JP2012002889A - See-through type image display device - Google Patents

Abstract

When an observer observes the outside world superimposed on a display image, only the outside world can be imaged with the same angle of view as that when the observer observes the outside world. A see-through image display device is provided.
An image display device includes: (a) an image display unit 10 that emits display light according to an image signal; (b) display light that is emitted from the image display unit 10 and incident along a display light incident optical path OP1; And a light combining unit 50 that combines external light incident along the optical path OP3 of the external light on the common optical paths OP2 and OP4 and emits the combined light to the eyes of the observer; and (c) the optical path OP3. An external field imaging unit 60 for imaging the external world by the incident external light that is incident on the optical path O5 on the extension of the optical path OP1 from the optical multiplexing unit. (d) It includes a display light limiting unit 70 that optically limits the incidence of display light on the external imaging unit.
[Selection] Figure 1

Description

  The present invention relates to a see-through type image display apparatus that displays an image as a display image in accordance with an image signal and allows the observer to observe the display image by superimposing the display image on the outside world. The present invention relates to a technique for imaging only the outside world when the outside world is observed on the display image.

  As an image display device that displays an image to an observer, display light (also referred to as “image light”) representing an image to be displayed is incident on the pupil of the eyeball of the observer, thereby causing the observer to A direct-view image display device that displays an image is already known (for example, see Patent Document 1).

  When this direct-view type image display device is classified according to the display light forming method, it is a spatial modulation type, that is, a liquid crystal that forms the display light by using light source and incident light from the light source, according to the image signal. And a light source that emits light having an intensity corresponding to an image signal, and incident light from the light source. And the optical scanning unit that forms the display light by scanning.

  Further, when direct-view type image display devices are classified according to the display image observation method, see-through type, that is, an observer can observe the actual outside world superimposed on the display image by the image display device. (See, for example, Patent Document 1) and the sealed type, that is, the type that blocks incident light from the actual outside world and allows the observer to observe only the display image.

As a see-through type image display device, a format including an external imaging unit that images the external environment observed by an observer is already known (see, for example, Patent Document 1). In this type of see-through type image display apparatus, an observer generally observes (a) an image display unit that emits display light for displaying an image, and (b) display light that is emitted from the image display unit. A combining unit that combines outside light, which is light from the outside, on a common optical path, and light emitted from the combining unit is incident on the observer's eyes; An external world imaging unit that images the external world being observed at the same angle of view as when the observer observes the external world is configured.
JP 2000-75240 A

  The present inventor, as a form of an external imaging unit mounted on a see-through type image display device, can capture the external world observed by the observer at the same angle of view as when the observer observes the external world. A possible external imaging unit was proposed. Specifically, the outside imaging unit is incident on the multiplexing unit along the optical path extending toward the outside of the common optical path in the multiplexing unit, and the outside light emitted from the multiplexing unit is incident on the outside imaging unit. However, it is designed so that the outside world observed by the observer is imaged by the incident outside light.

  However, when this external imaging unit is employed, if an external world is imaged by the external imaging unit, not only external light but also display light may enter the external imaging unit. In the external imaging unit, the incident display light is noise, that is, unnecessary light for the external light to be imaged. For this reason, it is effective to prevent the display light from entering the external imaging unit in order to improve the quality of the image captured by the external imaging unit.

  Against the background described above, the present invention is the same as the angle of view when the observer is observing the outside world only when the observer observes the outside world over the display image. An object of the present invention is to provide a see-through type image display device capable of imaging at an angle of view.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as technical features of the present invention although they are not described in the following embodiments.

  Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on the nature.

(1) A see-through type image display device that displays an image as a display image in accordance with an image signal and allows an observer to observe the display image by superimposing the display image on the outside world,
In response to the image signal, an image display unit that emits display light for displaying the display image;
The display light emitted from the image display unit and incident along the display light incident optical path and the external light incident along the external light incident optical path from the external environment observed by the observer are extended from the external light incident optical path. A combining unit that combines the display light and the external light on a common optical path and emits the combined light to an observer's eye, which is the upper optical path;
Out of the external light that is incident on the combining unit along the outside light incident optical path and is emitted from the combining unit, the light is finally output from the combining unit to the display light incident optical path or an optical path on its extension. The incident part is incident as partial external light, and the incident partial external light is used as imaging external light that represents the external field observed by the observer, thereby imaging the external field observed by the observer. And
The imaging external light and the display light are disposed at the positions where the imaging external light and the display light are incident. The imaging external light is allowed to enter the external imaging unit, but the display light is optically incident on the external imaging unit. A display-through image display device including a display light restriction unit that restricts the display.

(2) The display light is first polarized light linearly polarized in the first polarization direction,
The display light limiting unit includes a first optical element and a second optical element,
Both the first optical element and the second optical element transmit a part of incident light and reflect the rest,
At least one of the first optical element and the second optical element transmits the first polarized light, and reflects the second polarized light linearly polarized in the second polarization direction orthogonal to the first polarization direction. Having polarization characteristics
The combining unit reflects a part of the display light incident along the display light incident optical path and emits the reflected light to the common optical path, and transmits the remaining part of the display light incident optical path. On the other hand, the external light incident along the external light incident optical path passes through a part of the external light and is output to the common optical path, and the remaining light is reflected. It is emitted to the optical path on the extension of the display light incident optical path,
In the first optical element, external light transmitted through the combining unit and display light reflected from the combining unit are incident along the common optical path, and each of the incident external light and display light is incident on the first optical element. Among them, the light that passes through the first optical element is emitted to the observer's eyes, and the incident external light that is reflected from the first optical element is emitted to the combining unit,
The multiplexing unit reflects a part of the external light incident from the first optical element and emits it to the second optical element,
The second optical element emits display light incident from the image display unit that passes through the second optical element to the combining unit and at least a part of external light incident from the combining unit. The see-through type image display device according to item (1), wherein the see-through type image display device reflects the light and emits the light to the outside imaging unit.

(3) Either the first optical element or the second optical element is a polarization beam splitter having the polarization characteristic, or one of the first optical element and the second optical element has the polarization characteristic. The see-through image display device according to item (2), wherein the other is a polarization beam splitter and the other is a half mirror.

(4) The image display unit
A light source;
A liquid crystal that forms the display light as linearly polarized light using incident light from the light source and that operates according to the image signal,
The see-through type according to (2) or (3), wherein the first optical element and the second optical element having the polarization characteristics have polarization characteristics that transmit linearly polarized light formed by the liquid crystal. Image display device.

(5) The image display unit
A laser light source that emits a light beam having an intensity corresponding to the image signal as a linearly polarized light beam;
An optical scanning unit that forms the display light by scanning an incident light beam from the laser light source, and
The see-through type according to (2) or (3), wherein the first optical element and the second optical element having the polarization characteristics have polarization characteristics that transmit a linearly polarized light beam emitted from the laser light source. Image display device.

(6) For the display light incident along the display light incident optical path, the multiplexing unit reflects a part of the display light and emits it to the common optical path, and transmits the rest of the display light to transmit the display light. On the other hand, the external light incident along the external light incident optical path is transmitted through a part of the light and is output to the common optical path, and the rest is output to the common optical path. It is reflected and emitted to the optical path on the extension of the display light incident optical path,
The image display unit is geometrically related to an exit pupil position for the display light, which is located on an optical path on an extension of the display light incident optical path,
The external imaging unit is geometrically related to an entrance pupil position for the external light, which is located on an optical path on an extension of the display light incident optical path, and the entrance pupil position coincides with the exit pupil position. ,
The external light cross section which is a cross section when the external light is incident on the entrance pupil position is larger than the display light cross section which is a cross section when the display light is incident on the entrance pupil position,
The see-through image display device according to (1), wherein the display light restriction unit includes a mask that is installed at the entrance pupil position and includes a light shielding region that substantially covers the display light section.

  According to the present invention, thanks to the presence of the display light limiting unit, only the external light is incident on the external field imaging unit at the same angle of view as when the observer observes the external world over the display image. To do. Therefore, the external field imaging unit can capture the external field at the same angle of view as that when the observer observes the external field without being affected by the display light that is unnecessary light. Therefore, according to the present invention, the display image does not appear as a noise image in the image captured by the external imaging unit, and as a result, the external environment can be captured faithfully.

1 is an optical path diagram conceptually showing a see-through type head mounted display device (hereinafter abbreviated as “HMD”) according to a first embodiment of the present invention. 3 is a flowchart for explaining data processing in an example of display image control using an image captured by an external imaging unit shown in FIG. 1. FIG. 7 is a front view illustrating an example of an image observed by an observer using the HMD illustrated in FIG. 1 in order to describe another example of display image control using an image captured by the external imaging unit illustrated in FIG. 1. . It is a flowchart for demonstrating the data processing in the said control demonstrated with reference to FIG. 10 is a flowchart for explaining data processing in still another example of display image control using an image captured by the external imaging unit shown in FIG. 1. FIG. 5 is an optical path diagram conceptually showing a see-through type HMD according to a second embodiment of the present invention. It is an optical path figure showing notionally a see-through type HMD according to a 3rd embodiment of the present invention. FIG. 6 is an optical path diagram conceptually showing a see-through type HMD according to a fourth embodiment of the present invention. FIG. 9 is an optical path diagram showing the configuration of the light source unit shown in FIG. 8 more specifically together with an optical device located downstream from the light source unit.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 conceptually shows an optical path diagram of a see-through type head mounted display device (hereinafter abbreviated as “HMD”) according to the first embodiment of the present invention. The HMD is used by being mounted on an observer's head (not shown).

  As shown in FIG. 1, the HMD includes an image display unit 10. The image display unit 10 emits display light for displaying an image (for example, an image represented by data) to be displayed to the observer according to the image signal. For this purpose, the image display unit 10 spatially modulates the planar light emitted from the light source unit 12 for each pixel using the display light forming unit 14. The display light thus formed is projected directly onto the retina 20 of the observer via the eyepiece optical system 15 and the pupil 18 of the observer's eye (one eye) 16. Thereby, the observer can observe the display image as a virtual image.

  As shown in FIG. 1, the light source unit 12 includes a white LED 30 as a light source and a field lens 32 into which white light enters from the white LED 30. In FIG. 1, a position indicated by a circle on the white LED 30 indicates a pupil position (pupil conjugate position) for the image display unit 10. The white LED 30 is driven by the LED driver 34 based on a drive signal supplied from the outside, and thereby emits white light.

  The display light forming unit 14 is configured to include an LCD (liquid crystal display) 40 as a flat panel display (an example of a spatial modulation element). The LCD 40 includes a color filter (RGB filter) that separates the white light from the field lens 32 into three color component lights (RGB) for each pixel, and a liquid crystal panel that controls the transmittance of each component light. It is configured as follows. The liquid crystal panel has a plurality of pixels, and controls the transmittance of each component light for each pixel.

  The LCD 40 is driven by an LCD driver 42, whereby spatial modulation is performed on white light emitted from the white LED 30. The LCD driver 42 controls the LCD 40 for each pixel based on an image signal (video signal) supplied from the outside.

  In addition, in this embodiment, the LCD 40 uses the white LED 30 as a point light source as a light source. Instead, for example, the LCD 40 can be changed to a backlit LCD. In that case, the backlight is used as the light source of the LCD 40.

  The HMD is configured to include a half mirror 50 as a light guide for guiding display light from the eyepiece optical system 15 to the pupil 18. Since the light guide is configured as the half mirror 50, the observer observes the actual outside world through the half mirror 50 and simultaneously receives the display light from the eyepiece optical system 15 by the reflection of the half mirror 50 and displays the display image. Can be observed. In other words, the HMD is a see-through type that can observe a display image superimposed on the actual outside world. The half mirror 50 functions as a multiplexing unit that combines display light and external light, which is light from the outside, on a common optical path.

  As shown in FIG. 1, in this HMD, a first optical path OP <b> 1 (an example of “display light incident optical path” in the item (1)) in which display light travels to the half mirror 50 in the image display unit 10, and display light Is formed from the second optical path OP2 (an example of the “common optical path” in the item (1)) in which the display light travels until it reaches the retina 20 after being reflected from the half mirror 50. A position indicated by a circle on the second optical path OP2 indicates the position of the exit pupil for the image display unit 10 (which coincides with the position of the pupil 18). Further, each X mark on the first optical path OP1 and the second optical path OP2 indicates the imaging position of the display light.

  In this HMD, further, the third light path OP3 (an example of the “outside light incident light path” in the item (1)) in which the outside light travels to the half mirror 50 and the outside light pass through the half mirror 50 and the retina 20. The fourth optical path OP4 (an example of the “common optical path” in the item (1)) in which the external light travels before reaching the position is also formed. The fourth optical path OP4 coincides with the second optical path OP2. Thanks to this coincidence, the display light and the external light are combined on a common path and enter the observer's eye 16. Therefore, according to the HMD, the observer can simultaneously observe the display image and the outside world by overlapping them with the same angle of view.

  As shown in FIG. 1, the HMD further captures the outside world that the observer observes over the display image at the same angle of view as when the observer observes the outside world. 60.

  After the outside light is incident on the half mirror 50, a part of the outside light is transmitted through the half mirror 50 and is incident on the pupil 18, while the remaining part is incident on the half mirror 50 by the half mirror 50. Reflected toward the opposite side of the image display unit 10 with respect to the position. The reflected external light (an example of each of “partial external light” and “imaging external light” in the item (1)) is a fifth optical path OP4 (the above (1)) located on an extension line of the first optical path OP1. , And enters the external imaging unit 60 before long.

  The external light passes through the third optical path OP3 and the fifth optical path OP5 in order and enters the external imaging unit 60. The third optical path OP3 is an optical path obtained by extending an optical path that coincides with the fourth optical path OP4, that is, the second optical path OP2, toward the outside. Accordingly, the external light enters the external imaging unit 60 through the extended optical path and the fifth optical path OP5 in order.

  In FIG. 1, a circle on the fifth optical path OP5 indicates the position of the entrance pupil for the external imaging unit 60 and the position of the exit pupil for the image display unit 10. The position of the entrance pupil and the position of the exit pupil coincide with each other geometrically, and both are pupil conjugate positions that are optically conjugate with the position of the pupil 18.

  As shown in FIG. 1, the external imaging unit 60 includes a CCD (Charge Coupled Device) 62 as an imaging element. External light (that is, the imaging external light) enters the CCD 62, whereby the external imaging unit 60 can image the external environment observed by the observer. In FIG. 1, the X mark on the CCD 62 indicates the imaging position of external light.

  When the display light emitted from the image display unit 10 enters the half mirror 50, a part of the incident display light is reflected by the half mirror 50 and travels toward the pupil 18 as described above. The portion travels along the fourth optical path OP <b> 1 and attempts to enter the external imaging unit 60.

  That is, in the present embodiment, the display light travels toward the entrance pupil position along the same optical path as the optical path where the external light enters the external imaging unit 60. In the present embodiment, the display light is a cross section of the display light when the external light cross section (beam waist of the external light) that is a cross section when the external light enters the entrance pupil position. The optical system (not shown) of the external imaging unit 60 is designed to be larger than the cross section (the beam waist of the display light).

  Only the external light is necessary to image the external environment observed by the observer overlaid on the display image. However, in the present embodiment, the external imaging unit 60 is installed at a position facing the image display unit 10 on the same optical path with the half mirror 50 interposed therebetween. In addition to external light as the display light, display light as unnecessary light also enters the external image pickup unit 60. Therefore, if no countermeasure is taken, a display image is reflected in a captured image obtained by capturing the outside world. The display image exists in the captured image as a noise image.

  Therefore, in the present embodiment, the relative positional relationship between the image display unit 10 and the external imaging unit 60 is set so that the position of the exit pupil of the image display unit 10 matches the position of the entrance pupil of the external imaging unit 60. In addition, a mask 70 (an example of the “display light limiting unit” in the item (1)) is installed at the position of the entrance pupil of the external imaging unit 60. The mask 70 has a light-shielding region 72 that substantially covers the display light section and a light-transmitting region 72 located outside the light-shielding region 72. In the present embodiment, the mask 70 is installed inside the external imaging unit 60, but the installation position is not limited thereto.

  Therefore, in the present embodiment, since the display light is blocked by the light shielding region 72 of the mask 70, the display light does not need to enter the external imaging unit 60. On the other hand, the external light passes through the transparent region 74 of the mask 70 and enters the external imaging unit 60.

  In the present embodiment, the external light, which is the necessary light, is partially blocked by the light shielding region 72 of the mask 70 at the center thereof. However, the position of the outside world to be imaged is somewhat away from the position of the entrance pupil, and light is emitted in a plurality of directions from one point on the outside world to be imaged. Even if a part of the light is blocked by the light blocking area 72 of the mask 70, the remaining part passes through the light transmitting area 74 of the mask 70 and enters the CCD 62. Therefore, the presence of the light shielding region 72 of the mask 70 prevents the image obtained by capturing the outside world from being substantially affected.

  In the present embodiment, the image display unit 10, the half mirror 50, and the external imaging unit 60 are supported by a common frame (not shown). In this state, the HMD is the head of the observer. Used by being attached to. The half mirror 50 is installed outside the image display unit 10 and the external imaging unit 60, but the installation position is not limited thereto, and may be installed inside the image display unit 10, for example. You may install in the outside imaging part 60. FIG.

  As shown in FIG. 1, the image display unit 10 and the external imaging unit 60 are electrically connected to a controller 90 having a computer 80 as a main component, or can communicate wirelessly. The computer 80 controls the image display unit 10 and the external imaging unit 60 by executing a predetermined program.

  In the present embodiment, the external imaging unit 60 captures the external world observed by the observer over the display image, and acquires the captured image as imaging data. The computer 80 can realize various functions by referring to and using the captured image.

  In one example, as schematically shown in the flowchart in FIG. 2, the computer 80 first represents the brightness of the captured image (for example, a plurality of pixels constituting the captured image) based on the captured data in step S <b> 1. Measure the brightness of at least one pixel (eg, the center pixel).

  Next, in step S2, the brightness of the outside world is estimated from the measured value. Subsequently, in step S3, the brightness of the display image is corrected in relation to the estimated value. For example, when the brightness of the outside world is brighter than the standard value, the luminance of the display image can be increased from the standard value so that the viewer can nevertheless observe the display image clearly.

  In another example, as shown in FIG. 3A, in a first window (for example, a rectangular area) 94 out of a maximum area (maximum size of a display image) 92 of an image that can be formed by display light, When the observer observes an actual image of the outside world (for example, a character string “abc”), the computer 80 firstly displays a flowchart shown in FIG. As shown in FIG. 5, a frame image representing a frame (for example, a dashed frame) for visualizing the outer shape of the first window 94 is displayed by display light.

  Next, in step S22, the same partial image (partial imaging data) as the actual image of the outside world (for example, a character string “abc”) existing in the first window 94 among the captured images (imaging data) is the target image. Choose as. Subsequently, in step S23, the selected target image is enlarged at a predetermined magnification. The enlarged target image is displayed in a second window 96 (for example, a solid line frame) 96 that does not overlap the first window 94 as shown in FIG. Accordingly, the observer can simultaneously observe the real image of the outside world and a display image obtained by enlarging the real image of the outside world using the captured image. At this time, the observer observes an image obtained by synthesizing the real image (image by external light) and the display image (image based on the image signal).

  In yet another example, as schematically shown in the flowchart in FIG. 5, the computer 80 first moves the CCD 62 in the imaging direction, for example, in the external imaging unit 60 to focus the captured image (step S41). For example, the distance between the outside imaging unit 60 and the outside world is measured by performing focusing in the center direction of the field angle range in the up and down direction and the right and left direction and using the result of the focusing.

  Next, in step S42, by using the measured distance, an optical device such as a lens in the image display unit 10 is moved so that the focus of the display image is just in the position of the outside world. As a result, the observer can simultaneously observe the outside world and the display image at the same focus position.

  As is clear from the above description, according to the present embodiment, after the display light from the image display unit 10 passes through the half mirror 50, the external image is taken along the same optical path as the external light (fourth optical path OP4). The display light is prevented from entering the CCD 62 of the external imaging unit 60 by the light-shielding region 72 of the mask 70, although it is going to enter the CCD 62 of the unit 60. Thereby, only the external light is separated by the mask 70 from the combined light of the external light (necessary light) and the display light (unnecessary light) combined on the same optical path.

  As a result, only the external light is incident on the CCD 62 of the external imaging unit 60, and thus the external imaging unit 60 can image the external world without being affected by display light that is unnecessary light. Therefore, according to the present embodiment, the display image does not appear as a noise image in the captured image, and thus the outside world can be imaged faithfully.

  Next, a second embodiment of the present invention will be described. However, this embodiment differs from the first embodiment only in the configuration of the image display unit, and the other elements are common, so only the image display unit will be described.

  FIG. 6 conceptually shows a see-through HMD according to the present embodiment in an optical path diagram. The HMD includes an image display unit 100 having a configuration different from that of the first embodiment, and a half mirror 50, an external imaging unit 60, and a mask 70 having the same configuration as that of the first embodiment.

  In general, the image display unit 100 uses a scanner of the display light forming unit 154 to display a planar display of beam-shaped light incident from the light source unit 152 and modulated for each pixel. The light is converted into light, and the display light thus formed is projected directly onto the retina 20 of the observer via the observer's pupil 18. That is, this HMD is a scanning type unlike the first embodiment.

  The light source unit 152 includes a laser 160 that emits a red laser beam, a laser 162 that emits a green laser beam, and a laser 164 that emits a blue laser beam. The laser beams 160, 162, and 164 are modulated by the individual laser drivers 170, 172, and 174 based on image signals supplied from the outside. The three color laser beams emitted from the lasers 160, 162, and 164 are combined as one laser beam that reflects the color of the corresponding pixel. The synthesized laser beam is incident on the display light forming unit 154.

  The display light forming unit 154 includes a main scanning mirror 180 (for example, a resonance mirror) that is driven to scan the laser beam incident from the light source unit 152 in the main scanning direction, and the laser beam incident from the main scanning mirror 180. This time, a sub-scanning mirror 182 (for example, a galvanometer mirror) that is driven to scan in the sub-scanning direction perpendicular to the main scanning direction is provided. In FIG. 6, the position indicated by a circle on the main scanning mirror 180 indicates the position of the pupil (pupil conjugate position) for the image display unit 300. The main scanning mirror 180 is driven by a main scanning mirror driver 190 based on a driving signal supplied from the outside, and the sub scanning mirror 182 is driven by a sub scanning mirror driver 192 based on a driving signal supplied from the outside. Is done.

  The display light forming unit 154 further includes a front relay lens 200, a rear relay lens 202, and an eyepiece optical system 204. The pre-stage relay lens 200 is disposed at the same position as the intermediate image plane between the main scanning mirror 180 and the sub-scanning mirror 182. The laser beam emitted from the rear relay lens 202 passes through the eyepiece optical system 204 and enters the half mirror 50.

  Similar to the first embodiment, according to the present embodiment, the display light from the image display unit 100 passes through the half mirror 50 and then enters the CCD 62 of the external imaging unit 60 through the light shielding region 72 of the mask 70. As a result, only external light is incident on the CCD 62 of the external imaging unit 60. Therefore, it is possible to capture the outside world faithfully without causing the display image to appear as a noise image in the image captured by the outside imaging unit 60.

  Next, a third embodiment of the present invention will be described. However, since the present embodiment has elements common to the first embodiment, the common elements are referred to by using the same reference numerals, and redundant description is omitted, and only different elements are detailed. Explained.

  FIG. 7 schematically shows a see-through type HMD according to the present embodiment in an optical path diagram. The HMD includes an image display unit 300 and an external imaging unit 302. Similar to the first embodiment, the image display unit 300 includes the light source unit 12 and the display light forming unit 310 mainly composed of the LCD 40, whereby the HMD is classified as a spatial modulation type. . As is well known, the LCD 40 emits a plurality of pixel lights from a plurality of pixels as a plurality of linearly polarized lights having the same polarization direction.

  The image display unit 300 further includes an eyepiece optical system 312. Unlike the first embodiment, the eyepiece optical system 312 includes not only the eyepiece lens 314 but also the half mirror 50 and display light as a combining unit. It also has first and second polarization beam splitters 320 and 322 that function as limiting units. Although both display light and external light are incident on the eyepiece optical system 312, the display light is incident as linearly polarized light (having a first polarization direction parallel to the direction indicated by the arrow in FIG. 7). External light is normally incident as non-polarized light (random light). The external imaging unit 302 has a CCD 62 as in the first embodiment.

  First, the eyepiece optical system 312 will be schematically described. The display light (linearly polarized light having the first polarization direction) L1 emitted from the LCD 40 is transmitted through the second polarization beam splitter 322 and enters the half mirror 50. Then, the light is reflected, passes through the first polarizing beam splitter 320, and enters the pupil 18. On the other hand, the external light L2 passes through the half mirror 50. Subsequently, only the component having the first polarization direction among the transmitted external light passes through the first polarizing beam splitter 320 and enters the pupil 18. Incident.

  To describe the eyepiece optical system 312 more specifically, the first polarization beam splitter 320 transmits only the display light (linearly polarized light having the first polarization direction) L1 incident from the half mirror 50. Do substantially. The first polarization beam splitter 320 substantially transmits only the component L2A having the first polarization direction out of the external light L2 incident from the half mirror 50, but with respect to the other components L2B. In effect, only the reflection is performed.

  Of the external light incident on the first polarization beam splitter 320, the component L2B other than the L2A (linearly polarized light having a second polarization direction substantially orthogonal to the first polarization direction) is reflected by the first polarization beam splitter 320. Then, after being reflected by the half mirror 50 again, it enters the second polarization beam splitter 322, but is reflected again and enters the external imaging unit 302. Since the display light L1 that has entered the first polarizing beam splitter 320 is not reflected from the first polarizing beam splitter 320, it does not enter the second polarizing beam splitter 322 and does not enter the external imaging unit 302.

  The second polarization beam splitter 322 substantially transmits only the display light (linearly polarized light having the first polarization direction) L1 incident from the LCD 40. The transmitted display light (linearly polarized light having the first polarization direction) L 1 is reflected by the half mirror 50 and then enters the first polarization beam splitter 320. Since the display light L1 incident on the second polarizing beam splitter 322 from the LCD 40 is not substantially reflected by the second polarizing beam splitter 322, no light loss occurs.

  The second polarization beam splitter 322 substantially only reflects the external light (polarized light not having the first polarization direction) L2B incident from the first polarization beam splitter, and the reflected external light L2B. Enters the external imaging unit 302. The external light L2B incident from the first polarizing beam splitter transmits the second polarizing beam splitter 322 and does not enter the LCD 40, so that no light loss or stray light occurs.

  Therefore, according to the present embodiment, the display light L1 from the image display unit 300 is prevented from entering the external imaging unit 302 due to the presence of the first and second polarization beam splitters 320 and 322, and as a result, Only the external light L2B (an example of each of “partial external light” and “external light for imaging” in the item (1)) is incident on the external imaging unit 302. Therefore, it is possible to capture the outside world faithfully without causing the display image to appear as a noise image in the image captured by the outside imaging unit 302.

  Furthermore, in the present embodiment, unlike the first and second embodiments, the image display unit 300 and the external imaging unit 302 are arranged on the same side with respect to the position of the half mirror 50, as shown in FIG. ing. Therefore, according to the present embodiment, it is easy to pack the image display unit 300 and the external imaging unit 302 in a compact manner, and as a result, it is easy to reduce the size and weight of the HMD.

  In addition, in another aspect, only the first polarization beam splitter 320 is replaced with a half mirror. In this aspect, unlike the present embodiment, the display light L 1 is emitted from the half mirror and is incident on the second polarization beam splitter 322. The incident display light L1 passes through the second polarizing beam splitter 322 and enters the LCD 40, but does not reflect toward the external imaging unit 302. In this case, the display light L1 also enters the external imaging unit 302. You do n’t have to.

  In addition, in another aspect, only the second polarization beam splitter 322 is replaced with a half mirror. In this aspect, unlike the present embodiment, the display light L1 from the image display unit 300 is reflected by the half mirror, but the reflected display light L1 does not enter the external imaging unit 302. In addition, the display light L1 does not need to enter the external imaging unit 302.

  As is clear from the above description, in the present embodiment, the optical path of the display light L1 from the LCD 40 to the half mirror 50 constitutes an example of the “display light incident optical path” in the item (1), and The optical path of the external light L2 (= L2A + L2B) from the half mirror 50 to the half mirror 50 constitutes an example of the “external light incident optical path” in the same term, and the display light L1 and the external environment between the half mirror 50 and the retina 20 An optical path common to the light L2 (= L2A + L2B) constitutes an example of the “common optical path” in the same term. In the present embodiment, there is no optical path corresponding to the “optical path on the extension of the display light incident optical path” in the same section.

  Next, a fourth embodiment of the present invention will be described. However, since the present embodiment differs from the third embodiment only in the configuration of the image display unit, and other elements are common, only the image display unit will be described.

  FIG. 8 conceptually shows a see-through type HMD according to the present embodiment in an optical path diagram. The HMD includes an image display unit 400 having a configuration different from that of the third embodiment, and a half mirror 50, an external imaging unit 302, and an eyepiece optical system 312 having the same configuration as those of the third embodiment.

  Similar to the second embodiment, the image display unit 400 includes a light source unit 152 and a display light forming unit 410 mainly composed of a scanner, whereby the HMD is classified into a scanning type.

  FIG. 9 specifically shows the configuration of the light source unit 152 in an optical path diagram. In the light source unit 152, each of the lasers 160, 162, and 164 is designed to generate a corresponding laser beam as linearly polarized light having a single polarization direction. Therefore, the display light forming unit 410 forms display light as linearly polarized light, and the formed display light enters the eyepiece optical system 312. Thereby, this embodiment is common to the third embodiment in that the display light is linearly polarized light.

  In the light source unit 152, the red laser beam emitted from the laser 160 is collimated by the lens 400, and then enters and transmits the first dichroic mirror 402. A green laser beam emitted from the laser 162 is collimated by the lens 404 and then incident and reflected on the first dichroic mirror 402. As a result, the first dichroic mirror 402 combines the red laser beam and the green laser beam. The combined light enters the second dichroic mirror 406 and passes therethrough.

  A blue laser beam emitted from the laser 164 is collimated by the lens 408 and then incident and reflected on the second dichroic mirror 406. As a result, the second dichroic mirror 406 combines the red laser beam, the green laser beam, and the blue laser beam. The combined light enters the display light forming unit 410.

  A flexible optical fiber may be used to combine multiple laser beams or transmit the laser beam. In this case, the polarization direction of the laser beam changes as the fiber travels. There is a possibility that. On the other hand, in this embodiment, an optical element that changes the polarization direction of the laser beam, that is, the display light is not used, so that it is not necessary to add a mechanism for adjusting the polarization characteristic of the display light afterwards.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are exemplifications, and are based on the knowledge of those skilled in the art including the aspects described in the section of [Disclosure of the Invention]. The present invention can be implemented in other forms with various modifications and improvements.

Claims (6)

A see-through type image display device that displays an image as a display image in accordance with an image signal and allows an observer to observe the display image superimposed on the outside world,
In response to the image signal, an image display unit that emits display light for displaying the display image;
The display light emitted from the image display unit and incident along the display light incident optical path and the external light incident along the external light incident optical path from the external environment observed by the observer are extended from the external light incident optical path. A combining unit that combines the display light and the external light on a common optical path and emits the combined light to an observer's eye, which is the upper optical path;
Out of the external light that is incident on the combining unit along the outside light incident optical path and is emitted from the combining unit, the light is finally output from the combining unit to the display light incident optical path or an optical path on its extension. The incident part is incident as partial external light, and the incident partial external light is used as imaging external light that represents the external field observed by the observer, thereby imaging the external field observed by the observer. And
The imaging external light and the display light are disposed at the positions where the imaging external light and the display light are incident. The imaging external light is allowed to enter the external imaging unit, but the display light is optically incident on the external imaging unit. A display-through image display device including a display light restriction unit that restricts the display. The display light is first polarized light linearly polarized in the first polarization direction,
The display light limiting unit includes a first optical element and a second optical element,
Both the first optical element and the second optical element transmit a part of incident light and reflect the rest,
At least one of the first optical element and the second optical element transmits the first polarized light, and reflects the second polarized light linearly polarized in the second polarization direction orthogonal to the first polarization direction. Having polarization characteristics
The combining unit reflects a part of the display light incident along the display light incident optical path and emits the reflected light to the common optical path, and transmits the remaining part of the display light incident optical path. On the other hand, the external light incident along the external light incident optical path passes through a part of the external light and is output to the common optical path, and the remaining light is reflected. It is emitted to the optical path on the extension of the display light incident optical path,
In the first optical element, external light transmitted through the combining unit and display light reflected from the combining unit are incident along the common optical path, and each of the incident external light and display light is incident on the first optical element. Among them, the light that passes through the first optical element is emitted to the observer's eyes, and the incident external light that is reflected from the first optical element is emitted to the combining unit,
The multiplexing unit reflects a part of the external light incident from the first optical element and emits it to the second optical element,
The second optical element emits display light incident from the image display unit that passes through the second optical element to the combining unit and at least a part of external light incident from the combining unit. The see-through image display device according to claim 1, wherein the see-through image display device reflects the light and emits the reflected light to the outside imaging unit.   Either the first optical element or the second optical element is a polarization beam splitter having the polarization characteristic, or one of the first optical element and the second optical element is a polarization beam splitter having the polarization characteristic. The see-through type image display device according to claim 2, wherein the other is a half mirror. The image display unit
A light source;
A liquid crystal that forms the display light as linearly polarized light using incident light from the light source and that operates according to the image signal,
4. The see-through image display device according to claim 2, wherein the first optical element and the second optical element having the polarization characteristics have polarization characteristics that transmit linearly polarized light formed by the liquid crystal. 5. . The image display unit
A laser light source that emits a light beam having an intensity corresponding to the image signal as a linearly polarized light beam;
An optical scanning unit that forms the display light by scanning an incident light beam from the laser light source, and
4. The see-through image display device according to claim 2, wherein the first optical element and the second optical element having the polarization characteristics have polarization characteristics that transmit a linearly polarized light beam emitted from the laser light source. 5. . The combining unit reflects a part of the display light incident along the display light incident optical path and emits the reflected light to the common optical path, and transmits the remaining part of the display light incident optical path. On the other hand, the external light incident along the external light incident optical path passes through a part of the external light and is output to the common optical path, and the remaining light is reflected. It is emitted to the optical path on the extension of the display light incident optical path,
The image display unit is geometrically related to an exit pupil position for the display light, which is located on an optical path on an extension of the display light incident optical path,
The external imaging unit is geometrically related to an entrance pupil position for the external light, which is located on an optical path on an extension of the display light incident optical path, and the entrance pupil position coincides with the exit pupil position. ,
The external light cross section which is a cross section when the external light is incident on the entrance pupil position is larger than the display light cross section which is a cross section when the display light is incident on the entrance pupil position,
The see-through type image display device according to claim 1, wherein the display light limiting unit includes a mask that is provided at the entrance pupil position and includes a light shielding region that substantially covers the display light cross section.

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