JP6507566B2 - Image display device and wearable image display device - Google Patents

Description

  The present invention relates to an image display device and a wearable image display device.

  For example, as shown in FIG. 7, a scanning mirror 520 comprising a light source 510 such as a semiconductor laser beam for emitting light, and a MEMS for reflecting light from the light source 510 toward the reflection mirror 530 as the above-mentioned wearable image display device. There is known a head mounted display (HMD) provided with an image display device including a reflection mirror 530 for observing the light from the scanning mirror 520 as first-order diffracted light. As one of the head mounted displays, there is provided one which can simultaneously view an image while looking at the background using the see-through property.

  Recently, in place of the reflection mirror, a reflective deflection element is used which diffracts and deflects the light from the scanning mirror 520 in a direction different from the incident direction. As a deflection element (reflection mirror), for example, as described in Patent Document 1, a volume hologram (reflection type volume hologram diffraction grating) which is compact and has a high degree of freedom in light operation is used.

Unexamined-Japanese-Patent No. 2007-094175

  However, as shown in FIG. 7, when light is incident on the deflection element (reflection mirror 530), there is a problem that the image viewed by the observer is viewed by another person by the zero-order light transmitted without being diffracted. is there. It is difficult to eliminate these zero-order lights. As a result, there is a problem that security security decreases.

  The aspect of the present invention is made in order to solve at least a part of the above-mentioned subject, and can be realized as the following modes or application examples.

  Application Example 1 The image display apparatus according to this application example is a light source and a diffraction that is disposed at a position where light from the light source is incident, and deflects at least a part of the incident light in a direction different from specular reflection. Providing an optical element, and a light reduction element disposed on the opposite side of the light source of the diffractive optical element and suppressing emission of light transmitted through the diffractive optical element without being deflected by the diffractive optical element It features.

  According to this application example, since the diffractive optical element is disposed, the direction of the light from the light source can be changed to a desired direction. Furthermore, since the light reducing element is disposed on the opposite side to the light source of the diffractive optical element, it is possible to reflect 0th-order light transmitted through the diffractive optical element in the light from the light source. Therefore, as in the case where zero-order light is transmitted to the outside, for example, it can be suppressed that another person can see an image.

  Application Example 2 In the image display device according to the application example, the diffractive optical element is preferably a volume hologram.

  According to this application example, since volume holograms are used, it is possible to diffract with relatively high efficiency.

  Application Example 3 In the image display device according to the application example, the diffractive optical element is preferably a surface relief hologram or a blazed diffraction grating.

  According to this application example, for example, in the case of using a surface relief hologram, mass productivity is excellent, and the manufacturing cost can be reduced.

  Application Example 4 In the image display device according to the application example, the light reducing element is preferably a dichroic mirror that reflects light of a predetermined wavelength.

  According to this application example, since the dichroic mirror is used as the light reduction element, it becomes possible to reflect the 0th-order light transmitted through the diffractive optical element in the light from the light source, thereby suppressing the leakage of the 0th-order light to the outside be able to. Thus, for example, it can be suppressed that another person can see the image.

  Application Example 5 In the image display device according to the application example, it is preferable that the light reducing element is a polarizing plate that suppresses transmission of light other than a predetermined polarization direction.

  According to this application example, since the polarizing plate is used as the light reducing element, it becomes possible to reflect the 0th-order light transmitted through the diffractive optical element in the light from the light source, thereby suppressing the leakage of the 0th-order light to the outside be able to. Thus, for example, it can be suppressed that another person can see the image.

  Application Example 6 In the image display device according to the application example, it is preferable that the diffractive optical element and the light reducing element be curved.

  According to this application example, since the image light can be corrected by the curvature of the diffractive optical element and the light reducing element, high resolution image light can be obtained.

  Application Example 7 In the image display device according to the application example, it is preferable that the peak wavelength contained in the light from the light source is the same wavelength as the peak wavelength of the reflectance of the dichroic mirror.

  According to this application example, since the peak wavelength included in the light of the light source and the peak wavelength of the reflectance of the dichroic mirror are the same wavelength, it is possible to suppress the light from leaking from the image display device.

  Application Example 8 A wearable image display device according to this application example includes the image display device described above.

  According to this application example, since the above-mentioned image display device is provided, it is possible to prevent another person from observing the image, and security can be improved. Furthermore, bright image light can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic perspective view which shows the whole image of the head mounted display (HMD) as a mounting | wearing type image display apparatus of 1st Embodiment. The schematic plan view which looked at the head mounted display from upper direction. FIG. 3 is an enlarged schematic view showing a configuration of an image display device of a portion A of the head mounted display shown in FIG. 2; The graph which shows the characteristic of a dichroic mirror. Schematic which shows the structure of the image display apparatus of 2nd Embodiment. The schematic diagram which shows the structure of the image display apparatus of 3rd Embodiment. The schematic diagram which shows the structure of the conventional image display apparatus.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings to be used are appropriately enlarged or reduced and displayed so that the parts to be described can be recognized.

First Embodiment
<Configuration of Wearable Image Display Device>
FIG. 1 is a schematic perspective view showing the entire image of a head mounted display (HMD) as a wearable image display device. FIG. 2 is a schematic plan view of the head mounted display as viewed from above. Hereinafter, the configuration of the head mounted display will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the head mounted display 1000 includes a main body 100 having a shape like glasses, and a controller 200 having a size that can be held by the user's hand.

  The main unit 100 and the control unit 200 are communicably connected by wire or wirelessly. In the present embodiment, the main unit 100 and the control unit 200 are communicably connected by the cable 300. Then, the main body unit 100 and the control unit 200 communicate an image signal and a control signal via the cable 300.

  The main unit 100 includes a right-eye display unit 110A and a left-eye display unit 110B. The right-eye display unit 110A includes an image forming unit 120A that forms image light of a right-eye image. The display unit for left eye 110B includes an image forming unit 120B that forms image light of the image for left eye.

  The image forming unit 120 </ b> A is housed in a temple (right side) of the glasses in the glasses-type main body unit 100. On the other hand, the image forming unit 120 </ b> B is accommodated in the temple (left side) of the glasses in the glasses-type main unit 100.

  The main body portion 100 is provided with a visual recognition portion 131A having light transparency. The visual recognition unit 131A emits the image light of the right-eye image toward the right eye of the user. Further, in the head mounted display 1000, the visual recognition unit 131A has optical transparency, and the surroundings can be visually recognized through the visual recognition unit 131A.

  Further, the main body portion 100 is provided with a visible portion 131B having light transparency. The visual recognition unit 131B emits the image light of the image for the left eye toward the left eye of the user. Further, in the head mounted display 1000, the visual recognition unit 131B has optical transparency, and the surroundings can be visually recognized through the visual recognition unit 131B.

  The control unit 200 includes an operation unit 210 and an operation button unit 220. The user performs an operation input on the operation unit 210 and the operation button unit 220 of the control unit 200, and instructs the main unit 100.

  Further, as shown in FIG. 2, in the head mounted display 1000, the light source 10, the scanning mirror 20, and the like are disposed in the frame 140 portion. In addition, although the code | symbol is attached | subjected only to the right side part of the flame | frame 140, the frame on the left side is the same.

  The light source 10 is a semiconductor laser beam, and is a laser beam obtained by multiplexing the laser beams output from the red laser beam source, the blue laser beam source, and the green laser beam source. Then, laser light of any color can be output by appropriately modulating the output from each color laser light source. Further, by modulating in conjunction with a scanning mirror 20 or the like, which will be described later, it is possible to display an image on the retina of the user's eyes.

  Further, in the frame 140, reflective diffractive optical elements 30 for displaying an image on the retina of the user's eyes are arranged corresponding to the right eye and the left eye. Note that the image display device 50 (see FIG. 3) including at least the light source 10, the scanning mirror 20, and the reflective diffractive optical element 30 is referred to. Next, the image display device 50 will be described.

<Configuration of Image Display Device>
FIG. 3 is a schematic view showing the configuration of the image display apparatus of the portion A of the head mounted display shown in FIG. 2 in an enlarged manner. FIG. 4 is a graph showing the characteristics of the dichroic mirror that constitutes the light reduction element. Hereinafter, the configuration of the image display device will be described with reference to FIGS. 3 and 4.

  As shown in FIG. 3, the image display device 50 is a light source 10, a scanning mirror 20 that reflects the light from the light source 10, and a reflection type diffraction that causes the light reflected by the scanning mirror 20 to be diffracted and displayed to the observer And an optical element 30.

  As described above, the light source 10 is outputted from the red laser light source (for example, peak wavelength is 640 nm), the blue laser light source (for example, peak wavelength is 460 nm), and the green laser light source (for example, peak wavelength is 532 nm) Laser beams are combined.

  The scanning mirror 20 is configured of, for example, a MEMS. Specifically, vibration control of the mirror is performed at a certain frequency, and miniaturization is realized.

  The reflective diffractive optical element 30 is made of a flat material, and includes a substrate 31, a deflecting element 32, and a light reducing element 33 from the light source 10 side. For example, glass, acryl, polycarbonate or the like is used as the substrate 31.

  As the deflecting element 32, a diffractive optical element may be mentioned, and among them, a volume hologram, a surface relief hologram, a blazed diffraction grating or the like can be used. When using a volume hologram, it can be diffracted with relatively high efficiency. In the case of using a surface relief hologram, mass productivity is excellent, and the manufacturing cost can be reduced.

  In the present embodiment, a volume hologram is used. The volume hologram is configured, for example, by alternately laminating low refractive index layers and high refractive index layers. The volume hologram can be formed, for example, by interference exposure.

  By using such a deflection element 32 (diffractive optical element), it is possible to change the direction of light to a direction that is not specular reflection, while it is only possible to make the light travel regular reflection with a general mirror. It becomes. In addition, the deflecting element 32 can be miniaturized with respect to a general mirror.

  As the light reduction element 33, for example, a dichroic mirror can be used. The dichroic mirror reflects zero-order transmitted light (light from which the light from the light source 10 is transmitted without being diffracted by the deflection element 32 (without changing the direction), and the image light is output to the outside of Prevent going. This can ensure security.

  In addition, the reflective diffractive optical element 30 transmits external light incident from the outside of the head mounted display 1000 so that the observer can observe the scenery (background). Specifically, the laser light of the light source 10 is narrow band, and the outside light is wide band. Therefore, it is possible to observe external light through the dichroic mirror that reflects the light source 10 wavelength.

  That is, the head mounted display 1000 of the present embodiment has see-through property, and can view an image simultaneously with the background. Next, referring to FIG. 4, an example of the spectral characteristics of the dichroic mirror will be described.

  As shown in FIG. 4, the dichroic mirror used for the head mounted display 1000 (image display device 50) has a wavelength (reflection wavelength) at which the reflectance is maximum is 460 nm for blue, 532 nm for green, and 640 nm for red The specifications are set as follows. Furthermore, at wavelengths other than the above wavelengths, the reflectance of the dichroic mirror is set to be low.

  The wavelength range W in which the dichroic mirror shown in FIG. 4 reflects the laser light is preferably set to about 5 nm to 20 nm. The spectral width of the laser light is about ± 1 nm with respect to the peak wavelength.

  By matching the peak wavelength (light source wavelength) of the laser light with the reflectance characteristic (reflection wavelength) of the dichroic mirror, it is possible to see through the background and to reflect the image light. .

  In addition, the laser light may have variations (shifts) in peak wavelengths (wavelengths at which light emission intensity is maximized). In particular, wavelength shift tends to occur when high-speed modulation is performed to increase the modulation speed. However, by using a dichroic mirror, it is possible to suppress the emission of zero-order transmitted light even when the peak wavelength is shifted.

  As described above, according to the image display device 50 and the head mounted display 1000 of the first embodiment, the following effects can be obtained.

  (1) According to the image display device 50 of the first embodiment, since the volume hologram is disposed as the deflecting element 32, the direction of the light from the light source 10 can be in the direction in which the desired direction (observer) can view It can be changed. Furthermore, since the dichroic mirror is disposed as the light reduction element 33 on the opposite side of the light source 10 of the deflection element 32, it is possible to reflect 0th-order light transmitted through the deflection element 32 out of the light from the light source 10. . Therefore, as in the case where the zero-order light passes through the reflective diffractive optical element 30, for example, it can be suppressed that the image light is seen by another person.

  (2) According to the image display device 50 of the first embodiment, the optical characteristics of the dichroic mirror as the light reducing element 33, the peak wavelength (R, G, B) of the light source 10, and the reflectance of the dichroic mirror By setting the wavelengths (R, G, B) to be equal to each other, it is possible to suppress the image light from leaking from the image display device 50 (head mounted display 1000) to the outside.

  (3) According to the head mounted display 1000 of the first embodiment, since the image display device 50 is provided, it is possible to prevent another person from observing the image light, and the head mounted display 1000 with high security. Can be provided. Furthermore, bright image light can be provided.

Second Embodiment
<Configuration of Image Display Device>
FIG. 5 is a schematic view showing the configuration of the image display device of the second embodiment. Hereinafter, the configuration of the image display device will be described with reference to FIG.

  The image display apparatus 150 according to the second embodiment differs from the image display apparatus 50 according to the first embodiment described above in the part replacing the dichroic mirror with the polarizing plate as the light reduction element 133, and the other parts are generally the same. It is similar. Therefore, in the second embodiment, parts different from the first embodiment will be described in detail, and the description of the other overlapping parts will be omitted as appropriate.

  As shown in FIG. 5, the image display apparatus 150 of the second embodiment reflects the light source 10, the scanning mirror 20 that reflects the light from the light source 10, and the scanning mirror 20 as in the first embodiment. And a reflective diffractive optical element 130 for diffracting light and displaying it to the observer.

  The reflective diffractive optical element 130 is made of a flat material, and includes a substrate 31, a deflecting element 32, and a light reducing element 133 from the light source 10 side. The light reducing element 133 of the second embodiment is a polarizing plate.

  The direction of the polarizing plate is set to be orthogonal to the polarization of the light source 10. Therefore, by disposing the polarizing plate, light transmitted through the substrate 31 and the deflecting element 32 is blocked. That is, leakage of image light from the reflective diffractive optical element 130 to the outside can be suppressed. On the other hand, since the ambient light is naturally polarized, even when the polarizing plate is disposed, all the light is not blocked, and the ambient light can be observed.

  Among the polarizing plates, it is preferable to use a wire grid polarizing plate. In this case, the wavelength of the light source 10 to be used is more preferably specified. By using the light source 10 having such a wavelength, it is possible to substantially eliminate the light transmitted through the wire grid polarizer.

  However, if the wavelength is shifted by several nm from the defined wavelength, the extinction ratio may be greatly reduced (for example, about 1/10). That is, the amount of image light passing through the reflective diffractive optical element 130 increases.

  As described above, by using the wire grid polarizing plate, the reflection type diffractive optical element 130 can be compared with a general polarizing plate (for example, an extinction ratio of about 1/100) if the setting wavelength is well matched. It is possible to almost eliminate the transmitted image light.

  In addition, by using a polarizing plate as the light reducing element 133, the cost can be suppressed as compared with the dichroic mirror of the first embodiment. That is, compared to the dichroic mirror, the polarizing plate can be procured inexpensively.

  As described above, according to the image display device 150 of the second embodiment, the following effects can be obtained.

  (4) According to the image display device 150 of the second embodiment, since a polarizing plate is used as the light reducing element 133, it is possible to reflect or absorb the zero-order light transmitted through the deflecting element 32 in the light from the light source 10. This can prevent the zero-order light from leaking to the outside of the head mounted display 1000. Thus, for example, it can be suppressed that another person can see the image light. Moreover, the light which permeate | transmits a wire grid polarizing plate can be substantially lose | eliminated by using a wire grid polarizing plate. In addition, the polarizing plate can be procured cheaper than the dichroic mirror.

Third Embodiment
<Configuration of Image Display Device>
FIG. 6 is a schematic view showing the configuration of the image display device of the third embodiment. Hereinafter, the configuration of the image display device will be described with reference to FIG.

  The image display apparatus 250 of the third embodiment is different from the first embodiment in the portion in which the shape of the reflective diffractive optical element 230 is a curved shape, and the other portions are substantially the same. . Therefore, in the third embodiment, portions different from the first embodiment will be described in detail, and the description of other overlapping portions will be appropriately omitted.

  As shown in FIG. 6, the image display device 250 of the third embodiment reflects the light source 10, the scanning mirror 20 that reflects the light from the light source 10, and the scanning mirror 20 as in the first embodiment. And a reflective diffractive optical element 230 that diffracts the image light and displays it on the viewer.

  As a feature of the third embodiment, the deflecting element 232 and the light reducing element 233 constituting the reflective diffractive optical element 230 are curved. Specifically, a volume hologram as the deflecting element 232 from the light source 10 side, and a dichroic mirror as the light reducing element 233 so as to cover the volume hologram, for example, are arranged. The reflective diffractive optical element 230 configured of these components has a curved shape in which the end 230 a of the reflective diffractive optical element 230 is bent toward the light source 10 side.

  As described above, by forming the reflective diffractive optical element 230, it is possible to correct the shape distortion and astigmatism of the image plane due to the image light by the bending of the deflection element 232 and the light reduction element 233.

  In addition, by using a volume hologram as the deflection element 232, it is possible to combine multilayering and a curved surface shape, and it is possible to improve the diffraction efficiency. Therefore, a bright image with little noise can be obtained.

  As described above, according to the image display device 250 of the third embodiment, the following effects can be obtained.

  (5) According to the image display device 250 of the third embodiment, since the deflection element 232 and the light reduction element 233 are curved, the image light is compared with the case where the deflection element 32 and the light reduction element 33 are flat. Correction of shape distortion and astigmatism of the image plane due to the curvature of the deflection element 232 and the light reduction element 233 can be performed, and image light with high resolution can be obtained.

  The aspect of the present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the scope or spirit of the invention which can be read from the claims and the entire specification, and the technique of the aspect of the present invention It is included in the scope. Moreover, it can also implement in the following forms.

(Modification 1)
As described above, the present invention is not limited to the use of a diffractive optical element (volume hologram) as the deflecting element 32. For example, a half mirror may be used. Also, as in the second embodiment, even when a polarizing plate is used as the light reducing element 33, a half mirror may be used as the deflecting element 32.

  DESCRIPTION OF SYMBOLS 10 ... Light source, 20 ... Scanning mirror, 30 ... Reflection type diffractive optical element, 31 ... Substrate, 32 ... Deflection element, 33 ... Dimming element, 50 ... Image display apparatus, 100 ... Main body part, 110A ... Display part for right eyes, DESCRIPTION OF SYMBOLS 110B ... Display part for left eyes, 120A, 120B ... Image formation part, 130 ... Reflection type diffractive optical element, 131A, 131B ... Visual recognition part, 133 ... Dimming element, 140 ... Frame, 150 ... Image display apparatus, 200 ... Control part 210: operation unit 230: reflection type diffractive optical element 230a: end portion 232: deflection element 233: light attenuating element 220: operation button section 300: cable 1000: head mounted display

Claims (9)

A light source that outputs light obtained by multiplexing the light output from the first laser light source and the second laser light source;
A scanning mirror that reflects the combined light, and a diffractive optical element that is disposed at a position where the light from the scanning mirror is incident and that deflects at least a portion of the incident combined light in a direction different from specular reflection ,
A light reduction element which is disposed on the opposite side to the light source of the diffractive optical element and which suppresses the emission of the light transmitted through the diffractive optical element without being deflected by the diffractive optical element among the multiplexed light.
Equipped with
The light reducing element has a first wavelength range and a second wavelength range as a wavelength range to be reflected,
The peak wavelength of the light output from the first laser light source is included in the first wavelength range,
The peak wavelength of the light output from the second laser light source, an image display device comprising Rukoto included in the second wavelength range. In the image display device according to claim 1,
The image display device, wherein the diffractive optical element is a volume hologram. In the image display device according to claim 1,
The image display device, wherein the diffractive optical element is a surface relief hologram or a blazed diffraction grating. The image display device according to any one of claims 1 to 3 .
The image display apparatus, wherein the diffractive optical element and the light reducing element are curved.   The image display device according to any one of claims 1 to 4.
  The width of the first wavelength range and the second wavelength range is 5 nm to 20 nm.   The image display device according to any one of claims 1 to 5.
  The first laser light source outputs a red laser,
  The image display apparatus, wherein the second laser light source outputs a blue laser.   A light source that outputs combined light of lights output from the first laser light source, the second laser light source, and the third laser light source;
  A scanning mirror that reflects the combined light
  A diffractive optical element disposed at a position where light from the scanning mirror is incident and deflecting at least a part of the incident combined light in a direction different from that of specular reflection;
  A light reduction element which is disposed on the opposite side to the light source of the diffractive optical element and which suppresses the emission of the light transmitted through the diffractive optical element without being deflected by the diffractive optical element among the multiplexed light.
Equipped with
  The light reducing element has a first wavelength range, a second wavelength range, and a third wavelength range as a wavelength range to be reflected,
  The peak wavelength of the light output from the first laser light source is included in the first wavelength range,
  The peak wavelength of the light output from the second laser light source is included in the second wavelength range,
  An image display device characterized in that a peak wavelength of light output from the third laser light source is included in the third wavelength range.   In the image display device according to claim 7,
  The first laser light source outputs a red laser,
  The second laser light source outputs a blue laser,
  The image display apparatus, wherein the third laser light source outputs a green laser. A wearable image display device comprising the image display device according to any one of claims 1 to 8 .

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