Method for adjusting and inspecting optical modules

Abstract

In the present invention, at least three beams of light in a test pattern projected from an optical module 1 are acquired by a wavefront sensor 9, the degree of parallelism of each beam is calculated, and the posture of a display panel 5 of the optical module is adjusted so that the degrees of parallelism of the beams match.

Description

Technical Field

[0001] The present disclosure relates to a method for adjusting and inspecting an optical module that projects light or an image.

Background Art

[0002] Patent Document 1 discloses an adjustment device for an optical module of a liquid crystal projector. This adjustment device for the optical module adjusts and fixes the position and orientation of a liquid crystal panel mounted on the optical module in order to suppress blurring of a projected image from the optical module onto a screen.

[0003] Here, the adjustment device for the optical module of Patent Document 1 will be described with reference to FIG. 12. FIG. 12 is a diagram schematically showing the configuration of an adjustment device 101 for an optical module disclosed in Patent Document 1.

[0004] An optical module 105 under assembly including a liquid crystal panel 102 for displaying an image, a prism 103, and a projection lens 104 for projecting the image is installed in the adjustment device 101. Further, the liquid crystal panel 102 is connected to a control device 106. Further, the liquid crystal panel 102 is gripped by a robot 107 that adjusts the position and orientation of the liquid crystal panel 102.

[0005] The position and orientation of the liquid crystal panel 102 are adjusted as follows.

[0006] A test pattern is displayed on the liquid crystal panel 102 according to a command from the control device 106. The pattern displayed on the liquid crystal panel 102 is imaged and displayed on a transmissive screen 108 via the prism 103 and the projection lens 104. The test pattern displayed on the transmissive screen 108 is imaged by a camera 109, and the state of the test pattern is analyzed by the control device 106. Based on the analyzed result, the robot 107 is controlled to position the liquid crystal panel 102 at a predetermined orientation and position.

[0007] Finally, the bonding device 110 is controlled by the control device 106, and the liquid crystal panel 102 is fixed to the optical module 105, thereby allowing adjustment of the optical module 105. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 11-178014 [Overview of the Initiative]

[0009] A method for inspecting an optical module according to one aspect of this disclosure is: It comprises a display panel for displaying images and a projection lens for projecting the images from the display panel. A method for inspecting an optical module, A test pattern with at least three or more dot-shaped illuminated areas is displayed on the display panel. The process of displaying the pattern, The test pattern includes the light beams of each of the point-shaped lights projected from the projection lens. The process involves receiving a test pattern light with the light-receiving section of the wavefront sensor, The control unit calculates the phase distribution of the wavefront of the test pattern received by the wavefront sensor. Phase distribution calculation process, From the phase distribution of the wavefront, the region of each luminous beam of the point-shaped illuminated part of the test pattern is The phase distribution extraction process performed by the control unit, The parallelism of light in each region of the luminous beam of the point-shaped lighting unit cut out in the phase distribution cutting process. A parallelism calculation step in which the control unit calculates the parallelism, Two point-shaped illuminated units are located at positions symmetrical with respect to at least one of two orthogonal axes on the display panel, with the origin being the position where the optical axis of the projection lens passes through the display panel. Parallelism of light in each region of the luminous beam Compare them to each other A tilt determination step is performed in which the control unit determines whether or not the display panel is tilted relative to the projection lens. Execute sequentially. A method for inspecting an optical module according to another aspect of this disclosure is: A method for inspecting an optical module comprising a display panel for displaying an image and a projection lens for projecting the image from the display panel, A test pattern display step in which a test pattern having at least three or more dot-shaped illuminated areas is displayed on the display panel, A test pattern receiving step in which the test pattern, including the light beams of each of the point-shaped illuminated parts projected from the projection lens, is received by the light receiving section of the wavefront sensor, A phase distribution calculation step in which the control unit calculates the phase distribution of the wavefront of the test pattern received by the wavefront sensor, A phase distribution extraction step in which the control unit extracts the region of each luminous beam of the point-shaped illuminated portion of the test pattern from the phase distribution of the wavefront, A parallelism calculation step in which the control unit calculates the parallelism of light in each luminous beam region of the point-shaped lighting section cut out in the phase distribution cutting step, A tilt determination step is performed in which the control unit determines whether or not the display panel is tilted relative to the projection lens based on the parallelism of the light in each region of the aforementioned light beam, We will implement them sequentially, The number of dot-shaped illuminated areas in the test pattern of the display process is three, and the three dot-shaped illuminated areas are positioned at an equidistant distance from the position where the optical axis of the projection lens passes through the display panel. The tilt determination step involves the control unit determining that there is a tilt of the display panel relative to the projection lens when there is a difference in the parallelism of the light beams of the three point-shaped illuminated parts, which are located at positions equidistant from the position where the optical axis of the projection lens passes through the display panel.

Brief Description of the Drawings

[0010] [Figure 1] Diagram schematically showing the configuration of an optical module of a transmissive liquid crystal projector [Figure 2] Diagram schematically showing a simplified configuration of an optical module [Figure 3] Diagram schematically showing an adjustment device for an optical module according to an embodiment of the present disclosure [Figure 4] Flowchart for explaining an adjustment method for an optical module according to an embodiment of the present disclosure <​​​​​​​​​​​​​​​​​​​​​​​ [Modes for carrying out the invention]

[0011] In the optical module adjustment device disclosed in Patent Document 1, it is necessary to project the image of the test pattern onto the transmissive screen 108, which necessitates alignment of the optical module 105, the transmissive screen 108 which is the measurement unit, and the camera 109, resulting in a problem of long adjustment time. Furthermore, because it is necessary to detect even slight changes in the test pattern projected onto the transmissive screen 108 with the camera 109, there is a problem in that the position and orientation of the liquid crystal panel 102 cannot be accurately adjusted.

[0012] An object of one aspect of this disclosure is to provide an optical module adjustment method and inspection method that can adjust an optical module that projects light or images at high speed and with high precision.

[0013] The embodiments of this disclosure will be described below with reference to the drawings. Common components in each drawing are denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0014] A typical example of an optical module according to an embodiment of this disclosure will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the configuration of an optical module 1 of a transmissive liquid crystal projector.

[0015] The optical module 1 includes a light source 2, first and second dichroic mirrors 3a and 3b, first, second and third mirrors 4a, 4b and 4c, first, second and third display panels 5a, 5b and 5c, a prism 6, and a projection lens 7.

[0016] Light emitted from light source 2 is transmitted only in red light by the first dichroic mirror 3a, which is tilted with respect to the optical axis, and enters the first display panel 5a via the first mirror 4a. Light source 2 is a white light source such as a mercury lamp. Display panel 5 is a collective term for the first, second, and third display panels 5a, 5b, and 5c, and is specifically composed of the first, second, and third display panels 5a, 5b, and 5c. The first, second, and third display panels 5a, 5b, and 5c are, for example, transmissive liquid crystal panels. The first display panel 5a transmits light according to the image pattern and projects a red image onto a screen (not shown) via a prism 6 and projection lens 7.

[0017] Similarly, of the light emitted from the light source 2, the light reflected by the first dichroic mirror 3a is separated into green and blue light by the second dichroic mirror 3b, which is tilted with respect to the optical axis. The green light is reflected by the second dichroic mirror 3b and projects a green image onto the screen via the second display panel 5b, prism 6, and projection lens 7. The blue light passes through the second dichroic mirror 3b and projects a blue image onto the screen via the second and third mirrors 4b, 4c, third display panel 5c, prism 6, and projection lens 7.

[0018] In this way, the optical module 1 displays an image on the screen by superimposing three images: red, green, and blue.

[0019] During the assembly of the optical module 1, it is necessary to adjust the assembly so that the projected image on the screen at a predetermined position does not become blurred. This means adjusting the position and orientation of the first, second, and third display panels 5a, 5b, and 5c of the optical module 1 relative to the projection lens 7.

[0020] Figure 2 is a schematic diagram illustrating a simplified configuration of the optical module 1 according to an embodiment of this disclosure. Adjustment of the optical module 1 involves adjusting the position and orientation of the display panels 5, i.e., the first, second, and third display panels 5a, 5b, and 5c, with respect to the optical axis of the projection lens 7. Here, the direction of the optical axis of the projection lens 7 is z, the depth direction of the paper is x, the upward direction of the paper is y, the rotation direction around the x axis is α, and the rotation direction around the y axis is β. In the embodiment of this disclosure, the tilt α and β of the display panel 5 with respect to the optical axis, and the position z in the optical axis direction are adjusted. Hereafter, for the sake of simplicity, the explanation will be given using the optical module 1 shown in Figure 2.

[0021] The optical module 1 only needs to have a configuration that includes at least a display panel 5 and a projection lens 7; the configuration of other optical components is not restricted. Furthermore, while Figure 1 illustrates the configuration of the optical module 1 in a transmissive liquid crystal projector, any optical module that projects light or images is acceptable. For example, the display panel 5 could be a reflective panel such as a DMD (Digital Mirror Device), LCOS (Liquid crystal on silicon), a self-emissive panel such as an LED (light-emitting diode) panel, or an OLED (Organic light-emitting diode) panel. For instance, Figure 1 shows a three-panel configuration using three display panels 5, but a single-panel configuration using only one display panel 5 with a light source 2 that sequentially switches colors using a color wheel is also acceptable.

[0022] Furthermore, the projection lens 7 of the optical module 1 may constitute a part of the projection lens system of the product that incorporates the optical module 1. For example, the image projected from the projection lens 7 of the optical module 1 may be part of the optical module 1 of a product that further projects an image via another lens optical system.

[0023] Note that in Figure 2, the projection lens 7 is shown as a single lens for the sake of simplicity, but the projection lens 7 may be composed of multiple lenses or optical components.

[0024] Next, the configuration of the adjustment device for the optical module 1 according to the embodiment of this disclosure will be described with reference to Figure 3. Figure 3 is a schematic diagram showing the adjustment device 8 for the optical module 1 according to the embodiment of this disclosure.

[0025] The adjustment device 8 consists of a wavefront sensor 9 for measuring light projected from the optical module 1, a positioning mechanism 10 for adjusting the position and orientation of the display panel 5, an adhesive mechanism 11 for applying adhesive to fix the display panel 5 to the optical module 1, and a control unit 12 for controlling the wavefront sensor 9, the positioning mechanism 10, and the adhesive mechanism 11. The optical module 1 is under assembly, the projection lens 7 is fixed to the optical module 1, and the display panel 5 is held by the positioning mechanism 10. Here, the wavefront sensor 9 is a sensor that directly measures the phase distribution of the wavefront of light, and for example, a Shack-Hartmann sensor using a microlens array or a wavefront sensor utilizing shearing interference by a diffraction grating is used.

[0026] The wavefront sensor 9 is positioned so that light from the optical module 1 does not form an image, and the distance between the optical module 1 and the wavefront sensor 9 is sufficiently short compared to the distance at which light from the optical module 1 forms an image. This is because the optical module 1 is generally an optical system that magnifies and projects the image from the display panel 5, and in order to receive the test pattern of the display panel 5, which will be described later, all at once with the wavefront sensor 9, it is necessary to shorten the distance between the optical module 1 and the wavefront sensor 9. For this reason, compared to the conventional method of projecting light from the optical module 1 onto a screen, it is possible to make the adjustment device smaller.

[0027] Furthermore, no other optical components are placed between the optical module 1 and the wavefront sensor 9. This is because placing other optical components between the optical module 1 and the wavefront sensor 9 would reduce the measurement accuracy due to the influence of errors in the optical properties or alignment of these components. By not placing other optical components in this way, high-precision measurements can be achieved.

[0028] Next, the adjustment method for the optical module 1 according to the embodiment of this disclosure will be explained step by step using the flowchart in Figure 4. Figure 4 is a flowchart illustrating the adjustment method for the optical module 1 according to the embodiment of this disclosure.

[0029] In step S1, a test pattern is displayed on the display panel 5 by command from the control unit 12.

[0030] Figure 5 is a schematic diagram showing an example of a test pattern for the display panel 5. In Figure 5, the horizontal direction of the paper is the x-axis, the vertical direction is the y-axis, the inclination around the x-axis is α, and the inclination around the y-axis is β. Point O is the center of the adjustment axis of the adjustment device 8 and also the optical axis of the projection lens 7. The test pattern consists of four illuminated areas 13a, 13b, 13c, and 13d, which are the white areas in Figure 5, and an unlit area 14, which is the cross-hatched area in Figure 5. The illuminated areas 13a and 13b are positioned symmetrically with respect to the x-axis, and the illuminated areas 13c and 13d are positioned symmetrically with respect to the y-axis. In the embodiment of this disclosure, the illuminated areas 13a and 13b are positioned on the y-axis, and the illuminated areas 13c and 13d are positioned on the x-axis. Since each illuminated area 13a, 13b, 13c, and 13d is used as a point light source, it is preferable that only one pixel is illuminated. However, if the light intensity is insufficient, multiple pixels can be lit to display a dot pattern with a diameter of 50 μm or less. By creating such a pattern, it can be considered an ideal point light source, and the error in the wavefront of light during the measurement described later can be minimized, thus enabling highly accurate measurements.

[0031] Next, in step S2, the test pattern on the display panel 5 is received by the wavefront sensor 9.

[0032] Figure 6 schematically shows the state in which the test pattern from Figure 5 is projected onto the light-receiving section 15 of the wavefront sensor 9. The horizontal direction of the paper is the H axis and the vertical direction is the V axis, and here the H axis and V axis correspond to the x axis and y axis in Figure 5, respectively.

[0033] The light-receiving section 15 of the wavefront sensor 9 receives luminous beams 16a, 16b, 16c, and 16d, which correspond to the illuminated sections 13a, 13b, 13c, and 13d of the test pattern in Figure 5, respectively. Since the illuminated sections 13a, 13b, 13c, and 13d are point-like patterns, the luminous beams 16a, 16b, 16c, and 16d are luminous beams obtained by transmitting ideal spherical wave light from a point light source through the projection lens 7. Furthermore, since the distance between the optical module 1 and the wavefront sensor 9 is sufficiently short compared to the distance at which light from the optical module 1 forms an image, the luminous beams 16a, 16b, 16c, and 16d are received as luminous beams with some spread. In addition, since the optical module 1 is generally an optical system that magnifies and projects the image from the display panel 5, the luminous beams 16a, 16b, 16c, and 16d are incident at an oblique angle on the surface of the light-receiving section 15 of the wavefront sensor 9. In the embodiments of this disclosure, for example, the light beams 16a, 16b, 16c, and 16d are incident on the light-receiving section 15 of the wavefront sensor 9 at an angle of approximately 15 degrees with respect to the optical axis of the projection lens 7. As a result, the light beams 16a, 16b, 16c, and 16d each have an elliptical shape.

[0034] Furthermore, the size of the light-receiving section 15 of the wavefront sensor 9 must be such that it can simultaneously receive light beams 16a, 16b, 16c, and 16d. Figure 7 schematically shows the size relationship between the optical module 1 and the light-receiving section 15 of the wavefront sensor 9. When the field of view of the projected light from the optical module 1 is θ, the effective diameter of the projection lens 7 is D, and the distance between the optical module 1 and the wavefront sensor 9 is L, the size of the light-receiving section 15 of the wavefront sensor 9 is set to (2 × L × tanθ + D) or larger. By setting the size of the light-receiving section 15 of the wavefront sensor 9 in this way, all four light beams 16a, 16b, 16c, and 16d can be simultaneously received by a single wavefront sensor 9, which has the effect of enabling high-speed adjustment and inspection of the optical module 1. Furthermore, since measurements can be taken with only one wavefront sensor 9, the effects of machine-specific differences caused by using multiple wavefront sensors 9, or the effects of installation errors between the optical module 1 and the wavefront sensor 9 caused by adjusting the position of the wavefront sensor 9, can be eliminated, resulting in highly accurate adjustment and inspection of the optical module 1.

[0035] Next, in step S3, the control unit 12 calculates the phase distribution and light intensity distribution of the light wavefront detected by the light receiving unit 15 of the wavefront sensor 9. The calculation of the phase distribution and light intensity distribution of the light wavefront can be done using a known processing method for a Shack-Hartmann sensor or a wavefront sensor that utilizes shearing interference with a diffraction grating.

[0036] Next, in step S4, the control unit 12 extracts the regions of each luminous flux 16a, 16b, 16c, and 16d of the test pattern from the phase distribution of the wavefront of the light detected by the light receiving unit 15 obtained in step S3.

[0037] Since the positional relationship between the optical module 1 and the wavefront sensor 9 in the adjustment device 8 is predetermined for each region, it is sufficient to investigate and set the regions of each luminous beam 16a, 16b, 16c, and 16d in advance.

[0038] Next, in step S5, the control unit 12 calculates the parallelism of each luminous beam 16a, 16b, 16c, and 16d of the test pattern.

[0039] Parallelism is a value that represents the state of light diffusion or convergence, and in the embodiments of this disclosure, it can be expressed by equations (1) and (2) using diopters (unit: D) ​​that represent the refractive power of the lens. D_H=(4√3·C_Def+2√6·C_(+As3)) / R^2 (1) D_V=(4√3·C_Def−2√6·C_(+As3)) / R^2 (2) Here, D_H and D_V are the parallelism (in units of D) of the light-receiving section 15 of the wavefront sensor 9 shown in Figure 6 in the H-axis and V-axis directions, respectively. R is the radius of the light beam (in units of mm), and C_Def and C_(+As3) are the amount of defocus aberration (in units of μm) in the optical axis direction and the amount of astigmatism (in units of μm) in the HV direction, obtained by fitting the phase distribution of the wavefront of the light beam with the Zernike polynomial.

[0040] The C_Def and C_(+As3) for each luminous beam 16a, 16b, 16c, and 16d are calculated by the control unit 12 by fitting the phase distribution of the light wavefront in each region of each luminous beam 16a, 16b, 16c, and 16d, obtained in step S4, using the Zernike polynomial. The R for each luminous beam 16a, 16b, 16c, and 16d can be determined in advance by investigating and setting it, since the positional relationship between the optical module 1 and the wavefront sensor 9 in the adjustment device 8 is predetermined.

[0041] As described above, the parallelism of each luminous beam 16a, 16b, 16c, and 16d can be calculated by the control unit 12.

[0042] Next, in step S6, the control unit 12 determines whether the parallelism of the two luminous beams symmetrical to the adjustment axis of the adjustment device 8 is the same.

[0043] The control unit 12 determines whether the parallelism matches using a judgment threshold that has been pre-recorded in the control unit 12. If the difference in the parallelism of the two symmetrical light beams with respect to the adjustment axis of the adjustment device 8 is greater than or equal to the judgment threshold, the control unit 12 determines that the parallelism does not match and proceeds to step S7. Otherwise, the control unit 12 determines that the parallelism matches and proceeds to step S8. In the latter case, it means that the adjustment of the tilt of the display panel 5 with respect to the optical axis of the projection lens 7 is complete.

[0044] Therefore, in step S6, the control unit 12 checks whether or not the display panel 5 is tilted relative to the optical axis of the projection lens 7. Up to this step, it is an inspection method for the optical module 1, and including the subsequent steps, it becomes an adjustment method for the optical module 1.

[0045] In step S7, the tilt of the display panel 5 is adjusted by the positioning mechanism 10 so that the parallelism of the two symmetrical luminous beams matches the adjustment axis of the adjustment device 8.

[0046] As an example, a method for adjusting the tilt α of the display panel 5 around the x-axis using the positioning mechanism 10 will be described. When the display panel 5 is tilted only in the α direction, there is a difference between the distance from the light-up part 13a of the display panel 5 to the projection lens 7 and the distance from the light-up part 13b of the display panel 5 to the projection lens 7. Therefore, the position where the light-up part 13a is imaged by the projection lens 7 is different from the position where the light-up part 13b is imaged by the projection lens 7. This is equivalent to the difference in parallelism between the light beams 16a and 16b received by the wavefront sensor 9 in Figure 6. Conversely, when the tilt of the display panel 5 is adjusted to the optical axis of the projection lens 7, the position where the illuminated part 13a is imaged by the projection lens 7 and the position where the illuminated part 13b is imaged by the projection lens 7 coincide. Therefore, in order to adjust the tilt α of the display panel 5 and the optical axis of the projection lens 7, it is sufficient to match the parallelism between the light beams 16a and 16b received by the wavefront sensor 9 in Figure 6.

[0047] Similarly, to adjust the tilt β of the display panel 5 in Figure 5 around the y-axis, the parallelism between the light beam 16c and the light beam 16d received by the wavefront sensor 9 in Figure 6 should be matched.

[0048] The tilt adjustment of the display panel 5 is performed by the control unit 12, which calculates the amount of tilt adjustment from the parallelism of each luminous beam 16a, 16b, 16c, and 16d, and then issues a command to the positioning mechanism 10. The amount of tilt adjustment by the positioning mechanism 10 is determined, for example, based on a database that shows the relationship between the parallelism of each luminous beam and the amount of tilt adjustment, which has been investigated in advance.

[0049] After step S7 is completed, the process returns to step S2, and steps S2 through S6 are repeated. In step S6, steps S2 through S6 are repeated until the difference in parallelism between two symmetrical luminous beams with respect to the adjustment axis of the adjustment device 8 becomes smaller than the judgment threshold.

[0050] Next, in step S8, the positioning mechanism 10 adjusts the position of the display panel 5 in the optical axis direction so that the parallelism of each luminous beam of the test pattern matches the design value.

[0051] The image formation position of the image projected from optical module 1 is determined by design. Therefore, the parallelism of each light beam 16a, 16b, 16c, and 16d emitted from projection lens 7 can also be determined by design.

[0052] Since the tilt of the display panel 5 relative to the projection lens 7 has been adjusted up to step S6, in this step the positioning mechanism 10 adjusts the display panel 5 in the direction of the optical axis of the projection lens 7, that is, in the z-axis direction of the coordinate system in Figure 3, so that the parallelism of each light beam matches the design value. The amount of adjustment in the z-axis direction by the positioning mechanism 10 is determined by the control unit 12 based on, for example, a database that shows the relationship between the parallelism of each light beam and the amount of adjustment in the z-axis direction, which has been investigated in advance. Alternatively, steps S1 to S5 may be repeated, and the control unit 12 may adjust the z-axis direction of the display panel 5 while monitoring the parallelism of each light beam.

[0053] Finally, in step S9, the display panel 5 is fixed to the optical module 1 by the adhesive mechanism 11.

[0054] As described above, the inspection method for the optical module involves calculating the phase distribution of the wavefront of the test pattern projected from the optical module 1, extracting the region of each luminous beam from the point-like illuminated parts of the test pattern from the phase distribution, calculating the parallelism of the light in each extracted region of luminous beam, and determining whether or not there is a tilt of the display panel 5 relative to the projection lens 7 based on the parallelism of the light in each region of luminous beam. As a result, when performing the adjustment method thereafter, the orientation of the display panel 5 of the optical module 1 can be adjusted based on the determination result so that the parallelism of each luminous beam matches, eliminating the need to project the image of the test pattern onto a transmissive screen, and eliminating the need to detect slight changes in the test pattern projected onto the transmissive screen with a camera. Therefore, the optical module 1 that projects light or images can be adjusted at high speed and with high precision.

[0055] In the example of the test pattern on the display panel 5 in Figure 5, the four lighting units 13a, 13b, 13c, and 13d are shown to be lit simultaneously. However, the four lighting units 13a, 13b, 13c, and 13d can also be lit sequentially by dividing the time. In this case, the test pattern is displayed on the display panel 5 in step S1, and the test pattern on the display panel 5 is received by the wavefront sensor 9 in step S2. This process is repeated for each lighting unit and recorded in the control unit 12.

[0056] Although the flowchart in Figure 4 shows how to adjust the optical module 1 for a single display panel 5, for an optical module 1 equipped with multiple display panels 5 as shown in Figure 1, the flowchart in Figure 4 should be applied to each display panel 5. This is because the relationship between each display panel 5 and the projection lens 7 is the same as the relationship between the display panel 5 and the projection lens 7 shown in Figure 2.

[0057] In the flowchart of Figure 4, the adjustment method for the optical module 1 is described as including the steps of adjusting the tilt of the display panel 5 in step S7, adjusting the position of the display panel 5 in the optical axis direction in step S8, and fixing the display panel 5 to the optical module 1 in step S9. However, these steps are not necessary in the case of the inspection method for the optical module 1. It is sufficient to have the step of comparing the parallelism of the light beams in step S6. Thus, in the case of the inspection method for the optical module 1, if the comparison result or judgment result of comparing and judging the parallelism of the light beams in step S6 is obtained, it can be used to make adjustments, and the method of adjusting the optical module 1 can be effective.

[0058] In step S4, since the positional relationship between the optical module 1 and the wavefront sensor 9 in the adjustment device 8 is predetermined, an example was shown in which the regions of each luminous beam 16a, 16b, 16c, and 16d are investigated and set in advance. However, a method of automatically extracting each region may also be used. For example, the control unit 12 may extract the region of each luminous beam from the light intensity distribution obtained in step S3 and set each region.

[0059] Figure 8 schematically shows the relationship between the light intensity distribution 17 obtained in step S3 and each luminous flux 16a, 16b, 16c, and 16d. In the test pattern, the parts other than each luminous flux 16a, 16b, 16c, and 16d are off, so the light intensity distribution 17 will have intensity only in the regions of each luminous flux 16a, 16b, 16c, and 16d. Therefore, the parts that are above the intensity threshold pre-recorded in the control unit 12 are extracted as the regions of the luminous fluxes, and the regions of each luminous flux are set. By adopting this method, even if there is an installation error between the optical module 1 and the wavefront sensor 9, the regions of each luminous flux 16a, 16b, 16c, and 16d can be accurately set, which has the effect of achieving high-precision measurement.

[0060] Furthermore, in Figure 8, the region of each light beam may be set to be elliptical. This is because, as explained in step S2, the optical module 1 is generally an optical system that magnifies and projects the image of the display panel 5, so the light beams 16a, 16b, 16c, and 16d are incident at an oblique angle to the light-receiving section 15 of the wavefront sensor 9, and the light beams 16a, 16b, 16c, and 16d have an elliptical shape. For example, in the design where the light beams 16a, 16b, 16c, and 16d are incident on the light-receiving section 15 of the wavefront sensor 9 at an angle of approximately σ degrees with respect to the optical axis of the projection lens 7, the elliptical shape of the region of each light beam should be set with a ratio of the major axis to the minor axis of 1:cosσ. In the embodiment of this disclosure, since each light beam is incident on the light-receiving section 15 of the wavefront sensor 9 at an angle of approximately 15 degrees with respect to the optical axis of the projection lens 7, σ should be set to 15 degrees, and the ratio of the major axis to the minor axis of the ellipse should be set to 1:0.97.

[0061] Alternatively, the position of the luminous beam may be determined by pattern matching this elliptical shape to the intensity distribution 17. The detection position 18 in Figure 8 shows an example of detecting the luminous beam 16a using pattern matching. This method has the effect of accurately determining the position of the luminous beam compared to the method of extracting the portion above the intensity threshold as the luminous beam region, as described above.

[0062] Furthermore, in step S5, the parallelism is calculated by fitting the phase distribution of the wavefront of the luminous beam with the Zernike polynomial. However, the region of each luminous beam can also be set to be elliptical, and the parallelism can be calculated by fitting it with the elliptical Zernike polynomial. By adopting this method, the phase distribution of the wavefront of each elliptical luminous beam can be accurately fitted, resulting in a more accurate calculation of parallelism.

[0063] In step S1, the test pattern consists of four illuminated sections 13a, 13b, 13c, and 13d, as shown in Figure 5. Illuminated sections 13a and 13b are positioned symmetrically with respect to the x-axis, and illuminated sections 13c and 13d are positioned symmetrically with respect to the y-axis. However, it may also consist of three illuminated sections.

[0064] Figure 9 schematically shows an example where the test pattern of the display panel 5 consists of three illuminated sections. The test pattern consists of three illuminated sections 13e, 13f, and 13g and an unlit section 14. Furthermore, the distances of each of the three illuminated sections 13e, 13f, and 13g from point O, which is the center of the adjustment axis of the adjustment device 8 and the optical axis of the projection lens 7, are all equal. For example, the centers of the three illuminated sections 13e, 13f, and 13g can be positioned at the three vertices of an equilateral triangle.

[0065] Figure 10 schematically shows the state in which the test pattern from Figure 9 is projected onto the light-receiving section 15 of the wavefront sensor 9. The light-receiving section 15 of the wavefront sensor 9 receives the luminous fluxes 16e, 16f, and 16g, which correspond to the illuminated sections 13e, 13f, and 13g of the test pattern from Figure 9, respectively.

[0066] Figure 11 is a flowchart illustrating the adjustment method for optical module 1 using the test pattern in Figure 9. Each step from S21 to S29 corresponds to steps S1 to S9 in the flowchart of Figure 4, respectively. The steps that differ from the flowchart in Figure 4 are steps S26 and S27.

[0067] Next, in step S26, the control unit 12 determines whether the parallelism of the three light beams, which are at equal distances from the center of the adjustment axis of the adjustment device 8, is the same.

[0068] The control unit 12 determines whether the parallelisms match using a judgment threshold that has been pre-recorded in the control unit 12. If the difference in the parallelism of the three light beams is greater than or equal to the judgment threshold, it is determined that the parallelisms do not match, and the process proceeds to step S27. Otherwise, the control unit 12 determines that the parallelisms match, and the process proceeds to step S28. In this case, it means that the adjustment of the tilt of the display panel 5 with respect to the optical axis of the projection lens 7 is complete. Therefore, step S26 is a check for the presence or absence of tilt of the display panel 5 with respect to the optical axis of the projection lens 7.

[0069] In step S27, the tilt of the display panel 5 is adjusted by the positioning mechanism 10 under the control of the control unit 12 so that the parallelism of the three light beams, which are at equal distances from the center of the adjustment axis of the adjustment device 8, matches.

[0070] As described above, the control unit 12 can perform adjustments to the optical module 1 using a test pattern consisting of three illuminated sections 13e, 13f, and 13g. By adopting this method, the number of light beams received by the light-receiving section 15 of the wavefront sensor 9 can be reduced, which has the effect of making it easier to arrange the illuminated sections of the test pattern on the display panel 5 so that the regions of each light beam received by the light-receiving section 15 of the wavefront sensor 9 do not overlap.

[0071] The various aspects of this disclosure are described below.

[0072] [Aspect 1] A method for inspecting an optical module comprising a display panel for displaying an image and a projection lens for projecting the image from the display panel, A test pattern display step in which a test pattern having at least three or more dot-shaped illuminated areas is displayed on the display panel, A test pattern receiving step in which the test pattern, including the light beams of each of the point-shaped illuminated parts projected from the projection lens, is received by the light receiving section of the wavefront sensor, A phase distribution calculation step in which the control unit calculates the phase distribution of the wavefront of the test pattern received by the wavefront sensor, A phase distribution extraction step in which the control unit extracts the region of each luminous beam of the point-shaped illuminated portion of the test pattern from the phase distribution of the wavefront, A parallelism calculation step in which the control unit calculates the parallelism of light in each luminous beam region of the point-shaped lighting section cut out in the phase distribution cutting step, A tilt determination step is performed in which the control unit determines whether or not the display panel is tilted relative to the projection lens based on the parallelism of the light in each region of the aforementioned light beam, A sequential inspection method for optical modules.

[0073] [Aspect 2] The number of dot-shaped illuminated parts in the test pattern of the display process is four, and the dot-shaped illuminated parts are arranged symmetrically with respect to two orthogonal axes on the display panel, with the origin being the position where the optical axis of the projection lens passes through the display panel. The tilt determination step involves the control unit determining that there is a tilt of the display panel with respect to the projection lens when there is a difference in the parallelism of the light beams of the two point-shaped illuminated units, which are symmetrically positioned along each axis, with respect to two orthogonal axes on the display panel, where the origin is the position where the optical axis of the projection lens passes through the display panel. A method for inspecting an optical module as described in Embodiment 1.

[0074] [Aspect 3] The number of dot-shaped illuminated areas in the test pattern of the display process is three, and the three dot-shaped illuminated areas are positioned at an equidistant distance from the position where the optical axis of the projection lens passes through the display panel. The tilt determination step involves the control unit determining that there is a tilt of the display panel relative to the projection lens when there is a difference in the parallelism of the light beams of the three point-shaped illuminated parts, which are located at positions equidistant from the position where the optical axis of the projection lens passes through the display panel. A method for inspecting an optical module as described in Embodiment 1.

[0075] [Aspect 4] When the field of view of the light projected by the optical module is θ, the effective diameter of the projection lens is D, and the distance between the optical module and the wavefront sensor is L, the size of the light-receiving part of the wavefront sensor is (2 × L × tanθ + D) or greater. A method for inspecting an optical module as described in any one of embodiments 1 to 3.

[0076] [Aspect 5] In the parallelism calculation step, the parallelism is calculated by the control unit from the defocus aberration and the astigmatism. A method for inspecting an optical module as described in any one of embodiments 1 to 4.

[0077] [Aspect 6] The region of each luminous beam of the point-shaped lighting section in the phase distribution extraction process is made elliptical, and the parallelism is calculated by the control unit using the elliptic Zernike polynomial. A method for inspecting an optical module as described in any one of embodiments 1 to 5.

[0078] [Aspect 7] The inspection method for the optical module described in any one of the embodiments 1 to 6 is performed, If the control unit determines in the tilt determination step that the display panel is tilted, the system includes a tilt adjustment step in which the tilt of the display panel with respect to the projection lens is adjusted by a positioning mechanism that adjusts the tilt of the display panel under the control of the control unit, so that the parallelism of the light in each region of the point-shaped illuminated section is consistent. How to adjust the optical module.

[0079] [Aspect 8] The optical axis adjustment step is further performed after the tilt determination step, by adjusting the position of the display panel by the positioning mechanism under the control of the control unit, so that the parallelism of the light in each region of the point-shaped illuminated section matches the design value of the parallelism of the optical module, by moving the display panel in the optical axis direction of the projection lens. A method for adjusting the optical module described in Embodiment 7.

[0080] Furthermore, by appropriately combining any embodiment or modification from the various embodiments or modifications described above, the effects of each can be achieved. In addition, it is possible to combine embodiments with each other, or embodiments with each other, or embodiments with each other, as well as to combine features from different embodiments or embodiments.

[0081] According to this disclosure, the inspection method for the optical module involves calculating the phase distribution of the wavefront of the test pattern projected from the optical module, extracting the region of each luminous beam of the point-like illuminated part of the test pattern from the phase distribution, calculating the parallelism of the light in each extracted region of luminous beam, and determining whether or not the display panel is tilted relative to the projection lens based on the parallelism of the light in each region of luminous beam. As a result, when performing the adjustment method thereafter, the orientation of the display panel of the optical module can be adjusted based on the determination result so that the parallelism of each luminous beam matches, eliminating the need to project the image of the test pattern onto a transmissive screen and the need to detect slight changes in the test pattern projected onto the transmissive screen with a camera. Therefore, the optical module that projects light or images can be adjusted at high speed and with high precision. [Industrial applicability]

[0082] The methods for adjusting and inspecting optical modules according to the aforementioned aspects of this disclosure are useful for assembling and adjusting optical modules mounted in products that project light or images, such as liquid crystal projectors, head-mounted displays, smart glasses, or head-up displays. [Explanation of Symbols]

[0083] 1 Optical module 2 light source 3a First Dichroic Mirror 3b Second Dichroic Mirror 4a First Mirror 4b Second Mirror 4c 3rd Mirror 5 Display Panel 5a First display panel 5b Second display panel 5c Third display panel 6 prisms 7. Projection lens 8 Adjustment device 9 Wavefront Sensor 10 Positioning mechanism 11 Adhesion mechanism 12 Control Unit 13a Lighting section 13b Lighting section 13c Lighting part 13d Lighting part 13e Lighting part 13f Lighting section 13g Lighting part 14. Lights Off Section 15 Light receiving section 16a Luminous flux 16b Luminous flux 16c luminous flux 16d luminous flux 16e luminous flux 16f luminous flux 16g luminous flux 17 Intensity distribution 18 Detection location 101 Adjustment device 102 LCD panel 103 Prism 104 Projection Lens 105 Optical Module 106 Control device 107 Robots 108 Transparent Screen 109 Camera 110 Joining equipment

Claims

1. A method for inspecting an optical module comprising a display panel for displaying an image and a projection lens for projecting the image from the display panel, A test pattern display step in which a test pattern having at least three or more dot-shaped illuminated areas is displayed on the display panel, A test pattern receiving step in which the test pattern, including the light beams of each of the point-shaped illuminated parts projected from the projection lens, is received by the light receiving section of the wavefront sensor, A phase distribution calculation step in which the control unit calculates the phase distribution of the wavefront of the test pattern received by the wavefront sensor, A phase distribution extraction step in which the control unit extracts the region of each luminous beam of the point-shaped illuminated portion of the test pattern from the phase distribution of the wavefront, A parallelism calculation step in which the control unit calculates the parallelism of light in each luminous beam region of the point-shaped lighting section cut out in the phase distribution cutting step, A tilt determination step is performed by the control unit to determine whether or not the display panel is tilted relative to the projection lens by comparing the parallelism of the light beam regions of the two point-shaped illuminated parts, which are located symmetrically with respect to at least one of two orthogonal axes on the display panel, with the origin being the position where the optical axis of the projection lens passes through the display panel, A sequential inspection method for optical modules.

2. The number of dot-shaped illuminated areas in the test pattern of the display process is four, and the dot-shaped illuminated areas are arranged symmetrically with respect to two orthogonal axes on the display panel, with the origin being the position where the optical axis of the projection lens passes through the display panel. The tilt determination step involves the control unit determining that there is a tilt of the display panel with respect to the projection lens when there is a difference in the parallelism of the light beams of the two point-shaped illuminated units, which are symmetrically positioned along each axis, with respect to two orthogonal axes on the display panel, where the origin is the position where the optical axis of the projection lens passes through the display panel. A method for inspecting an optical module as described in claim 1.

3. A method for inspecting an optical module comprising a display panel for displaying an image and a projection lens for projecting the image from the display panel, A test pattern display step in which a test pattern having at least three or more dot-shaped illuminated areas is displayed on the display panel, A test pattern receiving step in which the test pattern, including the light beams of each of the point-shaped illuminated parts projected from the projection lens, is received by the light receiving section of the wavefront sensor, A phase distribution calculation step in which the control unit calculates the phase distribution of the wavefront of the test pattern received by the wavefront sensor, A phase distribution extraction step in which the control unit extracts the region of each luminous beam of the point-shaped illuminated portion of the test pattern from the phase distribution of the wavefront, A parallelism calculation step in which the control unit calculates the parallelism of light in each luminous beam region of the point-shaped lighting section cut out in the phase distribution cutting step, A tilt determination step is performed in which the control unit determines whether or not the display panel is tilted relative to the projection lens based on the parallelism of the light in each region of the aforementioned light beam, We will implement them sequentially, The number of dot-shaped illuminated areas in the test pattern of the display process is three, and the three dot-shaped illuminated areas are positioned at an equidistant distance from the position where the optical axis of the projection lens passes through the display panel. The tilt determination step involves the control unit determining that there is a tilt of the display panel relative to the projection lens when there is a difference in the parallelism of the light beams of the three point-shaped illuminated parts, which are located at positions equidistant from the position where the optical axis of the projection lens passes through the display panel. Method for inspecting optical modules.

4. When the field of view of the projected light from the optical module is θ, the effective diameter of the projection lens is D, and the distance between the optical module and the wavefront sensor is L, the size of the light-receiving part of the wavefront sensor is (2 × L × tanθ + D) or greater. The method for inspecting an optical module according to claim 2 or 3.

5. In the parallelism calculation step, the parallelism is calculated by the control unit from the defocus aberration and the astigmatism. A method for inspecting an optical module according to claim 2 or 3.

6. The region of each luminous beam of the point-shaped lighting unit in the phase distribution extraction process is made elliptical, and the parallelism is calculated by the control unit using the elliptic Zernike polynomial. A method for inspecting an optical module according to claim 2 or 3.

7. The method for inspecting an optical module according to any one of claims 1 to 3 is carried out. If the control unit determines in the tilt determination step that the display panel is tilted, the system includes a tilt adjustment step in which the tilt of the display panel with respect to the projection lens is adjusted by a positioning mechanism that adjusts the tilt of the display panel under the control of the control unit, so that the parallelism of the light in each region of the point-shaped illuminated section is consistent. How to adjust the optical module.

8. The optical axis adjustment step is further performed after the tilt determination step, by adjusting the position of the display panel by the positioning mechanism under the control of the control unit, so that the parallelism of the light in each region of the point-shaped illuminated section matches the design value of the parallelism of the optical module, by moving the display panel in the optical axis direction of the projection lens. A method for adjusting an optical module according to claim 7.

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