WO2013175549A1

WO2013175549A1 - Light source unit and head-up display

Info

Publication number: WO2013175549A1
Application number: PCT/JP2012/062928
Authority: WO
Inventors: 祥夫棚橋
Original assignee: パイオニア株式会社
Priority date: 2012-05-21
Filing date: 2012-05-21
Publication date: 2013-11-28
Also published as: JPWO2013175549A1; JP5837685B2

Abstract

A light source unit is characterized by including a light source unit for emitting light; a stop means for narrowing the spot diameter of the light emitted from the light source; a first microlens array to which the light narrowed by the stop means is incident; and a second microlens array to which the light emitted from the first microlens array is incident. Thereby, the spot of the light emitted from the second microlens array may be reduced in size so that the resolution of an image may be suitably improved.

Description

Light source unit and head-up display

The present invention relates to a technical field using a microlens array.

Conventionally, a technique for applying a transmission screen using a microlens array to a head-up display or a laser projector has been proposed. For example, in Non-Patent Document 1, in a head-up display in which an intermediate image is generated on two microlens arrays by a laser projector, the front microlens array and the rear microlens array are separated by a focal length. A transmissive screen has been proposed in which the lens contours are aligned and face each other. In Patent Document 1, the front microlens array and the rear microlens array are arranged to face each other at least apart from the focal length of the microlens array, and the apex direction and the rear stage of the lens contour in the front microlens array are arranged. In this microlens array, a transmissive screen has been proposed in which the lens contour is shifted from the apex direction. In addition, Patent Document 2 describes a technique related to the present invention.

Japanese Patent No. 4769912 JP-A-10-170860

In the configuration described in Non-Patent Document 1 described above, it is necessary to strictly adjust the positions of the two microlens arrays, which tends to require time and effort for screen creation. On the other hand, in the configuration described in Patent Document 1, since it is not necessary to strictly adjust the positions of the two microlens arrays, a screen can be created easily and at low cost. However, in the configuration described in Patent Document 1, since light corresponding to one pixel overlaps with an adjacent pixel at the time of incidence on the subsequent microlens array, spots emitted from the subsequent microlens are adjacent to each other. There was a tendency to overlap. This is known as a cause of deterioration in resolution called crosstalk (see, for example, Patent Document 2).

Examples of the problem to be solved by the present invention include the above. An object of the present invention is to provide a light source unit and a head-up display capable of appropriately improving the resolution of an image in a configuration using a microlens array.

In the first aspect of the invention, the light source unit includes a light source that emits light, a diaphragm unit that narrows a spot diameter of the light emitted from the light source, and a first light that is narrowed by the diaphragm unit. A microlens array; and a second microlens array into which the light emitted from the first microlens array is incident.

According to a tenth aspect of the present invention, a head-up display includes the light source unit according to any one of the first to ninth aspects, and an image formed by the light source unit is visually recognized as a virtual image from the position of the user's eyes. It is characterized by making it.

The figure for demonstrating the problem of the optical element which concerns on a comparative example is shown. The figure for demonstrating the relationship between an incident spot diameter and exit pupil distribution is shown. The figure for demonstrating the reason it is difficult to narrow down an incident spot small is shown. The schematic block diagram of the optical element which concerns on a present Example is shown. The ray trace result by the optical element which concerns on a present Example is shown. An example of a simulation result when a microlens array having a sufficiently long focal length is used is shown. 1 shows a configuration of an image display device to which an optical element according to an embodiment is applied. The schematic block diagram of the optical element which concerns on the modification 1 is shown. The schematic block diagram of the optical element which concerns on the modification 2 is shown. The schematic block diagram of the microlens array which concerns on the modification 4 is shown.

In one aspect of the present invention, the light source unit includes a light source that emits light, a diaphragm unit that narrows a spot diameter of the light emitted from the light source, and a first micro that receives the light that is narrowed by the diaphragm unit. A lens array; and a second microlens array into which the light emitted from the first microlens array is incident.

The light source unit narrows down the spot diameter of the light emitted from the light source by the diaphragm means, causes the light narrowed down by the diaphragm means to enter the first microlens array, and causes the light emitted from the first microlens array to enter the first microlens array. 2. Enter the microlens array. Thereby, since the spot of the light emitted from the second microlens array can be reduced, it is possible to appropriately improve the resolution of the image.

In one aspect of the above light source unit, the diaphragm means narrows the spot diameter of the light emitted from the light source to the same size as the interval between the microlenses arranged in the first microlens array. Light is incident on the first microlens array. As a result, it is possible to appropriately reduce the influence of luminance unevenness and improve the image resolution.

In the above light source unit, a microlens array can be preferably used as the diaphragm means. Preferably, the distance between the microlenses arranged in the microlens array of the diaphragm means is configured to be approximately the same as the spot diameter of the light emitted from the light source.

In another aspect of the light source unit, the aperture means and the first microlens array are integrally configured as one optical element, and the aperture means is formed on one surface of the optical element, The first microlens array is formed on the other surface of the optical element. Accordingly, it is ensured that the spot diameter of the light incident on the first microlens array becomes a desired value, so that it is possible to save the trouble of assembly adjustment. In addition, the manufacturing cost can be reduced.

In another aspect of the light source unit, the first microlens array and the second microlens array are integrally configured as one optical element, and the first microlens array is formed on one surface of the optical element. A lens array is formed, and the second microlens array is formed on the other surface of the optical element. Thereby, manufacturing cost can be reduced.

In another aspect of the light source unit, the first microlens array and the second microlens array are separated from each other by a distance longer than the focal length of the microlenses arranged in the first microlens array. Yes. Thereby, the accuracy required when the first microlens array and the second microlens array are arranged to face each other can be reduced.

In the above light source unit, preferably, the interval between the microlenses arranged in the first microlens array is approximately the same as the interval between the microlenses arranged in the second microlens array.

In the above light source unit, preferably, the interval between the microlenses arranged in the first microlens array is smaller than the spot diameter of the light emitted from the light source.

The light source unit described above can be suitably applied to a head-up display that allows an image to be viewed as a virtual image from the position of the user's eyes.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Problems such as comparative examples]
First, before describing the contents of the present embodiment, problems of the configuration described in Patent Document 1 (hereinafter referred to as “comparative example”) will be described.

FIG. 1 is a diagram for explaining problems of the optical element 11x according to the comparative example. FIG. 1A and FIG. 1B are diagrams illustrating a schematic configuration of an optical element 11x according to a comparative example. FIG. 1A is a cross-sectional view of the optical element 11x taken along a plane perpendicular to the traveling direction of light emitted from a light source (not shown). In addition, a cross-sectional view showing an enlarged part of the optical element 11x is shown.

As shown in FIG. 1A, the optical element 11x according to the comparative example includes microlens arrays MLA1 and MLA2 in which a plurality of microlenses ML1 and ML2 are arranged. Light emitted from a light source (not shown) that emits light for displaying an image is incident on the microlens array MLA1, and light emitted from the microlens array MLA1 is incident on the microlens array MLA2. The The microlens arrays MLA1 and MLA2 function as so-called transmission screens.

Further, the microlens arrays MLA1 and MLA2 are arranged to face each other so that the surfaces on which the microlenses ML1 and ML2 are formed face each other. In this case, the microlens arrays MLA1 and MLA2 are arranged to face each other at a position separated by at least a distance longer than the focal length of the microlens ML1. Specifically, the microlens array MLA1 and the microlens array MLA2 are opposed to each other with a distance longer than twice the focal length of the microlens ML1.

FIG. 1B is a plan view of the microlens arrays MLA1 and MLA2. Specifically, a plan view showing an enlarged part of the microlens arrays MLA1 and MLA2 observed from the direction along the light traveling direction is shown. As shown in FIG. 1B, the microlenses ML1 and ML2 are configured with a regular hexagonal lens outline in a plan view. Further, the lens pitch P1 of the microlens ML1 arranged in the microlens array MLA1 and the lens pitch P2 of the microlens ML2 arranged in the microlens array MLA2 are approximately the same (P1≈P2). Furthermore, the microlens arrays MLA1 and MLA2 are arranged so that the regular hexagonal shapes that are the lens contours of the microlenses ML1 and ML2 are rotated by 30 degrees. That is, a regular hexagonal vertex direction that is the lens contour of the microlens ML1 arranged in the microlens array MLA1 and a regular hexagonal vertex direction that is the lens contour of the microlens ML2 arranged in the microlens array MLA2. The angle difference is 30 degrees. The vertex direction is defined by the direction from the center point (center of gravity) of the regular hexagon that is the lens contour toward each vertex of the regular hexagon (the same applies hereinafter).

The lens pitches P1 and P2 are, in other words, the distance between adjacent microlenses ML1 and ML2 arranged in the microlens array MLA1 and the microlens array MLA2, and the center of gravity of the adjacent microlenses ML1 and ML2 This corresponds to the interval (that is, the distance between the centers). Such a definition of the lens pitch shall be applied similarly in the following.

In the comparative example, the spot diameter SP1 of light emitted from the light source (corresponding to the spot diameter of light corresponding to one pixel) is larger than the lens pitch P1 of the microlens ML1 arranged in the microlens array MLA1 (SP1). > P1). That is, in the comparative example, light corresponding to one pixel is incident on the plurality of microlenses ML1.

Hereinafter, a spot of light corresponding to one pixel emitted from the light source is referred to as an “incident spot”, and the diameter of the incident spot is referred to as an “incident spot diameter”. The incident spot diameter is defined as the diameter of a circle in which the intensity of incident light is a predetermined value (for example, half the maximum value) (hereinafter the same).

FIG. 1C shows a ray tracing result by the optical element 11x according to the comparative example. In FIG. 1C, a plurality of microlenses ML1 and ML2 arranged in the microlens arrays MLA1 and MLA2 are shown in an overlapping manner. In addition, here, a ray tracing result for light corresponding to one pixel is shown. The ray tracing result is obtained by simulation or the like.

As shown in FIG. 1C, in the configuration according to the comparative example, the spot diameter SP2 of the light emitted from the microlens array MLA2 is the spot diameter SP1 of the light incident on the microlens array MLA1 (that is, the incident spot diameter). (SP2> SP1). This is because the microlens array MLA1 and the microlens array MLA2 are opposed to each other with a distance larger than twice the focal length of the MLA1. Hereinafter, the spot of light emitted from the microlens array MLA2 is referred to as an “eject spot”, and the diameter of the exit spot is referred to as an “eject spot diameter”.

As described above, in the configuration according to the comparative example, since light corresponding to one pixel overlaps with an adjacent pixel at the time of incidence on the subsequent microlens array MLA2, a spot emitted from the microlens array MLA2 (that is, an emission spot) Adjacent pixels overlap each other. For this reason, there is a tendency for crosstalk in which the resolution is degraded. Such crosstalk can be reduced by reducing the lens pitch P1 of the microlens array MLA1.

Next, the relationship between the incident spot diameter and the exit pupil distribution will be described with reference to FIG. Here, a microlens array MLA1 in which microlenses ML1 configured with regular hexagonal lens contours in a plan view are arranged in a grid is taken as an example.

FIG. 2A shows a case where an incident spot diameter SP11 that is about twice the lens pitch P1 of the microlens array MLA1 is used (SP11≈2 × P1). In FIG. 2A, the incident spot diameter SP11 is represented by a broken line, and the circumference indicated by the broken line represents a portion where the intensity of the incident light becomes a half value of the maximum value (the same applies to FIG. 2C). And). FIG. 2B shows the intensity distribution of the exit pupil when the incident spot diameter SP11 as shown in FIG. 2A is used. The intensity distribution of the exit pupil is a distribution formed on the surface of the microlens array MLA2 by the light from the microlens array MLA1 (the same applies to FIG. 2D). As shown in FIG. 2B, when the incident spot diameter SP11 is considerably larger than the lens pitch P1 of the microlens array MLA1, it can be seen that the arrangement of bright spots is sparse in the intensity distribution of the exit pupil. . In this case, the unevenness of the observed image tends to increase.

FIG. 2C shows a diagram in the case of using an incident spot diameter SP12 that is approximately the same as the lens pitch P1 of the microlens array MLA1 (SP12≈P1). FIG. 2 (d) shows the intensity distribution of the exit pupil when the incident spot diameter SP12 as shown in FIG. 2 (c) is used. As shown in FIG. 2D, when the incident spot diameter SP11 is approximately the same as the lens pitch P1 of the microlens array MLA1, it can be seen that the intensity distribution of the exit pupil is dense. In this case, an image with little unevenness is observed.

From the above, although the influence of crosstalk can be reduced by reducing the lens pitch P1 of the microlens array MLA1, if the incident spot diameter is considerably larger than the lens pitch P1 of the microlens array MLA1, It can be said that the brightness unevenness of the exit pupil increases. On the other hand, if the incident spot diameter is approximately the same as the lens pitch P1 of the microlens array MLA1, it can be said that the luminance unevenness is small. Therefore, if the lens pitch P1 of the microlens array MLA1 is reduced and the incident spot diameter is narrowed to the same extent as the lens pitch P1, it is considered that the influence of luminance unevenness can be reduced and the resolution can be increased. .

However, in an apparatus (for example, a laser projector) that scans light emitted from a light source with a MEMS mirror and displays an image, it is difficult to narrow the incident spot. The reason will be specifically described with reference to FIG.

FIG. 3 illustrates a configuration in which the light emitted from the light source is scanned on the microlens array MLA1 (screen) by the MEMS mirror 10. FIG. 3A shows a case where the MEMS mirror 10 and the microlens array MLA1 are separated from each other. In FIG. 3A, reference symbol SP51 indicates an incident spot at the center of the image, and reference symbols SP52 and SP53 indicate incident spots at the periphery of the image. The spot incident on the microlens array MLA1 is determined by the NA (numerical aperture) of the collimator lens 93 disposed between the light source and the MEMS mirror 10. When the MEMS mirror 10 and the microlens array MLA1 are separated from each other, the NA of the collimator lens 93 has to be lowered, and it can be seen that it is difficult to narrow the incident spot.

FIG. 3B shows a case where the MEMS mirror 10 and the microlens array MLA1 are close to a certain extent. In FIG. 3B, the symbol SP61 indicates the incident spot at the center of the image, and the symbols SP62 and SP63 indicate the incident spot at the periphery of the image. As shown in FIG. 3B, the incident spot can be narrowed at the center of the image, but the incident spot cannot be narrowed around the image. This is because when the MEMS mirror 10 is brought close to the microlens array MLA1, it is necessary to increase the scan angle in order to generate an intermediate image of the same size, and a lens is formed on a planar substrate having a realistic shape. In the microlens array MLA1, defocusing due to a large difference in distance from the MEMS mirror 10 between the image central portion and the image peripheral portion and spot elongation due to an increase in the incident angle at the image peripheral portion occur. It is.

From the above, it can be said that it is difficult to narrow the incident spot small in an apparatus that displays an image by scanning light with the MEMS mirror 10. Even if the MEMS mirror 10 and the microlens array MLA1 are separated from each other, it is possible to increase the NA by using the collimator lens 93 having a large aperture. Will be kicked. Further, when the MEMS mirror 10 is brought close to the microlens array MLA1 in order to increase the NA, the phenomenon shown in FIG. 3B occurs.

[Configuration of this embodiment]
In the present embodiment, in response to the contents described above, the light further narrowed down the spot diameter of the light emitted from the light source is made incident on the microlens array MLA1. Specifically, in this embodiment, a microlens array different from the microlens arrays MLA1 and MLA2 is arranged on the light incident side with respect to the microlens array MLA1, and the light from the light source is emitted by such a microlens array. Is made incident on the microlens array MLA1. In this case, light whose aperture spot diameter is narrowed down to the same size as the lens pitch P1 of the microlens array MLA1 is incident on the microlens array MLA1.

FIG. 4 is a diagram illustrating a schematic configuration of the optical element 11 according to the present embodiment. FIG. 4A shows a cross-sectional view of the optical element 11 taken along a plane perpendicular to the traveling direction of light emitted from a light source (not shown). Further, a cross-sectional view showing a part of the optical element 11 in an enlarged manner is shown. FIG. 4B is a plan view of the microlens arrays MLA1, MLA2, and ML3 included in the optical element 11. Specifically, a plan view is shown in which a part of the microlens arrays MLA1, MLA2, and ML3 is enlarged and observed from the direction along the light traveling direction.

As shown in FIGS. 4A and 4B, unlike the optical element 11x according to the comparative example, the optical element 11 according to the present example is a microlens disposed on the light incident side with respect to the microlens array MLA1. It further has an array MLA3. Light emitted from a light source (not shown) that emits light for displaying an image is incident on the microlens array MLA3, and light emitted from the microlens array MLA3 is incident on the microlens array MLA1. The light emitted from the microlens array MLA1 is incident on the microlens array MLA2.

The microlens array MLA3 is an example of the “aperture means” in the present invention, the microlens array MLA1 is an example of the “first microlens array” in the present invention, and the microlens array MLA2 is the “second microlens” in the present invention. An example of an “array”. In addition, a component that includes at least a light source (not shown) and the microlens arrays MLA1 to MLA3 corresponds to an example of a “light source unit” according to the present invention.

The microlens array MLA3 is configured as a plano-convex lens array, and a plurality of microlenses ML3 are formed on a surface on which light from a light source is incident. The microlens array MLA3 is configured such that the lens pitch P3 of the microlens ML3 is approximately the same as the spot diameter SP1 (that is, the incident spot diameter) of light corresponding to one pixel emitted from the light source (P3≈SP1). ). Furthermore, the microlens ML3 is configured with a regular hexagonal lens contour in plan view.

The microlens array MLA1 is disposed so as to face the microlens array MLA3. For example, the microlens array MLA3 is disposed within the focal depth range of the microlens array MLA3. Light having a spot diameter SP3 that has been narrowed down by the microlens array MLA3 is incident on the microlens array MLA1. The spot diameter SP3 is about the same size as the lens pitch P1 of the microlens array MLA1 (SP3≈P1). That is, the microlens array MLA3 causes the light, which has been narrowed down to the spot diameter SP3 having the same size as the lens pitch P1, to enter the microlens array MLA1.

The microlens array MLA2 is disposed to face the microlens array MLA1, and is disposed at a position separated by at least a distance longer than the focal length of the microlens ML1. Specifically, the microlens array MLA1 and the microlens array MLA2 are opposed to each other with a distance longer than twice the focal length of the microlens ML1. Further, the lens pitch P1 of the microlens ML1 arranged in the microlens array MLA1 and the lens pitch P2 of the microlens ML2 arranged in the microlens array MLA2 are configured to be approximately the same (P1≈P2). ). Further, the microlenses ML1 and ML2 are configured with regular hexagonal lens contours in plan view. In addition, the microlens arrays MLA1 and MLA2 are arranged so that the regular hexagonal shapes that are the lens contours of the microlenses ML1 and ML2 are rotated by 30 degrees relative to each other.

FIG. 5 shows a ray tracing result by the optical element 11 according to the present embodiment. In FIG. 5, for convenience of explanation, only the microlens arrays MLA1 and MLA2 are illustrated (the microlens array MLA3 is not illustrated), and a plurality of microlenses ML1 and ML2 arranged in the microlens arrays MLA1 and MLA2 are illustrated. It is shown repeatedly. In addition, here, a ray tracing result for light corresponding to one pixel is shown. In addition, the spot diameter SP1 (that is, the incident spot diameter) of light corresponding to one pixel emitted from the light source is shown in the lower left of FIG. 5 for reference. The ray tracing result is obtained by simulation or the like.

As shown in FIG. 5, according to the configuration of the present embodiment, the spot diameter SP4 (that is, the emission spot diameter) of the light emitted from the microlens array MLA2 is approximately the same as the incident spot diameter SP1. I understand. That is, according to the configuration according to the present embodiment, the emission spot diameter SP4 can be reduced to the same size as the incident spot diameter SP1, which is the spot diameter of the light incident on the foremost microlens array MLA3. I understand. This is considered to be because the light that has been narrowed down to the spot diameter SP3 having the same size as the lens pitch P1 by the microlens array MLA3 is incident on the microlens array MLA1.

According to the present embodiment described above, since the exit spot diameter SP4 can be made substantially equal to the incident spot diameter SP1, the resolution of the image can be improved. In the present embodiment, since the same microlens arrays MLA1 and MLA2 as in the comparative example are used, it is not necessary to strictly adjust the positions of the microlens arrays MLA1 and MLA2. Therefore, according to the present embodiment, the resolution of the image can be improved without increasing the difficulty of position adjustment.

In the above description, it has been described that the incident spot diameter SP1 is narrowed to the same degree as the lens pitch P1 of the microlens array MLA1 by the microlens array MLA3. Although it is preferable to narrow the incident spot diameter SP1 to the same size as the lens pitch P1, the present embodiment as described above can be used without narrowing the incident spot diameter SP1 to the same size as the lens pitch P1. The effect is obtained. That is, even when the incident spot diameter SP1 is narrowed down to a size slightly larger than the lens pitch P1, or when the incident spot diameter SP1 is narrowed down to a size slightly smaller than the lens pitch P1, the effect of this embodiment can be obtained. It is done. For example, a size for narrowing the incident spot diameter SP1 by the microlens array MLA3 can be determined based on an allowable resolution or the like.

In the above description, it has been described that the lens pitch P3 of the microlens array MLA3 is approximately the same as the incident spot diameter SP1. The lens pitch P3 is preferably configured to be the same as the incident spot diameter SP1, but the lens pitch P3 may not be configured to be the same as the incident spot diameter SP1. The lens pitch P3 may be configured to be slightly longer than the incident spot diameter SP1, or the lens pitch P3 may be configured to be slightly shorter than the incident spot diameter SP1.

In the above description, it has been described that the lens pitch P1 of the microlens array MLA1 and the lens pitch P2 of the microlens array MLA2 are approximately the same. Although it is preferable to configure the lens pitch P1 and the lens pitch P2 to be the same, the lens pitch P1 and the lens pitch P2 may not be configured to be completely the same. However, when the lens pitch P1 and the lens pitch P2 are configured to be the same, the microlens array MLA1 and the microlens array MLA2 can be manufactured using the same mold or the like. Can be manufactured.

[Preferred design example]
Next, a preferred design example of the above-described microlens array MLA3 will be described. As the microlens array MLA3, the focal length is sufficiently long so that the spot diameter SP3 (see FIG. 4 and the like) formed by the light incident on the microlens array MLA1 does not vary greatly depending on the scan angle of the MEMS mirror 10. It is preferable to use a lens having a deep microlens ML3. That is, a microlens having a sufficiently long focal length and a deep focal depth so that the spot size (spot size determined by wave optics) by light incident on the microlens array MLA1 is approximately the same at the image center and the image periphery. It is preferable to use an array MLA3.

FIG. 6 shows an example of a simulation result when the microlens array MLA3 having a sufficiently long focal length and a deep focal depth is used. Here, the interval between the MEMS mirror 10 and the microlens array MLA3 is “100 (mm)”, the interval between the microlens array MLA3 and the microlens array MLA1 is “21 (mm)”, and the focal length is “19. An example is shown in which a microlens array MLA3 having a central thickness of “1 (mm)” and a lens pitch P3 of “100 (μm)” is used. It is assumed that the incident spot diameter SP1 is about “100 (μm)”.

6 (a) to 6 (d) each show a top view of a ray tracing result from the MEMS mirror 10 to the microlens array MLA2 on the upper side, and the light incident on the microlens array MLA1 on the lower side. The intensity distribution is shown. Specifically, FIG. 6A shows a diagram when the scan angle is 0 degrees, FIG. 6B shows a diagram when the scan angle is 2 degrees, and FIG. 6C shows the scan. FIG. 6D shows a diagram when the angle is 8 degrees, and FIG. 6D shows a diagram when the scan angle is 14 degrees. In addition, the arrows presented in the lower graphs in FIGS. 6A to 6D represent the lens pitch P1 of the microlens array MLA1. For example, the lens pitch P1 is about “40 (μm)”.

6A to 6D, spots of approximately the same size are formed on the microlens array MLA1 at the center of the image and the periphery of the image, and the half width is approximately the same as the lens pitch P1 of the microlens array MLA1. It turns out that it is. Therefore, it can be said that it is preferable to use the microlens array MLA3 having the characteristics illustrated in FIG.

[Preferred application example]
Next, a preferred application example of the optical element 11 according to this embodiment will be described with reference to FIG.

FIG. 7 shows a configuration of the image display device 1 to which the optical element 11 according to the present embodiment is applied. As shown in FIG. 7, the image display device 1 includes an image signal input unit 2, a video ASIC 3, a frame memory 4, a ROM 5, a RAM 6, a laser driver ASIC 7, a MEMS control unit 8, and a laser light source unit 9. A MEMS mirror 10 and an optical element 11.

The image display device 1 is applied to, for example, a head-up display. The head-up display is a device that visually recognizes an image as a virtual image from the position of the eyes of a user (for example, a vehicle driver).

The image signal input unit 2 receives an image signal input from the outside and outputs it to the video ASIC 3.

The video ASIC 3 is a block that controls the laser driver ASIC 7 and the MEMS control unit 8 based on the image signal input from the image signal input unit 2 and the scanning position information Sc input from the MEMS mirror 10, and is ASIC (Application Specific Integrated). Circuit). The video ASIC 3 includes a synchronization / image separation unit 31, a bit data conversion unit 32, a light emission pattern conversion unit 33, and a timing controller 34.

The synchronization / image separation unit 31 separates the image data displayed on the screen as the image display unit and the synchronization signal from the image signal input from the image signal input unit 2 and writes the image data to the frame memory 4.

The bit data conversion unit 32 reads the image data written in the frame memory 4 and converts it into bit data.

The light emission pattern conversion unit 33 converts the bit data converted by the bit data conversion unit 32 into a signal representing the light emission pattern of each laser.

The timing controller 34 controls the operation timing of the synchronization / image separation unit 31 and the bit data conversion unit 32. The timing controller 34 also controls the operation timing of the MEMS control unit 8 described later.

In the frame memory 4, the image data separated by the synchronization / image separation unit 31 is written. The ROM 5 stores a control program and data for operating the video ASIC 3. Various data are sequentially read from and written into the RAM 6 as a work memory when the video ASIC 3 operates.

The laser driver ASIC 7 is a block that generates a signal for driving a laser diode provided in a laser light source unit 9 described later, and is configured as an ASIC. The laser driver ASIC 7 includes a red laser driving circuit 71, a blue laser driving circuit 72, and a green laser driving circuit 73.

The red laser driving circuit 71 drives the red laser LD1 based on the signal output from the light emission pattern conversion unit 33. The blue laser drive circuit 72 drives the blue laser LD2 based on the signal output from the light emission pattern conversion unit 33. The green laser drive circuit 73 drives the green laser LD3 based on the signal output from the light emission pattern conversion unit 33.

The MEMS control unit 8 controls the MEMS mirror 10 based on a signal output from the timing controller 34. The MEMS control unit 8 includes a servo circuit 81 and a driver circuit 82.

The servo circuit 81 controls the operation of the MEMS mirror 10 based on a signal from the timing controller.

The driver circuit 82 amplifies the control signal of the MEMS mirror 10 output from the servo circuit 81 to a predetermined level and outputs the amplified signal.

The laser light source unit 9 emits laser light to the MEMS mirror 10 based on the drive signal output from the laser driver ASIC 7.

The MEMS mirror 10 as a scanning unit reflects the laser beam emitted from the laser light source unit 9 toward the optical element 11. In this way, the MEMS mirror 10 forms an image to be displayed on the optical element 11. Further, the MEMS mirror 10 moves so as to scan on the optical element 11 under the control of the MEMS control unit 8 in order to display the image input to the image signal input unit 2, and the scanning position information at that time (For example, information such as a mirror angle) is output to the video ASIC 3.

The optical element 11 receives the laser light emitted from the MEMS mirror 10 and emits the laser light through the microlens arrays MLA3, MLA1, and MLA3 as described above. The image display device 1 displays an image corresponding to the light emitted from the optical element 11 such as the light reflected by the reflecting mirror (not shown) or the light enlarged by the magnifying element (not shown). It is made visible as a virtual image from the eye position (eye point).

Next, the detailed configuration of the laser light source unit 9 will be described. The laser light source unit 9 includes a case 91, a wavelength selective element 92, a collimator lens 93, a red laser LD1, a blue laser LD2, a green laser LD3, a monitor light receiving element (hereinafter simply referred to as “light receiving element”). 50).

The case 91 is formed in a substantially box shape with resin or the like. In order to attach the green laser LD3, the case 91 is provided with a hole penetrating into the case 91 and a CAN attachment portion 91a having a concave cross section, and a surface perpendicular to the CAN attachment portion 91a. A hole penetrating inward is formed, and a collimator mounting portion 91b having a concave cross section is formed.

The wavelength-selective element 92 as a synthesis element is configured by, for example, a trichromatic prism, and is provided with a reflective surface 92a and a reflective surface 92b. The reflection surface 92a transmits the laser light emitted from the red laser LD1 toward the collimator lens 93, and reflects the laser light emitted from the blue laser LD2 toward the collimator lens 93. The reflecting surface 92b transmits most of the laser light emitted from the red laser LD1 and the blue laser LD2 toward the collimator lens 93 and reflects a part thereof toward the light receiving element 50. The reflection surface 92 b reflects most of the laser light emitted from the green laser LD 3 toward the collimator lens 93 and transmits part of the laser light toward the light receiving element 50. In this way, the emitted light from each laser is superimposed and incident on the collimator lens 93 and the light receiving element 50. The wavelength selective element 92 is provided in the vicinity of the collimator mounting portion 91b in the case 91.

The collimator lens 93 emits the laser beam incident from the wavelength selective element 92 to the MEMS mirror 10 as parallel light. The collimator lens 93 is fixed to the collimator mounting portion 91b of the case 91 with a UV adhesive or the like. That is, the collimator lens 93 is provided after the synthesis element.

The red laser LD1 as a laser light source emits red laser light. The red laser LD1 is fixed at a position that is coaxial with the wavelength selective element 92 and the collimator lens 93 in the case 91 while the semiconductor laser light source is in the chip state or the chip is mounted on a submount or the like. ing.

Blue laser LD2 as a laser light source emits blue laser light. The blue laser LD2 is fixed at a position where the emitted laser light can be reflected toward the collimator lens 93 by the reflecting surface 92a while the semiconductor laser light source is in the chip state or the chip is mounted on the submount or the like. ing. The positions of the red laser LD1 and the blue laser LD2 may be switched.

The green laser LD3 as a laser light source is attached to the CAN package or attached to the frame package, and emits green laser light. The green laser LD 3 has a semiconductor laser light source chip B that generates green laser light in a CAN package, and is fixed to a CAN mounting portion 91 a of the case 91.

The light receiving element 50 receives a part of the laser light emitted from each laser light source. The light receiving element 50 is a photoelectric conversion element such as a photodetector, and supplies a detection signal Sd, which is an electrical signal corresponding to the amount of incident laser light, to the laser driver ASIC 7. Actually, at the time of power adjustment, one of red laser light, blue laser light, and green laser light is sequentially incident on the light receiving element 50, and the light receiving element 50 outputs a detection signal Sd corresponding to the amount of the laser light. To do. The laser driver ASIC 7 adjusts the power of the red laser LD1, the blue laser LD2, and the green laser LD3 according to the detection signal Sd.

For example, when the power of the red laser LD1 is adjusted, the laser driver ASIC 7 operates only the red laser driving circuit 71, supplies a driving current to the red laser LD1, and emits red laser light from the red laser LD1. A part of the red laser light is received by the light receiving element 50, and a detection signal Sd corresponding to the amount of light is fed back to the laser driver ASIC7. The laser driver ASIC 7 adjusts the drive current supplied from the red laser drive circuit 71 to the red laser LD1 so that the light amount indicated by the detection signal Sd is an appropriate light amount. In this way, power adjustment is performed. The power adjustment of the blue laser LD2 and the power adjustment of the green laser LD3 are similarly performed.

In addition, the above-described configuration unit including at least the laser light source unit 9 and the optical element 11 corresponds to an example of the “light source unit” according to the present invention.

[Modification]
Hereinafter, modifications of the above-described embodiment will be described. In addition, about the structure similar to the above-mentioned Example, the code | symbol same as the code | symbol shown in the Example is attached | subjected, and the description is abbreviate | omitted suitably. Further, a configuration that is not particularly described is the same as that of the embodiment.

(Modification 1)
FIG. 8 is a diagram illustrating a schematic configuration of the optical element 11a according to the first modification. FIG. 8 shows a cross-sectional view of the optical element 11a cut along a plane perpendicular to the traveling direction of light emitted from a light source (not shown). In addition, a cross-sectional view showing an enlarged part of the optical element 11a is shown.

As shown in FIG. 8, the optical element 11a according to the modification 1 is different from the optical element 11 according to the example in that it has a microlens array MLA3a instead of the microlens array MLA3. Specifically, in the microlens array MLA3 according to the embodiment, a plurality of microlenses ML3 are formed on a surface on which light is incident. However, in the microlens array MLA3a according to the first modification, the surface on which light is incident A plurality of microlenses ML3 are formed on the opposite surface. Such a microlens array MLA3a also functions in the same manner as the microlens array MLA3 according to the embodiment.

(Modification 2)
FIG. 9 is a diagram illustrating a schematic configuration of an optical element 11b according to Modification 2. FIG. 9 shows a cross-sectional view of the optical element 11b cut along a plane perpendicular to the traveling direction of light emitted from a light source (not shown). Further, a cross-sectional view showing an enlarged part of the optical element 11b is shown.

As shown in FIG. 9, the optical element 11b according to the modification 2 is different from the optical element 11 according to the embodiment in that it has one microlens array MLA4 instead of the microlens array MLA3 and the microlens array MLA1. . Specifically, the microlens array MLA4 according to the modified example 2 has a microlens ML3 similar to the microlens array MLA3 according to the embodiment formed on one surface, and the other surface according to the embodiment. A microlens ML1 similar to the microlens array MLA1 is formed. That is, in the modification 2, the microlens array MLA3 and the microlens array MLA1 according to the embodiment are integrally formed.

According to the microlens array MLA4 according to the second modified example, it is ensured that the spot diameter of the light incident on the microlens ML1 at the subsequent stage is a desired value, so that it is possible to save the labor of assembly adjustment. it can.

(Modification 3)
In the above-described embodiment, the microlens array MLA3 in which the microlens ML3 is formed only on one surface is shown, but the microlens array MLA3 in which the microlens ML3 is formed on both surfaces may be used. In the above-described embodiment, only one microlens array MLA3 is used, but a plurality of microlens arrays MLA3 may be used.

(Modification 4)
Modification 4 relates to another example of the configuration of the microlens array MLA1 and the microlens array MLA2.

FIG. 10 is a diagram showing a schematic configuration of microlens arrays MLA1 and MLA2 according to Modification 4. FIGS. 10A to 10D are cross-sectional views taken along a plane perpendicular to the traveling direction of light emitted from a light source (not shown). Moreover, sectional drawing which expanded and represented a part of component was shown.

FIG. 10A shows microlens arrays MLA1 and MLA2 according to a first example of the fourth modification. In this example, the microlens arrays MLA1 and MLA2 are arranged to face each other so that the surface of the microlens array MLA1 where the microlens ML1 is not formed faces the surface of the microlens array MLA2 where the microlens ML2 is formed. Yes.

FIG. 10B shows microlens arrays MLA1 and MLA2 according to a second example of the fourth modification. In this example, the microlens arrays MLA1 and MLA2 are arranged to face each other so that the surface of the microlens array MLA1 on which the microlens ML1 is formed and the surface of the microlens array MLA2 on which the microlens ML2 is not formed face each other. Yes.

FIG. 10C shows microlens arrays MLA1 and MLA2 according to a third example of the fourth modification. In this example, the microlens arrays MLA1 and MLA2 are arranged to face each other so that the surface of the microlens array MLA1 in which the microlens ML1 is not formed faces the surface of the microlens array MLA2 in which the microlens ML2 is not formed. ing.

FIG. 10D shows a microlens array MLA5 according to a fourth example of the fourth modification. In the microlens array MLA5 according to the fourth example, a microlens ML1 similar to the microlens array MLA1 is formed on one surface, and a microlens ML2 similar to the microlens array MLA2 is formed on the other surface. Has been. That is, in the microlens array MLA5, the microlens array MLA1 and the microlens array MLA2 described above are integrally formed. According to such a microlens array MLA5, it is only necessary to create one component on which the microlenses MLA1 and MLA2 are formed, so that the manufacturing cost can be further reduced.

(Modification 5)
In the above, an example in which the present invention is applied to a microlens array composed of microlenses having a regular hexagonal lens outline in plan view has been shown. However, the present invention is a microlens having variously shaped lens outlines. The present invention can be applied to a microlens array composed of lenses. For example, the present invention can be applied to a microlens array composed of microlenses having a lens contour such as a hexagonal shape (not a regular hexagonal shape), a rectangular shape, a square shape, or a circular shape.

(Modification 6)
Although the example which applies this invention to a head-up display was shown above, application of this invention is not limited to this. The present invention can be applied to laser projectors and head mounted displays in addition to head-up displays.

The present invention can be used for image display devices such as a head-up display, a head-mounted display, and a laser projector.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 10

MEMS mirror

11, 11a, 11b Optical element MLA1, MLA2, MLA3 Micro lens array ML1, ML2, ML3 Micro lens

Claims

A light source that emits light;
A diaphragm means for narrowing the spot diameter of the light emitted from the light source;
A first microlens array on which light narrowed down by the diaphragm means is incident;
A second microlens array on which light emitted from the first microlens array is incident;
A light source unit comprising:
The diaphragm means reduces the spot diameter of the light emitted from the light source to the same size as the interval between the microlenses arranged in the first microlens array. The light source unit according to claim 1, wherein the light source unit is incident on the light source unit.
3. The light source unit according to claim 1, wherein the aperture means is a microlens array.
4. The light source unit according to claim 3, wherein an interval between the microlenses arranged in the microlens array of the diaphragm unit is configured to be approximately equal to a spot diameter of light emitted from the light source. .
The aperture means and the first microlens array are integrally formed as one optical element, the aperture means is formed on one surface of the optical element, and the first surface is formed on the other surface of the optical element. The light source unit according to any one of claims 1 to 4, wherein a microlens array is formed.
The first microlens array and the second microlens array are integrally configured as one optical element, the first microlens array is formed on one surface of the optical element, and the other of the optical elements The light source unit according to claim 1, wherein the second microlens array is formed on the surface of the light source unit.
The first microlens array and the second microlens array are separated from each other by a distance longer than a focal length of microlenses arranged in the first microlens array. The light source unit according to any one of the above.
8. The interval between the microlenses arranged in the first microlens array and the interval between the microlenses arranged in the second microlens array are approximately the same. The light source unit according to any one of claims.
The light source unit according to claim 1, wherein an interval between the microlenses arranged in the first microlens array is smaller than a spot diameter of light emitted from the light source. .
A head-up display comprising the light source unit according to any one of claims 1 to 9, wherein an image formed by the light source unit is visually recognized as a virtual image from a position of a user's eyes.