JP4691655B2 - Imaging display device - Google Patents

Description

  The present invention relates to an imaging display device that displays a captured image in a part of an observer's field of view and allows an external image to be observed in a see-through manner.

  2. Description of the Related Art Conventionally, there is an imaging display device that includes an imaging device and a display device. As an example of this imaging display device, there is a visual assistance imaging display device that captures a part of the field of view of the wearer wearing the display device on the head and displays the image to the wearer.

  This includes, for example, a night vision viewer using an infrared camera as an imaging device, a visual aid device for low vision using a high-sensitivity camera as an imaging device, and a vision for a narrow-sighted person using a wide-angle camera to expand the field of view. There are auxiliary devices (see Patent Documents 1 and 2).

  In addition, there is also known a combination of a visual aid imaging display device combined with a see-through display device that transmits external light and displaying a captured image superimposed on the wearer's normal field of view (Patent Literature). 1, 3, 4, 5).

When the above see-through display device is used, the display image is displayed so as to be superimposed on the normal field of view. Generally, when the external brightness increases, the display image becomes difficult to see. In addition, it is known to improve the visibility of a display image by changing the display position or performing external light shielding that reduces the amount of external light (see Patent Documents 6 and 7).
JP 2004-244745 A Japanese Patent No. 3000621 JP 2002-258208 A Japanese Patent Laid-Open No. 11-331731 JP 2002-23098 A Japanese Patent Laid-Open No. 2002-244077 JP-A-9-101477

  This is common in normal display images, but a part of the field of view as described above is captured and displayed on the normal field of view using a see-through display device to assist the wearer's field of view. In the imaging display device, it is preferable to use the normal field of view in a situation where the normal field of view can be secured. In addition, in an imaging device optimized for a low luminance region such as an infrared camera or a high sensitivity camera, when the luminance of the imaging region becomes high, it becomes out of the luminance corresponding region, and a captured image cannot be reproduced well due to a whiteout phenomenon or the like.

  An object of the present invention is to provide an imaging display device that secures a good field of view by giving priority to the normal field of view when a normal field of view is secured or when a captured image cannot be reproduced well.

  In order to achieve the above object, the present invention provides an imaging device that captures at least a part of a viewer's field of view, and displays an image captured from the imaging device in a part of the viewer's field of view, and an external image is seen through. An image display device that is observed in the above, wherein the luminance of at least a part of the image pickup area is greater than or less than the luminance that can be imaged by the image pickup device; The display brightness is lowered or the display image is turned off.

  According to the above configuration, the display brightness of the video display device is reduced or the display video is turned off when the normal visibility is ensured or when the captured video cannot be reproduced satisfactorily.

  Note that the luminance of the imaging area may be weighted by the area in the imaging area. For example, by using center-weighted metering, multi-segment metering, or the like, it is possible to provide an optimal display image that matches the use situation.

  The display luminance of the video display device can be controlled using an output signal of the imaging device or a display element drive signal of the video display device. According to this configuration, the luminance of the imaging area can be calculated without providing a photometric device to be described later, so if the situation where the normal field of view is secured or the captured video cannot be reproduced well, the display from the imaging device A favorable view can be secured by giving priority to the normal view over the video.

  Further, in place of the above-described luminance calculation method, a photometric device that measures the luminance of the imaging area of the imaging device and outputs it as a photometric signal is provided, and the display luminance control of the video display device is based on the photometric signal. Even so, a good field of view can be secured.

  In addition, it is desirable that the display luminance control of the video display device has a predetermined hysteresis. Specifically, control is performed by adding hysteresis to the reflection of temporal hysteresis and photometry signal, hysteresis by luminance area ratio, hysteresis to the rate of change of display luminance, and hysteresis based on time average of photometry signal. By doing so, a change in display luminance is suppressed with respect to a sudden change in photometric signal, and the observer can observe the display image comfortably.

  The hysteresis increases the display brightness again when the display brightness of the video display device is lowered or the display video is turned off, and after the display brightness of the video display device is lowered or after the display video is turned off. It may have different values depending on the case. Thereby, a change in display luminance is suppressed with respect to a sudden change in photometric signal, and the observer can observe the display image comfortably.

  In addition, the video display device includes a hologram as a combiner that guides the captured video and the external image simultaneously to the eyes of an observer. Thereby, a high see-through performance is obtained and a good field of view is ensured.

  According to the present invention, when the normal view is ensured or when the captured image cannot be reproduced satisfactorily, the normal view is given priority by reducing the display brightness of the image display device or turning off the display image. Visibility can be secured.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an imaging display device for visual assistance. The imaging display device 1 includes a head mounting portion 2 and a control box 4 connected to the head mounting portion 2 by a cable 3.

  The head mounting unit 2 includes a video display device 5, a photometric device 6 provided in the video display device 5, support means 7 that supports the video display device, and an imaging device 8 that is supported by the support means 7. The cable 3 is connected to the video display device 5 and the imaging device 8.

  The video display device 5 includes a video display element such as an LCD and an eyepiece optical system. And while making an observer observe an external field image see-through, the image | video imaged with the imaging device 8 is displayed, and it is provided to an observer as a virtual image. In the video display device 5 shown in FIG. 1, a portion corresponding to the right eye lens of the glasses is configured by bonding two transparent base materials 31 and 32 (see FIG. 2) described later. The detailed configuration of the video display device 5 will be described later.

  The photometric device 6 measures the luminance of the imaging area of the imaging device 8 and outputs it as a photometric signal to the control box 4. In FIG. 1, the photometric device 6 is provided in the video display device 5, but the installation location is not particularly limited. If the luminance of the imaging area of the imaging device 8 can be measured, the photometric device 6 is installed in any location of the head mounting unit 2. May be.

  The support means 7 supports the video display device 5 in front of the observer's eyes (for example, in front of the right eye), and includes a bridge 9, a frame 10, and a temple 11. In addition, although the frame 10 and the temple 11 are provided as a pair on the left and right, when they are distinguished on the left and right, they are expressed as a right frame 10R, a left frame 10L, a right temple 11R, and a left temple 11L. Further, the video display device 5 may be provided in the left eye and observed with both eyes. By observing the same image on the left and right, the visibility of the image is improved.

  One end of the video display device 5 is supported by the bridge 9. The bridge 9 supports a left-eye lens in addition to the video display device 5. The left-eye lens is also supported by the left frame 10L. The left frame 10L supports the left temple 11L so as to be rotatable. On the other hand, the other end of the video display device 5 is supported by the right frame 10R. An end of the right frame 10R opposite to the support side of the video display device 5 supports the right temple 11R so as to be rotatable. The cable 3 is a wiring for supplying an external signal (for example, a video signal, a control signal) and power to the video display device 5, the photometry device 6, and the imaging device 8, and is provided along the right frame 10R and the right temple 11R. ing.

  The imaging device 8 includes an imaging element such as a CCD or CMOS and an imaging optical system arranged in a housing, and images at least a part of the visual field of the observer. Therefore, the entire field of view of the observer, or the entire field of view of the observer and the peripheral area of the field of view may be captured. What is necessary is just to design this in the range suitable for the use of the imaging display apparatus. In FIG. 1, the imaging device 8 is provided on the right temple 11R. However, the installation location is not particularly limited, and may be provided at any location on the head mounting portion 2 as long as the visual field direction of the observer can be imaged. The head mounting unit 2 may be provided separately. For example, when a hand-held pen-type imaging device is used, the wearer's field of view, for example, the material at hand can be enlarged and observed in detail. Thus, depending on the application, it may be easier to operate than the head-mounted state.

  The control box 4 controls the video display device 5, the photometry device 6, and the imaging device 8 through the cable 3, and includes various operation units and a display unit in addition to a control unit and a power source.

  When the observer uses the imaging display device 1, the right temple 11R and the left temple 11L are brought into contact with the right and left heads of the observer, the bridge 9 is placed on the nose of the observer, and general glasses are worn. The head mounting part 2 is mounted on the observer's head so as to put it on. In this state, when the video image captured by the imaging device 8 is displayed on the video display device 5, the observer can observe the video image on the video display device 5 as a virtual image, and through this video display device 5, the outside world can be observed. The image can be observed see-through.

  Next, details of the above-described video display device 5 will be described. FIG. 2 is a cross-sectional view showing a schematic configuration of the video display device 5. The video display device 5 includes a video display element 20 and an eyepiece optical system 30.

  The video display element 20 includes a light source 21, a unidirectional diffuser plate 22, a condenser lens 23, and an LCD 24. The light source 21, the unidirectional diffusion plate 22, and the condenser lens 23 constitute an illumination optical system that illuminates the LCD 24.

  The light source 21 is composed of an RGB-integrated LED that emits light in three wavelength bands whose center wavelengths are, for example, 465 nm, 520 nm, and 635 nm. The light source 21 may be a white light source that emits white light.

  The unidirectional diffuser plate 22 diffuses illumination light from the light source 21, but the degree of diffusion differs depending on the direction. More specifically, the unidirectional diffuser 22 emits incident light of about 40 ° in a direction corresponding to the left-right direction when the head mounting unit 2 is mounted by the observer (a direction perpendicular to the paper surface of FIG. 2). The incident light is diffused by about 2 ° in the vertical direction (direction parallel to the paper surface of FIG. 2) when the observer wears the head mounting portion 2.

  The condensing lens 23 condenses the light diffused by the unidirectional diffusion plate 22. The condenser lens 23 is arranged so that the diffused light efficiently forms the optical pupil E. The LCD 24 is display means for displaying an image by modulating incident light based on the image signal.

  On the other hand, the eyepiece optical system 30 includes two transparent base materials 31 and 32 and an optical element 33. The eyepiece optical system 30 constitutes an optical device in which an external image is observed through through the joint surfaces of the transparent base materials 31 and 32, and enlarges and observes an image displayed on the image display element 20. This constitutes an optical device that guides the person's eyes as a virtual image. Thereby, the optical device constituting the eyepiece optical system 30 can be reduced in size and weight, and the video display device 5 can be reduced in size and weight. In addition, the eyepiece optical system 30 has a non-axisymmetric positive optical power, and the aberration of the image light incident on the inside is favorably corrected.

  The transparent base materials 31 and 32 are made of plastic (for example, acrylic resin or polycarbonate), and these are joined by an adhesive (not shown). The transparent base material 31 at this time is formed in a shape in which the lower end portion of the parallel plate is thinned toward the lower end to be wedge-shaped, and the upper end portion is thickened toward the upper end. The transparent base material 32 is configured so as to be integrated with the transparent base material 31 into a substantially parallel flat plate by forming the upper end portion of the parallel flat plate along the lower end portion of the transparent base material 31.

  For example, when the transparent base material 32 is not bonded to the transparent base material 31, the external world image is refracted when passing through the wedge-shaped lower end portion of the transparent base material 31. The image is distorted. However, the transparent base material 32 is joined to the transparent base material 31, and the substantially parallel flat plate is formed so that the surfaces of the transparent base materials 31 and 32 facing the eyes of the observer form the same surface. Thus, the refraction when the light of the external image is transmitted through the wedge-shaped lower end portion of the transparent base material 31 can be canceled by the transparent base material 32. As a result, it is possible to prevent distortion in the external image observed through the see-through.

  In addition, the transparent base materials 31 and 32 are good also as a correction spectacle lens which has a curvature. Also in this case, the transparent base materials 31 and 32 are integrally formed so that the surfaces facing the eyes of the observer form the same surface. The transparent base materials 31 and 32 may be configured using a plate-shaped half mirror and a lens, or may be a lens having a free-form surface subjected to a semi-transmission process.

  The optical element 33 is composed of a volume phase type reflection hologram that diffracts light in three wavelength bands, for example, 465 ± 10 nm, 520 ± 10 nm, and 635 ± 10 nm, which are incident at a specific incident angle. Reflective holograms have high external light transmittance and high transparency. The optical element 33 is affixed to the inclined surface at the lower end of the transparent substrate 31, and as a result, is sandwiched between the transparent substrates 31 and 32. The transmittance of the optical element 33 is set to 10% or more.

  Thus, since the optical element 33 is inclined with respect to the surface of the transparent base materials 31 and 32 facing the eyes of the observer, the optical degree of freedom is large, and the reflection at the optical element 33 is regular reflection. It can be a close angle. As a result, the observer can observe a highly efficient and optically corrected image.

  Here, the volume phase reflection hologram includes, for example, a process of attaching a photosensitive material such as a photopolymer on the transparent substrate 31, a process of exposing the photosensitive material with laser light, a fixing process by ultraviolet irradiation, and a baking process. It is formed through a bonding process by ultraviolet irradiation. The optical element 33 may be one in which an optical film having reflection / transmission characteristics is pasted on the transparent substrate 31 or a half mirror coat in which an inorganic material is coated on the bonding surface of the transparent substrate 31 by vapor deposition or the like. It may be.

  With such a configuration of the video display device 5, the light emitted from the light source 21 of the video display element 20 is diffused by the unidirectional diffusion plate 22, condensed by the condenser lens 23, and enters the LCD 24. The light incident on the LCD 24 is modulated based on the video signal and emitted as video light. At this time, the image itself is displayed on the LCD 24.

  The image light from the LCD 24 enters the inside of the transparent base 31 of the eyepiece optical system 30 from its upper end surface, is totally reflected a plurality of times by two opposing surfaces, and enters the optical element 33. The light incident on the optical element 33 is reflected and reaches the optical pupil E. At the position of the optical pupil E, the observer can observe an enlarged virtual image of the image displayed on the LCD 24. The distance from the optical pupil E to the virtual image is about several meters, and the size of the virtual image is 10 times or more that of the image displayed on the LCD 24.

  On the other hand, since the transparent base materials 31 and 32 and the optical element 33 transmit almost all light from the outside, the observer can observe the outside world image. Therefore, the virtual image of the image displayed on the LCD 24 is observed while overlapping a part of the external image. From the above, it can be said that the optical element 33 functions as a combiner that simultaneously guides the image provided from the image display element 20 and the external image to the eyes of the observer.

  As described above, the video display device 5 is configured to guide the video light emitted from the LCD 24 to the optical element 33 by total reflection in the transparent substrate 31. Accordingly, it is possible to provide a bright image to the observer by using the image light provided from the image display element 20 without waste. Further, the video display element 20 can be arranged at a position far away from immediately before the eyes of the observer, and a wide field of view of the observer with respect to the outside world can be secured. Moreover, the thickness of the transparent base materials 31 and 32 can be set to about 3 mm similarly to a normal spectacle lens, and the video display device 5 can be reduced in size and weight.

  In addition, since the optical element 33 diffracts only the light having the specific incident angle and the specific wavelength as described above, the optical element 33 does not affect the light of the external image transmitted through the transparent base materials 31 and 32 and the optical element 33. Therefore, the observer can observe the external image as usual through the transparent base materials 31 and 32 and the optical element 33. Further, since the transmittance of the optical element 33 is set to 10% or more, the observer can sufficiently observe the external field image through the transparent base materials 31 and 32 and the optical element 33.

  FIG. 3 is a block diagram illustrating a configuration of the imaging display device 1. Arrows indicate the signal flow. As described above, the head mounting unit 2 includes the video display device 5, the photometric device 6, and the imaging device 8. The control box 4 includes a power source 12 that drives the imaging display device 1, an operation unit 13 that is operated by an observer, a display unit 14 that displays an operation state and a driving state of the imaging display device 1, and the imaging display device 1. And a control unit 15 for controlling.

  The flow of each signal will be described. The video imaged by the imaging device 8 is output as a captured video signal and input to the control unit 15. The luminance information of the imaging area measured by the photometric device 6 is output as a photometric signal and is input to the control unit 15. The control unit 15 processes the captured video signal and outputs a display element driving signal to the video display device 5 and controls the display luminance of the video display device 5 based on the photometric signal.

  Next, the display brightness of the video display device 5 will be described. FIG. 4 is a diagram illustrating an image of the field of view of the wearer of the imaging display device 1. 40 is a field of view of the wearer, 41 is an imaging area of the imaging device 8, and 42 is a display image in which an observer visually recognizes an image captured by the imaging device 8. In FIG. 4, the imaging area 41 is designed around the center of the field of view 40, and the display image 42 is displayed superimposed on the center of the field of view 40.

  Here, when a high-sensitivity camera is used as the imaging device 8, it is possible to capture the imaging area 41 of the field of view 40 with low luminance and display a display image 42 brighter than the field of view 40. This imaging display device 1 can be used as a visual aid for visually impaired people. Further, when an infrared camera is used as the imaging device 8, it is possible to capture a dark imaging area 41 such as at night and display a display image 42 that cannot be seen in the field of view 40. This imaging display device 1 can be used as a night vision viewer. Thus, the imaging display device 1 can assist the situation of the field of view that is difficult for the wearer to see.

  By the way, the above-described visual field assistance is achieved under the situation where the imaging area 41 is within the range of luminance that can be imaged by the imaging device 8. When the imaging area 41 is outside the range of luminance that can be imaged by the imaging device 8, a good captured image cannot be obtained, and an appropriate display image 42 cannot be provided.

FIG. 5 is a diagram illustrating a luminance range that can be imaged by the imaging device 8. The horizontal axis represents the luminance input intensity to the imaging device 8, and the vertical axis represents the output intensity from the imaging device. The output intensity can be an output voltage or an output current corresponding to the luminance. When the input luminance is between the threshold values L ₁ and L ₂ , an output substantially proportional to the input luminance can be obtained, so that a good display image 42 as shown in FIG. 4 can be provided. On the other hand, if the input luminance is lower than the threshold value L _1, an output proportional to the luminance cannot be obtained due to the performance limit of the imaging device 8, and a dark image is displayed in normal control. On the other hand, if the input luminance is higher than the threshold L _2, an output proportional to the luminance cannot be obtained due to the performance limit of the imaging device 8, and an image that is too bright in normal control is displayed.

FIG. 6 is a diagram illustrating an image of the field of view of the wearer of the imaging display device 1 when a good display image 42 cannot be obtained. When the input luminance is lower than the threshold value L ₁ , the display image 42 is black, and in the area of the display image 42, it is not possible to see the outside image with see-through. On the other hand, when the input luminance is higher than the threshold value L ₂ , the display image 42 is white, that is, a so-called whiteout phenomenon, and the outside image cannot be observed in a see-through manner in the region of the display image 42. Therefore, the observer cannot visually recognize the vicinity of the center of the field of view 40 and cannot secure a good field of view. On the contrary, a better field of view can be obtained when the imaging display device 1 is not mounted.

Therefore, when a good display image 42 cannot be obtained, control is performed as follows. FIG. 7 is a flowchart showing the operation of the control unit 15. Control unit 15, the photometric device 6 receives a photometric signal in step S10, the measured luminance L in photometric signal proceeds to step S11, to determine lower or not than the threshold value L _1. If L <L ₁ in step S11, it is determined that a good field of view cannot be obtained, and the process proceeds to step S12 to reduce the display brightness of the video display device 5. The display brightness may be lowered to a level at which an external image can be observed in a see-through manner in the area of the display video 42. As a result, a field of view as shown in FIG. 8 is obtained, and the display image 42 is not black, but an external image is observed in a see-through manner in the area of the display image 42. In addition, as shown in FIG. 9, you may erase | eliminate the display image 42 completely, and according to this, a clearer external image is observed.

Meanwhile, if it is L ≧ L ₁ in step S11, the measured luminance L proceeds to step S13, it is determined whether or not higher than the threshold L _2. If it is L> L ₂ in step S13, it is determined that no satisfactory visibility is obtained, the complete display image 42 or lowering the display luminance of the image display device 5 in the same manner as step S12 proceeds to step S14 Turn off. At this time, it is considered that the field of view 40 is sufficiently bright and the normal field of view is secured. On the other hand, if L ≦ L ₂ in step S13, it is determined that a good field of view can be obtained, and the process proceeds to step S15 to output a display element drive signal having normal luminance to display the display image 42 in a superimposed manner.

  As described above, when the normal view is ensured or when the captured image cannot be reproduced satisfactorily, the normal view is prioritized over the display image 42 from the image pickup device 8, thereby ensuring a good view.

  Further, the display luminance can be controlled without using the photometric signal from the photometric device 8. In this case, it is not necessary to provide the photometric device 8, which leads to simplification, downsizing, and cost reduction of the device. FIG. 10 is a flowchart showing the operation of the control unit 15 when the photometric device 8 is not provided. When the control unit 15 receives the captured video signal from the imaging device 8 in step S20, the control unit 15 proceeds to step S21 and converts the captured video signal into a photometric signal in the control unit 15. Thus, the luminance information of the imaging area 41 can be obtained from the captured video signal. Then, the process proceeds from step S21 to step S11. Step S11 and subsequent steps are the same as the operation in FIG.

  As described above, since the luminance of the imaging area 41 can be calculated based on the captured video signal from the imaging apparatus without providing the photometric device 8, the situation where the normal field of view is secured and the captured video cannot be reproduced well. In this case, it is possible to ensure a good field of view by prioritizing the normal field of view over the display image 42 from the imaging device 8.

  Also, other means can control the display brightness without using the photometric signal from the photometric device 8. FIG. 11 is a flowchart showing another operation of the control unit 15 when the photometric device 8 is not provided. When the control unit 15 receives the captured video signal from the imaging device 8 in step S30, the process proceeds to step S31 and the captured video signal is converted into a display element drive signal in the control unit 15. Then, a photometric signal is calculated from the display element driving signal. Thus, the luminance information of the imaging area 41 can be obtained from the display element drive signal. Then, the process proceeds from step S31 to step S11. Step S11 and subsequent steps are the same as the operation in FIG.

  As described above, the luminance of the imaging area 41 can be calculated based on the display element drive signal without providing the photometric device 8, so that the situation where the normal field of view is secured and the captured image cannot be reproduced well, By prioritizing the normal view over the display image 42 from the imaging device 8, a good view can be secured.

  In addition, since the actual luminance of the imaging area 41 is not uniform depending on the location, weighting by area may be added to the photometry of the imaging area 41. For example, center-weighted metering or multi-segment metering can be used. FIG. 12 is a diagram for explaining center-weighted metering. An area near the center of the imaging area 41 is designated as a weighted metering area 43, and the weighted metering area 43 is metered with priority. That is, the control unit 15 controls the display luminance based mainly on the luminance measured in the priority photometric area 43. Usually, since the person who wants to see most is brought to the center of the field of view, by placing the weighted photometry area 43 near the center of the field of view 40, the part most desired to be viewed can be visually recognized well.

  FIG. 13 is a diagram for explaining multi-segment photometry. The imaging area 41 is divided into a plurality of cells 44, and the weighting is changed based on the luminance information of each cell 44. That is, photometry is performed with priority on a plurality of predetermined cells 44. That is, the control unit 15 controls the display luminance based mainly on the luminance measured by a plurality of predetermined cells 44. As a result, it is possible to provide an optimal display image 42 suitable for the use situation, such as ignoring the case where only a part of the luminance of the imaging area 41 is high, and reproducing the low luminance area with priority.

  Further, the actual luminance of the imaging area 41 is not uniform over time. For example, the brightness of the imaging area 41 changes when a moving high-luminance object such as a car light crosses the imaging area 41 or when the wearer of the head mounting unit 2 shakes his / her head to change the imaging area 41. . As described above, when there is an instantaneous luminance change such as when a high-luminance object crosses the imaging area 41, if the display luminance is changed in conjunction with it, the display luminance is greatly changed in a short time. Considering the physiological response of the human eye, it is not preferable that rapid brightness changes occur frequently.

FIG. 14 is a diagram illustrating an example of a change in luminance with respect to time. The horizontal axis represents time change, and the vertical axis is the input intensity of the brightness of the photometric signal, i.e. the imaging device 8, between the threshold L ₁ of L ₂ is in the range capable of imaging. Example A repeats a rapid change in luminance in a short time, and Example B changes the luminance in a long time.

  When the display brightness is controlled in conjunction with the change in Example A, the brightness changes abruptly and the observer becomes very tired. On the other hand, when the display brightness is controlled in conjunction with the change in Example B, the brightness changes gradually over a long period of time, so that the observer can comfortably observe the display image.

Therefore, in the case of Example A, it is effective to provide a temporal hysteresis for the control of display luminance and to provide a hysteresis for the reflection of the photometric signal. For example, between when the value of the photometric signal exceeds the threshold value L ₂ of the predetermined time T _2, the value of the photometric signal is measured or continues beyond a threshold L _2. If it continues to exceed, control is performed to reduce the display brightness or to turn off the display image. On the other hand, if it does not continue to exceed, normal brightness control is performed without reducing the display brightness or erasing the display image. In this way, by controlling the display brightness with temporal hysteresis, even when the value of the photometric signal changes rapidly in a short time as in Example A, the observer can comfortably observe the display image.

The predetermined time T ₂ may be stored in the imaging display device 1 in advance, or may be arbitrarily set by the user.

  In addition, when the photometry of the imaging area 41 is divided into a plurality of parts by multi-division photometry, an imaging video signal, a display element drive signal, or the like, the area outside the luminance range that can be imaged in the imaging area 41 has a predetermined ratio. When it exceeds, it may be controlled to reduce the display brightness or to turn off the display image.

FIG. 15 is a diagram illustrating an example of the area ratio outside the range of luminance that can be imaged with respect to time. The horizontal axis represents time change, the vertical axis represents the area ratio outside the range of imageable luminance in the imaging region, the threshold L ₃ which is the upper limit of the predetermined ratio. In Example C, after the ratio of the sum of the areas outside the luminance range that can be imaged slightly changes within the range of the threshold value L ₃ or less, the threshold value L ₃ is exceeded and the state continues.

Therefore, the display luminance control is provided with hysteresis due to the luminance area ratio. The divided value of the photometric signal of the image pickup area 41 to determine whether it exceeds the threshold value L _2, the area ratio of the imaging area 41 corresponding to photometric signal exceeding the threshold value L ₂ at the same time the threshold value L ₃ Determine if it has exceeded. And if it exceeds the threshold value L ₃ controls to turn off the or display video reducing the display brightness. On the other hand, if it does not continue to exceed, it is determined that there is not much influence on the field of view, and normal luminance control is performed without reducing the display luminance or erasing the display image. Thus, by controlling the display luminance with hysteresis based on the luminance area ratio, the observer can observe the display image comfortably.

In addition, the change rate of the photometric signal may be monitored, and the change rate of the display luminance may be a value within a predetermined range, with the change rate of the photometric signal having a predetermined magnification of 1 or less. FIG. 16 is a diagram illustrating an example of a change in photometric signal or a change in display luminance with respect to time. The horizontal axis represents time change, and the vertical axis represents photometric signal change or display brightness change. Example D shows a change in photometric signal, and Example E shows a change in display brightness. In Example D, and increases gradually the value of the photometric signal exceeds the threshold value L _2, then increases rapidly, then gradually increased to reach a predetermined value. In Example E, the display luminance gradually decreases, then decreases abruptly, and then gradually decreases to reach a certain value.

  FIG. 17 is a diagram showing the change rate of the photometric signal and the change rate of the display brightness in FIG. As can be seen, in Example E, the display luminance change rate decreases at a change rate with a magnification of 1 or less with respect to the luminance change rate obtained from the photometric signal, and becomes constant when it reaches a predetermined value. It rises at a rate of change with a magnification of 1 or less and reaches a certain value. Thus, by controlling the change rate of the display luminance with hysteresis, the change in display luminance is suppressed with respect to the abrupt change in photometric signal, and the observer can observe the display image comfortably.

Further, the display luminance may be controlled based on an average value of the photometric signal for a certain time. FIG. 18 is a diagram illustrating an example of a change in photometric signal or a change in display luminance with respect to time. The horizontal axis represents time change, and the vertical axis represents photometric signal change or display brightness change. Example F shows the change in the photometric signal, Example F ′ shows the average value of Example F over a certain time T _ave. , And Example G shows the change in display luminance.

In Example F, the value of the photometric signal suddenly rises from the threshold value L ₁ or less, reaches the peak after exceeding the threshold value L ₂ , then falls sharply and is constant at the threshold value L ₁ or less. In Example F ′, an average value at time T _{ave. Is} taken, so that a small peak is formed slightly later than Example F. The example G has a hysteresis based on the example F ′, increases as the example F ′ increases, reaches a certain value, and then decreases. In this way, by controlling the display luminance with hysteresis based on the time average of the photometric signal, a change in the display luminance is suppressed with respect to an abrupt change in the photometric signal, and the observer can observe the display image comfortably.

Further, the hysteresis may be different depending on whether the display brightness is lowered or the display image is turned off, and when the display brightness is raised. FIG. 19 is a diagram illustrating an example of a change in photometric signal or a change in display luminance with respect to time. The horizontal axis represents time change, and the vertical axis represents photometric signal change or display brightness change. Example H shows a change in photometric signal, and Example I shows a change in display brightness. In Example H, the value of the photometric signal rises and exceeds the threshold value L ₂ , gently reaches a peak, then falls and continues to a value equal to or lower than the threshold value L ₂ . In Example I, the display brightness decreases in conjunction with Example H exceeding the threshold value L ₂ , decreases to a constant brightness (including the display image being erased), and continues to have a constant value. _The display brightness has increased in conjunction with being less than ₂ . Here, the increase rate is slower than the display luminance decrease rate. Thereby, physiological dazzling due to a sudden increase in display luminance can be reduced.

  As described above, since the hysteresis at the time of lowering the display luminance is different from the hysteresis at the time of increasing, the change in the display luminance is suppressed with respect to a sudden change in the photometric signal, and the observer can observe the display image comfortably.

  A plurality of the above hysteresis can be used in combination. In this case, a better display image can be provided to the observer.

It is a perspective view of the imaging display device for visual assistance of the present invention. It is sectional drawing which shows the structure of the outline of the video display apparatus of this invention. It is a block diagram which shows the structure of the imaging display apparatus of this invention. It is a figure which shows the image of the visual field of the wearer of the imaging display apparatus of this invention. It is a figure which shows the luminance range which can be imaged of the imaging device of this invention. It is a figure which shows the image of the visual field of the wearer of the imaging display apparatus in case a favorable display image is not obtained. It is a flowchart which shows operation | movement of the control part of this invention. It is a figure which shows the other image of a wearer's visual field of the imaging display apparatus of this invention. It is a figure which shows the other image of a wearer's visual field of the imaging display apparatus of this invention. It is a flowchart which shows operation | movement of the control part when there is no photometry apparatus of this invention. It is a flowchart which shows other operation | movement of a control part when there is no photometry apparatus of this invention. It is a figure explaining the center weight photometry of this invention. It is a figure explaining the multi-segment photometry of this invention. It is a figure which shows the example of the luminance change with respect to time of this invention. It is a figure which shows the example of the area ratio out of the range of the brightness | luminance which can be imaged with respect to the time of this invention. It is a figure which shows the example of the change of the photometry signal with respect to time of this invention, or the change of display luminance. It is a figure which shows the change rate of the photometry signal of FIG. 16, and the change rate of display luminance. It is a figure which shows the example of the change of the photometry signal with respect to time of this invention, or the change of display luminance. It is a figure which shows the example of the change of the photometry signal with respect to time of this invention, or the change of display luminance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging display apparatus 5 Video display apparatus 6 Photometry apparatus 8 Imaging apparatus 40 Field of view 41 Imaging area 42 Display image

Claims (7)

An imaging device that captures at least a part of the viewer's field of view, and a video display device that displays a captured image from the imaging device on a part of the viewer's field of view and allows an outside world image to be viewed through An imaging display device,
When the luminance of at least a part of the imaging area is higher or lower and / or lower than the luminance that can be captured by the imaging device, the imaging display is characterized in that the display luminance of the video display device is reduced or the display video is turned off apparatus.   The imaging display apparatus according to claim 1, wherein the luminance of the imaging area is weighted by an area in the imaging area.   3. The imaging display device according to claim 1, wherein the display luminance of the video display device is controlled based on an output signal of the imaging device or a display element drive signal of the video display device.   3. The display device according to claim 1, further comprising: a photometric device that measures luminance of an imaging area of the imaging device and outputs the photometric signal as a photometric signal, and the display luminance control of the video display device is based on the photometric signal. Imaging display device.   The imaging display device according to claim 1, wherein the display brightness of the video display device has a predetermined hysteresis.   The hysteresis reduces the display brightness of the video display device or turns off the display video, and increases the display brightness again after reducing the display brightness of the video display device or after turning off the display video. The imaging display device according to claim 5, wherein the imaging display device has different values.   The image display apparatus according to claim 1, further comprising a hologram as a combiner that simultaneously guides the captured image and an external image to the eyes of an observer.

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