JP2017097098A - Transmission type video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission type video display device capable of displaying a video excellent in visibility for a user, even when the brightness around the line-of-sight direction of the user is different from the brightness of other areas.SOLUTION: A transmission type video display device 1 includes a video display part 9 which displays the video, an optical part 12 which guides the video to the eye of the user, a light control filter 6 which makes the transmittance of external light variable and adjusts the light intensity of the external light reaching the eye of the user, a pupil imaging camera 7 which images the pupil of the eye of the user, and a control part 13 which calculates the pupil diameter of the pupil on the basis of an imaging signal from the pupil imaging camera 7 and adjusts each of the transmittance of the light control filter 6 and the light intensity of the video of the video display part 9 on the basis of the value of the calculated pupil diameter.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a transmissive image display device.

  In recent years, while being mounted on the user's head, the light of the image displayed on the image display unit and the light from the outside world are guided to the user's eyes, and the image is displayed on the image of the outside world. A transmissive image display device (a so-called transmissive head mounted display (transmissive HMD)) has been proposed (for example, Patent Document 1).

  In the transmissive image display device (glasses-type visual device) described in Patent Document 1, light is transmitted to the front side of a polarizing beam splitter that reflects the image to the user's eye side and transmits light from the outside. A dimming shutter (electrochromic element) having a variable rate is provided. When the user turns on / off the switch, the transmittance of the dimming shutter is lowered when the external environment is bright, and the transmittance of the dimming shutter is increased when the external environment is dark so that a clear image can be seen. To be able to.

  However, in the configuration in which the transmittance of the light-reducing shutter is adjusted according to the brightness of the external environment, if the light near the user's line-of-sight direction is different from the brightness of other regions, the light-reducing shutter is transmitted. The rate cannot be adjusted appropriately, and there is a possibility that an image with good visibility cannot be displayed to the user.

  Therefore, the present invention provides a transmissive video display capable of displaying a video with good visibility for the user even when the brightness in the vicinity of the user's line-of-sight direction is different from the brightness of other areas. An object is to provide an apparatus.

  In order to achieve the above object, a transmission-type image display device according to the present invention includes an image display unit that displays an image, optical means that guides the image to a user's eyes, and a transmittance of external light, A dimming filter that adjusts the light intensity of external light that reaches the user's eye, pupil imaging means that images the pupil of the user's eye, and the pupil diameter of the pupil based on an imaging signal from the pupil imaging means And a control unit that adjusts the transmittance of the dimming filter and the light intensity of the image on the image display unit based on the calculated pupil diameter value, respectively.

  According to the transmission type image display device of the present invention, the light of outside light is controlled by controlling the transmittance of the light control filter and the light intensity of the image of the image display unit based on the calculated value of the pupil diameter of the user. An image with good visibility can be displayed to the user not only when the intensity changes but also when the brightness near the user's line of sight changes.

1 is a perspective view showing an external appearance of a transmissive video display apparatus according to an embodiment. The side view which shows the state with which the user mounted | wore the transmissive | pervious image display apparatus. The top view which shows the state which the user mounted | worn with the transmissive | pervious image display apparatus. Schematic which shows the structure of a transmissive | pervious image display apparatus. The schematic sectional drawing which shows the structure of a light control filter. (A) is the figure which shows the state which has arrange | positioned the pupil imaging camera near the lower left end of the light guide plate for left eyes, (b) is the state which has arrange | positioned the pupil imaging camera near the upper right end of the light guide plate for right eyes FIG. The figure which shows the structure of a control part. The figure explaining the relationship between the light intensity of external light, the light intensity of transmitted light, and the light intensity of an image. The figure which showed an example of the relationship between the light intensity of an image | video, and the visibility level of an image | video when changing the transmittance | permeability of a light control filter. The figure which showed an example of the relationship between light intensity ratio and the visibility level of an image | video when changing the transmittance | permeability of a light control filter. The figure which showed an example of the relationship between a light intensity ratio and the visibility level of an image | video when a character image and a photographic image are displayed. The figure which showed an example of the relationship between the drive voltage of a light source, and the image illumination intensity in front when a whole surface white solid image is displayed. The figure which showed an example of the relationship between the pupil diameter of an eye, and external light illumination intensity. The figure which showed an example of the adjustment table previously memorize | stored in the memory | storage part of the main-control part. The figure which showed an example of the drive voltage of a light control filter, and the transmittance | permeability of a light control filter.

  Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a perspective view showing an external appearance of a transmissive video display apparatus according to the present embodiment, FIG. 2 is a side view showing a state in which a user (user) wears the transmissive video display apparatus, and FIG. FIG. 3 is a plan view showing a state in which the user wears the transmissive image display device. The transmissive video display device according to the present embodiment is a head-mounted display device (transmissive head mounted display) having a spectacle-shaped appearance.

  As shown in FIGS. 1 to 3, the transmissive image display device 1 includes a pair of device front surface portions 3 a connected to both sides of the connecting member 2 and a pair of temples connected to both sides of each device front surface portion 3 a. 3b, and by attaching the temple rear part 3b1 of the temple 3b to the side surface (near the ear) of the user's head H, the apparatus front surface part 3a is in front of the user's eyes. Located in the direction.

  The apparatus front surface portion 3 a includes a light guide plate 5, a light control filter 6 disposed on the front surface side (external light incident side), and a pupil imaging camera 7. Further, in the temple front part 3b2 of the temple 3b, as shown in FIG. 4, an image display unit 10, a light source 11, an optical unit 12, a control unit 13, a power source 14, and the like are provided. A half mirror 15 is provided at a position facing the eye LI of the light guide plate 5. FIG. 4 shows the configuration of the front part 3a and the temple 3b (the temple front part 3b2) on the left eye side of the transmissive image display apparatus 1, but the same is also configured on the right eye side.

  The transmissive image display apparatus 1 allows light (external image) incident from the outside through the dimming filter 6 to pass through the half mirror 15 to be visually recognized by the user and superimposed on the image from the image display unit 10. Can be displayed to the user. Hereinafter, each component of the transmissive video display apparatus 1 will be described.

  The video display unit 10 is configured by, for example, a liquid crystal display element, and a light source (for example, an LED backlight) 11 is disposed on the back side (the side opposite to the optical unit 12 side). By controlling the intensity of light emitted from the light source 11 with the control unit 13, the light intensity (luminance) of the image displayed on the image display unit 10 can be adjusted.

  The video to be displayed on the video display unit 10 can be supplied from the outside of the transmissive video display device 1 by wire or wireless, for example. Alternatively, a detachable storage unit (memory card or the like) may be provided in the transmissive image display device 1 and an image may be supplied via the storage unit.

  The optical unit 12 is a part that guides light (video) emitted from the video display unit 10 to the light guide plate 5, and includes, for example, a lens 16 and a mirror 17. The optical unit 12 may have a configuration including a plurality of lenses or a configuration using a prism or the like.

  The light guide plate 5 is a part that guides the light emitted from the optical unit 12 to the half mirror 15 while reflecting the light from the inner wall surface. The light guide plate 5 is formed of a resin having transparency to the wavelength of light emitted from the optical unit 12. The half mirror 15 is a part that reflects the light from the light guide plate 5 to the side opposite to the light control filter 6 (the user's eye side (left eye LI in FIG. 4)). The optical unit 12, the light guide plate 5, and the half mirror 15 are typical examples of optical means that guides the video displayed by the video display unit 10 to the eyes of the user.

  The light control filter 6 is a part that electrically changes the transmittance of light (external light) incident from the outside and adjusts the light intensity (luminance) of the external light reaching the user's eyes. The light control filter 6 is provided on the front surface of the light guide plate 5 (surface opposite to the user's eyes) so as to cover the user's field of view (field of view). The light control filter 6 can be comprised using an electrochromic element, for example. The electrochromic element can be formed, for example, on a glass substrate or a plastic substrate that is transparent to visible light.

  By using an electrochromic element as the dimming filter 6, the electrochromic element has a memory property with respect to the light shielding filter effect, and can maintain the light shielding property even when the power is turned off.

  Here, an example of the structure of the dimming filter 6 will be described with reference to FIG. The light control filter 6 can have a cell structure in which a titanium oxide particle film 21 and a display layer 22 are formed on a display substrate 20 and a counter substrate 24 is bonded through a spacer 23 of about 10 μm. In the cell structure, for example, 1-ethyl-3-methylimidazolium tetracyanoborate is enclosed as an electrolytic solution.

  The dimming filter 6 is configured so that the transmittance of the dimming filter 6 can be variably controlled by the control unit 13. This function can be realized, for example, by using a thin film transistor array having a high transmittance as the counter substrate 24 of the light control filter 6. For example, a user's view area (view area) is divided into a plurality of pixels, and a thin film transistor array including thin film transistors corresponding to each pixel is used as the counter substrate 24. The power supply to the display layer 22 of the dimming filter 6 is individually controlled by each thin film transistor, so that the transmittance of the display layer 22 can be variably controlled at an arbitrary position and size.

  Alternatively, if the specification allows rough control, for example, the counter substrate 24 of the dimming filter 6 is divided into several regions (segments) corresponding to the visual field region of the user, and individual wiring is provided for each segment. It may be provided. By controlling the power supply to the individual wiring, the transmittance of the display layer 22 can be variably controlled for each segment. This method is preferable in that an expensive component such as a thin film transistor array does not have to be used as the counter substrate 24.

  The dimming filter 6 may be configured to be detachable from the surface side of the light guide plate 5. Thereby, since it becomes easily exchangeable according to the consumption degree of the light control filter 6, it can always maintain in the state which is easy to see.

  The pupil imaging camera 7 is a camera for imaging the pupil of the user's eyes, and for example, an ultra-small CCD camera can be used. For example, as shown in FIGS. 3 and 6A, the pupil imaging camera 7 has a user's eye (pupil) near the lower end of the light guide plate 5 (in the drawing, near the lower left end of the left-eye light guide plate 5). ). Alternatively, as shown in FIG. 6B, the pupil imaging camera 7 is directed toward the user's eye (pupil) near the upper end of the light guide plate 5 (in the drawing, near the upper right end of the light guide plate 5 for the left eye). You may arrange. Note that the pupil imaging camera 7 is disposed on either one of the light guide plates (for example, the left eye light guide plate 5 as shown in FIG. 2).

  When the pupil imaging camera 7 captures the pupil of the user, the control unit 13 captures an imaging signal from the pupil imaging camera 7 and, for example, the diameter of the pupil imaged by a known image recognition process (hereinafter referred to as “pupil diameter”). Is calculated.

  As shown in FIG. 7, the control unit 13 includes a camera control unit 30, an image recognition unit 31, a pupil diameter calculation unit 32, a video display unit control unit 33, a light source voltage control unit 34, a dimming filter voltage control unit 35, and the like. The main control unit 36 for controlling the entire control unit is provided. The light source voltage control unit 34 adjusts the light intensity of the emitted light from the light source 11 by controlling the driving voltage of the light source (LED backlight) 11, and thereby the video luminance (video) of the video display unit 10. Light intensity) is controlled.

  The main control unit 36 of the control unit 13 can be configured to include, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a main memory, and the like.

  The power source 14 is a part that supplies power to the video display unit 10, the light source 11, the dimming filter 6, and the control unit 13. In the present embodiment, power is supplied from the single power supply 14 to the video display unit 10, the light source 11, the video display unit 10, the dimming filter 6, and the control unit 13. As the power source 14, for example, a secondary battery such as a lithium ion battery can be used. Note that the power source 14 may be provided outside the transmissive video display device 1 via a power cord.

  As shown in FIGS. 2 to 4, when the transmissive image display device 1 is mounted on the user's head, the image emitted from the image display unit 10 is an optical unit (lens 16, mirror 17) 12. The light is guided to the user's eyes through the light guide plate 5 and the half mirror 15, and external light (image) from the outside is incident on the user's eyes through the light control filter 6 and the half mirror 15. As described above, the transmissive image display device 1 can display an image superimposed on the external light (image) in the outside world for the user who wears the image. At this time, the dimming filter 6 appropriately blocks external light and makes it easy to view the image.

  The inventors of the present application derived the following formula (1) with respect to the transmittance (T) of the light control filter 6 of the transmissive image display device 1. Hereinafter, the derivation of Expression (1) and the technical significance will be mainly described.

T = (B × k) / (D × A) (1)
However,
B: light intensity of the image on the image display unit 10, k: image coefficient, A: light intensity of external light on the external light incident surface (front portion 3a) of the transmissive image display device 1,
D = −log ((Lmax−L0) / (Lmax−Lmin))

  Note that Lmax is the maximum value of the video viewability level, Lmin is the minimum value of the video viewability level, and L0 is the threshold value of the video viewability level.

  As shown in FIG. 8, the visibility of the image is adjusted by adjusting the intensity of the image light amount (image light intensity C) sent from the image display unit 10 and the amount of outside light (light intensity A of the outside light). It is determined by the amount of transmitted light (light intensity B of transmitted light) dimmed by the optical filter 6.

  The inventors of the present application use the transmission-type image display device 1 described above, and for a large number of subjects, character images and photographs while changing the transmittance of the dimming filter 6 in an ambient light environment with various brightnesses. Sensory evaluation of visibility was performed on the video in five stages. FIG. 9 shows an example of the sensory evaluation performed. FIG. 9 shows the visibility of character images when the transmittance of the dimming filter 6 is changed from 5% to 15% using the above-described transmission-type image display device 1 in an environment of 12000 lux of external light (easy to see. This is the result.

  As shown in FIG. 9, the higher the light intensity of the video, the higher the visibility level of the video, and the lower the light transmittance of the dimming filter 6, the higher the visibility level of the video. From this result, the present inventors considered that the ratio (C / B) between the light intensity B of the transmitted light and the light intensity C of the image described in FIG. 8 depends on the visibility of the image.

  Therefore, the light intensity ratio between the light intensity C of the image (image light intensity) and the light intensity B of the transmitted light B (the light intensity of the external light after passing through the light control filter 6) is defined as follows as the difference in the light amount. .

Light intensity ratio = light intensity of image / light intensity of transmitted light (light intensity of external light after passing through light control filter 6)
In addition, each light intensity was made into the measured value of an illuminance sensor, or a luminance sensor measured value. In addition, the light intensity of the image was the light intensity for a white solid image.

  FIG. 10 shows the result of plotting FIG. 9 as the degree of the level of the image with respect to the light intensity ratio. As shown in FIG. 10, the visibility level of the image at each transmittance (5%, 10%, 15%) of the light control filter 6 is all on the curve of the light intensity ratio and the visibility level of the image. The inventors of the present application have found that the level of visibility of an image is uniquely determined by the intensity ratio. Furthermore, although not shown, the brightness of the external light is in the range of 1000 lux to 50000 lux, and the brightness of any external light substantially matches the curve of the light intensity and the visibility level of the image in FIG. It has been found that the visibility is determined by the light intensity ratio defined by the inventors of the present application regardless of the brightness.

  In addition, as shown in FIG. 11, the visibility curve with respect to the light intensity ratio differs between an image having only two gradations such as a character image and a halftone image having multiple gradations such as a photographic image, It has been found that in order to increase the visibility (level of visibility of the video), it is necessary to increase the light intensity ratio of the halftone image. Based on these visibility sensory evaluation experiments, the inventors of the present application have derived that the visibility level (L) of an image is expressed as the following equation (2).

L = Lmax− (Lmax−Lmin) × exp (−k × S) (2)
However,
L: Video viewing level, Lmax: Video viewing level maximum value, Lmin: Video viewing level minimum value, k: Video coefficient, S: Light intensity ratio (= B / (A × T))

  In the light intensity ratio S (= B / (A × T)), B is the light intensity of the image of the image display unit 10, and A is the external light incident surface (front portion 3a) of the transmissive image display device 1. The light intensity of outside light at T, T is the transmittance of the light control filter 6.

  From formula (2), by selecting the threshold value (L0) of the video viewability level as the value of the video viewability level (L), the transmittance (T) of the light control filter 6 necessary for the video viewability Can be requested. That is the above equation (1).

  In the formula (2), the light intensity B of the image of the image display unit 10 means a detection value of the light intensity detecting means on the surface of the light guide plate 5 facing the eye. However, in this case, since the light intensity detection means interferes with the eyes, it is difficult to always provide the light intensity detection sensor on the surface of the light guide plate 5 facing the eyes.

  Therefore, as shown in FIG. 12, a light intensity detection sensor is attached to the surface of the light guide plate 5 facing the eye in advance when displaying the entire white solid image, and the driving voltage of the light source 11 of the image display unit 10 and the front of the eye The relationship between the light intensity of the image and the light intensity (image illuminance in FIG. 12) is measured, and the light intensity B value of the image of the image display unit 10 is calculated from the value of the driving voltage of the light source 11. The light intensity detection sensor is removed after this measurement.

  As a result, the light intensity detection means is not always provided on the surface of the light guide plate 5 facing the eyes, and the measurement result of FIG. Thus, the light intensity B of the image on the image display unit 10 can be calculated.

  In the expression (2), the video viewability level (L) can be set at multiple levels, and may be, for example, 5 levels or 10 levels. For example, in five stages, the maximum value of the video visibility level (L) is “5”, and the minimum value is “1”. Note that. The threshold value of the visibility level (L) of the video is preferably about 80% of the maximum value, and the threshold value is “4” in five levels.

  The video coefficient (k) in the equations (1) and (2) is a coefficient value determined by the video to be displayed, and is generally “15 to 50” for character video and “5 to 15” for halftone video such as photographs. Value.

  By the way, the scenery of the outside world is not uniform, for example, there are bright areas such as white walls and fluorescent light sources, and dark areas such as shadows and trees of buildings. Then, when the light intensity (A) of the external light on the external light incident surface (front portion 3a) of the transmissive image display device 1 is measured by, for example, a well-known illuminance sensor, the light from these scenes is used as an average value. taking measurement. For this reason, when the user's eyes are facing a white wall, for example, in the scenery, the intensity of the light coming from the white wall to the eyes is higher than the averaged light intensity measured by the illuminance sensor. Become stronger.

  Therefore, in the configuration in which the light intensity of the external light on the external light incident surface (front portion 3a) of the transmissive image display device 1 is measured with an illuminance sensor or the like, the visibility of the image may not be improved.

  As described above, in the configuration in which the light intensity of the external light on the external light incident surface (front portion 3a) of the transmissive image display device 1 is measured by the illuminance sensor or the like, where the user's line of sight is facing in the outside scene. There are times when it cannot respond to. Regardless of where the user's line of sight is directed, in order to ensure good visibility of the image, the transmittance of the dimming filter 6 (external light transmittance) according to the brightness of the region where the line of sight is directed. ) Need to be controlled.

  Accordingly, the inventors of the present application focused on the relationship between the pupil diameter of the eye and the intensity of external light (external light illuminance). FIG. 13 shows external light illuminance (light from outside light) based on data in the literature (“Effect of Illuminance on Visibility of Mobile Terminals” (Mobile Society Journal 2012 vol2 (2) pp81-85 FIG. 7)). (Intensity) and the pupil diameter.

  Based on the relationship between the external light illuminance (light intensity of external light) and the pupil diameter, the color of the eye (pupil), and the age shown in FIG. It was derived that (external light illuminance) A is expressed as the following formula (3).

A = exp (− (d−K1) / K2) (3)
However,
d: pupil diameter (mm), K1: coefficient determined by eye (pupil) color, K2: coefficient determined by age

  The coefficient K1 is a coefficient determined by the color of the eye (pupil), and is set to, for example, 0.4 to 0.5 for the brown system and 0.5 to 0.6 for the blue system. The coefficient K2 is a coefficient determined by age, and is set to about 5 to 6 in the 20s to 50s, and about 4 to 5 in the 60s or more, for example.

  In FIG. 13, black circle data shows the relationship between the external light illuminance (light intensity of external light) and the pupil diameter when the coefficient K1 is 5.5 and the coefficient K2 is 0.44.

  Thus, by calculating the pupil diameter of the user based on the imaging signal from the pupil imaging camera 7, the light intensity of the external light in the region where the user's line of sight is directed is expressed as illuminance from Equation (3). Can be calculated.

  The light intensity (external light illuminance) A at the eye of the external light calculated by the above formula (3) is used as A in the above formulas (1) and (2).

  When the transmission type image display apparatus 1 is mounted on the user's head, the pupil imaging camera 7 images the user's eyes (pupil) under the control of the camera control unit 30 of the control unit 13, thereby generating an image. The recognition unit 31 recognizes the pupil as an image based on the captured image signal, and the pupil diameter calculation unit 32 calculates the pupil diameter from the recognized pupil image.

  Then, the main control unit 36, based on the above equation (3), the light intensity (external light illuminance) A at the line of external light on the external light incident surface (front unit 3a) corresponding to the calculated pupil diameter. Is calculated. Further, the main control unit 36 compares the light intensity A at the line of sight of the external light and the light intensity B of the video emitted from the video display unit 10 under the control of the video display control unit 33 and the light source voltage control unit 34. The ratio (light intensity ratio S) is obtained, and an appropriate transmittance (T) of the dimming filter 6 is calculated based on the above formulas (1) and (2). Further, the main control unit 36 calculates the drive voltage of the dimming filter 6 so that the calculated appropriate transmittance (T) is obtained, and the drive voltage calculated from the power source 14 by the control of the dimming filter voltage control unit 35. It supplies to the light control filter 6.

  As described above, the pupil imaging camera 7 does not provide a light intensity detection means such as an illuminance sensor for detecting the light intensity (A) of the external light on the external light incident surface (front portion 3a) of the transmissive display device 1. Changes in the intensity (luminance) of external light near the line of sight of the user's eyes, regardless of where the user's eyes are looking, by imaging the user's eyes (pupil) and calculating the size of the pupil diameter Accordingly, the dimming filter 6 can be controlled to an appropriate transmittance so that the level of visibility of the displayed image can always be maintained satisfactorily.

  Furthermore, the light control filter 6 is controlled to an appropriate transmittance according to the change in the light intensity (luminance) near the line of sight that is being viewed, and the drive voltage of the light source 11 is also controlled accordingly to be displayed. The power consumption of the light source 11 can always be kept to the minimum necessary while maintaining the level at which the video is easy to see.

  Further, in the storage unit of the main control unit 36 of the control unit 13, the pupil diameter value calculated based on the imaging signal from the pupil imaging camera 7 calculated by the above formulas (1) to (3) is set. Correspondingly, an adjustment table in which the light intensity (luminance) value of the image of the image display unit 10 and the transmittance value of the dimming filter 6 are set in advance so that the image visibility level is equal to or higher than the threshold value is stored. It is good to keep.

  FIG. 14 is a diagram illustrating an example of an adjustment table stored in advance in the storage unit of the main control unit 36. In FIG. 14, the value of the drive voltage of the light source 11 corresponds to the value of the light intensity (luminance) of the image of the image display unit 10, and the value of the drive voltage of the dimming filter 6 is transmitted through the dimming filter 6. Corresponds to the rate value. In calculating the pupil diameter, in the above formulas (1) to (3), K1 (coefficient determined by the eye (pupil) color) is 5.5 and K2 (coefficient determined by age) is 0.44. , Lmax (maximum value of video viewing level) is 5, Lmin (minimum value of video viewing level) is 1, L0 (threshold level of video viewing level) is 4, and k (video coefficient) is 30. did.

  For example, the transmittance value of the dimming filter 6 in the adjustment table shown in FIG. 14 is the transmittance value calculated by the above equation (1), but about ± 20% of this value. If the transmittance value is within the error range, the level is practically acceptable. The adjustment table shown in FIG. 14 is an example, and an adjustment table corresponding to the user can be stored.

  The adjustment table as shown in FIG. 14 is stored in advance in the storage unit of the main control unit 36, so that the main table is based on the value of the pupil diameter calculated based on the imaging signal from the pupil imaging camera 7. The control unit 36 easily adjusts the transmittance of the dimming filter 6 and the light intensity (luminance) of the video on the video display unit 10 so that the level of visibility of the video is equal to or higher than the threshold by using the adjustment table shown in FIG. And it can adjust with high precision.

  Further, the main control unit 36 generates an adjustment table as shown in FIG. 14 based on the value of the pupil diameter calculated based on the imaging signal from the pupil imaging camera 7 based on the above formula (1) as needed. Based on the created adjustment table, the transmittance of the dimming filter 6 and the light intensity (luminance) of the video on the video display unit 10 are adjusted in multiple stages so that the level of visibility of the video is equal to or greater than the threshold. You may do it.

  As described above, based on the above formula (1), the adjustment table is created as needed according to the eye gaze direction of the user based on the value of the pupil diameter calculated based on the imaging signal from the pupil imaging camera 7. Thus, it is not necessary to store a plurality of adjustment tables in advance. Therefore, it is not necessary to increase the storage capacity of the storage unit, and the transmittance of the dimming filter 6 and the image display unit 10 are set so that the level of image visibility is equal to or greater than the threshold according to the user's line-of-sight direction. It is possible to quickly adjust the light intensity (luminance) of the video.

  Further, when calculating the pupil diameter of the user based on the imaging signal from the pupil imaging camera 7, by appropriately correcting according to the age of the user and the color of the eyes (pupil), the age of the user Regardless of race or the like, it is possible to maintain a good level of visibility of the displayed video.

  In the present embodiment, the power supply can be reduced in size and weight by supplying power from the single power supply 14 to the video display unit 10, the light source 11, the dimming filter 6, and the control unit 13. Can be reduced in weight.

  In addition, since the transmissive image display apparatus 1 of the present embodiment is a transmissive head mounted display having a spectacle-shaped appearance, it is possible to display an image with high visibility on the front of the eye.

<Preparation of light control filter>
In the transmissive image display devices of Examples 1 and 2 below, the electrochromic element used for the dimming filter was produced by the following method.

  ITO was formed on a 20 mm × 40 mm (thickness 0.3 mm) glass substrate by sputtering to form a conductive layer. A titanium oxide nanoparticle dispersion (SP210 manufactured by Showa Titanium Co., Ltd.) was applied to the upper surface of the conductive layer by a spin coating method, and annealed at 120 ° C. for 15 minutes to form a titanium oxide particle film. A 1 wt% 2,2,3,3-tetrafluoropropanol solution of a dye that produces a reduction color represented by the following structural formula (Chemical Formula 1) is applied to the titanium oxide particle film as a coating solution by a spin coating method at 120 ° C. A display layer having an electrochromic compound adsorbed on the surface of the titanium oxide particles was formed by annealing for 5 minutes.

  As the counter substrate, a glass substrate with ITO coated with a dye that oxidizes and develops a color by spin coating was prepared. The display substrate and the counter substrate were bonded to each other through a 10 μm spacer to manufacture a cell. Next, 1-ethyl-3-methylimidazolium tetracyanoborate as an electrolytic solution was injected into the cell to complete the electrochromic device. Thereafter, the entire periphery of the ends of the two glass substrates bonded together was sealed with a UV adhesive.

  For the produced electrochromic element (light control filter), for example, the relationship between the drive voltage and the transmittance as shown in FIG. 15 was obtained.

<Example 1>
The transmissive video display device 1 having the configuration shown in FIG. 1 was produced under the following conditions.
Display device body (device front surface portion 3a, temple 3b): mobile BT-200 (Epson)
Light control filter 6: electrochromic device (device fabricated by the above method)
Pupil imaging camera 7: CMOS camera module (Nippon Chemi-Con NCM03-V 8.4 × 11.8 × 5)
Display image: White text image (20-point text)

  Each pupil calculated based on the imaging signal from the pupil imaging camera 7 with K1 = 5.5, K2 = 0.44, Lmax = 5, Lmin = 1, L0 = 4, k = 30 in Equation (1) An adjustment table (for example, FIG. 14) of the transmittance of the dimming filter 6 composed of a matrix of the light intensity of the image with respect to the diameter (the value of the driving voltage of the image display unit 10) is created, and the main control unit illustrated in FIG. It memorize | stores in 36 memory | storage parts.

  Then, control was performed based on the created adjustment table, and when a character image was displayed outdoors at 10,000 lux, the dimming filter 6 was activated according to the light intensity of external light, and the characters were clearly visible.

<Example 2>
The transmissive video display device 1 having the configuration shown in FIG. 1 was produced under the following conditions.
Display device body (device front surface portion 3a, temple 3b): mobile BT-200 (Epson)
Light control filter 6: electrochromic device (device fabricated by the above method)
Pupil imaging camera 7: CMOS camera module (Nippon Chemi-Con NCM03-V 8.4 × 11.8 × 5)
Display image: White text image (20-point text)

  In equation (1), K1 = 5.5, K2 = 0.44, Lmax = 5, Lmin = 1, L0 = 4, k = 40, and the pupil diameter is calculated based on the imaging signal from the pupil imaging camera 7 Then, while controlling the value of the driving voltage of the light source 11 in the range of 1.5V to 2.5V, the dimming filter 6 (electrochromic filter) is controlled by the main control unit 36 and the light source voltage control unit 34 shown in FIG. The driving voltage of the device was controlled. In this control, programming was performed so as to refer to the data in FIGS. 12 and 14 as table data.

  Then, when a character image is displayed in a room of 1000 lux, in the shade of 10,000 lux, under a hot sun of 40,000 lux, the transmittance of the dimming filter 6 and the light intensity (luminance of the image) according to the light intensity of external light. ) Was automatically adjusted, and the character image was clearly visible even in the above-mentioned brightness environment.

DESCRIPTION OF SYMBOLS 1 Transmission type image display apparatus 5 Light guide plate 6 Light control filter 7 Pupil imaging camera 10 Video display part 11 Light source 12 Optical part 13 Control part 14 Power supply 36 Main control part

Japanese Patent No. 3371156

Claims (8)

A video display unit for displaying video;
Optical means for guiding the image to the user's eyes;
A dimming filter that varies the transmittance of external light and adjusts the light intensity of external light reaching the user's eyes;
Pupil imaging means for imaging the pupil of the user's eye;
The pupil diameter of the pupil is calculated based on the imaging signal from the pupil imaging means, and the transmittance of the dimming filter and the light intensity of the image on the video display unit are adjusted based on the calculated pupil diameter value, respectively. A transmission-type image display device. An adjustment table in which the transmittance value of the light control filter and the value of the light intensity of the image on the image display unit according to the value of the pupil diameter corresponding to the light intensity of outside light is stored in advance. ,
The control unit adjusts the transmittance of the light control filter and the light intensity of the image on the image display unit in multiple stages based on the calculated pupil diameter value and the adjustment table, respectively. 2. The transmissive image display device according to 1. The transmission type video display apparatus according to claim 2, wherein the transmittance (T) of the light control filter in the adjustment table is a transmittance value calculated by the following equation (1).
T = (B × k) / (D × A) (1)
Where B: light intensity of the image on the image display unit, k: image coefficient, A: light intensity at the line of external light on the external light incident surface of the transmissive display device,
In the above formula (1),
D = −log ((Lmax−L0) / (Lmax−Lmin))
However, Lmax: Maximum value of video viewing level, Lmin: Minimum value of video viewing level, L0: Video viewing level threshold A = exp (− (d−K1) / K2)
Where d: pupil diameter (mm), K1: coefficient determined by eye (pupil) color, K2: coefficient determined by age   The control unit creates the adjustment table according to the value of the pupil diameter calculated based on the imaging signal from the pupil imaging unit based on the formula (1), and based on the created adjustment table. 4. The transmission type image according to claim 3, wherein the transmittance of the light control filter and the light intensity of the image of the image display unit are respectively adjusted so that the level of visibility of the image is equal to or greater than a threshold value. Display device.   5. The power supply for supplying a drive voltage to the dimming filter and the power supply for supplying a drive voltage to the video display unit are configured by the same power supply. The transmissive image display device described.   The transmissive image display device according to claim 1, wherein the dimming filter is an electrochromic element.   The transmissive image display apparatus according to claim 1, wherein the light control filter is detachably provided.   The transmissive image display device is mounted on a user's head, and light from the outside is incident on the user's eyes through the light control filter and guided to the user's eyes via the optical means. The transmissive image display device according to any one of claims 1 to 7, wherein the transmissive image display device is a head-mounted display device that displays the image superimposed on an image of the outside world.