JP2010145922A - Image forming apparatus and head-up display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high luminance and high resolution in an image forming apparatus using a laser projector and a microlens array, or in a head-up display device using the apparatus. <P>SOLUTION: The image forming apparatus comprises: a laser projector 1 projecting a video formed of an arrangement of a plurality of pixels; a microlens array 3 having microlenses 31 arranged in a horizontal arrangement direction and a vertical arrangement direction and arranged in such a manner that at least one interval of adjoining microlenses 31 in the horizontal arrangement direction is different from others; and an optical system correcting element 2, which is disposed in the optical paths between the laser projector 1 and the microlens array 3 and which corrects and projects a laser beam in such a manner that the incident angle of the laser beam to be incident on each microlens 31 is fitted within the aperture angle of the corresponding microlens 31. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that projects an image formed by an array of a plurality of pixels using a laser projector, and various information such as instrument information to a driver such as an automobile using the image forming apparatus. The present invention relates to a provided head-up display device.

  2. Description of the Related Art Conventionally, in a moving body such as an automobile, a head-up display device that projects various information images such as instrument information formed by a liquid crystal display, map information in a navigation device, and the like on a front window and transmits the information to a driver is known. Are known. Patent Documents 1 to 3 disclose that various head-up display devices are used in a vehicle.

  Patent Document 1 includes a dimming screen disposed behind a transmissive dot matrix liquid crystal display panel capable of graphic display, and a backlight light source disposed behind the dimming screen. A head-up display device is disclosed that includes a display that reflects information display on a translucent reflector provided in front of the windshield. According to this head-up display device, the washout phenomenon of the display device in the head-up device for a vehicle that projects and displays the display image of the display device on a translucent reflector (combiner) disposed in the front view of the driver's seat. In addition, the durability of the backlight used to transmit and illuminate the display can be improved.

  Further, in Patent Document 2, a light emitting display source including a radiation mechanism that radiates display images such as various traveling data is arranged on the interior side of the roof panel located above the driver's seat, and a predetermined part of the instrument panel is arranged. Further, there is disclosed a vehicle head-up display provided with a mirror for projecting a display image radiated from a light emitting display source onto a front wind panel in front of a driver's seat. According to this vehicle head-up display, a large installation space is not required inside the vehicle instrument panel, and the layout becomes easy.

  And in patent document 3, in the vehicle head-up display which optically projects the information of a meter display source on a semi-transmissive reflective surface, the light transmission from the meter display source is provided between the meter display source and the semi-transmissive reflective surface. It is disclosed to provide a reflecting mirror that reflects a plurality of times. According to this disclosure, the reflection image of the display source visually recognized by the driver can be moved away from the vehicle by increasing the distance between the instrument display source and the transflective surface with the reflecting mirror.

  An embodiment of a head-up display device will be briefly introduced with reference to FIGS. FIG. 25 shows an embodiment in which various configurations of the head-up display device are incorporated in an instrument panel. Video information such as vehicle instrument information and map information from the navigation device is output and displayed on a liquid crystal display panel (LCD). A backlight as a light source is installed on the back surface of the LCD. By irradiating the LCD from the back surface, a concave mirror as an optical system enlarging element is irradiated with an image formed on the LCD. The image reflected and enlarged by the concave mirror is projected on the inside of the front window or a transmissive reflector provided on the front window. The operator can visually recognize a display image (virtual image) positioned forward from the front window. In addition, by setting the distance to the display image (distance L) as far as possible, the operator can check video information such as instrument information and map information with a small amount of movement of the focal position.

FIG. 26 is a view showing the state from behind the vehicle driver's seat, in which various types of video information are displayed within a display range surrounded by a broken line in the front window, and the driver is provided with various types of information arranged in the instrument panel. It is possible to obtain various information by video while paying attention to driving the vehicle without dropping the line of sight to the instruments.
JP 2000-131642 A Japanese Utility Model Publication No. 6-29095 Japanese Utility Model Publication No. 1-59740

  In such a head-up display device, as described in Patent Document 1 and FIG. 25, a liquid crystal display device is generally used as an image forming device. It has been adopted. In order to solve this power consumption problem, the present invention is premised on the use of a laser projector that uses laser light as a light source for an image forming apparatus. In this laser projector, a light source with relatively low power consumption such as a semiconductor laser can be used as the light source, and low power consumption of the entire head-up display device can be realized.

  Since this laser projector directly irradiates a laser beam having a small spot diameter, although the brightness is very high in the irradiation region, a spot region having a narrow irradiation range is formed. According to such a spot region formed by laser light, it is possible to realize a high-definition image with a very high resolution. However, due to the human visual characteristics that make it impossible to determine the difference in luminance above a certain luminance, the viewer will see the image as a low luminance image.

  In order to improve luminance, the present inventors have proposed to employ a microlens array in which a plurality of microlenses are arranged in an image forming apparatus using this laser projector. However, it has been confirmed that the pixels formed by laser scanning are not formed on evenly arranged microlenses. In such a case, the luminance improvement efficiency is lowered.

  The present invention is based on the above-described phenomenon, and by making the positional relationship between the microlens array and the pixels formed by the laser projector appropriate, an image forming apparatus that achieves high brightness and high resolution, and A head-up display device is proposed.

  For this reason, the image forming apparatus according to claim 1 uses a laser beam as a light source, a horizontal scanning unit that scans the laser beam in the horizontal scanning direction, and a vertical scanning unit that scans the laser beam in the vertical scanning direction. The laser projector that projects the image formed in the above and the microlens are arranged in the horizontal arrangement direction and the vertical arrangement direction, and the interval in the horizontal arrangement direction of the adjacent microlens is arranged so that it is different by at least one. An optical system that is disposed between the optical paths of the microlens array and the laser projector and the microlens array, and corrects and projects the incident angle of the laser light incident on each microlens within the aperture angle of the microlens. A correction element and an optical system enlarging element for enlarging an image formed on the radiation surface of the microlens array And it is characterized in and.

  Furthermore, the image forming apparatus according to claim 2 is arranged such that in the image forming apparatus according to claim 1, the horizontal interval between adjacent microlenses becomes narrower as the distance from the predetermined reference point increases. It is characterized by.

The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1, wherein the horizontal scanning direction of the laser projector and the horizontal arrangement direction of the microlenses are at a predetermined angle. It is arrange | positioned so that it may have.

  According to a fourth aspect of the present invention, there is provided a head-up display device comprising the image forming apparatus according to any one of the first to third aspects, wherein an image formed by the optical system enlarging element is projected onto a transmissive reflector. It is characterized by.

  According to the present invention, in an image forming apparatus using a laser projector, the positional relationship between the microlens and the pixel formed on the microlens array by the laser projector is made appropriate to achieve high brightness and high resolution. Is possible.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining the main configuration of a laser projector according to an embodiment of the present invention. The laser projector 1 used in this embodiment includes a control unit 11, laser light sources 12 for each color, a dichroic mirror group 13, a horizontal scanning mirror 14, and a vertical scanning mirror 15.

  The control unit 11 modulates and controls the laser light source 12 based on the input video signal, and controls the horizontal scanning mirror 14 and the vertical scanning mirror 15 to deflect the laser light from the laser light source 12 and image. The controller function is formed.

The laser light source 12 of this embodiment is provided for each of R, G, and B colors, and the output of the laser light is controlled by the control of the control unit 11. The outputted laser light is combined as one beam light by the dichroic mirror group 13. With the configuration of the present embodiment using such three primary colors, it is possible to generate full-color laser light. The laser light synthesized by the dichroic mirror group 13 is deflected by the horizontal scanning mirror 14 and the vertical scanning mirror 15 to form an image on the projection surface 7. For scanning by the horizontal mirror 14 and the vertical mirror 15, a complicated mechanism such as a galvanometer, a polygon mirror, a prism, an acoustooptic device, or the like may be used. However, miniaturization is achieved by using MEMS (micro electro mechanical system) technology. Integration is possible.

  Further, in the laser projector 1, by appropriately controlling the horizontal scanning mirror 14 and the vertical scanning mirror 15, it is possible to project an image in an appropriate shape as well as a rectangle such as an LCD. In a head-up display device, projection is performed on a non-planar projection surface such as a front window. Therefore, if a rectangular image is projected as it is, distortion may occur in the visually recognized image, but the shape and arrangement of the front window are considered. By projecting such a video, it becomes possible to visually recognize it as a video without distortion. Further, since the image shape can be deformed by controlling the horizontal / vertical scanning mirrors, it is possible to flexibly cope with the distortion caused by the shape of the front window, which differs depending on the vehicle type. Furthermore, by adopting a configuration that detects ambient light with various sensors and corrects the laser light output of the laser projector, it is possible to provide a brightness image suitable for ambient light and reduce power consumption. Become. In addition, the horizontal scanning mirror 14 and the vertical scanning mirror 15 are separated from each other using a uniaxial mirror in the drawing, but can be further reduced in size by forming a single unit using a biaxial mirror. .

The laser projector 1 according to the present embodiment is capable of generating a full-color image using R, G, B, and three colors, but is not limited thereto, and is configured with an appropriate number of laser light sources 12. It is good as well. When a single color image is projected by the single laser light source 12, the dichroic mirror 13 can be omitted as necessary. The above is the laser projector 1
Next, an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 2, the image forming apparatus includes a laser projector 1, a micro lens array 3 (MLA), a condenser lens 2 disposed between the optical paths of the laser projector 1 and the micro lens array 3, and a magnifying lens (or concave mirror). 4 is configured. The laser light output from the laser projector 1 is incident on the condenser lens 2. The condenser lens 2 performs correction so that the incident angle of the laser light incident on the microlens constituting the microlens array 3 falls within the aperture angle of the microlens. The microlens array 3 is configured by an array of a plurality of microlenses. Each microlens enters the laser beam corrected by the condenser lens 2 and forms an image on the back surface thereof. In the present invention, since the image is formed by the microlens array 3 in this way, it is possible to transmit light more effectively in the viewing direction than in the case of forming an image using a screen. An increase can be achieved. In addition, since sufficient luminance can be obtained even with a small amount of light, the output of the laser light source 12 can be suppressed to reduce power consumption.

  The image formed on the microlens array 3 is magnified by the magnifying lens (or concave mirror) 4 and projected onto the projection surface 7. In the case of a head-up display device, the projection surface 7 becomes a front window as a transmissive reflector. The image forming apparatus according to the present invention can be applied not only to a head-up display device but also to a projector device that directly forms an image on a projection surface or a rear projector device.

  As described above, the image forming apparatus according to the present embodiment includes the laser projector 1, the condenser lens 2, the microlens array 3, and the magnifying lens (or concave mirror) 4. Note that the condenser lens 2 and the magnifying lens (or concave mirror) 4 of the present embodiment correspond to the optical system correcting element and the optical system magnifying element as used in the present invention, respectively.

  Now, the microlens array 3 which is a component of the image forming apparatus will be described with reference to FIGS. FIG. 3 is a view showing an embodiment of a microlens array, in which a large number of microlenses 31 are arranged in a lattice pattern at a pitch interval d. The micro lens 31 is circular, and an edge 32 is formed between the micro lenses 31. FIG. 4 is an enlarged photograph of the actual microlens array 3, and it can be seen that the microlenses 31 are regularly arranged.

  FIG. 5 is a diagram illustrating a configuration of a microlens array 3 according to another embodiment, and the microlenses 31 are arranged in a hexagonal lattice shape. According to this arrangement, the area of the edge 32 can be suppressed and the microlenses 31 can be arranged densely. In the embodiment shown in FIGS. 3 to 5, the microlens is circular. However, the microlens is not limited to this shape, and can be appropriately formed. For example, the microlens 31 shown in FIG.

Next, the radiation characteristics of the microlens array 3 will be described using FIGS. 6 to 9 in comparison with the case where a screen is used. FIG. 6 is a schematic diagram when the screen 5 is used. An image irradiated from the laser projector 1 to the back surface of the screen 5 is visually recognized through a magnifying lens (or concave mirror) 4 that is focused on the screen 5. Although not shown in the schematic diagram, in the head-up display device, reflection by the front window is interposed between the magnifying lens (or concave mirror) 4 and the viewer. As the screen 5, a screen normally used for a rear projector in which a scatterer is diffused in a transparent material is used. The directivity characteristics on the radiation surface of the screen 5 are shown in FIG. This directional characteristic is drawn with the viewing direction set to 0 ° and the gain set to 1, and the directional characteristic is dull due to the property of the screen 5 in which an image is formed by reflecting light with a scatterer. When the screen 5 is used in this way, light is diffused in a direction other than the viewing direction, so that the gain in the viewing direction is low.

  In contrast, FIG. 7 shows a schematic diagram when the microlens array 3 is used for image formation. An image irradiated on the microlens array 3 from the laser projector 1 via the condenser lens 2 is visually recognized via a magnifying lens (or concave mirror) 4 that is focused on the microlens array 3. The directivity characteristics on the radiation surface of such a microlens 31 are shown in FIG. It can be clearly seen that the gain is steeply attenuated as it forms an angle with the viewing direction indicated by 0 °, that is, it has a sharp directivity. As described above, when the microlens array 5 is used, light can be effectively transmitted in the viewing direction, and an image with high luminance can be formed on the radiation surface of the microlens array 5.

  Next, an optical system correction element that is a component in the present invention will be described with reference to FIGS. FIG. 10 is a diagram showing a case where the optical system correction element is not used, and FIG. 11 is a diagram showing an embodiment of the present invention using the condenser lens 2 as the optical system correction element.

  Since the laser projector 1 functions as a point light source, a deflection angle α is generated by horizontal and vertical scanning. On the other hand, the microlens 31 has an opening angle β for efficiently emitting incident light. As shown in FIG. 10, when the microlens array 3 is directly irradiated, in the microlens 31 in the peripheral portion of the microlens array 3, the incident light from the laser projector 1 has an opening angle β due to the shake angle α. In other words, the incident laser beam cannot be efficiently emitted. For this reason, a decrease in luminance occurs in the peripheral portion of the macro lens array 3.

  In the present invention, in order to suppress a decrease in luminance when the laser projector 1 and the microlens array 3 are combined, an optical system correction element such as a condenser lens 2 is used between them as shown in FIG. It is a feature. The condenser lens 2 has a function of adjusting incident light to be parallel or substantially parallel, and includes one or more lenses. In the present embodiment, the laser light is corrected so as to be within the opening angle β of the microlens 31 positioned around the microlens array 3. As described above, by correcting the laser light incident on the microlens array 3 by the condenser lens 2, it is possible to generate an image with high brightness on the radiation surface of the microlens array 3.

  As described above, the image forming apparatus of the present invention includes a laser projector 1, a condenser lens 2 as an optical system correction element, a microlens array 3 (MLA), and a magnifying lens (or concave mirror) 4 as an optical system magnifying element. In order to achieve higher brightness and lower power of the image to be formed.

  In the laser projector 1, the laser light output from the laser light source 12 is scanned in the horizontal direction and the vertical direction by the horizontal scanning mirror 14 and the vertical scanning mirror 15, respectively. The pixel formation by 15 control will be described with reference to FIGS. 12 is a diagram showing how the horizontal scanning mirror is controlled, FIG. 13 is a diagram showing how the vertical scanning mirror is controlled, and FIG. 14 is a diagram showing how pixels are formed by scanning. FIG. 15 shows a state of pixel formation on an ideal microlens array.

The horizontal scanning mirror control shown in FIG. 12 shows the relationship of the deflection angle θ1 of the horizontal scanning mirror 14 with respect to the time axis t. In this embodiment, the deflection angle θ1 repeats vibration with a sine waveform. In the horizontal scanning of the laser beam, an approximate straight line portion (a line indicated by a one-dot chain line in the figure) that can be regarded as a substantially straight line is used in this waveform. When an approximate straight line portion as shown in the figure is used, a period A described on the time axis is a horizontal scanning period. As described above, in the horizontal scanning period A in which the deflection angle θ1 of the horizontal scanning mirror 14 is linear with respect to time, the laser light source 12 is repeatedly blinked to form a horizontal scanning line composed of a plurality of pixels. As shown in the state of screen formation by scanning in FIG. 14, one horizontal scanning line is formed in the horizontal scanning period A.

  The vertical scanning mirror control shown in FIG. 13 shows the relationship of the deflection angle θ2 of the vertical scanning mirror 15 with respect to the time axis t. In this embodiment, the deflection angle θ2 repeats vibration by a sawtooth wave system. In the vertical scanning of the laser beam, an approximate straight line portion (a line indicated by a two-dot chain line in the figure) that can be regarded as a substantially straight line is used as in the horizontal scanning. When the approximate straight line portion as shown in the figure is used, the period B described on the time axis is the vertical scanning period. By repeating horizontal scanning within this vertical scanning period, horizontal scanning lines arranged in the vertical scanning direction are formed, and one screen image is formed. In the state of screen formation by scanning in FIG. 14, it can be seen that a plurality of horizontal scanning lines are formed in the vertical scanning period B to form a screen.

  FIG. 15 shows an ideal positional relationship between the pixels formed by the control of the horizontal scanning mirror 14 and the vertical scanning mirror 15 and the microlens array. The figure is an enlarged view of a part of the microlens array 3, and the reference line near the center indicates the center of the deflection angle of the horizontal scanning mirror 14. Adjacent microlenses 31 are arranged at a distance e in the horizontal scanning direction. As shown in the figure, it is ideal that the pixel (shown by a dark square) fits in each microlens 31 and that the pixel is located near the center of each microlens 31. . According to such a positional relationship, each microlens 31 and each pixel have a one-to-one relationship, and there is no fear of color mixing due to a plurality of pixels incident on the microlens 31. In addition, there is no risk of loss due to the formation of pixels at the edge 32 formed between the microlenses 31.

  However, in practice, the positional relationship between the microlens 31 and the pixel may not be ideal due to various factors. The displacement between the microlens 31 and the pixel in the horizontal scanning direction will be described with reference to FIGS. FIG. 16 is a schematic diagram showing how the pixel formation position shifts in the horizontal scanning direction, and shows the pixel formation position in the horizontal scanning direction on the microlens array 3 with respect to the time axis t. ing. In this embodiment, the reference point is the center of the deflection angle of the horizontal scanning mirror 14. As shown in the figure, in the ideal characteristic where the pixel formation position is linear with respect to the time axis, the vertical axis is obtained when the laser light source is turned on at equal intervals T as shown in t (a) to t (g). As shown by a to g, pixels are formed at equally spaced positions.

However, mainly due to the error due to the adoption of the approximate straight line described with reference to FIG. 12, the actual relationship between the time axis t and the pixel formation position in the horizontal scanning direction has characteristics as indicated by a curve in the figure. This figure is a schematic diagram exaggerating the actual characteristic curve in order to explain the deviation. According to this figure, the error from the ideal characteristic increases as the distance from the reference point increases. Specifically, on the time axis, a curve is formed above the ideal characteristic before the reference point and below the ideal characteristic after the reference point. In such actual characteristics, when the laser light source is turned on at equal intervals T as in t (a) to t (g), the vertical axis indicates a ′ to g ′ in the drawing. A pixel is formed at the position. As can be seen from the figure, the pixel formation position d ′ at the reference point coincides with the ideal pixel formation position d, but it can be seen that the deviation increases as the distance from the reference point increases. Specifically, in the actual characteristics as shown in the figure, the intervals A to C of the pixel formation positions are in a size relationship of A>B> C.

FIG. 17 is a diagram showing a state of pixel formation on the microlens array 3 when such a shift in the pixel formation position in the horizontal scanning direction occurs. The microlenses 31 are arranged at equal intervals e in the horizontal arrangement direction as shown in the figure. In the drawing, the pixels indicated by dark rectangles are within the microlens 31 near the reference line (the point where the reference line and one horizontal scanning line intersect with each other is the reference point in FIG. 16), but as the distance from the reference line increases. The shift in which the distance between the pixels is reduced is enlarged, gradually deviating from the center of the microlens 31, and a part of the pixel is applied to the edge 32. If this shift further increases, the pixel enters the adjacent microlens 31. When the pixel formation position shifts in the horizontal scanning direction as described above, loss of laser light due to the edge 32 and color mixture due to formation of a pixel in the adjacent microlens 31 occur. Therefore, it is impossible to improve luminance and resolution.

  The present embodiment is characterized in that the distance in the horizontal arrangement direction of the microlenses 31 is adjusted in order to solve such a problem. The embodiment will be described with reference to FIG. FIG. 18 is a diagram illustrating a state of pixels formed on the microlens array 3 as in FIG. 17. FIG. 17 is different from FIG. 17 in that the interval e in the horizontal arrangement direction of the adjacent microlenses 31 is adjusted. As shown in FIG. 16, when the distances A to C between the pixel formation positions become smaller as the distance from the reference point increases, the distance from the reference point becomes such that the distance between the microlenses 31 is e1> e2> e3> e4> e5> e6. By making the interval narrower, the center of the microlens 31 and the center of the pixel can be matched.

  The interval between the microlenses 31 is not limited to this embodiment, and can be appropriately selected in consideration of the actual shift amount as a relationship in which the arrangement becomes narrower as the distance from the reference point increases. For example, e1 = e2 = e3> e4 = e5 = e6, e1 to e3, e4 to e6, may be appropriately grouped to form a magnitude relationship. In such a case, there is a possibility that a pixel that is not formed at substantially the center of the microlens 31 may appear. However, by selecting the pixel so as to be accommodated in the microlens 31, luminance loss due to the edge portion 32 can be prevented.

  As described above, in the present embodiment, the microlens array is adjusted such that the interval in the horizontal arrangement direction of the microlenses 31 is adjusted, specifically, at least one of the intervals in the horizontal arrangement direction of the adjacent microlenses 31 is different. By adopting 3, it is possible to eliminate the deviation between the pixel and the microlens 31 generated in the horizontal scanning direction, and to improve the luminance and the resolution.

  Next, the displacement between the microlens 31 and the pixel due to vertical scanning will be described with reference to FIGS. FIG. 19 is a diagram for explaining the occurrence of displacement of the pixel formation position in the vertical scanning direction. As shown in the figure, horizontal scanning is repeated in one vertical scanning period B to form one image. Here, it is desirable that one horizontal scanning line be parallel to the horizontal scanning direction. However, when the vertical scanning mirror 15 continuously scans in the vertical scanning direction as in the present embodiment, it is shown in the figure. Thus, the horizontal scanning line is inclined. If this inclination becomes significant, the pixels cannot be accommodated in the microlens 31, and problems such as a decrease in luminance and a decrease in resolution occur.

FIG. 20 is a diagram showing an example where the horizontal scanning line is inclined. This figure also describes the pixel shift in the horizontal scanning direction described above. The horizontal scanning line is inclined with respect to the horizontal scanning direction, and the pixel located at the end does not fit in the microlens 31 but covers the edge 32. If this shift further increases, the pixel enters the adjacent microlens 31. If the horizontal scanning line is inclined as described above, the loss of laser light due to the edge 32 and color mixing due to the formation of pixels in the adjacent microlens 31 may occur, thereby improving the luminance. The resolution cannot be improved.

  In the present embodiment, the arrangement relationship between the laser projector 1 and the microlens array 3 is characterized in order to solve such a displacement between the microlens 31 and the pixels due to the inclination of the horizontal scanning line. Specifically, as shown in FIG. 21, the horizontal arrangement direction of the microlenses 31 is arranged to have a predetermined angle γ with respect to the horizontal scanning direction of the horizontal scanning mirror 14. By arranging in this way, pixels can be formed in each microlens 31. In the figure, the microlens array 3 is tilted. However, when this is done, the image formed is also tilted. Accordingly, the laser projector 1 is tilted with reference to the image to be formed, that is, the microlens array 3 as a reference, and pixels are formed in each microlens 31. By doing so, pixels are formed in each microlens 31 and the formed image is not inclined.

  As described above, in this embodiment, in addition to the positional deviation of the pixels in the horizontal scanning direction, the inclination of the horizontal scanning line is taken into consideration, and the horizontal scanning line generated by the continuous scanning by the horizontal scanning mirror 15 is considered. The deviation between the pixel and the microlens 31 due to the inclination of can be eliminated, and further increase in luminance and resolution can be realized.

  The laser projector 1 may correct the intensity of the laser light source 12 based on the intensity of ambient light. Such correction can be realized by inputting a signal from a sensor for detecting ambient light to the control unit 11 of the laser projector 1 described with reference to FIG. When the ambient light intensity is high, the intensity of the laser light source 12 is increased, and when the ambient light intensity is weak, the intensity is decreased to project an image having an intensity suitable for the ambient light, thereby providing an image with high visibility. In addition, it is possible to reduce power consumption. Further, not only the intensity of the ambient light but also the color tone of the ambient light may be detected to change the color tone of the laser light and provide a highly visible image. For example, in the evening or in the case of ambient light with strong redness such as in a tunnel, the visibility of the image can be improved by increasing the intensity of the green or blue laser light source 12.

  Then, the case where the image forming apparatus of this embodiment is mounted in a vehicle interior as a head-up display device will be described with reference to FIGS. 22 is a diagram for explaining inconveniences when the image forming apparatus described in FIG. 7 is mounted as a head-up display device in a vehicle interior, and FIG. 23 is a schematic diagram of an embodiment for solving the problem. FIG. 24 shows the state of the mounting. In the head-up display device, various methods are employed in order to increase the optical path length to the front window in a narrow room. As seen in Patent Document 2, it is often performed to increase the optical path length by installing the light emitting display source on the vehicle interior side of the roof panel and arranging the optical path in the visual field of the viewer. When the image forming apparatus according to the embodiment of the present invention is arranged in the vehicle interior as described above, the configuration of the condenser lens 2, the microlens array 3, and the like is as shown in FIG. It becomes the position which obstructs, and will cause the inconvenience on a visual field. Further, in the arrangement as shown in the figure, the display image itself is hindered.

In order to eliminate such inconveniences in the arrangement, in the present embodiment, a projection lens 6 as an optical system transmission element is disposed at the subsequent stage of the microlens array 3. Note that the projection lens 6 may be constituted by a single lens or a plurality of lens groups. As shown in FIG. 23, the projection lens 6 disposed at the rear stage of the microlens array 3 generates a projection image as a real image or a virtual image behind it. The magnifying lens (or concave mirror) 4 focuses on the projected image and provides the viewer with a magnified image by enlarging the projected image. According to this configuration, the distance a from the magnifying lens (or concave mirror) 4 to the microlens array 3 in FIG. 7 can be enlarged to the distance b from the magnifying lens (or concave mirror) 4 to the projection lens 6 in FIG. It becomes possible. By disposing each configuration so that the optical path of the enlarged distance b passes through the viewer's field of view, the image forming apparatus can be installed without hindering the viewer's field of view. Further, since the distance b can be adjusted not only by the focal length of the magnifying lens (or concave mirror) 4 but also by the selection of the projection lens 6, the degree of freedom in the layout of the image forming apparatus can be increased.

  FIG. 24 shows a diagram in the case where the image forming apparatus described in FIG. 23 is mounted in a vehicle interior. The laser projector 1, the condenser lens 2, the microlens array 3, and the projection lens 6 are attached near the ceiling inside the vehicle. In particular, by setting the mounting position in the vicinity of the front in the vehicle, it is possible to ensure an optical path in the vicinity of the front window where no object is normally placed, and the optical path of the image forming apparatus is not hindered. In addition, when installing these components, if necessary, and unitizing them after adjusting the optical path between the combined components in advance, it is not necessary to adjust the optical path between each component, and installation is easy. Become.

  On the other hand, the magnifying lens (in this case, a concave mirror) 4 is disposed on an instrument panel that houses various instruments or the like, or is disposed in an instrument panel provided with a window so as not to obstruct the optical path of the image forming apparatus. Is done. By using the projection lens 6 in this way, according to the present embodiment in which the distance to the magnifying lens (or the concave mirror 4) is extended, the projection lens 6 can be mounted in the vehicle interior without disturbing the visual field of the viewer. . Further, by selecting the projection lens 6, it is possible to adjust the distance to the magnifying lens (or concave mirror) 4, and the degree of freedom in mounting is improved.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention. Is.

The figure which showed the structure of the laser projector which concerns on embodiment of this invention. 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. The figure which showed the structure of the microlens array which concerns on embodiment of this invention. The enlarged photograph of the micro lens array which concerns on embodiment of this invention. The figure which showed the structure of the microlens array which concerns on other embodiment of this invention. The figure which showed the image forming apparatus at the time of using a screen. 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. The figure which showed the directional characteristic of the light in a screen radiation | emission surface. The figure which showed the directional characteristic of the light in a micro lens radiation | emission surface. The figure which showed the beam incident angle to a micro lens. The figure which showed the beam incident angle to a micro lens. The figure which showed the mode of horizontal scanning mirror control. The figure which showed the mode of the vertical scanning mirror control. The figure which showed the mode of screen formation by scanning. The figure which showed the mode of pixel formation on an ideal microlens array. The figure which showed the mode of the shift | offset | difference of the pixel formation position in a horizontal scanning direction. The figure which showed the shift | offset | difference of the pixel formation position on a micro lens array. The figure which showed the mode of the arrangement | sequence of the micro lens which concerns on embodiment of this invention. The figure which showed the mode of the shift | offset | difference of the pixel formation position by vertical scanning. The figure which showed the shift | offset | difference of the pixel formation position on a micro lens array. The figure which showed the mode of arrangement | positioning of the micro lens array which concerns on other embodiment of this invention. The figure explaining the inconvenience in mounting the image forming apparatus in the passenger compartment. FIG. 6 is a diagram illustrating an image forming apparatus according to another embodiment of the present invention. The figure which showed the mounting to the vehicle interior of the image forming apparatus which concerns on other embodiment of this invention. The figure which showed the conventional head-up display apparatus. The figure which showed the mode of the image display in the vehicle interior by a head-up display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser projector, 11 ... Control part, 12 ... Laser light source, 13 ... Dichroic mirror group, 14 ... Horizontal scanning mirror, 15 ... Vertical scanning mirror, 2 ... Condenser lens, 3 ... Micro lens array (MLA), 31 ... Micro Lens, 32 ... edge, 4 ... magnifying lens (or concave mirror), 5 ... screen, 6 ... projection lens, 7 ... projection surface

Claims (4)

A laser projector for projecting an image formed by an array of a plurality of pixels by using a laser beam as a light source, and a horizontal scanning unit that scans the laser beam in a horizontal scanning direction; and a vertical scanning unit that scans the laser beam in a vertical scanning direction;
A microlens array in which the microlenses are arranged in a horizontal arrangement direction and a vertical arrangement direction, and an interval between adjacent microlenses in the horizontal arrangement direction is different by at least one;
An optical system correction element that is disposed between the optical paths of the laser projector and the microlens array and corrects and projects the incident angle of the laser light incident on each microlens within the aperture angle of the microlens;
An image forming apparatus comprising: an optical system enlarging element that magnifies an image formed on a radiation surface of a microlens array. The image forming apparatus according to claim 1, wherein the horizontal intervals between adjacent microlenses are arranged so as to become narrower as they move away from a predetermined reference point. The image forming apparatus according to claim 1, wherein the horizontal scanning direction of the laser projector and the horizontal arrangement direction of the microlenses are arranged to have a predetermined angle. An image forming apparatus according to claim 1, comprising the image forming apparatus according to claim 1,
A head-up display device that projects an image from an optical expansion element onto a transmissive reflector.

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