JP3797888B2 - Transmission type screen and projection type image display apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmissive screen on which image light is projected to display an image.
[0002]
[Prior art]
Conventionally, as a transmissive screen of a rear projection type image display device, a horizontal lenticular lens sheet in which horizontal lenticular lenses are arranged at equal intervals on a light incident surface, and a Fresnel lens in which light-emitting surfaces are arranged concentrically at equal intervals. There are a lens sheet and a lens sheet, and a vertical lenticular lens arranged at equal intervals on the light incident surface of the Fresnel lens sheet. The Fresnel lens refracts the light enlarged and projected by the projection lens optical system so as to be substantially parallel to the optical axis of the projection lens optical system, so that the image becomes bright even to the periphery of the screen. The horizontal lenticular lens acts to diffuse light incident through the Fresnel lens in the horizontal direction and widen the viewing range in the horizontal direction. The vertical lenticular lens acts to diffuse incident light in the vertical direction and widen the viewing range in the vertical direction.
[0003]
[Problems to be solved by the invention]
Moire occurs when a plurality of regularly arranged lens array elements overlap. The same applies to a transmissive screen composed of three elements of a horizontal lenticular lens, a Fresnel lens, and a vertical lenticular lens as array elements. Moire obstructs the image on the screen, and it is necessary to set each pitch so that moire is as inconspicuous as possible. Moire that must be taken into consideration in these three factors is (1) generated by horizontal lenticular lens and Fresnel lens, (2) generated by vertical lenticular lens and Fresnel lens, (3) horizontal lenticular lens and vertical lenticular lens There are lens intersections and those generated by Fresnel lenses. Since the horizontal lenticular lens and the vertical lenticular lens are orthogonal, generally no moire occurs between the two. FIG. 3 schematically shows an example of the moire (1). In the figure, the vertical line group indicates a horizontal lenticular lens, and the concentric circle group indicates a Fresnel lens. FIG. 3 shows a case where the moire is conspicuous, that is, the case where the horizontal lenticular lens and the Fresnel lens have the same pitch. FIG. 4 shows an example of the moiré of (2) above. In the figure, the horizontal line group indicates a vertical lenticular lens, and the concentric circle group indicates a Fresnel lens. The case of FIG. 4 is also the case where the moire is conspicuous, that is, the vertical lenticular lens and the Fresnel lens have the same pitch. Further, FIG. 5 is an explanatory diagram of the moiré of (3), in which the vertical line group is a horizontal lenticular lens, the horizontal line group is a vertical lenticular lens, the concentric circle group is a Fresnel lens lens, and the oblique line (dotted line) group is a horizontal lenticular A virtual diagonal line group connecting intersections of a lens and a vertical lenticular lens is shown. Moire is generated by the relationship between the pitch of the concentric circle group and the oblique line group. In FIG. 5, the upper right part from the center of the Fresnel lens is shown. Moire in this case is generated as a streak that stands out in the direction of approximately 45 ° on the upper right from the center of the Fresnel lens.
An object of the present invention is to reduce the moire of the above (1), (2) and (3) in a transmissive screen and to improve image quality.
The objective of this invention is providing the technique which can solve this subject.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention,
(1) In a transmission screen in which a vertical lenticular lens, a Fresnel lens, and a horizontal lenticular lens are arranged , the horizontal lenticular lens has a lenticular lens formed on one side of a horizontal lenticular lens sheet and is separate from the horizontal lenticular lens sheet. The vertical lenticular lens is disposed on the light exit side of the Fresnel lens formed on the lens sheet, and is formed of a convex lens, and between the light incident side of the Fresnel lens or between the Fresnel lens and the horizontal lenticular lens. arranged, the vertical lenticular lens, the Fresnel lens, the pitch of the horizontal lenticular lens and Pv, Pf, and Ph respectively, and an integer of 1 or more and n, Pk = 1 / {( 1 / Ph) 2 + (1 / Pv) ^2} was ^1/2 Come, the Pk, Pf is, in the case of Pk / Pf> 1, Pk / Pf = n + 0. 3 to 0.7 and Pf / Pk> 1, Pf / Pk = n + 0 . It met from 3 to 0.7, a configuration for reducing the moire caused by the above vertical lenticular lens and the horizontal lenticular lens imaginary diagonal group and the Fresnel lens connecting the intersections between the.
(2) In the above (1), when Pf / Ph> 1, Pf / Ph = n + 0 . 3 to 0.7 and when Ph / Pf> 1, Ph / Pf = n + 0 . 3 to 0.7 and f / Pv> 1, Pf / Pv = n + 0 . If Pv / Pf> 1, then Pv / Pf = n + 0 . Satisfy 3 to 0.7.
(3) The projection type image display device includes the transmission screen of (1) or (2).
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a first embodiment of the present invention. In this embodiment, the vertical lenticular lens surface is provided on the light incident side of the Fresnel lens sheet. The horizontal lenticular lens pitch is about 0.155 mm, the vertical lenticular lens pitch is about 0.097 mm, and the Fresnel. The pitch of the lenses is approximately 0.060 mm. When the pitch of the Fresnel lens is relatively 1.00, the pitch of the horizontal lenticular lens is relatively 2.58, and the pitch of the vertical lenticular lens is relatively 1.62. In FIG. 1, 1 is an image display element such as a liquid crystal panel, 2 is a projection lens optical system, 3 is a Fresnel lens sheet, 6 is a horizontal lenticular lens sheet, 4 is a vertical lenticular lens, 5 is a Fresnel lens, and 7 is a horizontal lenticular lens. , 8 is a diffusing material such as glass beads for diffusing light, 10 is a transmissive screen, Pv is the pitch of the vertical lenticular lens, Pf is the pitch of the Fresnel lens, and Ph is the pitch of the horizontal lenticular lens. Image light formed by the image display element 1 is enlarged by the projection lens optical system 2 and projected onto the transmission screen 10. In the screen 10, the projection light is diffused in the vertical direction by the vertical lenticular lens 4 and is incident on the Fresnel lens 5 in a state where the viewing range in the vertical direction is widened. In the Fresnel lens 5, the projection lens optical system The light is emitted in a state of being substantially parallel to the optical axis 2. The emitted light further enters the horizontal lenticular lens 7 and is emitted in a state where the horizontal lenticular lens 7 diffuses in the horizontal direction and widens the viewing range in the horizontal direction. The viewer views the emitted light from the horizontal lenticular lens 7 as a projection image. In the case of the first embodiment, Ph / Pf = 2.58, Pv / Pf = 1.62, Pk = 1.37 (Pk: virtual diagonal line connecting the intersections of the horizontal lenticular lens and the vertical lenticular lens) Group pitch Pk = 1 / {(1 / Ph) ² + (1 / Pv) ² } ^1/2 ), each within the limited range of the invention.
[0006]
FIG. 2 is a configuration example of a rear projection type image display apparatus using the transmission screen shown in FIG.
In FIG. 2, 1 is an image display element such as a liquid crystal panel, 2 is a projection lens optical system, 10 is a transmission screen, 15 is a light source unit, 20 is a mirror, and 30 is a drive circuit for the image display element. The light from the light source unit 15 is modulated by the image display element 1 and emitted as image light, magnified by the projection lens optical system 2, reflected by the mirror 20, and then projected from the back onto the transmission type screen 10. Is done.
FIG. 6 is a simulation result on the moire characteristics of the transmission screen of the first embodiment. According to this, (1) the moire generated by the horizontal lenticular lens and the Fresnel lens, and (2) the moire generated by the vertical lenticular lens and the Fresnel lens, (3) the intersection of the horizontal lenticular lens and the vertical lenticular lens All of the moire generated by the connected virtual diagonal line group and the Fresnel lens is small, and it is in an allowable range as a whole. For comparison, FIG. 7 shows a case where Pf = 1.00, Ph = 1.41, Pv = 1.41, that is, Ph / Pf = 1.41, Pv / Pf = 1.41, Pk = 1. The simulation result of the moire characteristic of the screen in the case of 0.00 is shown. In this case, both the Ph / Pf value and the Pv / Pf value are within the limited range of the invention. For this reason, the moiré of the above (1) and (2) is small, but Pk / Pf = 1.00, which is outside the range limited as the invention. For this reason, there are many moiré of said (3). Moire is conspicuous overall.
[0007]
FIG. 8 shows a simulation result of moire characteristics in the configuration of the second embodiment of the present invention. In the second embodiment, the transmission screen is composed of a Fresnel lens and a horizontal lenticular lens. The illustration of the configuration of the second embodiment is omitted. In the case of this configuration, the moiré is only the moiré (1). The simulation conditions are a horizontal lenticular lens pitch Ph = 1.60 and a Fresnel lens pitch Pf = 1.00. Since Ph / Pf = 1.60, which is within the limited range of the invention, there is little moire. For comparison, FIG. 9 shows a simulation result of moire characteristics when Pf = 1.00 and Ph = 1.20, that is, when Ph / Pf = 1.20. In this case, the Ph / Pf value is out of the limited range of the invention, and the moiré (1) is large.
The lens pitch range of the present invention was obtained based on simulation and confirmation experiments. The outline is as follows.
[0008]
In general, assuming that the pitches of the two lens arrangement elements are P1 and P2, respectively, the relationship with the pitch Pm of the moire generated by these is as follows:
[0009]
1 / Pm = | n1 / P1-n2 / P2 | (n1 and n2 are natural numbers) (Equation 1)
It is represented by This equation further
[0010]
1 / Pm = | (P2 / P1-n2 / n1) · n1 / P2 |
And can be transformed. As apparent from Equation 2, the smaller n1 and n2 are, and the closer P2 / P1 is to n2 / n1, the larger Pm becomes and the moire is more conspicuous. Therefore, in order to obtain a screen configuration in which moire is not conspicuous, it is necessary to make n1 and n2 large values, and to make the values of P1 and P2 so that P2 / P1 does not become a value close to n2 / n1. In order to obtain the pitch ratio P2 / P1 where the moire is not conspicuous, the moire for the combination of the values of n1 and n2 is evaluated. FIG. 10 shows the value of n2 / n1 when both n1 and n2 are changed within the range of 1 to 10. Each value is rounded off to the third decimal place. Since the relationship of P2 / P1 = n2 / n1 is assumed, n2 / n1 in FIG. 10 indicates a pitch ratio P2 / P1 where moire may be noticeable. As the procedure, moire evaluation was performed by simulation and confirmation experiment in order from the range of 1.00 ≦ n2 / n1 ≦ 2.00 underlined. As a result, the ratio Ph / Pf between the horizontal lenticular lens pitch Ph and the Fresnel lens pitch Pf, which allows the moire to be inconspicuous, is in the range of about 1.3 to about 1.7. The same applies to the case where the lens pitch ratio Ph / Pf exceeds 2.00. If the portion below the decimal point of the pitch ratio value is in the range of approximately 0.3 to approximately 0.7, moire is acceptable. It becomes inconspicuous. The same applies to the case where the lens pitch ratio Ph / Pf is smaller than 1, that is, the case where the pitch ratio Pf / Ph opposite to Ph / Pf exceeds 1.
The same applies to the relationship between the pitch Pv of the vertical lenticular lens and the pitch Pf of the Fresnel lens.
[0011]
On the other hand, the intersection group of the horizontal lenticular lens and the vertical lenticular lens and the moire generated by the Fresnel lens are as follows. That is, between the pitch Ph of the horizontal lenticular lens, the pitch Pv of the vertical lenticular lens, and the pitch Pk of a virtual diagonal line group connecting the intersections of the horizontal lenticular lens and the vertical lenticular lens,
[0012]
Pk = 1 / {(1 / Ph) ² + (1 / Pv) ² } ^1/2 (Equation 3)
Therefore, the condition for making the moire due to the pitch Pf of the Pk and the Fresnel lens inconspicuous is, when Pk / Pf> 1, the fractional part of the value of Pk / Pf is approximately 0.3 to approximately 0.00. When Pf / Pk> 1, it means that the fractional part of the value of Pf / Pk is in the range of about 0.3 to about 0.7.
[0013]
According to the above embodiment, in the transmission screen, (1) moire generated by the horizontal lenticular lens and the Fresnel lens, (2) moire generated by the vertical lenticular lens and the Fresnel lens, and (3) vertical to the horizontal lenticular lens. Image quality can be improved by reducing the moire generated by the virtual diagonal line group connecting the intersections of the lenticular lenses and the Fresnel lens.
[0014]
In the first embodiment, the vertical lenticular lens is provided on the light incident surface side of the Fresnel lens sheet. In addition, the vertical lenticular lens is provided as a single sheet, the light incident surface side of the Fresnel lens lens sheet, Alternatively, it may be arranged between the Fresnel lens lens sheet and the horizontal lenticular lens sheet, or at a position such as the light emitting side of the horizontal lenticular lens sheet, and the vertical lenticular lens surface is the light incident surface and light emitting surface of the vertical lenticular lens sheet It may be provided on either side. Further, the vertical lenticular lens and the vertical lenticular lens sheet may not be provided.
[0015]
【The invention's effect】
According to the present invention, it is possible to reduce the moire of the transmissive screen and to display a good image.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration example of a rear projection type image display apparatus using a transmission type screen.
FIG. 3 is an explanatory diagram of moire generated by a horizontal lenticular lens and a Fresnel lens.
FIG. 4 is an explanatory diagram of moire generated in a vertical lenticular lens and a Fresnel lens.
FIG. 5 is an explanatory diagram of moiré that occurs between an intersection group of horizontal lenticular lenses and vertical lenticular lenses, and a Fresnel lens.
FIG. 6 is a diagram showing a simulation result of moire according to the first embodiment of the present invention.
FIG. 7 is a simulation result example in the case of a large moire.
FIG. 8 is a diagram showing a simulation result of moire according to the second embodiment of the present invention.
FIG. 9 is an example of a simulation result when a large moire appears.
FIG. 10 is a diagram illustrating a value of a lens pitch ratio when a large moire occurs.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image display element, 2 ... Projection lens optical system, 3 ... Fresnel lens lens sheet, 4 ... Vertical lenticular lens, 5 ... Fresnel lens, 6 ... Horizontal lenticular lens sheet, 7 ... Horizontal lenticular lens, 8 ... Light diffusing material, DESCRIPTION OF SYMBOLS 10 ... Transmission type screen, 15 ... Light source unit, 20 ... Mirror, 30 ... Image display element drive circuit Pv ... Pitch of vertical lenticular lens, Pf ... Pitch of Fresnel lens, Ph ... Pitch of horizontal lenticular lens.

Claims (3)

In a transmission screen in which a vertical lenticular lens , a Fresnel lens and a horizontal lenticular lens are arranged,
The horizontal lenticular lens is disposed on the light emitting side of the Fresnel lens formed on a lens sheet different from the horizontal lenticular lens sheet, with the lenticular lens formed on one side of the horizontal lenticular lens sheet,
The vertical lenticular lens is a convex lens, and is disposed on the light incident side of the Fresnel lens or between the Fresnel lens and the horizontal lenticular lens,
The pitches of the vertical lenticular lens, the Fresnel lens, and the horizontal lenticular lens are Pv, Pf, and Ph, respectively, and an integer of 1 or more is n, and Pk = 1 / {(1 / Ph) ² + (1 / Pv) ² } when ^1/2, the Pk, Pf is,
For Pk / Pf> 1, Pk / Pf = n + 0 . Meets 3-0.7,
In the case of Pf / Pk> 1, Pf / Pk = n + 0 . Meets 3-0.7,
Transmission screen, characterized in that the configuration for reducing the moiré generated by the virtual diagonal line group and said Fresnel lens connecting the intersections between the vertical lenticular lens and the horizontal lenticular lens. The transmissive screen according to claim 1,
In the case of Pf / Ph> 1, Pf / Ph = n + 0 . Meets 3-0.7,
In the case of Ph / Pf> 1, Ph / Pf = n + 0 . Satisfy 3 to 0.7, and
For Pf / Pv> 1, Pf / Pv = n + 0 . Meets 3-0.7,
In the case of Pv / Pf> 1, Pv / Pf = n + 0 . A transmission screen satisfying 3 to 0.7.   A projection-type image display device comprising the transmissive screen according to claim 1.

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