Optical systems and display devices

Abstract

To provide an optical system for display devices with high light utilization efficiency. [Solution] The optical system has an incident section 21 into which light from a display element is incident, a reflecting section 23 that reflects the light from the incident section, and an output section 24 that emits the light from the reflecting section toward the observation area. The reflecting section has a transmissive reflective surface that reflects a portion of the first wavelength range of the emission wavelength range of the display element and transmits light in a second wavelength range other than the first wavelength range. The optical system emits the light in the first wavelength range that has been reflected multiple times by the transmissive reflective surface from the output section.

Description

Technical Field

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[0005]

[0001] The present invention relates to an optical system suitable for image observation.

Background Art

[0002] Some optical systems used in display devices such as smart glasses and AR (Augmented Reality) glasses use a light guide member that propagates light incident from an incident portion inside and emits it from an emission portion toward the observer's eye. Patent Document 1 discloses a light guide as a light guide member for presenting light from a display element as a virtual image to the observer's eye. Patent Document 2 discloses a display device having a combiner that guides light emitted from a display element and guided by a prism as a light guide member and light from the outside to the observer's eye at the same time, and the combiner has a characteristic of selectively reflecting only light within a specific wavelength range. [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​One aspect of the present invention is an optical system comprising an incident section into which light from a display element is incident, a reflecting section that reflects the light from the incident section, and an output section that emits the light from the reflecting section toward an observation area. The reflecting section includes a transmissive reflective surface that reflects light in a first wavelength range within a portion of the emission wavelength range of the display element and transmits light in a second wavelength range other than the first wavelength range, and is characterized in that the light in the first wavelength range that has been reflected multiple times by the transmissive reflective surface is emitted from the output section. A display device having the above optical system also constitutes another aspect of the present invention. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an optical system with high light utilization efficiency for use in a display device. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram shows the configuration of the display device in Example 1. [Figure 2] This diagram illustrates the optical path of the display device in Example 1. [Figure 3] This figure shows the solar spectrum and the reflection spectrum of the extraction mirror in Example 1. [Figure 4] This figure shows the reflection characteristics of the extraction mirror with respect to the emission spectrum of the display element in Example 1. [Figure 5] This figure shows the configuration of the display device in Example 2. [Figure 6] This figure shows the reflection characteristics of the extraction mirror with respect to the emission spectrum of the display element in Example 2. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Examples]

[0009] Figure 1 shows the configuration of the display device 100 of Embodiment 1. The display device 100 is a so-called near-eye display, such as smart glasses, AR glasses, and a head-mounted display (HMD), which is placed in front of the observer's eyes 30.

[0010] The display device 100 includes a projection unit 10 and an optical system including a light guide plate (light guide member) 20. In the following description, the horizontal direction (for example, the direction from the observer's left eye to the right eye) is defined as the X-axis direction (first direction), the vertical direction as the Y-axis direction (second direction), and the direction perpendicular to the X-axis and Y-axis direction (the direction from the observer's eye 30 to the light guide plate 20) is defined as the Z-axis direction.

[0011] The projection unit 10 includes a display element 11 such as an OLED (Organic Light Emitting Diode) and a projection optical system 12 that projects light emitted from the display element 11 toward the light guide plate 20.

[0012] The light guide plate 20 is configured to form a pupil EPc conjugate to the exit pupil EP of the projection optical system 12 at the position of the observer's eye 30 in a one-dimensional direction (for example, the X-axis direction). This allows the image light emitted from the projection unit 10 to be efficiently guided to the observer's eye 30.

[0013] Figure 2(a) shows the display device 100 viewed from an oblique angle, and Figure 2(b) shows a cross-section of the display device 100. These figures also show the optical path of the image light. The divergent luminous flux, which is the image light emitted from the display element 11, is converted into a parallel luminous flux by the projection optical system 12. The parallel luminous flux passes through the incident portion 21 of the light guide plate 20 and enters the interior of the light guide plate 20. At this time, the divergent luminous flux emitted from the entire effective area of ​​the display element 11 passes through the projection optical system 12, forming image light that contributes to image display across the entire field of view.

[0014] The image light emitted from the projection optical system 12 forms the exit pupil EP described above near the entrance portion 21 of the light guide plate 20. At the exit pupil EP, image light from the entire angular field of view converges and enters the light guide plate 20. The image light that enters the light guide plate 20 from the projection optical system 12 propagates inside the light guide plate 20 while undergoing internal reflection (total reflection) on the inner surface, and enters the folding mirror 22 of the light guide plate 20.

[0015] The image light that enters the folding mirror 22 is reflected and deflected by the folding mirror 22, and then further travels toward the exit portion 24 provided on the light guide plate 20. The image light that has undergone internal reflection at the exit portion 24 enters the extraction mirror 23, which is an optical element that forms a reflecting portion disposed inside the light guide plate 20 so as to face obliquely with respect to the exit portion 24. The extraction mirror 23 reflects a part of the incident image light and emits it from the exit portion 24 to the outside of the light guide plate 20. The image light thus emitted to the outside of the light guide plate 20 travels toward the EMB (Eye Motion Box) 31, which is an observation region where the observer's eye 30 is disposed. Also, the extraction mirror 23 transmits the image light other than the part that is reflected among the image light from the display element 11 and the light from the outside world (light other than the light from the display element: hereinafter referred to as external light) on the side opposite to the EMB 31.

[0016] As the extraction mirror 23, a right-angle mirror array is used, which is configured by arranging a plurality of right-angle mirrors each composed of two (paired) transmissive-reflective surfaces that are planar and arranged so as to form an angle (here, 90°) with each other. A part of the image light that is reflected by the folding mirror 22 and travels inside the light guide plate 20 is reflected by one of the transmissive-reflective surfaces of the right-angle mirror, and then reflected by the other transmissive-reflective surface of the same right-angle mirror and emitted from the exit portion 24 to the outside of the light guide plate 20. The image light emitted from the light guide plate 20 overlaps at the EMB 31 that is at a predetermined distance from the light guide plate 20 to form the pupil EPc.

[0017] Note that the angle formed by the pair of transmissive-reflective surfaces may be other than 90°, and the angles formed by each of the plurality of pairs of transmissive-reflective surfaces with each other may vary within the extraction mirror.

[0018] On the other hand, the image light that has passed through without being reflected by any of the right-angled mirrors of the extraction mirror 23 propagates through the light guide plate 20, is internally reflected at the exit portion 24, and enters another right-angled mirror of the extraction mirror 23 again. As a result, a plurality of light beams as image light are emitted from the light guide plate 20 toward the EMB 31 while being replicated. Further, as indicated by the dashed arrow in Fig. 2(b), a part of the external light passes through the light guide plate 20 (extraction mirror 23) and is emitted to the EMB side.

[0019] Here, in a situation where an observer wears a near-eye display in front of the eyes and makes eye contact with a person facing the observer across the light guide plate, it is desirable that the presence of the extraction mirror in the light guide plate is not conspicuous. For this reason, a high transmittance is required as the transmission characteristic of the extraction mirror. That is, it is required that the amount of reflected light from the extraction mirror when external light is incident is small, and it is difficult for the person facing to notice the presence of the extraction mirror. Also, when an observer wearing a near-eye display looks at the outside world, it is less likely that the observer will feel the extraction mirror in front of the eyes as a foreign object if the transmittance of the extraction mirror is high. As a result, good see-through observation of the outside world becomes possible.

[0020] For this purpose, for example, it is preferable that the transmittance of the extraction mirror is 70% or more and the reflectance is 30% or less, and more preferably, the transmittance of the extraction mirror is 80% or more and the reflectance is 20% or less.

[0021] However, if the reflection characteristic of the extraction mirror is a low reflectance as described above, the amount of light reflected by the extraction mirror among the image light that has propagated through the light guide plate decreases. Particularly, in a configuration in which the image light is reflected twice by a low-reflectance extraction mirror and emitted to the outside of the light guide plate, the amount of light emitted from the light guide plate toward the EMB decreases and the light utilization efficiency decreases.

[0022] Therefore, in this embodiment, the characteristics of the extraction mirror 23 are set such that only light of a part of the spectra included in each color channel is reflected at a high reflectance (for example, 80% or more), and light of other spectra is transmitted at a high transmittance (for example, 80% or more).

[0023] This setting will be explained using Figure 3. Figure 3 shows the spectrum 40 of sunlight as ambient light in the visible light region (400 nm to 700 nm) and the spectra 51 to 53 of the light reflected by the extraction mirror 23. The horizontal axis represents wavelength (nm), and the vertical axis represents light intensity. Sunlight has a continuous spectrum that is evenly distributed throughout the visible light region. Here, we define the spectrum constituting the red channel of sunlight as 590 nm to 700 nm, the spectrum constituting the green channel as 490 nm to 590 nm, and the spectrum constituting the blue channel as 400 nm to 490 nm.

[0024] The extraction mirror 23 is configured to have reflective properties that produce spectrum 51 in the red channel, spectrum 52 in the green channel, and spectrum 53 in the blue channel. Specifically, the extraction mirror 23 has the characteristic of reflecting light of wavelengths 640±3nm (peak wavelength λ=640nm), 530±3nm (peak wavelength λ=530nm), and 460±3nm (peak wavelength λ=460nm), respectively, which are the first wavelength ranges. The full width at half maximum (FWHM) for each of the first wavelength ranges is 6nm. The extraction mirror 23 also has the characteristic of transmitting light of the second wavelength ranges other than the first wavelength ranges.

[0025] Because the spectrum of sunlight is evenly distributed across the red, green, and blue channels, even if a small portion of the spectrum in each channel (for example, a full width at half maximum of 6 nm) is missing, there is no significant change in how colors appear. Similarly, the extraction mirror 23 transmits light in the second wavelength range other than 640±3 nm, 530±3 nm, and 460±3 nm, that is, most of the wavelengths of light in the red, green, and blue channels that are incident on the light guide plate 20 from the outside. As a result, high transmittance for light in each channel can be achieved. Specifically, transmittance of 90% or more can be achieved in the second wavelength range.

[0026] The reflective and transmissive surface of the extraction mirror 23 having the characteristics described above is made of, for example, a dielectric multilayer film.

[0027] By using such a removable mirror 23, a person facing an observer (wearer) wearing a near-eye display in front of their eyes can observe the wearer's eyes with high light transmission, making it easier to make eye contact. In addition, the wearer can observe the outside world in front of them in a brighter light.

[0028] According to the display device 100 of this embodiment, the see-through characteristics for the wearer can be improved, and the take-out mirror 23 inside the light guide plate 20 can be made less visible from the outside, making it easier to see the wearer's eyes and thus facilitating eye contact with the person facing the wearer.

[0029] Figure 4 shows the relationship between the emission spectra (spectrums of light incident on the extraction mirror 23) 41-43 of the display element 11 in this embodiment and the spectra 51-53 of light reflected by the extraction mirror 23. The horizontal axis represents wavelength (nm), and the vertical axis represents light intensity. The OLED display element 11 emits image light having an emission spectrum 41 for the red channel, an emission spectrum 42 for the green channel, and an emission spectrum 43 for the blue channel. Specifically, the emission spectra are as follows: red channel: emission wavelength range 640±20nm (peak wavelength λr=640nm), green channel: emission wavelength range λg=530±17nm (peak wavelength λg=530nm), blue channel: emission wavelength range λb=460±13nm (peak wavelength λb=460nm). The width of the emission wavelength range for each channel corresponds to the full width at half maximum.

[0030] On the other hand, similar to Figure 3, the extraction mirror 23 reflects light from the red channel spectrum 51, the green channel spectrum 52, and the blue channel spectrum 53. The pairs of transmission reflective surfaces of the multiple right-angle mirrors that make up the right-angle mirror array, which is the extraction mirror 23, have the same reflection characteristics (and the same transmission characteristics) to each other. That is, the pairs of transmission reflective surfaces reflect light at wavelengths of 640 nm ± 3 nm, 530 nm ± 3 nm, and 460 nm ± 3 nm, which are part of the emission wavelength range of the display element 11 as the first wavelength range. Light in these first wavelength ranges represents a small portion (e.g., less than 30%) of the amount of light emitted from the display element 11. Specifically, it represents light corresponding to 15% of the amount of light emitted from the red channel, 18% of the amount of light emitted from the green channel, and 23% of the amount of light emitted from the blue channel.

[0031] Furthermore, the characteristics of at least one pair of transmission-reflective surfaces among multiple pairs of transmission-reflective surfaces may differ from the characteristics of the other pairs of transmission-reflective surfaces.

[0032] Light propagating within the light guide plate 20 is reflected by the pair of transmissive reflective surfaces (first and second transmissive reflective surfaces) in each right-angle mirror of the extraction mirror 23 and exits to the outside of the light guide plate 20. At the first transmissive reflective surface, where the light is first reflected, only the light from spectra 51 to 53 of the light from emission spectra 41 to 43 of the display element 11 is reflected. Therefore, the reflected light ratio, which is the ratio of reflected light to light in the emission spectrum, is low. Specifically, the reflectance of each channel of the first transmissive reflective surface (assuming 85% here) is multiplied by the reflectance of each channel corresponding to spectra 51 to 53 (15% for the red channel, 18% for the green channel, and 23% for the blue channel), resulting in a reflected light ratio of 13% for the red channel, 15% for the green channel, and 20% for the blue channel.

[0033] On the other hand, the second transmissive reflective surface, which reflects the light reflected by the first transmissive reflective surface, reflects all of the spectrum reflected by the first transmissive reflective surface, thus increasing the reflected light intensity ratio. Specifically, in each channel, the light intensity ratio of the light reflected by the second transmissive reflective surface to the light reflected by the first transmissive reflective surface is 100%, multiplied by the reflectance of each channel of the second transmissive reflective surface (85%), resulting in a reflected light intensity ratio of 85% at the second transmissive reflective surface. In other words, the reflected light intensity ratio when light is reflected twice by the first and second transmissive reflective surfaces is 11% for the red channel, 13% for the green channel, and 17% for the blue channel.

[0034] This reflected light ratio is higher than the 9% ratio obtained when light is reflected twice by a transmissive reflective surface with a transmittance of 70% and a reflectance of 30%, as mentioned above. It is also more than twice as high as the 4% ratio obtained when light is reflected twice by a transmissive reflective surface with a transmittance of 80% and a reflectance of 20%. Furthermore, it is more than 11 times higher than the 1% ratio obtained when light is reflected twice by a transmissive reflective surface with a transmittance of 90% and a reflectance of 10%.

[0035] Thus, the extraction mirror 23 of this embodiment achieves high transmittance to natural light from the outside while allowing light propagating within the light guide plate 20 to be emitted towards the EMB 31 without significantly reducing the amount of light after two reflections, thereby achieving high light utilization efficiency. [Examples]

[0036] Figures 5(a) and 5(b) show the configuration of the display device 100' of Example 2. Figure 5(a) shows the display device 100' viewed from an oblique angle, and Figure 5(b) shows a cross-section of the display device 100'. The optical path of the image light is also shown in these figures.

[0037] The display device 100' of this embodiment differs from Embodiment 1 in that the extraction mirror 23' provided within the light guide plate 20' is composed of three right-angle mirror arrays 231, 232, and 233. By composing the extraction mirror 23' with three right-angle mirror arrays 231 to 233 arranged vertically (in the X-axis direction), the light guide plate 20' is made thinner compared to Embodiment 1. In this configuration, light that enters the light guide plate 20' from the projection unit 10 and propagates inside is reflected by the three right-angle mirror arrays 231 to 233, so that image light with the entire vertical field of view is incident on the EMB 31.

[0038] Furthermore, as shown by the dashed arrow in Figure 5(b), some of the ambient light passes through the light guide plate 20' (extraction mirror 23') and exits to the EMB side.

[0039] Figures 6(a) to 6(c) show the relationship between the emission spectra 41 to 43 (spectrums of light incident on the extraction mirror 23') of the display element 11 in this embodiment and the spectra 51 to 53 of light reflected by the extraction mirror 23'. The horizontal axis represents wavelength (nm), and the vertical axis represents light intensity. Similar to Figure 4, the display element 11 emits the emission spectrum 41 in the red channel, the emission spectrum 42 in the green channel, and the emission spectrum 43 in the blue channel. The specific emission spectra are the same as in Embodiment 1.

[0040] The three right-angle mirror arrays 231, 232, and 233 that constitute the extraction mirror 23' are set so that their reflection characteristics in their respective three channels are different from each other. In other words, the first reflection wavelength range, which is the first wavelength range reflected by the first right-angle mirror array 231, the second reflection wavelength range, which is the first wavelength range reflected by the second right-angle mirror array 232, and the third reflection wavelength range, which is the first wavelength range reflected by the third right-angle mirror array 233 are all different from each other. Note that, as said here, the first to third reflection wavelength ranges being different from each other means that their peak wavelengths are different from each other, and there is no overlap between the wavelength ranges, or there is a partial overlap between the wavelength ranges.

[0041] As shown in Figure 6(a), the first right-angle mirror array 231 has a first reflection characteristic that reflects light from the red channel spectrum 511, the green channel spectrum 521, and the blue channel spectrum 531. Specifically, the first right-angle mirror array 231 reflects light from wavelengths of 640±3nm, 530±3nm, and 460±3nm, which are part of the emission wavelength range of the display element 11 and constitute a first reflection wavelength range.

[0042] As shown in Figure 6(b), the second right-angle mirror array 232 has a second reflection characteristic that reflects light from the red channel spectrum 512, the green channel spectrum 522, and the blue channel spectrum 532. Specifically, the second right-angle mirror array 232 reflects light from wavelengths 632±3nm, 522±3nm, and 452±3nm, which are part of the emission wavelength range of the display element 11 and constitute a second reflection wavelength range.

[0043] As shown in Figure 6(c), the third right-angle mirror array 233 has a third reflection characteristic that reflects light from the red channel spectrum 513, the green channel spectrum 523, and the blue channel spectrum 533. Specifically, the third right-angle mirror array 233 reflects light from wavelengths 648±3nm, 538±3nm, and 468±3nm, which are part of the emission wavelength range of the display element 11 and constitute a third reflection wavelength range.

[0044] Furthermore, each right-angle mirror array has the characteristic of transmitting light in the second wavelength range, which is outside the first to third reflection wavelength ranges.

[0045] Of the light propagating within the light guide plate 20', the light in the first reflection wavelength range is reflected twice by the pair of transmission and reflection surfaces of the first right-angle mirror array 231, and then exits from the exit section 24 of the light guide plate 20' to reach the EMB 31.

[0046] Furthermore, of the light propagating within the light guide plate 20', the light in the second and third reflection wavelength ranges is transmitted through the first right-angle mirror array 231. Of this, the light in the second reflection wavelength range is reflected twice by the pair of transmissive reflective surfaces of the second right-angle mirror array 232, which is located downstream of the first right-angle mirror array 231 in the optical path, and is emitted from the exit section 24 of the light guide plate 20' to reach the EMB 31. Note that some of the light incident on the second right-angle mirror array 232 includes light that has been transmitted through the first right-angle mirror array 231. However, since the second reflection wavelength range reflected by the second right-angle mirror array 232 is different from the first reflection wavelength range reflected by the first right-angle mirror array 231, there is no significant loss of light intensity in the light reflected by the second right-angle mirror array 232.

[0047] Light in the third reflection wavelength range that has passed through the first and second right-angle mirror arrays 231 and 232 is reflected twice by the pair of transmitting and reflecting surfaces of the third right-angle mirror array 233, which is located downstream of the second right-angle mirror array 232 in the optical path, and exits from the exit section 24 of the light guide plate 20' to reach the EMB 31. Note that some of the light incident on the third right-angle mirror array 233 includes light that has passed through the first and second right-angle mirror arrays 231 and 232. However, since the third reflection wavelength range reflected by the third right-angle mirror array 233 is different from the first and second wavelength reflection ranges reflected by the first and second right-angle mirror arrays 231 and 232, there is no significant loss of light intensity in the light reflected by the third right-angle mirror array 233.

[0048] By making the wavelength ranges reflected by each of the multiple right-angle mirror arrays 231-233 different from each other, the light utilization efficiency can be improved while making the light intensity distribution of the light reflected by the multiple right-angle mirror arrays 231-233 (extracted outside the light guide plate 20') uniform. Furthermore, because the transmittance of each right-angle mirror array is high, it is difficult for a person facing the wearer to see the structure of each right-angle mirror array, and it does not interfere with eye contact between the wearer and the person facing them.

[0049] The combiner used in the display device disclosed in Patent Document 2 above reflects only a portion of the wavelength range of light from the display element once and guides it to the observer's eye. In contrast, the display devices of the above embodiments are based on a configuration that reflects only a portion of the wavelength range of light from the display element multiple times and guides it to the observer's eye, thereby improving light utilization efficiency while maintaining good see-through characteristics and eye contact.

[0050] In each embodiment, the case described was that the light guide plates 20 and 20' emit light that has been reflected twice by the two transmissive reflective surfaces of the extraction mirrors 23 and 23' toward the EMB 31. However, the light guide plates may be configured so that the reflection at the extraction mirror occurs three or more times by three or more transmissive reflective surfaces. Alternatively, the extraction mirrors may be configured using curved transmissive reflective surfaces, so that light that has been reflected multiple times by a single transmissive reflective surface is emitted toward the EMB 31.

[0051] The above embodiments include the following configuration.

[0052] (Composition 1) It has an incident section into which light from a display element is incident, a reflecting section that reflects the light from the incident section, and an output section that emits the light from the reflecting section toward the observation area. The reflective portion includes a transmissive reflective surface that reflects light in a first wavelength range within a portion of the emission wavelength range of the display element and transmits light in a second wavelength range other than the first wavelength range. An optical system characterized by emitting light in the first wavelength range, which has been reflected multiple times by the transmission and reflection surface, from the emission unit. (Configuration 2) The reflective portion has a plurality of the transmissive reflective surfaces, The optical system according to configuration 1, characterized in that light in the first wavelength range that has been reflected multiple times by the multiple transmissive reflective surfaces is emitted from the emission unit. (Composition 3) The optical system according to configuration 2, characterized in that the characteristics of the plurality of transmissive and reflective surfaces are the same to each other. (Composition 4) The display element emits light in multiple emission wavelength ranges, The optical system according to any one of configurations 1 to 3, characterized in that the transmitted reflective surface has the property of reflecting light in the first wavelength range, which is a part of each of the plurality of emission wavelength ranges. (Composition 5) The display element emits light in multiple emission wavelength ranges, The light guide member comprises a plurality of reflective portions, The optical system according to configuration 1, characterized in that the first wavelength range, which is a part of each of the multiple emission wavelength ranges in the multiple reflecting portions, is different from each other. (Composition 6) The optical system according to configuration 2, characterized in that the plurality of transmissive reflective surfaces in the reflective section are arranged at angles to each other. (Composition 7) The optical system according to any one of configurations 1 to 6, characterized in that the reflectance of the transmitted reflective surface in the first wavelength range is 80% or more. (Composition 8) The optical system according to any one of configurations 1 to 7, characterized in that the transmittance of the transmissive reflective surface in the second wavelength range is 80% or more. (Composition 9) The optical system according to any one of configurations 1 to 8, characterized in that the reflective portion reflects light in the first wavelength range that accounts for 30% or less of the light in the first and second wavelength ranges incident from the display element. (Composition 10) The optical system according to any one of configurations 1 to 9, characterized in that the reflective portion transmits light in the second wavelength range other than the light from the display element, which is incident from the outside world on the opposite side of the observation area, toward the observation area. (Composition 11) The optical system described in any one of configurations 1 to 10, A display device characterized by having the aforementioned display element.

[0053] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of Symbols]

[0054] 100,100′ display device 11 Respect Display 20,20′ light guide plate 21 Input part 22 Ejection section 23,23′ Take-out mirror

Claims

1. The incident section into which light from the display element enters, A reflecting part that reflects light from the incident part, It has an emission unit that emits light from the reflective unit toward the observation area, The reflective portion includes a transmissive reflective surface that reflects light in a first wavelength range within a portion of the emission wavelength range of the display element and transmits light in a second wavelength range other than the first wavelength range. An optical system characterized by emitting light in the first wavelength range, which has been reflected multiple times by the transmission and reflection surface, from the emission unit.

2. The reflective portion has a plurality of the transmissive reflective surfaces, The optical system according to claim 1, characterized in that light in the first wavelength range that has been reflected multiple times by the multiple transmissive reflective surfaces is emitted from the emission unit.

3. The optical system according to claim 2, characterized in that the characteristics of the plurality of transmissive and reflective surfaces are the same to each other.

4. The display element emits light in multiple emission wavelength ranges, The optical system according to claim 1, characterized in that the transmitted reflective surface has the property of reflecting light in the first wavelength range, which is a part of each of the plurality of emission wavelength ranges.

5. The display element emits light in multiple emission wavelength ranges, The system includes multiple reflective sections, The optical system according to claim 1, characterized in that the first wavelength range, which is a part of each of the plurality of emission wavelength ranges in the plurality of reflecting portions, is different from each other.

6. The optical system according to claim 2, characterized in that the plurality of transmissive reflective surfaces, each being a plane, are arranged at an angle to one another in the reflective portion.

7. The optical system according to claim 1, characterized in that the reflectance of the transmitted and reflected surface in the first wavelength range is 80% or more.

8. The optical system according to claim 1, characterized in that the transmittance of the transmissive reflective surface in the second wavelength range is 80% or more.

9. The optical system according to claim 1, characterized in that the reflective portion reflects light in the first wavelength range that accounts for 30% or less of the light in the first and second wavelength ranges incident from the display element.

10. The optical system according to claim 1, characterized in that the reflective portion transmits light in the second wavelength range other than the light from the display element, which is incident from the outside world on the opposite side of the observation area, toward the observation area.

11. An optical system according to any one of claims 1 to 10, A display device characterized by having the aforementioned display element.

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