JP2008042287A - Eye front wearing display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device for controlling the angle of diffusion (irradiation range) of a light beam made to exit from a light source, and for irradiating the irradiation range with averaged light intensity. <P>SOLUTION: The display device is provided with: a light source 1; a display element 5 for generating an image, and for illuminating a generated image with a luminous flux made to exit from the light source; and an optical element 3. The optical element is provided with a rear face 3a on which the luminous flux from the light source is made incident, a side face 3c from which a portion of the luminous flux made incident form the rear face is reflected and a front face 3b through which the luminous flux made incident from the rear face including the luminous flux reflected from the side face is refracted or straightly advances and exits to the display elements. The display element is arranged so that the peripheral region of the display element can be illuminated with the luminous flux components made incident from the rear face of the optical element, reflected from the side face and exiting from the front face together with the luminous flux components made incident from the rear face of the optical element and directly exiting from the front face. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an information device that can be used in an environment other than a desktop, such as a wearable computer that is worn around the body via a waist belt or a jewelry, or a communication device such as a mobile phone that can be carried in a knapsack or a pocket. In particular, the present invention relates to a display device for mounting an anterior eye suitable for being placed in front of an eye by a mounting mechanism.

  As a display for an information device that is worn on the body, a display that is worn on the head is the mainstream. For example, a display that can increase the viewing angle while satisfying the optical performance while the size is small is disclosed (for example, see Patent Document 1). FIG. 4 is a diagram showing a display device mounted on the observer's head. In the display, the image display light L emitted from the display device H is reflected by the reflecting surface 11a of the first combiner 11 constituted by a half mirror or the like, and then the second combiner 12 constituted by a half mirror or the like. The light is reflected by the reflecting surface 12a and then transmitted through the first combiner 11 to be guided to the eye E of the observer. Thereby, the observer can visually recognize the virtual image of the observation object, and can also visually recognize the front entity by the light transmitted through the first combiner 11 and the second combiner 12.

As the display device H that emits the image display light L, for example, as illustrated in FIGS. 5 and 6, a light emitting diode 51 that emits light forward, a microlens 53 that is disposed on an emission surface of the light emitting diode, A display device 50 including a transmissive liquid crystal display panel 55 that generates an image is used. FIG. 5 is a diagram illustrating a schematic configuration of the display device 50. FIG. 6 is an enlarged view of the display device shown in FIG. In such a display device 50, the light beam emitted from the light emitting diode 51 is refracted by the microlens 53 having light convergence in the vertical and horizontal directions, or transmitted through the microlens 53, thereby diffusing the light. The (irradiation range M) is controlled and emitted from the transmissive liquid crystal display panel 55.
JP 2001-188194 A

  FIG. 7 is a diagram showing an irradiation light intensity distribution by the light flux from the light emitting diode 51 with respect to the transmissive liquid crystal panel 55 described above. In FIG. 7, the X axis indicates the position of the transmissive liquid crystal display panel 55, and the Y axis indicates the irradiation light intensity. An intersection point O between the X axis and the Y axis is an intersection point between the optical axis (center direction) of the microlens and the transmissive liquid crystal display panel 55. As shown in FIG. 7, since the light beam irradiated on the transmissive liquid crystal display panel 55 tends to be condensed in the center (near the optical axis extension direction) by the microlens, the irradiation light intensity distribution is uniform. Don't be. For this reason, uneven brightness occurs in the virtual image formed by the transmissive liquid crystal display panel 55.

  That is, the light intensity emitted from the light emitting diode 51 is strong at the central portion (optical axis) L1, and the light intensity becomes weaker toward the peripheral portions L2 and L3. Therefore, the irradiation range M is controlled by the microlens 53. Then, the brightness such that the central portion of the irradiation range M serving as the central region of the transmissive liquid crystal display panel 55 becomes too bright or the peripheral portion of the irradiation range M serving as the peripheral region of the transmissive liquid crystal display panel 55 becomes too dark. It has resulted in a distribution trend.

  Therefore, an object of the present invention is to provide a display device that can irradiate an irradiation range with a uniform light intensity by controlling light diffusion (irradiation range) of a light beam emitted from a light source.

  In order to solve the above problems, a display device of the present invention includes a light source having a light irradiation surface, a display element that generates an image and is illuminated by a light beam emitted from the light source, The display device includes an optical element that is disposed on the light irradiation surface and guides the light beam emitted from the light source to the display element. The optical element includes a rear surface on which the light beam from the light source is incident and a light beam incident from the rear surface. It has a side surface that reflects part of the light, and a front surface that includes the light beam reflected from the side surface and that is incident on the rear surface. The display element is incident on the rear surface of the optical element and reflected on the side surface. Then, the light beam component emitted from the front surface is arranged so as to illuminate the peripheral region of the display element together with the light beam component emitted from the rear surface of the optical element and directly emitted from the front surface.

Here, the light irradiation surface of the light source may be a flat surface or a curved surface, but it is desirable that the light can be emitted without loss toward the front surface of the optical element disposed on the light irradiation surface.
The display element may be a transmissive display element in which illumination light for illuminating an image is transmitted through the display element, or a reflective display element in which the illumination light is reflected by the display element.

According to the display device of the present invention, the light beam irradiated from the light irradiation surface of the light source enters from the rear surface of the optical element, then exits from the front surface of the optical element, and further irradiates the display element, whereby a virtual image is formed. Guided by the observer's eyes. As a result, the observer visually recognizes the virtual image to be observed.
At this time, the optical element reflects a part of the light beam emitted from the light source on the side surface (total reflection), thereby controlling the light diffusion angle (irradiation range) and irradiating the display element. . Therefore, by setting the shape of the optical element and the arrangement of the display element so that the luminous flux component reflected from the side surface is irradiated to the peripheral area of the display element, the light intensity that irradiates the peripheral area of the display element is increased. .

  According to the present invention, since the luminous flux that irradiates the peripheral area of the display element is increased by the luminous flux component reflected from the side surface of the optical element, the luminance of the peripheral area of the display element can be brought close to the luminance of the central area. The luminance distribution of the elements can be averaged.

(Means and effects for solving other problems)
In the above invention, the optical element has a front side larger than the rear side and a cone having rotational symmetry about the optical axis, which is a light beam component that travels straight from the rear surface and exits from the front surface. It may be trapezoidal or pyramidal trapezoidal. Specifically, it is adapted to the shape of the display element (circular or square), and in addition to the truncated cone shape, a rectangular pyramid shape (optical axis cross section is square or rectangular) is preferable.
According to this, since the optical path can be easily designed according to the size and arrangement of the display element, the brightness of the peripheral area of the display element can be easily adjusted by setting the angle (θ) of the side surface with respect to the optical axis. become.

In the above invention, a reflective film may be formed on the side surface of the optical element. Here, the reflective film is preferably a metal film such as silver or aluminum.
According to this, by forming the reflective film on the side surface of the optical element, it is possible to effectively eliminate the light loss due to leakage from the side surface to the outside and to effectively use the reflected light.

Moreover, in the said invention, a light source may consist of a light emitting diode, and you may make it contact so that the rear surface of an optical element may cover the light irradiation surface of a light emitting diode.
According to this, almost all the irradiation light from the light emitting diode can be guided to the optical element by making a contact so that the rear surface of the optical element covers the light irradiation surface of the light emitting diode.

In the above invention, the display element device may be arranged in front of the user's eyes by a mounting mechanism.
When used for mounting in front of the eye, the size of the external dimension (corresponding to the irradiation range M) of the display element is practically limited. Specifically, the outer dimensions (diameter in the case of a circle, side length in the case of a square or the like) are preferably 1 mm or more and 100 mm or less.
As a result, a display device suitable for a wearable computer can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it goes without saying that various aspects are included without departing from the spirit of the present invention.

  FIG. 4 is a diagram illustrating a schematic configuration of a display device according to an embodiment. The display includes a display device H and an eyepiece optical system 30 that are covered with a casing (not shown). The indicator is attached to the body of the observer, such as the head and arms, or a helmet or glasses attached to the body via a headset, belt, band, clip, etc., or a mobile phone, watch, etc. It is mounted on various portable devices and used while being held in the hand.

FIG. 1 is a diagram showing a schematic configuration of a display device according to an embodiment of the present invention. FIG. 2 is an enlarged view of the display device shown in FIG.
The display device 10 is disposed above the eyepiece optical system 30, has a light emitting diode 1 that emits light from a light irradiation surface, and a truncated cone shape that has an optical axis L 1 as a rotation center. The optical element 3 is disposed so as to be in contact with the light irradiation surface, and the transmissive liquid crystal display panel 5 that generates an image.

  The light emitting diode 1 emits light. Here, the luminous flux emitted from the light emitting diode 1 is generally designed so that the light emission intensity is strong in the central direction (normal direction of the light emitting diode irradiation surface) and the light emission intensity becomes weaker in the peripheral direction. . Therefore, in the light beam emitted from the light emitting diode 1, the light irradiation intensity of the light beam L1 is strong, and the light irradiation intensity of the light beam L2, the light beam L3, and the light beam decreases in order.

As described above, the optical element 3 has a truncated cone shape, and includes a rear surface 3a on which the light beam from the light emitting diode 1 is incident, a front surface 3b that emits the light beam to the transmissive liquid crystal display panel 5, and a side surface 3c. The side surface 3c is disposed at an angle (θ) that reflects a part of the light beam incident from the rear surface 3a and emits the reflected light beam from the front surface 3b with respect to the optical axis direction L1.
The rear surface 3a and the front surface 3b have a planar shape, and the rear surface 3a and the front surface 3b are parallel to each other.

  Here, a mechanism in which the display device 10 emits the image display light L to the eyepiece optical system 30 will be described. First, the light emitting diode 1 emits light beams L1, L2, and L3 having different light emission intensities toward the optical element 3. Next, the light beams L 1, L 2, L 3 from the light emitting diode 1 to the optical element 3 are incident on the rear surface 3 a of the optical element 3. At this time, since the light beam L1 travels straight on the optical axis of the optical element 3, it travels straight while maintaining a direction perpendicular to the transmissive liquid crystal display panel 5, and is emitted from the front surface 3b of the optical element 3. The light beam L2 is refracted for the first time at the rear surface 3a of the optical element 3 and is refracted for the second time from the front surface 3b. The light L3 is first refracted by the rear surface 3a of the optical element 3, then reflected by the side surface 3c, and further emitted from the rear surface 3b with second refraction.

  Here, the angle (θ) of the side surface 3c is designed so that the irradiation range of the transmissive liquid crystal display panel 5 is irradiated with uniform light intensity. That is, the light beam L 1 having a high light intensity irradiates the central portion of the transmissive liquid crystal display panel 5. On the other hand, the light beam L2 having a slightly weak intensity irradiates the peripheral portion of the transmissive liquid crystal display panel 5. Therefore, the light beam L3 having a weaker intensity is irradiated on the peripheral portion of the transmissive liquid crystal display panel 5. Therefore, as shown in FIG. 3, the light beams L 1, L 2, and L 3 are emitted with the irradiation light intensity averaged by the optical element 3 to the transmissive liquid crystal display panel 5. In FIG. 3, the X axis indicates the position of the transmissive liquid crystal display panel 5, and the Y axis indicates the irradiation light intensity. An intersection point O between the X axis and the Y axis is an intersection point between the optical axis of the optical element 3 and the transmissive liquid crystal display panel 5.

  Thereafter, the light beams L1, L2, and L3 reaching the transmissive liquid crystal display panel 5 become image display light L and are emitted toward the first optical element 11 described later. In this way, the display device 10 emits the image display light L toward the first optical element 11.

  The eyepiece optical system 30 includes a first optical element 11 disposed in front of the observer's eye E, and a second optical element 12 disposed in front of the first optical element 11 via a space 40. The 1st optical element 11 and the 2nd optical element 12 are combiners comprised by a half mirror and a hologram element, respectively, for example. Therefore, the first optical element 11 and the second optical element 12 have a beam splitting function that reflects and transmits incident light.

  Here, the surface opposite to the viewer side of the first optical element 11 is defined as a first optical path changing surface 11a, and the surface on the viewer side of the first optical element 11 is defined as a first passing surface 11b. In addition, the observer-side surface of the second optical element 12 is a second optical path changing surface 12a, and the opposite surface of the second optical element 12 on the observer side is a second passage surface 12b. A space 40 is formed between the first optical path changing surface 11a and the second optical path changing surface 12a.

  The first optical path changing surface 11a has a convex curved surface shape for diverging incident light, and the second optical path changing surface 12a has a concave curved surface shape for converging incident light. The first optical path changing surface 11a, the second optical path changing surface 12a, the first passing surface 11b, and the second passing surface 12b are, for example, “off-axis rotationally symmetric aspheric surfaces”.

The off-axis rotationally symmetric aspherical surface is represented by a surface having a center decentered from the rotationally symmetric axis of the aspherical surface in the aspherical surface specified by the shape function represented by the following mathematical formula (1) in the xyz coordinate space. Here, in Formula (1), ρ ² = x ² + y ² and c = 1 / R. The numerical formula (1) represents a spherical surface when the quadric surface coefficient K and the aspherical coefficient αi (i = 1 to n) are 0, and the radius of the spherical surface is R. Therefore, an aspherical surface means that at least one aspherical coefficient αi is not 0 in Equation (1).

  Note that the curvature c, the quadratic surface coefficient K, and the aspheric coefficient αi (i = 1 to n) defining the off-axis rotationally symmetric aspheric surface are the magnification of the virtual image to be observed with respect to the real image on the display device 10, from the display device 10. In accordance with the optical path length to the observer's eye E, etc., it is determined so that a virtual image can be clearly formed at a position far away from the observer.

  The first optical element 11 and the second optical element 12 are plate-like bodies having a uniform thickness. For example, the first optical element 11 has a uniform thickness by making the first optical path changing surface 11a and the first passing surface 11b have the same shape. On the other hand, the thickness of the second optical element 12 is also made uniform by, for example, making the second optical path changing surface 12a and the first passage surface 12b have the same shape.

  Here, a mechanism in which the eyepiece optical system 30 guides the image display light L to the observer's eye E will be described. First, the image display light L emitted from the display device 10 and reaching the first optical path changing surface 11a is reflected by the first optical path changing surface 11a so as to go toward the second optical path changing surface 12a. Further, the image display light L reaching the second optical path changing surface 12a is reflected by the second optical path changing surface 12a so as to go to the first optical path changing surface 11a. Then, the image display light L reaching the first optical element 11 passes through the first optical element 11 and is guided to the eye E of the observer. Therefore, the eyepiece optical system 30 forms the virtual image of the observation target by guiding the image display light L to the observer's eye E.

As described above, according to the display device 10, the light beam emitted from the light emitting diode 1 is incident from the rear surface 3 a of the optical element 3, is then emitted from the front surface 3 b of the optical element 3, and is further transmitted through the transmissive liquid crystal display panel. By irradiating 5, a virtual image is guided to the observer's eye E. Thereby, the observer can visually recognize the virtual image of the observation target.
At this time, the optical element 3 reflects a part of the light beam emitted from the light emitting diode 1 by the side surface 3c, thereby controlling the light diffusion angle (irradiation range) and irradiating the transmissive liquid crystal display panel 5. can do. Further, by adjusting the angle at which a part of the light beam emitted from the light emitting diode 1 is reflected by the side surface 3c, the irradiation range of the transmissive liquid crystal display panel 5 can be irradiated with uniform light emission intensity.

  The materials for forming the optical element, the first optical element, and the second optical element may be the same as or different from each other. For example, polycarbonate (PC), polymethacrylic acid (PMMA), cycloolefin, glass material, etc. Is mentioned.

Further, the rear surface 3a and the front surface 3b of the optical element may have a curved surface shape instead of the planar shape. Or you may provide a wedge in the angle of a surface.
The side surface 3c is not limited to a flat surface but may be a curved surface as long as the optical path can be adjusted so that the reflected light beam can be emitted from the front surface 3b and irradiate the peripheral region of the display element 5. Furthermore, it may be configured to reflect by an aluminum coat or the like, not by total reflection due to a difference in refractive index.

Further, a reflective liquid crystal display panel may be used in place of the transmissive liquid crystal display panel. Further, the transmissive liquid crystal display panel may be one that forms a color image by incorporating a color filter, or one that forms a monochrome image without a color filter.
The image display light may be guided to both eyes of the observer, and the second optical path changing surface may be constituted by a total reflection mirror.

  The present invention can be used for information equipment used in an environment other than a desktop.

It is a figure which shows schematic structure of the display apparatus which is one Embodiment of this invention. It is an enlarged view of the display apparatus shown in FIG. It is a figure which shows the relationship between the position of the display apparatus transmissive liquid crystal display panel of this invention, and emitted light intensity. It is a figure which shows schematic structure of the indicator which is one Embodiment. It is a figure which shows schematic structure of the conventional display apparatus. It is an enlarged view of the display apparatus shown in FIG. It is a figure which shows the relationship between the position of the transmissive liquid crystal display panel by the conventional display apparatus, and light emission intensity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting diode 3 Optical element 5 Transmission type liquid crystal display panel 10 Display apparatus 11 1st optical element 12 2nd optical element L Image display light E Eye of an observer

Claims (5)

A light source having a light irradiation surface;
A display element that generates an image and the generated image is illuminated by a light beam emitted from a light source;
A display device including an optical element disposed on a light irradiation surface of a light source and guiding a light beam emitted from the light source to the display element;
The optical element includes a rear surface on which a light beam from a light source is incident, a side surface that reflects a part of the light beam incident from the rear surface, and a light beam that is incident from the rear surface including the light beam reflected on the side surface and refracts or goes straight and exits to the display element. Has a front surface,
The display element is arranged so that the luminous flux component incident from the rear surface of the optical element and reflected from the side surface and then emitted from the front surface illuminates the peripheral area of the display element together with the luminous flux component incident from the rear surface of the optical element and emitted directly from the front surface. A display device characterized by being made. The optical element has a truncated cone shape or a truncated pyramid shape having a rotational symmetry about the optical axis that is a light beam component that is a straight beam component of a light beam that enters from the rear surface and exits from the front surface, while the front surface side is larger than the rear surface side. The display device according to claim 1, wherein: The display device according to claim 1, wherein a reflective film is formed on a side surface of the optical element. The display device for mounting on the eye according to claim 1, wherein the light source comprises a light emitting diode, and the rear surface of the optical element is in contact with the light irradiation surface of the light emitting diode. The display device according to claim 1, wherein the display device is arranged in front of the user's eyes by a mounting mechanism.