 0% is formed so that the transmittance becomes lower as it becomes larger than 90 degrees. The minimum transmittance of the optical filter of FIG. 2 is set to 20%. At this time, as for the transmittance distribution of the optical filter 5, for example, the regions other than 100% transmittance are divided into eight equal parts, and the transmittances are 90%, 80%,
The transmittance may be 0%, ..., 20%, or a transmittance distribution may be formed continuously, and the transmittance may be 20% when finally rotated 360 degrees from a predetermined position. Further, it is desirable that the region having a transmittance of 100% has an area equal to or larger than the light flux region incident on the optical filter 5. With such a configuration, the number of mechanical components can be reduced, and the light amount can be adjusted with good responsiveness. In addition, it is possible to prevent the loss of the light amount at the time of 100% transmission.

Further, as shown in FIG. 2B, the optical filter 5 is formed in a fan shape and has a transmittance distribution along its circumferential direction, and is provided at the apex of the center angle. It is also possible to use a device that can rotate with respect to the rotating shaft and that adjusts the amount of light according to the rotation angle. The transmittance distribution in this case is also 90% in order by dividing the region.
%, 80%, 70%, ..., 20%,
You may form continuously. For example, as shown in FIG. 2B, when the size of the fan-shaped optical filter 5 is one fourth of the disk-shaped optical filter, the fan-shaped optical filter 5 is three times as large as the disk-shaped optical filter. Since the transmittance distribution has a size of, the change in transmittance becomes larger than that of the disk-shaped one even if it is rotated a little. Therefore, the fan-shaped optical filter 5 has a steep change in transmittance, but the rotation angle can be small correspondingly. Therefore, when the transmittance (light amount) is significantly changed based on information from the outside, the responsiveness is good. Rotate the optical filter 5,
It can be adjusted to obtain the desired amount of light. Further, when the transmittance is 100%, the portion without the optical filter 5 (the dotted line portion) can be used, so that the loss of the light amount in that case can be completely eliminated. According to such a configuration, the number of mechanical parts can be reduced, the loss of the light amount at the time of 100% transmission can be prevented, and the rotation angle is smaller than that of the disc-shaped optical filter 5, so that the response characteristics can be further improved. You can

According to the illuminating device 1 of the present embodiment, the rotatable optical filter 5 is provided between the light source 2 and the rod lens 9 constituting the uniform illuminating means, and this optical filter 5 is used for external information. Since it is configured to rotate at high speed based on, the amount of light is adjusted so that the amount of light is increased when the image scene of the projection-type image device is bright, and is decreased when it is dark. To be done. Thus, even if the output intensity of the light source 2 such as a high-pressure mercury lamp whose light output intensity is difficult to control remains constant, the liquid crystal light valves 22, 23, and 24 can obtain illumination light with brightness according to the image. Therefore, it is possible to contribute to the expansion of the dynamic range of the projection display device.

[Illumination Device-2] Next, an illumination device according to a second embodiment of the present invention will be described with reference to FIG. The illumination device 1 according to the present embodiment includes a light source 2, fly-eye lenses 3 and 4, and an optical filter 5. The difference from the first embodiment is that the fly-eye lenses 3 and 4 serve as uniform illumination means. Is to use. Therefore,
In this embodiment, referring to FIG. 3, the fly-eye lens 3,
4 will be described, and description of common parts will be omitted. Further, when the fly-eye lenses 3 and 4 are used as the uniform illuminating means, the condenser lens 10 becomes unnecessary.
The fly-eye lenses 3 and 4 have a first fly-eye lens 3 and a second fly-eye lens 4 sequentially installed from the light source 2 side. Each fly-eye lens 3 and 4 is composed of a plurality of lenses. Two fly-eye lenses 3, 4
A plurality of secondary light source images are formed by the first fly-eye lens 3, and the plurality of secondary light source images are superposed through the second fly-eye lens 4 so that the light emitted from the light source 2 is It functions as a uniform illuminating means for making the illuminance distribution uniform in the liquid crystal light valves 22, 23, 24 which are the illuminated areas.

An optical filter 5 having a transmittance distribution serves as a light control means for adjusting the amount of light emitted from the light source 2.
Are arranged, but there are two positions, that is, between the first fly-eye lens 3 and the second fly-eye lens 4 and between the light source 2 and the first fly-eye lens 3. In the present invention, the latter is preferable, and according to such a configuration, the illuminance distribution in the illuminated area can be made smaller, and light having a uniform illuminance distribution can be supplied to the light modulating means.

According to the configuration of this embodiment, a plurality of secondary light source images are formed by the first fly-eye lens 3,
The plurality of secondary light source images are superposed by the second fly-eye lens 4, so that the liquid crystal light valves 22, 2
The uniformity of the illuminance at the positions 3 and 24 can be further enhanced, and the illuminance distribution is unlikely to occur on the screen.

[Illumination Device-3] Next, an illumination device according to a third embodiment of the present invention will be described with reference to FIG. The illumination device 1 of the present embodiment includes a light source 2, a condenser lens 10,
It is composed of a uniform illumination means, a light absorbing material 6, and an optical filter 5. The optical filter 5 used in the illumination device 1 of the present embodiment has at least the surface on the side irradiated with light having light reflectivity. Further, as shown in FIG. 4, an optical filter 5 having light reflectivity is installed so as to be inclined with respect to the optical axis, and a light absorbing material that absorbs the reflected light in the direction in which the reflected light from the optical filter 5 reaches. 6 is provided.

The light source 2 is composed of a lamp 7 such as a high pressure mercury lamp and a reflector 8 as in the first embodiment. Although the rod lens 9 is used as the uniform illumination means of the illumination device 1 of the present embodiment in FIG. 4, a fly-eye lens may be used. In this case, as described in the second embodiment, the optical filter 5 is preferably arranged between the light source 2 and the first fly-eye lens. Examples of the light absorbing material 6 include a ceramic material, asbestos, which is a non-combustible material and can absorb light efficiently. By providing this light absorbing material 6 in the direction in which the reflected light from the optical filter 5 reaches, the temperature rise in the optical filter 5 is prevented, and even if the reflected light from the optical filter 5 arrives, the lighting device 1 Even if the constituent element is arranged, it is possible to prevent the constituent element from increasing in temperature and causing a problem. In addition, such reflected light does not become stray light and adversely affects the display. The optical filter 5 having light reflectivity is obtained by forming a metal film using a metal having light reflectivity such as silver or aluminum. If the metal film is thin, the transmittance is high, and conversely, if the metal film is thick, the transmittance is low. Based on this, the optical filter 5 having a transmittance distribution can be produced by gradually changing the film thickness of the metal film. Such an optical filter 5 is
Not only is the production simple, but more precise light control can be performed.

According to the structure of the present embodiment, there is no possibility that the reflected light will be scattered unnecessarily to adversely affect the display, and the temperature rise in the optical filter 5 can be prevented.
It is possible to build a highly reliable system.

[Illumination Device-4] Next, an illumination device according to a fourth embodiment of the present invention will be described. The basic configuration of this embodiment is the same as that of the first embodiment, except that a material having a light absorbing property is used for at least the surface of the optical filter 5 on the side where light is irradiated. Only that. Therefore, in the present embodiment, only the configuration of the optical filter 5 having a light absorbing property will be described, and the description of common parts will be omitted.

Examples of the light-absorbing material include materials obtained by coating glass with a black pigment material.
The optical filter 5 having a transmittance distribution can be produced by changing the thickness of these light-absorbing materials and applying them. According to the configuration of this embodiment,
Since it is not necessary to consider the reflected light, the illuminance distribution at the positions of the liquid crystal light valves 22, 23, 24 can be made uniform with a lighting device having a simple configuration.

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, the shape and arrangement of the optical filter 5 are not limited to those in the above embodiment, but can be changed as appropriate.
In the above embodiment, the example of the projection type liquid crystal display device 30 using the liquid crystal light valves 22, 23 and 24 as the light modulating means has been described, but the present invention is applied to the projection type display device using the DMD as the light modulating means. It is also possible to do so.

[0060]

As described above in detail, according to the lighting device of the present invention, light having a brightness corresponding to an image can be obtained in the illuminated area even if the light output intensity of the light source remains constant.
It is possible to contribute to the expansion of the dynamic range of the projection display device. By using this illumination device, it is possible to realize a projection type display device having an excellent effect in terms of image expression power and adaptability to the use environment.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of a lighting device according to a first embodiment of the present invention.

FIG. 2A and FIG. 2B are front views of an optical filter.

FIG. 3 is a side view showing a schematic configuration of a lighting device according to a second embodiment of the present invention.

FIG. 4 is a side view showing a schematic configuration of an illumination device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of a projection type liquid crystal display device according to a first embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a drive circuit of the projection type liquid crystal display device.

FIG. 7 is a diagram for explaining a first method of determining a brightness control signal from a video signal in the projection type liquid crystal display device.

FIG. 8 is a diagram for explaining the second method of the same.

FIG. 9 is a diagram for explaining the third method of the same.

[Explanation of symbols] 1 Lighting device 2 light sources 3 First fly-eye lens (uniform illumination means) 4 Second fly-eye lens (uniform illumination means) 5 Optical filter (light control means) 6 Light absorber 9 Rod lens (uniform illumination means) 10 Condensing lens 22, 23, 24 Liquid crystal light valve (light modulator) 26 Projection lens (projection means) 30 Projection-type liquid crystal display device (projection-type display device) 32 DSP (1) (control signal determining means) 33 DSP (2) (control signal means) 35 Light control element 36 DSP (3) (video signal expansion means)

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Claims (14)

[Claims] 1. An illuminating device used to illuminate a light modulating means of a projection display device, comprising: a light source; a uniform illuminating means for uniformizing an illuminance distribution of light incident from the light source; and a light source. And a dimming means for adjusting the light quantity of the emitted light, the dimming means is composed of an optical filter having a transmittance distribution, and the light quantity is adjusted by a portion of the optical filter to be inserted into the optical path. Characteristic lighting device. 2. The optical filter is formed in a disk shape, and a transmittance distribution is provided along a circumferential direction thereof, and is rotatable with respect to a rotation axis provided perpendicularly to the optical filter. The illumination device according to claim 1, wherein the amount of light is adjusted by the rotation angle thereof. 3. The optical filter is fan-shaped,
A transmittance distribution is provided along the circumferential direction, and it is rotatable about a rotation axis provided at the apex of the central angle, and the amount of light is adjusted by the rotation angle. The lighting device according to claim 1. 4. The uniform illumination means is a rod integrator, and the optical filter is arranged on the light incident side of the rod integrator.
The lighting device according to any one of 1. 5. The illumination according to claim 1, wherein the uniform illumination means is a fly-eye integrator, and the optical filter is arranged between the light source and the fly-eye integrator. apparatus. 6. The illuminating device according to claim 1, wherein at least a surface of the optical filter on the side irradiated with light has light reflectivity. 7. An optical filter having light reflectivity is installed tilted with respect to the optical axis, and a light absorbing material for absorbing the reflected light is provided in a direction in which the reflected light from the optical filter reaches. The lighting device according to claim 6, wherein 8. The lighting device according to claim 6, wherein the optical filter has a transmittance distribution by changing a film thickness of a metal film having light reflectivity. 9. The lighting device according to claim 1, wherein at least a surface of the optical filter on a side irradiated with light has a light absorbing property. 10. The optical filter has a transmittance of 100%.
The illumination device according to any one of claims 1 to 9, wherein the region is provided, and the region has an area equal to or larger than a light flux region incident on the optical filter. 11. The optical filter is rotated by a stepping motor.
The lighting device according to any one of 0. 12. A projection type display device comprising: illuminating means, light modulating means for modulating the light emitted from the illuminating means, and projection means for projecting the light modulated by the light modulating means, A projection type display device comprising the illumination device according to claim 1 as the illumination means. 13. A control signal deciding means for deciding a control signal for controlling the dimming means on the basis of a video signal for one frame forming an image, and controlling the dimming means on the basis of information from the outside. 13. The projection type display device according to claim 12, further comprising: a dimming control unit that controls the video signal and a video signal expansion unit that expands the video signal based on the control signal. 14. The method for driving a projection type display device according to claim 12, wherein a control signal for controlling the light control means is determined based on a video signal per frame forming an image, By controlling the dimming means based on the information from, the light amount of the light illuminating the light modulating means is adjusted, the video signal is expanded based on the control signal, and the expanded video signal is A method for driving a projection display device, characterized in that an image is generated by supplying the image to the light modulating means.