JP2003149730A - Projection display device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a projection display device capable of exhibiting excellent effects in terms of image expression and adaptability to a use environment. SOLUTION: The projection type display device 1 of the present invention comprises a light source 2
And a rod lens 4 for equalizing the illuminance distribution of the light emitted from the light source 2, a liquid crystal light valve 7 for modulating the light emitted from the rod lens 4, and projecting the light modulated by the liquid crystal light valve 7. And a projection lens 8. A light control liquid crystal element 5 capable of changing the transmittance depending on the location is provided on the emission side of the rod lens 4.
, The light amount can be adjusted depending on the location on the screen.

Description

Detailed Description of the Invention

[0001]

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

[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]

A projection type liquid crystal display device uses a liquid crystal light valve as a light modulating means. The projection type display device includes a liquid crystal light valve and a digital mirror device (Digital Mirror Device). , Hereinafter, D
An optical modulation means (abbreviated as MD) has been put into practical use. However, this type of conventional projection display device has the following problems.

Sufficient contrast cannot be obtained due to light leakage and stray light that occur 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, hereafter CR)
It is inferior in terms of image quality and power when compared with an existing television receiver using T). Further, even if an attempt is made to improve the quality of the image by various kinds of image signal processing, the dynamic range is fixed, so that the sufficient effect cannot be exhibited.

As a solution to the problem of such a projection type display device, that is, a method of improving the quality and power of an image, a light modulating means (light valve) is used according to an image signal.
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. Further, in addition to the above-mentioned problems, the brightness of the light source is fixed in the current projection type display device, and therefore it is necessary to cope with the case where the brightness varies depending on the place in the room where the image is viewed. I can't.

The present invention has been made in order to solve the above problems, and can change the amount of light incident on the light modulating means without changing the light output intensity of the lamp. It is an object of the present invention to provide a projection type display device capable of exerting an excellent effect in terms of adaptability to a use environment.

[0008]

In order to achieve the above object, a projection type display device of the present invention comprises an illumination means and a uniform illumination means for making the illuminance distribution of the light emitted from the illumination means uniform. A projection type display device comprising: a light modulating means for modulating light emitted from the uniform illuminating means; and a projecting means for projecting the light modulated by the light modulating means, wherein the uniform illuminating means is rod-shaped. A position in a plane substantially perpendicular to the optical axis, which is provided with a light guide and is located on the exit side of the rod-shaped light guide so as to be substantially conjugate with the light modulating means and the illumination light. It is possible to adjust the light quantity of the light emitted from the uniform illuminating means depending on the location by controlling the light control means on the basis of information from the outside. And

The above "information from the outside" means, for example, information based on a video signal supplied to the light modulating means,
Examples include information based on the brightness situation under the use environment and information based on the user's preference.

In general, the projection type display device is provided with a uniform illuminating means for making the illuminance distribution of the light emitted from the illuminating means uniform in order to prevent the occurrence of uneven illuminance in the illuminated area. Many. As the uniform illumination means, there is known one using a rod-shaped light guide (also referred to as a rod lens, sometimes referred to as a rod lens hereinafter) or one combining two fly-eye lenses. The present invention is directed to the one using a rod-shaped light guide as the uniform illumination means. A feature of the uniform illuminating means using the rod-shaped light guide is that the emission surface of the rod-shaped light guide and the illuminated region have an optically conjugate relationship. That is, when light has a certain illuminance distribution on the emission surface of the rod-shaped light guide, the illuminance distribution is maintained even in the illuminated area.

The present inventor has paid attention to the above points and has a desired illuminance on the exit side of the rod-shaped light guide so that, for example, a bright part of an image has bright illumination light and a dark part of the image has dark illumination light. We have found that if the distribution is intentionally created, the illuminance distribution is reflected in the illuminated area as well, so that the power and expressiveness of the projected image can be improved. That is, the projection display device of the present invention, near the exit surface of the rod-shaped light guide,
By providing the light control means whose transmittance can be adjusted depending on the location and controlling the light control means based on the information from the outside, the light amount of the light emitted from the uniform illumination means in the illuminated area can be controlled. If the information from the outside is information based on the video signal, for example, the bright part of the image is bright and the dark part of the image is dark. The expressiveness can be improved. Further, not only the power and expressiveness of the image can be improved, but also the brightness of the image can be changed depending on the place according to the situation of the brightness in the use environment and the preference of the user.

The light modulating means may be composed of a liquid crystal light valve. According to this configuration, it is possible to realize a projection type liquid crystal display device which is excellent in image expressiveness and which is highly adaptable to the use environment and the preference of the user with respect to the brightness of each place of the image.

The light control means may be composed of a liquid crystal element. According to this configuration, it is possible to easily realize a light control element that can change the transmittance stepwise depending on the location by controlling the gradation of a liquid crystal element provided with a plurality of electrodes.

As the type of the liquid crystal element, a scattering type liquid crystal element whose light scattering state can be controlled can be used. When a scattering-type liquid crystal element whose light scattering state is controllable, the light from the rod-shaped light guide is scattered so as not to be transmitted to the optical system in the subsequent stage, so that the transmittance in the illuminated area can be arbitrarily adjusted. Can be controlled. Further, since the polarizing plate is not necessary for controlling the transmittance, it is possible to increase the light utilization efficiency. Furthermore, the incident light is almost 100% in the non-scattering state.
Since the light is transmitted, the brightness of the image does not become dark by installing the light control means in the optical system when the light control is not performed.

Further, as a type of the liquid crystal element, in addition to the scattering type liquid crystal element, a twisted nematic (Twisted Nema) having polarization means on the incident side and the emission side, respectively.
tic (hereinafter abbreviated as TN) type liquid crystal element can also be used. Considering the advantage of using the above scattering type liquid crystal element, when the TN type liquid crystal element is used, it seems that the utilization efficiency of light is low because the polarizing means is used, but the actual projection type liquid crystal display Since the device originally has an optical system configured to utilize polarized light, it does not have particularly low light utilization efficiency, and has good compatibility with the light control means composed of a TN type liquid crystal element, and many parts are used. It has the advantage that it does not need to be added.

In this case, in particular, a polarization converting means is provided on the incident side of the rod-shaped light guide, and this polarization converting means also serves as the incident side polarizing means of the TN type liquid crystal element and the incident side of the liquid crystal light valve. It is desirable that the polarizing plate also serves as the emission side polarization means of the TN type liquid crystal element. With this configuration, the polarizing means for the liquid crystal element forming the dimming means is not required, and the dimming means only needs the liquid crystal panel, so that the structure of the projection type liquid crystal display device can be simplified.

As for the resolution of the light control means and the light modulation means, the resolution of the light control means may be lower than the resolution of the light modulation means. The reason for this is that the dimming means is used to roughly determine the brightness distribution, and the light modulating means forms an image to be actually displayed, so that the dimming means is less This is because it does not require high resolution. Therefore, when the light control means is composed of a liquid crystal element, it is not necessary to use an active matrix type or the like in terms of cost and the like, and a passive matrix type or a segment type may be used.

When the information from the outside is a video signal supplied to the light modulation means, the area of the light control means corresponding to the dark area of the video obtained by the video signal has a low transmittance and a light area. It is desirable that the dimmer is controlled so that the corresponding region has high transmittance. With this configuration, it is possible to further increase the contrast between the bright area and the dark area of the image on the display screen, and it is possible to obtain an image with excellent expressiveness.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, an example of a projection type liquid crystal display device in which a liquid crystal light valve is used as a light modulation means and a liquid crystal element is also used as a light control means will be described as the projection type display device of the present invention. FIG. 1 is a schematic configuration diagram of the projection display device according to the present embodiment as seen from above, and FIG. 2 is a configuration diagram of the periphery of a liquid crystal element for light control of the projection display device. In each of the following drawings, in order to make each member recognizable, the scales such as dimensions are different for each member.

The projection type display device 1 of the present embodiment is shown in FIG.
As shown in FIG. 2, the light source 2 (illuminating means) and the condenser lens 3
From the rod lens 4 (uniform illumination means), the light control liquid crystal element 5 (light control means), the relay lens 6, the liquid crystal light valve 7 (light modulation means), and the projection lens 8 (projection means). It is roughly configured. The light source 2 is composed of a lamp 10 such as a high pressure mercury lamp and a reflector 11 that reflects the light of the lamp 10. The light emitted from the light source 2 is condensed by a condenser lens 3 to be emitted from the rod lens 4. It is incident on the incident end face 4a.

In the case of this embodiment, the rod lens 4 has a conjugate relationship with the liquid crystal light valve 7 on both the incident end face and the outgoing end face, and when the incident end face 4a of the rod lens 4 is viewed from the light source 2 side, the screen 12 is vertically and horizontally oriented. When the ratio is 3: 4, the shape shown in FIG. 3A is obtained, and when the ratio is 9:16, the shape shown in FIG.
It has the shape shown in. In either case, one half is the entrance end face 4a on which light is actually incident, and the other half is provided with the reflection mirror 14.

As shown in FIG. 2, the rod lens 4 has a PBS (Polarized) inside the region where the light L is incident.
A beam splitter film 15 is provided, and the above-described reflection mirror 14 having the reflection surface 14a on the inner side of the rod lens 4 is provided on the side of the incident end surface 4a. Further, the half-wave film 16 is provided at a position where the reflected light from the reflection mirror 14 reaches. The PBS film 15, the reflection mirror 14, and the half-wavelength film 16 constitute a polarization conversion unit that aligns the incident light from the light source 2 into the polarized light in the vibration direction of one direction. That is, the rod lens 4 in the present embodiment is provided with the polarization converting means on the incident side thereof.

Therefore, when an indefinite polarized light beam L in which P-polarized light and S-polarized light are mixed is incident on the rod lens 4, first, P
Polarization separation is performed by the BS film 15, for example, P polarized light is transmitted through the PBS film 15 and S polarized light is reflected by the PBS film 15. The S-polarized light reflected by the PBS film 15 is further reflected by the reflection mirror 14 and is incident on the ½ wavelength film 16. Then, the polarized light is 90 in the half-wave film 16.
The S-polarized light is converted into the P-polarized light by rotating the same degree. In this way, the indefinitely polarized light flux L incident on the rod lens 4 is emitted from the rod lens 4 in a state in which all the P-polarized light is aligned.
In the case of the present embodiment, only one half of the cross-sectional area of the rod lens 4 can be used for the incident end face 4a, but as shown in FIGS. 3A and 3B, the light flux L having a substantially circular cross section.
If 1 is focused by the condenser lens 3 at approximately the center of the incident end face 4a, no light loss occurs.

A liquid crystal element 5 for dimming is installed at the subsequent stage of the rod lens 4. Liquid crystal element 5 for light control of the present embodiment
Is a segment type liquid crystal element in which a TN type liquid crystal is sandwiched between two glass substrates having a transparent electrode formed on the inner surface.
As shown in FIG. 4, the electrode configuration of each substrate is such that the segment electrodes 18 arranged in a matrix (4 × 4 in the present embodiment) are provided on one substrate, and common on the other substrate over the entire surface. An electrode 19 is provided. The dimming liquid crystal element 5 operates in a normally white mode as a liquid crystal display element. That is, the white (bright) state is applied when no voltage is applied, and the black (dark) state is applied when a voltage is applied, and gray scale display is performed between the areas, whereby the transmittance of the dimming liquid crystal element 5 is divided into 16 regions. It is controlled arbitrarily for each.

As a concrete example of the constitution of the liquid crystal element 5 for light control, a nematic liquid crystal having Δn of 0.1 to 0.16 and positive dielectric anisotropy can be used as the TN type liquid crystal. . The cell gap is 2 to 7 μm, and the chiral pitch is adjusted by adding a chiral agent so that the twist angle becomes about 90 ° depending on the cell gap.
Further, the upper and lower substrates are each subjected to an alignment treatment in a direction intersecting with each other at 90 °. The liquid crystal element is arranged so that the polarization direction of incident light coincides with the liquid crystal alignment direction on the incident side substrate. The polarization direction of light transmitted through the liquid crystal element is 90
In order to make the polarization direction on the light valve surface the same as the conventional one, it is desirable that the polarization surface after polarization conversion is rotated by 90 degrees with respect to the case without the liquid crystal element. .

Compared with the resolution of the liquid crystal light valve 7 (for example, several hundreds × several hundreds), the resolution of the dimming liquid crystal element 5 is 4 × 4.
Although it is much lower than the above, since the dimming liquid crystal element 5 is for creating a rough brightness distribution, this level does not matter. Therefore, the segment type liquid crystal element can be adopted, and the structure and driving of the dimming liquid crystal element 5 are simplified. Alternatively, when the resolution of the dimming liquid crystal element 5 is increased a little, a passive matrix type liquid crystal element may be used if it is difficult for the segment type liquid crystal element to deal with the resolution.

For example, as shown in FIG. 2, the rod lens 4
The P-polarized light emitted from is converted into S-polarized light by the dimming liquid crystal element 5 due to the optical rotatory power of the TN type liquid crystal twisted by 90 ° when no voltage is applied, and enters the liquid crystal light valve 7 via the relay lens 6. At this time, if the transmission axis of the incident-side polarization plate 21 of the liquid crystal light valve 7 is arranged so as to transmit S-polarized light, this S-polarized light will pass through the incident-side polarization plate 21, and therefore the illumination of the liquid crystal light valve 7 (Note that reference numeral 22 is an outgoing-side polarization plate). In this way, in the normally white mode, it is possible to create a state in which the light from the light source 2 is desired to be utilized to the maximum, that is, a state in which no dimming is applied, in a state in which no voltage is applied. The power consumption can be reduced and the light utilization efficiency can be improved.

When a liquid crystal element is used for the light control means as described above, basically, since the transmittance is adjusted only by using the polarized light having one vibration direction, the incident side of the liquid crystal element 5 for light control is adjusted. A polarizing plate may be installed on each of the output side and the output side. However, since the projection type display device is usually originally provided with the polarization conversion means and the polarizing plate attached to the liquid crystal light valve, the polarization conversion means provided in the rod lens 4 is adjusted as in the present embodiment. If the incident-side polarization plate 21 of the liquid crystal light valve 7 also functions as the incident-side polarization plate of the light-use liquid crystal element 5 and the emission-side polarization means of the dimming-use liquid crystal element 5, the structure of the dimming-use liquid crystal element 5 is obtained. Since only the liquid crystal panel is required, the structure of the projection type liquid crystal display device can be simplified.

Although the TN type liquid crystal is used for the dimming liquid crystal element 5 here, a vertical alignment type liquid crystal may be used instead of the TN type liquid crystal. It is also desirable to use the normally white mode. In this case, since the P-polarized light emitted from the rod lens 4 is incident on the liquid crystal light valve 7 as the P-polarized light when no voltage is applied, the liquid crystal light valve 7
If the transmission axis of the incident side polarization plate 21 is arranged so as to transmit P-polarized light, the same operation as described above can be performed. In this case, for example, nematic liquid crystal having Δn of 0.1 to 0.16 and negative dielectric anisotropy can be used. The cell gap is set to 2 to 7 μm, and the vertical alignment treatment is performed by forming an organic vertical alignment film or an inorganic oblique deposition film on at least one of the upper and lower substrates. Since the polarization direction of the transmitted light does not change, it is not necessary to change the optical system.

Alternatively, a scattering type liquid crystal element can be used as the dimming liquid crystal element 5. In this case, the substrates that have been subjected to the alignment treatment in an appropriate direction are attached to each other at an interval of 2 to 15 μm, and the mixture of the liquid crystal and the polymer monomer is injected therein. The liquid crystal has a positive dielectric anisotropy, and the polymer monomer is an ultraviolet polymerization type. After the injection, the surface of the substrate is irradiated with ultraviolet rays to polymerize the polymer monomer to form a polymer network.
The normally white mode is also desirable for the operation of this liquid crystal element, and when there is no electric field, the liquid crystal molecule and the polymer are arranged in the same direction, so that light is transmitted as it is. When there is an electric field, the orientation of liquid crystal molecules is different from that of the polymer, and light is scattered due to the difference in refractive index generated there.
Since the light transmission efficiency decreases due to the scattering of light,
The amount of light can be reduced.

A method of controlling the liquid crystal element for light control will be described below with reference to FIGS. FIG. 6 is a block diagram showing the configuration of the drive circuit of the projection type display device of this 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, as a basic configuration, DSP (1), DSP that are digital signal processing blocks, as described below, are used.
Circuits such as (2) are required.

In this 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. The DSP (1) 32 determines the brightness control signal from the video signal. DSP (2) 3
3, the dimming element driver 3 based on the brightness control signal
4, and finally the dimming element driver 34 actually drives the dimming element 35 (the dimming liquid crystal element 5 in the case of the present embodiment). On the other hand, the video signal is converted into an analog signal again by the DA converter 37, input to the panel driver 38, and supplied from the panel driver 38 to the liquid crystal light valve 7.

Regarding the control method of the liquid crystal element 5 for light control,
There are a method of controlling in accordance with the displayed image and a method of controlling in accordance with the use environment and user's preference. Each method will be described below.

[1] Display image adaptive control First, display image adaptive control is applied, that is, the display image is adapted so that the light amount is increased in a bright portion and decreased in a dark portion in one screen. Consider the case of performing brightness control. First, before determining the brightness control signal for each block, the average brightness control signal over the entire image is determined. In this case, as described above, the brightness control signal is determined by the DSP (1) 32 based on the video signal, but the following two 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, it is assumed that a video signal including the number of gradations of 0 to 255 in 256 steps. When attention is paid to an arbitrary one frame that forms a continuous image, 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. 7. In the case of this figure, the number of brightest gradations included in the histogram is 190.
Therefore, the 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 distribution of the number of appearances (histogram) for each gradation number included in the frame of interest, a certain ratio (for example, 10%) of the number of appearances from the maximum brightness.
A method of using the number of gradations to be the brightness control signal. For example, when 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 than the histogram. If the number of gradations corresponding to 10% is 230, this number of gradations 230 is used as the brightness control signal. Even if there is a sudden peak in the vicinity of the number of gradations 255 as in the histogram shown in FIG. 8, if the method of (a) is adopted, the number of gradations 255 becomes the brightness control signal. 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%.

By the above procedure, after determining the brightness control signal that averages the entire image, this time, the brightness control signal is determined for each individual block, and weighting is performed between the blocks. In the case of the present embodiment, since the dimming liquid crystal element 5 can adjust the transmittance for each of the 16 divided regions, for example, as shown in FIG. 9, the screen is divided into 4 × 4 blocks. The brightness control signal is divided for each of the blocks A ₁₁ , ..., A ₄₄ by the above method (a) or (b).

For example, assume that a certain image is as shown in FIG. In this image, the lower right side of the screen is bright and the upper left side is dark. Based on this image, the brightness control signal is determined for each 4 × 4 block obtained by dividing the screen by the above method, and weighting is performed between the blocks. For example, the lower right side of the screen shown in FIG. 8 blocks are “8” in 10-level evaluation, 3 blocks on the upper left side of the screen are “2”, 5 blocks in between are “5”, and the average brightness of the entire screen is “5”. ".

At this time, when the average brightness control signal of the entire screen is determined to have the number of gradations of 128, for example, if the light amount of the maximum brightness (the number of gradations of 255) is 100%, then 128 /
The light control element 35 is driven so that a light amount of 255 = 50% is obtained. Therefore, of the 16 areas of the liquid crystal element for light control, when the areas corresponding to the 5 blocks of evaluation “5” match the average brightness, the transmittance of this area is 50%. To control. Then, the variation width with respect to the average brightness is set to ± 50% of the transmittance of 50%, and the minimum transmittance is set to 75% in the area corresponding to the eight blocks of the maximum brightness evaluation “8”. The transmittance is 2 in the area corresponding to the three blocks of the brightness evaluation “2”.
Each is controlled to be 5%. Here, the change width with respect to the average brightness is set to ± 50%, but it is desirable to set it within 50%. This is because if the width of change in brightness is made larger than this, the light adjustment liquid crystal element 5 changes too much in brightness as compared with the case where the liquid crystal light valve 7 is used, and the image looks sensuously unnatural.

As a result of such dimming, the luminance distribution on the screen is as shown in FIG. 5 (c). By performing the brightness control as described above, the display screen shown in FIG.
The contrast between the bright area and the dark area of the image as shown in (a) can be further emphasized, and an image with excellent expressiveness can be obtained.

Next, in the DSP (2) 33, the light control element driver 34 is controlled based on the brightness control signal determined by the above method. The following three methods can be considered as this method.

(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 dimming element driver 34, the DSP (2) 33
Signal processing in is 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 dimming element 34 is controlled only when the brightness control signal changes by a predetermined magnitude or more (for example, 60 gradations or more). According to this method, it is possible to perform control according to only scene switching.

[2] Control from the outside The dimming element 35 can be controlled in accordance with the use environment and the preference of the user. For example, when viewing an image in a room, if there is a distribution of brightness such as near the window or inside the room, the amount of light is high on the bright side of the surrounding environment and low on the dark side. The optical element 35 is controlled.
Alternatively, if it is desired to reduce the brightness of the subtitle portion in the video according to the user's preference, the light control element 35 is controlled so that the light amount is reduced in the lower area of the screen where the subtitle is displayed, for example. 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, in order to perform this control, circuits such as the DSP (1) 32 and the DSP (2) 33 in FIG. 6 are unnecessary, but other circuit configurations are required.

In the projection type display device 1 of the present invention, a liquid crystal element 5 for dimming capable of controlling the transmittance depending on the location is provided on the exit side of the rod lens 4, and is controlled based on information from the outside. By doing so, the rod lens 4
The amount of light emitted from the device can be adjusted depending on the location within the image display area. For example, if the information from the outside is information based on the image signal, the bright part of the image is bright and the dark part of the image is illuminated. By adjusting the light so that it is dark, the power and expressiveness of the image can be improved. Further, not only the power and expressiveness of the image can be improved, but also the brightness of the image can be changed depending on the place according to the situation of the brightness in the use environment and the preference of the user.

In the case of the present embodiment, since the dimming means is composed of the segment type liquid crystal element capable of controlling the transmittance in each of the 16 divided regions, the transmittance can be changed stepwise depending on the place. The optical element can be realized with a simple structure. In particular, when a TN type liquid crystal element is used as the dimming liquid crystal element 5, there is an advantage that compatibility with the optical system of the entire projection type liquid crystal display device is good and the number of parts used can be reduced. When a scattering-type liquid crystal element is used as the dimming liquid crystal element 5, the light utilization efficiency is high, and the brightness of the image becomes dark because the dimming element is inserted into the optical system without dimming. Never.

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 specific configurations of the rod lens, the polarization conversion unit, and the like and the specific configuration of the liquid crystal element for light control, which are exemplified in the above embodiments, can be appropriately changed. Further, the projection type display device of the present invention can be applied not only to the one using the liquid crystal light valve as the light modulating means but also to the one using the DMD as the light modulating means.

[0049]

As described above in detail, in the projection type display device of the present invention, the rod-shaped light guide body is provided with the light control means capable of changing the transmittance depending on the location, and the light control means. By controlling the light source based on information from the outside, the amount of light incident on the light modulating means can be changed depending on the area without changing the light output intensity of the lamp. If the information is based on the above, it is possible to improve the power and expressiveness of the image by adjusting so that the illumination light is bright at the bright portion of the image and the illumination light is dark at the dark portion of the image. Further, not only the power and expressiveness of the image can be improved, but also the brightness of the image can be changed depending on the place according to the situation of the brightness in the use environment and the preference of the user.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a projection type display device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of the periphery of a light control liquid crystal element of the projection type display device.

FIG. 3 is a front view showing an incident end face of a rod lens used in the projection type display device.

FIG. 4 is a schematic diagram showing an electrode configuration of the light control liquid crystal element.

FIG. 5 is a diagram for explaining the control method of the liquid crystal element for dimming, showing an example of an image of (a) and (b).
The light control pattern of the liquid crystal element for light control and (c) the brightness distribution on the screen are respectively shown.

FIG. 6 is a block diagram showing a configuration of a drive circuit of the light control liquid crystal element.

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

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

FIG. 9 is a diagram illustrating a method of determining a brightness control signal for each block.

[Explanation of symbols]

1 Projection display device 2 Light source (illumination means) 4 Rod lens (uniform illumination means) 5 Liquid crystal element for light control (light control means) 7 Liquid crystal light valve (light modulator) 8 Projection lens (projection means)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H088 EA13 EA33 GA02 HA18 HA20                       HA21 HA24 HA28 HA30 JA05                 2H089 HA21 QA16 RA05 TA15 TA16                       TA17 TA18 TA20 UA05                 2H091 FA10Z FA17Z FA23Z FA41Z                       FD21 HA07 LA17 MA07

Claims (8)

[Claims] 1. Illuminating means, uniform illuminating means for equalizing the illuminance distribution of light emitted from the illuminating means, light modulating means for modulating the light emitted from the uniform illuminating means, and the light modulating means. And a projection means for projecting light modulated by the light source, wherein the uniform illuminating means has a rod-shaped light guide, and the light is emitted at the exit side of the rod-shaped light guide. The modulation means and a dimming means capable of changing the transmittance depending on a position in a plane substantially perpendicular to the optical axis at a position where they are substantially conjugate with each other with respect to the illumination light are provided. A projection type display device characterized in that the light quantity of the light emitted from the uniform illuminating means can be adjusted depending on the location by controlling the light means. 2. The projection type display device according to claim 1, wherein the light modulator is a liquid crystal light valve. 3. The projection type display device according to claim 1, wherein the light control unit includes a liquid crystal element. 4. The projection display device according to claim 3, wherein the liquid crystal element is a scattering liquid crystal element capable of controlling a light scattering state. 5. The projection display device according to claim 3, wherein the liquid crystal element is a twisted nematic liquid crystal element having polarization means on each of an incident side and an emission side. 6. The polarization conversion means is provided on the incident side of the rod-shaped light guide, the polarization conversion means also functions as the incidence side polarization means of the twisted nematic liquid crystal element, and the incidence side polarization of the liquid crystal light valve. The projection type display device according to claim 5, wherein the plate also serves as an emission side polarization unit of the twisted nematic liquid crystal element. 7. The resolution of the light control means is lower than the resolution of the light modulation means.
The projection type display device according to any one of 1. 8. The information from the outside is a video signal supplied to the light modulating means, and a region of the dimming device corresponding to a dark region of a video obtained by the video signal has a low transmittance. The projection display device according to any one of claims 1 to 7, wherein the light control unit is controlled such that a region corresponding to a bright region has a high transmittance.