JP2008083533A - Position adjusting method for first light modulating element and second light modulating element for image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position adjustment method for the first light modulating element and second light modulating element of an image display apparatus, whereby a wider luminance dynamic range and an increased gradation number can be achieved while the image quality of a display image is improved by precisely positioning the first and second light modulating elements. <P>SOLUTION: The position adjustment method includes: the optical axis direction position adjustment step in which while the relative positions of the first light modulating element, relay optical system, and second light modulating element are shifted in the direction of the optical axis, a change in the pattern of a moire is observed, and the relative positions of the three optical members in the direction of the optical axis are adjusted; the parallelism adjustment step in which while the relative positions of the first and second light modulating elements are shifted, a change in the pattern of a moire is observed, and the parallelism of the first and second light modulating elements is adjusted; a relative rotation position adjustment step in which while the relative rotation positions of the first and second light modulating elements are shifted, a moire is eliminated, and thereby the relative rotation positions of the first and second light modulating elements are adjusted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for adjusting the position of a first light modulation element and a second light modulation element in an image display device including two light modulation elements, a first light modulation element and a second light modulation element.

In recent years, electronic display devices such as LCD (Liquid Crystal Display), EL (Electro-Luminescence) displays, plasma displays, CRTs (Cathode Ray Tubes), and projectors have been remarkably improved. Devices with nearly comparable performance are being realized. However, regarding the luminance dynamic range, the reproduction range is about 1 to 10 ² [nit], and the number of gradations is generally 8 bits. On the other hand, human vision has a range of luminance dynamic range that can be perceived at a time of about 10 ⁻² to 10 ⁴ [nit], and the luminance discrimination capability is 0.2 [nit]. It is said to be equivalent to 12 bits. When viewing the display image of the current display device via such visual characteristics, the narrowness of the luminance dynamic range is conspicuous, and in addition, the gradation of the shadow part and highlight part is insufficient, You will feel unsatisfactory with the reality and power of the displayed image.

In CG (Computer Graphics) used in movies, games, etc., the display data (hereinafter referred to as HDR (High Dynamic Range) display data) has a luminance dynamic range and gradation characteristics close to human vision. The movement to pursue reality is becoming mainstream. However, since the performance of the display device that displays it is insufficient, there is a problem that the expressive power inherent in the CG content cannot be fully exhibited.
Furthermore, in the next OS (Operating System), adoption of a 16-bit color space is planned, and the dynamic range and the number of gradations are dramatically increased as compared with the current 8-bit color space. Therefore, it is expected that there will be an increasing demand for realizing a high dynamic range and high gradation electronic display device that can make use of the 16-bit color space.

  Among display devices, a projection display device (projector) such as a liquid crystal projector or a DLP (Digital Light Processing (trademark)) projector can display a large screen and is effective in reproducing the reality and power of a display image. A display device. In this field, the following proposals have been made to solve the above problems.

  The basic structure for expanding the luminance dynamic range in the projector is to divide the luminous flux emitted from the light source into red, green and blue color lights, and modulate the separated color light with the first light modulation element to obtain desired illumination. A light amount distribution is formed, and each modulated color light is synthesized by a dichroic prism, then transmitted to a second light modulation element by a relay optical system, and the brightness is adjusted by the second light modulation element for illumination. Is. As the light modulation element, a transmission type modulation element having a pixel structure whose light propagation characteristics can be controlled independently and capable of controlling a two-dimensional transmittance distribution is used. For example, the following Patent Document 1 discloses a liquid crystal light valve that is used as the first and second light modulation elements.

Consider a case where a light modulation element having a dark display transmittance of 0.2% and a bright display transmittance of 60% is used. With a single light modulation element, the luminance dynamic range is 60 / 0.2 = 300. Since the display device corresponds to optically arranging two stages of light modulation elements having a luminance dynamic range of 300 in series, it is theoretically possible to realize a luminance dynamic range of 300 × 300 = 90000. The same idea holds for the number of gradations, and the number of gradations exceeding 8 bits can be obtained by optically arranging 8-bit gradation light modulation elements in series.
The first light modulation element and the second light modulation element are separately driven by a modulation signal generated from the video signal.
JP 2005-250440 A

In the two-modulation projection display device described in Patent Document 1, in order to accurately modulate the light modulated by the first light modulation element with the second light modulation element, the first light modulation element and the second light modulation element are used. It is necessary to align with the optical axis of light (illumination light or modulated light) with high accuracy. In addition, when a relay lens is installed between the first light modulation element and the second light modulation element, the first light modulation element, the second light modulation element, and the relay lens can be placed with high accuracy with respect to the optical axis. Need to align.
On the other hand, if the installation positions of the first light modulation element and the second light modulation element are shifted with respect to the optical axis, the light emitted from the first light modulation element in the second light modulation element The irradiation area is shifted, and the light cannot be modulated accurately. As a result, there is a problem that image quality is greatly deteriorated, such as moiré and color unevenness. However, no efficient method has been proposed so far for aligning the first light modulation element and the second light modulation element with high accuracy.

  The present invention has been made to solve the above-described problems, and is capable of improving the image quality of a display image by aligning the first light modulation element and the second light modulation element with high accuracy. Another object of the present invention is to provide a method for adjusting the position of the first light modulation element and the second light modulation element in the image display apparatus capable of realizing the expansion of the luminance dynamic range and the increase in the number of gradations.

  In the process of developing an image display device including the first and second light modulation elements (hereinafter also referred to as a two-modulation-type image display device), the inventor of the present application within the display surface of each light modulation element. Compared with the alignment in the rotation direction, the alignment in the rotation direction about the axis perpendicular to the optical axis (so-called adjustment of the parallelism of the first and second light modulation elements) is difficult. However, by adjusting the position while observing the change in the moire pattern caused by the positional deviation of the first and second light modulation elements, the parallelism of the first and second light modulation elements can be adjusted efficiently and with high accuracy. I found what I could do. More specifically, it has been discovered that when the relative positions of the first light modulation element, the relay optical system, and the second light modulation element in the optical axis direction are changed, the degree of distortion of the moire pattern changes. Further, when the parallelism of the first light modulation element and the second light modulation element is changed, the moire focus distribution in the screen (the positions of the focused area and the unfocused area) and the movement direction of the focus distribution are changed. I found a change. The inventor of the present application has come up with the following configuration of the present invention based on the above experience. The inventor of the present application uses a real optical system to check what kind of positional deviation occurs and how the moire pattern changes, and also confirms it by simulation. The simulation result will be described later.

  In order to achieve the above object, the position adjustment method of the first light modulation element and the second light modulation element in the image display device of the present invention includes a light source and a plurality of pixels whose light propagation characteristics can be controlled independently. And a first light modulation element that modulates the light emitted from the light source and a plurality of pixels that can independently control light propagation characteristics, and a first light modulation element that modulates the light emitted from the first light modulation element. A relay optical system which is disposed between the two light modulation elements and between the first light modulation element and the second light modulation element and forms an optical image by the first light modulation element on the second light modulation element And a method of adjusting the position of the first light modulation element and the second light modulation element in an image display apparatus comprising: the first light modulation element; the relay optical system; and the second light modulation element. Observe the change in the moire pattern while shifting the relative position in the optical axis direction. The optical axis direction position adjusting step of adjusting the relative position of the first light modulation element, the relay optical system, and the second light modulation element in the optical axis direction, and after the optical axis direction position adjusting step, The parallelism between the first light modulation element and the second light modulation element is adjusted by observing a change in the moire pattern while shifting the relative position between the first light modulation element and the second light modulation element. After the parallelism adjusting step and the parallelism adjusting step, the moire is eliminated while shifting the rotational relative positions of the first light modulating element and the second light modulating element, A rotation relative position adjustment step of adjusting a rotation relative position with respect to the second light modulation element.

  According to the position adjustment method of the present invention, first, a change in the moire pattern (more specifically, while shifting the relative positions of the first light modulation element, the relay optical system, and the second light modulation element in the optical axis direction) By observing the change in pattern distortion, the relative positions of the three optical elements in the optical axis direction are adjusted (optical axis direction position adjusting step). Next, by observing a change in the moire pattern (more specifically, a change in the moire focus distribution and the movement direction of the focus distribution) while shifting the relative position between the first light modulation element and the second light modulation element. The parallelism between the two light modulation elements is adjusted (parallelism adjustment step). Since the relatively difficult parallelism adjustment can be accurately performed by the above two steps, the rotational relative positions of the first light modulation element and the second light modulation element are then shifted so as to eliminate moire. Both rotation relative positions can be adjusted (rotation relative position adjustment process). As described above, highly accurate alignment of the first light modulation element and the second light modulation element can be realized.

  For example, as is well known in the semiconductor manufacturing process or the like, a method is also conceivable in which alignment is provided by providing alignment patterns on the first and second light modulation elements and aligning them with each other. When this method is applied to a two-modulation image display apparatus, the quality of the alignment is determined based on the images of the two alignment patterns superimposed on the subsequent stage of the second light modulation element. However, a relay optical system is interposed between the first and second light modulation elements, and in particular, an image of the alignment pattern of the first light modulation element is difficult to be recognized through the relay optical system. It is difficult to determine the positional deviation, and this method makes it difficult to perform highly accurate alignment. On the other hand, in the method of the present invention, since the first and second light modulation elements have a lattice structure derived from pixels originally arranged in a matrix, the position can be obtained without providing a special pattern. When misalignment occurs, moire occurs. The moire pattern is a change in parameters such as the first optical modulation element, the relay optical system, the relative position of the second optical modulation element in the optical axis direction, and the parallelism between the first optical modulation element and the second optical modulation element. Is relatively sensitive to Therefore, various adjustments of the optical element can be performed with high accuracy by observing the moire pattern.

Further, before the optical axis direction position adjusting step, a moire pattern increasing step for increasing the number of appearance of the moire patterns by shifting the rotational relative positions of the first light modulating element and the second light modulating element. It is desirable to provide further.
Even if there is a slight misalignment between the first and second light modulation elements, moire occurs, but the number of appearance of moire patterns (stripe) is small. If each step of the present invention is carried out in this state, it is difficult to grasp the change in the appearance pattern of moire, so that it is difficult to adjust each optical element and the accuracy is also lowered. Therefore, if the rotational relative positions of the first light modulation element and the second light modulation element are once shifted before the above-described steps of the present invention are performed, the number of appearance of moire patterns (stripes) increases from the original state. To do. Therefore, by this process, the moire pattern change after the next process becomes more prominent, and it is possible to accurately determine whether or not there is a positional deviation.

Further, after the optical axis direction position adjusting step, a relay magnification adjusting step of adjusting the magnification of the relay optical system by observing a change in the moire pattern while shifting the magnification of the relay optical system is further provided. Is desirable.
According to this configuration, not only the relative positional relationship between the first and second light modulation elements but also the magnification of the relay optical system can be adjusted with high accuracy.

In addition, after the rotation relative position adjustment step, horizontal and vertical adjustment patterns are displayed on the first light modulation element and the second light modulation element, respectively, and the first light modulation element and the second light modulation are displayed. It is desirable to further include a horizontal / vertical position adjusting step for adjusting the horizontal / vertical position with respect to the element.
According to this configuration, after the alignment of the first and second light modulation elements in the optical axis direction or the adjustment of the parallelism is completed, the horizontal and vertical positions of each light modulation element are aligned in the display surface. It can be carried out.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The image display apparatus of this embodiment is an example of a two-modulation projection type image display apparatus that uses liquid crystal light valves for the first light modulation element and the second light modulation element.
FIG. 1 is a schematic configuration diagram (plan view) of a projection type image display apparatus according to the present embodiment.

First, the configuration of the projection type image display apparatus will be described with reference to FIG.
The projection type image display apparatus 1 of the present embodiment includes a light source 10, a uniform illumination system 20, and a color modulation unit 30 (a blue light liquid crystal light valve 40B, a green light liquid crystal light valve 40G, and a red light liquid crystal light valve 40R. 3 liquid crystal light valves (first light modulation elements), and incident side polarizers (not shown) and emission side polarizers (not shown) disposed in the respective light valves. These liquid crystal light valves may be collectively referred to as a color modulation light valve 40), a relay lens 60 (relay optical system), an incident-side polarizer 70, and a liquid crystal light valve 80 as a luminance modulation unit (second optical modulator). 2 light modulation elements (hereinafter also referred to as luminance modulation light valves), an output side polarizer 90, and a projection lens 100 (projection optical system).

  The uniform illumination system 20 makes the luminance distribution of light incident from the light source 10 uniform. The color modulation unit 30 modulates the luminance of light of R, G, and B3 primary colors in the wavelength region of light incident from the uniform illumination system 20. The relay lens 60 transmits the light modulated by the color modulation unit 30 to the luminance modulation light valve 80. The luminance modulation light valve 80 modulates the luminance in the entire wavelength region of the light incident from the relay lens 60. The projection lens 100 projects light modulated by the luminance modulation light valve 80 onto the screen 200.

  The light source 10 includes a lamp 11 such as a high-pressure mercury lamp or a xenon lamp, and a reflector 12 that reflects light emitted from the lamp 11. The uniform illumination system 20 includes a first fly-eye lens 21, a second fly-eye lens 22, a polarization conversion element 23, and a condenser lens 24 each composed of a plurality of microlenses. In the uniform illumination system 20, the luminance distribution in the light beam cross section of the light emitted from the light source 10 is made uniform by the first fly eye lens 21 and the second fly eye lens 22. Further, the light that has passed through the first fly-eye lens 21 and the second fly-eye lens 22 is polarized and converted by the polarization conversion element 23 into the incident polarization direction of the liquid crystal light valves 40R, 40G, and 40B of the color modulation unit 30, and the polarization thereof. Is condensed by the condenser lens 24 and emitted toward the color modulation unit 30. The polarization conversion element 23 is composed of, for example, a PBS array and a half-wave plate, and converts a light beam in an indefinite polarization state into specific linearly polarized light.

  The color modulation unit 30 includes two dichroic mirrors 31 and 32 as light separation means, three mirrors 33, 34, and 35 (reflection mirrors), and five field lenses (lens 36, relay lens 37, and collimating lens 38B). , 38G, 38R), three liquid crystal light valves 40B, 40G, 40R, and a cross dichroic prism 50.

  The dichroic mirrors 31 and 32 separate (split) the light (white light) emitted from the light source 10 into three primary color lights of red (R), green (G), and blue (B). The R light transmitting dichroic mirror 31 is formed by reflecting a B light and a G light on a glass plate or the like and forming a dichroic film having a property of transmitting the R light, and the B light and the G light included in the white light from the light source 10. Reflects light and transmits R light. The B light transmitting dichroic mirror 32 is formed by reflecting a G light on a glass plate or the like and forming a dichroic film having a property of transmitting the B light. Of the G light and B light reflected by the R light transmitting dichroic mirror 31 The G light is reflected and transmitted to the collimating lens 38G, and the blue light is transmitted and transmitted to the lens 36.

The relay lens 37 transmits light in the vicinity of the lens 36 (light intensity distribution) to the vicinity of the collimating lens 38B, and the lens 36 has a function of making light incident on the relay lens 37 efficiently. In addition, the B light incident on the lens 36 is transmitted to the liquid crystal light valve 40B which is spatially separated with almost no loss of light, with the intensity distribution thereof being substantially preserved.
The collimating lenses 38B, 38G, and 38R substantially collimate the color lights incident on the corresponding liquid crystal light valves 40B, 40G, and 40R, and efficiently transmit the light transmitted through the liquid crystal light valves 40B, 40G, and 40R to the relay lens 60. It has the function to make it enter. Then, the RGB three primary colors separated by the dichroic mirrors 31 and 32 are transmitted to the above-described mirrors (reflecting mirrors 33, 34, and 35) and field lenses (lens 36, relay lens 37, collimating lenses 38B, 38G, and 38R). Through the liquid crystal light valves 40B, 40G, and 40R.

  The liquid crystal light valves 40B, 40G, and 40R are composed of a glass substrate on which pixel electrodes and switching elements for driving the thin film transistors and thin film diodes are formed in a matrix, and a glass substrate on which a common electrode is formed over the entire surface. This is an active matrix liquid crystal display element in which a TN (Twisted Nematic) type liquid crystal is sandwiched between them and a polarizing plate is arranged on the outer surface. The liquid crystal light valves 40B, 40G, and 40R are normally white mode in which white / bright (transmission) state is applied when no voltage is applied, and black / dark (non-transmission) state is applied when voltage is applied, or vice versa. The gradation between light and dark is analog controlled according to the applied voltage value. The liquid crystal light valve 40B optically modulates the incident B light based on the display image data, and emits modulated light including an optical image. The liquid crystal light valve 40G optically modulates the incident G light based on the display image data, and emits modulated light including an optical image. The liquid crystal light valve 40R optically modulates incident R light based on display image data, and emits modulated light including an optical image.

  The cross dichroic prism 50 has a structure in which four right-angle prisms are bonded to each other, and a dielectric multilayer film 52 (B light reflecting dichroic film) that reflects B light and a dielectric multilayer film that reflects R light are included therein. 51 (R light reflecting dichroic film) is formed in an X-shaped cross section. Then, the G light from the liquid crystal light valve 40G is transmitted, the R light from the liquid crystal light valve 40R and the B light from the liquid crystal light valve 40B are reflected, and these three colors of light are combined to form a color image. To do.

  The relay lens 60 forms an optical image (light intensity distribution) of the liquid crystal light valves 40B, 40G, and 40R synthesized by the cross dichroic prism 50 on a pixel surface (light incident surface) of the subsequent liquid crystal light valve 80. The luminous flux distribution formed by the liquid crystal light valves 40B, 40G, and 40R is accurately transmitted to the liquid crystal light valve 80. The relay lens 60 is an equal-magnification imaging lens composed of a front lens group and a rear lens group arranged substantially symmetrically with respect to the aperture stop. In addition, it is desirable to have both-side telecentric characteristics in consideration of the viewing angle characteristics of the liquid crystal. The front lens group and the rear lens group are configured to include a plurality of convex lenses and concave lenses. The shape, size, arrangement interval and number of lenses, telecentricity, magnification, and other lens characteristics depend on required characteristics. It can be appropriately changed.

  The liquid crystal light valve 80 is a transmissive liquid crystal light valve having the same configuration as the liquid crystal light valves 40B, 40G, and 40R described above. This is for further modulating the luminance of the optical images of the liquid crystal light valves 40B, 40G, and 40R. Then, the luminance-modulated image light is incident on the projection lens 100, and the light beam incident on the projection lens 100 is enlarged and displayed on the screen 200 (projection surface) via the projection lens 100.

Hereinafter, a method of adjusting the position of the color modulation light valve 40 and the luminance modulation light valve 80 in the projection type image display apparatus having the above configuration will be described.
Here, the position adjustment method will be described step by step with reference to the flowchart of FIG. At the same time, simulation results regarding the relationship between various positional deviations and moire patterns are shown in FIGS.

  Note that the meanings of “roll”, “yow”, and “pitch” representing the form of rotation appearing in the following description are as shown in FIG. That is, “roll” is a rotation within the display surface with the optical axis as the rotation axis (rotation with the z axis as the rotation axis), and “yow” and “pitch” are both the rotation axis in the direction perpendicular to the optical axis, The rotation axes are orthogonal to each other ("yow": rotation with the y axis as the rotation axis, "pitch": rotation with the x axis as the rotation axis).

First, the luminance modulation light valve 80 is rotated in the roll direction to generate moire (step S1, FIG. 2 moire pattern increasing step).
At this time, in the simulation, the moiré is intentionally generated by rotating in the roll direction from the normal position, but the moiré is generated from the beginning on the actual optical system due to the slight displacement of the light valve. It is thought that it is doing enough. However, if the positional deviation is small, the number of appearing moire patterns (stripes) is small, but the number of appearing moire patterns (stripes) can be increased by appropriately rotating the luminance modulation light valve 80 in the roll direction from that state. it can. As a result, the moire pattern change in the following process can be more easily seen, and it is possible to accurately determine whether or not there is a positional deviation.
Prior to or in parallel with the above process, the luminance modulation light valve 80 is moved back and forth along the optical axis so that the moire pattern can be seen most clearly. This is a focus adjustment so that the image of the color modulation light valve 40 is formed almost on the luminance modulation light valve 80. When the image of the color modulation light valve 40 is in a defocused state on the luminance modulation light valve 80, the pixel grid image of the color modulation light valve 40 is blurred and is generated between the pixel grid of the luminance modulation light valve 80. The moire pattern is also unclear. As a result, accurate position adjustment becomes difficult. On the other hand, when in focus, the moire pattern is clear and clear, and position adjustment is easy.
It should be understood that the clear / unclear moiré pattern referred to here is an expression that is almost synonymous with the visibility of the moiré pattern.
FIG. 4 shows a moire pattern M when the luminance modulation light valve 80 is rotated by 0.5 ° in the roll direction.

Hereinafter, it is simulated how the moire pattern M shown in FIG. 4 changes depending on the positional deviation other than the roll rotation. Accordingly, FIGS. 5 to 9 shown below all assume a state in which the luminance modulation light valve 80 is rotated by 0.5 ° in the roll direction.
First, while observing the distortion state of the moire pattern, the working distance of the relay lens 60 (the distance from the color modulation light valve 40 to the relay lens 60, hereinafter abbreviated as WD) is adjusted. (Step S2 in FIG. 2, optical axis direction position adjusting step).
Although the WD shift of the relay lens affects various aberration characteristics, the inventor has focused attention on the influence on the distortion aberration. Even if the WD slightly deviates from the appropriate value, the distortion aberration changes, and the moire pattern also changes accordingly. FIG. 5 shows a moire pattern M when WD is set to an appropriate value +1.2 mm. As shown in this figure, it can be seen that the moiré fringes are greatly distorted when the WD shifts. Although illustration is omitted, the present inventor has confirmed the moire pattern under this condition even in an actual optical system, which is in good agreement with the simulation result.
That is, if the moire pattern is distorted as shown in FIG. 5, the WD of the relay lens 60 is adjusted until the distortion becomes the smallest to bring it closer to the ideal state of FIG.

Next, while observing the inclination state of the moire pattern, the paraxial magnification of the relay lens 60 is adjusted so that the inclination is minimized (step S3 in FIG. 2, relay magnification adjustment step).
The inventor has paid attention to the fact that the inclination of the moire fringes changes greatly with a slight change in the paraxial magnification of the relay lens. 6 shows the relay lens paraxial magnification of 0.999 times, FIG. 7 shows the relay lens paraxial magnification of 1.000 times (appropriate value), and FIG. 8 shows the relay lens paraxial magnification of 1.001 times. A moire pattern M when set is shown. As shown in these figures, it can be seen that when the paraxial magnification of the relay lens deviates from an appropriate value, moire fringes are greatly inclined.
That is, if the moire pattern is tilted as shown in FIGS. 6 and 8, the paraxial magnification of the relay lens 60 is adjusted until the tilt becomes the smallest as shown in FIG.
When the original ideal set magnification is 0.999 times, the paraxial magnification may be adjusted so as to approach the inclination of the moire fringes in FIG.
The paraxial magnification adjustment described above is performed by adjusting a predetermined lens interval inside the relay lens 60. As the predetermined lens interval, an interval at which the magnification can be easily changed is selected while the influence on the imaging performance is small even if the interval is changed. The relay lens 60 is provided with an adjustment ring for that purpose.

Next, while observing the size and position of the area where the moire pattern can be clearly seen, adjust the rotational position of the brightness modulation light valve 80 in the yow direction and the rotational position in the pitch direction, so that the moire pattern is entirely displayed on the entire screen. (Step S4 in FIG. 2, parallelism adjustment step).
For example, if the luminance modulation light valve 80 is rotated (shifted) from the appropriate position in the pitch direction, the image of the color modulation light valve 40 is defocused in the vertical direction of the pitch direction, and is in focus at the intermediate position. It becomes a state. As a result, as shown in FIG. 9, for example, the moire pattern is clearly visible near the center of the screen (region: Ma), but is unclear at the top and bottom of the screen (region: Mb). If the luminance modulation light valve 80 is rotated (shifted) from the proper position in the yow direction, the image of the color modulation light valve 40 is defocused on the left and right in the yow direction. For example, near the center of the screen. It looks clear, but it is unclear on the left and right sides of the screen.
Accordingly, the brightness modulation light valve 80 is rotated in the yow direction or the pitch direction while observing the distribution of the visibility of the moiré pattern in the screen and the direction in which the distribution moves. Adjust the rotation position in the yow direction or the pitch direction until the visibility distribution is as uniform as possible.

Next, the rotational position in the roll direction of the luminance modulation light valve 80 is adjusted so that the moire pattern is not visible (step S5 in FIG. 2, rotational relative position adjustment step).
Since the proper position of the luminance modulation light valve is already known in the simulation, the moire can be eliminated by simply returning the luminance modulation light valve rotated by 0.5 ° in the roll direction in step S1. On the other hand, in an actual optical system, the luminance modulation light valve may be rotated in the roll direction to a position where the moiré pattern is most difficult to see. As a result, there may be a case where it is necessary to rotate the luminance modulation light valve in the roll direction, for example, more than the angle rotated in step S1.

Finally, when the moire disappears, the horizontal and vertical adjustment patterns are displayed on the color modulation light valve 40 and the luminance modulation light valve 80, respectively, while the horizontal direction (x direction) of the color modulation light valve 40 and the luminance modulation light valve 80 is displayed. ) Position and vertical position (y direction) are respectively adjusted (step S6 in FIG. 2, horizontal / vertical position adjusting step).
Thus, the alignment between the color modulation light valve 40 and the luminance modulation light valve 80 is completed.

  The position adjustment method of the color modulation light valve 40 and the luminance modulation light valve 80 of the present embodiment is such that a state in which a lot of moire is intentionally generated by rotating the luminance modulation light valve 80 in the roll direction is prepared. The WD and magnification of the relay lens 60, the in-plane rotation positions and the parallelism of the color modulation light valve 40 and the luminance modulation light valve 80, and the like are adjusted while observing the change state of the moire pattern. By observing the change state of the moire pattern, it is possible to accurately adjust the parallelism, which has been difficult in the past, so that the color modulation light valve 40 and the luminance modulation light valve 80 are aligned with high accuracy. can do.

  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 configuration of each optical system of the projection type image display apparatus exemplified in the above embodiment can be appropriately changed. Further, the example of adjusting by moving the relay lens in the optical axis direction and the example of adjusting by rotating the luminance modulation light valve have been described, but between the three optical systems of the color modulation light valve, the relay lens, and the luminance modulation light valve. Therefore, other than the above example, for example, a method of adjusting the color modulation light valve or the luminance modulation light valve by moving the color modulation light valve in the optical axis direction or rotating the color modulation light valve may be used. . Further, when adjusting the position of the light valve, the position of the light valve may be adjusted in a state in which the polarizer on the incident / exit side is integrated with the light valve.

It is a top view which shows schematic structure of the projection type display apparatus of one Embodiment of this invention. It is a flowchart which shows the position adjustment method of this embodiment in process order. It is a figure for demonstrating the form of rotation of a brightness modulation light valve. It is a figure which shows the simulation result of a moire when rolling the brightness | luminance modulation light valve. It is a figure which shows the simulation result of a moire when changing WD of a relay lens. It is a figure which shows the simulation result of a moire when changing the magnification of a relay lens. It is a figure which shows the simulation result of a moire when the magnification of a relay lens is an appropriate value. It is a figure which shows the simulation result of a moire when changing the magnification of a relay lens. It is a figure which shows the simulation result of a moire when the brightness | luminance modulation light valve has shifted | deviated to the pitch direction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projection type image display apparatus (projector), 10 ... Light source, 40, 40R, 40G, 40B ... Color modulation light valve (first light modulation element), 60 ... Relay lens (relay optical system), 80 ... Brightness modulation light Valve (second light modulation element), 100... Projection lens.

Claims (4)

A light source and a plurality of pixels whose light propagation characteristics can be independently controlled; a first light modulation element which modulates light emitted from the light source; and a plurality of pixels whose light propagation characteristics can be independently controlled. And a second light modulation element that modulates light emitted from the first light modulation element, and disposed between the first light modulation element and the second light modulation element. A relay optical system that forms an optical image on the second light modulation element; and a method for adjusting the position of the first light modulation element and the second light modulation element in an image display device comprising:
By observing a change in moire pattern while shifting the relative positions of the first light modulation element, the relay optical system, and the second light modulation element in the optical axis direction, the first light modulation element and the relay optical An optical axis direction position adjusting step for adjusting a relative position of the system and the second light modulation element in the optical axis direction;
After the optical axis direction position adjusting step, by observing a change in the moire pattern while shifting the relative position between the first light modulation element and the second light modulation element, the first light modulation element and the second light modulation element A parallelism adjustment step of adjusting the parallelism with the second light modulation element;
After the parallelism adjustment step, the first light modulation element and the second light modulation element are eliminated by eliminating the moire while shifting the rotational relative positions of the first light modulation element and the second light modulation element. A rotation relative position adjustment step for adjusting the rotation relative position of
A method for adjusting the position of the first light modulation element and the second light modulation element in the image display device.   Before the optical axis direction position adjusting step, a moire pattern increasing step of increasing the number of appearance of the moire pattern by shifting the rotational relative positions of the first light modulating element and the second light modulating element The position adjustment method of the 1st light modulation element and the 2nd light modulation element in the image display apparatus of Claim 1 characterized by the above-mentioned.   After the optical axis direction position adjustment step, further comprising a relay magnification adjustment step of adjusting the magnification of the relay optical system by observing a change in the moire pattern while shifting the magnification of the relay optical system. The position adjustment method of the 1st light modulation element and the 2nd light modulation element in the image display apparatus of Claim 1 or 2 characterized by the above-mentioned.   After the rotation relative position adjustment step, a horizontal / vertical adjustment pattern is displayed on each of the first light modulation element and the second light modulation element, and the first light modulation element, the second light modulation element, The first light modulation element and the second light modulation in the image display device according to claim 1, further comprising a horizontal / vertical position adjustment step of adjusting a horizontal / vertical position of the image display device. Element position adjustment method.

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