TWI470272B - Image display device - Google Patents

Description

Image display device

The present invention relates to an image display device, and more particularly to a head mounted image display device.

The head mounted image display device is a device for displaying images and colors. Usually in the form of an eye mask or helmet, the display screen is placed close to the user's eyes, and the focal length is adjusted by the optical path to project a picture to the eye at a close distance. With the rapid development of technology, head-mounted image display devices have expanded to medical applications in addition to recreational use. Patients with amblyopia and those wearing artificial retinas can view external images by wearing such an image display device.

Further, the image capturing device is used to capture an image of the outside world, and the image is processed by the IC chip to form a digital or analog signal, and the signals are provided to the display electrically connected to the image capturing device. An image light is then output by the display and projected into the eye of a person with amblyopia or a person wearing an artificial retina. The band of the image light received by the amblyopia patient is a band of visible light, and the band of the image light received by the person wearing the artificial retina is a band of infrared light.

In general, an image display device is mainly composed of a plurality of lenses. However, the lens has a different refractive index for light of different wavelengths, so that chromatic aberration occurs when light of different wavelengths passes through the lens. At this stage, the technology is mainly through diffractive components or multiple The design of the mirror improves the phenomenon of chromatic aberration. However, if both amblyopia patients and blind people (persons wearing artificial retinas) are allowed to view images at the same time, the image display device must be able to solve the chromatic aberration in the visible to infrared light bands, and the current technology cannot be achieved. In addition, there are not many materials that infrared light can penetrate, so the choice of materials is narrower.

The present invention provides an image display device that allows an amblyopic patient and a blind person to view an image.

The present invention provides an image display device that is adapted to be placed in front of a single eye of a user. The image display device includes a display, a first mirror and a second mirror. The display outputs an image light. The first mirror is located on the transmission path of the image light. The first mirror is adapted to reflect image light. The second mirror is located on the transmission path of the reflected image light and is located outside the transmission path between the display and the first mirror. Both ends of the second mirror are adjacent to the display and the first mirror, respectively. The first mirror reflects the image light to the second mirror, and the second mirror further transmits the image light to the user's eye.

In an embodiment of the invention, the ratio of the focal length of the first mirror to the focal length of the second mirror is between 1.4 and 2.4.

In an embodiment of the invention, the image display device has a focal length (f-number) between 1 and 10.

In an embodiment of the invention, the image display device has a focal ratio between 3 and 10.

In an embodiment of the invention, the first mirror and the second mirror are at an angle of between 35 degrees and 70 degrees.

In one embodiment of the invention, the aforementioned angle is 55 degrees.

In an embodiment of the invention, the first mirror has a first reflecting surface, and the second mirror has a second reflecting surface, and the first reflecting surface and the second reflecting surface are curved surfaces.

In an embodiment of the invention, the area of the first mirror is substantially equal to the area of the second mirror.

In an embodiment of the invention, the image light is visible light or infrared light.

In an embodiment of the invention, the image display device further includes an image capturing device. The image capturing device is electrically connected to the display. The image capture device is adapted to capture an image and provide an image to the display to cause the display to output image light.

Based on the above, the first mirror and the second mirror can transmit the image light outputted by the display to the user's eyes in a reflective manner, thereby solving the aforementioned chromatic aberration phenomenon, and can also be applied to visible light to The infrared band system allows the amblyopic patient and the blind person to view the image.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a schematic diagram of an image display device according to an embodiment of the present invention. please Referring to FIG. 1 , the image display device 100 of the present embodiment is adapted to be disposed in front of a single eye U of a user. The image display device 100 includes a display 110 , a first mirror 120 , and a second mirror 130 .

The display 110 outputs an image light L1. The display 110 can be a Digital Micromirror Device (DMD), a Liquid Crystal on Silicon (LCoS), an Organic Light-Emitting Diode (OLED), or a light-emitting diode array. (LED array) display device, IR array display device or any other suitable micro display device. The wavelength band (i.e., the wavelength range) of the image light L1 may vary depending on the image display device 100 applying a different display 110. For example, when the display 110 is a light-emitting diode array display device, the image light L1 outputted by the display device is visible light. When the display 110 is an infrared light array display device, the image light L1 outputted by the display device is infrared light.

The first mirror 120 is located on the transmission path of the image light L1. The second mirror 130 is located on the transmission path of the reflected image light L2, and the second mirror 130 is located further in a region other than the transmission path between the display 110 and the first mirror 120. In other words, the second mirror 130 is not located on the transmission path between the display 110 and the first mirror 120.

The image display device 100 of the present embodiment can prevent the image light L1 outputted by the display 110 from being blocked by the second mirror 130, and can be avoided by the second mirror 130 being disposed outside the transmission path of the image light L2. The image light is disturbed by the shield to generate noise. Therefore, most of the image light L1 outputted by the display 110 will be successively first. The mirror 120 and the second mirror 130 are reflected and transmitted to the single eye U of the user. Therefore, the image display device 100 of the present embodiment can have good display quality in addition to good brightness.

In the embodiment, the image display device 100 further includes a frame 140 to provide the bearing surface 110, the first mirror 120 and the second mirror 130. The frame 140 may have an opening V for transmitting the image light L3 reflected by the second mirror 130 to the single eye U of the user. The diameter D of the opening V can be adjusted according to actual needs, wherein the larger the diameter D, the more image light L3 the single eye U can receive.

In the present embodiment, the frame 140 is exemplified by a quadrangular hollow frame. However, the present invention does not limit the shape of the frame 140, and does not limit the display 110 and the first mirror 120 disposed on the frame 140. And the shape of the second mirror 130, the shape of the aforementioned components may be determined according to actual needs. For example, in other embodiments, the frame 140 may be a polygon, and the display 110, the first mirror 120, and the second mirror 130 disposed on the frame 140 may also be polygonal, circular, or rectangular. .

In addition, the frame 140 has an inner surface S, and the display 110, the first mirror 120, and the second mirror 130 are disposed on three sides of the inner surface S of the frame 140, for example. In the present embodiment, the display 110 and the first mirror 120 are disposed on opposite sides of the inner surface S, for example, and the second mirror 130 and the opening V are respectively disposed on opposite sides of the inner surface S. In addition, two ends of the second mirror 130 are adjacent to one end of the display 110 and one end of the first mirror 120, wherein the first mirror 120 and the second mirror 130 are at an angle θ, and the angle θ can be between 35 degrees. To 70 Between degrees, and the angle θ is preferably 55 degrees. By designing the angle θ and by placing the display 110 beside the opening V, stray light can be prevented from entering the single eye U of the user, thereby obtaining better imaging quality.

In the present embodiment, the area A120 of the first mirror 120 may be designed to be substantially equal to the area A130 of the second mirror 130. In addition, the first mirror 120 has a first reflecting surface S1 adapted to reflect the image light L1 output by the display 110. The second mirror 130 has a second reflecting surface S2 adapted to reflect the image light L2 reflected by the first reflecting surface S1.

Further, the first reflecting surface S1 and the second reflecting surface S2 are curved surfaces. The curved surface refers to a free curved surface that does not have a spherical center. In other words, the first reflecting surface S1 and the second reflecting surface S2 have no symmetrical optical axes. When the first reflecting surface S1 (or the second reflecting surface S2) is actually simulated, an asymmetrical line may be added by a formula of a spherical surface (having a symmetrical optical axis) to modulate the first reflecting surface S1 (or the second reflecting surface) S2) Curvature at different locations, thereby eliminating other aberrations and optimizing the image quality of the image display device 100.

The focal length of the first mirror 120 is, for example, between 50 millimeters (mm) and 60 mm, and the focal length of the second mirror 130 is, for example, between 85 mm and 120 mm. In other words, the ratio of the focal length of the first mirror 120 to the focal length of the second mirror 130 is between 1.4 and 2.4. In the present embodiment, the focal length of the first mirror 120 is, for example, 55 mm, and the focal length of the second mirror 130 is, for example, 84 mm.

In addition, the focal length (f-number) of the image display device 100 of the present embodiment is, for example, between 1 and 10. The focal ratio refers to an effective focal length (EFL) of the image display device 100 (Effective Focal Length, EFL) The ratio to the diameter D. When the focal ratio is increased, the diameter D needs to be small, which tends to cause insufficient brightness of the image display device 100. When the focal ratio becomes smaller, the area of the first mirror 120 and the second mirror 130 needs to be increased. That is to say, when the focal ratio becomes smaller, it is necessary to increase the size of the image display device 100, which is liable to cause a burden on the user when wearing. Therefore, in the embodiment, the focus of the image display device 100 is preferably between 3 and 10.

The image display device of the prior art requires a plurality of lenses or cymbals to transmit image light to the eyes of the user and to reduce chromatic aberration. In contrast, the image display device 100 of the present embodiment can transmit the image light L1 to the single eye U of the user by two mirrors (refer to the first mirror 120 and the second mirror 130). Therefore, in addition to saving the number of lenses required, the image display device 100 of the present embodiment can also have a small volume and be lighter, so that the user wears less burden. In addition, since the present embodiment transmits the image light L1 in a reflective manner, the phenomenon of chromatic aberration of the prior art can be solved, and the system can be applied to the visible light to infrared light band. Therefore, the image display device 100 of the present embodiment allows an amblyopic patient and a blind person to view an image.

The image viewed by the image display device 100 of the foregoing embodiment is an untimely image. Non-timely images here are preset (or pre-recorded) images, rather than real-world images around the user. However, in other embodiments, the image display device can also be designed to allow amblyopia patients and the blind person to view timely images. 2 is a schematic diagram of an image display device according to another embodiment of the present invention.

Referring to FIG. 2, the image display device 200 of the embodiment is in FIG. The image display device 100 has similar components. The main difference between the two is that the image display device 200 further includes an image capturing device 150. The image capturing device 150 can be a camera, a camera, or any device suitable for capturing images.

The image capturing device 150 is electrically connected to the display 110. In this embodiment, the image capturing device 150 may be electrically connected to the display 110 through a wire, but the invention is not limited thereto. The image capturing device 150 is adapted to capture an image and provide an image to the display 110 to cause the display 110 to output the image light L1. Therefore, the amblyopia patient and the blind person can view the timely image through the image display device 200.

The image display device 200 also has the above-described effects of the image display device 100. In short, the image display device 200 can transmit the image light L1 to the single eye U of the user by two mirrors (refer to the first mirror 120 and the second mirror 130). Therefore, compared with the design of the multilayer lens of the prior art, the image display device 200 of the present embodiment is relatively light, and thus allows the user to wear less when wearing. In addition, since the embodiment transmits the image light L1 in a reflective manner, the phenomenon of chromatic aberration of the prior art can be improved, and the system can be applied to the visible light to the infrared light, thereby allowing the amblyopia patient and the blind person to watch the timely. image.

An example of the simulation software optimizing the first mirror 120 and the second mirror 130 will be described below with reference to FIG. Figure 3 shows the results of imaging quality. The horizontal axis in Fig. 3 is the period of the spatial frequency per millimeter, and the larger the value, the more precise the image. The vertical axis in Fig. 3 is the modulus of the optical transfer function (OTF), The larger the value, the better the image quality measured, and the modulus of the optical transfer function is generally 0.3 as an indicator for discriminating image quality. In addition, the x and y values of (x, y) in Fig. 3 represent the case where parallel light is concentrated at different angles.

As can be seen from FIG. 3, the modulus of the optical transfer function of the image display device of the present example can be greater than 0.4 at different positions. In other words, the image display device of the present example can have clear image quality under 30 line pairs per mm. In addition, this example enhances the analysis of large-angle rays (for example, the curve indicated by (-12.00, -8.50)) by slightly reducing the resolution of the center light (ie, the curve indicated by (0,0)). Degrees allow large angles of light as well as central light to maintain good resolution (all greater than 0.4).

Table 1 indicates the relevant parameters and imaging quality of this example, where relevant parameters include the exit pupil diameter, the effective focal length, the focal ratio, the eye relief, and the field pf view. The exit pupil diameter is the diameter D of the opening V in FIGS. 1 and 2. In this example, The exit pupil diameter is, for example, 8 mm. The eye distance is the shortest distance between the optical component and the human eye in the image display device, which is the shortest distance between the human eye and the first mirror. The field of view is the largest range visible to the human eye. In the present example, the field of view in the horizontal direction is, for example, 24 degrees (Table 1 is represented by 24° (H)), and the field of view in the vertical direction is, for example, 17 degrees (Table 1 is 17° (V) ))).

The modulation transfer function (MTF), distortion, and vignetting in Table 1 can be used as indicators for discriminating the image quality of the image display device. The modulation conversion function is the resolution of the image display device described in FIG. 3, and as illustrated in FIG. 3, the modulus of the optical transfer function of the present example may be greater than 0.4 per 30 pairs of lines. In other words, the image display device of this example has a good resolution. Further, in the aforementioned field of view (referring to 24° (H) ^* 17° (V)), the distortion amount of the pattern of the present example may be less than 1%, and the phenomenon of vignetting may be controlled within 10%. That is to say, the image display device of the present example can have good image quality.

In summary, the image display device of the present invention solves the problem of chromatic aberration by utilizing the characteristics of specular reflection, and can be applied to a system of visible light to infrared light, and allows an amblyopic patient and a blind person to view an image. In one embodiment, by combining the curved surface (free-form surface) with the mirror (including the first and second mirrors), in addition to eliminating other aberrations in the system, the number of lenses required by the system can be saved. The image display device has a relatively light weight and weight, thereby reducing the burden on the user when wearing.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art will not be able to The scope of protection of the present invention is defined by the scope of the appended claims.

100,200‧‧‧ image display device

110‧‧‧ display

120‧‧‧First mirror

130‧‧‧second mirror

140‧‧‧ frame

150‧‧‧Image capture device

L1, L2, L3‧‧‧ image light

U‧‧‧Monocular

V‧‧‧ openings

D‧‧‧diameter

S‧‧‧ inner surface

S1‧‧‧ first reflective surface

S2‧‧‧ second reflecting surface

Θ‧‧‧ angle

A120, A130‧‧‧ area

1 is a schematic diagram of an image display device according to an embodiment of the present invention.

2 is a schematic diagram of an image display device according to another embodiment of the present invention.

Figure 3 shows the results of imaging quality.

200‧‧‧Image display device

110‧‧‧ display

120‧‧‧First mirror

130‧‧‧second mirror

140‧‧‧ frame

150‧‧‧Image capture device

L1, L2, L3‧‧‧ image light

U‧‧‧Monocular

V‧‧‧ openings

D‧‧‧diameter

S‧‧‧ inner surface

S1‧‧‧ first reflective surface

S2‧‧‧ second reflecting surface

Θ‧‧‧ angle

A120, A130‧‧‧ area

Claims (9)

An image display device is disposed in front of a single eye of a user. The image display device includes: a display for outputting an image light; and a first mirror disposed on the transmission path of the image light, adapted to reflect the image And a second mirror located on the transmission path of the reflected image light and located outside the transmission path between the display and the first mirror, the two ends of the second mirror are respectively adjacent to each other The display and the first mirror, the first mirror reflects the image light to the second mirror, and the second mirror further transmits the reflected image light to the eye of the user, wherein the The ratio of the focal length of the first mirror to the focal length of the second mirror is between 1.4 and 2.4. The image display device of claim 1, wherein the image display device has a focal ratio of between 1 and 10. The image display device of claim 2, wherein the image display device has a focal ratio of between 3 and 10. The image display device of claim 1, wherein the first mirror and the second mirror are at an angle of between 35 degrees and 70 degrees. The image display device of claim 4, wherein the angle is 55 degrees. The image display device of claim 1, wherein the first mirror has a first reflecting surface, and the second mirror has a first The two reflecting surfaces, the first reflecting surface and the second reflecting surface are curved surfaces. The image display device of claim 1, wherein an area of the first mirror is substantially equal to an area of the second mirror. The image display device of claim 1, wherein the image light is visible light or infrared light. The image display device of claim 1, further comprising: an image capturing device electrically connected to the display, the image capturing device being adapted to capture an image and provide the image to the display So that the display outputs the image light.