JP2922233B2 - Transmissive screen for LCD projector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive screen used for a liquid-phase projector, and more particularly, to a liquid crystal in which the occurrence of moire caused by interference between pixels projected on the screen and the screen is suppressed. The present invention relates to a transmission screen for a projector.

[Conventional technology]

As the liquid crystal projector, a reflection type projector that projects an image from the front of a screen and a transmission type projector that projects an image from the back are known.

The reflection type liquid crystal projector can project onto a wall surface of a room, a reflection diffusion plate, or the like, and can be easily installed and used even in a wide place.

A transmissive liquid crystal projector can obtain a clear image even when the surrounding environment is bright. In addition, since liquid crystal is used, a thin set can be made. In this transmission type liquid crystal projector, a transmission type screen in which a plurality of lens sheets are combined as necessary is used as a screen.

Conventionally, this type of transmissive screen is configured by combining a Fresnel lens sheet, a lenticular lens sheet, a prism lens sheet, a diffusion sheet, and the like. Among them, a Fresnel lens has the advantages of a bright screen surface and a wide viewing angle. Many sheets combine a sheet and a lenticular lens sheet.

[Problems to be solved by the invention]

However, unlike liquid crystal projectors, which project diffuse light from a CRT, which is a type of self-luminous element, light source light is projected through a liquid crystal having segments separated by a pixel frame. Appears clearly.

Therefore, when projected on a conventional transmissive screen,
Since the shadow of the pixel frame interferes with the concentric stripes of the Fresnel lens and the vertical stripes of the lenticular lens, there is a problem that extremely remarkable moire occurs and the image quality is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a transmissive screen for a liquid crystal projector which prevents the occurrence of moiré when an image is projected from the liquid crystal projector and has no deterioration in image quality. .

[Means for solving the problem]

In order to solve the above-mentioned problems, a transmission screen for a liquid crystal projector according to the present invention is a transmission screen for a liquid crystal projector in which projection light of the liquid crystal projector is incident from the back and an image is observed from the front, wherein the transmission screen is At least one Fresnel lens sheet having a concentric Fresnel lens portion formed thereon is disposed on the light source side, and at least one lenticular lens sheet having a lenticular lens portion formed thereon is disposed on the observation side; Part on the emission side, and the Fresnel lens sheet and the lenticular lens sheet are arranged to face each other, and the pitch of the Fresnel lens part is 1 / the pitch of a pixel frame projected on the transmission screen by the liquid crystal projector. Formed so as to be smaller than 3.3 times, and The pitch of the lenticular lens portion is smaller than 1 / 3.3 times the pitch of the pixel frame projected on the transmissive screen by the liquid crystal projector, or 1 / 2.35 to 1 / 2.65 times or 1 / 1.35 to 1 / 1.65. It is configured so as to be a magnification that is twice and deviates from 1 / 1.5 times, or 1.35 times to 1.45 times.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings and the like based on embodiments.

FIG. 1 is a diagram schematically showing an embodiment of a transmission screen for a liquid crystal projector according to the present invention.

In this embodiment, the liquid crystal projector 1
The case where the image is projected on the 50-inch transmission screen 2 will be described.

The liquid crystal projector 1 uses a square having a projection pixel frame pitch P1 = 2.9 mm when projected on the transmission screen 2.

The transmission screen 2 includes a Fresnel lens sheet 21 on the light source side and a lenticular lens sheet 22 on the observation side.

The Fresnel lens sheet 21 is for making the projection light from the liquid crystal projector 1 substantially parallel, and has a pitch P2 = 0.112 mm (1 / 25.9 of the projection pixel frame pitch P1) on the emission side.
) Lens portion 21a is formed.

The lenticular lens sheet 22 is for diffusing the projection light in the horizontal direction to enlarge the viewing angle, and has a pitch P3 = 0.85 mm on the incident side (1 / 3.41 times the projection pixel frame pitch P1).
Is formed.

When an image was projected from the liquid crystal projector 1 onto such a transmissive screen 2, a good image could be observed without occurrence of moire.

Next, when the pitch P3 of the lens portion 22a of the lenticular lens sheet 22 was appropriately changed using the liquid crystal projector 1 and the occurrence of moire was examined, the results are as shown in Table 1 below.

In Table 1, the left column shows the magnification α (= P3 / P1) of the pitch P3 of the lens unit 22a with respect to the projection pixel frame pitch P1, and the right column shows the evaluation.

When using a liquid crystal projector, moire is usually
This is caused by the relationship between the pixel frame pitch projected on the transmissive screen and the pitch of the lens units (lenticular lens, Fresnel lens, prism lens, etc.).

This moiré is remarkable and has a large period when the pitch of the projection pixel frame and the pitch of the lens unit are equal. Therefore, even when the pitches of the two have a relationship of twice, three times,..., Moire having a large period occurs, and the pitches deviate from the relationship of n times (n is an integer) or 1 / n times. Moiré weakens.

Further, as the value of n multiplied by n times or 1 / n times increases, the density of moiré becomes lower. When the value of n becomes 4 or more, it becomes a practically acceptable level.

Further, from the viewpoint of pixel resolution, the smaller the pitch of the lens unit is, the better the pitch of the lens unit is than the projection pixel frame pitch.

From the above, it can be seen that when the pitch of the lens portion is smaller than 1 / 3.3 times the projection pixel frame pitch, a good quality image can be obtained.

On the other hand, when the pitch of the projection pixel frame is reduced, the pitch of the lens unit must be reduced accordingly.

However, when the pitch of the lens portions is reduced, it is necessary to reduce the thickness of the lens sheet, and it is not possible to manufacture an industrially inexpensive transmission screen due to various restrictions.

Therefore, a lens sheet in which the pitch of the lens unit is 1 / 2.35 to 1 / 2.65 times the projection pixel frame pitch, or 1 / 1.35 to 1 / 1.65 times is desirable from the viewpoint of image quality. At this time,
Since a moire of 1/3 times occurs every other time around 1 / 1.5 times, it is better to set a magnification slightly deviated from 1 / 1.5 times.

In addition, when the projection pixel frame pitch is very small, the moiré is inconspicuous if the pitch of the lens unit is set to 1.35 to 1.45 times the projection pixel frame pitch.

Various modifications can be made without being limited to the embodiment described above.

As long as the relationship between the pitch of the pixel frame to be projected and the pitch of the lens unit satisfies the above-described condition, the lens sheet may be a prism lens sheet or another sheet.

In the above-described embodiment, the moiré generated due to the relationship between the pitch of the pixel frame projected from the liquid crystal projector and the pitch of the lens unit of the transmission screen has been described. It is preferable to use a known method such as mixing a diffusing agent into the sheet to suppress the occurrence of moire. .

〔The invention's effect〕

As described in detail above, according to the present invention, when an image is projected from a liquid crystal projector onto a transmission screen, moire does not occur, so that a transmission screen for a liquid crystal projector with good image quality can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an embodiment of a transmission screen for a liquid crystal projector according to the present invention. 1 LCD projector 2 Transmissive screen 21 Fresnel lens sheet 22 Lenticular lens sheet

Claims (1)

(57) [Claims] 1. A transmissive screen for a liquid crystal projector, in which projection light from the liquid crystal projector is made incident from the back and an image is observed from the front, wherein the transmissive screen has at least one concentric Fresnel lens portion. The Fresnel lens sheet is disposed on the light source side, and at least one lenticular lens sheet on which the lenticular lens part is formed is disposed on the observation side. The Fresnel lens part is an emission side, and the Fresnel lens sheet and the A lenticular lens sheet is disposed so as to face, and a pitch of the Fresnel lens portion is formed to be smaller than 1 / 3.3 times a pitch of a pixel frame projected on the transmission screen by the liquid crystal projector, and The pitch of the lenticular lens section is controlled by the liquid crystal projector. Or less than 1 / 3.3 times the pitch of pixels frame projected on the over-shape the screen, 1 / 2.35 to 1 / 2.65
A transmission screen for a liquid crystal projector, wherein the transmission screen is formed so as to have a magnification of 1 / 1.35 to 1 / 1.65 and deviating from 1 / 1.5, or 1.35 to 1.45.