KR20090100231A - Projection optical system and head-up display device - Google Patents

Abstract

PURPOSE: A projection optical system, a head-up display device for reducing power consumption are provided to project uniform virtual image and bright image which is displayed on a small liquid crystal display panel. CONSTITUTION: A projection optical system includes an illuminating unit, a relay lens(21) and a projection lens(L1). The illuminating unit irradiates a fan from the rear of the LCD panel. The illuminating unit radiates the indication light from the frontal surface of the LCD panel. The indication light has the information of the image indicated on the LCD panel. The relay lens condenses the indication light. The relay lens images as the real image enlarges the image indicated on the LCD panel. The projection lens reflects the expanded real image of the image imaged by the relay lens to the reflecting surface.

Description

PROJECTION OPTICAL SYSTEM AND HEAD-UP DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head-up display device in which an image is projected onto a windshield of an automobile or an aircraft, and the image is observed as a virtual image over the windshield.

BACKGROUND ART A head-up display apparatus is known in which a display light of an image is reflected from a windshield of an automobile toward a driver (observer) so that an image of a device such as a speedometer can be observed as a virtual image. Since the image of the instrument displayed by the head-up display device is enlarged and displayed as a virtual image at a position 2 m or more away from the driver over the windshield, the driver can observe the display image with almost no change in the direction of vision or the field of view as well as the normal front view. It is supposed to be.

The optical unit used in the head-up display device is composed of an image display panel, an illumination light source, and a projection optical system. A transmissive liquid crystal display panel is often used for an image display panel, and a backlight is disposed behind the image display panel. The illumination light by the backlight penetrates the liquid crystal display panel, becomes a display light having information of an image displayed on the liquid crystal display panel, and enters the projection optical system. The projection optical system enlarges and projects the display light on the windshield, and displays the enlarged virtual image on the driver as described above.

As a projection optical system used for a head-up display apparatus, the enlarged projection of the image displayed on a liquid crystal display panel with a mirror lens (patent document 1), the enlarged projection with a magnifying lens (patent document 2), etc. are known, for example. .

[Patent Document 1] Japanese Patent Publication No. 2006-11168

[Patent Document 2] Japanese Patent Publication No. 2007-148092

However, due to the relationship between the size of the virtual image displayed when the display image is directly magnified and projected by a mirror lens or an enlarged lens and the distance from the projection optical system to the virtual image displayed, the size of the image displayed on the liquid crystal display panel is somewhat It is necessary. For this reason, a large liquid crystal display panel must be used, and accordingly, a large backlight is required, making it difficult to miniaturize, reduce the cost, and reduce the power consumption of the head-up display device.

In addition, when the size of the virtual image displayed by the head-up display device is about 150 mm, which is easy for the driver to observe, the projection optical system can be observed with both eyes even if the driver moves about 20 mm from side to side. It is necessary to make the exit pupil of about 100mm in size. At this time, in consideration of reflecting the display light from the windshield positioned between the driver and the virtual image displayed, the aperture of the projection optical system needs to be 150 mm. When the distance from the projection optical system to the virtual image is D, the projection magnification is β, and the focal length of the projection optical system is f, x = (1 + β) × f (imaging formula), for example, 0.8 type liquid crystal display. Considering the case where the width of the panel 16 mm is enlarged 9 times to display a 144 mm virtual image, the focal length of the projection optical system is 100 mm. However, since a lens having an aperture of 150 mm and a focal length of 100 mm has an F value of 0.67 and becomes a very bright lens, it is difficult to realize.

Therefore, instead of directly magnifying and projecting the image displayed on the liquid crystal display panel, a projection optical system is used to form an image enlarged by a relay lens on the screen, and further enlarge and project the enlarged image by the projection lens. Is considered. However, this projection optical system has a problem in that the utilization efficiency of illumination light is poor, and the virtual image displayed even if it uses the backlight of the same grade as before will become darker than before. On the contrary, in order to display a virtual image with the same brightness | luminance as the conventional head-up display apparatus, it is necessary to use the backlight of very high brightness, and there exists a problem that installation space, cost, and power consumption increase.

Patent Document 2 discloses a projection optical system using an illumination light by connecting a hollow image without using a screen or the like by a relay lens and aligning the NA and the chief ray angle of the projection optical system. The projection magnification is large and NA becomes very large on the liquid crystal display panel side.

As is well known, the liquid crystal display panel has a limited viewing angle at which an image having good contrast and brightness can be observed, and this viewing angle is narrow. The projection optical system, which has a large NA on the liquid crystal display panel side, also uses display light emitted at an angle greater than the viewing angle of the liquid crystal display panel, thereby increasing utilization efficiency of illumination light, but shading occurs in the color and contrast of the virtual image to be displayed. There is a problem to say. In addition, in order to prevent the color of the virtual image to be displayed and the shadow of the contrast, when illuminating according to the chief ray angle of the projection optical system, the chief ray is diverged toward the back side (backlight side), so that the backlight must be larger than the conventional one. There is.

The present invention has been made in view of the above problems, and an object thereof is to provide a projection optical system capable of projecting an image displayed on a small liquid crystal display panel as a bright and uniform virtual image. In addition, an object of the present invention is to provide a bright and uniform virtual image and to provide a head-up display device with low power consumption and a small size.

The projection optical system of the present invention reflects display light emitted from a transmissive liquid crystal display panel to the observer side with a reflection surface facing an observer at a predetermined position to enlarge and project the image displayed on the liquid crystal display panel as a virtual image over the reflection surface. Illumination means for irradiating light from a rear of the liquid crystal display panel to a projection optical system and emitting display light having information of an image displayed on the liquid crystal display panel from a front surface of the liquid crystal display panel; and a display emitted from the liquid crystal display panel. A relay lens for condensing light and enlarging an image displayed on the liquid crystal display panel to form an image as a real image, and a projection lens for enlarging and projecting an enlarged real image of the image formed by the relay lens onto the reflective surface; The focal length of the relay lens is f1 and the image side is the forward direction. B is the distance from the main principal point of the relay lens to the exit pupil of the relay lens, f3 is the focal length of the projection lens, and the distance from the main principal point of the relay lens to the actual image formed by the relay lens b, The distance from the actual image to the object-side main point of the projection lens is δ, the distance from the image-side main point of the projection lens to the observer is WD, and the size of the range in which the viewpoint of the observer moves is Dpo, the exit pupil of the relay lens. When the size is Dpr2, 0.5 <α / f1 <15, f3 = WD × (−α + b + δ) / (− α + b + δ + WD), Dpo = Dpr2 × WD / (− α + b + δ) is satisfied.

Further, when the distance from the observer to the virtual image is L and the magnification of the virtual image relative to the size of the image displayed on the liquid crystal display panel is M, the condition of 1 <L / (M × Dpo) <4 is set. It is characterized by satisfying.

The head-up display device of the present invention is characterized by including the above-described projection optical system.

(Effects of the Invention)

According to the present invention, it is possible to provide a projection optical system capable of projecting an image displayed on a small liquid crystal display panel as a bright and uniform virtual image. In addition, it is possible to provide a bright and uniform virtual image and to provide a head-up display device with low power consumption and a small size.

As shown in FIG. 1, the head-up display device 10 is disposed on a dashboard 12 of the vehicle 11, and the value of the instruments such as a speedometer is displayed in front of the driver (observer) 14. It is displayed over the windshield 13 (reflective surface).

This head-up display device 10 incorporates a small liquid crystal display panel 16 (see Fig. 2), and displays the value of the instrument on the liquid crystal display panel. The head-up display device 10 enlarges and projects the display light 26 emitted from the liquid crystal display panel 16 toward the windshield 13 by the projection optical system 20 (see FIG. 2). The projected display light 26 is reflected in the direction of the driver 14 in the windshield 13.

The head-up display device 10 does not display a real image on the windshield 13, but displays a virtual image Iv at a position D of the driver D 14 over the windshield 13.

The distance D on which the virtual image Iv is displayed is sufficiently long so that the virtual image Iv can be seen even when the eyes are hardly moved and the eye focus is hardly adjusted. For example, the virtual image Iv is displayed at a distance of 2 m or more from the driver.

As shown in FIG. 2, the head-up display device 10 includes a liquid crystal display panel 16, a backlight 17 (lighting means), and a projection optical system 20.

The liquid crystal display panel 16 displays values of various instruments such as a speedometer, a tachometer, a water thermometer, and a fuel gauge. In addition, the liquid crystal display panel 16 is of a transmissive type, and illumination light is irradiated from the backlight 17 provided at the rear, and transmits the display light 26 having information of the displayed image to the front.

The backlight 17 is made of, for example, a white LED or the like, and illuminates the liquid crystal display panel 16 in the same manner from the rear. In addition, the backlight 17 is not limited to irradiating white illumination light by a white LED, but may illuminate illumination light of a desired color. For example, you may comprise with monochromatic LEDs, such as red, green, and blue, and you may make it display an image in a desired color, combining some of these monochromatic LEDs. In addition, the backlight 17 is not limited to LED, but other known lamps or the like may be used.

The projection optical system 20 is composed of a relay lens 21 and a projection lens L1. After the image displayed on the liquid crystal display panel 16 is enlarged and imaged as the real image Ir, the actual image Ir is further enlarged. Project onto the windshield 13. The relay lens 21 is configured such that the liquid crystal display panel 16 side (object side) is telecentric. The relay lens 21 collects the telecentric display light 26 emitted from the liquid crystal display panel 16, enlarges an image displayed on the liquid crystal display panel 16, and forms an image as an actual image Ir. The projection lens L1 is, for example, a Fresnel lens, and enlarges and projects the real image Ir formed by the relay lens 21 onto the windshield 13.

The projection optical system 20 determines the distance from the upper main point Hr2 of the relay lens 21 with the focal length of the relay lens 21 to the forward direction to the exit pupil Pr2 of the relay lens 21. It is comprised so that the condition of following formula (1) may satisfy | fill.

The condition shown in equation (1) is to limit the position of the exit pupil Pr2 of the relay lens 21 and is substantially parallel to the optical axis of the relay lens 21 in the display light 26 emitted from the liquid crystal display panel 16. It is a condition for efficiently using only the so-called telecentric display light 26, which can be regarded as &quot; When the value of (alpha) / f1 exceeds the upper limit and the lower limit of Formula (1), out of the display light 26 radiate | emitted from the liquid crystal display panel 16, the display light 26 other than the viewing angle of the liquid crystal display panel 16 is also a virtual image ( It is used for the display of Iv), and the virtual image Iv causes shading to occur in luminance and contrast.

In addition, the projection optical system 20 determines the focal length of the projection lens L1 as f3, and the distance from the upper main point Hr2 of the relay lens 21 to the actual image Ir formed by the relay lens 21 b, When the distance from the actual image Ir to the object-side main point Hp1 of the projection lens L1 is δ and the distance from the image-side main point Hp2 of the projection lens L1 to the driver 14 is WD, the following equation It is comprised so that the condition of 2 may be satisfied.

The condition shown in Equation 2 is to determine the focal length of the projection lens L1 according to the position (value of α) of the exit pupil Pr2 of the relay lens 21 determined to satisfy the condition of Equation 1, and the relay It is a condition that the position of the exit pupil Pr2 of the lens 21 and the position of the observer range Po become conjugate.

In addition, the projection optical system 20 sets the size of the range (hereinafter referred to as the observer range Po) of the driver's viewpoint to Dpo and the size of the exit pupil Pr2 of the relay lens 21 to Dpr2. It is comprised so that the condition of Formula (3) may be satisfied. In addition, the size Dpo of the observer range Po is, for example, the diameter when the observer range is made circular, and the diagonal length when the observer range Po is made rectangular, for example. Let it be the length used as a reference | standard of the range Po. In addition, the magnitude | size of the exit pupil Pr2 means the diameter of the exit pupil Pr2.

The condition shown in equation (3) is the size (Dpr2) and the observer of the exit pupil (Pr2) of the relay lens (21) in accordance with the position of the exit pupil (Pr2) of the relay lens (21) determined to satisfy the condition of equation (1). The ratio of the size Dpo of the range Po is determined, and the most high luminance and high contrast virtual image Iv is obtained by using the telecentric display light 26 determined by Equation 1 efficiently. It is condition to be able to observe in (Po).

In addition, the projection optical system 20 sets the distance from the driver 14 to the virtual image Iv as L, and the magnification ratio of the virtual image Iv with respect to the size of the image displayed on the liquid crystal display panel 16 is M as follows. It is comprised so that the condition of Formula (4) may be satisfied.

The effective F number on the liquid crystal display panel 16 side of the relay lens 21 is proportional to L / (M × Dpo). Therefore, when the value of L / (MxDpo) is less than the lower limit of the expression (4), the F number of the relay lens 21 becomes small, and aberration cannot be sufficiently corrected. On the other hand, when the value of L / (M × Dpo) exceeds the upper limit of the equation (4), the magnification of the relay lens 21 decreases, and when the virtual image Iv of a predetermined luminance is to be displayed, the size of the liquid crystal display panel 16 is increased. Cause.

As the projection optical system 20 is configured to satisfy the conditions of the above-described equations (1) to (4), as shown schematically in FIG. 3 (A), the relay lens 21 from the liquid crystal display panel 16. Only the telecentric display light 26 emitted substantially parallel to the optical axis of is used for the display of the virtual image Iv. This telecentric display light 26 is enlarged and imaged by the relay lens 21 into the real image Ir, and this real image Ir is further enlarged by the projection lens L1 to the windshield 13. Projected.

In FIG. 3, although not shown in the drawing to avoid the trouble, the display light 26 reflected by the windshield 13 is incident on the eyes of the driver 14 who observes at a point within the observer range Po. Since the telecentric display light 26 emitted from one point of the liquid crystal display panel 16 is incident by the projection lens L1 to widen the solid angle within the observer range Po, the driver 14 is the same as long as they are the same. The virtual image Iv which enlarged the real image Ir further at the position of the virtual intersection of the display light 26 radiate | emitted from the point is observed over the windshield 13.

For example, as shown schematically in FIG. 3B, when the driver 14 observes the virtual image Iv from the lower end of the observer range Po, the display light 26a is connected to the driver 14. Incident on the eye. The display light 26a is slightly obliquely upward from the liquid crystal display panel 16, but the telecentric display light 26a is emitted at a viewing angle which can be regarded as a normal value to be outputted by the brightness and contrast. to be. In addition, even when the driver 14 observes the virtual image Iv from the upper end of the observer range Po, the virtual image Iv observed from the lower end of the observer range Po is also slightly oblique to the liquid crystal display panel 16. It is displayed by the telecentric display light 26 which emits downward but whose luminance and contrast are normal.

Such a virtual image Iv, which the driver 14 observes from the position in the observer range Po, is displayed by the telecentric display light 26 as the upper end, the lower end, or the center of the observer range Po. The virtual image Iv is similarly displayed by the telecentric display light 26 even when the virtual image Iv is observed from any position within the observer range Po not only in one particular point.

In addition, as shown in FIG. 3, in order to use the telecentric display light 26 for displaying the virtual image Iv, it is not necessary to arrange the actual aperture within the relay lens 21. Since the projection optical system 20 is configured to satisfy the conditions of the equations (1) to (4), when the virtual image (Iv) is observed from the observer range (Po), display light incident on the eyes of the driver 14 ( 26 is automatically limited to the display light 26 emitted from the actual exit pupil (hereinafter, the actual pupil) inside the relay lens 21 which is conjugate with the exit pupil Pr2 of the relay lens 21. The size of the actual motion 27 of the relay lens 21 may be equal to or larger than the airspace of the observer range Po, or the projection optical system 20 may be represented by the equations (1) through (1). By being configured to satisfy the condition of Equation 4, the size of the actual cavity 27 is the same size as the conjugate phase of the observer range Po.

Moreover, since the projection optical system 20 is comprised so that the conditions of Formula (1)-(4) mentioned above may be satisfy | filled, as shown typically in FIG. 4, of the observer range Po and the relay lens 21, The exit pupils Pr2 are located in the airspace. As a result, all of the display light 26 emitted from the liquid crystal display panel 16 at the telecentric viewing angle enters the observer range Po. Therefore, among the display light 26 emitted from the liquid crystal display panel 16, the display light 26 emitted at a viewing angle having normal luminance and contrast is most efficiently used for displaying the virtual image Iv.

In particular, as described above, the object-side main point Hr2 of the relay lens 21 and the exit pupil Pr2 of the relay lens 21 do not coincide with each other, and as described above, they are relayed from the object-side main point Hr2 of the relay lens 21. The range and observer range of the telecentric display light 26 emitted from the liquid crystal display panel 16 by setting the distance α to the exit pupil Pr2 of the lens 21 within the range of the condition of Equation 1 (Po) is matched. Thus, even when the virtual image Iv is observed from any position in the observer range Po, only the telecentric display light 26 in which the luminance or contrast suitable for displaying the virtual image Iv does not appear in the virtual image ( It is used for the display of Iv).

In addition, the projection optical system 20 is capable of correcting aberration sufficiently while the value of L / (M × Dpo) is within the range of the condition of Equation 4, and with a sufficiently small backlight 17 The virtual image Iv of high brightness and high contrast is displayed.

Below, the specific example of the projection optical system 20 is shown as Examples 1-3. In addition, the size of the image displayed on the liquid crystal display panel 16 is 30 mm x 10 mm in Example 1, and 15 mm x 5 mm in Examples 2 and 3, and the distance from the driver 14 to the virtual image Iv. It was comprised so that (L) became 2m. In addition, in the lens data shown in each Example, the unit of L, f1, f3, (alpha), b, (delta), Dpo, Dpr2, and WD was set to mm.

Example 1

As shown in FIG. 5, the projection optical system 31 has the projection lens L1 in which the Fresnel surface was formed in order from the image side, the 2nd lens L2, the 3rd lens L3, and the 4th lens L4. The relay lens 32 is composed of three lenses. Each surface of the lens which comprises these projection optical system 31 is represented by Si using surface number i (i = 1-8) sequentially from an image side. In addition, the space | interval (surface space | interval on the optical axis of the surface Si and the surface Si + 1) between adjacent surfaces Si is set to Di.

As the lens data of the projection optical system 31, the number of lenses is sequentially determined from the curvature radius Ri (mm) of each surface Si, the surface spacing Di (mm), and the image side in order from j (j = 1 to 4). In Table 1, the refractive index Ndj of each lens Lj and the Abbe's number υdj of each lens Lj with respect to the d line (587.6 nm) are shown in Table 1).

In addition, the lower end of Table 1 shows the focal length f1 of the relay lens 32, the distance α from the upper main point Hr2 of the relay lens 32 to the exit pupil Pr2 of the relay lens 32, and the projection. The focal length f3 of the lens L1, the distance b from the image main main point Hr2 of the relay lens 32 to the actual image Ir, and the object side main point Hp1 of the projection lens L1 from the actual image Ir. Distance (δ), distance WD from the upper main point Hp2 of the projection lens L1 to the observer range Po, the size Dpo of the observer range Po, and the output of the relay lens 32 The size Dpr2 of the pupil Pr2, the magnification M of the virtual image Iv with respect to the image on the liquid crystal display panel 16, the distance L from the observer range Po to the virtual image Iv, α / The value of f1 and the value of L / (MxDpo) are shown.

As shown in Table 1, each surface of the second lens L2 to the fourth lens L4 constituting the relay lens 32 has a spherical surface, and the liquid crystal display panel 16 of the fourth lens L4. The distance from the surface S8 on the () side (object side) to the image display surface of the liquid crystal display panel 16 is 52.720 mm.

As can be seen from Table 1, the projection optical system 31 has α / f1 = 0.66, which satisfies the condition of Expression (1). In addition, the focal length f3 of the projection lens L1 is a value satisfying the condition of Equation 2 calculated from the values of α, b, δ, and WD, and the size Dpo of the observer range Po is It becomes a value which satisfy | fills the conditions of Formula (3) computed from (alpha), b, (delta), and Dpr2. Similarly, L / (M x Dpo) = 3.98, which satisfies the condition of Expression (4).

Spherical aberration of the projection optical system 31 is shown in Fig. 6A, astigmatism is shown in Fig. 6B, and distortion is shown in Fig. 6C. The spherical aberration is represented by the solid line for the e line (wavelength 546.1 nm), the dashed line for the g line (wavelength 435.8 nm), and the two-dot chain line for the C line (wavelength 656.3 nm). In addition, astigmatism shows the thing of the sagittal direction by a solid line, and the thing of the tangential direction by a broken line.

7A to 7D show the lateral aberration in the tangential direction in the case of the image heights 0 mm, 25 mm, 75 mm, and 80 mm of the projection optical system 31. 7E to 7G show the lateral aberration in the sagittal direction with respect to the case of the image height 25mm, 75mm, 80mm of the projection optical system 31.

As mentioned above, since the projection optical system 31 of Example 1 is comprised so that the conditions of Formula (1)-(4) may be satisfied, the telecentric display light 26 radiate | emitted from the small liquid crystal display panel 16 When the virtual image Iv is observed from any position of the observer range Po, the image can be projected as a bright and uniform virtual image Iv without causing any shadows to appear in brightness or contrast. In addition, when the projection optical system 31 is mounted, the head-up display device 10 can project a bright and uniform virtual image Iv to the small liquid crystal display panel 16 and the backlight 17, thereby reducing the power consumption. Compact and inexpensive.

Example 2

As shown in FIG. 8, the projection optical system 41 has the projection lens L1, the 2nd lens L2, the 3rd lens L3, the 4th lens L4, and the 5th lens L5 in order from an image side. And a relay lens 42 composed of five lenses of the sixth lens L6. Each surface of the lens which comprises these projection optical systems 41 is shown by surface number i (i = 1-11) in order from an image side. In addition, the space | interval (surface space | interval on the optical axis of the surface Si and the surface Si + 1) between adjacent surfaces Si is set to Di. In addition, the third lens L3 and the fourth lens L4 constituting the relay lens 42 are joined at the surface S6.

As the lens data of the projection optical system 41, the lens number j is j (j = 1 to 6) in order from the curvature radius Ri (mm) of each surface Si, each surface space Di (mm), and from the image side. Table 2 shows the refractive index Ndj of each lens Lj and the Abbe number υdj of each lens Lj with respect to the d line.

Further, at the lower end of Table 2, the distance from the focal length f1 of the relay lens 42 and the upper main point Hr2 of the relay lens 42 with the image side in the forward direction to the exit pupil Pr2 of the relay lens 42. (α), the focal length f3 of the projection lens L1, the distance b from the image-side main point Hr2 of the relay lens 42 to the actual image Ir, and the actual image Ir of the projection lens L1. Distance (δ) to object-side main point Hp1, distance from upper main point Hp2 of projection lens L1 to observer range Po, WD, observer range Po, size Dpo, relay lens The size Dpr2 of the exit pupil Pr2 of 42, the magnification M of the virtual image Iv with respect to the image on the liquid crystal display panel 16, and the distance from the observer range Po to the virtual image Iv ( L), the value of (alpha) / f1, and the value of L / (MxDpo) are shown.

As shown in Table 2, the space | interval from the surface S11 of the liquid crystal display panel 16 side (object side) of the 6th lens L6 to the image display surface of the liquid crystal display panel 16 was 19.412 mm. In addition, as for the lens which comprises the relay lens 42, surface S2, surface S4, surface S6-surface S11 were spherical, and surface S1, surface S3, and surface S5 were aspherical. Aspherical surface S1, surface S3, and surface S5 have the specific shape x the length of the perpendicular | vertical line which fell to the tangent plane of an aspherical vertex from the point on the aspherical surface of height y and height y from an optical axis, and the radius of curvature in the vicinity of an aspherical vertex. It is represented by the following formula (5) using (r), the cone coefficient K, and the aspherical coefficient A2i of the second order (i = 2 to 5). In addition, the aspherical surface coefficient of surface S1, surface S3, and surface S5 was made into the value shown in Table 3 specifically.

As can be seen from Table 2, the projection optical system 41 has α / f1 = 0.96, which satisfies the condition of Expression (1). In addition, the focal length f3 of the projection lens L1 is a value satisfying the condition of Equation 2 calculated from the values of α, b, δ, and WD, and the size Dpo of the observer range Po is It becomes a value which satisfy | fills the conditions of Formula (3) computed from (alpha), b, (delta), and Dpr2. Similarly, L / (M × Dpo) = 1.43, which satisfies the condition of Expression (4).

Spherical aberration of the projection optical system 41 is shown in Fig. 9A, astigmatism is shown in Fig. 9B, and distortion is shown in Fig. 9C. 10 (A)-(D), the transverse aberration in the tangential direction is shown in the case of the image height 0mm, 25mm, 75mm, 80mm, and the image height 25mm, 75mm, 80mm in FIGS. 10 (E)-(G). In this case, the lateral aberration in the sagittal direction is shown. In addition, the description of each of these aberrations is the same as that of the first embodiment.

As described above, since the projection optical system 41 of the second embodiment is configured to satisfy the conditions of Equations 1 to 4, the telecentric display light 26 emitted from the small liquid crystal display panel 16 is provided. By efficiently utilizing, the image displayed on the small liquid crystal display panel 16 can be projected as a bright and uniform virtual image Iv without generating shadows in luminance or contrast. In addition, when the projection optical system 41 is mounted, the head-up display device 10 can project a bright and uniform virtual image Iv to the small liquid crystal display panel 16 and the backlight 17, thereby reducing the power consumption. It is compact and inexpensive.

Example 3

As shown in FIG. 11, the projection optical system 51 consists of the projection lens L1 in which the Fresnel surface was formed in the image side in order from an image side, and the seven lenses of 2nd lens L2-the 8th lens L8. It consists of a relay lens 52. Each surface of the lens which comprises these projection optical systems 51 is represented by Si using surface number i (i = 1-15) in order from an image side. In addition, the space | interval (surface space | interval on the optical axis of the surface Si and the surface Si + 1) between adjacent surfaces Si is set to Di. In addition, the fifth lens L5 and the sixth lens L6 constituting the relay lens 52 are joined at the surface S10.

As the lens data of the projection optical system 51, the lens number is j (j = 1 to 8) in order from the radius of curvature Ri (mm) of each surface Si, the distance of each surface Di (mm), and the image side. Table 4 shows the refractive index Ndj of the angle lens Lj and the Abbe number υdj of each lens Lj with respect to the d line.

In addition, the lower end of Table 4 shows the focal length f1 of the relay lens 52, the distance α from the upper main point Hr2 of the relay lens 52 to the exit pupil Pr2 of the relay lens 52, and the projection. The focal length f3 of the lens L1, the distance b from the image main main point Hr2 of the relay lens 52 to the actual image Ir, and the object side main point Hp1 of the projection lens L1 from the actual image Ir. Distance (δ), distance WD from the upper main point Hp2 of the projection lens L1 to the observer range Po, the size Dpo of the observer range Po, and the output of the relay lens 52 The size Dpr2 of the pupil Pr2, the magnification M of the virtual image Iv with respect to the image on the liquid crystal display panel 16, the distance L from the observer range Po to the virtual image Iv, α / The value of f1 and the value of L / (MxDpo) are shown.

 As shown in Table 4, each surface of the second lens L2 to the eighth lens L8 constituting the relay lens 52 is all spherical, and the liquid crystal display panel 16 of the eighth lens L8 is formed. The distance from the surface S15 on the) side (object side) to the image display surface of the liquid crystal display panel 16 is 19.886 mm.

As can be seen from Table 4, the projection optical system 51 has α / f1 = 0.68, and satisfies the condition of Expression (1). In addition, the focal length f3 of the projection lens L1 is a value satisfying the condition of Equation 2 calculated from the values of α, b, δ, and WD, and the size Dpo of the observer range Po is It becomes a value which satisfy | fills the conditions of Formula (3) computed from (alpha), b, (delta), and Dpr2. Similarly, L / (M x Dpo) = 2.00, which satisfies the condition of Expression (4).

Spherical aberration of the projection optical system 51 is shown in Fig. 12A, astigmatism is shown in Fig. 12B, and distortion is shown in Fig. 12C. 13 (A) to (D), the transverse aberration in the tangential direction is shown in the case of the image height 0 mm, 25 mm, 75 mm, and 80 mm, and the image height 25 mm, 75 mm, and 80 mm in FIGS. 13E and (G). In this case, the lateral aberration in the sagittal direction is shown. In addition, the description of each of these aberrations is similar to that of the first embodiment.

As described above, since the projection optical system 51 of Example 3 is configured to satisfy the conditions of Equations 1 to 4, the telecentric display light 26 emitted from the small liquid crystal display panel 16 is provided. Even when observing the virtual image Iv from any position of the observer range Po using efficiently, it is possible to project as a bright and uniform virtual image Iv without generating shadows in luminance or contrast. In addition, when the projection optical system 51 is mounted, the head-up display device 10 can project a bright and uniform virtual image Iv to the small liquid crystal display panel 16 and the backlight 17, thereby reducing the power consumption. It is compact and inexpensive.

In addition, although the above-mentioned embodiment uses refractive lenses, such as a Fresnel lens, as projection lens L1, you may use not only this but optical members with lens effects, such as a mirror aspherical lens, as projection lens L1. . In addition, although the projection lens L1 shows the example which consists of one refractive lens in embodiment mentioned above, you may comprise the projection lens L1 with several refractive lenses, and there exists a lens effect different from a refractive lens. The optical lens may be combined to constitute the projection lens L1.

In addition, although the above-mentioned embodiment uses the 0.8 type liquid crystal display panel of 15 mm x 5 mm, and the liquid crystal display panel of 30 mm x 10 mm as a liquid crystal display panel 16, it is not limited to this, A aspect ratio and the size of a display area differ. You may use another liquid crystal display panel. Similarly, the value determined according to the type, use, etc. of the head-up display device, such as the size of the virtual image Iv to be displayed, is not limited to the value shown in the above-described embodiment, but may be appropriately set.

In the above-described embodiment, the head-up display device of the present invention is described as an example for automobiles. However, the head-up display device of the present invention can be suitably used for other things such as aircrafts and ships. As described above, in the case of applying the head-up display device of the present invention in addition to the automobile, the concave mirror is detailed while the surface of the non-rotationally symmetric aspherical surface is formed in accordance with the shape of the reflective surface (windshield in the automobile) for expanding and projecting the display light. It is necessary to determine the face shape individually. Moreover, since the state of the inclination and curvature of a windshield differs according to a vehicle model etc., the same adjustment is required even when using the head-up display apparatus of this invention for an automobile.

In addition, since the head-up display device is installed in a dashboard of a vehicle or the like, it is preferable that each part constituting the head-up display device is excellent in heat resistance.

1 is an explanatory diagram showing an outline of a head-up display device.

It is explanatory drawing which shows typically the structure of a projection optical system.

3 is an explanatory diagram schematically showing an optical path of display light.

It is explanatory drawing which shows typically the exit pupil of a relay lens.

5 is a cross-sectional view of the projection optical system of Example 1. FIG.

6 is an aberration diagram showing spherical aberration, astigmatism, and distortion aberration of the projection optical system of Example 1. FIG.

7 is a horizontal aberration diagram of the projection optical system of Example 1. FIG.

8 is a cross-sectional view of the projection optical system of Example 2. FIG.

9 is aberration diagrams showing spherical aberration, astigmatism, and distortion aberration of the projection optical system of Example 2. FIG.

10 is a horizontal aberration diagram of the projection optical system of Example 2. FIG.

11 is a cross-sectional view of the projection optical system of Example 3. FIG.

12 is aberration diagrams showing spherical aberration, astigmatism, and distortion aberration of the projection optical system of Example 3. FIG.

13 is a horizontal aberration diagram of the projection optical system of Example 3. FIG.

<Explanation of symbols for the main parts of the drawings>

10: head-up display device 14: driver (observer)

16 liquid crystal display panel 17 backlight (lighting means)

20, 31, 41, 51: projection optical system 21, 32, 42, 52: relay lens

26: display light L1: projection lens

f1: focal length of the relay lens f3: focal length of the projection lens

Iv: virtual image Ir: real

Pr2: Exit pupil of the relay lens Hr2: Upper pub of the relay lens

Po: Observer range Hp2: Image main point of the projection lens

Hp1: Object side principal point of the projection lens

Claims (3)

A projection optical system for reflecting a display light emitted from a transmissive liquid crystal display panel by a reflecting surface facing an observer at a predetermined position to the observer side and magnifying and projecting the image displayed on the liquid crystal display panel as a virtual image over the reflecting surface: Illumination means for irradiating light from behind the liquid crystal display panel to emit display light having information of an image displayed on the liquid crystal display panel from a front surface of the liquid crystal display panel; A relay lens for condensing the display light emitted from the liquid crystal display panel to enlarge an image displayed on the liquid crystal display panel and to form an image as a real image; and A projection lens configured to enlarge and project the enlarged real image of the image formed by the relay lens onto the reflective surface; F1 is the focal length of the relay lens, the distance from the upper main point of the relay lens with the image side to the forward direction to the exit pupil of the relay lens is α, the focal length of the projection lens is f3, and the upper main point of the relay lens is B, the distance from the actual image to the object-side principal point of the projection lens, δ, the distance from the image-side principal point of the projection lens to the observer, and the viewpoint of the observer is shifted. When the size of the range to be Dpo and the size of the exit pupil of the relay lens are Dpr2, 0.5 <α / f1 <1.5, f3 = WD × (−α + b + δ) / (− α + b + δ + WD), Dpo = Dpr2 × WD / (-α + b + δ) The projection optical system, which satisfies the condition of. The method of claim 1, wherein when the distance from the observer to the virtual image is L, the magnification of the virtual image relative to the size of the image displayed on the liquid crystal display panel is M. 1 <L / (M × Dpo) <4 The projection optical system, which satisfies the condition of. A head-up display device comprising the projection optical system according to claim 1.

Images