JP6249366B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device, and in particular, when a narrow viewing angle is acceptable, the power consumption is achieved by concentrating the light of all image information on the position of one person's eye who wants to observe the image. The present invention relates to an aerial imaging type image display apparatus in which

  In recent years, low power consumption has become important, and it is also an important issue for displays. Liquid crystal displays (abbreviated as LCD), plasma displays, and organic EL displays, which are general displays, all diffuse light from the display surface in all directions and diffuse light into space, but are actually used. Only the light entering the 2 to 8 mm aperture, which is the pupil of the human eye, is used, and when there is only one observer, the light utilization efficiency is the solid angle range in which the entire light from the display surface diffuses The area ratio of the solid angle range (a very small area in the hemisphere) diffusing toward the observer's eyes with respect to the (hemisphere) is very bad, 1/1000 to 1/10000.

  Therefore, an optical surface in which all the image information light is collected uniformly in an angular and spatial manner only in the position of (or in the vicinity of) the eye of a single person who is observing the image is formed in space. Therefore, an ultra low power consumption of about 1/10 to 1/100 can be realized by a display of an image viewing system (for example, see Patent Document 1 “Iris surface space imaging control type image display device”).

Furthermore, in recent years, attention has been paid to image display floating in the air for immersive feeling and stereoscopic display. As a technique related to this, a display unit that displays an image of an object, and an image floating unit that floats an image displayed on the display unit in an external space of the display unit, the image floating unit is connected to the display unit. A space floating image display device comprising an equal-magnification imaging optical system that forms an upright image or an inverted image at the same magnification as the image displayed on the display means in the external space of the display means regardless of the distance of the like Baiyuizo optical system includes a lens of n + 1 sheets focal length is f ₁ (n is an integer of 1 or more), an n-lenses the focal length is f _2, and the focal length Either _one of the lens with f ₁ or the lens with the focal length f ₂ or both are variable focal length lenses, and the lens with the focal length f _{1 and} the lens with the focal length f ₂ are alternately And Are arranged at intervals, the interval d of two of the adjacent lenses is represented by the following formulas the magnification of the imaging of the light passing through the k-number of the lens when the M _k (5) to Equation (8) A recurrence formula represented by
M _k = −M _k−1 L _k / (d _k−1 −L _k−1 ) (5)
M ₀ = 1 (6)
L _k = 1 / {1 / (f _{2− (k mod2)} −1 / (d _k−1 −L _k−1 )} (7)
d _k = 0 (@ k = 0), d (@ k ≠ 0) (8)
_Has proposed a spatial floating image display device (see claim 1 of Patent Document 2) characterized by satisfying M _{k = 2n + 1} = 1 or −1 and having a value independent of L ₀ .

JP 2013-025052 A Japanese Patent No. 4503484

  The above-mentioned “optical surface in which the light of all image information is uniformly collected in an angular and spatial manner” is referred to as a “spatial imaging iris surface”. When the size of the spatial imaging iris surface is set small, ultra-low power consumption is realized, but the visible range (referred to as an observation region) is narrowed. Conversely, if the size of the spatial imaging iris surface is set large, low power consumption is difficult to achieve, but the observation area is widened. If this trade-off is effectively utilized in accordance with the purpose of use of the display, a large low power consumption effect can be expected. For example, in-vehicle head-up displays (abbreviated as HUD) where the viewing position with respect to the display is substantially determined, and image display devices for videophones, the effective use of the trade-off exhibits a significant low power consumption effect. Will do. Furthermore, in recent years, attention has been paid to image display floating in the air for immersive feeling and stereoscopic display. Again, a large low power consumption effect can be expected by effectively utilizing the trade-off.

  However, the technology that can adjust the size and observation area of the spatial imaging iris surface according to the purpose of use of the display, contribute to a large reduction in power consumption, and can also display an image floating in the air. However, it has not been proposed.

Note that the technique of Patent Document 2 is limited to an aerial image of the same magnification, and there is no description of an enlarged (or reduced) aerial image. Further, the structure includes n + 1 lenses (n is an integer of 1 or more) having a focal length f ₁ and n lenses having a focal length f ₂ , and the focal length f ₁ and the focal length are f. _{The two} lenses are alternately arranged at equal intervals. In addition, the lens having the focal length f ₂ is merely a lens (having a negative focal length) for making the optical system thin. Therefore, with the technique of Patent Document 2, it is impossible to adjust the size of the spatial imaging iris surface and the observation area in accordance with the purpose of use of the display.

  Therefore, the present invention has an object to provide an image display device that can adjust the size and observation area of the spatial imaging iris surface in accordance with the purpose of use of the display and that can also display an image displayed in the air. Problem to be solved).

The present invention is the result of repeated studies by the present inventors in order to solve the above-mentioned problems, and the gist thereof is as follows.
(1) One of the two lens groups including one lens or a plurality of lenses and having a combined focal length of the focal length f ₁ is set as an incident side lens, and the other is set as an output side lens. Is set to within f ₁ ± 20%, an image display device for forming a primary image on the main plane incident side of the incident side lens is installed, and the position information of the primary image is set to the angle Converting into the information, setting the main plane of the exit side lens to the front focal plane part of the reflection type mirror of the focal length f ₂ , converting the angle information which is the conversion output information of the exit side lens into the position information, A secondary image, which is a similar image of the primary image, is formed on the rear focal plane in the air on the exit side of the reflective mirror, and an infinite triangle type observation is performed on the exit side of the secondary image. An image table characterized by a configuration for forming an area Indicating device. (This is called the present invention [1])
(2) In the above (1), the main plane of the exit side lens is set to be more than the front focal plane portion of the reflective mirror, with the relative positional relationship of the entrance side lens, the exit side lens, and the image display device unchanged. By displacing backward, an infinite pentagonal type or diamond type observation region that is closer to the secondary image than the infinity triangular type is formed on the emission side of the secondary image. An image display device characterized by that. (This is called the present invention [2])
(3) In the above (1) or (2), the reflective mirror is made of a transparent optical material and a dome-shaped optical element. Image display device. (This is called the present invention [3])
(4) In the above (3), the image display device is an in-vehicle head-up display. (This is called the present invention [4])
(5) In the above (3), a television camera having the aerial image and the observation area within the camera field of view is installed on the back side of the reflective mirror, and the back side is other than the opening of the television camera. An image display device, wherein the image display device is a line-of-sight videophone display which is covered with a light shielding material. (This is called the present invention [5])
(6) In the above (1) to (5), an image display device that forms a primary image on a main plane incident side of the incident side lens, a liquid crystal panel, and a backlight that illuminates the liquid crystal back surface of the liquid crystal panel; An image display device characterized by comprising: (This is called the present invention [6])

  According to the present invention, the size of the spatial imaging iris surface and the observation area can be adjusted in accordance with the purpose of use of the display, and an image display floating in the air can be obtained. An image display device capable of exhibiting a large low power consumption effect in applications such as HUDs and videophones is realized. In addition, according to the present invention, the line of sight of callers in videophone applications can coincide with each other, and there is also an effect that it is possible to eliminate a sense of incongruity due to line-of-sight mismatch that could not be resolved conventionally.

It is the schematic which shows the 1st example of this invention. It is explanatory drawing which shows the evaluation method of the low power consumption effect by this invention. It is the schematic which shows the 2nd example of this invention. It is the schematic which shows the 3rd example of this invention. It is the schematic which shows the 4th example of this invention. It is the schematic which shows the 5th example of this invention.

  FIG. 1 is a schematic diagram showing a first example of the present invention. This 1st example is an example of the form for implementing this invention [1] and [3] (this invention [1] subordinate part of this invention [3]).

As shown in FIG. 1, in the first example, _one of the two lens groups (one lens group) having one or a plurality of lenses and the combined focal length is the focal length f ₁ is used as the incident side lens 1. (Including a plurality of lenses, the same applies hereinafter) The other (another lens group) is set as an output side lens 2 (including a plurality of lenses, the same applies hereinafter) , and the incident side lens 1 and the output side are provided. The distance between the main planes 1A and 2A of the lens 2 was set to f ₁ which is the most preferable value within f ₁ ± 20%. Here, _{"f 1} ± 20% or less" means "0.8f ₁ range of ～1.2F _1", and, when the 20% variable reduction to alpha% and (α ≧ 0), " “Within f ₁ ± α%” means “within the range of (1−α / 100) f ₁ to (1 + α / 100) f ₁ ”. In the present invention [1], the distance between the main planes 1A and 2A of the entrance side lens 1 and the exit side lens 2 is preferably within f ₁ ± 10%, and more preferably within f ₁ ± 5%.

Then, an image display device 6 that forms the primary image 3 is installed on the incident side of the main plane 1A of the incident side lens 1, and position information of the primary image 3 is converted into angle information by the incident side lens 1. did. In the first example, the imaging position of the primary image 3, the distance to the main plane 1A is the position of the entrance to within 0.2F _1.

Then, convert the main plane 2A of the exit lens 2, by setting the front focal surface 8A of the reflective mirror 8 of the focal length f _2, the angle information is the conversion output information of the incident-side lens 1 in the position information Then, a secondary image that is a similar image of the primary image 3 is formed on the rear focal plane portion 8B in the air on the emission side of the reflective mirror 8 (specifically, the tangent plane at the mirror center position of the reflective mirror 8). 9 is formed, and an infinitely triangular observation region 20 is formed on the exit side of the secondary image 9. Incidentally, the “infinity triangle” referred to here is a triangle whose one side is located at infinity.

In the present invention, the “front focal plane portion” and the “rear focal plane portion” are ranges in which the distances to the front focal plane and the rear focal plane (referred to as “surface area distance”) are within 0 ± 0.5 f ₂ , respectively. Means inside. The surface area distance is preferably within 0 ± 0.3 f ₂ , more preferably within 0 ± 0.1 f ₂ . Here, in “±”, “+” is one of the incident side and the outgoing side, and “−” is the other.

  In the first example, the front focal plane portion 8A has a distance to the front focal plane of 0 (matches the front focal plane), and the rear focal plane portion 8B has a distance to the rear focal plane of 0 (matches the rear focal plane). did.

In the first example, the image display device 6 includes a projector 4 that is a light source of the primary image 3 and a diffusion film 5 that is an imaging medium of the primary image 3. The projector 4 forms incident light as a primary image 3 on the incident surface of the diffusion film 5, and the diffusion film 5 converts the incident light of the primary image into an angle of diffusion angle = ± 15 ° (= ± θ ₁ ). Diffuses and emits uniformly within the range. As the entrance side lens 1 and the exit side lens 2, lenses having a diameter = 10 cm, a focal length f ₁ = 10 cm, and an F number = 1 were used. The incident side lens 1 picks up all the uniform diffused light with the diffusion angle = ± 15 ° from the primary image 3 and emits parallel light in which the position information is converted into angle information. Here, “parallel” in the case of “parallel light” is not only geometrically parallel (true parallel), but also two straight lines intersect in the same plane and the acute angle side crossing angle is within 10 °. It is a concept including a state (quasi-parallel).

The reflective mirror 8 of the focal length f _2, using the optical element of transparent optical material and domes according to the present invention [3]. The term “transparent” in the present invention [3] means that the transmittance is 4 to 96%. This transmittance is preferably 4 to 70%. Further, the reflectance is reflectance = 100 (%) − transmittance (%) if the absorptance is ignored.

In the first example, an acrylic hemispherical dome (hereinafter also referred to as “acrylic hemispherical dome 8”) having transmittance = 50% and a diameter (2r) = 1.5 m is used as an example of the optical element according to the present invention [3]. It was. The focal length _{f 2} of the acrylic hemisphere dome 8 becomes _{f 2 = 2r / 4 = 37.5cm} .

Therefore, as shown in FIG. 1, the front focal plane portion 8A of the acrylic hemispherical dome 8 (in the first example, the focal length f ₂ = 37.5 cm away from the tangential plane at the dome center position of the acrylic hemispherical dome 8 on the incident side. When the exit side lens 2 (focal length f ₁ = 10 cm) is installed on the plane, the position information that is the conversion output information of the entrance side lens 1 is converted into angle information by the exit side lens 2, and the acrylic hemispheric dome The rear focal plane 8B in the air on the exit side of the acrylic hemispherical dome 8 from 8 (in the first example, a plane separated by a focal length f ₂ = 37.5 cm from the tangential plane at the dome center position of the acrylic hemispherical dome 8 to the exit side. As a similar image of the primary image 3, a secondary image 9 (hereinafter also referred to as an aerial image 9) having an enlargement magnification = f ₂ / f ₁ with respect to the primary image 3 is formed.

Of the two ends of the aerial image 9, the chief ray 10 of the light applied to the image formation at one end and the chief ray 11 of the light applied to the image formation of the other end are in the front focal plane portion 8 </ b> A of the acrylic hemispherical dome 8. Light emitted from the same point and having the principal rays 10 and 11 as diffusion centers is reflected by the reflection areas 13 and 14 of the acrylic hemispherical dome 8. After being reflected, the chief rays 10 and 11 are parallel to each other. The light having the principal rays 10 and 11 after being reflected as the diffusion center is diffused at the collection angle θ ₂ with the principal rays 10 and 11 being the diffusion centers. Therefore, the region where the two systems of light diffusing at the converging angle θ ₂ with the _two principal rays 10 and 11 forming parallel light as the diffusion centers can observe the entire aerial image 9. In the first example, an infinitely triangular observation region 20 as shown in FIG. 1 is formed.

  Therefore, in the first example, as shown in FIG. 1, the observer can clearly see the entire aerial image 9 only when his / her eyes are within the observation region 20 of the infinity triangle type. Otherwise, the entire aerial image 9 cannot be seen.

  In other words, the image display device of the first example is an aerial imaging type HUD that realizes low power consumption by limiting the visible region, for example, an in-vehicle HUD according to the present invention [4].

Here, the evaluation method of the low power consumption effect (energy saving effect) by this invention is demonstrated using FIG. In FIG. 2, θ is an angle corresponding to the light collection angle θ ₂ of the aerial image 9 in FIG. Note that the condensing angle is also called an imaging angle.

A general display such as an LCD performs complete diffusion (evenly diffusing in all directions from the screen), so that the diffusion solid angle is an area S ₁ (S ₁ = 2πr ² ) of a hemisphere (large circle radius r) r ^2. 2π divided by. On the other hand, in the aerial image of the light collection angle θ according to the present invention, the diffusion range is limited to the right cone region of the apex angle θ, so that the diffusion solid angle is the apex at the center of the great circle of the hemisphere. An area S ₂ (S ₂ = π [rθ] ² ≈π [r · tan θ] ² ) of the overlapping portion of the right cone with apex angle θ and height r exceeding the hemispherical surface is divided by r ^{2. 2} θ. Here, the approximation “≈” indicates that the curved surface is approximated by a plane.

Therefore, the energy saving effect is S ₂ / S ₁ = (1/2) tan ² θ.

Here, considering a HUD that emphasizes see-through performance, a transparent HUD like glass is ideal. Therefore, even when the reflectivity is 4%, to achieve the same brightness as the LCD with the same power, (1/2) tan ² θ = 0.04, so θ = 15.8 °.

Therefore, in order to provide a vehicle-mounted HUD with a small display and a bright display in which the front is bright, it is sufficient to design with a light collection angle θ ₂ ≦ 15.8 ° in the first example (FIG. 1).

In the first example (FIG. 1), as described above, θ ₁ = 15 °, f ₁ = 10 cm, and f ₂ = 37.5 cm, and these values are processed according to the Etendue conservation law, f ₁ θ ₁ = f ₂ theta _2, are substituted into a relational equation, and θ ₂ = 4 °. Therefore, (1/2) tan ² θ ₂ = 1/409. In the present invention [1], when the reflectance of the reflective mirror 8 is 100% (transmittance = 0%) (out of the range of the present invention [3]), this is 1 An image with the same brightness can be seen with the power of / 409.

  In the case of the present invention [4] in which the present invention [3] is an in-vehicle HUD, the transmittance of the reflective mirror 8 is changed to 0% of the first example, and the upper limit of transparency (transmittance = 4 to 96%) is used. When it is 96%, the reflectance is 4%, so the energy-saving effect falls to 1/25 compared to the case where the reflectance of the reflective mirror 8 is 100%. An image with the same brightness could be seen with 1 / 16.36 power, realizing ultra-low power consumption.

  By the way, the observer of the aerial image 9 may want to observe the aerial image 9 closer to his eyes. In this case, the observation region 20 of FIG. State). In this further near vision state, there is no particular problem even if the observation region 20 has a shape other than the infinite triangle shape. This further near vision state can be easily realized by the present invention [2].

  3 and 4 are schematic views showing a second example and a third example of the present invention, respectively. In the second example (FIG. 3), in the present invention [2] and [3] (the present invention [2] dependent part of the present invention [3]), the observation region 20 is an infinite pentagon type. The third example (FIG. 4) is an example for implementing the case where the observation region 20 is a diamond type in the present invention [2] and [3].

The second example (FIG. 3) and the third example (FIG. 4) are optical systems in which the incident side lens 1, the emission side lens 2 and the image display device 6 are combined as shown in FIG. (Hereinafter referred to as the primary optical system), the main plane 2A of the exit-side lens 2 is located behind the front focal plane 8A of the acrylic hemispheric dome 8 (upstream side of the light path), and the dome center position of the acrylic hemispheric dome 8 the distance to the tangent plane at is greater distance a than f ₂ so as to be positioned in a plane, to move, than Te, the exit side of the aerial image 9, more air than in the infinity triangular An observation region of an infinite pentagonal type (second example) or a diamond type (third example) approaching the image 9 was formed, and the rest was the same as the first example. Here, the “infinity pentagon” means a pentagon whose one side is located at infinity, and “diamond” means an unequal square.

  As described above, in the present invention, by changing the primary optical system mechanically, a change from FIG. 1 (first example) to FIG. 3 (second example) and FIG. 4 (third example) is possible. is there.

  In the second example (FIG. 3), as compared with the first example (FIG. 1), the principal rays 10 and 11 passing through both ends of the aerial image 9 are the same points at positions farther from the front focal plane portion 8A of the acrylic hemispherical dome 8. Therefore, the light does not become parallel light as in FIG.

  Thereby, in the observation region 20 in FIG. 3, the vertex closest to the aerial image 9 can be made closer to the aerial image 9 than in the case of the infinity triangle type in FIG. In FIG. 3, since the observation region continues to infinity, an infinite pentagonal observation region 20 (hereinafter also referred to as an infinity pentagonal viewing region) that allows the aerial image 9 to be seen even when separated indefinitely is formed. Shows the case. This infinite pentagonal viewing area can form the widest observation area in which the range in the depth direction in which the aerial image 9 can be seen extends from relatively close to infinity.

The formation condition of this infinitely far pentagonal viewing zone is known to be “spatial imaging iris plane size> aerial image size” from the research results of the present inventors. When this condition is expressed by an equation, “(b / a) d ₂ > (f ₂ / f ₁ ) d ₁ .. [Equation 1]”. Here, a is the distance from the tangential plane (hereinafter referred to as the reference plane) at the dome center position of the acrylic hemispherical dome 8 to the main plane 2A of the exit side lens 2, and b passes through both ends of the aerial image 9 from the reference plane. The distance to the point where chief rays 10 and 11 converge and intersect, d ₁ is the size of primary image 3, d ₂ is the diameter of exit side lens 2 (d ₁ = d ₂ only when F number = 1) In general, d ₁ ≠ d ₂ ), f ₁ is the focal length of the entrance-side lens 1 (= focal length of the exit-side lens 2), and f ₂ is the focal length of the acrylic hemispherical dome 8.

Thereby, a variable viewing zone system by design and mechanism is possible. Note that the magnification f ₂ / f _{1 of} the aerial image 9 and the image formation position of the aerial image 9 (a position away from the reference plane by a distance f ₂ , see FIGS. 1, 3, and 4) are not changed. Independent control of the shape of the region 20 is possible. Further, since the condensing angle θ ₂ is not changed, it has an advantage that the energy saving effect is not affected.

  Compared to the second example (FIG. 3), the third example (FIG. 4) moves the primary optical system further rearward to set the distance a from the main plane 2A of the exit side lens 2 to the acrylic hemispherical dome 8 as the first. From the same point at a position farther than the front focal plane 8A of the acrylic hemispherical dome 8, the principal rays 10 and 11 passing through both ends of the aerial image 9 are larger than those in the two examples (in FIG. 3). Since they are out, they converge and intersect at a position closer to the aerial image 9 than in the second example (FIG. 3).

Thereby, in the observation area 20 in FIG. 4, the vertex closest to the aerial image 9 can be brought closer to the aerial image 9 than in the infinity pentagonal viewing area in FIG. 3. In this case, as shown in FIG. 4, the observation region 20 becomes a diamond shape, and does not continue to infinity, but disappears in the middle. Therefore, the entire aerial image 9 can be seen from a position very close to the aerial image 9, but cannot be seen if it is too far away. As a result of the present inventors' research, it has been found that the formation condition of the diamond-shaped observation region 20 is “aerial imaging iris surface size <aerial image size”. In terms of an equation, “(b / a) d ₂ <(f ₂ / f ₁ ) d ₁ .. [Equation 2]”. Here, a, b, d ₁ , d ₂ , f ₁ and f ₂ are synonymous with those in [Formula 1]. By making it possible to switch between the third example and the second example, a viewing zone variable system with a wider application range by design and mechanism is possible.

  Next, the present invention [5] will be described. FIG. 5 is a schematic view showing a fourth example of the present invention. This 4th example is an example of the form for implementing this invention [1] subordinate part of this invention [3] in this invention [5].

  As shown in FIG. 5, in the fourth example, in the first example (FIG. 1), a television camera 30 having the aerial image 9 and the observation region 20 in the camera field of view is installed on the back side of the acrylic hemispherical dome 8. The back side is covered with a light shielding material 31 except for the opening of the TV camera 30. As the light shielding material 31, black coating, black light absorbing paper, black velvet, black sponge, black micro triangular pyramid array, black micro quadrangular pyramid array, black micro hexagonal pyramid array and the like can be preferably used.

  Thus, the observer always looks toward the television camera 30 when viewing the aerial image 9. Accordingly, at least two image display devices of the fourth example are prepared, and one of the two (referred to as device A) and the other (referred to as device B) are connected to the television camera 30 of the device A. The photographed image is projected from the projector 4 of the apparatus B to become an aerial image 9 on the apparatus B side, and the photographed image of the television camera 30 of the apparatus B is projected from the projector 4 of the apparatus A to the aerial image 9 on the apparatus A side. By connecting each other, the observer on the device B side (referred to as the caller B), which becomes a part of the aerial image 9 on the device A side, and a part of the aerial image 9 on the device B side are connected. The observers on the device A side (referred to as caller A) inevitably match each other's line of sight.

  Thus, the image display device according to the present invention [5] can be a line-of-sight videophone display where the callers A and B can talk with each other while looking at each other's eyes.

  Next, the present invention [6] will be described.

A first example (FIG. 1), a second example (FIG. 3), a third example (FIG. 4), and a fourth example (FIG. 5) of an image display device according to any one of the present invention [1] to [5] , F ₁ <f ₂ , the primary image is imaged on the diffusion film, and then the image is magnified f ₂ / f ₁ times to form an image in the air. In general, the primary image has a small size and is a high-resolution image. However, if the light of the high-resolution image is diffused by the diffusion film, the resolution of the image is lowered due to the inevitable blur of the diffusion film. End up. Furthermore, since the fine brightness variation on the surface of the diffusion film is enlarged by f ₂ / f ₁ times to form an image in the air, the rough brightness variation is superimposed on the aerial image (secondary image), and the scintillation A so-called noise occurs. This degrades the image quality.

  In order to solve this problem, the primary image is not formed on the diffusion film, but the primary image is displayed on the liquid crystal panel and the back of the liquid crystal panel is illuminated according to the present invention [6]. A method of realizing optical characteristics with a light is preferable. In this case, since the diffusion film does not intervene between the liquid crystal panel display image and the aerial image formation, the above-mentioned problems such as the reduction in resolution and occurrence of scintillation can be solved.

  FIG. 6 shows a fifth example as an example of the present invention [6], and the configuration thereof includes a backlight 22 (for example, an LED lamp optical system) instead of the projector 4 in the first example (FIG. 1). The liquid crystal panel 21 whose back surface is illuminated by the backlight 22 is additionally provided after the diffusion film 5 (outgoing side), and has the same configuration as the first example except for these changes.

  Note that the LED lamp optical system mentioned as a specific example of the backlight 22 has a function of an optical homogenizer in order to realize uniform space irradiation. There are two typical configurations. The first method is a method in which an optically uniform surface formed by an LED chip and a light pipe or rod-like integrator is enlarged and imaged on the diffusion film 5 on the back surface of the liquid crystal panel by a projection lens system, and spatially uniform irradiation is performed. The system is an optical homogenizer system using an LED chip, a condensing lamp reflector, a lens system, a two-eye optical element, and an optical system for integration on the back of the liquid crystal panel.

  In the present invention [6], as in the fifth example, the backlight 22 has a diffusion characteristic similar to that used in the first example (diffuses incident light in a specific incident angle range into a specific diffused output angle range). From the viewpoint of improving the light utilization efficiency, it is preferable to illuminate the liquid crystal back surface of the liquid crystal panel 21 through the diffusion film 5 having the diffusion characteristic to be emitted.

DESCRIPTION OF SYMBOLS 1 Incident side lens 1A Main plane 2 (incident side lens) Outgoing side lens 2A Main plane 3 (outgoing side lens) 3 Primary image 4 Projector 5 Diffusion film 6 Image display device 8 Reflective mirror (for example, acrylic hemisphere dome)
8A Front focal plane part 8B (of the reflective mirror 8) Rear focal plane part 9 (of the reflective mirror 8) Secondary image (aerial image)
10 chief ray 11 applied to image formation at one end of aerial image 9 chief ray 12 applied to image formation at the other end of aerial image 9 optical axis 13 of projector (light having chief ray 10 Reflective area 14 (Reflected area 20 of light having principal ray 11) Observation region (Infinity triangle type in the present invention [1], pentagonal type or diamond type in infinity in the present invention [2])
21 Liquid crystal panel 22 Backlight 30 TV camera 31 Shading material

Claims (6)

One of the two lens groups consisting of one or a plurality of lenses and having a combined focal length of the focal length f ₁ is used as an incident side lens, and the other is used as an output side lens. The distance between the primary images is set within f ₁ ± 20%, and an image display device that forms a primary image on the main plane incidence side of the incident side lens is installed, and the position information of the primary image is converted into angle information. to the main plane of the exit lens, by setting the front focal surface of the reflective mirror of focal length f _2, and converts the angle information is converted output information of the exit lens to the position information, the reflective A secondary image, which is a similar image of the primary image, is formed on the rear focal plane in the air on the exit side of the mirror, and an infinite triangle type observation region is formed on the exit side of the secondary image. Image display device characterized by having a configuration of   2. The main plane of the exit lens is displaced backward from the front focal plane portion of the reflective mirror, with the relative positional relationship of the entrance lens, the exit lens, and the image display device unchanged. Thus, an observation region of an infinite pentagonal type or a diamond type that is closer to the secondary image than that of the infinite triangle type is formed on the emission side of the secondary image. An image display device.   3. The image display device according to claim 1, wherein the reflective mirror is made of a transparent optical material and a dome-shaped optical element.   The image display device according to claim 3, wherein the image display device is an in-vehicle head-up display.   4. The television camera having the aerial image and the observation region in the camera field of view is installed on the back side of the reflective mirror according to claim 3, and the back side is covered with a light shielding material except for the opening of the television camera. The image display device is a line-of-sight videophone display.   6. The image display device for forming a primary image on a main plane incident side of the incident side lens according to claim 1 comprises a liquid crystal panel and a backlight for illuminating the liquid crystal back surface of the liquid crystal panel. An image display device.

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