JP2011028011A - Video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optimum video display environment even in any eyesight state and audiovisual environment by including a lens function capable of variably changing a focus in front of a display and adaptively controlling the refractive index of the lens according to the eyesight state of a viewer and audiovisual distance to the display. <P>SOLUTION: A variable focus lens C13 is provided in front of the display C11 displaying video and a viewer recognition part C12 measuring the distance between the viewer and the display C11 is provided. A focus control part C14 controls the focal length of the variable focus lens C13 and display of the display C11 according to the eyesight state of the viewer and the audiovisual environment by previously storing the audiovisual distance when the viewer recognizes the optimum video and the focal length of the variable focus lens C13. The viewer can view clear video having high resolution as optimum video without the need of eyesight correcting means such as glasses and contact lenses as far as possible. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a video display device that displays video, characters, and the like mainly assuming that an individual views from a short distance to a medium distance.

  As an apparatus for displaying an image obtained by being captured or recorded by an imaging apparatus, there is an image display apparatus represented by a liquid crystal display. In recent years, image display devices have been improved in definition and resolution, and liquid crystal displays having more than 300 pixels per inch (300 dpi) have entered the stage of practical use. As the pixel density increases, it becomes possible to faithfully reproduce even finer information, and it will be possible to display information from a single newspaper in the future, even on small and medium-sized displays such as mobile phones and notebook PCs. It has become.

  However, there are individual differences in human visual abilities, and even with high definition and high resolution video display devices, it is often impossible to fully recognize fine characters and images, especially for myopia and hyperopia. Viewers who do not have sufficient visual acuity may not benefit. This situation will be described based on the visual principle outlined in FIG. That is, the light emitted from the subject is refracted by the cornea C21 and the crystalline lens C22 in the eye and imaged in the back of the eyeball. At this time, an image is accurately formed on the retina C23, so that the focus is achieved and the best visual ability is exhibited. The crystalline lens expands and contracts by surrounding muscles, and is adjusted to an optimum refractive index according to the distance from the subject.

  As shown in FIG. 2, the refractive index is increased when the distance to the subject is short, and the refractive index is decreased when the subject is far as shown in FIG. It is imaged and accurate information is delivered to the visual cells. With respect to the focus adjustable range by the expansion and contraction of the crystalline lens, referring to the current visual acuity test, a normal visual acuity state is obtained as long as it can handle a distance of 5 meters to several tens of centimeters.

  On the other hand, depending on the state of the crystalline lens adjustment function (myopia or hyperopia), it may not be possible to focus far or near, and the subject may appear blurred. FIG. 4 shows a state in which normal imaging cannot be performed because the refractive index of the crystalline lens is weak. This state is a so-called hyperopia state. The correction of visual acuity corrects these conditions by placing a lens that adjusts the overall refractive index (focal length) in combination with the refractive index of the crystalline lens in the eye or in front of the eye. This is done in order to obtain an appropriate visual acuity. As the correcting lens, a concave lens is used when the refractive index of the crystalline lens of the eye is higher than usual, and a convex lens is used when the refractive index of the crystalline lens of the eye is weaker than usual.

  As described above, no matter how high-resolution the video information is on the display, in order to accurately view such video information, it is necessary for the viewer to accurately adjust the focus according to the viewing distance. When such precise focus adjustment is difficult, correction means on the viewer side such as eyeglasses and contact lenses are required. Further, as means for adjusting the focal length, liquid crystal lenses represented by those described in Patent Document 1 have been proposed.

  The liquid crystal lens described in Patent Document 1 can be used as a variable focus lens by utilizing the property that the refractive index changes when a voltage is applied to the liquid crystal. In this liquid crystal lens, a first substrate having a transparent first electrode, a second electrode having a hole, and liquid crystal molecules accommodated between the electrodes so as to face the first electrode are arranged in one direction. The liquid crystal layer is provided, and the focus is variably controlled by controlling the alignment of the liquid crystal molecules by a voltage applied between both electrodes.

JP-A-6-46356

  Visual acuity correction using spectacles, contact lenses, etc. is a simple and effective correction means that has been used in the past. However, eye fatigue may be induced if correction is continued for a long time. Moreover, if the naked eye state and the correction state are properly used, time and labor are required each time a correction means such as glasses or contact lenses is attached or detached. Even if there is no problem in daily life, there are cases where correction is necessary only when viewing images on a television or mobile phone display or reading fine characters.

  In particular, elderly people tend to have difficulty in seeing nearby images because the muscles around the lens tend to decline with aging and hyperopia often progresses. For example, when using a device in which a display unit and an operation unit are integrated, such as a mobile phone or a notebook PC, there may be a situation where the distance that is easy to operate does not match the distance that is easy to view. In addition, if the viewer in myopic state also develops hyperopia, the range of focus adjustment becomes narrow and it becomes difficult to focus on both the hand and the video display device. Depending on the situation, troublesome measures such as replacing glasses with different focal lengths are required.

Therefore, by providing a lens function that can variably change the focal length (refractive index) on the front of the video display device, adaptive control of the focal length of the lens according to the visual acuity state of the viewer and the viewing distance to the video display device There is a problem to be solved.
An object of the present invention is to adaptively control the focal length of the lens function provided on the front surface of the video display device, so that the viewer does not need vision correction means (single-focus or multi-focus glasses / contact lenses). Another object of the present invention is to provide a video display device capable of viewing an optimal video, that is, a clear video with high resolution, according to the visual acuity state and viewing environment of the viewer.

  In order to solve the above problems, an image display device according to the present invention includes a display that displays an image, a variable focus lens that is disposed in front of the display and has an adjustable focal length, the display and a viewer. Viewer recognition means for measuring the distance, and focus control means for changing the focal length of the variable focus lens based on the distance measured by the viewer recognition means.

  According to this video display device, the viewer recognition unit measures the distance between the display and the viewer, and transmits the measurement result to the focus control unit. According to the visual acuity state of the viewer and the viewing distance to the display measured by the viewer recognition means, optimum focus correction is performed for the variable focus lens arranged on the display side, that is, the front surface of the display. As a result, it is possible to reproduce a clear image without requiring visual correction such as myopia and hyperopia as much as possible.

  In this video display device, the variable focus lens is composed of one or a plurality of optical lenses, and the position of the optical lens can be mechanically adjusted. In the case of an optical lens, it can be a varifocal lens that is out of focus when the focal length is changed. In addition, a lens using a material whose refractive index changes as the characteristics change may be used. Further, this variable focus lens can be a liquid crystal lens that electrically adjusts the refractive index by utilizing the change in the refractive index due to the applied voltage of the liquid crystal. In the case of a liquid crystal lens, the display and the lens can be formed integrally and realized at a lower cost than making them separately.

  Further, in this video display device, the viewer recognition unit includes a camera that captures the face of the viewer, recognizes the feature of the face from the captured image, and transmits the recognition result to the focus control unit. can do. When the focus control means changes the focal length of the variable focus lens, the viewer can identify the viewer by recognizing the features of the viewer's face, so the focal length of the variable focus lens is automatically adjusted so that an optimal image is obtained. Can be adjusted.

  Further, in this video display device, the focus control means may store the distance when the viewer is adjusted to the most visible state and the focal length of the variable focus lens with the video displayed on the display. it can. That is, the distance to the display that is the optimal image for the viewer and the focal length of the variable focus lens are stored as a combination. Such processing can be performed at the initial setting for starting display use, and can be set by a new viewer, or even by the same viewer, for example, after resetting glasses. it can.

  Further, in this video display device, the focus control means includes a distance stored as a value when adjusted to the most visible state and a variable focus lens as a focal distance corresponding to the distance measured by the viewer recognition means. It can be determined with reference to the combination with the focal length. That is, when the viewer displays an image on the display, the viewer recognition means measures the distance between the viewer and the display, and the information about the distance to the display and the focal length for the viewer is the optimal image. Can be used to determine the focal length of the variable focus lens corresponding to the measurement distance. That is, when the viewing distance changes, the optimum focus is adjusted at the new viewing distance accordingly.

  Further, in this video display device, the focus control means stores the distance to the display and the focal length of the variable focus lens when adjusted to a state in which the viewer can most easily recognize for each of a plurality of viewers. If the viewer changes, the focal length of the variable focus lens can be adjusted according to the viewer specified by using the facial features transmitted from the viewer recognition means. In other words, the distance to the display that is the optimal image and the focal length of the variable focus lens can be stored for each of a plurality of viewers, and can be distinguished for viewers that are distinguished using facial features from the viewer recognition means. Accordingly, the focal length of the variable focus lens can be adjusted.

  The display in this video display device can reduce the size of the video to be displayed in accordance with the refractive index adjustment of the variable focus lens. Moreover, this display can reduce the position of the image to be displayed and further adjust it in the vertical and horizontal directions when the refractive index of the variable focus lens is adjusted.

  The video display device according to the present invention has a visual acuity correcting means provided on the viewer side such as conventional glasses on the display side, that is, a variable focus lens as a visual acuity correcting means placed on the front of the display, The focal length of the variable focus lens is corrected according to the state and viewing distance. In the case of single-focus glasses / contact lenses, the viewer does not need such vision correction means, and in the case of expensive multi-focus glasses / contact lenses, single-vision vision correction means. In addition, it is possible to realize clear video playback with high resolution. When the variable focus lens is a liquid crystal lens, it can be manufactured integrally with the display panel, so it can be realized at a lower cost than making it separately.

It is a block diagram of video processing in the present invention. It is a figure explaining visual focus adjustment (state in focus at short distance). It is a figure explaining visual focus adjustment (state in which the focus was at a long distance). It is a figure explaining visual focus adjustment (state which is out of focus). It is a figure explaining the focus adjustment in this invention. It is explanatory drawing explaining the video reduction process of the display in this invention.

  An embodiment of a video display device according to the present invention will be described with reference to FIG. When using the display C11 which is an image display device according to the present invention, the display C11 is first placed at a distance that is normally used by the viewer, and a variable focus lens C13 whose focal length can be adjusted is disposed in front of the display C11. The The display C11 is provided with a viewer recognition unit C12 as viewer recognition means for measuring the distance between the display C11 and the viewer. The focus control unit C14 as a focus control unit receives information (signal) about the distance between the display C11 and the viewer measured by the viewer recognition unit C12, and based on the distance information, the variable focus lens Focus control for changing the focal length of C13 is performed.

  The variable focus lens C13 can be composed of one or a plurality of optical lenses (vari focus lenses). In this case, the composite focal length can be changed by mechanically adjusting the position of the optical lens. The varifocal lens C13 can also be constituted by a liquid crystal lens that controls the alignment of liquid crystal molecules with the voltage between the electrodes. In this case, the refractive index can be electrically adjusted. The variable focus lens C13 may be a lens made of a material that changes a refractive index with respect to an external electric input, for example.

  First, the focus control unit C14 performs an initial setting for focus adjustment of the variable focus lens C13 so that an image displayed on the display C11 can be normally viewed by the viewer. On the display C11, a Landolt ring used for visual acuity measurement or an image pattern similar thereto is displayed, and in the display state, the focal length of the variable focus lens C13 (under the control of the focus control unit C14 based on the operation of the viewer) (Refractive index) is adjusted to be optimum. The viewing distance between the display C11 and the viewer measured by the viewer recognizing unit C12 and the video that is most easily viewed by the viewer by focus adjustment according to the viewing distance, that is, the variable when the optimal video is obtained. The focal length of the focal lens C13 is stored as a combination. Thus, when viewing the display C11 in an individual fixed environment, viewing is performed while maintaining the adjustment state (adjustment with the remote controller) using the focus control unit C14 on the spot.

  Next, the display C11 is moved to a short distance or a long distance within a range in which the display C11 is normally used, and an optimum focus adjustment is performed according to the changed viewing distance, and the viewing distance measured by the measuring unit and the focus of the variable focus lens C13 are measured. Memorize the distance. In this way, for each viewer, a plurality of combinations of a plurality of viewing distances to the display C11 and a focal length of the variable focus lens C13 that is an optimal image at that time are stored.

  Although the user determination is basically performed by manual setting, the viewer recognition unit C12 has a camera function in addition to the viewing distance measurement, and can perform viewer face authentication. In order to perform viewer face authentication, the viewer recognition unit C12 captures the characteristics of the viewer's face in advance by using the camera function. When the viewer is changed, similarly, the viewing distance is changed and the viewing distance is measured, and each of the changed viewing distance and the focal distance at which the video can be optimally viewed by the viewer at the viewing distance. Are stored together with information about the viewer.

  The information measured as described above is stored on the display C11 side, and the initial setting is completed. Thereafter, the viewer recognition unit C12 performs face authentication of the viewer and measures the viewing distance between the display C11 and the viewer. The viewer recognition unit C12 recognizes the feature of the viewer's face based on the image information of the viewer's face photographed by the camera, authenticates the viewer's face based on the recognition of the feature point, and applies. If there is a viewer, the authentication result is transmitted to the focus control unit C14 together with the measured viewing distance. The focus control means C14 uses the focal length of the variable focus lens C13 based on the viewer identification information from the viewer recognition unit C12 using the face recognition information and the viewing distance information from the viewer recognition unit C12. (Refractive index) is adjusted.

  The focus control unit C14 corresponds to the viewing distance for the viewer according to the recognition result (specification of the face-authenticated viewer) received from the viewer recognition unit C12 and the measured viewing distance. The focal length of the variable focal length lens C13 is automatically adjusted so that the optimum focal length registered in advance is obtained. When the actual viewing distance is in the middle of the stored distance, a focal distance that can be regarded as optimum is calculated by linear interpolation from the measured distance before and after. By controlling the focal length of the variable focal length lens C13 in this way, the video displayed on the display C11 becomes the optimal video for the viewer. As a result, the viewer can view a clear optimum image through the variable focus lens C13 on the display C11 without requiring correction means such as glasses as much as possible (or without depending on expensive correction means). it can.

  As shown in FIG. 5, the case where the display C11 is viewed at a long distance is visually equivalent to the case where the display is viewed with the focus adjusted at a short distance. Since correction using glasses, contact lenses, etc. is basically a fixed refractive index, if the viewing distance changes significantly, the image may appear out of focus and the image may appear blurred. This can be mitigated.

  Since the image display apparatus according to the present invention corrects the focal length using the lens effect, if the focal length correction is increased in the direction in which the refractive index increases, the display size of the display C11 may appear different. is there. FIG. 6 shows this state. A video image in a state where the focal length is correct is shown in C61, and a video image in a state where the focal length is not correct is shown in C62. For example, when the refracting is performed using the variable focus lens C13 as a convex lens, the visible range is closer to the center of the display as indicated by C64, and the image at the edge of the screen becomes invisible.

  One solution to this is to reduce the display range of the display C11 in accordance with the focal length correction of the variable focus lens C13 and display the entire screen. C 63 is a reduced image displayed on the display C 11, but is recognized as an image equivalent to C 61 by being refracted by the variable focus lens C 13. As another solution, the display content of the display C11 can be changed by the display content or the operation of the viewer. In the case of video display that requires less viewing of the entire screen such as characters, the screen is not reduced, and the screen is scrolled, that is, adjusted in the vertical and horizontal directions when necessary. A state where the center of the screen is displayed is shown as C64, and a state where the lower right portion of the screen is displayed is shown as C65.

  The video display device according to the present invention assumes that a small and medium-sized display for personal use such as a mobile phone or a notebook PC is viewed at a short distance of several tens of centimeters to 1 meter or less. Needless to say, it can also be applied when viewing from a distance. Further, by finely changing the refractive index of the lens, it is possible to adjust the focus in accordance with the left and right visual acuity and the focus adjustment in accordance with the viewing position.

C11 ··· Display C12 · · Viewer recognition unit C13 · · Variable focus lens C14 · · Focus control unit C21 · · Cornea C22 · · Lens C23 · · Retina C61 · · Viewing state of the display (normal)
C62 ・ ・ Viewing state of the display (out of focus)
C63 .. Display reduction display processing C64 .. Normal display processing of display (after focus adjustment)
C65 .. Normal display processing of the display (after adjusting the focus, the image is adjusted to the lower right)

Claims (9)

A display for displaying images,
A variable focus lens disposed on the front of the display and adjustable in focal length;
Viewer recognition means for measuring the distance between the display and the viewer;
And a focus control unit configured to change the focal length of the variable focus lens based on the distance measured by the viewer recognition unit.   The video display device according to claim 1, wherein the variable focus lens is one or a plurality of optical lenses in which the focal length is adjusted by mechanically changing a position.   The video display device according to claim 1, wherein the variable focus lens is a liquid crystal lens in which the focal length is adjusted by electrically changing a refractive index.   The said viewer recognition means is equipped with the camera which image | photographs a viewer's face, recognizes the feature of the said face from the said picked-up image, and transmits the said recognition result to the said focus control means. Video display device.   In the initial setting, the focus control means stores the distance and the focal length of the variable focus lens when the viewer is adjusted to a state where the viewer can view the video most easily with an image displayed on the display. The video display device according to claim 1, comprising:   The focus control unit is configured to store the distance stored as a value when adjusted to the most visible state as the focal length corresponding to the distance measured by the viewer recognition unit and the variable focus lens. The video display device according to claim 5, wherein the video display device is determined with reference to a combination with a focal length.   The focus control means stores the distance and the focal length of the variable focus lens when adjusted to a state in which the viewer can most easily recognize for each of a plurality of viewers, and from the viewer recognition means The video display device according to claim 5, wherein the focal length of the variable focus lens is adjusted in accordance with a viewer who is distinguished using the transmitted facial features.   The image display device according to claim 1, wherein the display is configured to reduce a size of an image to be displayed in accordance with the adjustment of the focal length of the variable focus lens.   The video display device according to claim 8, wherein the display is further adjusted in the vertical and horizontal directions.

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