JPH11133509A - Fresnel lens sheet and back projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the shadow of a light shielding member such as a fastener arranged on the outside of a screen from being displayed on the screen. SOLUTION: The Fresnel lens sheet 2 is constituted of a transparent plate-like member formed to be rectangular in plane viewing, and the uncounted numbers of grooves 4 to realize the function of a Fresnel lens are concentrically formed on either surface of the sheet 2. A flat part 6 which is extended along the side part all over the area of each side part and whose front and back surfaces are smooth is formed on all the four side parts. Therefore, in the case of constituting the screen of the back projection display device of the sheet 2 and pressing the flat part 6 by the fastener so that the Fresnel lens is fixed on a screen frame, image light made incident on the side part of the Fresnel lens does not cause stray light because the grooves 4 are not formed at the flat part 6, whereby the shadow of the fastener is not formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fresnel lens sheet and a rear projection type display device using the Fresnel lens sheet.

[0002]

2. Description of the Related Art As a projection type display device for displaying an image by projecting image light on a screen,
2. Description of the Related Art A rear projection type display device that projects image light from the back of a screen is known. FIG. 3 is a configuration diagram showing an example of the rear projection type display device. In the display device 102 shown in the figure, first to third cathode ray tubes 104, 106, and 108 are accommodated in a lower portion of a casing 103, and the first to third cathode ray tubes 104, 106, and
The image light of three primary colors of red, green and blue emitted by 108 is transmitted through a first to third projection lenses 110, 112, 114 and a reflector 116 and a transmission type rectangular screen 118.
At the rear side. The first to third cathode ray tubes 104, 106, and 108 are arranged so that the image lights of the three primary colors are correctly combined on the screen 118. As a result, the screen 11
8, a color image can be seen from the front side of the screen 118.

FIG. 4 is a schematic perspective view showing a screen 118 constituting the display device 102 of FIG. 3 in an enlarged manner. As shown in FIG. 4, the screen 118 is configured such that the Fresnel lens sheet 120 and the lenticular lens sheet 122 are arranged close to each other, and the Fresnel lens sheet 120 is arranged inside the apparatus. The image light from the first to third projection lenses 110, 112, and 114 (FIG. 3) is incident on the Fresnel lens sheet 120 as light gradually diffused from the direction shown by the arrow A, and the screen surface Is converted into light that travels at substantially right angles. Then, the light enters the lenticular lens sheet 122 to form an image, and an image is formed on the lenticular lens sheet 122.

[0007] A number of black stripes 124 extending substantially vertically are formed on the light emitting surface side of the lenticular lens sheet 122.
4 improves the contrast by absorbing external light. In front of the lenticular lens sheet 122 (on the side opposite to the Fresnel lens sheet 120), the transparent panel 12 is positioned close to the lenticular lens sheet 122.
6 are disposed, and a lenticular lens sheet 12 is provided.
2 will be viewed through the transparent panel 126. Note that the transparent panel 126 may not be provided depending on the display device.

FIG. 5 is a partial cross-sectional side view showing the vicinity of the lower side of the screen 118 in detail. Transparent panel 126,
The lenticular lens sheet 122 and the Fresnel lens sheet 120 are arranged in this order inside the screen frame 128 in the order close to the screen frame 128, and the stopper 130 is brought into contact with the inner surface of the side of the Fresnel lens sheet 120, Fix the stopper 130 to the screen frame 1
It is attached to the screen frame 128 by being fixed to the screen frame 128 with screws 132. The Fresnel lens sheet 120 and the lenticular lens sheet 12
2, and a spacer (not shown) is interposed between the lenticular lens sheet 122 and the transparent panel 126, respectively. The stoppers 130 are arranged at, for example, a plurality of positions on each of the four sides of the Fresnel lens sheet 120 with an interval therebetween, and are screwed to the screen frame 128, respectively.

In general, this type of display device 102
In order to prevent an image from being chipped in a peripheral portion, a so-called overscan in which an image slightly larger than an effective screen is projected is performed. In FIG. 5, light L1
L4 is light incident on the peripheral portion of the Fresnel lens sheet 120 as a result of such overscan.
Even if the light that has entered the peripheral portion exits the Fresnel lens sheet 120, its principal rays L2 'and L3' are basically blocked by the screen frame 128 and do not exit outside the device. In the drawing, light L1 is light at the limit position, and light incident below the light L1 is blocked by the screen frame 128.

However, the light incident on the Fresnel lens sheet 120 is not all emitted in a desired direction because of a phenomenon peculiar to the Fresnel lens based on internal reflection. Direction, that is, a direction different from the direction of the chief ray. Light L shown in FIG.
Reference numerals 2 "and L3" indicate such stray light, which is reflected inside the Fresnel lens sheet 120 through a path as shown in the figure, and emitted upward largely away from the principal rays L2 'and L3' indicated by dotted lines. ing.

[0008] Although the lights L2 and L3 are incident on the lower side of the light L1, the stray lights L2 "and L3" are generated.
Are emitted outside the device without being blocked by the screen frame 128. Such stray light is weaker than the principal ray, and is observed only when the screen 118 is viewed obliquely (in FIG. 5, when viewed obliquely from above). No.

[0009]

However, as described above, the Fresnel lens sheet 120 has its sides fixed by the stoppers 130, so that the light L4 incident on the positions of the stoppers 130 is transmitted by the stoppers 130. Obstructed,
There is no stray light at that location. As a result, screen 1
When the display 18 is viewed obliquely, a shadow of the stopper 130 appears around the periphery of the screen 118, which is annoying.

Therefore, conventionally, the width of the screen frame 128 is increased as shown by a dotted line D in FIG.
3 "and the like are also blocked by the screen frame 128 to solve such a problem. However, as a result,
There has been a problem that the width of the screen frame 128 becomes unnecessarily large, which is not preferable in design, and that the effective screen area is reduced. The present invention has been made in order to solve such a problem, and an object thereof is to provide a Fresnel lens sheet in which a shadow of a light-blocking member such as a clasp arranged on a side portion of a screen is prevented from being displayed on the screen. And a rear projection display device.

[0011]

According to the present invention, there is provided a Fresnel lens sheet having at least one surface formed with an infinite number of grooves. It is characterized in that it has a flat portion that extends and has smooth front and rear surfaces. Further, the present invention provides a rear projection display device in which a screen is constituted by a Fresnel lens sheet, wherein the Fresnel lens sheet extends to the side along the side of the Fresnel lens sheet, and the front and back surfaces are smooth. It is characterized by having a flat part.

In the Fresnel lens sheet of the present invention, since a flat portion is formed at the side portion, stray light due to internal reflection peculiar to the Fresnel lens is not generated at this portion. In the rear projection display apparatus of the present invention, as long as the flat portion is hidden by the screen frame, even if a fixture or the like is arranged on the flat portion, the shadow of the fixing device or the like is not displayed on the screen.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1A is a plan view showing an example of the Fresnel lens sheet according to the present invention, FIG. 1B is a side view when viewed from the left side in the figure, and FIG. 1C is a view when viewed from below in the figure. It is a side view. The Fresnel lens sheet 2 is made of a transparent plate-like member formed in a rectangular shape in a plan view, and has an infinite number of concentric grooves 4 on one surface for realizing the function of the Fresnel lens. Further, a flat portion 6 having a smooth front and rear surface is formed on all four sides and extends along the entire side of each side. Such a Fresnel lens sheet 2 is specifically,
It can be formed using an ultraviolet curable resin, or can be formed by a technique of press molding or casting.

FIG. 2 is a partial sectional side view showing a main part of a rear projection type display device in which a screen is formed by the Fresnel lens sheet 2 shown in FIG. 1, and is a drawing corresponding to FIG. In the figure, the same elements as those in FIG. 5 are denoted by the same reference numerals. The basic configuration of the rear projection type display device 8 is the same as that of the rear projection type display device shown in FIG. 3 except that the screen 3 is formed by the Fresnel lens sheet 2, and thus the description thereof is omitted here.

The transparent panel 126, the lenticular lens sheet 122, and the Fresnel lens sheet 2 are arranged in this order inside the screen frame 128 in the order close to the screen frame 128 in the same manner as in the prior art. The stopper 130 (fixing device according to the present invention) is brought into contact with the inner surface of the portion, and the stopper 130 is fastened and fixed to the screen frame 128 with the screw 132 to be attached to the screen frame 128. The Fresnel lens sheet 2, the lenticular lens sheet 122, and the lenticular lens sheet 122
A spacer (not shown) is interposed between the transparent panel 126 and the transparent panel 126. The stoppers 130 are disposed, for example, at a plurality of positions on each of the four sides of the Fresnel lens sheet 2 with a space therebetween, and the screen frame 12
It is screwed to 8.

In the rear projection display device 8, first, the light L incident on the lower side 10 of the Fresnel lens sheet 2 obliquely from above at a location other than the stopper 130.
5, after entering into the Fresnel lens sheet 2 as shown in FIG. 2, the light is reflected on the inner surface of the flat portion 6 to face obliquely downward, and is repeatedly reflected in the lower side portion 10. Therefore,
It does not become stray light and exit from the Fresnel lens sheet 2 to the lenticular lens sheet 122 side as in the related art. On the other hand, the light L7
Is blocked by the stopper 130 and does not enter the Fresnel lens sheet 2, so that the light L 7 does not exit to the lenticular lens sheet 122 side.

That is, in the rear projection display device 8, neither the light incident on the lower side portion 10 at a location other than the fastener 130 or the light incident on the location of the fastener 130 does not exit to the lenticular lens sheet 122 side. Therefore, the shadow of the fastener 130 is not displayed on the screen 118. Therefore, in the rear projection type display device 8 using the Fresnel lens sheet 2, it is not necessary to particularly widen the screen frame 128, and it is possible to improve the device design and increase the effective screen area.

As described above, the present invention has been described based on the embodiment. However, this is merely an example, and the present invention can be implemented in various forms without being limited to this example. For example, in the present embodiment, the flat portion 6 is formed on all four sides, but the screen 1
In the case where the user rarely looks at the image while looking up from below, it is considered that the shadow generated on the upper side is not particularly problematic. Side (for example, top side)
It is also possible to eliminate the need for forming the flat part 6 in FIG.
Further, the stray light generated at the left side and the right side travels obliquely to the left and right. Such a stray light is blocked to some extent by the black stripe 124 formed on the lenticular lens sheet 122, so that a black stripe is formed. When the screen is configured in combination with the lenticular lens sheet, a configuration in which the flat portion 6 is not formed on the left side and the right side is also effective.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Good results can be obtained by selecting the dimensions of the Fresnel lens sheet 2 as follows, for example. That is, when the screen size is 41 inches, the overall dimensions of the Fresnel lens sheet 2 are 871 mm in width and 6 in length.
63 mm. Then, a rectangular area 12 having a width of 839 mm and a height of 631 mm at the center of the Fresnel lens sheet 2.
FIG. 1 shows a groove 4 for realizing the function of the Fresnel lens.
Is formed, and a flat portion 6 having a width of 16 mm is formed on four outer sides thereof. On the other hand, the inner edge of the screen frame 128 is
The width is 833 mm and the length is 625 mm.

[0020]

As described above, according to the present invention, there is provided a Fresnel lens sheet having an infinite number of grooves formed on at least one surface thereof, wherein the surface extends along the side of the Fresnel lens sheet. And a flat portion having a smooth back surface. Further, the present invention provides a rear projection display device in which a screen is constituted by a Fresnel lens sheet, wherein the Fresnel lens sheet extends to the side along the side of the Fresnel lens sheet, and the front and back surfaces are smooth. It is characterized by having a flat part.

That is, in the Fresnel lens sheet of the present invention, since a flat portion is formed on the side portion, stray light due to internal reflection peculiar to the Fresnel lens does not occur at this portion. In the rear-projection display device of the present invention using the above, as long as the flat portion is hidden by the screen frame, even if a fixture or the like is arranged on the flat portion, the shadow thereof will not be displayed on the screen. Therefore, it is not necessary to particularly widen the screen frame, and it is possible to improve the device design and increase the effective screen area.

[Brief description of the drawings]

FIG. 1A is a plan view showing an example of a Fresnel lens sheet according to the present invention, FIG. 1B is a side view when viewed from the left side in the figure, and FIG. FIG.

FIG. 2 is a partial cross-sectional side view showing a main part of a rear projection display device in which a screen is formed by a Fresnel lens sheet.

FIG. 3 is a configuration diagram illustrating an example of a rear projection type display device.

FIG. 4 is an enlarged schematic perspective view showing a screen constituting the display device of FIG. 3;

FIG. 5 is a partial cross-sectional side view showing the vicinity of the lower side of the screen in detail.

[Explanation of symbols]

2 ... Fresnel lens sheet, 3 ... Screen, 4 ...
... Groove, 6... Flat portion, 8... Rear projection display device, 102... Display device, 104. 110, a first projection lens, 112, a second projection lens, 114, a third projection lens, 116
… Reflector, 122 lenticular lens sheet, 124 black stripe, 126 transparent panel, 128 screen frame, 130 fastener,
132 ... screws.

Claims (9)

[Claims] 1. A Fresnel lens sheet having an infinite number of grooves formed on at least one surface thereof, comprising a flat portion having a smooth front and rear surface extending along the side of the Fresnel lens sheet. Further, a Fresnel lens sheet characterized in that: 2. The Fresnel lens sheet is formed in a substantially rectangular shape in a plan view, and the flat portion is formed on one or more or all of an upper side, a lower side, a left side, and a right side. 2. The Fresnel lens sheet according to claim 1, wherein the Fresnel lens sheet extends over substantially the entire area. 3. The Fresnel lens sheet according to claim 1, wherein the Fresnel lens sheet is formed in a substantially rectangular shape in a plan view, and the flat portion extends over substantially the entire lower side portion. 4. A rear projection display device in which a screen is constituted by a Fresnel lens sheet, wherein the Fresnel lens sheet extends to the side along the side of the Fresnel lens sheet, and the front and back surfaces are smooth and flat. A rear projection type display device, comprising: 5. The Fresnel lens sheet is formed in a substantially rectangular shape in a plan view, and the flat portion has one or more or all of an upper side, a lower side, a left side, and a right side. 5. The rear projection display device according to claim 4, wherein the rear projection display device extends over substantially the entire area. 6. The rear projection display device according to claim 4, wherein the Fresnel lens sheet is formed in a substantially rectangular shape in a plan view, and the flat portion extends over substantially the entire lower side portion. 7. The rear projection display device includes a screen frame and a fixture for the Fresnel lens sheet, wherein the Fresnel lens sheet is fitted into the screen frame from the inside, and a side of the Fresnel lens sheet is formed. The outer surface is abutted on the inner surface of the screen frame directly or via a predetermined member, and the inner surface of the side portion is attached to the screen frame by pressing the inner surface of the side portion with the fixing tool. 5. The rear projection display device according to 4. 8. The rear projection type display device according to claim 7, wherein a lenticular lens sheet is arranged close to the Fresnel lens sheet on an outer surface side of the Fresnel lens sheet. 9. The rear projection type display device according to claim 8, wherein a transparent panel is disposed on an outer surface side of the lenticular lens sheet in proximity to the lenticular lens sheet.