JP4591751B2 - Image projection system and image projection apparatus - Google Patents

Description

  The present invention relates to a technique for reducing luminance unevenness and color unevenness of a display image in application to a system that displays an image using a plurality of projectors.

  In a multi-projection system using a plurality of projector devices, a form (so-called tiling) in which projection images (patch images) by the projector devices are combined vertically and horizontally and displayed on one large screen, and projections by a plurality of projector devices There is a known format (so-called stacking) in which images are superimposed and displayed at the same place (see, for example, Patent Document 1).

  In addition, a projector device using a light modulation element for image display of a one-dimensional spatial modulation type is known. For example, a grating light valve developed by Silicon Light Machine (SLM) of the United States is described below. , “GLV”), which includes a reflective diffraction grating, and a plurality of movable ribbons are arranged at a predetermined interval, and a fixed ribbon is arranged between adjacent movable ribbons. Then, by applying a drive voltage between the common electrode and the movable ribbon, the movable ribbon moves, and a diffraction grating for incident light is configured. A one-dimensional image is formed by a laser beam modulated using a GLV element, and a two-dimensional image can be formed by projecting an image on a screen using an optical scanning unit such as a galvanometer scanner and a projection lens.

  By the way, if each projection image obtained by a plurality of projectors has luminance unevenness or color unevenness, the uniformity of the composite image at the time of stacking is impaired, resulting in a decrease in image quality. A method of individually calibrating uneven luminance and uneven color for each projector is employed.

  FIG. 21 is a diagram for explaining conventional color unevenness correction, and shows illumination light profiles (luminance distribution) before and after calibration using two projectors “A” and “B” as an example.

  The upper left figure (a) shows a distribution example before calibration relating to the projector A, and the figure (A) located on the right side of the figure shows an example distribution after calibration concerning the projector A.

  Also, the lower left (b) diagram shows an example of the distribution before calibration related to the projector B, and the (B) diagram located on the right side of the diagram shows an example of the distribution after calibration related to the projector B.

  And the (C) figure located in the right end has shown the example of distribution after a calibration at the time of stacking using the projectors A and B. FIG.

  In each figure, the horizontal axis indicates the pixel position in the long axis direction of the one-dimensional light modulation element, and the vertical axis indicates the luminance (intensity). Further, in FIGS. 4A and 4B, “Gc” (c = r, g, b) indicates the intensity distribution of each color illumination light of R (red), G (green), and B (blue). ("C" is an index for distinguishing the difference in color and represents one of red (r), green (g), and blue (b)).

  First, in projector A, as shown in (a), green light has the lowest value among red (see Gr), green (see Gg), and blue (see Gb). For example, for red light and blue light, the luminous flux value at the lowest luminance is 4000 lm (lumen), whereas the luminous flux value at the lowest luminance of the green light is 3000 lm.

  Therefore, a distribution uniformized to 3000 lm is obtained by calibration as shown in FIG. That is, in projector A, the maximum white brightness that can be achieved is limited by the minimum brightness of green light.

  In the projector B, blue light (see Gb) shows the lowest value as shown in FIG. For example, the minimum value of red light is 3500 lm and the minimum value of green light is 4000 lm, whereas the minimum value of blue light is 3000 lm.

  Therefore, a uniform distribution of 3000 lm is obtained by calibration as shown in FIG. That is, in projector B, the maximum brightness of white that can be realized is limited by the minimum brightness of blue light.

  When projectors A and B are used, as shown in FIG. 6C, a luminance distribution that is uniformized to 3000 + 3000 = 6000 lm is obtained as an illumination profile after calibration by combining the two.

JP 2001-249652 A

  In the form of correcting individual color unevenness for each projector apparatus as described above, it is a problem that the light source light flux cannot be used effectively.

  This is because the intensity distribution in stacking is determined depending on the illumination profile of each device, and therefore the sum of the minimum luminance values for each device cannot be exceeded.

  The example of FIG. 21 described above will be described. In the figure in which (a) and (b) are combined in the entire system including projector A and projector B, the minimum value regarding the total value of red light is 4000 + 3500 = 7500 lm. It is. Similarly, the minimum value of green light (total value) is 3000 + 4000 = 7000 lm, and the minimum value of blue light (total value) is 4000 + 3000 = 7000 lm. Therefore, the minimum luminance of the three parties is determined by the minimum value of green light and blue light, and is set to 7000 lm. That is, although the room of 1000 lm is left as compared with 6000 lm, the light flux is not used for image display in the above configuration. The illumination light to the one-dimensional light modulation element is finally reflected in the illumination state on the screen via the optical system. However, as a result of giving priority to the uniformity of the light, the luminous flux utilization rate is sacrificed.

  In view of this, the present invention sufficiently reduces brightness unevenness, color unevenness, and the like of a display image when a plurality of projector devices are used to superimpose and display projection images from the respective devices, and for that reason, the luminous flux utilization factor is reduced. It is an issue to avoid a decrease.

  In order to solve the above-described problem, the image projection system of the present invention measures information of an illumination profile indicating the intensity distribution of each color light source in the image projection apparatus for each image projection apparatus, and each measurement information for each light source color. Calculate the illumination profile of the entire projection light synthesized by adding each, and change the illumination profile for each image projection device based on the lowest value of light intensity calculated by comparing the illumination profiles for each light source color Correction profile information is sent to each image projection apparatus.

  In addition, the image projection apparatus according to the present invention has a configuration shown in the following (1) or (2) in an image projection mode in which display images are generated by superimposing respective projection images in cooperation with other image projection apparatuses.

  (1) The illumination profile information indicating the intensity distribution of each color light source is measured, and the illumination profile of the entire projection light combined as a total with the illumination profile measurement information of each color light source constituting another image projection apparatus is calculated. Then, based on the minimum value of the light intensity calculated by comparing the illumination profiles for each light source color, correction profile information for changing the illumination profile for each image projection apparatus, other images as necessary Send to the projection device.

  (2) Measuring illumination profile information indicating the intensity distribution of each color light source and sending the measurement information to another image projection apparatus, and uniforming the light intensity in the illumination profile of the entire projection light that generates a display image by superposition To change the illumination profile of each color light source in accordance with correction profile information sent from another image projection apparatus.

  Therefore, in the above-described invention, color unevenness and luminance unevenness are not corrected one by one for each image projection apparatus, but the total illumination profile obtained by summing up the illumination profiles for each image projection apparatus for each light source color is calculated. The illumination profile of each image projection device can be corrected so that the light intensity distribution when the projection images for each device are superimposed is made uniform.

  According to the present invention, when projection images from a plurality of image projection apparatuses are superimposed on a screen, the illumination profile is adjusted so that luminance unevenness and color unevenness do not occur in the entire display image, thereby uniformizing the illumination light (Each image projection apparatus may have uneven brightness, etc.). Moreover, as a result of giving priority to the uniformity of illumination light, the luminous flux utilization factor is not sacrificed, and the light source luminous flux can be used effectively.

  In order to make the light intensity uniform in the illumination profile of the entire projected light after superimposition, the profile measurement for calculating the illumination profile of the entire projected light for each light source color by summing up the illumination profiles for each image projection device And a correction profile generation unit that generates correction profile information for each image projection apparatus based on the minimum value of the light intensity. That is, the correction profile of each device is determined with priority given to the uniformity of the entire image formed by superimposing the image projection lights.

  In application to a light scanning means of a one-dimensional image obtained by light modulation using a one-dimensional light modulation element or an image projection apparatus equipped with a projection optical system, the light intensity is controlled by controlling the driving means related to the one-dimensional light modulation element. And a light intensity distribution measuring means for receiving the light emitted from the projection optical system when displaying the measurement image and measuring the intensity distribution in the pixel arrangement direction corresponding to the major axis direction of the one-dimensional light modulation element. Correcting means for equalizing the light intensity in the pixel array direction by correcting the driving signal related to the one-dimensional light modulation element based on the correction profile information and controlling the driving means related to the one-dimensional light modulation element. The provided configuration form is preferable, and thereby high performance and improvement in image quality can be realized.

  In addition, if the correction contents of the illumination profile can be switched between an image projection mode in which projection images from a plurality of image projection apparatuses are displayed in an overlapping manner and an image projection mode in the case where the image projection apparatus is used alone, It is convenient because the mode can be selected. That is, in the single-use image projection mode, another image can be obtained by correcting the drive signal related to the one-dimensional light modulation element based on the measurement data from the light intensity distribution measurement means and controlling the drive means of the element. The light intensity in the pixel array direction can be made uniform according to profile correction independent of the projection device.

  FIG. 1 shows a basic configuration example of an image projection system according to the present invention, and shows a system for generating a display image by superimposing projection images from a plurality of image projection apparatuses.

  In the image composition by stacking, images from two or more image projecting devices are projected on the same place. In the following, for simplification of explanation, two image projecting devices 1_1 and 1_2 are used. A case is assumed in which the projected images of the respective devices are superimposed on the screen “SCN”.

  “D1” and “D2” in the figure indicate measurement signals related to the illumination profiles of the image projection apparatuses 1_1 and 1_2, and these are sent to the profile measurement unit 1a. That is, the image projection device 1_1 corresponds to the projector A described above, the measurement signal D1 is sent to the profile measurement unit 1a, the image projection device 1_2 corresponds to the projector B described above, and the measurement signal D2 corresponds to the profile measurement unit 1a. Sent to. The profile measuring unit 1a is provided to calculate the illumination profile of the entire projection light for each light source color by summing up the illumination profiles for each image projection device, and obtain the illumination profile of the entire projection light synthesized for each color. .

  The correction profile generator 1b generates correction profile information for each image projection device based on the minimum value of the light intensity in order to make the light intensity uniform in the illumination profile of the entire projection light.

  FIG. 2 is an explanatory diagram of color unevenness correction according to the present invention. Note that the wavelengths of the R, G, and B color light sources are the same between the image projection apparatuses 1_1 and 1_2, or the difference between the two is within an allowable error range.

  The upper left (a) diagram shows a distribution example before calibration related to the image projection apparatus 1_1, which is the same as the (a) diagram of FIG.

  Also, the lower left (b) diagram shows a distribution example before calibration for the image projection apparatus 1_2, which is the same as the (b) diagram of FIG.

  The diagrams (a + b) shown on the right side of FIGS. (A) and (b) show distribution examples before calibration when the diagrams (a) and (b) are combined.

  And the figure (c) located in the right end has shown the example of distribution after a calibration at the time of stacking using image projection device 1_1 and 1_2.

  The meanings of the horizontal and vertical axes in each figure and the meaning of “Gc” (c = r, g, b) are as described above.

  In the image projecting apparatus 1_1, as shown in (a), the green light shows a minimum value of 3000 lm, and in the image projecting apparatus 1_2, as shown in (b), the blue light shows a minimum value of 3000 lm.

  The (a + b) diagram shows a total luminance (intensity) distribution for each light source color. For example, a profile related to the image projection apparatus 1_1 is denoted as “Pc_1” (c = r, g, b), and image projection is performed. When a profile related to the device 1_2 is described as “Pc_2” (c = r, g, b), it is expressed using Pc_sum (c = r, g, b) shown in the following equation.

Pr_sum = Pr_1 + Pr_2
Pg_sum = Pg_1 + Pg_2
Pb_sum = Pb_1 + Pb_2
That is, Pc_sum represents the total intensity value for each color distinguished by c = r, g, and b. When the pixel position related to the one-dimensional light modulation element is denoted as “x”, the function “Pc_sum” of x (X) ”.

  In the (a + b) diagram, the minimum value regarding the total value of each color light is as follows.

・ Red light (Gr reference): 7500lm
Green light (Gg reference): 7000 lm
Blue light (Gb reference): 7000 lm.

  Therefore, as shown in FIG. 3C, the minimum luminance of the three is determined by the luminous flux values of green light and blue light. When the luminous flux value at the lowest luminance is denoted as “PT_min”, in this example, PT_min = 7000 lm. The After calibration, the light intensity distribution is made uniform regardless of the pixel position x. That is, color unevenness can be corrected based on the result of combining the illumination profiles for each device for each color, and there is no decrease in the luminous flux utilization rate as in the prior art.

  The correction profile generation unit 1b shown in FIG. 1 obtains “Pc_sum” (c = r, g, b), determines the minimum luminance (PT_min) from the result shown in FIG. Information for correction related to the profile (hereinafter referred to as “correction profile”, referred to as “RefPc_i”. “C” is an index for distinguishing light source colors, and “i” indicates an identification number of the apparatus. ) And sent to the image projection apparatuses 1_1 and 1_2 (note that the specific configuration and control will be described in detail later).

  Although FIG. 1 shows a common form by providing the profile measuring unit 1a and the correction profile generating unit 1b outside the image projecting devices 1_1 and 1_2, the present invention is not limited to this, and the functions of each unit are divided and each device is divided. It may be configured so that necessary information including illumination profile data and the like can be exchanged between apparatuses through wired or wireless communication.

  An image projection apparatus used for an image projection system has, for example, an image projection mode shown below.

(I) Image projection mode (stacking mode) for generating a single display image by superimposing projection images in cooperation with other image projection apparatuses
(II) Image projection mode when each device is used alone.

  In the case of (I) above, the specific image projection apparatus measures the illumination profile information indicating the intensity distribution of each color light source, and combines it with the measurement information of the illumination profile of each color light source constituting the other image projection apparatus. The illumination profile of the entire projected light is calculated. The light intensity minimum value (PT_min) is calculated by comparing the illumination profiles for each of the R, G, and B light source colors, and correction profile information for changing the illumination profile for each image projection apparatus based on this is calculated. If necessary, it is sent to another image projection apparatus.

  The image projection apparatus that has received the correction profile information changes the illumination profile of each color light source in the apparatus according to the correction profile information. Thereby, light intensity can be made uniform in the illumination profile of the whole projection light which produces | generates a display image.

  In the case of (II), profile correction is performed based on the measurement result of the illumination profile information indicating the intensity distribution of the color light source in the apparatus. That is, the light intensity in the pixel array direction is made uniform by correcting the drive signal related to the light modulation element based on the measurement data of the light intensity distribution.

  First, a basic configuration example of each image projection apparatus will be described.

  FIG. 3 shows an outline of the configuration of the image projection apparatus 1_1 (or 1_2). Hereinafter, a configuration in which image generation is performed by modulating laser light using a one-dimensional light modulation element will be described.

  In the optical system of the image projection apparatus, light emitted from the light source 2 reaches the light modulation unit 4 through the illumination optical system 3, and the light modulated here passes through the color synthesis unit 5 and the spatial filter 6 to be an optical scanning unit. Reach 7.

  As the light source 2, for example, laser light sources 2R, 2G, and 2B using a semiconductor laser, a solid-state laser, and the like are provided for each of R, G, and B colors. A laser beam having a wavelength corresponding to each is output.

  The illumination optical system 3 has a function of converting a beam output from each laser light source into a one-dimensional linear beam, and is configured using a beam expansion optical system, a line generator, or the like. Note that optical systems 3R, 3G, and 3B corresponding to the respective colors of R, G, and B are used.

  The light modulation unit 4 is configured by using one-dimensional light modulation elements 4R, 4G, and 4B corresponding to R, G, and B colors, and a profile (so-called so-called profile) that is substantially uniformized through the optical systems 3R, 3G, and 3B. Each element is irradiated with a linear beam having a “top hat” distribution.

  In an application example using a GLV element as a one-dimensional light modulation element, in the case of a reflective diffraction grating, a plurality of movable ribbons and fixed ribbons are alternately arranged along a predetermined direction. For example, when six ribbon elements constituting one pixel are provided and every three movable ribbons and every other fixed ribbon are arranged, 6480 in 1080 pixels for one line. The ribbon elements are arranged along a one-dimensional direction (major axis direction). For the first surface, which is the surface of the movable ribbon, and the second surface, which is the surface of the fixed ribbon, with respect to the laser light irradiation surface, aluminum copper (AlCu) alloy or the like is used, and each surface is arranged alternately. In addition, the movable ribbon is moved in response to a drive signal from a drive means (13) described later, and the position of the first surface is controlled in a direction along the irradiation direction of the laser beam. That is, the movable ribbon moves with a displacement amount corresponding to the application of the drive voltage corresponding to the image signal, and in this state (so-called pixel on), a reflection diffraction grating for incident light is formed (generation of first-order diffracted light). . Further, in a state where the displacement amount is made uniform with the fixed ribbon without moving the movable ribbon (so-called pixel off), the first-order diffracted light is not generated (only regular reflection with respect to the incident light).

  In this way, the reflected light and diffracted light of the illumination light irradiated on the one-dimensional light modulation element are generated, and the color combining unit 5 combines the modulated color lights and sends them to the spatial filter 6.

  The spatial filter 6 has a function of selecting a diffracted light component of a specific order, and in this example, a schlieren filter is used to extract ± first-order diffracted light from light modulated using a one-dimensional light modulation element. (0th-order light not used for image display is shielded).

  For example, a galvanometer is used for the optical scanning unit 7 at the next stage, and receives a one-dimensional image of incident light to form a two-dimensional intermediate image. That is, when the formation direction of the one-dimensional image is the “first direction”, the direction corresponds to the major axis direction of the one-dimensional light modulation element, and the “second direction” is orthogonal to the first direction. A two-dimensional intermediate image is formed by performing optical scanning along the “direction of”. Note that the scanning method includes a unidirectional scanning method and a bidirectional scanning method. In the former method, for example, the left edge of the display screen is set as the scanning start position, the right edge is set as the scanning end position, and the vertical line extending in the first direction from the left edge is started. After scanning along the second direction, when the right edge is reached, the light returns to the left edge again and the optical scanning is repeated. In the latter method, the left edge and the right edge of the display screen are set as the scanning start position and the scanning end position. For example, optical scanning is started from the left edge, and the vertical line extending in the first direction is the first line. After scanning along the two directions, when the right edge is reached, light scanning is performed in the opposite direction, and when the original left edge is reached, the light scanning is started again from the left edge.

  A two-dimensional intermediate image obtained by such optical scanning passes through the light diffusing unit 8 and is then projected onto the screen “SCN” by the projection optical system 9 to display an image.

  The light diffusing unit 8 is provided to obtain diffused light using a diffuser for reducing speckle noise and the like, and the projection optical system 9 is a two-dimensional projection optical system including a projection lens. .

  A light detection device 10 is provided for the projection optical system 9 to detect the light intensity by receiving the light emitted from the projection optical system.

  Next, an image processing system and a control system will be described.

  The video signal indicated by “VIDEO” in the figure is sent to the correction processing unit 12 via the signal processing unit 11.

  In the signal processing unit 11, the video signal is converted from a color difference signal to an RGB color signal. When a nonlinear characteristic such as a γ (gamma) characteristic is given, the color space is converted to the linear characteristic by performing reverse correction, and then the color space is used for the color reproduction range of the illumination light source. Perform the conversion process.

  The correction processing unit 12 performs signal correction with reference to information from a correction data calculation unit (16) described later, and controls a drive signal to the one-dimensional light modulation element generated according to the video signal. To do.

  The drive means 13 is provided to drive the one-dimensional light modulation elements 4R, 4G, 4B, includes an element drive circuit, generates a drive signal in accordance with a command from the correction processing section 12, and generates the light modulation section. 4 one-dimensional light modulation elements. The laser light of each color is modulated by driving control of the light modulation element by the driving unit 13.

  The light intensity distribution measurement processing unit 14 is provided to process the detection information from the light detection device 10 and measure the light intensity distribution in the major axis direction of the one-dimensional light modulation element, that is, the pixel array direction. The light intensity distribution measuring means 15 is configured together with the light detection device 10. That is, the intensity distribution is measured by receiving the light emitted from the projection optical system 9 and the measurement result is sent to the correction data calculation unit 16.

  The optical scanning control unit 17 constitutes an optical scanning unit 18 together with the optical scanning unit 7, and performs control for scanning a one-dimensional image obtained by modulating light using a one-dimensional light modulation element. That is, a control signal is sent to the optical scanning unit 7 in accordance with a synchronization signal indicated by “SYNC” in the drawing and a command from the light intensity distribution measurement processing unit 14 (an optical scanning position instruction signal), and its operation (rotation of the galvanometer mirror) ) To control. Incidentally, for the synchronous control of the drive timing of the one-dimensional light modulation elements 4R, 4G, 4B and the rotation phase (light scanning position) of the galvano mirror constituting the light scanning unit 7, known control means using a CPU is used. Is under the control of

  In this example, the correction data calculation unit 16 constitutes the correction unit 20 together with the storage unit 19 and the correction processing unit 12 and is realized using hardware such as a CPU (Central Processing Unit) and a memory and a processing program. . That is, the correction unit 20 corrects the drive signal related to the one-dimensional light modulation element based on the measurement data from the light intensity distribution measurement processing unit 14. Although the correction method will be described in detail later, correction for making the light intensity uniform is performed by controlling the driving means 13.

  The correction data calculated based on the measurement data sent from the light intensity distribution measuring means 15 to the correction data calculating unit 16 is sent to the correction processing unit 12 for reference.

  When displaying a light intensity measurement image and performing measurement by the light intensity distribution measuring means 15, for example, as a preparation stage before image projection, the measurement image is output from the projection optical system 9 at the stage of calibration or the like. And the form detected with the photon detection apparatus 10 is mentioned. Alternatively, a form in which a measurement image is output from the projection optical system 9 and detected by the light detection device 10 so as not to adversely affect the image display while performing image projection is also possible.

  FIG. 4 is a schematic view illustrating the main part of the optical system according to the image projection apparatus.

  The one-dimensional light modulation elements 4R, 4G, and 4B corresponding to the colors R, G, and B are respectively irradiated with linear beams from an illumination light source (not shown).

  The modulated laser beams are optically combined using the color combining mirrors 21 and 22, and then reach the galvano scanner 26 via the Offner relay system 23 and undergo optical scanning.

  The Offner relay system 23 is composed of a primary mirror (concave mirror) 24 and a secondary mirror (convex mirror) 25. The light after color synthesis is first reflected by the primary mirror 24 and then the secondary mirror. After being reflected by the main mirror 24 and further reflected by the main mirror 24, the light is emitted toward the galvano scanner 26. By providing the secondary mirror 25 with the function of a Schlieren filter (the function of separating the specularly reflected light component and the diffracted light component and extracting only the diffracted light of a specific order) or attaching the Schlieren filter to the secondary mirror 25 The 1st-order diffracted light and the 0th-order diffracted light can be separated and the 1st-order diffracted light can be selected and passed. This embodiment has a simple optical configuration, is suitable for downsizing, and is effective for reducing aberrations.

  The formation direction of the one-dimensional image reaching the galvano scanner 26 from the Offner relay system 23 is a direction perpendicular to the paper surface of FIG. 4, and a two-dimensional intermediate image “g2” is formed by optical scanning. In this example, a field curvature correcting optical system 27 is disposed after the galvano scanner 26 in order to remove the field curvature of the two-dimensional image. In this example, the image projection is performed after the optical scanning, but the optical scanning unit may be arranged in the subsequent stage of the projection optical system.

  The two-dimensional intermediate image g2 after the field curvature correction is enlarged and projected on the screen by the projection optical system 9, and the measuring device 28 is used to measure the light intensity distribution. This measuring device 28 constitutes the light detecting device 10 of the light intensity distribution measuring means 15 described above, and is located in the vicinity of the exit of the projection optical system 9 and after condensing the emitted light from the projection optical system 9. Detect the averaged light intensity.

  In this example, the optical element 29 for condensing, the integrating sphere 30, and the light detecting means 31 are provided, and the emitted light from the projection optical system 9 is condensed by the optical element 29 and introduced into the integrating sphere 30, The light detection means 31 detects the light intensity averaged by the integrating sphere 30.

  The optical element 29 using a condensing lens such as a Fresnel lens has a function of condensing all the light emitted from the projection lens and re-imaging it.

  The laser beam condensed by the optical element 29 is introduced from an opening (not shown) formed in the integrating sphere 30, and the light intensity in the integrating sphere 30 is made uniform by multiple reflection inside. That is, the integrating sphere 30 constitutes an averaging means, and the averaged light intensity is detected by the light detection means 31.

  The light sensor constituting the light detection means 31 converts the light reception signal into an electrical signal and outputs it, and the detection signal is used as basic data for light intensity distribution measurement (sent to the light intensity distribution measurement processing unit 14 for processing). .)

  As an installation form of the measurement device 28, for example, in a configuration form in which the measurement device can be attached to the main body of the image generation device, the measurement device is used only in the measurement of the light intensity distribution using the measurement image. The structure which installed and enabled it to remove a measuring apparatus after this measurement is mentioned. Further, in a configuration in which the positioning control of the measuring device can be performed using a moving means such as a movable stage, the projection optical system is moved by moving the measuring device 28 to a position near the projection optical system 9 when measuring the light intensity distribution. 9 light beams can be introduced into the integrating sphere 30 in the measuring device 28. Note that it is necessary to move the measuring device 28 to a retracted position that does not affect the display during image projection.

  In the one-dimensional light modulation element, the number of measurements corresponding to the number of pixels in the major axis direction is performed. For example, in the case of a GLV element having a 1080 pixel array in the one-dimensional direction, the measurement starts from the first pixel. Thus, up to the 1080th pixel, each pixel is individually turned on (pixel-on state) and the process of recording the output of the photosensor is sequentially performed to collect measurement data. Thereby, independent light intensity measurement is possible for each pixel. In order to collect two-dimensional measurement data including a direction orthogonal to the pixel array direction, the same measurement as described above may be performed while changing the optical scanning position by controlling the operation of the galvano scanner 26 (for example, movable (The position of the integrating sphere 30 and the optical sensor is controlled by moving the stage, etc.).

  Next, based on the measurement data of the light intensity distribution obtained by the above measurement, the drive signal related to the one-dimensional light modulation element is corrected, and intensity unevenness and color unevenness (irradiation light distribution non-uniformity) are removed. Processing will be described.

  Hereinafter, a correction process related to the pixel arrangement direction corresponding to the long axis direction of the one-dimensional light modulation element will be described. This correction is required for factors such as variations in the characteristics of the one-dimensional light modulation element, the characteristics of the drive circuit, etc., and the unevenness of illumination light due to ambient temperature, changes with time, and the like. That is, if there is no variation in the modulation characteristics of the constituent elements corresponding to each pixel in the one-dimensional light modulation element to be used, and the situation in which the illumination light for the one-dimensional light modulation element is uniform always holds, the image signal It is possible to display an ideal image by controlling the driving of the element according to the above. However, actual one-dimensional light modulation elements have variations in characteristics of the elements themselves due to manufacturing accuracy and the like, variations in characteristics related to the drive circuit of the elements, and the like.

  FIG. 5 illustrates a GLV element 32 as a one-dimensional light modulation element. Three fixed ribbons Rs, Rs,... And movable ribbons Rm, Rm,. One pixel is formed as a set. That is, for the number of pixels required for GLV along the ribbon width direction, for example, 1080 pixels, a spatial modulation element is configured by arranging 6480 ribbons along the one-dimensional direction.

  FIG. 5A illustrates a state in which positional variation of the ribbon occurs when no driving voltage is applied. As indicated by “Δh1” and “Δh2” in the figure (the amount of deviation is exaggerated in the figure), since the movable ribbon Rm is deviated from the position where it should originally be located, Variation) is a problem. In other words, when there is no relative displacement between the movable ribbon and the fixed ribbon, when the illumination light is incident on the GLV, the diffracted light is not generated only by regular reflection, so the illuminance on the screen is It becomes the lowest level (for example, black level). However, when diffracted light is generated due to the irregularity of the ribbon position, it is displayed at an unintended brightness level according to the position error of the movable ribbon. If this appears in the form of stripes in the scanning direction (horizontal direction) along with the optical scanning, there is a risk that the contrast of the screen will be lowered.

  FIG. 5B shows a state when a certain drive voltage is applied, and the diffraction grating is formed by moving the movable ribbon relative to the fixed ribbon.

  The position of the movable ribbon group should be essentially the same for the same drive voltage, but in this example, as shown by “ΔH1” and “ΔH2” in the figure, the movable ribbon Rm is displaced (see FIG. Shows the amount of displacement in an exaggerated manner.)

  In a configuration in which a GLV in which a plurality of movable ribbons and fixed ribbons are alternately arranged is arranged on a one-dimensional array, the reflective surface of the movable ribbon is moved relative to the reflective surface of the fixed ribbon by controlling voltage application. Therefore, when the irregularity of the ribbon position described above is remarkable, there is a possibility that the brightness and the hue are varied on the screen and the image quality is deteriorated.

  In this example, each of the movable ribbon and the fixed ribbon has a configuration in which the reflecting surface surfaces thereof have a parallel relationship with each other, but each reflecting surface has its reference surface (for example, a GLV element). A structure arranged so as to be inclined at a predetermined angle from a plane parallel to the substrate surface (so-called blazed GLV. When the wavelength of incident light is denoted as “λ”, each of the ribbon groups arranged in parallel on one plane and the other Only the first-order diffracted light is emitted by operating so that the optical path difference between the ribbons arranged in parallel on one plane becomes λ / 2.) However, the variation in the ribbon position is also a problem as described above. .

  (B) The ribbon misalignment in the figure has a complicated aspect when the variation in the characteristics of the drive circuit is further added in addition to the variation in the manufacturing of the ribbon element itself.

  In addition, when obtaining illumination light to a one-dimensional light modulation element using a laser light source, a uniform brightness intensity distribution (so-called “top hat shape”) in a one-dimensional direction is required as an illumination profile. However, when the lighting conditions are affected by the secular change or the like, the brightness on the screen and the nonuniformity of the color display are caused. For example, even when using a monochromatic light source, it is difficult to obtain uniform illumination light with sufficient accuracy, and it is difficult to always achieve uniform illumination light for all laser light sources having different wavelengths for each of the three primary colors. is there.

  Therefore, in order to detect the light intensity, considering that the modulation characteristics related to the one-dimensional light modulation element and the influence of the illumination profile of the one-dimensional light modulation element are reflected in the intensity of the light forming the one-dimensional image. Measurement is performed using the measuring device 28. Among the measurement data, the data in the one-dimensional direction corresponding to the major axis direction of the one-dimensional light modulation element represents the luminance and color non-uniformity (deviation from the uniform state) at each pixel position. Can be corrected to eliminate non-uniformity (in other words, instead of using the measured value of the light intensity distribution, correction using the distribution characteristics known from the design value, simulation results, etc. is also possible. Although it is conceivable, a correction process based on actually measured data is desirable when taking into account changes with time of the laser light source or the like.

  When the image projection apparatus is used alone as in (II) above, the correction means 20 corrects the drive signal related to the one-dimensional light modulation element based on the measurement data from the light intensity distribution measurement means 15. Then, the light intensity in the pixel array direction is made uniform (reduction in intensity unevenness) by the control of the driving unit 13 according to the corrected driving signal.

  The outline of the processing is as follows.

(S1) Measure the display brightness and color non-uniformity. (S2) Calculate the correction data of the drive control related to the one-dimensional light modulation element from the measurement data of (S1). The drive signal correction control for the one-dimensional light modulation element is performed using the data.

  In (S1), for example, light from each laser light source is sequentially irradiated onto the corresponding one-dimensional light modulation element, and each element (for example, one pixel) constituting each pixel in the one-dimensional light modulation element. (A ribbon group) is supplied with a drive signal (test signal) for displaying a measurement image, and the light intensity of each element is measured. For example, in the case of a GLV element, gradation display can be controlled by changing the drive voltage stepwise from the minimum voltage to the maximum voltage, so that the illumination light is modulated according to the level of each drive voltage (gradation step). You can know the light intensity when.

  Further, in (S2), data that is individually measured according to the difference in pixel position and gradation is data (ideal data or data that should be originally obtained when there is no variation in modulation characteristics). Reference data) and compare. As a result, it is possible to grasp the calculation of the correction data, that is, how much correction should be performed to set the actual light intensity to a predetermined value (or specified value).

  In (S3), the drive signal is actually supplied to the one-dimensional light modulation element to operate by using the calculated correction data.

  In the following, first, the overall influence is measured by the measuring device 28 without distinguishing between the influence on the intensity distribution due to the modulation characteristic of the one-dimensional light modulation element and the influence on the intensity distribution due to the change of the illumination condition or the like. A form when it is assumed that it is reflected in the data will be described.

  An example procedure for intensity distribution measurement is as follows.

(S1-a) Preparation for measurement (position setting of measuring device 28, etc.)
(S1-b) Turning on the light source (S1-c) Measuring modulation characteristics (S1-d) Turning off the light source (S1-e) Switching to another light source (S1-b), (S1-c), ( Repeat the procedure of S1-d).

  First, the positioning of the measuring device 28 is performed in (S1-a).

  In (S1-b), when the laser light source is turned on, the linear beam that has passed through the illumination optical system illuminates the one-dimensional light modulation element corresponding to the light source.

  In (S1-c), the modulation characteristics of the constituent elements of each pixel, that is, the luminance characteristics of the modulated light with respect to the drive voltage are measured for all pixel positions related to the one-dimensional light modulation element.

  FIG. 6 is a diagram for explaining the drive signal voltage “DV” applied to the constituent elements of the one-dimensional light modulator to display the measurement image and the output “PV” of the photosensor constituting the photodetecting means 31. FIG. In addition, time “t” is taken on the horizontal axis, “DV” is shown on the vertical axis in FIG. (A), “PV” is shown on the vertical axis in FIG. Shown as a relative value.

  In this example, the test signal used for displaying the measurement image is a driving voltage (triangular wave quantized) in which the level (relative value) of DV changes to the right when the DV level is 0, 1,. A driving voltage corresponding to each level is applied to the component to be measured and driven. The intensity of the laser beam thus modulated is measured after being introduced from the projection optical system 9 into the measuring device 28 as described above.

  (A) As shown in the figure, the drive voltage of the test signal is stepped so as to change with a constant increment as time passes, whereas the intensity change of the modulated light does not show a linear characteristic, as shown in the figure. In the low drive voltage range, the intensity is zero, and when the drive voltage exceeds a certain value (threshold value), the intensity does not become zero and increases rapidly.

  Since the measurement of such modulation characteristics is performed in the same manner as described above for each pixel position, a number of data equal to the product of the number of pixels and the number of gradation levels of DV is collected.

  In the above example, the laser light source is switched and the above processing is performed individually. For example, after all the R, G, and B laser light sources are turned on, the wavelength-separated intensity for each color is used. In the configuration form in which measurement is possible, switching of the laser light source is unnecessary and processing time is fast.

  In the case of assuming a monochromatic light source, intensity distribution data with the pixel position and gradation level (drive voltage) as variables can be acquired, so that the data is prepared in advance with reference data (ideal values and design target values). By comparison, correction data for element driving can be easily obtained. This is because the degree of excess or deficiency of the drive voltage of each gradation at a certain pixel position can be grasped based on actual distribution data (for example, when the intensity is insufficient, the drive voltage is corrected in a direction to compensate for the deficiency). Just do it.)

  However, in the case of color display, since it is necessary to consider not only the brightness but also the color reproducibility, etc., it is somewhat complicated, and the uniformity that ignores the relationship between colors is insufficient.

  FIG. 7 schematically shows an illumination profile for each color, with the horizontal axis representing the pixel position and the vertical axis representing the optical sensor output (relative value).

  When a specific drive voltage (DV) in the test signal is applied to the element and the intensity distribution at each pixel position is measured, “Ic” (c = r, g, b) in the figure indicates the illumination profile (FIG. Shows exaggerated strength non-uniformity.)

  Since the intensity distribution of modulated light is governed by various factors such as variations in modulation characteristics and profile variations due to lighting conditions, it is virtually impossible to perfectly match the intensity distribution of modulated light of each color. This is obvious when considering the influence of environmental changes such as aging and temperature.

  Therefore, correction processing is performed according to the following procedure.

(S2-a) Conversion to luminance value related to modulation characteristic (S2-b) Calculation of maximum white luminance (S2-c) Calculation of target modulation characteristic (S2-d) Calculation of correction data.

  Each illumination profile “Ic” (c = r, g, b) in FIG. 7 is obtained as an output (voltage value) of the optical sensor, and a parameter representing the drive voltage DV is denoted as “v”, and the one-dimensional direction (element When a parameter representing a pixel position in the major axis direction of (x) is written as “x”, it can be expressed by using both functions “Ic (v, x)” (c = r, g, b). For example, based on the data shown in FIG. 6, the characteristic “Ic (v, x1)” when the pixel position x is fixed at a specific position “x = x1” when a certain laser light source is used can be obtained. Each “Ic” in FIG. 7 represents a characteristic obtained by changing the pixel position x in the one-dimensional direction when v is fixed to a predetermined value.

  First, in (S2-a), the data (voltage value) represented by Ic (v, x) is converted into a luminance value.

  Specifically, the mixing ratios Rm, Gm, and Bm of the R, G, and B colors are obtained so that the target white light is obtained, and Ic (v, x) is divided by the respective values.

  The tristimulus values for the three primary colors are R (Xr, Yr, Zr), G (Xg, Yg, Zg), and B (Xb, Yb, Zb), and the white tristimulus values are W (Xw, Yw, Zw), the relationship with Rm, Gm, and Bm is defined as follows:

  That is, a column vector having white tristimulus values as components is represented by the product of a 3 × 3 matrix having R, G, and B tristimulus values as column vectors and a column vector having components as a mixture ratio. Is done.

  R (Xr, Yr, Zr), G (Xg, Yg, Zg), and B (Xb, Yb, Zb) are determined by the laser light source used, and for white, from the color temperature (for example, 6500K) to (Xw , Yw, Zw) is determined, Rm, Gm, and Bm can be calculated by converting the actual numerical value into the formula [1]. For example, as shown in the following equation, an inverse matrix of the above-described 3 × 3 matrix may be obtained and product operation with a vector having white tristimulus values as components may be performed.

  When the luminance is written as “Y”, the mixing amount for each color laser beam for realizing the luminance of “Y = 1” with respect to white having a predetermined color temperature is calculated.

  Therefore, when the white luminance that can be realized when modulated light is mixed is represented by Ywr, Ywg, and Ywb, the following expression is obtained.

  When the optical sensor used for measuring the light intensity has wavelength sensitivity, or when considering measurement efficiency or the like, the luminance conversion coefficient “Kc” (c = r, g) is used as a correction coefficient in consideration of the influence thereof. , B) is multiplied by the above “Ywc” (c = r, g, b) to obtain the following expression.

  IYr, IYg, and IYb indicate, for each light source, white luminance that can be realized when the luminance conversion coefficient is considered.

  FIG. 8 schematically shows IYr, IYg, and IYb with the pixel position (x) on the horizontal axis and the luminance on the vertical axis, and a specific value is not selected as the drive voltage value (v). It is out.

  In this figure, among IYr, IYg, and IYb, since IYb indicates the minimum value “IY0” at a certain pixel position, it can be seen that the maximum white brightness that can be realized is limited by IYb (that is, IYb (Because constraints are imposed on the luminance realization, white luminance larger than IY0 cannot be realized.)

  Here, the v value is fixed, but IYr, IYg, and IYb are functions of v and x (IYc (v, x), where c = r, g, b). A minimum value such as IY0 is searched for the drive voltage value v. As a result, the maximum white luminance (referred to as “IYmax”) is determined in the above (S2-b).

  Next, in (S2-c), a target modulation characteristic, that is, a luminance characteristic with respect to the drive voltage value v (hereinafter referred to as a function “IT (v)” of v) is determined.

  According to the γ characteristic of the image input signal, the ideal modulation characteristic exists in the constituent elements of the one-dimensional light modulation element, and this is expressed by the above-mentioned IT ( v) is “IT (v) = (IYmax) · (IV (v))”.

  FIG. 9 illustrates the target modulation characteristic IT (v), where the horizontal axis represents the drive voltage value v and the vertical axis represents the luminance.

  When the characteristic indicated by IT (v) is called “target modulation characteristic”, for example, the characteristic is examined in advance at the design stage, and a reference table or a calculation formula based on the data is incorporated in the apparatus. A form and a form in which a reference table of data related to the target modulation characteristic, a calculation formula, and the like are incorporated in the apparatus so that the user can specify and select according to the selection of the image signal.

  Next, the correction process (S2-d) performed based on the target modulation characteristic will be described with reference to FIG.

  (A) shown on the left side of FIG. 10 shows the IT (v), but the direction of the drive voltage axis is reversed (leftward) so that the vertical axis (luminance axis) has a mirror image relationship with FIG. Is set. Also, the (B) diagram on the right side shows the modulation characteristics obtained by intensity distribution measurement, with the horizontal drive voltage axis pointing to the right and the vertical axis representing the intensity of the modulated light. As a representative example, the figure shows the characteristic IYc (v, x) at each pixel position for the L pixel, the M pixel, and the N pixel.

  The horizontal axis of the target modulation characteristic IT (v) prepared in advance or designated by the user represents the drive voltage value before correction, for example, the luminance with respect to the value indicated by “Vin” in the figure The value of “Y” is determined.

  (B) In the figure, the horizontal axis represents the corrected drive voltage value, and “Vout_l”, “Vout_m”, and “Vout_n” in the figure represent the drive voltage values with the luminance “Y” as the target luminance. , L pixel, M pixel, and N pixel are shown. That is, the drive voltage value necessary to obtain the target luminance “Y” generally differs depending on the pixel position, and the component element is driven for each pixel of the one-dimensional light modulation element with the drive voltage value corresponding to each pixel position. There is a need.

  In FIG. 11, the horizontal axis represents the drive voltage axis before correction (corresponding to the horizontal axis in FIG. 10A), and the vertical axis represents the corrected drive voltage axis (in FIG. 10B). This corresponds to the horizontal axis.

  Before correction, Vout_l is calculated for the L pixel, Vout_m is calculated for the M pixel, and Vout_n is calculated for the N pixel.

  As described above, for any Vin indicating the drive voltage value before correction, the corrected data can be calculated by calculating the drive voltage value (Vout_l or the like) determined according to the difference in pixel position. For example, the form which calculates | requires the relationship of the correction data according to the pixel position with respect to Vin, and produces those data tables is mentioned. Alternatively, in order to reduce the amount of data and the processing time, not only all correction data corresponding to the drive voltage value and pixel position, but only representative data is stored and estimated by interpolation calculation or the like. Various embodiments such as a form using correction data are possible.

  12 and 13 show a configuration example for realizing the correction processing described above, FIG. 12 shows an outline of the configuration, and FIG. 13 shows a main part of the correction calculation configuration.

  In the configuration example 33 shown in FIG. 12, when the video signal VIDEO is input to the signal processing unit 11, the color signals of the three primary colors are output via the internal inverse γ correction circuit, the color space conversion circuit, etc., and the subsequent data correction is performed. Sent to the unit 34.

  The detection information from the measurement device 28 is sent to the detection signal processing unit 35 and processed by the gain adjustment circuit 35a and the A / D conversion circuit 35b. The gain adjustment circuit 35a is provided for correcting a difference in detection sensitivity of the optical sensor with respect to the detection signal of the modulated light. The A / D conversion circuit 35b converts the gain-adjusted analog signal into a digital signal and sends the data to the measurement data storage unit 34a in the data correction unit 34 for storage. The detection signal processing unit 35 constitutes the light intensity distribution measurement processing unit 14.

  The data correction unit 34 includes a measurement data storage unit 34a, a correction value calculation unit 34b, a data table storage unit 34c, and a selection unit 34d.

  Data measured for the constituent elements of each pixel in the one-dimensional light modulation element is stored in the measurement data storage unit 34a, and the correction value calculation unit 34b performs data for each pixel regarding image display using a test signal for measurement. Is used to obtain the above-described modulation characteristics and derive an illumination profile.

  Then, the correction value calculation unit 34b sends the correction data obtained by performing the processes (S2-a) to (S2-d) to the data table storage unit 34c and stores it in the storage area.

  As described with reference to FIG. 11, the data table storage unit 34 c reads out data stored for correction and outputs a drive signal when a drive signal before correction is received. In this example, the correction data is read with reference to the data table. However, in the mode in which the corrected drive signal is calculated by using an arithmetic process such as an interpolation calculation, the data table storage unit 34c is calculated by an arithmetic processing unit. Replace with.

  The selection unit 34d switches the output from the data table storage unit 34c and the test signal for measurement and sends them to the drive unit 36. That is, the test signal (TEST) is selected when measuring the intensity distribution, and the output of the data table storage unit 34c is selected when displaying an image.

  The output of the selection unit 34d is sent to a light modulation unit using a GLV element after passing through a D / A conversion circuit 36a and a drive circuit 36b of the next stage constituting the drive unit 36. The D / A conversion circuit 36a is provided for converting the digital signal output from the data correction unit 34 into an analog signal, and the drive circuit 36b uses the converted analog signal as an input signal according to the signal voltage. A drive voltage is supplied to the GLV element.

  The control unit 37 performs control of timing, signal switching, and the like by sending control signals to the respective components such as the signal processing unit 11, the data correction unit 34, the detection signal processing unit 35, and the like. It has functions such as turning on / off and performing optical scanning control when measuring the intensity distribution.

  FIG. 13 shows a configuration example of the correction value calculation unit 34b, and includes the following elements (the numbers in parentheses indicate symbols).

・ Voltage-luminance converter (38)
・ Luminance distribution analysis unit (39)
-Ideal modulation characteristic function generator (40)
・ Multiplier (41)
Correction table generation unit (42)
Data table storage unit (43)

  First, each data of the modulation characteristic “Ic (v, x)” (c = r, g, b) relating to the one-dimensional light modulation element is converted in the voltage-luminance conversion unit 38 as described above, and a function of luminance is obtained. “IYc (v, x)” (c = r, g, b) is obtained. The data of this function is sent to the luminance distribution analysis unit 39 for analysis and sent to the correction table generation unit 42.

  The luminance distribution analysis unit 39 determines the maximum white luminance IYmax by searching for the minimum value from the data of IYc (v, x) indicating the luminance distribution with respect to the pixel position as described above.

  Also, the ideal modulation characteristic function generation unit 40 generates the data IV (v) and sends it to the multiplication unit 41.

  The multiplying unit 41 multiplies the IV (v) data by the IYmax data from the luminance distribution analyzing unit 39. That is, the data of the target modulation characteristic IT (v) is calculated and sent to each component 42c (c = r, g, b) of the correction table generator 42.

  Based on the data of IT (v) and the data of IYc (v, x) (c = r, g, b), the correction table generation unit 42 generates the drive signal as described with reference to FIGS. Perform correction processing. The data obtained as a result is sent to each component 43c (c = r, g, b) of the data table storage unit 43 and written in a storage area prepared for each color.

  By the measurement and correction processes described above, the luminance profiles related to the laser light sources of the respective colors are aligned at the same level, and white of the target color temperature can be correctly expressed.

  In this example, the measurement data by the measurement device 28 is acquired and the correction process is performed without distinguishing the influence on the intensity distribution of the modulation characteristic and the illumination profile related to the one-dimensional light modulation element. It is possible to perform a correction process by measuring the influences of the two separately.

  For example, the intensity distribution is measured in advance with respect to the modulation characteristics related to the constituent elements of the one-dimensional light modulation element under the condition that non-uniformity of the illumination light is excluded. For the illumination profile of the laser light source, the intensity distribution is measured before the image display or while displaying the image. Drive signal correction data can be obtained based on such separate measurement results (that is, in the above example, the influence of both is obtained in one measurement, but two times for each cause. Can be divided into measurements).

  For example, the manufacturing error of the GLV element, the characteristic error of the drive circuit, and the like are less affected by the change over time and the temperature change, whereas the illumination conditions related to the light source are greatly affected by the change over time and the temperature change. In other words, the variation in the modulation characteristics of the GLV element is initially measured once or a small number of times, but the subsequent change is small, whereas the change in the illumination condition takes time or the surrounding environment changes. When it changes, it will be necessary to measure each time.

  Therefore, the process of measuring the modulation characteristics of the element is performed in advance so as to discriminate the influence between the two and not to include the influence of the lighting conditions. Employing a method for measuring an illumination profile is effective in reducing the burden of each correction process and the processing time.

  An example procedure is as follows.

(ST1) Measure the modulation characteristics of the one-dimensional light modulation element (ST2) Measure the illumination profile for the one-dimensional light modulation element (ST3) Correction data based on the measurement data obtained in (ST1) and (ST2) (ST4) At the time of image projection, correction control of the drive signal related to the one-dimensional light modulation element is performed using the correction data of (ST3).

  First, in (ST1), the modulation characteristic when the non-uniformity of the illumination light is eliminated for the constituent elements of the one-dimensional light modulation element is measured.

  For example, using a dedicated device 44 as shown in FIG. 14, light from the light source unit 45 including laser light sources (reference light sources) for R, G, and B colors is beam-shaped by the illumination optical system 46, and then the mirror 47 is used. After reflection, the one-dimensional light modulation element (GLV element) is irradiated.

  The illumination optical system 46 is provided to irradiate light for each element targeting the constituent elements of each pixel in the GLV element after making the monochromatic laser light from the light source unit 45 into a spot shape.

  Among the constituent elements of the GLV element, the driving voltage according to the test signal as described above is applied to the element to be irradiated with the beam spot, and the light modulated thereby is reflected by the mirror 48 and then used for imaging. The light reaches the light detector 51 through the lens 49 and the spatial filter 50 and is detected. That is, a specific order of diffracted light, for example, first-order diffracted light, is selected by the spatial filter 50 and received by the optical sensor that constitutes the light detection unit 51.

  The GLV element is mounted on a support device 52 for fixing and adjusting the position of the element, and the position of the element and the illumination light at the time of measurement with reference to the alignment mark provided on the GLV element. The setting status is adjusted.

  In the measurement process, the light intensity distribution is measured for each color light source using the pixel position and the drive voltage value as parameters in the same manner as described above, but with high precision uniformity so that the illumination profile does not affect the target element. The target element is irradiated with the intensity distribution.

  The element for which the measurement of (ST1) has been completed is mounted on the image display device, and the measurement data of each element is stored in a storage area in the device and incorporated in the device.

  Next, in (ST2), for example, in the calibration stage immediately before image display, each laser light source in the image display device is turned on to illuminate the one-dimensional light modulation element. Then, a driving voltage according to the test signal is applied to the constituent elements for each pixel, and the modulated light is measured by the measuring device 28 in the same manner as described above.

  Since the data obtained by this measurement includes the influence of the modulation characteristics related to the constituent elements for each pixel, only the nonuniformity of the illumination profile reflecting the influence of only the laser light source and the illumination optical system of the image display device is included. It cannot be measured. This is because, when the measurement device 28 measures the light modulated after irradiating the one-dimensional light modulation element mounted on the device, it depends on the modulation characteristic (manufacturing error, characteristic error of the drive circuit, etc.) inherent to the element. This is because there is always an inseparable effect due to the variation in ().

  However, in a situation where the drive voltage to the element is increased to the extent that the influence of the modulation characteristics of the component element can be ignored and the light intensity is increased, it is possible to approximately measure the illumination profile.

  For example, the maximum displacement amount of the movable ribbon constituting the GLV element is a quarter of the incident light wavelength λ, and 115 nm for blue in which λ = 460 nm (nanometer). On the other hand, the positional variation of the ribbon surface is at most about several nanometers. When moving the movable ribbon with the maximum or close range of displacement, the surface irregularity of the ribbon itself, errors in the drive signal value, etc. Since the influence caused by is sufficiently small, it can be ignored.

  Therefore, for example, the driving voltage of the test signal as shown in FIG. 6 employs a high gradation level range (240 to 255), and operates by applying a large driving voltage to the element, and the modulated light at that time Is measured, it is possible to obtain measurement data of an illumination profile (that is, an intensity distribution according to the pixel position) that sufficiently eliminates the influence of the modulation characteristics of the element. In practice, in the range where the drive voltage is high in the test signal, the intensity change of the modulated light is not so large with respect to the change of the drive voltage (showing a saturated characteristic), so a predetermined drive voltage range is set. By performing intensity measurement, a representative value for each pixel is obtained for the illumination profile.

  In (ST3), the correction data can be calculated in the same manner as described above after integrating the measurement data on the modulation characteristics of the element and the illumination profile. That is, since the influence on the final image (brightness unevenness, color unevenness, etc.) is a combination of both effects, a comprehensive correction process is required.

  An example of the processing procedure is as follows.

(ST3-a) Calculation of illumination profile (ST3-b) Reading of element-specific modulation characteristic data (ST3-c) Calculation of modulation characteristic including illumination profile (ST3-d) Calculation of maximum white luminance and target modulation characteristic (ST3-e) Calculation of correction table

  First, in (ST3-a), data measured using the measuring device 28 for each one-dimensional light modulation element is obtained. When these are expressed by the function “IQc (v, x)” (c = r, g, b), the maximum value (voltage value) of the light intensity detection data when the element is moved in a large driving voltage range is extracted. At the same time, an illumination profile for each light source is calculated by voltage-luminance conversion (hereinafter referred to as function “Pc (x)” (c = r, g, b)).

  In (ST3-b), data of inherent modulation characteristics (hereinafter referred to as function “ISc (v, x)” (c = r, g, b)) including the element and the drive circuit is obtained. This has been measured in advance as described above for each one-dimensional light modulation element mounted on the image projection apparatus.

  Note that (ST3-a) and (ST3-b) may be reversed.

  In (ST3-c), a modulation characteristic “IYc (v, x)” (c = r, g, b) obtained by combining Pc (x) and ISc (v, x) is calculated. Specifically, “IYc (v, x) = Pc (x) · ISc (v, x)” (c = r, g, b) is obtained by multiplication of both.

  In (ST3-d), the calculated IYc (v, x) is analyzed to calculate the maximum white luminance. For example, as shown in FIG. 15, in IYc (v, x) where v is a certain driving voltage value, the area is divided into a plurality of areas along the x direction (pixel arrangement direction), and a white color that can be realized for each area. A maximum value (hereinafter referred to as a function “IYmax (v, x)”) is determined.

  In the above example, IYmax is a constant value that does not depend on the pixel position x, but the following maximum luminance function can be obtained.

Region 1 (see “REG1” in the figure): IYmax1 (v, x) = a · x + b
Region 2 (see “REG2” in the figure): IYmax2 (v, x) = c
Region 3 (see “REG3” in the figure): IYmax3 (v, x) = − d · x + e
In the above formula, a, b, c, d, and e are constants, and when the v value is fixed, it is represented by a linear function of x in this example. Higher order functions may be used.

  The target modulation characteristic IT (v, x) is obtained by multiplication of the ideal modulation characteristic IV (v) and IYmax (v, x) as described above.

  In (ST3-e), the drive voltage value corrected from Vin can be obtained from IT (v, x) and IYc (v, x) in the same procedure as described above. In this example, the target modulation characteristic is obtained. Note that the pixel position x has a dependency on. That is, in FIG. 10, correction data is calculated using the target modulation characteristics corresponding to the L pixel, M pixel, and N pixel individually.

  In (ST4), a drive signal to the one-dimensional light modulation element is generated from correction data corresponding to the image input signal, and drive control is performed on the constituent elements for each pixel.

  FIG. 16 shows a configuration example of the correction value calculation unit 34b, and the differences from the configuration example shown in FIG. 13 are as follows.

Data of “IQc (v, x)” (c = r, g, b) is input to the voltage-luminance conversion unit 38 and “Pc (x)” (c = r, g, b) indicating an illumination profile Is output and supplied to the multiplier 53c (c = r, g, b), respectively. The data of “ISc (v, x)” (c = r, g, b) is stored in the storage 54. The data is supplied to the multiplier 53c (c = r, g, b), respectively. The outputs of the multiplier 53c (c = r, g, b) are the luminance distribution analyzer 39 and the correction table generator. The luminance distribution analysis unit 39 outputs IYmax (v, x) to the multiplication unit 41 to obtain the target modulation characteristic IT (v, x), and data according to the target modulation characteristic IT (v, x) is obtained. 42c (c = r, g, b).

  The voltage-luminance conversion unit 39 obtains data (voltage value) that does not depend on v by taking out the maximum value of intensity in IQc (v, x) data, and converts Pc (x) into luminance value by conversion to luminance value. Output data. A specific conversion method is as described above.

  The multiplier 53c (c = r, g, b) calculates “IYc (v, x) = Pc (x) · ISc (v, x)” (c = r, g, b).

  The luminance distribution analysis unit 39 analyzes IYc (v, x) data and outputs IYmax (v, x), and the multiplication unit 41 calculates a target modulation characteristic as a product of the ideal modulation characteristic IV (v). The

  The correction table generation unit 42 eliminates the luminance and color non-uniformity of the display image based on the obtained target modulation characteristic IT (v, x) and the actually measured modulation characteristic IYc (v, x). As described above, the drive signal is corrected for each color of the illumination light and according to each pixel position. The correction data obtained in this way is written into the storage area of the data table storage unit 43.

  When image display is performed, the image input signal is received and data in the data table storage unit 43c (c = r, g, b) is referred to, and drive control (correction control) according to the pixel position and the drive signal level of the element is performed. ) Is performed.

  In this embodiment, data related to element-specific modulation characteristics is measured in advance and stored in the storage unit 54, and measurement data of an illumination profile that is easily affected by changes over time, environmental changes, and the like is measured in a timely manner. The data in the correction table can be updated at any time or as necessary.

  In addition, since IYmax can be set for each region divided in the pixel arrangement direction, it is possible to increase the use efficiency related to luminance (for example, in the case where the value of IYmax is uniformly defined regardless of the pixel position, In particular, there is a possibility that the usable range of luminance cannot be used.)

  When the image projection apparatuses 1_1 and 1_2 are used alone, it is possible to remove luminance unevenness and color unevenness by the correction described above. However, as described with reference to FIG. 21, calibration is individually performed for each image projection apparatus. When combining the results, the luminance distribution after calibration for each apparatus is added and totaled, so that the usable light flux in the entire superimposed image by stacking is reduced.

  That is, when the image projection apparatus is used alone and when the image projection apparatus is used in combination with another image projection apparatus, it is necessary to change the color unevenness correction method. As described in 2 above, calibration is performed using a total profile obtained by combining the illumination profiles of each device for each color, and the resulting corrected illumination profile signal for each device is generated. It is desirable to perform drive correction of the modulation element. For example, in the case of an apparatus configured to perform image projection for a plurality of modes, in the mode (II), the measurement process and the correction process described above are performed when the image projection apparatus is used alone, and the mode (I) In the (stacking mode), the following measurement process and correction process are performed.

(SS1) The intensity distribution of each color related to illumination light is measured for each device. (SS2) The brightness (PT_min) is determined by combining the profiles of each color from the measurement data of (SS1), and the illumination profile (correction profile) for each device. (SS3) Based on the correction profile generated in (SS2), the drive control correction data relating to the one-dimensional light modulation element is calculated in each device. (SS4) At the time of image projection (stacking) ( Using the correction data obtained in SS3), correction control of the drive signal related to the one-dimensional light modulation element for each apparatus is performed.

  FIG. 17 is a flowchart illustrating the flow of correction profile generation.

  First, after setting the illumination profile measurement mode in step S1, the illumination profile of each color is measured using the measuring device 28 in the next step S2. In other words, when stacking using n projectors is assumed, when the illumination profile of each color related to the i-th projector is denoted as “Pc_i” (c = r, g, b), i = 1 to n Acquire each measurement data. “Pc_i” is represented by a function “Pc_i (x)” of the pixel position x.

  In the next step S3, it is determined whether or not the measurement has been completed for all the projectors. If the measurement has been completed, the process proceeds to step S4. If there is an unmeasured projector, the process returns to step S2 and the measurement is repeated.

  In step S4, after calculating the total sum of the illumination profiles of the respective colors, that is, “Pc_sum (x)” (c = r, g, b), the process proceeds to the next step S5 to calculate the minimum value “PT_min”. To do.

  In the next step S6, the initial value of i is set to 1 with “Yc (x) = PT_min” (c = r, g, b).

  In the next step S7, the brightness conversion profile “Yc_i” (c = r, g, b) of each color related to the i-th device is subtracted from “Yc (x)” (c = r, g, b). Is a new Yc (x). Then, the i value is incremented (i → i + 1).

  In step S8, it is determined whether or not “i <n” is satisfied. If the condition is true, the process proceeds to step S9. If the condition is false, the process returns to step S7.

  In step S9, a correction profile “RefPc_i (x, v)” (c = r, g, b, i = 1 to n) is calculated by the following equation.

When 1 ≦ i ≦ n−1 RefPc_i (x, v) = Yc_i (x) IV (v)
When i = n RefPc_i (x, v) = Yc (x) IV (v)
Note that the remaining Yc (x) obtained by subtracting Yc_i of i = 1 to n−1 from PT_min is assigned to the nth projector.

  In step S10, it is determined whether or not correction profiles have been calculated for all colors (three colors in this example), and the above calculation process is completed at the end, but if not completed, the process returns to step S6 to return to another color. The above calculation process is repeated after designating.

  In this example, three primary colors have been described, but it is of course possible to apply to multiple primary colors.

  FIG. 18 shows an example of the configuration of the correction profile generator 1b.

  In this example, two image projection apparatuses 1_1 and 1_2 are assumed, and their illumination profiles “Pc_1” (c = r, g, b) and “Pc_2” (c = r, g, b) are added to the adder 55c. (C = r, g, b) are respectively sent to the luminance distribution analysis unit 39. That is, Pc_1 and Pc_2 are added by the adding unit 55c (c = r, g, b), and Pc_sum (c = r, g, b) is supplied to the luminance distribution analyzing unit 39.

  When PT_min is determined in the luminance distribution analysis unit 39, luminance conversion profiles “Yc_1” (c = r, g, b), “Yc_2” (c = r, g, b) are calculated according to the above-described procedure. These are multiplied by IV (v) from the ideal modulation characteristic function generator 40 in a multiplier 56c (c = r, g, b).

  Thus, as shown in “RefPc_1” (c = r, g, b) and “RefPc_2” (c = r, g, b), the correction profiles relating to the respective devices are generated, and these are generated by the image projecting device 1_1, 1_2 and used as the respective reference profile.

  FIG. 19 is for explaining the main part (correction value calculation unit) of the correction processing means in each apparatus, and the figure illustrates the case of the image projection apparatus 1_1. In the drawing, the apparatus identification index “_1” is omitted in the apparatus 1_1.

  The measurement result for each color is sent as “Pc (x)” (c = r, g, b) to the multiplier 53c (c = r, g, b).

  In the storage unit 54c (c = r, g, b), data “ISc (v, x)” (c = r, g, b) corresponding to each color is stored in the storage unit 54c (c = r, g, b). And the data is supplied to the multipliers 53c (c = r, g, b), respectively.

  The output data of the multiplier 53c (c = r, g, b) and the data of the profile “RefPc_1” (c = r, g, b) are stored in the correction table generator 42c (c = r, g, b). Here, RefPc_1 is set as a target modulation characteristic, and it corresponds to each color of illumination light and each pixel position based on the actual modulation characteristic “IYc (v, x)” (c = r, g, b). To correct the drive signal. Each correction data obtained in this way is written in the storage area of the data table storage unit 43c (c = r, g, b).

  FIG. 20 is an explanatory diagram relating to the correction table. The upper left (A) diagram shows the RefPc_i (for example, RefPc_1), which is a target modulation characteristic function depending on v and x. The horizontal drive voltage axis is leftward, and the vertical axis indicates luminance. The upper right (B) diagram shows the modulation characteristics obtained by intensity distribution measurement, with the horizontal drive voltage axis pointing to the right and the vertical axis representing the intensity of the modulated light. As a representative example, the figure shows the characteristic IYc (v, x) at each pixel position for the Mth pixel and the Nth pixel.

  The target modulation characteristic IT (v) is “RefPc_1 (x, v) = Yc_1 (x) × IV (v)” in the device 1_1, and the horizontal axis of FIG. (A) represents the drive voltage value before correction. For example, the luminance “Y” is determined with respect to the value indicated by “Vin” in the drawing.

  (B) In the figure, the horizontal axis represents the corrected drive voltage value, and “Vout_m” and “Vout_n” in the figure represent the drive voltage value with the luminance “Y” as the target luminance, the Mth pixel. The Nth pixel is shown.

  In FIG. 8C, the horizontal axis represents the driving voltage axis before correction, and the vertical axis represents the corrected driving voltage axis. The correction table for each pixel position is illustrated as an example of the relationship between the two. Represents.

  Before correction, Vout_m is calculated for the Mth pixel and Vout_n is calculated for the Nth pixel.

  In this manner, a correction table is created in each image projection apparatus for the modulation characteristics for each pixel related to the one-dimensional light modulation element. The drive voltage correction is performed at the time of image projection (stacking) using the correction table. However, not only the data table reference method but also a mode using correction data estimated by interpolation calculation or the like is possible. It is.

  Although the above-described correction sufficiently guarantees the uniformity of the intensity distribution in the pixel array direction, that is, the long axis direction of the one-dimensional light modulation element, the same applies to the horizontal direction (horizontal direction) corresponding to the optical scanning direction. Correction can be performed. For example, for data measured using the measurement device 28 and converted into luminance, this is considered when position dependency on an axis extending in the direction of optical scanning (hereinafter referred to as “y-axis”) is taken into consideration. “IYc (v, x, y)” (c = r, g, b). Similarly, the target modulation characteristic function is also a function including a y coordinate value, and a correction table is generated or interpolated. It is possible to calculate correction data by calculation or the like (the element drive signal may be corrected by comparing the IYc value with the target value so that the horizontal intensity distribution is constant). Note that the correction in the horizontal direction of the screen is effective for suppressing a decrease in the amount of peripheral light in a configuration in which a two-dimensional intermediate image formed by optical scanning of a one-dimensional image is projected, for example.

  According to the configuration described above, for example, the following advantages can be obtained.

  The image quality can be improved by measuring the color unevenness of the image projected on the screen and correcting the driving of the light modulation element based on the measurement data.

  -In stacking in which projection images from a plurality of projector devices are superimposed and displayed on the screen, the luminance distribution can be made uniform, and the luminous flux utilization rate does not decrease.

  -In stacking, it is not necessary to make the brightness uniform for each projector device, and there may be uneven brightness in each device (that is, there is no color unevenness or brightness unevenness in the entire image, and the uniformity of illumination It is only necessary to realize high image projection.)

It is a figure which shows the structural example of the image projection system which concerns on this invention. It is explanatory drawing of intensity nonuniformity correction which concerns on this invention. It is a figure which shows the structural example of the image projection apparatus which concerns on this invention. It is a figure which shows the principal part about the structural example of the optical system which concerns on an image projection apparatus. It is explanatory drawing regarding the operation principle of a GLV element, and the variation in a ribbon position. It is a figure for demonstrating the drive voltage change of a test signal, and an optical sensor output. It is a figure which shows the illumination profile for every color roughly. It is explanatory drawing of luminance distribution and its minimum value IY0. It is the graph which illustrated ideal modulation characteristic IT (v). It is explanatory drawing of the correction process on the basis of a target modulation characteristic. It is explanatory drawing of the correction table produced | generated for every pixel. FIG. 13 shows an example of the configuration related to the correction process, and FIG. It is a figure which shows the principal part of a correction | amendment calculation structure. It is a figure which shows the example of an apparatus used for the measurement of the modulation characteristic of a GLV element. It is explanatory drawing of the example which determines the maximum white value which can be implement | achieved about each area | region of luminance distribution. It is the figure which showed the structural example of the correction value calculating part. It is the flowchart figure which illustrated the flow of correction profile generation. It is the figure which showed the structural example of the correction profile production | generation part. It is the figure which showed the structural example about the correction value calculation. It is explanatory drawing regarding the production | generation of a correction table. It is explanatory drawing about the conventional problem.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1_1, 1_2 ... Image projection apparatus, 1a ... Profile measurement part, 1b ... Correction profile production | generation part, 4R, 4G, 4B ... One-dimensional light modulation element, 9 ... Projection optical system, 13 ... Driving means, 15 ... Light intensity distribution measurement Means 18 ... Optical scanning means 20 ... Correction means

Claims (7)

In an image projection system that generates a display image by superimposing projection images from a plurality of image projection devices,
Measure the illumination profile information indicating the intensity distribution of each color light source constituting the image projection device for each image projection device, and calculate the illumination profile of the combined projection light by adding the measurement information for each light source color. Then, based on the minimum value of the light intensity calculated by comparing the illumination profiles for each light source color, correction profile information for changing the illumination profile for each image projection apparatus is sent to each image projection apparatus. An image projection system characterized by that. The image projection system according to claim 1,
A profile measurement unit for calculating the illumination profile of the entire projection light for each light source color by summing up the illumination profiles for each image projection device,
A correction profile generation unit that generates correction profile information for each image projection device based on the minimum value of the light intensity in order to make the light intensity uniform in the illumination profile of the entire projection light. Image projection system. In an image projection apparatus provided with an image projection mode for generating a display image by superimposing the respective projection images in cooperation with other image projection apparatuses,
While measuring the information of the illumination profile indicating the intensity distribution of each color light source, calculate the illumination profile of the entire projection light combined as a total with the measurement information of the illumination profile of each color light source constituting the other image projection device, Based on the minimum value of the light intensity calculated by comparing the illumination profiles for each light source color, the correction profile information for changing the illumination profile for each image projection device, the other image projection as necessary. An image projection apparatus characterized by being sent to the apparatus. The image projection apparatus according to claim 3,
Profile measurement unit for calculating the illumination profile of the entire projection light for each light source color by summing the information of the illumination profile from the other image projection device,
Correction profile generation for generating correction profile information for each image projection device based on the minimum value of the light intensity in order to make the light intensity uniform in the illumination profile of the entire projection light including the projection light from the other image projection device An image projection device. In an image projection apparatus provided with an image projection mode for generating a display image by superimposing the respective projection images in cooperation with other image projection apparatuses,
While measuring the information of the illumination profile indicating the intensity distribution of each color light source and sending the measurement information to the other image projection device,
In order to make the light intensity uniform in the illumination profile of the entire projection light that generates the display image, the illumination profile of each color light source is changed according to the correction profile information sent from the other image projection device. An image projection device. The image projection apparatus according to claim 5,
A one-dimensional light modulation element and its driving means;
Optical scanning means for scanning a one-dimensional image obtained by modulating light using the one-dimensional light modulation element;
A projection optical system including a projection lens;
Intensity distribution in the pixel array direction corresponding to the major axis direction of the one-dimensional light modulation element upon receiving light emitted from the projection optical system when displaying an image for measuring light intensity by controlling the driving means Light intensity distribution measuring means for measuring
In the image projection mode, correcting means for correcting the driving signal related to the one-dimensional light modulation element based on the correction profile information and controlling the driving means to make the light intensity uniform in the pixel array direction. An image projection apparatus characterized by comprising: The image projection apparatus according to claim 6,
In the image projection mode when used alone, the correction means controls the drive means by correcting the drive signal related to the one-dimensional light modulation element based on the measurement data from the light intensity distribution measurement means. By doing so, the light intensity in the pixel arrangement direction is made uniform.

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