JP2006072221A - Image generating apparatus and image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently reduce uneven luminance, uneven color or the like of a picture in a scanning direction in an image generating apparatus furnished with an optical scanning means, and to prevent an resulting efficiency reduction and cost raise. <P>SOLUTION: In the image generating apparatus 1, the forming position of a one-dimensional image obtained by optical modulation using a one-dimensional optical modulation element 3a varies along a predetermined scanning direction according to the action of the optical scanning means 5. A control means 7 controls a scanning speed for compensating luminance variation in the scanning direction on the basis of the luminance distribution characteristic in the scanning direction. The luminance is reduced as the scanning speed at a scanning position is increased, and the luminance is increased as the scanning speed is reduced. Hence, the scanning speed is increased at the center in the scanning direction and decreased at side areas in the scanning direction to compensate the variation in the luminance distribution due to an optical factor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for reducing luminance unevenness, color unevenness, and the like in an optical scanning direction in application to an apparatus that performs image generation and image display using an optical scanning unit such as a galvanometer scanner.

  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 (hereinafter referred to as “Grating Light Valve”) developed by Silicon Light Machine (SLM), USA. GLV ") is formed of a reflective diffraction grating, and a plurality of movable ribbons are arranged at predetermined intervals, 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. For example, a one-dimensional image is formed by laser light modulated using a GLV element, and optical scanning for forming a two-dimensional image by scanning the one-dimensional image along a predetermined direction (for example, a horizontal direction). In the configuration having the means, a two-dimensional image can be displayed by projecting an image on a screen using a projection lens.

  Further, in a multi-projection system using a plurality of projector devices, a format (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 a plurality of projector devices There is a form in which the projected images are displayed so as to be superimposed on the same place (so-called stacking).

  By the way, it is difficult to create a device that is optically free from luminance unevenness, and there are problems such as an increase in cost required for improving characteristics and performance, or a decrease in light utilization efficiency. .

  For example, in a tiling system that uses a plurality of projector devices that have brightness unevenness or color unevenness in the optical scanning direction, brightness unevenness due to the occurrence of dark portions or the like at the joints of patch images by each device may be noticeable. Is a problem. In other words, it is necessary to calibrate the brightness unevenness or the like for each projector device in order to prevent degradation in image quality or the like when displaying a composite image.

  In addition, it is necessary to take measures against uneven brightness in the optical scanning direction due to optical factors (for example, angle dependency of lenses, mirrors, etc.) and uneven speed of the scanner.

  Therefore, the present invention sufficiently reduces luminance unevenness and color unevenness in the optical scanning direction in the image generation apparatus and image projection apparatus provided with the optical scanning means, and therefore does not involve a decrease in efficiency or a significant increase in cost. The challenge is to do so.

  In order to solve the above-described problems, the present invention provides a luminance in the scanning direction in a configuration in which the formation position of a one-dimensional image obtained by light modulation using a one-dimensional light modulation element is changed along a predetermined scanning direction. Control means for controlling the scanning speed is provided to cancel the luminance change in the scanning direction based on the distribution characteristics.

  Therefore, in the present invention, when the luminance distribution in the scanning direction is not constant, the scanning speed is changed in accordance with the distribution tendency (the luminance decreases when the scanning speed at the scanning position is increased, and the luminance decreases when the scanning speed is decreased). Therefore, luminance unevenness in the scanning direction can be corrected.

  According to the present invention, luminance unevenness and color unevenness in the scanning direction can be reduced by scanning speed modulation control. Moreover, it is not necessary to limit the luminance value by image signal processing, and only the scanning speed is controlled, which is advantageous in terms of efficiency and cost. In addition, when applied to a system in which a plurality of projected images are arranged vertically or horizontally on a screen or superimposed, it is possible to prevent luminance unevenness, color unevenness, etc. from occurring as a whole display image (for example, joints between adjacent patch images). Is inconspicuous).

  Then, scanning control is performed so that the scanning speed is slower in the peripheral area than in the center of the scanning range, and control is performed such that the scanning speed is relatively dark in the center of the scanning range and relatively bright in the peripheral area, An effect of canceling the luminance distribution tendency based on optical factors can be obtained.

  Further, in the configuration having the correction unit that corrects the image distortion by changing the modulation timing related to the one-dimensional light modulation element according to the scanning speed, it is possible to prevent the image quality from being deteriorated due to the change in the scanning speed. That is, if the light modulation is performed at a constant time interval with respect to the change in the scanning speed, the interval between the display lines changes according to the change in the scanning speed. The modulation timing is controlled so that the time interval of the modulation operation according to (2) is shortened (preferably, the product of the scanning speed and the time interval of the modulation operation is controlled to be constant).

  In order to eliminate luminance unevenness that cannot be removed by scanning speed control alone, the peak luminance during light modulation is further corrected by correcting the drive signal of the one-dimensional light modulation element based on the luminance distribution characteristics in the scanning direction. Is preferably adjusted.

  High performance by reducing unevenness of brightness and color in the scanning direction when applied to optical projection means equipped with optical scanning means and projection optical system for one-dimensional images obtained by light modulation using a one-dimensional light modulation element And improvement of image quality can be realized.

  FIG. 1 is a schematic diagram showing a basic configuration example of an image generation apparatus according to the present invention.

  In the image generation apparatus 1, the light from the light source unit 2 is modulated using the light modulation unit 3, and the modulated light is sent to the optical scanning unit 5 through the optical system 4 and scanned in a predetermined direction. . Then, a two-dimensional image “gg” is formed via the optical system 6.

  The light source unit 2 includes, for example, a laser light source using a semiconductor laser, a solid-state laser, and the like, and an illumination optical system for forming a linear beam, and includes a one-dimensional light modulation element 3 a constituting the light modulation unit 3. On the other hand, light having a uniform intensity distribution (so-called “top hat” shape) is irradiated.

  A video signal is input to the driving means 3b of the one-dimensional light modulation element 3a, and a drive signal corresponding to the video signal is generated and supplied to the one-dimensional light modulation element 3a.

  The optical system 4 includes a spatial filter such as a schlieren filter, a diffuser (diffuser), and the like. In a configuration in which optical scanning is performed after projection, a projection optical system using a projection lens or the like is included.

  As the optical scanning means 5, a galvanometer scanner or the like is used, and includes a rotary mirror 5a and a drive source 5b.

  In the configuration in which projection is performed after optical scanning, the optical system 6 includes a projection optical system using a projection lens. However, in the configuration in which optical scanning is performed after projection, the optical system 6 is unnecessary. In the configuration having the optical system for measuring the light intensity distribution, the optical system is included in the optical system 6 or the optical system 4.

  The light emitted from the laser light source or the like is modulated using the one-dimensional light modulation element 3a, and the formation position of the one-dimensional image obtained thereby is controlled in a predetermined direction (one-dimensional image A two-dimensional image “gg” is generated by scanning along a scanning direction orthogonal to the forming direction.

  The control system related to the optical scanning unit 5 is configured by using a control unit 7, a drive unit 8, a drive source 5 b, and a detection unit 9.

  The control means (scanning control means) 7 is for controlling the operation speed of the optical scanning means 5 in order to cancel the luminance change in the scanning direction based on the luminance distribution characteristic (design value or measurement value) in the scanning direction. Is provided. Then, the drive source 5b is controlled according to the control signal sent from the control means 7 to the drive means 8, and the detection information of the position and speed of the drive source 5b is fed back from the detection means 9 to the control means 7.

  2A and 2B are explanatory diagrams for correction of the luminance distribution according to the present invention, in which FIG. 2A shows a distribution example based on optical factors, and FIG. 2B shows a distribution example based on a change in optical scanning speed. , (C) shows an example of a distribution after correction in consideration of (A) and (B). In each figure, the horizontal axis indicates the position in the scanning direction (for example, the horizontal direction), and the vertical axis indicates the luminance (light intensity).

  First, FIG. (A) schematically shows a distribution tendency when the optical characteristics of the projection lens or the like are integrated, and the intensity at the center in the scanning direction is relative as shown in the graph curve “ga”. The strength tends to be high, and the strength tends to be low at the periphery.

  FIG. 5B schematically shows a distribution tendency when the operation speed (scanning speed) of the optical scanning unit 5 is changed. As shown by the graph curve “gb”, the intensity at the center in the scanning direction is shown. Is relatively low and the strength is high in the periphery. That is, the distribution tendency opposite to FIG.

  Therefore, by combining the (A) diagram and the (B) diagram, ideally a flat characteristic as shown by the graph line “gc” in the (C) diagram, that is, a uniform distribution along the scanning direction can be obtained. Is possible.

  If the operation speed of the optical scanning means 5 is controlled to be constant within a predetermined range in the scanning direction, the distribution tendency in FIG. (A) is reflected as it is in the distribution after scanning, so that the operation speed of the optical scanning means is modulated. Then, the drive control is performed so that the operation speed of the optical scanning unit 5 is slower in the peripheral region than in the center of the scanning range. That is, if the operation speed of the optical scanning unit 5 is relatively slow (or fast), the intensity can be increased (or decreased). Therefore, the operation speed is increased in order to decrease the intensity in the central portion of the scanning range. In order to increase the intensity in the peripheral area of the scanning range, the operation speed may be decreased. This makes it possible to cancel the distribution tendency of FIG.

  In the image generation, when the operation speed of the optical scanning unit 5 is changed, the modulation timing by the one-dimensional light modulation element cannot be performed at a constant time interval, so the modulation timing is changed according to the scanning position. It is necessary to make it.

  FIG. 3 is a diagram for explaining the relationship between velocity modulation and image distortion in optical scanning. FIG. 3A shows scanning characteristics, the horizontal axis represents the y-axis indicating the scanning direction, and the vertical axis represents the vertical axis. Indicates the scanning speed “v”. FIG. 5B shows image distortion that occurs when the modulation timing is performed at a constant time interval, and FIG. 4C shows how image distortion is removed by correction. The “x” axis is an axis orthogonal to the y axis and extending in a direction parallel to the long axis of the one-dimensional light modulation element. For example, when the y axis is taken in the horizontal direction, the x axis is in the vertical direction. Is the axis.

  As shown in FIG. 6A, the speed v changes so as to increase at the center of the scanning range on the y-axis and decrease at the peripheral area with the constant speed “Vc” as a reference. That is, by controlling the scanning speed so that it is dark in the center of the scanning range and bright in the peripheral area, it is possible to cancel the change in the luminance distribution due to the optical factors described above.

  By the way, when the modulation related to the one-dimensional light modulation element is performed at a constant time interval, the interval between the display lines (vertical lines in the figure) changes according to the change in the scanning speed v as shown in FIG. (The pixel pitch in the y-axis direction changes.) That is, the peripheral line interval “Δya” in the y-axis direction is relatively narrow, the central line interval “Δyb” in the y-axis direction is relatively wide, and is not constant on the y-axis (the image is distorted). Occurs.)

  Therefore, when the scanning speed v is high (or low), if the modulation timing is controlled so that the time interval of the modulation operation related to the one-dimensional light modulation element is short (or long), FIG. Thus, the line interval “Δy” in the y-axis direction can be made constant.

  The correction means 10 shown in FIG. 1 sends a control signal to the driving means 3b, and image distortion occurs by changing the modulation timing of the one-dimensional light modulation element 3a according to the operating speed of the light scanning means 5. It corrects so that there is no. In other words, since the scanning speed v is a function “v (y)” of the scanning position (y value), if the speed distribution v (y) is grasped in advance or by measurement from the information on the scanning position, it corresponds to the speed v. Thus, the modulation timing of the one-dimensional light modulation element 3a can be controlled to prevent image distortion (the modulation time interval is changed according to the scanning speed characteristic). Alternatively, in the embodiment in which the modulation timing of the one-dimensional light modulation element 3a is controlled based on the measurement result of the scanning position for each time, the scanning position at a certain time is measured, and the image distortion is based on the scanning position at each timing. Can be corrected (in principle, it is the same as the concept of speed).

  Next, a configuration example of the image projection apparatus will be described.

  FIG. 4 shows an outline of the configuration, and an apparatus for displaying an image by modulating laser light using a one-dimensional light modulation element will be described below.

  In the optical system of the image projection apparatus 11, the light emitted from the light source 12 reaches the light modulation unit 14 via the illumination optical system 13, and the light modulated here passes through the color synthesis unit 15 and the spatial filter 16 and is optically scanned. The unit 17 is reached.

  As the light source 12, for example, laser light sources 12R, 12G, and 12B 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 13 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 13R, 13G, and 13B corresponding to the respective colors of R, G, and B are used.

  The light modulation unit 14 is configured by using one-dimensional light modulation elements 14R, 14G, and 14B corresponding to the respective colors of R, G, and B, and a profile (so-called “so-called”) that is substantially uniformized through the optical systems 13R, 13G, and 13B. 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 (23) described later, and the position of the first surface is controlled in a direction along the irradiation direction of the laser beam. That is, when the drive voltage is applied according to the image signal, the movable ribbon moves with a displacement amount corresponding to the voltage, and in this state (so-called pixel-on time), a reflective diffraction grating for incident light is formed (the first-order diffracted light Occurrence). 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 modulated color light is synthesized by the color synthesis unit 15 and then sent to the spatial filter 16.

  The spatial filter 16 has a role of selecting a diffracted light component of a specific order. In this example, a schlieren filter is used to extract ± first-order diffracted light from light modulated by 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 17 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”.

  As the scanning method, the following method can be cited (FIG. 5 shows a waveform example of the scanner drive signal “Sθ”).

(A) Unidirectional drawing method (see FIG. 5A)
(B) Bidirectional drawing method (see FIG. 5B)

  In the method (A), as shown in FIG. 5A, a sawtooth drive signal is used. In the figure, “Ta” is a period immediately after the start of scanning, “Tb” is a drawing period, and “Tc” is Each period (return line period) for returning to the scanning start position after drawing is shown. For example, when the left edge of the display screen is set as the scanning start position and the right edge is set as the scanning end position, the vertical line extending from the left edge to the first direction is 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 method (B), as shown in FIG. 5B, a triangular-wave drive signal is used. In the figure, “T1” is a period immediately after the start of scanning, and “T2” is a first drawing period ( “Outward path”, “T3” indicates a period for reversing the scanning direction after drawing, “T4” indicates a second drawing period (return path), and “T5” indicates a period for returning to the scanning start position after drawing, respectively. Yes. For example, when the left edge and the right edge of the display screen are set as the scanning start position and the scanning end position, optical scanning starts from the left edge, and the vertical line extending in the first direction extends in the second direction. After scanning along, 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 18 (see FIG. 4), and then is projected onto the screen “SCN” by the projection optical system 19 to display an image.

  The light diffusing unit 18 is provided to obtain diffused light using a diffuser for speckle noise reduction or the like, and the projection optical system 19 is a two-dimensional projection optical system including a projection lens.

  A light detection device 20 is provided for the projection optical system 19, and receives light emitted from the projection optical system 19 to detect the light intensity.

  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 modulation timing correction unit 22 through the signal processing unit 21.

  In the signal processing unit 21, 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 modulation timing correction unit 22 corrects the modulation timing of the one-dimensional light modulation elements 14R, 14G, and 14B with reference to information from a correction data calculation unit (26) described later.

  The drive means 23 is provided to drive the one-dimensional light modulation elements 14R, 14G, and 14B, includes an element drive circuit, and sends a drive signal to each of the light modulation sections 14 according to a command from the modulation timing correction section 22. Each one-dimensional light modulator is supplied (the laser light of each color is modulated by driving control of the light modulator). Note that “TEST” shown in the figure indicates a test signal for displaying a measurement image used when measuring the light intensity distribution.

  The light intensity distribution measurement processing unit 24 is provided to process the detection information from the light detection device 20 and measure the light intensity distribution in the major axis direction and the light scanning direction of the one-dimensional light modulation element. A light intensity distribution measuring means 25 is configured together with the light detection device 20. That is, when the “TEST” signal is used, the intensity distribution is measured by receiving the light emitted from the projection optical system 19, and the measurement result is sent to the optical scanning control unit 27 and the correction data calculation unit 26.

  The optical scanning control unit 27 (corresponding to the control unit 7) constitutes an optical scanning unit 28 together with the optical scanning unit 17, and is obtained by modulating light using a one-dimensional light modulation element. Perform image scanning control. At that time, based on the measurement data (intensity distribution characteristic data) from the light intensity distribution measurement processing unit 24, the intensity change in the scanning direction is canceled, and the scanning speed is controlled to make the intensity distribution in the direction uniform. The optical scanning control unit 27 sends a control signal to the optical scanning unit 17 in accordance with a synchronization signal (not shown) and a signal from the light intensity distribution measurement processing unit 24, and controls its operation (rotation of the galvanometer mirror). The optical scanning unit 17 is provided with an angle sensor or the like for detecting the scanning position, and the detection information of the scanning position is sent to the optical scanning control unit 27. Further, based on a control signal sent from the optical scanning control unit 27 to the optical scanning unit 17, control of the rotational phase (scanning position) of the galvanometer mirror or the like and modulation control related to the scanning speed are performed. Then, the scanning position information is notified from the optical scanning control unit 27 to the modulation timing correction unit 22.

  In this example, the correction data calculation unit 26 constitutes a correction unit 30 (or optical modulation timing control unit) together with the storage unit 29 and the modulation timing correction unit 22, for example, a CPU (Central Processing Unit), a memory, or the like. It is realized using hardware and a processing program. That is, the correction unit 30 performs correction processing related to image distortion by changing the modulation timing related to the one-dimensional light modulation element according to the scanning speed.

  When displaying a light intensity measurement image and performing measurement by the light intensity distribution measuring means 25, for example, as a preparatory stage before image projection, the measurement image is output from the projection optical system 19 when performing calibration or the like. And the form detected with the photon detection apparatus 20 is mentioned. Alternatively, a mode in which an image for measurement is output from the projection optical system 19 and detected by the light detection device 20 so as not to adversely affect the image display while performing image projection is also possible.

  FIG. 6 is a schematic view illustrating the main part of the optical system according to the image projection apparatus 11.

  The one-dimensional light modulation elements 14R, 14G, and 14B corresponding to the R, G, and B colors are respectively irradiated with linear beams from an illumination optical system (not shown).

  Each modulated laser beam is optically synthesized using the color synthesis mirrors 31 and 32, and then reaches the galvano scanner 36 via the Offner relay system 33 and undergoes optical scanning.

  The Offner relay system 33 is configured by using a primary mirror (concave mirror) 34 and a secondary mirror (convex mirror) 35. The light after color synthesis is first reflected by the primary mirror 34 and then the secondary mirror. After being reflected at 35 and further reflected at the main mirror 34 for the second time, it is emitted toward the galvano scanner 36. By giving the secondary mirror 35 the function of a schlieren filter (the function of separating the specularly reflected light component and the diffracted light component and taking out only the diffracted light of a specific order) or attaching the schlieren filter to the secondary mirror 35 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 36 from the Offner relay system 33 is a direction perpendicular to the paper surface of FIG. 6, and a two-dimensional intermediate image “g2” is formed by optical scanning. In this example, in order to remove the field curvature of the two-dimensional image, a field curvature correcting optical system 37 is disposed after the galvano scanner 36.

  The two-dimensional intermediate image g2 after the field curvature correction is enlarged and projected on the screen by the projection optical system 19, and a measuring device 38 is used to measure the light intensity distribution. This measuring device 38 constitutes the light detecting device 20 of the light intensity distribution measuring means 25 described above, and is located in the vicinity of the exit of the projection optical system 19, and after condensing the emitted light from the projection optical system 19. Detect the averaged light intensity.

  In this example, the light collecting element 39, the integrating sphere 40, and the light detecting means 41 are provided, and the light emitted from the projection optical system 19 is condensed by the light collecting element 39 and introduced into the integrating sphere 40, and the integrating sphere The light detection means 41 detects the light intensity averaged by 40.

  The condensing element 39 using a Fresnel lens or the like has a function of condensing all the light emitted from the projection lens and re-imaging it.

  The laser beam condensed by the condensing element 39 is introduced from an opening (not shown) formed in the integrating sphere 40, and the light intensity in the integrating sphere 40 is made uniform by multiple reflection inside. . That is, the integrating sphere 40 constitutes averaging means, and the averaged light intensity is detected by the light detection means 41.

  The light sensor constituting the light detection means 41 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 24). It is processed.).

  As an installation form of the measuring apparatus 38, for example, in a configuration form in which the measuring apparatus can be attached to the main body of the image projection apparatus, the measuring apparatus is used in the main body only when measuring 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 38 to a position near the projection optical system 19 at the time of measuring the light intensity distribution. 19 outgoing lights can be introduced into the integrating sphere 40 in the measuring device 38. Note that it is necessary to move the measuring device 38 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 first pixel starts from the first pixel. Then, the measurement data is collected by sequentially performing the process of recording the output of the optical sensor by turning on each pixel individually (pixel-on state) up to the 1080th pixel. Thereby, independent light intensity measurement is possible for each pixel. In order to collect two-dimensional measurement data including the scanning 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 36 (for example, a measuring device). The position of the integrating sphere 40 and the optical sensor is controlled by moving the movable stage or the like provided on the surface). However, to reduce the processing burden caused by measuring at all positions in the scanning direction, measure only a few display lines in the scanning direction and use the result to calculate the intensity distribution. A method of estimating is preferable.

  Instead of using the measured value of the light intensity distribution, it is possible to use the distribution characteristics that are known from the design value and simulation results. Processing based on data is desirable. In other words, when taking into account changes over time, etc., it is necessary to measure the light intensity distribution periodically or as necessary, and to correct the unevenness in intensity in the scanning direction based on the measurement data of the light intensity distribution. Scan speed characteristics can be calculated before or during image projection as a function of scan position.

  FIG. 7 shows an example 42 of a circuit configuration for driving a one-dimensional light modulation element (GLV element) based on a video signal. In the figure, only one of the three primary colors is representatively shown, but other colors have the same configuration.

  The video signal is first input to the image input circuit 43, subjected to RGB signal conversion, inverse γ correction, and the like, and then sent to the XY conversion circuit 44.

  The XY conversion circuit 44 performs vertical / horizontal conversion on the image data for one screen, and changes the arrangement order of the data. That is, to generate a two-dimensional image by scanning a one-dimensional vertical line (image line) along the scanning direction (horizontal direction), it is necessary to divide one screen as a set of vertical lines. On the other hand, in the input image data, since the horizontal lines in which the pixels are arranged in time series are arranged in the vertical direction, it is necessary to convert the format of the image data.

  The image data for one screen after XY conversion is stored in the frame memory 45 in units of vertical lines. In the method (A), data for each vertical line may be stored in the frame memory 45 in chronological order, but in the case of the method (B), the scanning direction is reversed for each screen. Care must be taken (the order in which the vertical lines are stored in the frame memory 45 is opposite between the forward drawing period and the backward drawing period).

  The image output circuit 46 sends the image data “Data” stored in the frame memory 45 under the control of the control circuit 47 to the signal conversion circuit 48 line by line, and outputs a data enable signal “DE” to the circuit. And the clock signal “CLK” and the like are output.

  The frame memory 45 and the image output circuit 46 are controlled by a signal from the control circuit 47, and a signal “RQT” from a control circuit 49 to be described later is sent to the control circuit 47 and modulated based on the signal. And projection timing control is performed. Further, a frame synchronization signal “FRMsync” is sent from the image output circuit 46 to a control circuit 49 described later.

  The signal conversion circuit 48 receives an image for one line (vertical line image) from the image output circuit 46, generates a drive signal “1Dim-Data” for the one-dimensional light modulation element according to the image data, and stores the memory 51 To output and store. In addition, the signal conversion circuit 48 instructs the control circuit 52 in the subsequent stage to output the signal “TSS” for instructing transfer of the drive signal “1Dim-Data” and the drive signal to the one-dimensional light modulation element. The signal “DIS” is output. That is, the drive signal read from the memory 51 according to TSS is supplied to the one-dimensional light modulation element via the amplifier 53 according to the timing defined by DIS.

  The control circuit 49 receives the frame synchronization signal “FRMsync”, adjusts the operation timing of the signal conversion circuit 48, generates the signal RQT based on the data stored in the memory 50, and sends it to the control circuit 47. The memory 50 stores data for defining the modulation timing of the one-dimensional light modulation element (data for determining the generation timing and phase of the RQT), and the data includes design values or speed characteristics related to the scanning characteristics. Calculated based on measured values. Then, the data is read out to the control circuit 49 and used to generate RQT.

  FIG. 8 shows the relationship between the frame synchronization signal “FRMsync” and the modulation timing control signal RQT.

  In this example, the method (B) is adopted, and the drawing period in the forward period indicated by “T1” in the drawing includes an RQT signal for one screen, and within the return period indicated by “T2” in the drawing. The RQT signal for the next one screen is included in the drawing period. “ΔT” indicates the pulse interval of the RQT, which differs depending on the scanning position in one screen, and differs between the forward path and the backward path (this is the mechanism, circuit characteristics, etc. constituting the optical scanning system). This is caused by the asymmetry between the forward path and the return path, and it is necessary to match the formation positions of the vertical line images between the forward path and the return path so as not to shift. Further, it is necessary to adjust the phase so that the image forming position is not affected due to the phase shift between the detection information (angle sensor information and the like) related to the scanning position and the actual scanning position.

  FIG. 9 is a timing chart illustrating a state in which the modulation (see “MOD”) of the one-dimensional light modulation element is performed starting from the rising edge of the pulse of the signal RQT.

  Upon receiving the signal RQT, the control circuit 47 outputs the data “D1” for one line in the frame memory 45 within the period indicated by DE (Data Enable) as shown in the “Data” column, and the image output circuit 46 to the signal conversion circuit 48.

  Transfer of data “1Dim-Data” is started by the signal TSS sent from the signal conversion circuit 48 to the control circuit 52, and a drive signal is supplied to the one-dimensional light modulation element (GLV element) according to the signal DIS to perform light modulation operation. ("Td" in the "MOD" column indicates the delay time from RQT to the start of modulation).

  FIG. 10 is a schematic diagram showing the relationship between the scanning speed and the pulse interval of the RQT, where the y-axis direction indicates the scanning direction, and the x-axis direction orthogonal to this corresponds to the long-axis direction of the one-dimensional light modulation element. The arrangement direction is shown.

  In the peripheral part in the scanning direction, the scanning speed is slow and the pulse interval ΔT is relatively long. In addition, the scanning speed is high at the center in the scanning direction, and the pulse interval ΔT is relatively short. Such time interval control is calculated based on scanning speed detection information that is a function of the y position (specifically, speed information obtained by differentiating the detection value of the deflection angle θ of the galvanometer mirror with respect to time). The signal RQT follows the data stored in the memory 50. In actual scanning control, for an angle signal that determines RQT (a signal obtained by correcting the phase lag with respect to the detection signal of the scanning angle), data for one screen with respect to the frame synchronization signal FRMsync is created as a reference table, and the phase Projection timing control for FRMsync is performed according to the relationship between information and angle information (for example, angle information at a predetermined time can be arbitrarily defined by data shift, interpolation, correction, or the like). The advantage of this method is that it is easy to control and efficient in terms of the system. (It is important to construct all the controls with reference to the frame sync signal as a reference, and the system can be handled simply. The video signal is also based on the frame sync signal, which makes sense in terms of system consistency.)

  FIG. 11 shows the relationship between the scanning speed “v” on the horizontal axis and the pulse interval “ΔT” on the vertical axis.

  When ΔT0 with respect to speed v0 is used as a reference, ΔTh is smaller than ΔT0 for Vh larger than v0, and ΔTl is larger than ΔT0 for vl smaller than v0. That is, if the modulation timing is controlled so that the product of ΔT and v is constant, the formation pitch (one-dimensional image interval) of the constituent lines (vertical lines) of one screen is made constant so that image distortion does not occur. Can be prevented.

  ΔT is a function ΔT (v) of the scanning speed v (y) and a function of the scanning position y.

  The procedure of scanning control in the image projection apparatus 11 is summarized as follows.

(1) Prior measurement of brightness distribution characteristics and storage of measurement data (2) Calculation and storage of scanning speed modulation control data in scanning direction (3) Calculation of modulation timing control data of one-dimensional light modulation element in scanning direction (4) Start of scanning and light modulation (5) Control of scanning speed according to scanning position and modulation timing control of one-dimensional light modulation element according to scanning speed

  In (1), the intensity distribution is measured while the scanning speed is substantially constant in the drawing range. In (5), when the light intensity at the scanning position is high (or low), the scanning speed is increased (or decreased), and when the scanning speed is large (or small), the one-dimensional light modulation element is used. Shorten (or lengthen) the time interval of the modulation operation.

  As a countermeasure against intensity unevenness that cannot be removed only by modulation control of the scanning speed according to the scanning position, intensity unevenness of the projected light is adjusted by adjusting the peak luminance when performing light modulation using a one-dimensional light modulation element. Can be removed.

  12A and 12B are explanatory diagrams of luminance unevenness correction. FIG. 12A shows a distribution example obtained by optical factors and scanning speed factors. FIG. 12B shows a distribution example related to peak luminance adjustment. The figure shows an example of the distribution after correction.

  (A) As exaggeratedly shown in the figure, when there is no luminance correction, peak portions are recognized at the left and right peripheral portions in the scanning direction, and the central portion in the scanning direction is substantially flat. This is because, in the relative relationship between the optical factor and the scanning speed factor, the scanning speed is slower than necessary at the periphery in the scanning direction.

  FIG. 4B shows an example of distribution when the peak luminance is adjusted to cancel the distribution of FIG. 1A, and each graph curve is parallel to the horizontal axis with respect to the graph curve of FIG. The curve is obtained by reversing the vertical relationship with respect to the right axis, the luminance is the lowest in the left and right peripheral portions, and the luminance is maximum in the peripheral portion. The peak luminance adjustment is illustrated as a representative case where the graph curve indicated by the solid line is 100%, the dashed curve curve is 80%, and the alternate long and short dash line curve is 30%.

  (C) shows an example of a uniform distribution after correction. The graph line shown by a solid line is 100%, the broken line is 80%, and the alternate long and short dash line is 30%. It is illustrated as an example.

  For example, in order to prevent the luminance value in the scanning direction from exceeding the upper limit (maximum allowable value), it is necessary to adjust (reduce) the peak luminance and limit the luminance value to the upper limit (for example, 80%). In the peak adjustment, the luminance is reduced by 20%.) The luminance is determined by the minimum luminance among the three primary colors red, green, and blue. For example, the minimum luminous flux values of red light and blue light are both 4000 lm (lumens), and the minimum luminous flux value of green light is In the case of 3000 lm, the maximum white brightness that can be achieved is limited by the minimum brightness of green light.

  As a method for correcting the peak luminance, for example, a method of storing correction data in a reference table and reading it during scanning (such as a look-up table method using a memory in a processing circuit related to image data) can be used. Taking an apparatus using a GLV element as an example, output luminance information for each driving level is provided when element driving is performed by gradation control with a predetermined number of bits (for example, 10 bits). Therefore, for example, if the green luminous flux value is 3000 lm and the red luminous flux value is 4000 lm, the drive level of the GLV element corresponding to red is converted to match the output luminance of the green light. The reference table for doing this can be calculated.

  Note that correction in the direction of increasing brightness beyond the upper limit of luminance is not possible, and correction in the direction of decreasing brightness is performed (the drive voltage to the one-dimensional light modulation element is adjusted by correcting the drive signal in accordance with the image signal). However, since it is sufficient to perform correction by image signal processing, it is possible to correct luminance unevenness and obtain a high-quality image without significantly increasing the cost.

  FIG. 13 shows a configuration example for realizing the above-described luminance distribution correction.

  When the video signal VIDEO is input to the signal processing unit 21, the color signals of the three primary colors are output through an internal inverse γ correction circuit, a color space conversion circuit, and the like, and are sent to the data correction unit 54 at the subsequent stage.

  The detection information from the measuring device 38 is sent to the detection signal processing unit 55 and processed by the gain adjustment circuit 55a and the A / D conversion circuit 55b. The gain adjustment circuit 55a is provided to correct a difference in detection sensitivity of the optical sensor with respect to the detection signal of the modulated light. The A / D conversion circuit 55b converts the gain-adjusted analog signal into a digital signal, and sends the data to the measurement data storage unit 54a in the data correction unit 54 for storage. The detection signal processing unit 55 constitutes the light intensity distribution measurement processing unit 24.

  The data correction unit 54 includes a measurement data storage unit 54a, a correction value calculation unit 54b, a data table storage unit 54c, and a selection unit 54d.

  The data from the detection signal processing unit 55 includes information on luminance unevenness due to optical factors such as the projection lens and the scanning speed factor of the optical scanning unit, and the data is stored in the measurement data storage unit 54a.

  The correction value calculation unit 54b performs the calculation process necessary for adjusting the peak luminance based on the measurement data, and sends the luminance correction data obtained as a result to the data table storage unit 54c to be stored in the storage area. .

  When the data table storage unit 54c receives a drive signal before correction, the data table storage unit 54c reads out the data after luminance correction and outputs the drive signal. 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 54c is calculated as an arithmetic processing unit. Replace with.

  The selection unit 54d switches the output from the data table storage unit 54c and the test signal for measurement and sends them to the drive unit 56. That is, the test signal (TEST) is selected when measuring the luminance distribution, and the output of the data table storage unit 54c is selected when displaying the image.

  The output of the selection unit 54d is sent to a light modulation unit using a GLV element after passing through a D / A conversion circuit 56a constituting the drive unit 56 and a drive circuit 56b in the next stage. The D / A conversion circuit 56a is provided to convert the digital signal output from the data correction unit 54 into an analog signal, and the drive circuit 56b 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 57 performs timing control, signal switching, and the like by sending control signals to the respective components such as the signal processing unit 21, the data correction unit 54, the detection signal processing unit 55, and the laser light source is turned on and off. It also has functions such as optical scanning control when measuring the intensity distribution.

  In addition, with respect to the pixel arrangement direction corresponding to the major axis direction of the one-dimensional light modulation element, based on the measurement data of the light intensity distribution, by correcting the drive signal related to the one-dimensional light modulation element, intensity unevenness or color unevenness ( Irradiation light distribution non-uniformity) can be removed. That is, the correction data for the drive control related to the one-dimensional light modulation element is calculated from the data relating to the vertical line measured with respect to the unevenness of the luminance distribution, and the drive related to the one-dimensional light modulation element is used by using the correction data at the time of image projection. Signal correction control may be performed (for example, a correction table is created for the modulation characteristics of each pixel related to the one-dimensional light modulation element, and the drive voltage is corrected during image projection using the correction table. Alternatively, not only the data table reference method but also a mode using correction data estimated by interpolation calculation or the like is possible.

  The configuration described above realizes two-dimensional luminance unevenness correction including the first direction corresponding to the major axis direction of the one-dimensional light modulation element and the second direction (scanning direction) orthogonal to the direction. It becomes possible.

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

-By measuring the uneven brightness of the projected light and controlling the scanning speed based on the measurement data, it is possible to make the brightness distribution in the scanning direction uniform, improve the image quality, and provide a high-quality image.
-The modulation timing of the one-dimensional light modulation element is controlled in accordance with the scanning speed and can be corrected so as not to cause image distortion.
-By correcting the driving signal of the one-dimensional light modulation element and adjusting the peak luminance at the time of light modulation, the luminance unevenness in the scanning direction can be reduced (because it depends on signal processing, it can be corrected without a significant increase in cost). ).
In a system that uses a plurality of projector devices to connect or superimpose projected images from each device and display them on the screen, it is possible to achieve uniform luminance distribution, especially when scanning speed modulation control is performed. A reduction in luminous flux utilization can be suppressed.

It is the schematic which shows the basic structural example of the image generation apparatus which concerns on this invention. It is explanatory drawing of the brightness nonuniformity correction which concerns on this invention. It is explanatory drawing which shows the relationship between scanning speed modulation and image distortion. It is a figure which shows the structural example of the image projection apparatus which concerns on this invention. It is explanatory drawing regarding a scanning system. It is the figure which illustrated the principal part about the optical system which concerns on an image projection apparatus. It is a figure which shows the circuit structural example about the drive of the one-dimensional light modulation element based on a video signal. It is a figure for demonstrating the relationship between a frame synchronizing signal and a modulation timing control signal. It is a timing chart for demonstrating the modulation timing of a one-dimensional light modulation element. It is the schematic which shows the relationship between a scanning speed and the pulse interval of a modulation timing control signal. It is the graph which illustrated the time interval of the light modulation operation with respect to the scanning speed. It is explanatory drawing of the brightness nonuniformity correction | amendment in a scanning direction. It is a block diagram which shows the structural example which concerns on brightness | luminance unevenness correction | amendment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image generation apparatus, 3a ... One-dimensional light modulation element, 3b ... Driving means, 5 ... Optical scanning means, 7 ... Control means, 10 ... Correction means, 11 ... Image projection apparatus, 14R, 14G, 14B ... One-dimensional light Modulating element, 19 ... projection optical system, 23 ... driving means, 28 ... optical scanning means, 30 ... correcting means

Claims (10)

In an image generating apparatus configured to change a formation position of a one-dimensional image obtained by light modulation using a one-dimensional light modulation element along a predetermined scanning direction,
An image generating apparatus comprising: control means for controlling a scanning speed in order to cancel out a luminance change in the scanning direction based on the luminance distribution characteristic in the scanning direction. The image generation apparatus according to claim 1,
Scanning control is performed so that the scanning speed is slower in the peripheral area than in the center of the scanning range. The image generation apparatus according to claim 1,
An image generation apparatus comprising: a correction unit that performs correction processing related to image distortion by changing a modulation timing related to the one-dimensional light modulation element according to a scanning speed. The image generating apparatus according to claim 3,
A modulation timing is controlled so that the time interval of the modulation operation related to the one-dimensional light modulation element becomes shorter as the scanning speed is higher. The image generation apparatus according to claim 1,
In order to reduce the luminance unevenness in the scanning direction, the driving signal of the one-dimensional light modulation element is corrected based on the luminance distribution characteristic in the scanning direction to adjust the peak luminance at the time of light modulation. An image generating device. A one-dimensional light modulation element and its driving means, an optical scanning means for changing a formation position of a one-dimensional image obtained by light modulation using the one-dimensional light modulation element along a predetermined scanning direction, and a projection lens In an image projection apparatus provided with a projection optical system,
An image projection apparatus comprising: a control unit that controls an operation speed of the optical scanning unit in order to cancel a luminance change in the scanning direction based on the luminance distribution characteristic in the scanning direction. The image projection apparatus according to claim 6,
An image projection apparatus characterized in that drive control of the optical scanning means is performed such that the operation speed of the optical scanning means is slower in the peripheral area than in the center of the scanning range. The image projection apparatus according to claim 6,
An image projection apparatus comprising: a correction unit that performs correction processing related to image distortion by changing a modulation timing related to the one-dimensional light modulation element according to an operation speed of the optical scanning unit. The image projection apparatus according to claim 8,
The image projection apparatus, wherein the modulation timing is controlled such that the time interval of the modulation operation related to the one-dimensional light modulation element is shortened as the operation speed of the optical scanning unit increases. The image projection apparatus according to claim 6,
In order to reduce the luminance unevenness in the scanning direction, the driving signal of the one-dimensional light modulation element is corrected based on the luminance distribution characteristic in the scanning direction to adjust the peak luminance at the time of light modulation. An image projection device.

Images