JP3632392B2 - Retina display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a retinal display device, and more particularly to a small and lightweight retinal display device using a laser diode.
[0002]
[Prior art]
Various types of retina display devices have been proposed in the past, and head-up displays and head-mounted displays are examples of devices capable of viewing images (with a see-through function) without blocking the outside world. Although this type of device has been promoted to be downsized, a sufficient device has not yet been obtained. One of the obstacles to miniaturization is the display element portion. In order to meet the requirement of simultaneously viewing images while looking at the outside world, it is necessary to give high luminance to the display element that projects the images. Therefore, it has been difficult to reduce the size of the display element.
[0003]
Under such circumstances, a small and low power consumption display device using a laser diode has been proposed. For example, Japanese Patent Application Laid-Open No. 62-5288 discloses a display device that is reduced in size and has improved wearability. This apparatus is configured to reproduce a desired image by scanning a Lippmann hologram with a reference light beam. Therefore, it is advantageous in that a large space such as a large-diameter optical lens or a cathode ray tube is not required.
[0004]
[Problems to be solved by the invention]
However, in the case of the display device described above, since the energy with which object light reaches the photosensitive material is small when producing a hologram, a hologram with high diffraction efficiency cannot be obtained. Therefore, there is a problem that the laser used at the time of reproduction requires a high output.
[0005]
Accordingly, an object of the present invention is to provide a small and lightweight retinal display device using a low-power laser diode.
[0006]
[Means for Solving the Problems]
The object is to provide a laser diode that generates image information light, a collimator that converts the image information light into a parallel light beam, a micromirror device that two-dimensionally scans the image information light of the parallel light beam from the collimator, and This is achieved by a retinal display device having a hologram irradiated with two-dimensional image information light from a micromirror device and a lens on which the hologram is formed.
[0007]
As the laser diode used here, a low-power laser diode is sufficient. The hologram formed on the lens has a function of converting coherent light emitted from the laser diode into incoherent light.
[0008]
This hologram manufacturing method divides light from a laser into two light beams, irradiates a photopolymer formed on a spectacle lens through a first diaphragm with one of the divided light beams as a reference light, This is performed by irradiating the above-mentioned photopolymer with the other divided light beam as object light through the second diaphragm and the diffusion plate. Here, a He—Ne laser is used as the laser.
[0009]
In this way, according to the present invention, a hologram having a relatively large diffraction efficiency can be produced. By using this hologram in this apparatus, the laser diode used during reproduction is made to have a low output. The advantage of using a low-power laser diode is not only low power consumption but also improved safety for human eyes. By using this type of hologram, image information light from a low-power laser diode can be scanned by a micromirror device. The laser diode and the micromirror device are ultra-compact, and the entire apparatus can be made small and light.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an embodiment of a retinal display device according to the present invention. As shown in the figure, a hologram 4 is formed on the concave surface of the spectacle lens 5. A laser diode (LD) 1, a collimator 2, and a micromirror device 3 are arranged in a frame 30 indicated by a broken line that supports the spectacle lens 5. When this apparatus is mounted, human eyes come to be positioned near the concave surface of the spectacle lens 5. In the figure, an eyeball 6 having a pupil 7, a lens 8, and a retina 9 is shown.
[0011]
An LD driving device (not shown) is connected to the LD 1, and light having image information (image information light) emitted from the LD 1 passes through the collimator 2 and becomes parallel image information light. This image information light is scanned two-dimensionally through the micromirror device 3 and becomes two-dimensional image information light. The micromirror device 3 used here is an ultra-compact mirror, which includes a single mirror with a movable mirror in one direction and a single mirror with a movable mirror in two directions. It is produced by. Here, in the case of a unidirectional movable mirror, laser light is two-dimensionally scanned using two elements. In the case of a movable mirror in two directions, laser light is two-dimensionally scanned using one element. In this way, the micromirror device 3 scans the image information light two-dimensionally. Further, after spreading the laser light with a beam expander, it may be collimated and irradiated to a DLP (manufactured by TI) to form two-dimensional image information light.
[0012]
This two-dimensionally scanned image information light is applied to the hologram 4 formed on the spectacle lens 5. The hologram 4 is for converting laser light, which is coherent light, into incoherent light after being diffracted. The two-dimensional image information light diffracted by the hologram 4 enters the eyeball 6 as incoherent light, focuses on the pupil 7 of the eye, passes through the crystalline lens 8, and forms an image on the retina 9. Thereby, the observer can recognize a two-dimensional image.
[0013]
FIG. 2 is a diagram showing another embodiment of the retinal display device according to the present invention. In this embodiment, the hologram 4 is formed on the convex surface of the spectacle lens 5. The process in which light having image information emitted from the LD 1 becomes two-dimensional image information light is the same as that in the embodiment of FIG. However, this two-dimensional image information light is incident from the end face of the spectacle lens 5 and is diffracted by the hologram 4. Therefore, the micromirror device 3 is arranged near the corner of the frame 30 as shown in the figure.
[0014]
In FIGS. 1 and 2, only the lens corresponding to one lens 5 of the two spectacle lenses is shown, but in reality, a hologram is similarly formed on the other lens (not shown). An LD, a collimator, and a micromirror device are arranged in the other frame. As a light source, a light emitting diode (LED) or an electroluminescence (EL) element can be used in addition to the LD.
[0015]
FIG. 3 shows a method for producing the hologram 4 used here. As shown in the figure, the laser 10 emits visible light, for example, a He-Ne laser having a wavelength of 632.8 nm. This laser light is split into two light beams by the beam splitter 11. One of the divided light beams 12 is bent as a reference light by a mirror 13, converted into diffused light by a spatial filter 14, and applied to a photopolymer 16 formed on a spectacle lens 15. The other divided light beam 17 is bent as object light by a mirror 18, converted into diffused light by a spatial filter 19, and converted into a parallel light beam via a collimating lens 20. The parallel light beam passes through the diaphragm 21, is converted into convergent light by the lens 22, passes through the diffusion plate 23, and is irradiated onto the above-described photopolymer 16 formed on the spectacle lens 15.
[0016]
Thus, the photopolymer 16 subjected to interference exposure with two light beams is recorded as a hologram after ultraviolet irradiation and heat treatment. Thereby, a hologram combiner having an eyepiece optical system can be obtained. The hologram obtained here has a relatively large diffraction efficiency.
[0017]
In the present invention, as described above, a hologram having a relatively large diffraction efficiency is produced, and this is used to make the laser diode used for reproduction low-powered. The advantages of using a low-power laser diode are low power consumption and improved safety for the human eye. By using this type of hologram, image information light can be scanned by a micromirror device, and the entire apparatus can be made small and light with the use of a laser diode.
[0018]
The hologram manufacturing method shown in FIG. 3 corresponds to the embodiment of FIG. 1, but the hologram according to the embodiment of FIG. 2 can also be manufactured by a method almost similar to this as shown in FIG. The difference is that, unlike the embodiment of FIG. 1, a photopolymer is formed on the convex surface of the spectacle lens, and the reference light is incident from the side surface of the spectacle lens. Hereinafter, the method shown in FIG. 4 will be described in detail.
[0019]
In FIG. 4, a laser 10 is a laser that emits visible light, and is, for example, a He—Ne laser with a wavelength of 632.8 nm. The light from the laser 10 is split into two by the beam splitter 11. The divided light beam 12 is bent as a reference light by a mirror 13 and then converted into diffused light by a spatial filter 14. Thereafter, the light is converted into parallel light by the collimator lens 25 and enters the diaphragm 26. The reference light passes through the diaphragm 26, then enters from the side surface of the spectacle lens 15, and is irradiated on the photopolymer 28 formed on the spectacle lens 15. On the other hand, another light beam 17 is bent as object light by a mirror 18, diffused by a spatial filter 19, and converted into parallel light by a collimating lens 20. Thereafter, the object light passes through the diaphragm 21, is converted into convergent light by the lens 22, and is irradiated onto the photopolymer 28 from the front surface of the eyeglass lens 15. As a result, the photopolymer 28 is subjected to interference exposure with the two light beams 12, 17, irradiated with ultraviolet rays, then subjected to heat treatment, and recorded as a hologram.
[0020]
Thus, since the hologram can be easily formed on the spectacle lens, the device according to the present invention can be easily manufactured.
[0021]
【The invention's effect】
According to the present invention, a small and lightweight retinal display device using a low-power laser diode can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a retinal display device according to the present invention.
FIG. 2 is a view showing another embodiment of the retinal display device according to the present invention.
FIG. 3 is a diagram showing a method for producing a hologram used in the present invention.
FIG. 4 is a diagram showing another method for producing a hologram used in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser diode 2 Collimator 3 Micromirror device 4 Hologram 5 Glasses lens 6 Eyeball 7 Pupil 8 Crystal 9 Retina

Claims (6)

A laser diode that generates image information light, a collimator that converts the image information light into a parallel light beam, a micromirror device that two-dimensionally scans the image information light of the parallel light beam from the collimator, and the micromirror device And a lens on which the hologram is formed, and the hologram has a function of converting coherent light into incoherent light . 2. The retinal display device according to claim 1, wherein the lens on which the hologram is formed is an eyeglass lens. The retinal display device according to claim 2, wherein the hologram is formed on a concave surface of the eyeglass lens. The retinal display device according to claim 2, wherein the hologram is formed on a convex surface of the eyeglass lens. The light from the laser is divided into two light beams, one of the divided light beams is used as a reference light to irradiate the photopolymer formed on the spectacle lens through the first diaphragm, and the other divided light beam is irradiated. A hologram is obtained by irradiating the photopolymer formed on the eyeglass lens as object light through the second diaphragm and the diffusing plate with the two light beams for interference exposure. Hologram manufacturing method for retinal display device. 6. The hologram manufacturing method for a retinal display device according to claim 5 , wherein the laser is a laser that emits visible light.

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