JP2011223238A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device containing an optical sensor which detects illuminance of ambient light on a display unit thereof and to which light from a nearby light source is applied by devising a guide lens for guiding the ambient light to the optical sensor.SOLUTION: One end face of a guide lens which is directed outward from an image display device is provided with sawtooth-like slope faces. Angles of the slope faces are different in accordance with height direction positions, so that light having incident angles in a predetermined range is guided to an optical sensor at each height direction position. Light from a distant light source is hard to be guided to the optical sensor at any height direction positions because the incident angle of the light is small.

Description

  The present invention relates to an image display device, and more particularly to an image display device with improved image quality adjustment according to the surrounding lighting environment.

  For image display devices such as plasma displays and liquid crystal displays, development of image quality adjustment methods for the illumination environment around the devices has been underway. When the illuminance from the surrounding illumination in the image display unit is high, for example, the brightness, contrast, sharpness, color density and color temperature are changed so that the user can see the image clearly. On the other hand, when the illuminance is low, the power consumption is reduced by, for example, lowering the luminance.

  Therefore, the image display device is provided with an optical sensor for detecting the illuminance of light from the periphery in the image display unit. From the viewpoint of design, since it is not preferable that the optical sensor is visible from the outside of the image display device, the optical sensor is provided inside the image display device. Therefore, a light guide lens for guiding ambient light to the optical sensor is required. One end surface of the light guide lens is attached to the outside of the image display device so as not to cause a problem in design.

Consider a situation where an image display device is actually placed in a living room. Since the illumination device is located at a high position in the room and light from a long distance illumination has a small incident angle to the light guide lens, it tends to easily reach the optical sensor through the light guide lens. Since the illuminance from the surrounding illumination in the image display section that is actually desired to be controlled is controlled by the illumination light at a short distance, there is often a difference between the illuminance detected by the optical sensor.
In order to cope with the above-described problem, Patent Document 1 discloses a technique that makes it easy for light from a short distance to reach an optical sensor by using a light guide lens as a biconcave lens.

JP 2010-11209 A

However, even in Patent Document 1, light from a distant illumination cannot be positively excluded. In order to correctly reflect the illuminance of ambient light in the image display unit in the image quality adjustment described above, in addition to increasing the sensitivity to light from a short distance illumination, to reduce the sensitivity to light from a long distance illumination Technology is desired.
In view of the above-described problems, an object of the present invention is to provide an image display device in which image quality adjustment according to the surrounding illumination environment is improved.

  In order to solve the above-described problems, the present invention provides an image display device having a built-in optical sensor for detecting the illuminance of ambient light in an image display unit, and a light guide lens for guiding the ambient light to the optical sensor. In the light guide, one end face is attached to the outside of the image display device, and the one end face has a sawtooth projection having a different inclination with respect to the height direction.

Further, in the image display device according to the aspect of the invention, the sawtooth-shaped protrusion may be configured such that the incident light with respect to the light guide has an incident angle within a predetermined range, and the incident light has an incident angle equal to or less than the predetermined angle. It is characterized in that it is formed so as to lead to the light sensor.
Further, according to the present invention, in the image display device, the sawtooth-shaped protrusion has an absolute value θ1 of an angle formed by the upper inclined surface with respect to the optical axis direction of the light guide, and the lower inclined surface is the guide. In the absolute value θ2 of the angle formed with respect to the optical axis direction of the optical body, θ2 is larger than θ1, and the sum of θ1 and θ2 is 90 degrees or less.

  ADVANTAGE OF THE INVENTION According to this invention, the image display apparatus which improved the image quality adjustment according to the surrounding illumination environment can be provided, and there exists an effect that it can contribute to the improvement of a user's viewing environment.

It is a figure which shows an example of the installation condition of an image display apparatus and illumination. It is a front view which shows an example of an image display apparatus. It is sectional drawing which shows an example of the conventional light guide lens. It is a figure which shows an example of the optical path in the conventional light guide lens. It is a figure which shows another example of the optical path in the conventional light guide lens. It is an external view of the light guide lens in one Example of this invention. It is sectional drawing of the light guide lens in one Example of this invention. It is the elements on larger scale of the light guide lens in one Example of this invention. It is the elements on larger scale of the light guide lens in one Example of this invention. It is a figure which shows the example of the optical path of the light guide lens in one Example of this invention. It is a figure which shows another example of the optical path of the light guide lens in one Example of this invention. It is a figure which shows the 1st example of the optical path of the light guide lens in one Example of this invention. It is a figure which shows the 2nd example of the optical path of the light guide lens in one Example of this invention. It is a figure which shows the 3rd example of the optical path of the light guide lens in one Example of this invention. It is a figure which shows the 4th example of the optical path of the light guide lens in one Example of this invention. It is the elements on larger scale of the detail of the light guide lens in one Example of this invention. It is a characteristic view of the distance from the light source and detected illuminance including an embodiment of the present invention. It is a figure which shows the measuring method of the characteristic view of FIG. 12A.

First, consider the situation where the image display device is placed in a living room.
FIG. 1 is a diagram illustrating an example of an installation state of an image display device and illumination. The image display device 1 is mounted on a stand 2 and is positioned at a height that is easy for the user to see. In FIG. 1, the image display device 1 is drawn from the left side surface, and the display unit is directed to the right side.

  Recent living rooms often have two lights, and FIG. 1 also shows two lights 3 and 4. One of them is illumination for the entire living room, and the other is illumination for a dining table (not shown), for example. Both the illumination 3 and the illumination 4 are located at a considerably higher position than the image display device 1, and are often directly attached to the ceiling, for example. The image display device 1 is irradiated with both the light beam 3 </ b> A from the illumination 3 and the light beam 4 </ b> A from the illumination 4.

  In FIG. 1, for example, the ceiling height of the living room is about 2.5 m and the width (horizontal direction in the figure) is about 5 m. In this case, the incident angle (perpendicular to the image display device, that is, the angle with respect to the horizontal direction in FIG. 1) of the light beam 4A from the illumination 4 far from the image display device 1 is, for example, 30 degrees or less. There are many cases. On the other hand, the incident angle of the light beam 3A from the illumination 3 with a short distance to the image display device 1 is about 40 to 45 degrees, and is often about 30 to 60 degrees, even if more estimated.

  FIG. 2 is a front view showing an example of the image display device 1, which is drawn from the right side of FIG. The image display device 1 includes a light guide lens 11, an infrared light receiving lens 12, and a display unit (display panel) 13. An infrared light receiving lens 12 for receiving infrared light including a control signal from a remote controller (not shown) is provided beside the display unit 13. For example, FIG. 2 shows an example in which the light guide lens 11 as the light guide described above is provided in the vicinity of the infrared light receiving lens 12.

  FIG. 3 is a cross-sectional view showing an example of a conventional light guide lens 11, and shows a case viewed from the left side of FIG. The light guide lens 11 is attached to a front frame (frame) 14 or a support member (not shown) with one end surface thereof facing the front outside of the image display device 1. One end surface on the opposite side of the light guide lens 11 faces, for example, the optical sensor 16 attached to the circuit board 15. The light from the illumination 3 and the illumination 4 guided into the image display device 1 by the light guide lens 11 is applied to the optical sensor 16. The optical sensor 16 detects the illuminance of the received light.

Next, the relationship between the incident angle of light with respect to the image display device 1 and the propagation of light inside the light guide lens 11 will be described.
FIG. 4 is a diagram illustrating an example of an optical path in a conventional light guide lens. For example, an example of a propagation path of a light beam having a large incident angle (for example, 60 degrees or more) like the light beam 3A from the illumination 3 in FIG. Is shown.

  The incident angle of the light beam 3A from the nearby illumination 3 with respect to the image display device 1 is large as shown in FIG. For this reason, the total reflected light on the surface of the light guide lens 11 as indicated by a broken line increases. Further, the light refracted and incident on the inside of the light guide lens 11 is repeatedly subjected to total reflection on the surface of the light guide lens 11 as shown in the figure until reaching the optical sensor 16. For this reason, more light leaks from the light guide lens 11 to the outside. For the above reasons, even when the light beam 3A from the nearby illumination 3 is irradiated to the light guide lens 11, the component that actually reaches the optical sensor 16 is often less than 10%, for example.

  On the other hand, FIG. 5 is a diagram showing another example of the optical path in the conventional light guide lens. For example, a light beam having a small incident angle (for example, 30 degrees or less) like the light beam 4A from the illumination 4 in FIG. An example of a propagation path is shown.

  The incident angle of the light beam 4A from the distant illumination 4 with respect to the image display device 1 is small as shown in FIG. For this reason, the total reflected light on the surface of the light guide lens 11 as shown by a broken line is small. Furthermore, the light refracted and incident on the inside of the light guide lens 11 is less frequently reflected by the surface of the light guide lens 11 before reaching the optical sensor 16. For this reason, there is little light leaking from the light guide lens 11 to the outside. For the above reasons, the light beam 4A from the distant illumination 4 is applied to the light guide lens 11 and then reaches the optical sensor 16 with high efficiency.

  For this reason, when the light guide lens 11 shown in FIG. 3 is used, the illuminance of the light that irradiates the image display device 1 is easily dominated by the near illumination 3, but the light detected by the optical sensor 16 There is a contradiction that the illuminance is easily controlled by the distant illumination 4.

An embodiment of the present invention is an embodiment for solving the above-described problem, and will be described with reference to the drawings.
FIG. 6 is an external view of a light guide lens 110 that is a light guide for guiding ambient light to an optical sensor in one embodiment of the present invention, and FIG. 7 is a light guide lens in one embodiment of the present invention. FIG. FIG. 7 shows a vertical sectional view through the center of the light guide lens in FIG.
That is, in this embodiment, one end face of the light guide lens 110 facing the outside of the image display device 1 has a slope having a sawtooth (triangle) cross section, and the slope angle of the slope is shown in FIG. It is changing with respect to the height direction.

Since the light guide lens 110 has this one end face, a light beam having a large incident angle of, for example, 30 degrees to 60 degrees with respect to the image display device 1 is efficiently guided to the optical sensor 16. It is possible to increase the sensitivity of the optical sensor 16 with respect to the light beam. On the other hand, for example, a light beam having a small incident angle of 30 degrees or less is totally reflected or refracted on the surface of the light guide lens 110 so as to make it difficult to reach the light sensor 16. Can be reduced.
By doing as described above, the illuminance of the light that irradiates the image display device 1 and the illuminance of the light detected by the optical sensor 16 have a corresponding relationship.

Next, the light guide lens 110 in this embodiment will be described in more detail.
FIG. 8 is a partially enlarged view of the light guide lens 110 according to an embodiment of the present invention, and shows the aforementioned sawtooth-shaped slope portion in the sectional view of FIG. With respect to the optical axis of the light guide lens indicated by the horizontal broken line in FIG. 8, the uppermost sawtooth-shaped protrusion has an angle of +14.8 degrees on the upper side and −25.91 degrees on the lower side. . In order, each protrusion is +11.6 degrees and -28.58 degrees, +6.8 degrees and -31.7 degrees, +3.7 degrees and -34.42 degrees, +3.7 degrees and -34.42 degrees, +6. It has angles of .8 degrees and -29.5 degrees, +11.6 degrees and -24.5 degrees, and +14.8 degrees and -20.2 degrees. That is, the sawtooth-shaped protrusions described above have a gentle slope on the upper surface and a steep slope on the lower surface compared to those on the upper and lower ends near the center. .

An optical path of light incident at each incident angle with respect to the light guide lens 110 illustrated in FIG. 8 will be described. In addition, the incident angle with respect to the light guide lens 110 refers to an angle with respect to a horizontal broken line (that is, an optical axis) in FIG.
FIG. 9A is a partially enlarged view of the light guide lens 110 according to an embodiment of the present invention, which is the same as FIG. 8, but among them, a relatively upper protrusion B describing the optical path and a protrusion C near the center. The reference numeral is selected. FIG. 9B is a diagram illustrating an example of the optical path of the light guide lens 110 according to an embodiment of the present invention, and illustrates the optical path at the protrusion B of FIG. 9A. FIG. 9C is a diagram illustrating another example of the optical path of the light guide lens 110 according to the embodiment of the present invention, and illustrates the optical path at the protrusion C in FIG. 9A.

  In FIG. 9B, since the upper slope of the protrusion B is relatively steep, for example, light incident at an incident angle of 40 degrees is less likely to be totally reflected by the upper slope. The light sensor 16 is totally reflected by the inclined surface and irradiated to the optical sensor 16. On the other hand, for example, even if light incident at an incident angle of 20 degrees or less is refracted to the inside, most of the light does not hit the lower slope and is not irradiated to the optical sensor 16. Although not shown, for example, light incident at an incident angle of 60 degrees or more is directed to the upper right in the figure even if it is refracted into the interior and totally reflected by the lower slope. 16 is not irradiated. That is, the protrusion B functions so as to selectively irradiate the light sensor 16 with light incident at an incident angle of 40 degrees, for example.

  In FIG. 9C, the upper slope of the protrusion C is relatively gentle. For example, light incident at a large incident angle of 60 degrees is hardly totally reflected by the upper slope, and most of the light is refracted inward. The light sensor 16 is totally reflected by the side slope and is irradiated to the optical sensor 16. On the other hand, for example, even if light incident at an incident angle of 20 degrees or less is refracted to the inside, most of the light does not hit the lower slope and is not irradiated to the optical sensor 16. Although not shown in the drawing, for example, light incident at an incident angle of 70 degrees or more is directed to the upper right direction in the figure even if it is refracted into the interior and totally reflected by the lower slope. 16 is not irradiated. That is, the protrusion C functions to selectively irradiate the light sensor 16 with light incident at an incident angle of 60 degrees, for example.

Next, the radial direction position of the light guide lens 110 and the incident angle of the light applied to the optical sensor 16 will be described.
10A to 10D are diagrams illustrating examples of the optical path of the light guide lens 110 according to an embodiment of the present invention, and light having incident angles of 60 degrees, 50 degrees, 40 degrees, and 30 degrees in order to the optical sensor 16. The optical path when irradiated is shown.

  That is, the light sensor 16 is irradiated with the component incident on the protrusion near the center of the light guide lens 110 for the light near the incident angle of 60 degrees. It can be seen that the light guide lens 110 functions so as to irradiate the optical sensor 16 with light having a small incident angle as it goes from the center to the periphery. That is, light from the light source 3 located at a relatively close position is incident on the light guide lens 110 at an incident angle of, for example, about 30 degrees to 60 degrees. The light sensor 16 is irradiated.

On the other hand, since the light from the light source 4 at a far position enters the light guide lens 110 at an incident angle of, for example, 30 degrees or less, the light sensor 16 is not irradiated by any protrusion of the light guide lens. Few.
For this reason, the illuminance detected by the optical sensor 16 is dominated by the light from the light source 4 located at a close position, and the illuminance of the ambient light on the display unit 13 of the image display device 1 can be reflected.

FIG. 11 is a partially enlarged view of the details of the light guide lens 110 in one embodiment of the present invention. With respect to the above-mentioned sawtooth-shaped projection, the angle θ1 of the upper slope and the angle θ2 of the lower slope with respect to the horizontal broken line (optical axis) in FIG.
An appropriate angle can be obtained in a range represented by θ1 <θ2 and θ1 + θ2 <90 degrees.

Next, measured characteristics are shown for the detected illuminance of light in the optical sensor 16 comparing the present example and the conventional example.
FIG. 12A is a characteristic diagram of the distance from the light source and the detected illuminance including one embodiment of the present invention, and FIG. 12B is a diagram showing a method for measuring the characteristic diagram of FIG. 12A.

As shown in FIG. 12B, the distance between the light source and the image display device (horizontal axis in FIG. 12A) measured by moving the image display device within a range of 0.5 m to 3.5 m from the light source, and the detected illuminance ( The characteristic between the vertical axis of FIG. 12A is shown in FIG. 12A.
That is, in the conventional example shown by the broken line, as described above, there is a problem that the detected illuminance is large with respect to light from a distant light source. On the other hand, in the present embodiment indicated by a solid line, the detected illuminance is increased with respect to light from a nearby light source, and it can be seen that the intended purpose has been achieved.

  The embodiments described so far are merely examples, and do not limit the present invention. For example, although eight sawtooth-shaped protrusions are shown in FIG. 6, any number may be used. Regarding the incident angle of the light applied to the optical sensor, the values shown so far are only examples, and other values may be used. The application target of the light guide lens 110 is not limited to an image display device such as a television, but may be another device, for example, an image display device that does not use an electronic display method. In addition, although different embodiments can be considered based on the spirit of the present invention, they are all within the scope of the present invention.

  1: Image display device, 3, 4: Illumination, 13: Display unit, 16: Optical sensor, 110: Light guide lens.

Claims (5)

An image display device having a built-in optical sensor for detecting the illuminance of ambient light in the image display unit, and a light guide for guiding the ambient light to the optical sensor,
The light guide is attached with one end surface facing the outside of the image display device,
The image display device, wherein the one end surface has a sawtooth-shaped protrusion having a different inclination with respect to a height direction.   2. The image display device according to claim 1, wherein the sawtooth-shaped protrusion is configured to cause the ambient light having an incident angle with respect to the light guide to be within a predetermined range, than the ambient light having an incident angle equal to or less than a predetermined angle. An image display device characterized in that the image display device is formed so as to be guided to the optical sensor.   2. The image display device according to claim 1, wherein the sawtooth-shaped protrusion has an absolute value θ <b> 1 of an angle formed by an upper inclined surface with respect to an optical axis direction of the light guide, and a lower inclined surface of the light guide lens. In the absolute value θ2 of the angle formed with respect to the optical axis direction, θ2 is larger than θ1, and the sum of θ1 and θ2 is 90 degrees or less.   3. The image display device according to claim 2, wherein the predetermined range of the incident angle is not less than 30 degrees and not more than 60 degrees.   3. The image display device according to claim 2, wherein the predetermined angle of incidence is within 30 degrees.

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