JP2005070804A - Composite display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical system of a thin type, capable of observing both of the image information displayed on a display means, such as a liquid crystal display, and the image information obtained by an imaging means, and provide a composite display device using the same. <P>SOLUTION: The composite display device has a display optical system which guides the luminous flux from the display means displaying the image information to an observer's eyeball and an imaging optical system for imaging the luminous flux from the external field to an imager. The display device approximately aligns the eyeball optical axis of the incident luminous flux on the observer's eyeball of the display optical system by an optical path separating means disposed in the optical path or the virtual eyeball optical axis extending the eyeball optical axis and the external field optical axis of the luminous flux made incident from the external field of the imaging optical system. The imaging optical system has an incident surface, an exit surface and a plurality of eccentric reflective surfaces which are offcentered from a reference ray Ri and have power. At least one surface among the plurality of the eccentric reflective surfaces is a combination surface commonly used as a transmission surface and a reflective surface. The incident luminous flux from the incident surface is reflected by the plurality of the eccentric reflective surfaces. The luminous flux made incident from the incident surface is reflected by the the plurality of the eccentric reflective surfaces and the reflected luminous fluxes are emitted from the exit surfaces by folding the optical paths. The optical system has a first optical element in which the synthesized power of generator sections is negative. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical element and a composite display device using the same.

In addition, the present invention relates to an optical system suitable for an imaging display device or the like that is thin (thin in the visual axis direction), easy to display and capture a wide angle of view, and has a high degree of layout freedom using an optical element having a free-form surface.

  In addition, the present invention combines an imaging optical system that captures light from image information of the outside world and forms it in the imaging device, and a display optical system that observes image information displayed on a display means such as a liquid crystal, thereby reducing the overall size. The composite display device is particularly suitable for a device called a head-manted display (HMD) or a glasses-type display.

  Conventionally, a small CCD camera is attached to the HMD, and the image information obtained from the small CCD camera is displayed as it is on the HMD, or the image information obtained from the small CCD camera is processed into another image information. Devices have been proposed for converting and displaying it on the HMD.

In addition, various see-through HMDs (HMDs having a configuration in which external light can be directly observed at an angular magnification of approximately 1) have been proposed. In this form of HMD, the optical axis of the eyeball of the display optical system for observing the image information displayed on the display means of the HMD and the optical axis of the CCD camera that forms image information on the outside world on the CCD surface are different. If this is the case, parallax occurs between them, which is not preferable. Devices that have no parallax and have both an imaging optical system and a display optical system have been proposed (Patent Documents 1 to 5).
JP-A-4-22358 Japanese Patent Laid-Open No. 5-303053 JP-A-10-239628 JP 11-174367 A JP 2000-75240 A

  In the display optical system proposed in Patent Document 1, light emitted from a small LCD is imaged on a small camera after passing through a flat half mirror.

  On the other hand, in the imaging optical system, external light is focused on a small camera after passing through a flat half mirror. Since the flat half mirror is disposed at 45 degrees with respect to the optical axis, the apparatus tends to be large.

  In addition, since there is an eyepiece in front of the eyeball, the see-through optical system is not realized.

  Patent Document 2 discloses a configuration in which a see-through optical system is realized, but the optical system is complicated and the apparatus tends to be very large.

  Patent Documents 3 to 5 propose HMDs that solve these problems.

  The composite display devices proposed in these publications include prism-like optical elements (free-form surface prisms) appropriately arranged with so-called free-form surfaces having different powers depending on the azimuth angle in both the display optical system and the imaging optical system. By using the joint surfaces of both free-form surface prisms as optical path separating means such as a half mirror, a small composite display device is realized.

  The present invention further improves the optical system proposed in these, and appropriately configures a free-form surface prism (optical element) and an imaging optical system on the display optical system and the imaging optical system side, thereby reducing the size of the optical axis of the eyeball. An object is to provide an optical element that is thin in the direction and suitable for widening the angle of view, and a composite display device using the optical element.

  In addition, the present invention provides a configuration of a display optical system having a plurality of eccentric reflecting surfaces for guiding a light beam from a display means such as a liquid crystal display (LCD) to an eyeball of an observer, and imaging of external image information such as a CCD. By appropriately setting the configuration of the imaging optical system that forms an image on the element surface, the composite display device can observe and image both pieces of image information in a good state while reducing the size of the entire device. The purpose is to provide.

  It is another object of the present invention to provide a composite display apparatus including a sheath optical system capable of simultaneously observing image information of the outside world in addition to the aforementioned object.

The composite display device according to the first aspect of the present invention includes a display optical system that guides a light beam from a display unit that displays image information to an eyeball of an observer, and an imaging optical system that forms an image of the light beam from the outside on an image sensor. The optical axis of the light beam incident on the eyeball of the observer of the display optical system by the optical path separating means provided in the optical path, or the virtual eyeball optical axis obtained by extending the optical axis of the eyeball, and the outside of the imaging optical system The imaging optical system has a plurality of eccentric reflecting surfaces that are decentered with respect to the incident surface, the exit surface, and the reference ray Ri and have power, on the same medium. And at least one of the plurality of eccentric reflecting surfaces is a dual-purpose surface that serves as both a transmitting surface and a reflecting surface, and the light beam incident from the incident surface is reflected by the plurality of eccentric reflecting surfaces to fold the optical path. It is emitted from the exit surface, and the bus cross-section synthesis Chromatography is characterized in that has a first optical element is negative.

According to a second aspect of the present invention, in the first aspect of the invention, the imaging optical system includes at least one non-rotationally symmetric lens having both a non-rotationally symmetric surface and a rotationally symmetric surface, and a plurality of rotationally symmetric lenses. And having a compound lens group in which the optical axis of the rotationally symmetric surface of the non-rotationally symmetric lens and the optical axis of the rotationally symmetric lens are all substantially coincident,
A light beam from the outside is guided through the first optical element and then guided onto the imaging element by the compound lens group.

According to a third aspect of the present invention, in the second aspect of the present invention, the local bus section cross-section focal length fypout and the local sub-section cross-section focal length fxpout of the exit surface of the first optical element, the bus section cross-section combined focal length fyp of the optical element, and the sub-section The combined focal length fxp is | fyp / fypout | <2 (1)
| Fxp / fxpout | <2 (2)
It is characterized by being comprised so that it may satisfy.

According to a fourth aspect of the present invention, in the third aspect of the invention, the local generating section focal length fyl and the local subsection fxl of the non-rotationally symmetric surface of the compound lens group, the combined section focal length fig and the subsection of the generating section. The combined focal length fxg is
| Fyg / fyl | <1 (3)
| Fxg / fxl | <1 (4)
It is characterized by being comprised so that it may satisfy.

According to a fifth aspect of the present invention, in the invention of the fourth aspect, the bus section combined focal length of the entire system of the imaging optical system is fy, the child section combined focal length is fx, and the bus section combined focal length of the first optical element is fyp, where the cross-sectional cross section combined focal length is fxp,
-1 <fy / fyp <0 (5)
-1 <fx / fxp <0 (6)
It is characterized by being comprised so that it may satisfy.

According to a sixth aspect of the invention, in the fifth aspect of the invention, the distance from the developed entrance pupil position to the exit pupil position of the display optical system when the entrance pupil of the imaging optical system is developed on the visual axis is Dpp, and the display optics When the distance from the exit surface of the system to the exit pupil of the display optical system is er,
0.25 <Dpp / er <8.0 (7)
It is characterized by being comprised so that.

  According to the present invention, it is easy to achieve a thin, lightweight, bright and wide-angle optical system, and the use of the optical system makes it possible to combine a compact, lightweight, wide-angle image display device and imaging device. It becomes easy to achieve the display device.

  FIG. 1 is a schematic diagram of a main part of a first embodiment that constitutes a basic configuration of a composite display device of the present invention. In the figure, reference numeral 101 denotes a display optical system (LCD display optical system), which has a second optical element 7 and guides image information displayed on the LCD 8 as display means to the eyeball E of the observer. Yes. Rd is a light beam from the center of the display surface of the LCD 8 to the center of the exit pupil S formed by the display optical system 101, and Rd is referred to as a display reference light beam. The second optical element 7 has a plurality of eccentric reflecting surfaces that are decentered with respect to the display reference light beam Rd and have power.

  A line obtained by extending a light beam from the exit surface of the second optical element 7 of Rd to the center of the exit pupil S is called an eyeball optical axis. Reference numeral 102 denotes an imaging optical system (CCD imaging optical system), which includes a first optical element 1, an aperture 2, a compound lens group 3, a deflecting means 4, a low-pass filter 5, and the like. The image is formed on the CCD 6. Ri is a light beam that passes through the approximate center of the diaphragm 2 and reaches the center of the light receiving surface of the CCD 6, and Ri is referred to as an imaging reference light beam (reference light beam).

  In addition, a light beam from the outside world of the imaging reference light beam Ri to the incident surface of the first optical element is called an outside optical axis, and a place where the outside optical axis is extended by a predetermined distance to the outside side is called an outside center.

The first optical element 1 of the present embodiment has a plurality of eccentric reflection surfaces that are decentered with respect to the incident surface, the emission surface, and the reference light beam Ri and have power on the same medium, At least one surface is a dual-purpose surface that serves as both a transmissive surface and a reflective surface, and is an optical element that reflects a light beam incident from the incident surface by the plurality of eccentric reflecting surfaces, folds the optical path, and emits the light from the exit surface. ,
The optical element is characterized in that the bus cross-section combined power is negative.

  In this embodiment, a prism body (optical element) using a plurality of internal reflections is used for both the display optical system 101 and the imaging optical system 102. The two prism bodies are joined with the optical path separation means BS as a boundary. The optical path separating means BS is formed of an eccentric reflecting surface that is decentered and has a curvature, and is a surface that separates the optical path of the display optical system 101 and the optical path of the imaging optical system 102. The optical path separation means BS uses one reflection surface in the display optical system 101 and the other reflection surface in the imaging optical system 102. In the present embodiment, the optical path separation means BS is a half mirror.

  The compound lens group 3 has at least one non-rotationally symmetric lens, each of which has a non-rotationally symmetric surface and a rotation-symmetrical surface, and a plurality of rotation-symmetrical lenses. The optical axis and the optical axis of the rotationally symmetric lens are all substantially coincident.

  The optical axis referred to here is the rotational axis of the rotationally symmetric lens and is synonymous with the so-called optical axis used in a normal coaxial optical system.

  Reference numeral 103 denotes a see-through optical system. The see-through optical system 103 uses the incident surface of the imaging optical system 102 as an incident surface for external light, passes through the optical path separation means BS that is a half mirror, and guides it to the eyeball E of the observer using the exit surface of the display optical system 101 as the exit surface. It is burned.

  The decentered reflecting surface in this embodiment maintains good optical performance by making the refractive power different depending on the azimuth angle around the surface apex.

  In the display optical system 101 of the present embodiment, light from the LCD (display unit) 8 is guided to the eyeball E via the second optical element 7. In this way, the display optical system guides the light beam from the LCD 8 to the eyeball E without being reflected and imaged a plurality of times. Thereby, the image information displayed on the LCD 8 is observed.

  In the imaging optical system 102, light from the outside world forms an image on the imaging device CCD 6 through the first optical element 1, the diaphragm 2, the optical system 3, and the filter 5. As a result, image information of the outside world is recorded.

  In the see-through optical system 103 of this embodiment, light from the outside enters the first optical element 1 of the imaging optical system 102, passes through the optical path separation means BS (half mirror), and is the second optical element 7 of the display optical system 101. To the eyeball E. Thereby, the image information of the outside world is observed.

  In the present embodiment, the display optical system 101 and the imaging optical system 102 are arranged to be opposed to each other by the light beam separation means BS, and the reference light beams of the display optical system 101, the imaging optical system 102, and the see-through optical system 103 are substantially the same point on the BS. By passing, the optical axis of the eyeball and the optical axis of the outside world substantially coincide with each other, the image information displayed on the LCD 8 is observed, the image information of the outside world on the CCD 6 and the image information of the outside world are displayed. Observation (see-through optical system) can be simultaneously observed and imaged without parallax.

  Note that the half mirror of the optical path separation means BS is not limited to a ratio of transmittance to reflectance of 1: 1, and the ratio is arbitrary.

  In the present embodiment, the first optical element and the second optical element are made of the same material having a refractive index n of n> 1, and the incident surface of the first optical element 1 and the exit surface of the second optical element 7 are formed. An appropriate shape is set so that the power of the see-through optical system 103 is substantially 0 and the external image is observed almost without distortion by the observer in a state where the external image is approximately 1 in angular magnification.

  Rs is a light beam from the outside center to the center of the exit pupil S of the display optical system 101 via the see-through optical system 103, and Rs is called a see-through reference light beam.

  In the present embodiment, the see-through reference light beam Rs and the imaging reference light beam Ri substantially coincide with each other on the outside (that is, Rs and Ri substantially coincide with the external optical axis), and the see-through reference light beam Rs and the display reference light beam Rd are in the eyeball. Side so that Rs and Rd are substantially coincident with the optical axis of the eyeball, so that display from the LCD, imaging to the CCD, and see-through from the outside world can be performed without parallax, while having a compact configuration. ing.

  FIG. 2 is an explanatory diagram for explaining a reference light beam, a local bus bar cross section, a local bus bar cross section, and the like in the composite display device of the present invention.

  FIG. 3 is a perspective view of a basic configuration example of the composite display device of the present invention.

  First, definitions of terms such as a reference beam, a local bus cross section, a local bus cross section, a bus cross section combined focal length, and a bus cross section combined focal length in the composite display device of the present invention will be described with reference to the drawings.

  In the definition of the conventional system that does not correspond to the eccentric system, if the z-axis is the optical axis in each surface vertex coordinate system, the yz section is the generatrix section according to the conventional definition (the meridional section), and the xz section is the slave line according to the conventional definition Cross section (sagittal cross section). Since the present invention is an eccentric system, a local bus bar cross section and a local child cross section corresponding to the eccentric system are newly defined.

  First, a light beam emitted from the center on the display surface of the display unit 8 and reaching the center of the exit pupil S formed by the display optical system 101 is defined as a display reference light beam Rd.

  Further, a line connecting the hit point S71a of the display reference ray Rd and the center of the exit pupil S on the exit surface S71 of the second optical element 7 at this time is defined as a visual axis. That is, the visual axis coincides with the above-described eyeball optical axis. As shown in FIG. 2, a coordinate system in which the visual axis is the z-axis, the y-axis is perpendicular to the z-axis in the paper plane, and the x-axis is perpendicular to the paper plane is the global coordinate system. I will call it. A ray passing through the line extending so as to be refracted by the surface S71 of the second optical element 7 and the surface S11 of the first optical element 1 with the visual axis in accordance with the law of refraction is defined as a see-through reference ray Rs.

  A light beam that passes through the center of the diaphragm 2 of the image pickup optical system 102 and reaches the center of the image pickup surface of the image pickup device 6 is defined as an image pickup reference light beam (reference light beam) Ri.

On the hit point between each reference ray Rd, Rs, Ri defined as described above and each surface, the surface including the incident light and the emitted light of each reference ray is defined as a local bus cross section, and the local bus cross section including the hit point is defined as A surface that is perpendicular and parallel to a child cross section (normal child cross section) of each surface vertex coordinate system is defined as a local child cross section. When the curvature of the local bus cross section is ry, the curvature of the local child cross section is rx, and the refractive indices before and after the corresponding surface are nd and nd ′, respectively,
fy = ry / (nd′−nd)
Fy given by the local bus section focal length,
fx = rx / (nd′−nd)
Fx given by is defined as the local sub-section focal length.

Also,
φy = 1 / fy, φx = 1 / fx
.Phi.y and .phi.x given by (1) are the local bus cross-sectional power and local sub-line cross-sectional power of each surface, respectively. Now, the i-th local bus cross-sectional power is φyi, the distance between the hit point between the i-th optical surface and each reference ray, and the distance between the hit point between the i + 1-th optical surface and each reference ray, When the value divided by the refractive index is the conversion surface interval ei ′, the combined power obtained in the same manner as the normal paraxial tracking calculation from the m-th surface to the n-th surface is the bus-line cross-sectional combined power φymn, and the reciprocal of φymn Let fymn be a generating section focal length of the generatrix from the m-th surface to the n-th surface.

  Similarly, from the m-th surface to the n-th surface, the local power section cross section power φxi, the combined power obtained for the conversion interval ei ′ between hit points is the subsection cross section combined power φxmn, and the reciprocal thereof is the subsection cross section combined focal length fxmn. .

  Next, the operation of each element in the basic configuration example of the embodiment of FIG. 1 will be described.

  The first optical element 1 and the second optical element 7 are joined together with a surface S12 and a surface S72 having the same shape in a state where a transflective film is formed on at least one surface, and the surface S12 and the surface S72 are optical paths. It functions as the separating means BS.

  The light from the display means 8 enters the second optical element 7 from the incident surface S73. Most of the effective light flux of the incident light is directed to the surface S71 having power arranged eccentric with respect to the display reference light ray Rd, and when the refractive index of the medium of the second optical element 7 is n, the surface S71. Is incident at an incident angle of arcsin (1 / n) or more and totally internally reflected. The light beam reflected in this way is reflected by the surface S72 having a power decentered with respect to the display reference light ray Rd and is directed again to the surface S71. This time, the incident angle is less than arcsin (1 / n) on the surface S71. Incident light is transmitted through the surface S 71 and guided to the exit pupil S formed by the display optical system 101. With the above configuration, the image displayed on the display means 8 is enlarged and presented to an observer who has placed the eyeball E in the vicinity of the exit pupil S. As described above, the optical path is folded by the plurality of decentered reflecting surfaces S71 and S72 that are decentered with respect to the display reference ray Rd, so that the configuration is thin in the visual axis direction.

  Further, the plurality of eccentric reflecting surfaces S71 and S72 are both surfaces having power, so that the number of optical surfaces is reduced. At this time, it is preferable to correct the decentration aberration generated by the decentered reflecting surface having power by setting at least one of the decentering reflecting surfaces to a non-rotationally symmetric surface whose cross section (paper surface) is the only symmetric surface. Furthermore, it is preferable to use a plurality of decentered reflecting surfaces or all surfaces as non-rotationally symmetric surfaces whose cross section is the only symmetry plane, because decentration aberrations can be corrected better.

  Further, the surface S71 which is the decentered reflecting surface is used as a dual-purpose surface which performs the internal total reflection and transmission functions, thereby constituting a display optical system with a reduced number of surfaces and a small amount of light loss.

  Further, the light from the outside that is incident from the incident surface S11 of the first optical element 1 is partially reflected by the eccentric reflecting surface S12 having power decentered with respect to the imaging reference light beam Ri that is a constituent surface of the optical path separating unit BS. Then, it goes toward the decentered reflecting surface S11 having power decentered with respect to the imaging reference light beam Ri. When the refractive index of the medium of the first optical element 1 is n, these lights are incident on the surface S11 at an incident angle of arcsin (1 / n) or more and totally internally reflected, and are emitted from the exit surface S13. And exits the first optical element 1 toward the stop 2. The light that has passed through the diaphragm 2 includes a plurality of rotationally symmetric lenses 31, 32, and 33, and a composite having at least one non-rotationally symmetric lens 34 having one surface that is a rotationally symmetric surface R8 and the other surface that is a non-rotationally symmetric surface FFS1. An image of the outside world is formed on the imaging surface of the imaging device 6 via the lens group 3 and the low-pass filter 5.

  At this time, the negative lead is a so-called retrofocus type by setting the combined power (in the paper plane) of the first optical element 1 which is a portion in front of the stop 2 in the imaging optical system (1-5) to be negative. The imaging optical system can be used, and is configured to be suitable for photographing an external image with a wide angle of view while sufficiently ensuring a so-called back focus in which the filter system 5 enters in an imaging optical element such as a CCD. More preferably, the composite power of the first optical element 1 is also negative, so that the configuration of the optical system suitable for a wide angle of view in the direction of the cross section of the slave line can be obtained.

  In addition, the first optical element 1 has a thin configuration in the visual axis direction by the configuration in which the optical path is folded by a plurality of eccentric reflecting surfaces S11 and S12 that are decentered with respect to the display reference light beam Ri.

  In addition, since the plurality of eccentric reflecting surfaces S11 and S12 are both surfaces having power, the optical surfaces that do not contribute to image formation are eliminated, and the number of optical surfaces is reduced. At this time, it is preferable to correct the decentration aberration generated by the decentered reflecting surface having power by making at least one decentered reflecting surface a non-rotationally symmetric surface having a cross section of the generatrix as the only symmetry surface.

  Furthermore, by making the exit surface S13 close to the stop 2 a non-rotationally symmetric surface with the generatrix section as the only symmetry surface, it becomes easy to correct pupil decentration aberrations.

  More preferably, when a plurality of decentered reflecting surfaces or all surfaces are non-rotationally symmetric surfaces having a cross section as a sole symmetry plane, decentration aberrations can be corrected more satisfactorily.

Further, the surface S11 which is the decentered reflection surface is a dual-purpose surface that performs internal total reflection and transmission, thereby reducing the number of surfaces and reducing optical loss. Here, in the first optical element 1, the surface S12 has a strong negative power, but at least one of the local bus cross-section power and the local child cross-section power of the exit surface S13 is negative, and the negative power is shared. By doing so, it becomes easy to increase the negative power of the first optical element as a whole without increasing the negative power of the surface S12 more than necessary, and a configuration suitable for a wider angle of view can be obtained. Further, the local bus section cross-section focal length fxout and the local sub-section cross-section focal length fxpout on the exit surface S13 of the first optical element 1 and the bus section cross-section combined focal length fyp and the sub-section cross-section combined focal length fxp of the optical element 1 Conditional expression | fyp / fypout | <2 (1)
| Fxp / fxpout | <2 (2)
It is preferable that the bus cross-section combined focal length and the sub-line cross-sectional combined focal length in the first optical element 1 are well balanced by configuring so as to satisfy the above.

  If both the expressions (1) and (2) exceed the upper limit, the decentration aberration generated by the exit surface S13 alone becomes large, which is not preferable.

  In addition, by using at least one non-rotationally symmetric lens in the compound lens group 3 that contributes to image formation behind the diaphragm 2, a high-performance imaging optical system that corrects decentration aberrations that cannot be corrected by the first optical element 1. Making it easier to provide.

  Further, by performing chromatic aberration correction and the like using a plurality of rotationally symmetric lenses, high imaging performance can be obtained while suppressing the number of parts of a non-rotationally symmetric lens that is difficult to manufacture. In the compound lens group 3 of the present embodiment, as shown in FIG. 2, the rotationally symmetric axis of the rotationally symmetric surface constituting the compound lens group 3 is the optical axis in the coaxial optical system (see FIG. 2 is a coaxial configuration that shares a one-dot chain line 3a. With this configuration, the compound lens group 3 includes a non-rotationally symmetric surface, but can be assembled in the same assembly process as that of a normal coaxial optical system, so that it is easy to save the labor required for assembly. . The rotational deviation correction around the optical axis of the non-rotationally symmetric lens can be performed by means such as determining the direction with respect to the lens barrel using a non-rotationally symmetric lens having a shape obtained by cutting a part of a circle. is there.

Further, as shown in the figure, the rotationally symmetric optical axis 3 does not necessarily coincide with the imaging reference light beam Ri. By using such a complex lens group, imaging with less decentration adjustment, in which only the positioning of the three points of the lens barrel having the first optical element 1 and the complex lens group 3 and the imaging element 6 is adjusted including decentering. It becomes easy to provide an optical system. Further, the local bus cross-section focal length fyl and local sub-section cross-section focal length fxl of the non-rotationally symmetric surface in the compound lens group 3, and the bus-bar cross-section composite focal length fyg and the sub-line cross-section composite focal length fxg of the compound lens group 3 are obtained. The following conditional expression | fyg / fyl | <1 (3)
| Fxg / fxl | <1 (4)
By satisfying the above, the bus section cross-section focal length and the child-line cross section focal length are configured to be well balanced. If both the expressions (3) and (4) exceed the upper limit, the decentration aberration generated on the corresponding non-rotationally symmetric surface alone becomes large, which is not preferable. Further, between the bus cross-section combined focal length fy and the child-line cross-section combined focal length fx in the entire imaging optical system, and the bus-bar cross-section combined focal length fyp and the child-line cross-section combined focal length fxp of the first optical element 1 Conditional expression,
-1 <fy / fyp <0 (5)
-1 <fx / fxp <0 (6)
It is desirable to satisfy If the lower limit of the expressions (5) and (6) is exceeded, the power of the first optical element with respect to the power of the entire system becomes too strong, and it is difficult to correct the aberration generated in the first optical element 1 with the compound lens group 3. It becomes.

  If the upper limit is exceeded, it is difficult to achieve a wide angle of view.

  The imaging optical system preferably has a deflecting unit 4. The deflecting means 4 has, for example, a triangular prism column shape as shown in FIG. 3, and deflects the optical path in a direction different from the bus cross section that is the folding direction of the optical path described in FIGS. In FIG. 3, the optical path is configured to be folded substantially perpendicularly to the cross section of the generatrix, and the global coordinate system has a length in the y-axis direction and a length in the z-axis direction that are shortened. It becomes possible to do.

  In addition, light from the outside that is incident from the surface S11 of the first optical element 1 is partially transmitted through the surfaces S12 and S72 that are constituent surfaces of the optical path separating means BS, is incident on the second optical element 7, and is emitted from the surface S71. Thus, the see-through optical system is configured so as to be guided to the observer's eye E, and enables the observer to observe the external world image. At this time, the shapes of the surface S11 and the surface S71 are appropriately designed so that the power of the see-through optical system from the surface S71 to the surface S11 is approximately 0 and the angular magnification is approximately 1. It is possible to reduce the distortion of the external image observed by a person.

At this time, as shown in FIG. 2, the distance from the developed entrance pupil position where the entrance pupil of the imaging optical system is developed on the visual axis to the position of the exit pupil S of the display optical system is Dpp, and the display optical system is constructed. When the distance from the hit point (incident point) of the exiting ray on the exit surface S71 of the two optical element 7 to the position of the exit pupil S is er, the following conditional expression 0.25 <Dpp / er <8.0 (7)
It is preferable that the configuration is satisfied. Here, the unfolded entrance pupil position refers to the surface S12 of the two light rays that enter the extreme end position on the local bus cross section on the imaging surface of the imaging device 6 through the center of the diaphragm 2 and enter the surface S12. This is a position obtained by projecting an intersection of rays extending in the direction of the exit pupil S onto the visual axis. When the lower limit of the expression (7) is exceeded, the imaging optical system becomes large. If the upper limit of the expression (7) is exceeded, even if the imaging field angle of the imaging optical system and the display field angle of the display optical system are the same, the deviation that occurs when a short-distance object is imaged becomes large.

  In addition, for example, by shifting the timing of image display on the display unit and capturing of the external image of the image sensor, noise on the image sensor can be removed so that light from the display unit does not appear on the image sensor. Is possible.

  In the present embodiment, by configuring as described above, a compact and wide-field composite display device, an imaging optical system suitable for the composite display device, and an optical element (first optical element) constituting the imaging optical system ) And the composite lens group 3 are easily provided.

[Numerical example]
Numerical examples 1 to 5 of the present invention are shown below. In each numerical example, the display optical system has the numerical values shown in Table 1.

  The configuration of the imaging optical system of each numerical example is as shown in Tables 2-6.

  In Table 1, the position in the global coordinate system with the position of the exit pupil S as the origin (0, 0, 0) is represented by x, y, z, and the rotation angle (°) around the x axis.

  Tables 2 to 6 show the positions (x, g) of the surface vertices on the S2 surface local coordinates up to the S5 surface according to the local coordinates of the S2 surface (x, y, z coordinate system defining the function of the S2 surface). , Z) and the rotation angle of each surface local coordinate axis about the x-axis (counterclockwise is positive), and the surface spacing d (in the z-axis direction of the S5-surface local coordinate system) The distance to the next surface is indicated by (distance between surfaces). Therefore, the relative position (x, y, z) with respect to the S2 surface local coordinates of each surface vertex after the S6 surface is omitted.

  Further, in the plane Si after the S6 plane, the rotation angle around the x axis of the z axis of each plane local coordinate system with respect to the z axis of the Si-1 plane local coordinate is a, and the Si plane is relative to the Si-1 plane. Not inclined. That is, a is omitted in the case of a coaxial.

  In the other symbols in the table, type indicates a surface shape type, FFS indicates a non-rotation symmetric surface, SPH indicates a spherical surface, and ASP indicates a rotation symmetric aspheric surface. s is a surface number, r is a radius of curvature, d is a surface interval, nd and vd are a refractive index and an Abbe number.

The FFS surface has a shape given by the following definition formula.
Z = (1 / R) * (x2 + y2) / (1+ (1- (1 + C1) * (1 / R) 2 * (x2 + y2)) (1/2)) + C5 * (x2 -y2) + C6 * (-1 + 2 * x2 + 2 * y2) + C10 * (-2 * y + 3 * x2 * y + 3 * y3) + C11 * (3 * x2 * y-y3) + C12 * (x4-6 * x2 * y2 + y4) + C13 * (-3 * x2 + 4 * x4 + 3 * y2-4 * y4) + C14 * (1-6 * x2 + 6 * x4-6 * y2 + 12 * x2 * y2 + 6 * y4) + C20 * (3 * y-12 * x2 * y + 10 * x4 * y-12 * y3 + 20 * x2 * y3 + 10 * y5) + C21 * ( -12 * x2 * y + 15 * x4 * y + 4 * y3 + 10 * x2 * y3-5 * y5) + C22 * (5 * x4 * y-10 * x2 * y3 + y5) + C23 * (x6 -15 * x4 * y2 + 15 * x2 * y4-y6) + C24 * (-5 * x4 + 6 * x6 + 30 * x2 * y2-30 * x4 * y2-5 * y4-30 * x2 * y4 + 6 * y6) + C25 * (6 * x2-20 * x4 + 15 * x6-6 * y2 + 15 * x4 * y2 + 20 * y4-15 * x2 * y4-15 * y6) + C26 * (-1 + 12 * x2- 30 * x4 + 20 * x6 + 12 * y2-60 * x2 * y2 + 60 * x4 * y2-30 * y4 + 60 * x2 * y4 + 20 * y6) ...... (8)
It is assumed that the non-designated coefficient is 0 in the table.

  Next, examples of the display optical system and the imaging optical system according to the present invention will be described.

  FIG. 4 is a diagram of a numerical example of the display optical system 101. In Table 1 showing the display optical system 101, s1 constitutes the exit pupil S, and s2 to 5 constitute the surfaces of the second optical element 7. Light from the surface s8 corresponding to the display surface of the display means 8 is used as the exit pupil S. Guided.

  FIG. 5 is a diagram of Numerical Example 1 of the imaging optical system 102. In Table 2 showing the imaging optical system 102, s1 to 4 are surfaces of the first optical element, and surfaces s5 and 6 are dummy glasses representing the deflecting means 4.

  The aperture is s6. The surfaces s7 to s18 are the lens group of the compound lens group 3, the surfaces s7 and 8 are the first non-rotationally symmetric lenses, the surfaces s11 and 12 are the second non-rotationally symmetric lenses, and the surfaces s17 and 18 are the third non-rotationally symmetric lenses. It is a rotationally symmetric lens. The other surfaces are spherical. As can be seen from the table, the surfaces s7 to s17 are coaxial, and only the surface S18 is inclined.

  The surfaces s19 and s20 are filter-type dummy glasses. Light from the outside is imaged on the imaging surface 20 through the first optical element 1, the deflecting means 4, the stop 2, the compound lens group 3, and the filter system 5.

  The surface s3 of FIG. 4 and the surface s2 of FIG. 5 have the same surface shape (however, since the direction of the z axis is reversed, the sign is shown in reverse), and are joined to act as an optical path separating means. .

  FIG. 6 is a diagram of Numerical Example 2 of the imaging optical system 102. Surfaces s1 to s4 in Table 3 showing the imaging optical system 102 of this embodiment are the first optical element 1, and surfaces s5 and s6 are dummy glasses representing the deflecting means 4.

  The diaphragm 2 has a surface s6. Surfaces s7 to s16 are lens surfaces of the compound lens group 3, surfaces s9 and s10 are first non-rotationally symmetric lenses, surfaces s13 and s14 are second non-rotationally symmetric lenses, and surfaces s15 and s16 are third surfaces. It is a non-rotation symmetric lens. The other surfaces are spherical. As can be seen from the table, the surfaces s7 to s15 are coaxial, and only the surface s16 is inclined.

  The surfaces s17 and s18 are filter-type dummy glasses. Light from the outside is imaged on the imaging surface 18 through the first optical element 1, the deflecting means 4, the stop 2, the compound lens group 3, and the filter system 5.

  The surface s3 in FIG. 4 and the surface s2 in FIG. 6 have the same surface shape (however, since the direction of the z axis is reversed, the sign is shown in reverse), and are joined to act as optical path separating means. .

  FIG. 7 is a diagram of Numerical Example 3 of the imaging optical system 102. Surfaces s1 to s4 in Table 4 showing the imaging optical system 102 of the present embodiment are the first optical element 1, and surfaces s5 and s6 are dummy glasses representing the deflecting means 4.

  The diaphragm 2 is s6. Surfaces s7 to s18 are lens surfaces of the compound lens group 3, surfaces s7 and s8 are first non-rotationally symmetric lenses, surfaces s11 and s12 are second non-rotationally symmetric lenses, and s17 and 18 are third non-rotation symmetric lenses. It is a rotationally symmetric lens. The other surfaces are spherical. As can be seen from the table, the surfaces s7 to s17 are coaxial, and only the surface s18 is inclined.

  The surfaces s19 and s20 are filter-type dummy glasses. Light from the outside is imaged on the imaging surface 20 through the first optical element 1, the deflecting means 4, the stop 2, the compound lens group 3, and the filter system 5.

  The surface s3 in FIG. 4 and the surface s2 in FIG. 7 have the same surface shape (however, since the direction of the z-axis is reversed, the sign is shown in reverse), and are joined to act as optical path separating means. .

  FIG. 8 is a diagram of Numerical Example 4 of the imaging optical system 102. Surfaces s1 to s4 in Table 5 showing the imaging optical system 102 of the present embodiment are the first optical element 1, and surfaces s5 and s6 are dummy glasses representing the deflecting means 4.

  The diaphragm 2 is a surface s5. Surfaces s7 to s19 are lens surfaces of the complex lens group 3, surfaces s7 and s8 are first non-rotationally symmetric lenses, and surfaces s18 and s19 are second non-rotationally symmetric lenses.

  The surfaces s11, s12, and s14 are rotationally symmetric aspheric surfaces. The other surfaces are spherical. As can be seen from the table, the surfaces s7 to s18 are coaxial, and only the surface s19 is inclined.

  The surfaces s20 and s21 are filter-type dummy glasses. Light from the outside is imaged on the imaging surface 21 through the first optical element 1, the deflecting means 4, the stop 2, the compound lens group 3, and the filter system 5. The surface s3 in FIG. 4 and the surface s2 in FIG. 8 have the same surface shape (however, since the direction of the z-axis is reversed, the sign is shown in reverse) and are joined to act as an optical path separating means. .

  FIG. 9 is a diagram of Numerical Example 5 of the imaging optical system 102. Surfaces s1 to s4 in Table 6 showing the imaging optical system 102 of this embodiment are the first optical element 1, and surfaces s5 and s6 are dummy glasses representing the deflecting means 4.

  The diaphragm 2 is a surface s5. The surfaces s7 to s20 are lens surfaces of the compound lens group 3, the surfaces s7 and s8 are first non-rotationally symmetric lenses, and the surfaces s19 and s20 are second non-rotationally symmetric lenses.

  The surface s12 is a rotationally symmetric aspheric surface. The other surfaces are spherical. As can be seen from the table, the surfaces s7 to s19 are coaxial and only the surface s20 is inclined.

  The surfaces s21 and s22 are filter-type dummy glasses. Light from the outside is imaged on the imaging surface 22 through the first optical element 1, the deflecting means 4, the stop 2, the compound lens group 3, and the filter system 5.

  The surface s3 in FIG. 4 and the surface s2 in FIG. 8 have the same surface shape (however, since the direction of the z-axis is reversed, the sign is shown in reverse) and are joined to act as an optical path separating means. .

  Each of the configurations is an imaging optical system having a shooting field angle of a horizontal field angle of 47 ° and a vertical field angle of 36 ° with respect to an imaging device having an imaging surface size of 3.6 mm × 2.7 mm.

  FIG. 10 is an explanatory diagram when a binocular head-mounted display is configured by providing a pair of composite display devices CS of the embodiments of the present invention for the left and right eyes of the observer SA.

  In the present invention, for example, if binocular parallax is used as an image to be displayed on a display element, an image observation system capable of stereoscopic viewing can be constructed.

  Of course, a monocular HMD provided with only one unit for both the left and right eyes may be used.

1 is a cross-sectional view illustrating a basic configuration example of a composite display device of the present invention. Explanatory drawing for demonstrating the reference | standard light ray, the local bus-line cross section, the local child line cross section, etc. in the composite display apparatus of this invention. 1 is a perspective view of a basic configuration example of a composite display device of the present invention. 6 is a numerical example of a display optical system of the composite display device of the present invention. FIG. 3 is a cross-sectional view of a main part of Numerical Example 1 of the imaging optical system of the composite display device of the present invention. Sectional drawing of the principal part of Numerical example 2 of the imaging optical system of the composite display device of the present invention. Sectional drawing of the principal part of Numerical example 3 of the imaging optical system of the composite display device of the present invention. Sectional drawing of the principal part of Numerical example 4 of the imaging optical system of the composite display device of the present invention. Sectional drawing of the principal part of Numerical example 5 of the imaging optical system of the composite display device of the present invention. Explanatory drawing of the head mounted display of this invention.

Explanation of symbols

1 First optical element (optical element)
DESCRIPTION OF SYMBOLS 2 Diaphragm 3 Compound lens group 4 Deflection means 5 Filter element 6 Imaging element 7 2nd optical element 8 Display means E Eye of an observer S Pupil BS Optical path separation means 101 Display optical system 102 Imaging optical system 103 See-through optical system

Claims (6)

An optical path separation provided in the optical path, having a display optical system for guiding the light flux from the display means displaying the image information to the observer's eyeball, and an imaging optical system for focusing the light flux from the outside on the image sensor An eyeball optical axis of a light beam incident on an eyeball of an observer of the display optical system by means, or a virtual eyeball optical axis obtained by extending the eyeball optical axis, and an external optical axis of a light beam incident from the outside of the imaging optical system The imaging optical system has a plurality of eccentric reflecting surfaces that are decentered with respect to the incident surface, the exit surface, and the reference ray Ri and have power on the same medium, At least one surface is a combined surface that serves as both a transmission surface and a reflection surface, the light beam incident from the incident surface is reflected by the plurality of eccentric reflection surfaces, the optical path is folded and emitted from the emission surface, and Has a first optical element with negative cross-sectional composite power Composite display device comprising has. The imaging optical system includes at least one non-rotationally symmetric lens having both a non-rotationally symmetric surface and a rotation-symmetrical surface on both surfaces of the lens, and a plurality of rotation-symmetrical lenses. A compound lens group in which the optical axis and the optical axis of the rotationally symmetric lens are all substantially coincident,
2. The composite display device according to claim 1, wherein a light beam from the outside is guided onto the image pickup element by the composite lens group after passing through the first optical element. The local bus section cross-section focal length fypout and the local sub-section cross-section focal length fxpout of the exit surface of the first optical element and the bus section cross-section combined focal length fyp and the sub-section cross-section combined focal length fxp of the optical element 2 (1)
| Fxp / fxpout | <2 (2)
The composite display device according to claim 2, wherein the composite display device is configured to satisfy the following. A local bus cross-section focal length fyl, a local sub-line cross-section fxl of the non-rotationally symmetric surface of the compound lens group, a bus-bar cross-section composite focal length fyg and a sub-line cross-section composite focal length fxg of the compound lens group are:
| Fyg / fyl | <1 (3)
| Fxg / fxl | <1 (4)
The composite display device according to claim 3, wherein the composite display device is configured to satisfy the following. The bus cross-section combined focal length of the entire imaging optical system is fy, the child cross-section combined focal length is fx, the bus cross-section combined focal length of the first optical element is fyp, and the child cross-section combined focal length is fxp. sometimes,
-1 <fy / fyp <0 (5)
-1 <fx / fxp <0 (6)
The composite display device according to claim 4, wherein the composite display device is configured to satisfy the following. The distance from the developed entrance pupil position to the exit pupil position of the display optical system when the entrance pupil of the imaging optical system is developed on the visual axis is Dpp, and the exit pupil of the display optical system from the exit surface of the display optical system When the distance to is er,
0.25 <Dpp / er <8.0 (7)
The composite display device according to claim 5, wherein the composite display device is configured to satisfy the following.