JP2012175601A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device capable of preventing a double image from being viewed when displaying a stereoscopic image.SOLUTION: A projector 1 (image display device) comprises: an image display unit 2 that displays an image; and an image processing unit 24 that, when image information input to the image display unit 2 is stereoscopic image information, performs image processing for lowering the contrast of the image as compared with a case where the image information is image information other than stereoscopic image information.

Description

  The present invention relates to an image display device.

  A technique for three-dimensionally expressing a display image using a projection display device has been proposed. In this case, the display image can be viewed three-dimensionally by allowing the observer to selectively view two images shifted by the viewpoints of the right eye and the left eye, so-called parallax images, with the respective eyes.

  As one means to realize this kind of stereoscopic image display, a stereoscopic video display device that makes it possible to visually recognize a stereoscopic video by alternately displaying a right-eye image and a left-eye image in a time-sharing manner for each frame is proposed. (See Patent Document 1 below). When using this stereoscopic image display device, the observer wears shutter glasses that open and close the right and left eyes alternately. The switching of the opening and closing of each eye of the shutter glasses is synchronized with the switching of the display of the right eye image and the left eye image, and the observer can use the right eye image for the right eye and the left eye image for the left eye. To selectively view each. Thereby, the observer can visually recognize a stereoscopic image.

JP 2009-232249 A

  As described above, in the stereoscopic video display device of Patent Document 1, the opening / closing operation of each eye of the shutter glasses and the switching operation of the display of the right-eye image and the left-eye image are synchronized. That is, by opening the right eye of the shutter glasses during the display period of the right eye image and opening the left eye of the shutter glasses during the display period of the left eye image, the right eye image is displayed only by the right eye and the left eye image. Can be selectively visually recognized only by the left eye. However, in reality, there is a timing difference between the opening / closing operation of the shutter glasses and the switching operation of the display, so that the right eye image is reflected in the left eye and the left eye image is reflected in the right eye, a so-called phenomenon. Crosstalk occurs. As a result, there is a problem that an image looks double when a stereoscopic image is displayed.

  SUMMARY An advantage of some aspects of the invention is that it provides an image display device that can prevent an image from appearing double when a stereoscopic image is displayed.

  In order to achieve the above object, an image display device according to the present invention includes an image display unit that displays an image, and the image information is stereoscopic when the image information input to the image display unit is stereoscopic image information. And an image processing unit that performs image processing for reducing the contrast of the image as compared to the case of image information other than image information.

  The present inventor has found that a double image caused by crosstalk at the time of displaying a stereoscopic image becomes easier to see when the display contrast is high. According to the image display device of the present invention, when the image information input to the image display unit is stereoscopic image information, the image processing unit compares the image information with image information other than the stereoscopic image information. Therefore, even if crosstalk occurs, it is difficult to see the double image, and the display quality of the stereoscopic image can be improved.

The image display device of the present invention includes an image information determination unit that determines whether or not the image information input to the image display unit is stereoscopic image information, and the image processing unit is operated by the image information determination unit. It is desirable that the image processing be performed when it is determined that the image information is stereoscopic image information.
According to this configuration, the image information determination unit determines whether or not the input image information is stereoscopic image information, and the image processing unit performs image processing when it is determined that the image information is stereoscopic image information. Therefore, it is not necessary for the user to determine whether or not the image is a stereoscopic image, and the apparatus can be easily used.

In the image display device of the present invention, the image processing unit calculates the output light amount when the input signal is 0% in the gamma characteristic between the input signal corresponding to the image information and the output light amount of the image display unit. It is desirable to set a value larger than 0%.
According to this configuration, the output light amount when the input signal is 0% is set to a value larger than 0%, so that the overall black display luminance is increased, and so-called black is floated. Thereby, the light leakage in the black display part by crosstalk becomes inconspicuous, and it can prevent effectively that a double image is visually recognized.

In the image display device of the present invention, it is desirable that the image display unit alternately displays the right-eye image and the left-eye image in a time division manner.
There are various stereoscopic image display methods such as a time division method using shutter glasses, a polarization method using polarized glasses, and a wavelength division method using spectroscopic glasses. Generally, the time division method generates less crosstalk. It is said. Therefore, according to this configuration, the degree of reduction in contrast can be suppressed to a low level, and the display quality of a stereoscopic image can be improved overall.

It is a schematic block diagram which shows the image display part of the projector of one Embodiment of this invention. It is a figure which shows the structure of the circuit part of a projector. It is a flowchart which shows operation | movement of a circuit part. It is a figure which shows the gamma characteristic of a projector. It is a figure for demonstrating how a double image looks.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The projector according to this embodiment is a so-called three-plate type liquid crystal projector including three sets of liquid crystal light valves for red light modulation, green light modulation, and blue light modulation. From the right eye image and the left eye image, This is an example of a projector capable of displaying a stereoscopic image.

FIG. 1 is a schematic configuration diagram illustrating an image display unit of the projector according to the present embodiment. FIG. 2 is a diagram illustrating a configuration of a circuit unit of the projector according to the present embodiment. FIG. 3 is a flowchart showing the operation of the circuit unit. FIG. 4 is a diagram illustrating an example of gamma characteristics of the projector according to the present embodiment. FIG. 5 is a diagram for explaining how the double image looks.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

  As shown in FIG. 1, the image display unit 2 of the projector 1 according to the present embodiment includes a light source 3, dichroic mirrors 4 and 5, reflection mirrors 6, 7 and 8, an incident lens 9, a relay lens 10, an exit lens 11, and a liquid crystal. It comprises light valves 12R, 12G, 12B, a cross dichroic prism 13, a projection lens 14, and the like. In addition, an integrator optical system for making the illuminance distribution of light emitted from the light source 3 uniform, and a polarization conversion optical system that aligns the polarization state of the light emitted from the light source 3 with the polarization used in the liquid crystal light valves 12R, 12G, and 12B. May be provided.

  The light source 3 includes a discharge lamp 16 such as an extra-high pressure mercury lamp or a metal halide lamp, and a reflector 17 that reflects light from the discharge lamp 16. The dichroic mirror 4 has a function of transmitting the red light LR included in the white light from the light source 3 and reflecting the blue light LB and the green light LG. The dichroic mirror 5 has a function of transmitting the blue light LB and reflecting the green light LG. Therefore, the red light transmitted through the dichroic mirror 4 is reflected by the reflection mirror 6 and is incident on the red light liquid crystal light valve 12R. The green light LG reflected by the dichroic mirror 4 is reflected by the dichroic mirror 5 and enters the green light liquid crystal light valve 12G.

  Further, the blue light reflected by the dichroic mirror 4 passes through the dichroic mirror 5. For blue light, a light guide optical system 18 including a relay lens system including an incident lens 9, a relay lens 10, and an exit lens 11 is provided in order to prevent light loss due to a long optical path. Blue light is incident on the blue light liquid crystal light valve 12B via the light guide optical system 18.

  The three color lights modulated by the liquid crystal light valves 12R, 12G, and 12B are incident on the cross dichroic prism 13. The cross dichroic prism 13 is formed by bonding four right-angle prisms. A dielectric multilayer film reflecting red light and a dielectric multilayer film reflecting blue light are formed in an X shape at the interface. Yes. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 19 by the projection lens 14 which is a projection optical system, and the image is enlarged and displayed.

  In this embodiment, when stereoscopic image information is input to the image display unit 2, the right-eye image and the left-eye image are projected while being alternately switched in a time division manner. At this time, the observer can visually recognize the stereoscopic image by wearing shutter glasses in which the right eye and the left eye are alternately opened and closed in synchronization with the switching of the images. In addition, when plane image information is input to the image display unit 2, the plane image is always projected. Therefore, the observer can appropriately view either the stereoscopic image or the planar image according to the input image information.

  In addition to the image display unit 2 shown in FIG. 1, the projector 1 according to the present embodiment includes an image information determination unit 21, a DC power supply unit 22, a discharge lamp lighting unit 23, an image processing unit 24, and the like as shown in FIG. A circuit unit 25 is provided. The projection system 26 including the user side includes the projector 1 and shutter glasses 27.

Hereinafter, the configuration of the circuit unit 25 and the operation of the circuit unit 25 will be described with reference to the flowchart of FIG.
The image information determination unit 21 includes an image signal conversion unit 28 and a CPU 29 (Central Processing Unit). The image information determination unit 21 determines whether or not the image information to be projected is stereoscopic image information for switching between a right eye image and a left eye image and outputting them alternately at a predetermined switching timing. Is.

First, an image signal (luminance-color difference signal, analog signal, etc.) is input to the image signal converter 28 (step S1 in FIG. 3).
Next, the image signal converter 28 converts the image signal SG1 input from the outside into a digital RGB signal having a predetermined word length to generate image signals SG2R, SG2G, SG2B (step S2 in FIG. 3). At this time, the image signal conversion unit 28 receives the right-eye image and the left-eye image as image signals when stereoscopic image information in which the right-eye image and the left-eye image are alternately switched at a predetermined timing is input. The synchronization signal SG3 is supplied to the CPU 29 based on the switching timing with the eye image.

  Based on the synchronization signal SG3, the CPU 29 determines whether the image information to be projected is stereoscopic image information that is output by alternately switching between the right eye image and the left eye image (step of FIG. 3). S2). A determination result SG4 as to whether or not the image information is stereoscopic image information is output to the image processing unit 24.

  Further, the CPU 29 controls the operation from the start of lighting of the projector 1 to the turning off of the projector 1. Specifically, the CPU 29 outputs a lighting command and a lighting command to the discharge lamp lighting unit 23 via the communication signal SG5. Further, the CPU 29 receives lighting information of the discharge lamp 16 from the discharge lamp lighting unit 23 via the communication signal SG6. Furthermore, based on the synchronization signal SG3, the CPU 29 outputs a control signal SG7 for controlling the shutter glasses 27 in synchronization with the image signal SG1 to the shutter glasses 27 via a wired or wireless communication unit.

  When it is determined that the image information is not stereoscopic image information, for example, the image information is planar image information (reference numeral B1 in FIG. 3), the image processing unit 24 applies the three image signals SG2R, SG2G, and SG2B. Then, normal image processing including gamma correction is performed (step S5 in FIG. 3). After the image processing, the image processing unit 24 generates drive signals SG8R, SG8G, and SG8B for driving the liquid crystal light valves 12R, 12G, and 12B, and uses the drive signals SG8R, SG8G, and SG8B as the liquid crystal light valves 12R, 12G and 12B are supplied (step S6 in FIG. 3).

  On the other hand, when it is determined that the image information is stereoscopic image information (reference numeral B2 in FIG. 3), the image processing unit 24 adjusts the gamma characteristic (step S4 in FIG. 3). Specifically, in the gamma characteristic between the input image signal and the output light amount of the image display unit, the output light amount when the image signal is 0% is set to a value larger than 0%. That is, the gamma characteristic is set in a direction in which the contrast of the projected image is lowered.

  FIG. 4 shows the gamma characteristic that is the relationship between the input image signal and the output light quantity of the image display unit 2. In FIG. 4, the gamma characteristic when the image information is planar image information is indicated by a broken line, and the gamma characteristic when the image information is stereoscopic image information is indicated by a solid line. The horizontal axis of FIG. 4 indicates the input signal (%, the maximum value is 100%), and the vertical axis indicates the output light quantity (%, the maximum value is 100%). Although an example in which the gamma value is 1 is shown here, the gamma value can be appropriately set to a desired value, for example, 2.2 or the like often used.

  In the gamma characteristic in the planar image information indicated by the broken line in FIG. 4, the output light amount when the image signal is 0% is set to 0%. On the other hand, in the gamma characteristic in the stereoscopic image information indicated by the solid line in FIG. 4, the output light quantity when the image signal is 0% is set to 10%. The output light quantity when the image signal is 100% is set to 100%.

  Therefore, when the image processing unit 24 determines that the image information is stereoscopic image information, the image processing unit 24 performs image processing including gamma correction based on the gamma characteristic indicated by the solid line in FIG. 4 on the three image signals SG2R, SG2G, This is performed on SG2B (step S5 in FIG. 3). Thereafter, the image processing unit 24 generates drive signals SG8R, SG8G, and SG8B for driving the liquid crystal light valves 12R, 12G, and 12B, respectively, and these drive signals SG8R, SG8G, and SG8B are generated as the liquid crystal light valves 12R, 12G, and 12B. (Step S6 in FIG. 3).

  The DC power supply unit 22 converts an AC voltage supplied from an external AC power supply 30 into a constant DC voltage, and an image signal conversion unit on the secondary side of a transformer (not shown, but included in the DC power supply unit 22). 28, the image processing unit 24, the CPU 29, and the discharge lamp lighting unit 23 on the primary side of the transformer are supplied with a DC voltage.

  The discharge lamp lighting unit 23 generates a high voltage between the pair of electrodes of the discharge lamp 16 when the projector 1 is started up, thereby causing a dielectric breakdown to form a discharge path. Thereafter, the discharge lamp 16 maintains a discharge. Drive current I1 is supplied.

  The liquid crystal light valves 12R, 12G, and 12B modulate the luminance of the color light incident on the liquid crystal light valves 12R, 12G, and 12B via the image display unit 2 based on the drive signals SG8R, SG8G, and SG8B. To do.

  The shutter glasses 27 include a right shutter 32R and a left shutter 32L. The right shutter 32R and the left shutter 32L are controlled to open and close based on the control signal SG7. When the user wears the shutter glasses 27, the right eye 32 can be blocked by closing the right shutter 32R. When the user wears the shutter glasses 27, the left shutter 32L is closed so that the visual field on the left eye side can be blocked. The right shutter 32R and the left shutter 32L can be constituted by, for example, liquid crystal shutters.

Here, for example, a case is assumed in which a three-dimensional image that appears as if a white rectangle protrudes toward the near side on a black background is displayed.
In this case, the image for the left eye projected on the screen is as shown in FIG. 5 (A), and the image for the right eye is as shown in FIG. 5 (B). ing. However, since a timing shift is unavoidable between the switching operation between the image for the left eye and the image for the right eye and the opening / closing operation of the shutter glasses, the image for the left eye is reflected in the right eye, and the image for the right eye is Crosstalk is reflected in the left eye.

  At this time, images actually seen by the left eye are shown in FIGS. FIG. 5C shows a case where the display contrast is low, and FIG. 5D shows a case where the display contrast is high. 5 (C) and 5 (D), symbol A is a white region for both the left eye and right eye, symbol B is a black region for both the left eye and right eye, and symbol C is white for the left eye and right The eye is a black region, and the symbol D is a region where the left eye is black and the right eye is white.

  Among these, the region where the image looks double due to the crosstalk is the region of symbol D. In the area D, the white part of the right-eye image is reflected in the area where the left eye should have seen black, and is visually recognized as gray. As shown in FIG. 5D, when the display contrast is high, the gray region D is clearly visible. On the other hand, as shown in FIG. 5C, when the display contrast is low, the brightness of the surrounding black area B is increased, so that the gray area D is not so noticeable.

  In the projector 1 according to this embodiment, when the image information input to the image display unit 2 is stereoscopic image information, the gamma characteristic is set based on the gamma characteristic in which the output light amount when the image signal is 0% is set to 10%. Correction is performed. As a result, the white display side does not change so much, but the luminance on the black display side becomes high, and so-called black is in a floating state. That is, the display contrast is lowered. Accordingly, as shown in FIG. 5C, light leakage at the black display portion due to crosstalk becomes less noticeable, and it is possible to effectively prevent the double image from being visually recognized.

  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, the image information determination unit determines whether the image information is stereoscopic image information, and the image processing unit adjusts the gamma characteristic based on the determination result. Instead of this configuration, the projector has a planar image display mode and a stereoscopic image display mode, and the user can select the above two display modes with a switch or the like, and the stereoscopic image display mode is selected. In this case, the gamma characteristic may be adjusted.

  Further, as an example of a stereoscopic image display method, an example of a time division method using shutter glasses has been described, but the present invention may be applied to a polarization method using polarized glasses and a wavelength division method using spectroscopic glasses. In the above embodiment, an example of a projector is given as the image display device. However, the present invention may be applied to a direct-view image display device. In addition, the specific configuration of the image display unit and the circuit unit of the image display device is not limited to the above-described embodiment, and can be changed as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... Projector (image display apparatus), 2 ... Image display part, 21 ... Image information determination part, 24 ... Image processing part.

Claims (4)

An image display unit for displaying an image;
An image for performing image processing for reducing the contrast of the image when the image information input to the image display unit is stereoscopic image information as compared with the case where the image information is image information other than stereoscopic image information. An image display device comprising: a processing unit. An image information determination unit that determines whether the image information input to the image display unit is stereoscopic image information;
The image display device according to claim 1, wherein the image processing unit performs the image processing when the image information determination unit determines that the image information is stereoscopic image information.   The image processing unit sets the output light amount when the input signal is 0% to a value greater than 0% in the gamma characteristic between the input signal corresponding to the image information and the output light amount of the image display unit. The image display device according to claim 1, wherein the image display device is an image display device.   The image display device according to any one of claims 1 to 3, wherein the image display unit alternately displays a right-eye image and a left-eye image in a time division manner.