JP4430364B2 - Line image scanning image display apparatus and display image distortion correction method - Google Patents

Description

  The present invention relates to a line image scanning image display apparatus and a display image distortion correction method. The line image scanning image display apparatus of the present invention can be used for a projection apparatus such as a projector, an in-vehicle navigator, and various displays.

  The light from each light modulation element in the “light modulation means having a number of minute light modulation elements arranged in a one-dimensional shape” is transmitted as object light by the imaging optical system, and is emitted from this imaging lens system. The image light beam is deflected in a direction orthogonal to the arrangement direction of the light modulation elements by the deflecting means, and the deflected light beam is imaged as a one-dimensional line image on the image display surface via the scanning optical system. There is known a “line image scanning image display device” that scans a display surface and displays a two-dimensional image on the image display surface (Non-Patent Document 1, Patent Document 1).

  As “light modulating means having a large number of minute light modulating elements arranged in one dimension”, GLV (grating light valve), LD array, and digital micromirror device have been widely known. (Both End Fixed Beam Light Valve) is also known (Patent Document 2).

  In such a line image scanning type image display device, when a “rectangular appropriate two-dimensional image” is optically obtained on a planar image display surface, the scanning optical system acting on the deflected light beam includes: A field curvature correction function, a distortion aberration correction function, and a constant speed function for making the scanning speed on the image display surface constant are required. It is extremely difficult to achieve all these functions optically well with a “scanning optical system having a small number of lenses”, and therefore the number of lenses constituting the scanning optical system increases.

  In the case of such a scanning optical system having a large number of lenses, the cost is increased due to the large number of lenses, and the scanning optical system is arranged at a position away from the deflecting means to cover the deflection range of the deflected light flux. The larger the lens, the larger the image display device itself.

  In the technical field of an optical scanning device known in relation to an optical printer or the like, a “technology for electrically correcting the constant speed characteristic of optical scanning” has been conventionally known (Patent Document 3).

  However, the field curvature cannot be corrected electrically, and conventionally, both the field curvature and the distortion are optically performed as in Patent Document 1, which increases the number of lenses of the scanning optical system. (For example, in the case described in Patent Document 1, the scanning optical system is composed of 3 to 5 lenses.).

Calibration of a Scanned Liner GLV Projection System R.W.Corrigan et.al.Silicon Light Machines JP 2002-131838 A JP 2002-214550 A Japanese Patent Laid-Open No. 14-277788

  In the line image scanning image display apparatus, the scanning optical system can be made simple and small, and an appropriate two-dimensional image can be displayed on the image display surface. It is an object of the present invention to realize cost reduction and downsizing of a display device.

The line image scanning type image display device of the present invention has a light modulation means, an imaging optical system, a deflection means, and a scanning optical system.
The “light modulating means” has a large number of minute light modulating elements arranged one-dimensionally. Each small light modulation element is responsible for displaying “one pixel”.
The “imaging optical system” is a one-dimensional line in a predetermined V direction perpendicular to the optical axis, which uses an array of light modulation elements in a light modulation means as an object, transmits a light beam from each light modulation element as object light, and It has a function of forming an image.

  That is, the longitudinal direction of the line image is the V direction. It goes without saying that the V direction corresponds to “the arrangement direction of the light modulation elements in the light modulation means”.

  In the light modulation means, a large number of light modulation elements are arranged one-dimensionally, but the arrangement is not limited to a one-row arrangement. For example, light modulation elements are arranged in three rows in parallel and close to each other. One row of the arrangement is an element row for red image display, another row is an element row for green image display, and the other row is blue. It can be an element array for image display. In such a case, three lines of red, green, and blue line images are formed in parallel and close to each other on the image display surface.

  The light modulation means may be a self-luminous type such as an LED array, or may be one in which a known BBLV or digital micromirror device is irradiated with light from an external light source according to Patent Document 2. .

The “deflecting means” deflects and scans the light beam emitted from the imaging optical system in the H direction orthogonal to the V direction.
The “scanning optical system” is an optical system that mainly corrects the curvature of field with respect to the light beam deflected by the deflecting unit and planarizes the image surface of the display image. The display image is actually displayed on a “planar image display surface”.

  As described above, since the imaging optical system has the function of “transmitting the light flux from each light modulation element as object light to form a one-dimensional line image”, the one-dimensional line image itself is formed. Although the image is formed by the image optical system, when the deflection is performed by the deflecting unit without using the scanning optical system, the image plane of the display image displayed by the scanning of the line image becomes a “cylindrical surface” instead of a plane. The scanning optical system uses such a cylindrical image surface as a field curvature, corrects this field curvature, planarizes the image surface of the display image, and matches the image display surface. Therefore, the scanning optical system must have a function of correcting the curvature of field and flattening the image plane of the display image.

The line image scanning image display apparatus according to claim 1 is characterized by the following points.
In other words, the scanning optical system has “refractive power” sufficient to correct the curvature of field , and is composed of N (1 ≦ N ≦ 2) lenses disposed close to the deflecting unit.
Further, the present invention has “light modulation element use number control means” for variably controlling the number A of light modulation elements used in the light modulation means in accordance with the position of the display image in the H direction.

The scanning optical system “corrects field curvature” includes the case where the scanning optical system corrects only field curvature and the case where it has other correction functions. Other correction functions include, for example, correction of constant velocity characteristics and distortion (since the line image formed by the imaging optical system is not bent, the distortion in this case is a distortion in the V direction. ) Correction.

The scanning optical system may not have “another correction function”, and the constant velocity characteristic correction function and the distortion aberration correction function may be those that slightly improve the constant velocity characteristic and the distortion aberration. The scanning optical system only needs to have “refractive power sufficient to correct curvature of field”. Therefore, the constant speed characteristic and distortion can be corrected within the above-described refractive power .

  In other words, since the scanning optical system does not have a sufficient distortion correction function, when the display surface is flattened by correcting the curvature of field, the “line image length” increases from the center in the H direction to the periphery. As it grows. This is the distortion in the V direction described above.

In the line image scanning type image display device of the present invention, in order to correct the deformation of the display image due to the distortion in the V direction, the number of light modulation elements used in the light modulation means: A is set in the H direction of the display image. The line image scanning image display apparatus according to claim 1 has “light modulation element use number control means” for executing this control.
Specifically, the “light modulation element usage number control means” can be set as a microcomputer or a part of its function.

The light modulation element use number control means of the line image scanning type image display apparatus according to claim 1 displays: “A use number of light modulation elements when scanning the peripheral part in the H direction of the display image: A (peripheral part)”. The number of uses when scanning the central portion in the H direction of the image is variably controlled to be less than A (central portion). In this case, the light modulation element usage number control means can be variably controlled such that “the number of light modulation elements used: A is gradually decreased from the center to the periphery of the display image”. The number of uses: A is changed by thinning out the pixel modulation signal in the image signal applied to the light modulation means in a predetermined relationship with the position in the H direction of the display image as it goes from the center in the H direction to the periphery. At the same time, the “display pixel that has not been thinned out” on the side farther from the optical axis of the imaging optical system than the thinned display pixel is parallel to the optical axis side of the imaging optical system in the V direction. It can be variably controlled so that the light modulation elements corresponding to the pixels farthest from the optical axis of the imaging optical system are sequentially shifted to the non-use state.

Depending on the direction and configuration of the scanning optical system, the “end position of the line image” may not be simply increased but may be partially lowered when scanning the middle part in the H direction. It is possible to correct the distortion of the length of the line image by reducing the rate of decrease of A. Even at this time, it is desirable from the viewpoint of overall performance to set “reducing the number of uses: A in the peripheral portion” as described in claim 1 , and the distortion is corrected by reducing the number of pixels.

In addition, as described in claim 2 , the number of uses: A is gradually decreased from the central portion in the H direction toward the peripheral portion, even if the aspherical surface is not frequently used or used frequently in the scanning optical system. This is effective as a correction method in the case where a very high-order term is not used or in the case of field curvature correction mainly using a spherical surface.

In the case of claim 3, the brightness of the line image is lowered because the “number of pixels in the V direction” is reduced by the thinned out pixels, but the distortion in the V direction is about 10% or less in normal correction, The decrease in brightness is inconspicuous even if ignored in practice. When a decrease in brightness is a problem, it can be dealt with by changing the brightness of the light source in synchronization with the scanning of the line image.

The "imaging optical system" in the line image scanning type image display device according to any one of claims 1 to 3 , wherein the light modulation element side is telecentric and has a substantial aperture near the deflecting means. preferable. In this case, the imaging optical system can be “a configuration in which a group of a single lens having a strong positive power and a group of three or more lenses is arranged sequentially from the light modulation means side to the deflection means side”. .

Ordinary light modulation elements often have “directivity that maximizes light emission in the direction orthogonal to the array”, but as described in claim 4 , by making the light modulation element side of the imaging optical system telecentric, It is possible to reduce “inconsistency” in light capture from each light modulation element and to reduce “brightness unevenness” in the longitudinal direction (V direction) of the line image. In addition, by having a substantial aperture in the vicinity of the deflecting means, the deflecting portion of the deflecting means can be set small, and “variation in deflection” and “driving power / power consumption” can be reduced, leading to energy saving.

When the imaging optical system is configured as described in claim 5, the single lens having a strong positive power is extremely effective for telecentric configuration of the light modulation element side, and the light at the directional center of each light modulation element is reflected in the pupil. It plays a role of guiding to the vicinity of the center. Of course, it is possible to divide this part into two or more lenses and reduce the power of each lens to improve the workability.

  In addition, the “group of three or more lenses” of the imaging optical system in the case of claim 5 is a part that largely determines the reproduction of pixels after the scanning optical system. In particular, when used in white light / multicolor light and “when chromatic aberration correction is required”, a configuration of three or more is essential. This group corrects paraxial chromatic aberration, spherical aberration, astigmatism in the V direction, coma aberration, and chromatic aberration of magnification, and simplifies the scanning optical system by sharing much of the image performance.

6. The “single lens having a strong positive power arranged on the light modulation means side” of the imaging optical system in the line image scanning image display device according to claim 5 has at least one surface close in the V direction and the H direction. Preferably, the toroidal surface or “special toroidal surface” has substantially the same axial curvature. By applying such a surface to the lens arranged on the side of the light modulation element where the light rays are separated at the angle of view, the sagittal image plane can be controlled relatively independently. This is effective when the image forming optical system is required to have a wide-angle and bright specification. The special toroidal surface will be described later.

The “scanning optical system” in the line image scanning image display device according to any one of claims 1 to 6 can have “overcorrected field curvature” in both the V direction and the H direction ( In this case, the scanning optical system can be configured as “a single lens in which at least one surface is a coaxial aspheric surface” ( claim 8 ).

  In the line image scanning type image display device of the present invention, an anamorphic image plane having a radius of the distance between the starting point of deflection by the deflection means and the image plane is displayed on the display image obtained by scanning the line image without using the scanning optical system. Curvature (cylindrical surface shape) occurs. Accordingly, the first role of the “scanning optical system” is to correct such an anamorphic curvature of field, but if the correction is performed with an anamorphic surface having no power in the H direction, the image plane in the H direction cannot be corrected. Therefore, the scanning optical system needs to have an excessively corrected field curvature in both the V direction and the H direction. In order for the field curvature of the entire optical system to be good, it is preferable that the field curvature in the V direction of the imaging optical system is insufficiently corrected.

As described in claim 8 , the scanning optical system is “a single lens having at least one surface as a coaxial aspheric surface”, so that the optical performance as the scanning optical system can be realized in the entire scanning area while the number of constituent elements is minimum. it can. Of course, both surfaces can be aspherical or can be used in accordance with the specifications, such as a two-sheet configuration.

The line image scanning image display device according to any one of claims 1 to 8 , wherein the deflection means is a "galvano mirror (an optical deflector whose mirror surface deflection angle is sinusoidally oscillated)" and "the display image H toward the periphery from the center in the direction, the modulation time of one pixel in the light modulation means may comprise an image signal processing means for processing the image signal so as "to increase pixel line basis (claim 9). The “pixel line” is a so-called one-dimensional array of light modulation elements in the light modulation means.
The line image scanning image display apparatus according to any one of claims 1 to 8 , wherein the deflecting means is a "polygon mirror", and "light modulation is performed from the central portion to the peripheral portion in the H direction of the display image." It may have an image signal processing means for processing the image signal of one pixel of the modulation time shortening by pixel line unit "as in section (claim 10).

The “image signal processing means” according to claims 9 and 10 can be specifically set as a microcomputer or a part of its function, and can be realized by the same microcomputer as the above-mentioned “light modulation element use number control means”.

The line image scanning image display apparatus according to any one of claims 1 to 10 can display a display image on a screen "separate from the line image scanning image display apparatus". may have as a part of the device "display image screen as an image display surface for forming an image of" (claim 11), in this case, one or more folding mirrors the light path between the scanning optical system and the screen It can be set as the structure bent by ( claim 12 ). By integrating the screen in this way, a rear projection type image display apparatus can be realized with high performance, light weight and low cost.

The “display image distortion correction method” according to the present invention is a method for correcting distortion in the V direction of a display image in the line image scanning image display apparatus according to claim 3, wherein the display image is centered in the H direction. The number of uses: A was changed by thinning out the pixel modulation signal in the image signal applied to the light modulation means in a predetermined relationship with respect to the position in the H direction of the display image as it moved from the peripheral portion to the peripheral portion, and was not thinned out The display pixels are sequentially shifted to the optical axis side of the imaging optical system, and are variably controlled so that the light modulation elements corresponding to the pixels farthest from the optical axis of the imaging optical system are sequentially in a non-use state.

  As described above, in the present invention, what is required of the scanning optical system is “mainly the function of correcting the curvature of field”, and the refractive power required for this is very small. It can be composed of two lenses and these can be arranged close to the deflection means. Accordingly, the scanning optical system can be realized in a compact and inexpensive manner, and the line image scanning image display apparatus can be realized in a low cost and in a compact manner.

  Further, by using the “light modulation element use number control means”, the number of use of the light modulation elements in the light modulation means: A is variably controlled according to the position of the display image in the H direction, so that the distortion aberration in the V direction can be electrically It is possible to correct the image and display a good display image.

According to the ninth and tenth aspects of the present invention, the image signal processing means “adjusts the modulation time of one pixel in the light modulation means in units of pixel lines as it goes from the central portion to the peripheral portion in the H direction of the display image”. Accordingly, it is possible to reduce or correct the distortion of the display image due to the non-constant speed of scanning in the H direction of the line image.

An embodiment of a line image scanning image display apparatus will be described with reference to FIG.
In FIG. 1A, reference numeral 10 denotes an illumination optical system, reference numeral 20 denotes an optical modulator, reference numeral 30 denotes an imaging optical system, reference numeral 40 denotes deflection means, reference numeral 50 denotes a scanning optical system, and reference numeral 60 denotes an image display surface. .
The light modulator 20 is a self-light-emitting type and requires illumination means, and the illumination optical system 10 and the light deflector 20 constitute “light modulation means”.

  The illumination optical system 10 transmits light from a lamp 11 having a “linear light source” such as a halogen lamp into a modulation region of the light modulator 20 by a reflecting mirror 12 and a cylindrical lens 13 as shown in FIG. ) In the shape of a slit whose longitudinal direction is the direction orthogonal to the drawing. The linear light emission source of the lamp 11 has a light emission length slightly longer than the modulation region length of the light modulator 20. The cross-sectional shape of the reflecting mirror 12 may be an ellipse, a non-arc including a parabola or a higher-order term in addition to a circular shape.

  The light modulator 20 has BBLV, which is a reflection type light modulation element, arranged in a direction orthogonal to the drawing in FIG. As shown in the left diagram of FIG. 1C, BBLV, which is a light modulation element, fixes a flexible strip-shaped reflecting member 22 on one side of a substrate 21 having a V-shaped groove. The light shielding plate 23 having an opening and the color filter 24 are integrated by an appropriate joining method.

  The left figure of FIG.1 (c) is the use state of "light modulation ON", and the illumination light L irradiated is reflected by the strip-shaped reflection member 22, passes through the opening of the light-shielding plate 23 as image light L0, and a color filter 24 is separated into colors. The right diagram in FIG. 1C shows a state in which “light modulation is off” is not used, the strip-shaped reflecting member 22 is bent along the V-shaped groove, and the reflected light is blocked by the light blocking plate 23.

  The ON / OFF of each strip-shaped reflecting member represents information of one pixel, but the size corresponding to one pixel in the optical modulator is 19 μm × 20 μm, the direction of 19 μm width is the arrangement direction of the light modulation elements, and the arrangement pitch Is 20 μm.

  In the optical modulator 20, the light modulation elements based on BBLV as described with reference to FIG. 1C are arranged in three rows as shown in FIG. The array LR in the light modulation element 20 is for expressing image information of red, the array LG is green, and the array LB is blue. The reflected light is color-separated by red, green, and blue color filters, respectively. The number of the light modulation elements in each array is 768, and the array length of the light modulation elements is 15.36 mm (19 μm × 768).

  In the embodiment of FIG. 1, one row of light modulation elements corresponds to each color of red, green, and blue. However, each color may be constituted by a plurality of rows of light modulation elements, and instead of a color filter. The three colors of illumination light may be condensed on the light modulation element array. The illumination optical system 10 is not necessary if it is a self-luminous light modulation means such as an EL array, LED array, or LD array.

  As will be described later in the embodiment, the imaging optical system 30 is composed of a plurality of lenses. However, in order to make the optical modulator 20 side telecentric, a positive lens with relatively high power is provided on the optical modulator 20 side. It is used. When the center of directivity is parallel to the optical axis, the light beam emitted from each light modulation element can be taken in effectively toward the entrance pupil of the imaging optical system 30, and the brightness in the light modulation element array direction Unevenness can be reduced.

  Further, as shown in the embodiment, a “three-lens lens group” is used after the positive lens having strong power. Considering only the imaging optical system, it is a “behind diaphragm with a rear-end diaphragm”, but technically, it is a lens system that is classified as a front diaphragm according to the “conventional way of using the reduction conjugate side as the image plane”. Become.

  The light modulator 20 is arranged in a “full shift state” with respect to the imaging optical system 30, and “light modulation element at one end” of the array of light modulation elements in a direction orthogonal to the drawing of FIG. Is positioned at the optical axis position of the imaging optical system 30.

  The imaging optical system 30 has a focal length of 36 mm and a conjugate length of 1.5 m, and forms a 39 times magnified image on the image display surface 60 (actually a screen surface). Accordingly, the light from the light modulation element array having the arrangement length of 15.36 mm in the light modulator 20 is formed as a “line image” having a length of 600 mm in the direction orthogonal to the drawing of FIG. The longitudinal direction of this line image (the direction perpendicular to the drawing in FIG. 1A) is the V direction.

  In the embodiment of FIG. 1, a “galvanomirror that vibrates sinusoidally with a maximum deflection angle of 15 degrees” is used as the deflecting means 40. Since the “substantial aperture” is provided in the vicinity of the deflecting means 40, the effective diameter of the deflecting mirror surface of the deflecting means can be minimized, and the accuracy of rotational driving can be improved and the driving power can be reduced.

Since the deflection means 40 is a galvanometer mirror, the incident angle of the light beam incident on the deflection surface oscillates sinusoidally in time. Therefore, in order to “optically equalize” the movement of the line image in the H direction on the image display surface 60, the image height in the H direction: h, the incident angle: θ, and the distance to the image surface: L are: ,
h = L · sin ⁻¹ (θ)
"H direction distortion correction (constant velocity correction)" is required.

  That is, in the embodiment of FIG. 1, if the scanning optical system 50 performs “such distortion correction”, the movement of the line image can be made optically uniform, but in this embodiment, scanning is performed. Since the optical system 50 is given “mainly a slight refractive power sufficient to correct curvature of field”, the above-described constant velocity correction by the scanning optical system 50 is not substantially performed, and the constant velocity correction is requested. Item 10. “Image signal processing means for processing an image signal so that the modulation time of one pixel in the light modulation means becomes longer in units of pixel lines from the center to the periphery in the H direction of the display image” And do it electrically.

  When the effective deflection angle of the galvanometer mirror 40 is ± 8.2 degrees with respect to the angle of the optical axis of the imaging optical system: 45 °, ± 400 mm (== 400 mm on the image display surface 60 1.4 m away from the mirror) When a line image scan with a width of 800 mm is performed, a linearity of -7.5% occurs at the outermost peripheral portion of the scan.

This linearity correction is performed as follows.
In the high frequency clock generation circuit 78 shown in FIG. 1A, a “high frequency clock eight times the pixel clock” is generated, and the high frequency clock is divided by the frequency dividing circuit 76 to generate the pixel clock. The fact that the linearity is negative on the peripheral side of scanning means that the scanning speed is too slow compared with the central part, so that m pixel clocks having a time width of 8/8 are included in m + n pixel lines. The time width: 9/8 pixel clocks are set to n, the scanning length of the pixel line by the time width: 9/8 pixel clocks is made relatively large, and linearity correction is performed by distributing the number of clocks m and n. Is possible.

For example, when correcting the linearity of -7.5% above,
1 / (1-7.5%) = 1 / (1-0.075) = {m + (9n / 8)} / (m + n)
Therefore, m = 9, n = 19, and m + n = 25 satisfy this relationship.

  Therefore, when 25 pixel line signals are output, a rule is used in which a pixel clock having a time width of 8/8 is repeated 9 times and a pixel clock having a time width of 9/8 is repeated 16 times in an appropriate arrangement. Thus, it is possible to correct a constant velocity deviation (= pixel line equal interval deviation) due to a linearity of −7.5%.

  When scanning a line image in the H direction, the linearity changes continuously, but the scanning area is divided into multiple areas, and the size of each area is determined so that the linearity changes in each area are approximately the same. By adjusting the mixing ratio of the pixel clocks having different time widths as described above for each of these areas, the linearity can be effectively corrected in the entire scanning region. This correction method is in principle the same as the method described in Patent Document 3.

FIG. 2 is a diagram for explaining correction of distortion in the V direction.
As described above, in the embodiment of FIG. 1, the light modulator 20 is arranged in a full shift state with respect to the imaging optical system 30, and in the direction orthogonal to the drawing of FIG. The light modulation element at one end of the array is positioned on the optical axis of the imaging optical system 30.

  FIG. 2A shows the state of a display image displayed by forming a line image on the image display surface in this state and scanning it in the H direction. In the figure, the vertical axis represents the V direction, that is, “the longitudinal direction of the line image”, and the horizontal axis represents the H direction, that is, the scanning direction. Note that the V direction is drawn smaller than the H direction.

  In the V direction, when the optical modulator 20 is in a full shift state with respect to the imaging element 30, the “imaging position locus (scanning line)” of the light from the optical modulation element at one end of the optical modulation element array is It becomes a straight line like the horizontal line SL0 of V = 0 in FIG. However, as the value of V increases, the scanning line bends in a “downwardly convex arcuate shape”, and the scanning line of light from the light modulation element at the other end becomes as shown by a curve SL1 in FIG. The V coordinate of the scanning line SL1 is 600 mm at H = 0 (the image formation position of the line image when the deflection mirror of the galvano mirror is at 45 degrees), but at H = ± 200 mm, V = 606.8 mm. , H = ± 400 mm (the image formation position of the line image when the deflection mirror is at the reference position ± 8.2 degrees), V = 630.8 mm.

That is, a line image formed by the arrangement of 768 light modulation elements in the optical deflector 20 is formed to a length of 630.8 mm when H = ± 400. This is because the length of the line image at H = 0: 600 mm,
600 / 630.8 = 0.9512≈0.95 = 19/20
19:20.

That is, the array for 19 light modulation elements at H = 0 is expanded to the array for 20 at H = ± 400. Therefore, when a line image is formed at a position of H = ± 400 mm, adjacent ones are arranged so as to make an “off state” by thinning one out of every 20 light modulation element arrays, and to make up for the off state portion. The pixels to be shifted are sequentially shifted in the optical axis direction (the direction of V = 0), and among the 768 pieces, “38 pieces in the peripheral portion are set to an unused state”
630.8. (768-38) /768=599.59≈600 mm
Thus, the length of the line image at H = ± 400 mm of the object represented by the 730 light modulation elements in use other than the peripheral portion can be corrected to 600 mm.

  Similarly, the length of the line image at an arbitrary H position is V (H), and the “decimation number” of the light modulation element is determined according to V (H) / V (0). If the line image is displayed on the “light modulation element in use” except for the light modulation element in the peripheral part, the length of the line image is made substantially constant over the display area in the H direction of the line image. Can be aligned. Note that the pixels to be thinned out may be thinned out at regular intervals or randomly.

For example, the length of the line image at H = ± 200 mm is 606.8 mm.
600 / 606.8 = 0.9888≈0.99 = 99/100
Therefore, by thinning out one out of every 100 light modulation element arrays, by making the light modulation elements in the peripheral portion out of 768 into a non-use state,
606.8 · (768-8) /768=600.48≈600
Thus, the length of the line image can be corrected to 600 mm.

  The length of the line image: The change of V (H) due to H is not uniform. However, practically, “correction of the same rule (for example, with increasing H, the pixel decimation number increases linearly or equally) The correction of the rule to be performed) can also reduce the distortion of the displayed image, and such correction of the same rule can be performed relatively easily.

  In FIG. 2B, the “cells arranged in the V direction” are modeled images of the light modulation elements of the light modulator. The hatched meshes indicate “pixels to be thinned out”, and the arrows indicate that pixels adjacent to the thinned pixels are sequentially shifted in the optical axis direction of the imaging optical system. FIG. 2C shows a state in which pixels that have been thinned out and are not in use are collected at the periphery of the line image. A frame indicated by a broken line in FIG. 2C indicates the “contour of the display image” corrected as described above.

  As described above, the reduction of the distortion of the display image due to the scanning of the line image has been described. However, the “correction of the pixel interval in the V direction including the distortion in the V direction of the imaging optical system” is included in the above correction and executed simultaneously. Is also possible.

  The above-mentioned “number of use of light modulation elements in light modulation means: A (number obtained by subtracting the number of light modulation elements in an unused state from the number of light modulation elements arranged) is variably controlled according to the position of the display image in the H direction. The means for controlling the number of used light modulation elements includes the frame memory 72 and the image processing unit 74 shown in FIG.

  That is, from the image information stored in the frame memory 72 (information for determining on / off of the light modulation element according to each pixel), the pixel to be thinned is determined for each information of one line of the light modulation element array. The information after thinning is made continuous (performed by sequentially shifting adjacent pixels of the thinned pixels in the optical axis direction of the imaging optical system) and input to the modulation circuit 70 as image information of one line image.

In this way, the pixel modulation signal in the image signal applied to the light modulation means is thinned out with a predetermined relationship with respect to the position in the H direction of the display image as it goes from the center in the H direction to the periphery in the display image. Number: A is changed, and display pixels that have not been thinned out are sequentially shifted toward the optical axis side of the imaging optical system so that the pixels that are farthest from the optical axis of the imaging optical system are sequentially in a non-use state. A “display image distortion correction method ” is variably controlled.

  Hereinafter, specific examples of the imaging optical system and the scanning optical system will be described.

  In each of the embodiments, the imaging optical system has a strong positive power, and the second surface counted from the optical modulator side has a non-arc shape in the XZ plane (a plane parallel to the drawing of FIG. 1A). A single lens which is a “curved axis toroidal surface” having the above is arranged on the optical modulator side, and a four lens group is arranged on the deflecting means side. As shown in FIG. 1A, the galvanometer mirror as a deflecting means has a state in which the deflecting mirror is inclined 45 degrees with respect to the optical axis of the imaging optical system as a reference position, and the light beam from the optical modulator side is bent at a right angle. Is incident on the scanning optical system.

“Aspherical surface” has coordinates of optical axis direction: X, V direction: Y, H direction: Z, paraxial radius of curvature in V direction: Rv, paraxial radius of curvature in H direction: Rh, reciprocal of radius of curvature. A well-known formula obtained by rotating the non-arc shape of the cross section in the V direction (XY plane) about the X axis using the curvature (C = 1 / R):
X = Cv · Y ² / [1 + √ {1− (Kv + 1) · Cv ² · Y ² }] + a ₀₄ · Y ⁴ + a ₀₆ · Y ⁶
+ A ₀₈・ Y ⁸ + a ₁₀・ Y ¹⁰ + a ₁₂・ Y ¹²
It expresses with.

The “special toroidal surface” is a curved-axis toroidal surface having a non-arc shape in the XZ plane, and a term whose curvature changes in the Y direction.
_{Cs = Ch + b 02 · Y} 2 + b 04 · Y 4 + b 06 · Y 6 + b 08 · Y 8 + b 10 · Y 10 + b 12 · Y 12
Use
X = Cv · Y ² / [1 + √ {1− (Kv + 1) · Cv ² · Y ² }] + a ₀₄ · Y ⁴ + a ₀₆ · Y ⁶
+ A ₀₈・ Y ⁸ + a ₁₀・ Y ¹⁰ + a ₁₂・ Y ¹²
+ Cs · Z ² / [1 + √ {1- (Kh + 1) · Cs ² · Z ² }]
+ (D ₀₀ + d ₀₂ · Y ² + d ₀₄ · Y ⁴ + d ₀₆ · Y ⁶ + d ₀₈ · Y ⁸ + d ₁₀ · Y ¹⁰ + d ₁₂ · Y ¹² ) · Z ⁴
It is expressed by In each example, Kv = Kh = 0.

The scanning optical system is a double-sided aspherical single lens.
No. Description of surface Rv d Nd νd
00 Light modulation element 0.0 16.862
01 Spherical surface 69.644 9.37 1.70091 54.52
02 Special toroidal surface -34.451 6.06
03 Spherical surface 18.604 5.87 1.69680 55.46
04 Spherical surface 88.046 1.517
05 Spherical surface -91.461 0.8 1.77737 25.53
06 Spherical surface 17.198 7.04
07 Spherical surface -14.087 3.78 1.84666 23.78
08 Spherical surface -17.821 0.1
09 Spherical surface 500.000 3.29 1.69680 55.46
10 Spherical surface -26.321 7.0
11 Deflection surface 0.0 10.0
12 Aspheric surface 48.188 3.0 1.53046 55.84
13 Aspherical surface 49.361.

Second surface: curved axis toroidal surface having a non-arc shape in the XZ plane
Rh = -34.451
Surface factor
0/8 order 2/10 order 4/12 order 6th order
a 5.447E-06 -7.842E-09
3.277E-11 -6.611E-14 5.638E-17
b 2.775E-05 -1.534E-07 9.445E-10
-4.788E-12 1.215E-14 -1.159E-17
d 6.774E-06 7.249E-08 -6.972E-09 1.097E-10
-7.184E-13 2.086E-15 -2.222E-18.

12th surface: Aspheric surface coefficient
0/8 order 2/10 order 4/12 order 6th order
a 2.389E-06 -3.456E-08
3.672E-10 -1.869E-12 2.591E-15
13th surface: Aspheric surface coefficient
0/8 order 2/10 order 4/12 order 6th order
a 2.816E-06 -3.374E-08
3.168E-10 -1.402E-12 1.727E-14.

  Entrance pupil position: infinity from light modulator, object side NA = 0.183, half angle of view = 24.2 °, effective deflection angle of galvano mirror: ± 8.2 °, ray deflection range: ± 16.4 ° , H direction scanning length: ± 400 mm.

  FIG. 3 shows lens configurations of the imaging optical system and the scanning optical system of Example 1. (A) is a figure in XY plane, (b) is a figure in XZ plane. Reference symbol L1 is “a single lens having a strong positive power, and the second surface is a“ curved axis toroidal surface ”having a non-arc shape in the XZ plane as counted from the optical modulator side, reference symbol 40 is a galvanometer mirror, L6 indicates a single lens constituting the scanning optical system. The optical modulator 20 is completely shifted in the XY cross section and is disposed below the optical axis.

  FIG. 4 shows a distortion diagram for Example 1, and FIG. 5 shows an MTF characteristic diagram. MTF is a calculated value of a wave optical system in which a weight of 2: 1: 1 is applied to d-line (587.6 nm), g-line (435.8 nm), and He—Ne laser light (632.8 nm). The three figures are H = 0.0, H = ± 200, and H = ± 400 on the image display surface, respectively. In each figure, the characteristics at V = 0.0, V = 300, and V = 600 are shown on the Y axis. Are displayed with MTF and defocus on the X-axis. The solid line is the “V direction”, and the broken line or the chain line is the “H direction”. The plotted frequency is Nyquist 0.64 lines / mm.

The scanning optical system is two lenses composed only of a spherical surface.
No. Description of surface Rv d Nd νd
00 Light modulation element 0.0 18.12
01 Spherical 86.342 7.84 1.70091 54.52
02 Special toroidal surface -36.641 6.06
03 Spherical surface 18.220 5.87 1.69680 55.46
04 Spherical surface 85.420 1.26
05 Spherical surface -139.68 0.8 1.77737 25.53
06 Spherical surface 17.203 6.33
07 Spherical surface -14.226 3.78 1.84666 23.78
08 Spherical surface -17.795 0.1
09 Spherical surface 437.695 3.29 1.69680 55.46
10 Spherical surface -27.978 7.0
11 Deflection surface 0.0 7.0
12 Spherical surface 51.922 3.0 1.53046 55.84
13 Spherical surface 52.054 7.0
14 Spherical surface -133.97 3.0 1.53046 55.84
15 spherical surface -122.02.

Second surface: curved toroidal surface having an aspherical surface in the XZ plane
Rh = -36.641
Surface factor
0/8 order 2/10 order 4/12 order 6th order
a 5.084E-06 -6.252E-09
1.914E-11 -3.080E-14 1.762E-17
b 2.404E-05 -7.583E-08 3.212E-10
-2.835E-12 1.148E-14 -1.512E-17
d 5.255E-06 1.019E-07 -6.173E-09 9.952E-11
-7.186E-13 2.349E-15 -2.841E-18.

  Entrance pupil position: 370 mm from optical modulator, effective deflection angle of galvano mirror: ± 8.3 °, beam deflection range: ± 16.6 °, H direction scanning length: ± 400 mm. Others are the same as Example 1.

  FIG. 6 shows the lens configuration of the imaging optical system and the scanning optical system of Example 2 in the same manner as FIG. Reference numerals L6 and L7 indicate two spherical lenses constituting the scanning optical system. In addition, distortion diagrams and MTF characteristic diagrams relating to Example 2 are shown in FIGS. 7 and 8, respectively, following FIGS. 4 and 5.

  FIG. 9 shows an example in which a “polygon mirror” is used as the deflecting means 41 in the embodiment shown in FIG. In this case, the constant velocity characteristic is the fθ characteristic, but it can be corrected by applying a method similar to the method of the first embodiment.

  FIG. 10 is a modification of the embodiment shown in FIG. 1, and includes a screen SC as an image display surface on which a display image is formed, and an optical path between the scanning optical system 50 and the screen SC is set to one or more. It is configured to be bent by a folding mirror ML.

  The line image scanning image display apparatus shown in FIG. 1 (FIG. 9) has light modulation means 10 and 20 having a large number of minute light modulation elements arranged in a one-dimensional manner, and the light modulation means. An imaging optical system 30 that uses the arrangement of the light modulation elements in FIG. 5 as an object, transmits a light beam from each of the light modulation elements as object light, and forms an image as a one-dimensional line image in a predetermined V direction. Deflection means 40 (41) that deflects and scans the light beam emitted from the system 30 in the H direction orthogonal to the V direction, and the curvature of field is mainly corrected for the light beam deflected by this deflection means, and the display image is displayed. A scanning optical system 50 for flattening the image plane, and the scanning optical system 50 has a slight refractive power that is mainly sufficient to correct curvature of field, and is arranged close to the deflecting means N (1 ≦ N ≦ 2) Consists of lenses, and in the light modulation means Light modulation element use number control means 72, 74 for variably controlling the number of light modulation elements used: A (number obtained by subtracting the thinning number from the number of light modulation element arrays) according to the position in the H direction of the display image. (Claim 1).

The light modulation element use number control means 72 and 74 scan the center part in the H direction of the display image with the use number A (peripheral part) of the light modulation element when scanning the peripheral part in the H direction of the display image. The number of times used is variably controlled so as to be smaller than A (center portion), and the number of uses: A is variably controlled so as to gradually decrease from the center portion to the peripheral portion of the display image.

The light modulation element usage number varying means 72 and 74 also convert the pixel modulation signal in the image signal applied to the light modulation means to the position in the H direction of the display image as it goes from the center to the periphery in the H direction of the display image. The number of uses: A is changed by thinning out in a predetermined relationship, and the display pixels that are not thinned out are sequentially shifted toward the optical axis side of the imaging optical system so as to be the farthest pixel from the optical axis of the imaging optical system 30 Are controlled so as to be in a non-use state in order from the light modulation element corresponding to . The imaging optical system 30 is telecentric on the light modulation means side and has a substantial stop near the deflection means.

In addition, the imaging optical systems of Examples 1 and 2 listed above are a group consisting of a single lens L1 having a strong positive power and three or more lenses sequentially from the light modulating means side to the deflecting means side. the result was placed, at least one surface of the single lens having a strong positive power disposed on the light modulating means side L1 (second surface) is a special toroidal surface, also the scanning optical system in these embodiments has overcorrection of field curvature in the V direction · H direction both the scanning optical system in example 1 is a single lens having both surfaces are coaxial aspherical.

In the line image scanning image display apparatus of FIG. 1, the deflecting means 40 is a galvanometer mirror, and the modulation time of one pixel in the light modulating means is changed in units of pixel lines from the center to the periphery in the H direction of the display image. in an image signal processing unit 76, 78 for processing the image signal so as to increase. In the line image scanning image display apparatus of FIG. 9, since the deflecting means 41 is a polygon mirror, the image signal processing means 76 and 78 are light modulating means as they move from the central portion to the peripheral portion in the H direction of the display image. The image signal is processed so as to shorten the modulation time of one pixel in each pixel line.

Further, the line image scanning image display apparatus shown in FIG. 10 has a screen SC as an image display surface on which a display image is formed, and an optical path between the scanning optical system 50 and the screen SC is It is configured to be bent by a single folding mirror ML.

It is a figure for demonstrating embodiment of a line image scanning type image display apparatus. It is a figure for demonstrating the characterizing part of invention. FIG. 3 is a diagram illustrating lens configurations of an imaging optical system and a scanning optical system in Example 1. FIG. 4 is a diagram showing distortion aberration of Example 1. FIG. 3 is a diagram showing an MTF characteristic diagram of Example 1. FIG. 6 is a diagram illustrating lens configurations of an imaging optical system and a scanning optical system of Example 2. 6 is a diagram showing distortion aberration of Example 2. FIG. FIG. 6 is a diagram showing an MTF characteristic diagram of Example 2. It is a figure for demonstrating another form of implementation of a line image scanning type image display apparatus. FIG. 11 is a diagram schematically showing only another characteristic part of another embodiment of the line image scanning image display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Illumination optical system 20 Optical modulator 30 Imaging optical system 40 Deflection means 50 Scanning optical system

Claims (13)

A light modulation means having a large number of minute light modulation elements arranged one-dimensionally;
Using the arrangement of the light modulation elements in the light modulation means as an object, the light flux from each of the light modulation elements is transmitted as object light and formed as a one-dimensional line image in a predetermined V direction perpendicular to the optical axis . An imaging optical system having a function ;
Deflecting means for deflecting and scanning the light beam emitted from the imaging optical system in the H direction orthogonal to the V direction, and changing the imaging position of the line image into a cylindrical surface ;
A scanning optical system that performs field curvature correction with a cylindrical imaging surface formed by the light beam deflected by the deflecting means as field curvature, and planarizes the cylindrical imaging surface ;
The scanning optical system is composed of N (1 ≦ N ≦ 2) lenses having a refractive power for correcting the curvature of field and disposed in proximity to the deflecting unit,
A light modulation element use number control means for variably controlling the number of light modulation elements used in the light modulation means: A according to the position of the display image in the H direction;
The light modulation element usage number control means scans the central portion of the display image in the H direction with the use number A (peripheral portion) of the light modulation element when scanning the peripheral portion in the H direction of the display image. Number of times of use: A line image scanning image display device variably controlled so as to be less than A (center portion) . The line image scanning image display device according to claim 1,
The line image scanning image display characterized in that the light modulation element use number control means variably controls the use number A of the light modulation element so as to gradually decrease from the central part to the peripheral part of the display image. apparatus. The line image scanning type image display device according to claim 2,
The light modulation element use number variable means is
The number of uses: A is changed by thinning out the pixel modulation signal in the image signal applied to the light modulation means in a predetermined relationship with the position in the H direction of the display image as it goes from the center to the periphery in the H direction of the display image. In addition, the display pixels on the side farther from the optical axis of the imaging optical system than the thinned display pixels and not thinned out are sequentially shifted in parallel to the V direction toward the optical axis, A line image scanning type image display apparatus variably controlled so that light modulation elements corresponding to pixels farthest from the optical axis of the imaging optical system are sequentially in a non-use state . The line image scanning image display apparatus according to any one of claims 1 to 3,
  A line image scanning image display apparatus characterized in that the imaging optical system is telecentric on the light modulation means side and has a substantial aperture near the deflection means. The line image scanning image display device according to claim 4,
A line image scanning characterized in that the imaging optical system comprises a single lens having a positive power and a lens group composed of three or more lenses sequentially from the light modulating means side to the deflecting means side. Type image display device. The line image scanning image display device according to claim 5,
Whether at least one surface of a single lens having positive power arranged on the light modulation means side is a toroidal surface having substantially the same paraxial curvature in the V direction and the H direction,
Alternatively, the line image scanning image display device is a curved axis toroidal surface having a non-arc shape in a plane including the optical axis direction and the H direction . In the line image scanning image display device according to any one of claims 1 to 6,
A line image scanning type image display apparatus comprising a scanning optical system that planarizes a cylindrical imaging surface obtained by scanning a line image by overcorrecting field curvature in both the V direction and the H direction . The line image scanning image display device according to claim 7,
A line image scanning image display apparatus, wherein the scanning optical system is a single lens having at least one surface that is a coaxial aspheric surface . In the line image scanning image display device according to any one of claims 1 to 8,
  The deflection means is a galvanometer mirror,
  A line having image signal processing means for processing an image signal so that the modulation time of one pixel in the light modulation means becomes longer in units of pixel lines from the central portion to the peripheral portion in the H direction of the display image. Image scanning image display device. In the line image scanning image display device according to any one of claims 1 to 8,
The deflecting means is a polygon mirror;
A line having image signal processing means for processing an image signal so as to shorten the modulation time of one pixel in the light modulation means in units of pixel lines from the central portion in the H direction to the peripheral portion of the display image. Image scanning image display device . In the line image scanning image display device according to any one of claims 1 to 10,
  A line image scanning image display device comprising a screen as an image display surface for forming a display image. The line image scanning image display device according to claim 11,
A line image scanning image display apparatus, wherein an optical path between a scanning optical system and a screen is bent by one or more folding mirrors . The line image scanning image display device according to claim 3, wherein the display image is corrected in the V-direction distortion.
  The number of uses: A is changed by thinning out the pixel modulation signal in the image signal applied to the light modulation means in a predetermined relationship with the position in the H direction of the display image as it goes from the center to the periphery in the H direction of the display image. In addition, the display pixels that have not been thinned out are sequentially shifted to the optical axis side of the imaging optical system, and the light modulation elements corresponding to the pixels farthest from the optical axis of the imaging optical system are sequentially set to the unused state. A display image distortion correction method characterized by variably controlling the display image as described above.

Images