JP2017077791A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device capable of displaying a plurality of virtual images of which longitudinal positions are different.SOLUTION: An intermediate image generation part 200 generates a first intermediate image 203 and a second intermediate image 204. An imaging lens 210 images the first intermediate image 203 on a first screen 230, and images the second intermediate image 204 on a second screen 240. A parallel flat plate prism 300 is arranged between the intermediate image generation part 200 and the imaging lens 210, and a light beam of the second intermediate image 200 passes through it. A first distance between the imaging lens 210 and the first screen 230 and a second distance between the image lens 210 and the second screen 240 are different.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a display device such as a head-up display device.

  A head-up display for an automobile projects an image from the dashboard side toward the shield glass of the front window, and displays various information as a virtual image in front of the driver's field of view. The product is in practical use. In a general head-up display, an intermediate image formed on a screen such as a diffuser (diffuser plate) is projected onto a front window glass (front glass) by a projection optical system (magnifying mirror or the like). Therefore, even when the position of the projection optical system is fixed, the position of the virtual image seen by the driver in the front-rear direction can be changed by changing the position of the screen on which the intermediate image is formed.

  The head-up display described in Patent Document 1 is configured such that intermediate images are displayed on the three display plates, the light from the backlight source reaches the upper display plate, and the emitted light enters the combiner. ing. Since the distance between the display board and the combiner is different, the three virtual images corresponding to the intermediate image of the display board appear to have different positions in the front-rear direction when viewed from the driver.

JP 2004-168230 A

  When displaying a plurality of virtual images at different positions, the distance to the combiner of the intermediate image corresponding to each virtual image must be changed. In order to change, three display panels are prepared for each intermediate image. Since a plurality of liquid crystal display devices must be prepared, there is a problem in that the cost is high and the position of the liquid crystal display device has to be arranged at an optimum position, so that assembly is complicated.

  This invention is made | formed in view of this situation, The objective is to provide the image display apparatus which can display the several virtual image from which a front-back position differs.

  An image display device according to the present invention includes an intermediate image generation unit that generates a first intermediate image and a second intermediate image, a first screen, a second screen, and the first intermediate image as the first intermediate image. An image forming lens that forms an image on one screen and forms the second intermediate image on the second screen, and is provided between the intermediate image generating unit and the image forming lens; A parallel plate prism through which light rays of the intermediate image pass, and a first distance between the imaging lens and the first screen, and between the imaging lens and the second screen. The second distance is different.

  According to this configuration, a plurality of intermediate images such as a first intermediate image and a second intermediate image are generated, and formed on the first screen and the second screen that are different from each other from the imaging lens. Thus, even when a virtual image having a different front-rear position is displayed for a viewer of the image, the virtual front-rear position of the second intermediate image can be adjusted by using a parallel plate prism. Therefore, it is not necessary to prepare separate display devices for a plurality of intermediate images, and cost increase can be reduced.

  Preferably, the intermediate image generation unit further includes a light source that irradiates parallel light to the intermediate image generation unit, and the intermediate image generation unit receives the first intermediate image and the second intermediate image from the intermediate image generation unit based on incident parallel light. The light beam that forms the intermediate image is emitted.

  According to this configuration, even when the intermediate generation unit is configured to display an image by transmitting light, the first intermediate image and the second intermediate image can be formed by the light source. By combining these configurations with the parallel plate prism, it is possible to provide a configuration that displays virtual images with different front and rear positions at a low cost for the viewer.

  Preferably, the parallel plate prism is disposed so as to cover the position of the second intermediate image in the intermediate image generation unit with respect to the imaging lens.

  According to this configuration, after the light beam of the second intermediate image is emitted, it can pass through the parallel plate prism. The virtual position of the intermediate image moves to the parallel plate prism side, and the imaging position by the imaging lens can be made far. Thereby, it is possible to provide a configuration that displays virtual images with different front and rear positions at a low cost for those who view the images.

  Preferably, in the parallel plate prism, the light incident surface and the light exit surface of the second intermediate image are both flat, and the light incident surface and the light exit surface are parallel to each other.

  According to this configuration, the light of the second intermediate image is maintained in the direction both before and after being incident on the parallel plate prism, and the second intermediate image is virtually degenerated by causing a detour due to refraction. Therefore, the image forming position by the image forming lens can be made far. Thereby, it is possible to provide a configuration that displays virtual images with different front and rear positions at a low cost for those who view the images.

  Preferably, the first screen is a diffusing plate that emits light of the first intermediate image emitted from the imaging lens as diffused light, and the second screen is from the imaging lens. It is a diffuser plate that emits the emitted light of the second intermediate image as diffused light.

  According to this configuration, by emitting the light emitted from the imaging lens as diffused light, a configuration for displaying a virtual image having a different front-rear position for a person viewing the image, including a plurality of images with different imaging positions. It can be provided at low cost.

  Preferably, the intermediate image generation unit generates the first intermediate image and the second intermediate image from the parallel light by modulating a spatial distribution of the component of the parallel light according to writing information.

  According to this configuration, since an intermediate image can be generated by modulating the spatial distribution, it is possible to provide an intermediate image that is a source of a virtual image having a different front-back position for a viewer of the image at a low cost.

  ADVANTAGE OF THE INVENTION According to this invention, the image display apparatus which can display the some virtual image from which a front-back position differs can be provided.

It is a figure explaining the structure of the image display apparatus which concerns on embodiment of this invention. It is a figure explaining the relationship between the refraction of light by the prism which concerns on embodiment of this invention, and an imaging position. It is a figure explaining the optical system which projects the virtual image which concerns on embodiment of this invention. It is a figure explaining the structure for the image display which concerns on embodiment of this invention.

  FIG. 1 is a diagram for explaining the configuration of an image display apparatus according to an embodiment of the present invention. The light source 100 is a parallel light source that emits parallel light or substantially parallel light, and includes a laser light source 110 and a collimator lens 120. The laser light source 110 emits light with enhanced spatial coherency through a special filter from an incoherent light source. The collimator lens 120 irradiates the parallel light from the light source 100 by converting the light from the laser light source 110 into parallel light by refraction. As a result, the light source 100 irradiates the intermediate image generating unit 200 with parallel light two-dimensionally.

  The intermediate image generation unit 200 receives the parallel light emitted from the light source 100. The intermediate image generation unit 200 emits light rays that form the first intermediate image 203 and the second intermediate image 204 based on the incident parallel light. The intermediate image generation unit 200 is a two-dimensional spatial light modulator (SLM) that converts incident two-dimensional incoherent light into two-dimensional coherent light, thereby converting optical information in parallel. A display device to display. The intermediate image generation unit 200 generates the first intermediate image 203 and the second intermediate image 204 from the parallel light by modulating the spatial distribution of the component of the parallel light according to the writing information.

  A spatial light modulator (SLM) is a two-dimensional array of microscopic elements called “light modulation elements”, and electrically distributes the spatial distribution of light from the light source 100, such as amplitude, phase, and polarization. By controlling to, light is changed (modulated). In other words, it is used to modulate amplitude modulation, phase modulation, or polarization spatially and temporally. Spatial light modulators include transmissive (LC) or reflective (LCOS) liquid crystal microdisplays, and in the present embodiment, the transmissive type is described. However, the same applies to reflective SLMs such as DMD and LCOS. Can be applied. Liquid crystals in the spatial light modulator are used on the basis of optical and electrical non-uniformities.

  An EL (Electro Luminescence) display may be used instead of the spatial light modulator. An EL display is a display that uses a substance that emits light when a voltage is applied, deposits a light emitter on a glass substrate, and controls the voltage applied to the substrate to perform display. In the case of EL, since the EL itself emits light, the light source 100 becomes unnecessary. If the spatial light modulator itself has a light emitting function, the light source 100 is not necessary in this case.

  The intermediate image generating unit 200 as a spatial light modulator modulates the distribution of the phase, polarization plane, amplitude, intensity, and propagation direction of the two-dimensional or one-dimensional readout light according to the writing information. The intermediate image generation unit 200 includes an address unit and a light modulation unit. The intermediate image generation unit 200 is a display device that can change the optical characteristics of the light modulation unit according to the writing information, modulate the reading light according to the change, and obtain output light reflecting the writing information. The intermediate image generation unit 200 is divided into an optical address type in which information is directly written by an optical system and an electric address type in which information is written by an electric signal, and is subdivided by materials of the address unit and the light modulation unit.

  The intermediate image generation unit 200 is divided into a first area and a second area, and displays the first intermediate image 203 in the first area and the intermediate image 204 in the second area. Although the upper half of the intermediate image generation unit 200 is shown as the first area and the lower half is shown as the second area, the division of the area is not necessarily performed in half, and the division ratio is set according to need. Magnitude. Since the virtual image based on the first intermediate image 203 is displayed in the foreground and the virtual image based on the second intermediate image 204 is displayed far away, the first region and the second region are displayed according to the position where more information is to be displayed. Set the split ratio.

  The imaging lens 210 is a projection lens that directly or indirectly receives the intermediate image generated by the intermediate image generation unit 200 and emits it as a projection image. The imaging lens 210 is a biconvex positive lens, and the light of the first intermediate image 203 and the second intermediate image 204 incident on the imaging lens 210 is enlarged and emitted. As a result, the imaging lens 210 forms the first intermediate image 203 on the first screen 230 and the second intermediate image 204 on the second screen 240.

  The first screen 230 is a surface on which the first intermediate image 203 is formed, and the second screen 240 is a surface on which the second intermediate image 204 is formed. It is comprised using the diffusion plate (diffuser) for reducing this. That is, the first screen 230 is a diffusion plate that emits the light beam of the first intermediate image 203 emitted from the imaging lens 210 as diffused light, and the second screen 240 is emitted from the imaging lens 210. Further, the diffusion plate emits the light beam of the second intermediate image 204 as diffused light.

  The second screen 240 is located farther from the reflecting surface 21 than the first screen 230 and is located closer to the projection optical system 400 than the first screen 230. That is, the first distance between the imaging lens 210 and the first screen 230 is different from the second distance between the imaging lens 210 and the second screen 240. The first distance is a distance from the position through which the first intermediate image 203 passes in the imaging lens 210 to the light of the first intermediate image 203 reaching the first screen 230, and the second distance is The distance from the position through which the second intermediate image 204 passes in the imaging lens 210 to the second intermediate image 204 reaches the second screen 240. Note that the start point may be common regardless of the light passing position, and may be, for example, each distance from the imaging lens 210 to the first screen 230 and the second screen 240. The end points may also be the center positions of the first screen 230 and the second screen 240. In any case, the first screen 230 and the second screen 240 are arranged so that the first distance and the second distance are different.

  The parallel plate prism 300 is provided between the intermediate image generating unit 200 and the imaging lens 210, and the light beam of the second intermediate image 204 passes therethrough. The parallel plate prism 300 is disposed so as to cover the position of the second intermediate image 204 in the intermediate image generation unit 200 with respect to the imaging lens 210. In the parallel plate prism 300, the incident surface and the exit surface of the light beam of the second intermediate image 204 are both flat, and the entrance surface and the exit surface are parallel. In the present embodiment, an example in which the parallel plate prism 300 is arranged on the incident side of the imaging lens 210 will be described, but the parallel plate prism 300 may be arranged on the emission side of the imaging lens 210.

  Although the original object position of the second intermediate image 204 is on the intermediate image generation unit 200, the apparent object position moves to the virtual position 305 by inserting the parallel plate prism 300. By moving the apparent object position to the virtual position 305, the distance from the virtual position 305 to the imaging lens 210 is shorter than that on the intermediate image generating unit 200, so that the magnification is increased and the imaging is performed. The position is also far away. The relationship between this prism and the imaging position will be described with reference to FIG.

  FIG. 2 is a diagram for explaining the relationship between the refraction of light by the prism according to the embodiment of the present invention and the imaging position. In FIG. 3, the parallel plate prism 300 inserted between the second intermediate image 204 and the imaging lens 210 is shown in an enlarged manner. The parallel plate prism 300 has a thickness t and a refractive index n of 1 or more. Light that forms an angle θ1 from the point O enters the parallel plate prism 300, passes through A and B, and is emitted from the parallel plate prism 300 at an angle θ1. Assuming that a line parallel to OA is O'B, the outgoing light OA from O apparently becomes outgoing light O'B from O '. The position O of the object on the intermediate image generating unit 200 apparently moves to O ′ on the virtual position 305. The shortening distance of the emission position is represented by OO ′ = Δz = t (1-1 / n).

  The intermediate image 204 in the second region, which is the lower half of the intermediate image generation unit 200, appears from the intermediate image generation unit 200 at a position closer to the imaging lens by Δz by the parallel plate prism 4. This position is a virtual position 305. Since the distance on the object side of the imaging lens 210 is shorter than when t = 0, the magnification is increased and the imaging position is also increased. Compared to when t = 0, when t ≠ 0, the magnification is increased and an image is formed at a position far from the imaging lens.

  The first screen 230 at the imaging position is closer to the projection optical system than the second screen 240, and the second intermediate image 204 projects a virtual image at a closer distance in front of the driver. Therefore, the projection distance of the virtual image can be set by appropriately setting the refractive index n and the thickness t of the parallel plate prism. If n and t of the parallel plate prism are respectively set with respect to the area on the other intermediate image generation unit 200, a virtual image is displayed at each appropriate projection distance.

  FIG. 3 is a diagram illustrating an optical system that projects a virtual image according to the embodiment of the present invention. The first intermediate image 203 imaged on the first screen 230 and the light of the second intermediate image 204 imaged on the second screen 240 are transmitted by the first screen 230 and the second screen 240. The light reaches the projection optical system 400 after being reflected or transmitted.

  The projection optical system 400 projects an image corresponding to the first intermediate image 203 and the second intermediate image 204 formed on the first screen 230 and the second screen 240. The projection optical system 400 is a concave reflection mirror, and the light of the first intermediate image 203 and the second intermediate image 204 is incident on a projection surface 410 such as a windshield. The projection plane 410 is a combiner, and projects virtual images 430 and 440 on the opposite side of the projection plane 410 when viewed from the driver. The intermediate image of the screen 230 at a position close to the projection optical system 400 becomes a virtual image 430 that appears at a position close to the driver, and the intermediate image of the screen 240 at a position far from the projection optical system 400 appears at a position far from the driver. A virtual image 440 is obtained.

  FIG. 4 is a diagram illustrating a configuration for image display according to the embodiment of the present invention. As described above, the first intermediate image 203 and the second intermediate image 204 are displayed on the intermediate image generation unit 200. The intermediate image generation unit 200 and the light source 100 that emits light to the intermediate image generation unit 200 are displayed on the display control circuit 500. Controlled by. The display control circuit 500 is a device that controls the overall operation of the display device, and includes, for example, a computer that executes processing by a processor such as a CPU based on a program stored in a storage unit. The display control circuit 500 controls the light intensity of each color by the modulation control of the intermediate image generation unit 200 so that the desired first intermediate image 203 and second intermediate image 204 are obtained in the intermediate image generation unit 200. The scanning of the light emitted from the light source 100 is controlled. An image for which display control is performed by the display control circuit 500 is input from the navigation device 510. For example, the vehicle speed is input to the display control circuit 500 so that the vehicle speed is displayed on the front side, and navigation information such as right and left turn instruction arrows is displayed on the back side.

  With the above-described configuration, a plurality of intermediate images such as the first intermediate image 203 and the second intermediate image 204 are generated, and the first screen 230 and the second screen are located at different positions from the imaging lens 210, respectively. By forming an image on the screen 240, the front and rear positions of the second intermediate image 204 can be adjusted by using the parallel plate prism 300 even when displaying a virtual image having different front and rear positions for the viewer. .

  That is, by arranging the parallel plane prism 300, the apparent object position moves in the light traveling direction, so that the image formation point can be shifted and a clear image can be displayed. Since each intermediate image generation unit 200 may be arranged at an equal distance from the imaging lens, adjustment of the intermediate image generation unit 200 is simple. In addition, it is not necessary to prepare separate display devices for a plurality of intermediate images, and cost increase can be reduced.

  In addition, it is complicated to adjust the arrangement of the optical system according to the position of the virtual image.When a plurality of display devices are used, the positional relationship of each display device is accurately determined in consideration of the balance of the entire optical system each time. Although there is a problem that it is difficult to adjust, in the present embodiment, the position of the intermediate image viewed from the imaging lens 210 apparently approaches Δz = t (1-1 / n) imaging lens, and imaging is performed. The magnification of the point (conjugate point) increases. Therefore, the projection distance of the virtual image can be set by appropriately setting the refractive index n and the thickness t of the parallel plate prism 300, and the virtual image can be displayed at each appropriate projection distance. At this time, the first screen 230 and the second screen 240 are installed at the image formation point (conjugate point). Compared to the thickness t = 0, the imaging magnification becomes larger when t ≠ 0, and therefore, a virtual image is projected at a distance closer than t = 0. By dividing one SLM region, an appropriate t, n parallel plate prism 300 can be installed in each region, and a virtual image can be projected at a different distance for each region.

  The present invention is not limited to the embodiment described above. That is, those skilled in the art may make various modifications, combinations, subcombinations, and alternatives regarding the components of the above-described embodiments within the technical scope of the present invention or an equivalent scope thereof. Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or changed within the scope of the purpose of the improvement or the idea of the present invention.

For example, in the above-described embodiment, the case where the parallel plate prism 300 is disposed only on the optical path corresponding to the second intermediate image 204 is illustrated. However, the first embodiment is within the range not exceeding the concept of the invention of claim 1. A parallel plate prism may also be disposed on the optical path corresponding to the intermediate image 203.
Moreover, in the above-described embodiment, the case where a virtual image that is visible in two places from the driver is displayed is illustrated, but by using three or more screens, virtual images are displayed at three or more positions in the perspective. Also good.

  As described above, the display device according to the present invention is useful for a head-up display device for a vehicle and is suitable for displaying different images at a plurality of display positions.

DESCRIPTION OF SYMBOLS 100 ... Light source 110 ... Laser light source 120 ... Collimator lens 200 ... Intermediate image production | generation part 203 ... 1st intermediate image 204 ... 2nd intermediate image 210 ... Imaging lens 230 ... 1st screen 240 ... 2nd screen 300 ... Parallel plate prism 305 ... Virtual position 400 ... Projection optical system 410 ... Projection plane 430, 440 ... Virtual image 500 ... Display control circuit 510 ... Navigation device

Claims (6)

An intermediate image generation unit for generating a first intermediate image and a second intermediate image;
A first screen;
A second screen;
An imaging lens for forming the first intermediate image on the first screen and forming the second intermediate image on the second screen;
A parallel plate prism provided between the intermediate image generation unit and the imaging lens, through which the light beam of the second intermediate image passes;
Have
A first distance between the imaging lens and the first screen is different from a second distance between the imaging lens and the second screen;
Image display device. A light source for irradiating the intermediate image generating unit with parallel light;
The intermediate image generation unit emits light rays that form the first intermediate image and the second intermediate image from the intermediate image generation unit based on incident parallel light.
The image display device according to claim 1. The parallel plate prism is disposed so as to cover the position of the second intermediate image of the intermediate image generation unit with respect to the imaging lens.
The image display device according to claim 1. The parallel plate prism is
Both the light incident surface and the light exit surface of the second intermediate image are flat surfaces,
The entrance surface and the exit surface are parallel;
The image display apparatus in any one of Claims 1-3. The first screen is a diffusing plate that emits the light beam of the first intermediate image emitted from the imaging lens as diffused light, and the second screen is emitted from the imaging lens. A diffusion plate that emits the light beam of the second intermediate image as diffused light;
The image display apparatus in any one of Claims 1-4. The intermediate image generation unit generates the first intermediate image and the second intermediate image from the parallel light by modulating a spatial distribution of the component of the parallel light according to writing information;
The image display apparatus in any one of Claims 2-5.

Images