JPS63131667A - Display device - Google Patents

Abstract

PURPOSE:To display an image with high quality by forming the screen so that it is placed possible to be inclined from a vertical direction in a direction to face the outer plane of the screen downward to reduce adverse effect due to ambient light beams from the outside and re-reflected light beams in the inside of a screen. CONSTITUTION:A pivot supporting member 22 which supports pivotally the upper end part of the screen 21 and a tilt angle adjusting member 23 abutted with the lower part are provided, and by abutting the end part of an adjusting screw 24 formed adjustably freely with a projecting piece 23A from the outside of a main body 1, and giving a deviation force against abutting by a spring 25, the tilt angle theta of the screen 21 can be decided. Reflected light beams 31 from a reflecting mirror 8 are reflected on the back plane of the screen 21, and reflected light beams 32 are directed upward because the outer plane of the screen 21 is inclined by the angle theta downward, then a light quantity made incident on the reflecting mirror 8 is reduced. Also, the ambient light beams 11 are reflected on the outer plane of the transmission type screen 21, and are directed downward, thereby, the amount of reflected light beams 33 being inputted to the visual field of the eye 9 of an observer is reduced. In such way, it is possible to eliminate the adverse effect on the visual field of the observer, and to prevent the contrast of the image from being lowered.

Description

Detailed Description of the Invention [Field of Application in Industry A] The present invention relates to a display device that projects an image from the back side of a screen and displays the image on the outer surface of the screen, and particularly in the display image projected onto the screen. This is intended to reduce the influence of reflection of ambient light and to prevent a decrease in contrast due to image incident light re-entering the screen.

[Prior Art] In recent years, with the spread of high-definition video discs and old FiVTH, there has been an increasing demand for display devices that provide high-quality images on large screens. Projection televisions (so-called video projectors) are known as these display devices.

FIG. 5 shows a schematic configuration of a projection television as an example of a conventional rear projection display device of this kind.

In FIG. 5, reference numeral 1 denotes a display main body, and a screen 2 is disposed on the front surface of this main body 1 substantially perpendicular to the floor surface. Reference numeral 3 denotes a cathode ray tube disposed within the main body 1, and the displayed image is magnified by projection lens systems 4 and 5 and is incident on the back surface of the screen 2 via reflecting mirrors 6, 7 and 8.

Thereby, the viewer's eyes 9 see the image projected on the outer surface of the screen 2 from the front of the screen 2.

Here, one cathode ray tube 3 is sufficient for black and white images, but for color images, three cathode ray tubes corresponding to the three primary colors may be used. Collectively called.

[Problems to be Solved by the Invention] However, in the conventional rear projection display device described above, the screen 2 is disposed perpendicular to the floor surface or the bottom surface of the display body 1, so that the viewer cannot When the user is in a posture, the user is affected by undesirable reflected light from the outer and rear surfaces of the screen, resulting in a reduction in contrast and reflection of external light.

For example, as shown in FIG. 6A, ambient light 11 is reflected on the outer surface of the screen 2. Since this screen 2 is of a transmissive type, the reflectance is generally small, but a portion of the ambient light 11 is reflected at the reflection points 12 on the outer surface of the screen 2, and the reflected light 15 is transmitted to the viewer's eyes 9.
If the ambient light 11 that enters the field of view is from a light source 13 or a bright window 14, then for the observer, the screen 2
At the top, you will see an image reflected in the light source or the window, which will be a hindrance.

Here, when the light source 13 is close to the rear projection display device 1 or located at a high position (the angle of incidence of ambient light is large), the reflected light is reflected in the visual field of the observer's eyes 9. The effect of such reflection is small because it is difficult to enter the screen, but if the window 14 is located further away or lower than the screen (the angle of incidence of the ambient light is small), the ambient light reflected from the outer surface of the screen 2 The reflected light enters the field of view of the observer's eyes 9.

FIG. 6(B) shows how image light is reflected on the back surface of the screen 2. FIG. In FIG. 6(B), the image reflected light 16 from the reflecting mirror 8 is incident on the back surface of the screen 2. In FIG. Most of the incident light passes through the screen 2, but
A part of it is reflected by the back surface of the screen 2, and the reflected light 17 is further reflected by the reflecting mirror 8 and then enters the back surface of the screen 2 again. As a result, the contrast of the image on the screen 2 decreases, and the image quality deteriorates.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems and reduce the negative effects of ambient light from outside the screen and re-reflected light inside the screen on images projected on the screen, thereby achieving high quality images. An object of the present invention is to provide a display device capable of displaying images.

[Means for solving the problems] In order to achieve such an objective, in the present invention,
In a display device that projects an image from an image projection system to the back of the screen and displays the image on the outer surface of the screen, the screen is tilted from the vertical direction or made tiltable in a direction so that the outer surface of the screen faces downward. Features [Function 1] According to the present invention, the transmissive screen is tilted in such a direction that the outer surface of the screen faces downward, so that ambient light is reflected on the outer surface of the screen and has no effect on the observer's visual field. It is possible to reduce the adverse effects and the reduction in image contrast due to internally reflected light re-entering the back surface of the screen.

[Example 1] Hereinafter, the present invention will be described in detail and specifically based on an example shown in the drawings.

FIG. 1 schematically shows a projection television as an embodiment of the display device of the present invention.

In FIG. 1, reference numeral 21 denotes a transmission type screen, which is arranged around its upper end at an angle θ=2 to 15 degrees toward the inside of the main body 1 from the vertical direction.

22 is a pivot member that pivots the upper end of the screen 21. Reference numeral 23 denotes an inclination angle adjusting member that comes into contact with the lower end of the screen 21, and a projecting piece 238 provided on this member 23 has an end portion of an adjusting screw 24 that is adjustable from the outside of the main body 1 into the main body 1. bring it into contact. A biasing force is applied to the projecting piece 23A by a spring 25 to resist contact with the adjusting screw 24. With the above configuration, the inclination angle θ of the screen 21 can be appropriately determined as described below.

By tilting the screen 21, the screen 21
The defocusing of the above image can be resolved by readjusting the image projection system, for example by appropriately tilting the image plane of the cathode ray tube 3.

Therefore, in FIG. 1, the cathode ray tube 3 is
A means 27 for adjusting the position of the image is controlled to eliminate blurring of the image on the screen 21.

Since the remaining parts in FIG. 1 are the same as those in FIG. 5, their explanation will be omitted here.

The effects of internal reflection and external reflection on the inclined screen in this example are shown in Figures 2(A) and 2(A), respectively.
This will be explained with reference to B).

In FIG. 2(A), the reflected light 31 from the reflecting mirror 8 is reflected on the back surface of the screen 21, and the reflected light 32 is reflected in the direction shown in FIG. It is directed above the reflected light 17 by an angle 2θ. Therefore, the amount of reflected light 32 that enters the reflecting mirror 8 is smaller than the amount of reflected light 17 that enters the reflecting mirror 81 in the conventional examples shown in FIGS. 5 and 6(B). As a result, the amount of light that is re-reflected from the reflecting mirror 8 and enters the screen 21 is reduced compared to the prior art, thereby preventing a decrease in the contrast of the image on the screen 21.

FIG. 2B shows how ambient light is reflected on the outer surface of the screen 21. FIG. The outer surface of the screen 21 has an angle θ
Therefore, the ambient light 11 is reflected by the outer surface of the transmissive screen 21, and the reflected light 33 has a smaller angle 2θ than the reflected light 15 by the conventional screen 2 (Fig. i6 (A)). only pointing downwards. Therefore, the proportion of reflected light 33 entering the visual field of the observer's eye 9 is smaller than in the conventional example shown in FIGS. The impact of

Next, how to determine the inclination angle θ in the embodiment shown in FIG. 1 will be explained with reference to FIG. 3.

In FIG. 3, the vertical length of the screen 21 is 0.7+
11. The height from the installation surface of the device 1 to the lower end of the screen 21 is 0.5 m. Generally, in a display device such as a high-definition television commonly used in the present invention, an observer can
Since it is normal to view the screen from a distance approximately twice as far away, it is assumed that the position of the observer's eye 9 is 2.1 ml from the screen 21 in horizontal distance. In FIG. 3, 9A indicates the eye position when the observer is sitting on the floor, and 9B indicates the eye position when the observer is sitting on a chair, and the observer's eye 9 is considered to be between 9A and 9B.

Under these preconditions, the lighting source 13 and window 1 in the room
Ambient light 11 from 4 is incident on the screen 21, and the conditions under which the reflected light from the outer surface is visible to the viewer will be considered.

p! ! The height of the bright light source 13 is assumed to be 2.0 m. In general, it is more likely that the incident light from the light source 13 will be reflected off the outer surface of the screen 21 and enter the observer's eye 9 in the case of the eye 9A than in the case of the eye 9B, so the following will mainly discuss the eye 9A. .

Now, considering the case where the ambient light 11 from the light source 13 is reflected on the outer surface of the screen 21 and enters the eye 9A, as the inclination angle θ of the screen 21 increases, the screen 2
The reflection angle on the outer surface of 1 also increases by 2θ and becomes more downward. Therefore, when the reflected light at the upper end of the screen 21 becomes more downward and enters the eye 9A, in other words, when the reflection point on the outer surface of the screen 21 comes to the upper end of the screen as seen from the eye 9A, This is the most severe condition, and the angle θ at which the reflected light is incident on the eye 9A under this condition is determined as follows.

At this time, the angle of incidence θ of the reflected light from the screen 21 with respect to the eye 9A is determined by θ from tanθ2・0.5/2.1.
It is calculated as 2413.4 degrees.

On the other hand, if the room in which this display device is installed has an area of about 8 tatami mats, the horizontal distance X of the light source 13 from the screen 21 is about 3.0 m, so the light source 13
The angle θ1 of incidence on the outer surface of the screen 21 when θ=0 degrees is: From tanθ, = 0.8/3, θ, → 1
It will be 4.9 degrees. Therefore, since θ1>θ2,
When the eye 9 is between 9A and 9B, the light reflected by the illumination light source 13 in the room does not enter the observer's field of view.

That is, this light source 13 does not enter the field of view of the observer looking at the screen 21.

Next, when the illumination light source 13 is in a large room or in an adjacent room, x = about 5.0 m, and the incident angle θ1 at this time is θH9,1 from tanθ, -0,815.
degrees, so θ1<θ2. That is, the light source 13
This means that the ambient light 11 from the screen 21 is reflected by the outer surface of the screen 21 and enters the field of view of the eye 9A. Therefore, if θ2≦01+20, this ambient light 11 does not enter the visual field of the eye 9A.

therefore, becomes.

As can be seen from the above, in order to prevent the influence of reflection of the distant illumination light source 13 on the outer surface of the screen 21, it is necessary to tilt the screen 21 by θ=2 degrees or more. By the way) (=
If OO, tan θ, -0,810: Since θ1=0 degree from l-0, the inclination angle θ of the screen at this time is as follows.

That is, by tilting the screen 21 in the range of θ=2 to 7 degrees depending on the horizontal distance
It is possible to prevent the reflected light from the outer surface of eye 1 from affecting the eye 9A.

Next, consider the case of ambient light 11 from window 14. here,
For example, in an 8 tatami room, the distance from the screen 21 is 11
At a height of 3.0m, there is a window 1 above the height of 0.9m.
Suppose there is 4. At this time, consider a case where light from the lower end 14D of the window 14 is reflected at the upper end of the screen 21. At this time, since tan θI = (-0, 3)/3, θ = -5.7 degrees. Therefore, 1
If the screen 21 is tilted by 0 degrees or more, the ambient light from the window 14 will not enter the observer's eyes 9A after being reflected by the outer surface of the screen 21.

On the other hand, it has been confirmed through experiments that when the screen 21 is tilted with θ of 15 degrees or more, the image becomes unnatural when viewed by an observer.

As described above, according to the present invention, by tilting the screen 21 with θ between 2 and 15 degrees, the influence of reflected light on both the inner and outer surfaces of the screen 21 can be reduced.

However, the above-mentioned inclination angle θ is determined under certain conditions, and in most cases, setting θ in the range of 2 to 15 degrees eliminates the negative effects of internal and external reflected light. You can, but
Depending on the conditions of the place where the display device of the present invention is actually installed, adjust the screen adjustment screw 24 shown in FIG.
It is preferable to set the inclination angle θ of 1 to the optimum angle according to the installation conditions.

Incidentally, it goes without saying for those skilled in the art that the means for adjusting the inclination angle θ is not limited to the example shown in FIG. 1, and can be of various forms. For example, as shown in FIG.
It is also possible to appropriately adjust the inclination angle θ of the screen 21.

This inclination angle adjustment member 51 includes a ball joint portion 52 provided on the back of the bottom surface of the main body 1, an adjustment screw 53 attached to this ball joint portion 52, and
It has a screw receiver 54 installed on the installation surface 50 to support the. By rotating the adjusting screw 53 with its knob 53^, the screw 53 moves up and down the screw receiver 54 while being rotatable through the ball joint portion 52, thereby determining the inclination angle θ of the screen 21 at an appropriate angle. be able to. According to this example, there is an advantage that only slight processing is required on the outside of the existing display device, and the internal structure of the main body 1 can be left as is.

Furthermore, the interior of the main body 1, especially the parts that may be exposed to reflected light from the back of the screen 21, are finished in black to absorb such internally reflected light and prevent it from entering the screen 21 again. is suitable.

In order to tilt the screen 21 so that its outer surface faces downward, in the example of FIG. 1, the upper end of the screen 21 is pivoted and the lower end is freely adjustable. and the lower end can be pivoted, or alternatively,
Of course, both the upper end and the lower end can be adjusted to obtain a desired inclination.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the transmissive screen is tilted in such a direction that its outer surface faces downward, so that ambient light is reflected on the outer surface of the screen and It is possible to reduce the adverse effect on the observer's visual field and the reduction in image contrast due to internally reflected light re-entering the back surface of the screen.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIGS. 2(A) and 2(B) are explanatory diagrams of the state of reflected light on the inner and outer surfaces of the screen in this embodiment. 3 is an explanatory diagram of how to determine the inclination angle θ of the screen in the present invention, FIG. 4 is a configuration diagram showing the configuration of another embodiment of the present invention, FIG. 5 is a configuration diagram showing the configuration of a conventional example, FIGS. 6A and 6B are explanatory views of the state of reflected light on the outer surface and back surface of the screen of the conventional device, respectively. 1... Main body, 2.21... Transmissive screen, 3... Cathode ray tube, 4.5... Projection lens system, 6.7.8... Reflector, 9.9A, 9B. ...observer's eye, 13...light source, 14...window, 140...lower end of window, 22...pivot member, 23.51...inclination angle adjustment member, 23A... Projection piece, 24.53...Adjustment screw, 25...Spring, 26...Interlocking member, 27...Adjustment means, 50...Installation surface, 52...Ball joint part, 53A・...knob, 54...screw receiver. Fig. 1, Fig. 5, Fig. 5, 17, Anti-Physical Officer Fan, Shiba A, Fig. 6

Claims (1)

[Claims] 1) In a display device that projects an image from an image projection system onto the back side of a screen and displays the image on the outer surface of the screen, the screen is vertically moved in a direction in which the outer surface of the screen faces downward. A display device characterized by being tiltable. 2) The display device according to claim 1, wherein the screen is tiltable in a direction in which the outer surface of the screen faces downward by at least 2 to 15 degrees from the vertical direction. 3) The display device according to claim 1 or 2, wherein the direction of the image projection surface of the image projection system is adjustable according to the inclination of the screen. 4) In a display device that projects an image from an image projection system onto the back of a screen to display the image on the outer surface of the screen, the screen is tilted at least 2 to 15 degrees from the vertical direction in a direction in which the outer surface of the screen faces downward. A display device characterized by being tilted within a range of.