JP2006301430A - Transmissive screen and projection type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a transmissive screen and a projection type display apparatus with which an observer can observe a video even when the observer moves in a vertical direction by expanding a visibility angle in the vertical direction and to obtain a projection type display. <P>SOLUTION: A cylindrical lens sheet 5 formed by connecting cylindrical lenses 5a in the vertical direction on a light exit surface expands a light beam projected from a projector 1 and a diffusion sheet 6 diffuses the light beam projected from the light exit surface of the cylindrical lens sheet 5. Consequently the visibility angle in the vertical direction is expanded, and even when the observer slightly moved in the vertical direction, the observer can observe a video. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmissive screen and a projection display device that form an image of a light beam emitted from a light emitter such as a projector and display it.

A transmissive screen typified by a rear-projection projector has a Fresnel lens screen that collimates the light emitted from the light source toward the viewer, a lenticular screen that adjusts the light distribution characteristics of the light, and a diffusion that diffuses the light. It consists of a sheet.
Therefore, the light distribution characteristic of the light beam depends on the lenticular screen, and the following Patent Document 1 discloses a lenticular screen in which lens sheets having a lens action are arranged in the horizontal direction.
Patent Document 2 below discloses a lenticular screen in which two orthogonal lens sheets are arranged.

The observer who observes the image displayed on the transmission screen generally moves in the horizontal direction but does not move in the vertical direction. Are different in the vertical and left-right directions.
That is, a lenticular screen of a transmissive screen generally has a horizontal viewing angle (light distribution characteristic) because a lenticular lens (for example, a cylindrical lens) that spreads light distribution in the horizontal direction is formed on the light incident surface. Although the vertical light distribution is not spread by the lenticular lens but spread only by diffusion of the diffusion sheet, the half width at half maximum (the angle from the center at which the brightness is halved) is Only about 10 degrees, and the viewing angle is extremely narrow compared to the horizontal direction.
Note that it is not preferable to widen the vertical viewing angle with the diffusion sheet because it causes blurring of the image.

Japanese Patent Laid-Open No. 11-38513 (FIG. 1) Japanese Patent Laid-Open No. 5-158155 (FIG. 1)

  Conventional transmission screens are configured as described above, so the vertical viewing angle is extremely narrow compared to the horizontal direction, and if the observer moves in the vertical direction, the video cannot be observed. was there.

  The present invention has been made to solve the above-described problems, and has a transmission screen and a projection type capable of observing an image even when an observer moves in the vertical direction by widening the viewing angle in the vertical direction. An object is to obtain a display device.

  In the transmissive screen according to the present invention, a cylindrical lens sheet having a cylindrical lens connected in the vertical direction on the light exit surface spreads light rays emitted from the light emitter, and a diffusion sheet is emitted from the light exit surface of the cylindrical lens sheet. The light beam is diffused.

  According to the present invention, the cylindrical lens sheet in which the cylindrical lenses are connected in the vertical direction on the light exit surface spreads the light emitted from the light emitter, and the diffusion sheet reflects the light emitted from the light exit surface of the cylindrical lens sheet. Since it is configured to diffuse, the viewing angle in the vertical direction is widened. As a result, there is an effect that an image can be observed even if the observer moves slightly in the vertical direction.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a projection display apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a perspective view showing a part of a transmissive screen according to Embodiment 1 of the present invention.
In the figure, a projector 1, which is a light emitter, includes a projection optical system 1a, a light valve 1b, and an illumination optical system 1c, and irradiates a Fresnel optical element 3 of a transmissive screen 2 with light rays for image projection.
The transmission screen 2 includes a Fresnel optical element 3, a base 4, a cylindrical lens sheet 5 that is a lens element, and a diffusion sheet 6.

The Fresnel optical element 3 has a structure in which a plurality of Fresnel prisms 3a having a refracting surface that refracts a light beam irradiated from the projector 1 and a reflecting surface that reflects a light beam refracted by the refracting surface are arranged in a sawtooth shape.
The substrate 4 is a sheet-like resin thin plate or glass thin plate that transmits light, and holds the Fresnel optical element 3.
The cylindrical lens sheet 5 has a cylindrical lens 5a connected in the vertical direction on the light exit surface, and has a function of spreading the light beam transmitted through the substrate 4 in the vertical direction.
The diffusion sheet 6 has a function of diffusing light emitted from the light exit surface of the cylindrical lens sheet 5.

Next, the operation will be described.
In the first embodiment, the light distribution in the vertical direction is determined by the light distribution characteristics of the cylindrical lens sheet 5 and the diffusion sheet 6.
Therefore, it is necessary to obtain a total light distribution characteristic as the transmissive screen 2 by multiplying the light distribution characteristic obtained from the lens shape of the cylindrical lens 5a in the cylindrical lens sheet 5 and the light distribution characteristic of the diffusion sheet 6. .

First, the lens shape of the cylindrical lens 5a will be described.
FIG. 3 is a schematic diagram showing the cylindrical lens 5 a in the cylindrical lens sheet 5.
Here, for simplification of explanation, a part of an elliptical arc is considered. The z axis is taken as the major radius of the cylindrical lens 5a, and the direction in which the light beam travels is positive.
Further, here, in order to consider a cylindrical lens 5a connected in the vertical direction (a structure in which the cross-sectional cylindrical lenses 5a having an elliptical cross section are stacked in the y-axis direction), the y-axis is the vertical direction and x is the horizontal direction. It becomes.
In the example of FIG. 3, the cylindrical lenses 5a are arranged in the vertical direction, but the arrangement direction may be a horizontal direction. Needless to say, the same arrangement can be made with an array of microlens arrays instead of a one-dimensional lens. Needless to say, second-order aspheric surfaces such as ellipses, second-order parabolas, hyperboloids, and higher-order aspheric surfaces can be considered in the same manner.

The arc of an ellipse is a function determined by three degrees of freedom: a long radius a, a short radius b, and a size (lens pitch) p to be cut out.
In the case of an ellipse, the arc can be expressed by the following formula (1).
f (z, y; a, b, p) = (z / a) ² + (y / b) ² −1 = 0 (1)
−p / 2 ≦ y ≦ p / 2
However, since the light distribution characteristic depends only on the inclination of the arc and not on the size, it does not change with respect to scale conversion (similar deformation). That is, since the degree of freedom of scale conversion is 1, the degree of freedom of light distribution characteristics is 2.
Specifically, for example, the similarity magnification p can be designated by the lens pitch p, and arc shapes a / p and b / p can be designated.
The lens pitch p is better when it is smaller than the projected pixel size. For example, if the pixel is 1.0 mm, it is preferable that at least p <0.5 mm.

For example, when a parallel light beam is incident on the cylindrical lens 5a, if the cylindrical lens 5a is nearly flat, the role of the lens (the function of bending the light beam) is small, so that the light beam is emitted without being bent so much. On the other hand, if the curvature of the lens is large, the light beam is greatly bent and emitted.
When the light beam is bent greatly, it means that the angular distribution of light distribution is wide, and when it is not bent very much, it means that the angular distribution of light distribution is narrow and bright in the front.
In general, the projector 1 is desired to have a bright screen with a wide viewing angle. However, due to the law of energy conservation, the two are in a trade-off relationship, and this distribution is difficult.

The screen brightness is often expressed by a screen gain, which is defined by “ratio of luminance under conditions equivalent to the luminance projected on the complete diffusion surface”. Generally, the front (normal direction) is the brightest, so this is sometimes called peak gain.
The viewing angle is generally expressed as an angle that is 1/2 (α), 1/3 (β), or 1/10 (γ) of the peak gain.
FIG. 11 is an explanatory diagram showing an example of the viewing angle α and the viewing angle γ with the screen gain of a certain diffusion sheet.

Here, as shown in FIG. 4, when an ellipse having a major radius of a and a minor radius of b is cut with a lens pitch p and the thickness of the arc (direction perpendicular to the pitch) is d, as shown in FIG. When the radius a of the cylindrical lens 5a is reduced (a ₁ <a ₂ ), the lens surface of the cylindrical lens 5a approaches flat, so that the lens action of the cylindrical lens 5a is reduced, and more light is emitted from the front. For this reason, the screen gain is expected to increase.
On the other hand, as shown in FIG. 5, when the lens pitch p is reduced (p ₁ <p ₂ ), the flat portion of the cylindrical lens 5a is used relatively much, so that the screen gain is expected to increase. .
Therefore, in order to obtain a lens having a large screen gain, the major radius a and the lens pitch p should be made as small as possible with respect to the minor radius b. In other words, this means that the thickness d of the arc is as small as possible with respect to the lens pitch p.

In general, the normal of the surface is obtained from the differentiation of the arc f (see FIG. 3). Assuming that the inclination of the surface or the inclination of the normal is θ, the inclination of the normal is expressed as follows.
θ = tan ⁻¹ (∂ _y f / ∂ _z f) (2)
However, ∂ _y partial differential of y, ∂ _z denotes the partial derivative of z. The maximum inclination θ _max of the lens surface is the inclination of the end of the lens pitch p as shown in FIG.
For example, in the case of an ellipse, the maximum inclination θ _max of the lens surface is expressed by the following equation (3).
θ _max (p / b, a / b)
= Tan ^-1 ([(a / b) (p / 2b)] / (1- (p / 2b) ² ) ^1/2 ))
(3)
From equation (3), it can be seen that the variable is represented only by the ratio of p / b and a / b. The tilt of the lens surface is represented by θ, and the tilt of the light beam is represented by φ.

Light rays incident at an angle phi _in, as shown in FIG. 6, the lens surface of the cylindrical lens 5a, is bent by refraction phenomenon of light. At this time, the refractive index on the lens side is n _in and the refractive index outside the lens is n _out . However, the refractive index is constant and does not change with position.
For a light beam refracted and emitted by the cylindrical lens 5a (when the total reflection condition is not satisfied), assuming that the refractive indexes n _in and n _out are constant, the inclination φ _out is expressed as follows.
φ _out (θ; φ _in )
= Sin ⁻¹ ((n _in / n _out ) sin [θ−φ _in ]) − θ
(4)
Note that the front of the cylindrical lens sheet 5, usually, since the Fresnel optical element 3 is arranged, the angle of incidence phi _in will usually approximately 0 degrees.

Therefore, when equation (4) is solved in reverse, equation (5) below is obtained.
θ (φ _out ; φ _in )
= Tan ⁻¹ ([n _in / n _out ) sinφ _in + sinφ _out ]
/ [(N _in / n _out ) cos φ _in −cos φ _out ])
(5)
This is converted inclination phi _out and theta, i.e. the inclination theta of inclination phi _out and the lens of the emission light when the angle of incidence phi _in are the same, it means that the determined uniquely.

As described above, if the cylindrical lens 5a is nearly flat, the role as a lens (function to bend light) is small, and thus light rays are emitted without being bent so much.
On the other hand, if the curvature of the lens is large, the light beam is greatly bent and emitted.
Since this relationship is uniquely determined, the maximum angle φ _max of the emitted light is the position of the maximum inclination θ _max of the lens surface (see FIG. 7).
However, in the case of θ> θ _{c where} the total reflection condition is satisfied, there is an exception that does not act as a lens because it is not refracted and emitted out of the cylindrical lens 5a. However, θ _c = sin ⁻¹ (n _out / n _in ). That is, the maximum inclination θ _max of the emitted light is θ _max <φ _c . However, φ _c = π / 2−θ _c .

In summary, for example, in the case of a quadratic curved surface (ellipse), if the following two are determined, the lens shape (excluding p times the similar deformation) is uniquely determined.
(1) Arc thickness d (ie, d / p) with respect to lens pitch p that governs the magnitude of screen gain
(2) The maximum inclination θ _{max of} the lens governing the maximum spread of the light distribution
As described above, in the case of a quadratic curved surface (ellipse), the similar magnification and the lens shape may be designated by the lens pitch p by a / p and b / p, which correspond to 1: 1. Therefore, even if the former (d / p, θ _max ) is specified for the lens shape measurement and the latter (a / p, b / p) is specified for the lens shape design, these are uniquely determined.

When the lens shape of the cylindrical lens 5a is designated as described above, the screen gain can be calculated.
8, 9, and 10 show the angle dependence of the screen gain by a single lens, the horizontal axis is the angle from the screen normal, and the vertical axis is the screen gain.
The lens parameters are as follows.
u (d / p, θ _max ) = (0.117, 26.8 degrees)
v = (0.109, 24.0)
w = (0.162, 36.2)
x = (0.159, 42.1)
n = (0.135, 35.8)
l = (0.106, 36.9)
m = (0.119, 36.5)
FIG. 46 shows a calculation example when the refractive index n _in = 1.550, the refractive index n _out = 1.000, and the incident angle φ _in = 0.0.
As can be seen from the calculation example of FIG. 46, if d / p is small, the peak gain (maximum value g _{max of} screen gain) is large, and if θ _max is large, the angular spread of the light distribution characteristic is large.

From the calculation examples of u and v in FIG. 8, it can be seen that the maximum angle of the light distribution characteristic is φ _max <20 degrees, the angle range is narrow, and the peak gain is large (g _max > 6).
9 shows that the maximum angle of the light distribution characteristic is φ _max > 20 degrees, and the angle range is widened, but the peak gain is small (g _max < 6).
As a result of detailed studies, n, l, and m in FIG. 10 are obtained when, for example, the maximum angle φ _max > 20 degrees of the light distribution characteristic is obtained and a large peak gain (g _max > 6) is successfully obtained. This is a calculation example (success conditions will be described later). In this case, a bright screen having a wide viewing angle and a wide light distribution characteristic can be obtained.

As described above, in actuality, not only the light distribution characteristics of the lens itself but also the light distribution characteristics of the diffusion sheet 6 are observed, so it is necessary to consider the light distribution characteristics of the diffusion sheet 6 as well.
FIG. 11 is an explanatory diagram showing the light distribution characteristics of a diffusion sheet having a haze value of 85% and a thickness of 2 mm, where the horizontal axis is normalized by the angle from the screen normal, and the vertical axis is normalized by the peak gain (= 1). Screen gain.
Thus, the diffusion sheet 6 having a haze value of 85% has a spread of about 10 degrees for α and about 22 degrees for γ. Although not shown, the diffusion sheet 6 having a haze value of 80% has a spread of about 9 degrees for α and about 19 degrees for γ. This is not a negligible amount compared to the light distribution characteristics of a single lens.

12, 13 and 14 show the total screen gain in which the light distribution characteristics of both the cylindrical lens 5a and the diffusion sheet 6 are considered.
As for the overall screen gain, the light distribution characteristic of the single lens (FIGS. 8 to 10) is smoothed more smoothly by the light distribution characteristic of the diffusion sheet 6 (see FIG. 11). That is, the total screen gain can be approximated as the product of the light distribution characteristic of the lens alone and the light distribution characteristic of the diffusion sheet 6. Hereinafter, the screen gain of a single lens is expressed as g, and the total screen gain is expressed as g ′.

Each of the curves in FIGS. 12, 13 and 14 is a calculated value, and the + mark indicates an actual measurement value obtained by actually making a trial manufacture of the cylindrical lens 5a and combining it with the diffusion sheet 6 having a haze value of 85% and a thickness of 2 mm. Show.
Note that the refractive index has a lens pitch of 89 microns (the lens pitch is not affected by the scale conversion) as in the design value. Multiple measurement values at the same angle indicate variations in measurement. Since the light distribution characteristic of the diffusion sheet 6 has a wide skirt (up to 90 degrees), the overall screen gain is cut off as seen by the lens alone, and is not noticeable in the figure.

As described above, in the example (u, v) where the maximum angle of the single lens is φ _max <20 degrees, the total peak gain becomes large (g ′ _max > 4).
In the example (x, w) where the maximum angle of the single lens is φ _max > 20 degrees, the total peak gain is small (g ′ _max <4).
14, n, l, and m are the results of a detailed study, and even when the maximum angle φ _max > 20 degrees of the single lens is successfully obtained, a large peak gain (g ′ _max > 4) is successfully obtained. (Success conditions will be described later).

In the gain chart of a single lens, the conventional one with a large cut-off has a small peak gain and the one with a small cut-off has a large peak gain, but the lens surface shape of the cylindrical lens 5a is 0.106 <d / p. By satisfying the conditions of <0.135 and 35.8 degrees <θ _max <36.9 degrees, it is possible to cause the cutoff to be large and the peak gain to be large. If the above conditions are not satisfied, it goes without saying that the above-mentioned effects are not exhibited, and the same characteristics as in the conventional case are obtained.

  As is apparent from the above, according to the first embodiment, the cylindrical lens sheet 5 having the cylindrical lens 5a connected in the vertical direction on the light exit surface spreads the light beam irradiated from the projector 1, and diffuses the sheet 6. Is configured to diffuse the light beam emitted from the light exit surface of the cylindrical lens sheet 5, so that the viewing angle in the vertical direction is widened, so that an image can be observed even if the observer moves slightly in the vertical direction. There is an effect that can be done.

Further, according to the first embodiment, the cylindrical lens 5a has a curve satisfying the conditions of 0.106 <d / p <0.135 and 35.8 degrees <θ _max <36.9 degrees. Since it is configured so that the shape is expressed, there is an effect that it is possible to obtain a transparent type screen that is bright and has a wide viewing angle.

  In the first embodiment, the light beam irradiated from the projector 1 is shown incident on the Fresnel optical element 3, but the light beam irradiated from the projector 1 is applied to the reflecting mirror 7 as shown in FIG. The light beam reflected and reflected by the reflecting mirror 7 may be incident on the Fresnel optical element 3.

Embodiment 2. FIG.
In the first embodiment, the cylindrical lens 5a is shown as a convex lens (see FIG. 7). However, the cylindrical lens 5a may be a concave lens as shown in FIG. 16, and the light distribution characteristic is changed. Absent. This is because the inclination of the lens surface is obtained from the differentiation of the arc f. In other words, the integral of the inclination of the lens surface is an arc, and there is an indefinite integration constant, so the light distribution does not change even if it is discontinuous like a convex, concave, or Fresnel lens.
However, although the position of the focal point S in the case of the convex lens and the position of the focal point S in the case of the concave lens are different, the lens pitch p is smaller than the projected one pixel and is about p <0.5 mm. When viewed from a distant observer, the difference in depth of focus is small enough to be ignored and does not cause problems such as image blur.

The incidence angle phi _in, as described above, and φ _in = 0.
In this case, as shown in FIG. 17, it is possible to obtain the same light distribution characteristic even if the cylindrical lens 5a is divided into a Fresnel lens shape.
Even in the case of φ _in ≠ 0, if the cylindrical lens 5a is divided _in parallel with the incident angle φ _in , the same light distribution characteristic can be obtained even in the shape of the Fresnel lens.
Further, even if the divided cylindrical lenses 5a are rearranged as shown in FIG. 18, the light distribution characteristics do not change unless the emitted light beam interferes with the divided lenses.

Embodiment 3 FIG.
Although not particularly mentioned in the first embodiment, an antireflection layer for reducing reflection may be formed on the light exit surface of the diffusion sheet 6 in order to reduce the influence of external light.
Further, an anti-glare layer may be formed on the light exit surface of the diffusion sheet 6 to prevent glare from appearing, and an anti-static layer may be used to prevent adhesion of dust due to static electricity.
Further, a hard coat layer may be formed on the light exit surface of the diffusion sheet 6 in order to protect the surface.

Embodiment 4 FIG.
As shown in FIGS. 1 and 15, the transmissive screen 2 is collimated by the Fresnel prism 3 a of the Fresnel optical element 3 that bends the light beam emitted from the projector 1 toward the observer side, and the light beam is applied to the cylindrical lens sheet 5. Incident.
Therefore, the incidence angle phi _in the light flux to cylindrical lens sheet 5 becomes approximately zero degrees.

A general Fresnel lens often uses a refraction in which a prism portion is formed on a light exit surface (surface on the base 4 side).
In the case of oblique projection in which the incident angle from the projector 1 to the Fresnel lens exceeds about 40 degrees, the light exit surface refraction type Fresnel lens as described above cannot collimate the light beam toward the cylindrical lens sheet 5. .
In such oblique projection, the Fresnel optical element 3 having the Fresnel prism 3a formed on the light incident surface is used.
Specifically, the following Fresnel optical elements 3 (1) to (4) are used.

(1) A plurality of Fresnel prisms 3a (total reflection prisms) having a refracting surface that refracts the light beam emitted from the projector 1 and a reflecting surface that reflects the light beam refracted by the refracting surface are arranged in a sawtooth shape. Fresnel optical element 3 (see FIGS. 19 and 23)
(2) A Fresnel prism 3a (total reflection prism) having a refracting surface that refracts light rays emitted from the projector 1 and a reflecting surface that reflects light rays refracted by the refractive surface; Fresnel optical element 3 (see FIGS. 20 and 24) in which a plurality of mixed Fresnel prisms (hybrid prisms) having a refractive surface that refracts the light is formed in one pitch. reference)
(3) In the Fresnel optical element 3 in which a plurality of Fresnel prisms 3a having a refracting surface that refracts a light beam irradiated from the projector 1 and a reflecting surface that reflects a light beam refracted by the refracting surface are arranged in a sawtooth shape. The non-incident surface that is blocked by the front Fresnel prism 3a (lower Fresnel prism 3a in the figure) and is not directly irradiated with light from the projector 1 is formed substantially parallel to the surface of the base 4 ( Fresnel optical element 3 in which a plurality of partial reflection prisms are arranged (see FIGS. 21 and 25)
(4) In the Fresnel optical element 3 in which a plurality of Fresnel prisms 3a having a refracting surface that refracts a light beam irradiated from the projector 1 and a reflecting surface that reflects a light beam refracted by the refracting surface are arranged in a sawtooth shape. The Fresnel optical element 3 (a plurality of Fresnel prisms 3a (partial total reflection prisms) in which a part of the prism front end portion formed by the refractive surface and the reflection surface is substantially parallel to the light beam irradiated from the projector 1 is disposed. (See FIGS. 22 and 26)

When the above-described Fresnel optical element 3 is used, the direction of light is changed using a total reflection phenomenon inside the prism, unlike a conventional light exit surface refraction type Fresnel lens. The reflection of light has the same incident angle and outgoing angle from Snell's law.
When viewed from the incident light, the outgoing light is bent about twice the angle δ between the surface and the incident light, as shown in FIG.
Further, since the refractive index inside the prism is larger than 1, when the refractive index inside the prism is n, it is bent about 2n times when viewed from the outside of the prism (refractive index is 1). . For example, when the refractive index inside the prism is 1.5, it is bent about 3 times when viewed from the outside of the prism.

As described above, since the Fresnel optical element 3 using the total reflection phenomenon greatly bends the light beam, the light beam can be bent toward the cylindrical lens sheet 5 even when the incident angle from the projector 1 to the Fresnel optical element 3 is large. However, on the other hand, when the inclination of the total reflection surface is slightly deviated from the design value, the angle deviation is also enlarged by 2n times.
For example, when the reflecting surface of the Fresnel prism 3a in FIG. 19 is inclined by Δ from the design value, the light emitted from the projector 1 is bent in a direction shifted by 2Δ from the normal direction, and is viewed from the outside of the prism. Are observed with a deviation of about 2n ₁ / n ₀ Δ (the light rays are also refracted on the plane DO in FIG. 19). Here, n ₁ is the refractive index inside the Fresnel prism 3a, and n ₀ is the refractive index outside the Fresnel prism 3a.
The same description can be made with reference to FIGS.

Therefore, in the case of large oblique projection in which the incident angle from the projector 1 to the Fresnel optical element 3 exceeds about 40 degrees, the center of the concentric circle of the Fresnel optical element 3 arranged concentrically is arranged outside the screen. To do.
For example, as shown in FIG. 23, the transmissive screen is a horizontally long rectangle, so that horizontally long prism arcs are arranged in parallel in the vertical direction.
In the Fresnel optical element 3 utilizing the total reflection phenomenon, the light beam is bent toward the cylindrical lens sheet 5 by the Fresnel prism 3a which is a total reflection prism. In the original case where there is no angle shift, the light beam is bent in the normal direction (see solid arrow), but if there is an angle shift, the light beam is bent in the shifted direction (see dotted arrow). The enlarged angular deviation is in the vertical direction.
The same description can be made with reference to FIGS.

On the other hand, when the viewing angle has a wide characteristic (wide light distribution characteristic), there is another new effect that the angle deviation of the light beam is made by the light distribution characteristic and the angle deviation of the light beam becomes inconspicuous.
FIG. 47 is an explanatory view schematically showing an example in the case where the light distribution characteristic by the cylindrical lens sheet 5 is narrow, and FIG. 48 is an explanatory view schematically showing an example in the case where the light distribution characteristic by the cylindrical lens sheet 5 is wide. It is.
When the light distribution characteristic is narrow, as shown in FIG. 47, the light beam separated into the light beam with the normal angle and the light beam with the shifted angle is not sufficiently mixed due to the narrow light distribution. Observed.
On the other hand, when the light distribution characteristic is wide, as shown in FIG. 48, the light beams separated into the regular angle light beam and the shifted light beam are sufficiently mixed for wide light distribution. Will not be observed, and no deviation of light will be observed.

In other words, by combining the Fresnel optical element 3 and the cylindrical lens sheet 5 using the total reflection phenomenon, the light distribution characteristic (brightness unevenness) can be reduced, as well as the light distribution characteristics can be easily widened for easy viewing. Play.
In addition, in the conventional case, a light incident surface refracting type Fresnel lens in which a prism having a refracting action is formed on a light incident surface and a light emitting surface refractive type Fresnel lens in which a prism is formed on a light emitting surface are totally reflected. Since the light does not bend significantly and the deviation from the design value is not enlarged, the angle deviation is not detected even if the viewing angle is narrow, so that there is no problem.

Embodiment 5. FIG.
The transmissive screen on which the Fresnel optical element 3 utilizing the total reflection phenomenon is arranged may be applied to oblique projection in which the incident angle from the projector 1 to the Fresnel optical element 3 exceeds about 40 degrees as described above. Many.
In such an extremely oblique projection, the influence on the light beam due to the bending or distortion of the substrate 4 holding the Fresnel optical element 3 is larger than that of a normal light exit surface refraction type Fresnel lens.
For example, when the incident angle from the projector 1 is Φ and the thickness of the base 4 is t, the height position of the light beam is represented by t · tan Φ.

However, the normal pitch of the Fresnel prism 3a in the Fresnel optical element 3 is about 0.1 mm, and the height (thickness direction) of the triangular Fresnel prism 3a is almost the same.
On the other hand, the thickness of the base 4 is about 1.0 to 5.0 mm, which is 10 times or more thicker than the Fresnel prism 3a (in FIGS. 19 to 22, the thickness t of the base 4 is shown compressed). .
Here, since h _v << t, the thickness of the Fresnel prism 3a (for example, h _v in FIG. 21) is ignored, but is actually proportional to the sum of the thickness of the Fresnel prism 3a and the thickness of the base 4. Needless to say.
In practice, the Fresnel optical element 3 and the substrate 4 may be paired. For example, the substrate 4 is pressed against a mold in which the shape of the Fresnel prism 3a is engraved, and is extruded to copy the shape of the Fresnel prism 3a on the substrate 4, or the film-like Fresnel prism 3a is bonded to the substrate 4 You may paste together (not shown).

When the deflection of the substrate 4 is Δt and the deflection Δt is approximated to the parallel movement of the position of the Fresnel prism 3a, it is expressed by (t + Δt) tanΦ.
Φ = 45 degrees and tanΦ = 1. However, when the incident angle Φ exceeds 45 degrees, tanΦ suddenly increases.
For example, Φ = 70 degrees and tanΦ = 2.74, which means that the height position is shifted by about 3 times with respect to the deflection Δt.
For the sake of simplification, it has been considered that the base plate 4 is simply moved in parallel for the sake of simplification. However, in actuality, the angle also changes, and it goes without saying that this naturally causes the aforementioned angle deviation.
From the above, in the case of a transmissive screen in which the Fresnel optical element 3 utilizing the total reflection phenomenon is arranged, when using a glass with high flatness (less bending) as the base 4 for holding the Fresnel optical element 3, Due to the action of both the base 4 and the cylindrical lens sheet 5, an effect of reducing the angle deviation can be obtained.

Embodiment 6 FIG.
In the first to fifth embodiments described above, the diffusion sheet 6 diffuses the light beam emitted from the light exit surface of the cylindrical lens sheet 5, but as shown in FIG. 28, the cylindrical lens 8a is horizontal on the light entrance surface. The lenticular sheet 8 is connected to the direction and spreads the light beam emitted from the light exit surface of the cylindrical lens sheet 5. The lenticular sheet is disposed on the non-light-collecting portion (black region in the drawing) of the light exit surface of the lenticular sheet 8. A striped light absorbing member 9 that absorbs light other than the light emitted from the light exit surface of the sheet 8 may be disposed between the cylindrical lens sheet 5 and the diffusion sheet 6.
However, the conditions regarding the shape of the cylindrical lens 5a in the cylindrical lens sheet 5 are the same as those in the first embodiment.
That is, the shape of the cylindrical lens 5a is represented by a curve that satisfies the conditions of 0.106 <d / p <0.135 and 35.8 degrees <θ _max <36.9 degrees.

Further, the cylindrical lens 5a is not limited to a convex lens as described above, and may be a concave lens as shown in FIG. Further, as shown in FIG. 30, a Fresnel-shaped lens may be used.
In the examples of FIGS. 28 to 30, the Fresnel prism 3a is the hybrid prism of (2). However, the invention is not limited to this, and the Fresnel prism 3a is a total reflection prism (1) (see FIG. 28). 31), (3) partial total reflection prism (see FIG. 32), and (4) partial total reflection prism (see FIG. 33).

Embodiment 7 FIG.
In the sixth embodiment, the case where the lenticular sheet 8 and the light absorbing member 9 are disposed between the cylindrical lens sheet 5 and the diffusion sheet 6 is shown. However, as shown in FIG. A lenticular sheet 10 in which a trapezoidal unit lens 10a for emitting a part of the light beam emitted from the light exit surface is connected in the horizontal direction and the valley of the unit lens 10a in the lenticular sheet 10 The striped light absorbing member 11 is disposed in a portion (black region in the figure) and absorbs light other than the light emitted from the unit lens 10a of the lenticular sheet 10. The cylindrical lens sheet 5 and the diffusion sheet 6 You may make it arrange | position between.
However, the conditions regarding the shape of the cylindrical lens 5a in the cylindrical lens sheet 5 are the same as those in the first embodiment.
That is, the shape of the cylindrical lens 5a is represented by a curve that satisfies the conditions of 0.106 <d / p <0.135 and 35.8 degrees <θ _max <36.9 degrees.

Further, the cylindrical lens 5a is not limited to a convex lens as described above, and may be a concave lens as shown in FIG. Further, as shown in FIG. 36, a Fresnel-shaped lens may be used.
In the examples of FIGS. 34 to 36, the Fresnel prism 3a is the hybrid prism of (2). However, the present invention is not limited to this, and the Fresnel prism 3a is a total reflection prism (1) (see FIG. 34). 37), (3) partial total reflection prism (see FIG. 38), and (4) partial total reflection prism (see FIG. 39).

Embodiment 8 FIG.
In the seventh embodiment, the lenticular sheet 10 and the light absorbing member 11 are disposed between the cylindrical lens sheet 5 and the diffusion sheet 6. However, as shown in FIGS. 5, the order of the lenticular sheet 10 and the light absorbing member 11 may be changed, and the lenticular sheet 10 and the light absorbing member 11 may be arranged on the incident side of the cylindrical lens sheet 5.
However, the conditions regarding the shape of the cylindrical lens 5a in the cylindrical lens sheet 5 are the same as those in the first embodiment.
That is, the shape of the cylindrical lens 5a is represented by a curve that satisfies the conditions of 0.106 <d / p <0.135 and 35.8 degrees <θ _max <36.9 degrees.

  Although not particularly mentioned in the above embodiment, a housing, a holding mechanism, an air conditioner, a speaker, a TV stand, a remote control light receiving unit, an electric circuit, a geometric correction circuit, a color correction circuit, and the like are provided as a projection display device. You may add as a component of.

It is a block diagram which shows the projection type display apparatus by Embodiment 1 of this invention. It is a perspective view which shows a part of transmissive screen by Embodiment 1 of this invention. It is a schematic diagram which shows the cylindrical lens of a cylindrical lens sheet. It is a schematic diagram which shows a cylindrical lens in case a radius is small. It is a schematic diagram which shows a cylindrical lens in case a lens pitch is small. It is explanatory drawing which shows the refraction phenomenon of a light ray. It is explanatory drawing which shows the light distribution characteristic in case a cylindrical lens is a convex lens. It is explanatory drawing which shows the angle dependence of the screen gain by a lens single-piece | unit. It is explanatory drawing which shows the angle dependence of the screen gain by a lens single-piece | unit. It is explanatory drawing which shows the angle dependence of the screen gain by a lens single-piece | unit. It is explanatory drawing which shows the example of viewing angle (alpha) and (gamma). It is explanatory drawing which shows the comprehensive screen gain in consideration of the light distribution characteristic of both a cylindrical lens and a diffusion sheet. It is explanatory drawing which shows the comprehensive screen gain in consideration of the light distribution characteristic of both a cylindrical lens and a diffusion sheet. It is explanatory drawing which shows the comprehensive screen gain in consideration of the light distribution characteristic of both a cylindrical lens and a diffusion sheet. It is a block diagram which shows the other projection type display apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the light distribution characteristic in case a cylindrical lens is a concave lens. It is explanatory drawing which shows the light distribution characteristic in case a cylindrical lens is a Fresnel lens shape. It is explanatory drawing which shows the light distribution characteristic in case a cylindrical lens is a Fresnel lens shape. It is explanatory drawing which shows the shape of a Fresnel optical element, and the optical path of a light ray. It is explanatory drawing which shows the shape of a Fresnel optical element, and the optical path of a light ray. It is explanatory drawing which shows the shape of a Fresnel optical element, and the optical path of a light ray. It is explanatory drawing which shows the shape of a Fresnel optical element, and the optical path of a light ray. It is a perspective view which shows the transmission type screen by Embodiment 4 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 4 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 4 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 4 of this invention. It is explanatory drawing which shows the relationship between an incident light ray and an emitted light ray. It is a perspective view which shows the transmission type screen by Embodiment 6 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 6 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 6 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 6 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 6 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 6 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 7 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 7 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 7 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 7 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 7 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 7 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 8 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 8 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 8 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 8 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 8 of this invention. It is a perspective view which shows the transmission type screen by Embodiment 8 of this invention. It is explanatory drawing which shows the calculation result of a light distribution characteristic. It is explanatory drawing which shows the brightness | luminance of a light ray when the light distribution characteristic by a cylindrical lens sheet is narrow. It is explanatory drawing which shows the brightness | luminance of a light ray in case the light distribution characteristic by a cylindrical lens sheet is wide.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Projector (light-emitting body), 1a Projection optical system, 1b Light valve, 1c Illumination optical system, 2 Transmission type screen, 3 Fresnel optical element, 3a Fresnel prism, 4 Base, 5 Cylindrical lens sheet, 5a Cylindrical lens, 6 Diffusion sheet , 7 Reflector, 8 Lenticular sheet, 8a Cylindrical lens, 9 Light absorbing member, 10 Lenticular sheet, 10a Unit lens, 11 Light absorbing member.

Claims (23)

  A transmission type comprising a cylindrical lens connected in the vertical direction on the light exit surface, a cylindrical lens sheet that spreads the light emitted from the light emitter, and a diffusion sheet that diffuses the light emitted from the light exit surface of the cylindrical lens sheet screen.   A prism is formed on the light entrance surface, and a Fresnel optical element that deflects the light beam emitted from the light emitter and a cylindrical lens connected in the vertical direction on the light output surface, and the light beam emitted from the light exit surface of the Fresnel optical element A transmission type screen comprising: a cylindrical lens sheet that is spread; and a diffusion sheet that diffuses light emitted from a light exit surface of the cylindrical lens sheet.   A prism is formed on the light entrance surface, and a Fresnel optical element that deflects the light beam emitted from the light emitter and a cylindrical lens connected in the vertical direction on the light output surface, and the light beam emitted from the light exit surface of the Fresnel optical element A cylindrical lens sheet that spreads, a cylindrical lens connected in a horizontal direction on the light incident surface, a lenticular sheet that spreads the light emitted from the light exit surface of the cylindrical lens sheet, and a non-condensing part on the light exit surface of the lenticular sheet A transmission type screen comprising: a light absorbing member that is disposed and absorbs light other than light emitted from the light exit surface of the lenticular sheet; and a diffusion sheet that diffuses light emitted from the light exit surface of the lenticular sheet.   A prism is formed on the light entrance surface, and a Fresnel optical element that deflects the light beam emitted from the light emitter and a cylindrical lens connected in the vertical direction on the light output surface, and the light beam emitted from the light exit surface of the Fresnel optical element A cylindrical lens sheet that spreads, and a lenticular sheet in which a trapezoidal unit lens that emits the light beam after being partially reflected from the light exit surface of the cylindrical lens sheet is connected in the horizontal direction; A light-absorbing member that is disposed in a valley of the unit lens in the lenticular sheet and absorbs light other than light emitted from the unit lens of the lenticular sheet, and diffusion that diffuses light emitted from the unit lens of the lenticular sheet A transmissive screen with a sheet.   A prism is formed on the light incident surface to deflect the light emitted from the light emitter, and a part of the light emitted from the light exit surface of the Fresnel optical element is totally reflected, and then the light is emitted. A lenticular sheet in which trapezoidal unit lenses to be connected are formed in a horizontal direction, and light absorption that absorbs light other than light emitted from the unit lens of the lenticular sheet, and is disposed in the valley of the unit lens in the lenticular sheet A cylindrical lens sheet that vertically connects a cylindrical lens on the light-exiting surface, spreads the light emitted from the unit lens of the lenticular sheet, and the diffusion that diffuses the light emitted from the light-exiting surface of the cylindrical lens sheet A transmissive screen with a sheet.   The transmissive screen according to any one of claims 1 to 5, wherein the cylindrical lens formed on the light exit surface of the cylindrical lens sheet is a convex lens.   The transmissive screen according to claim 1, wherein the cylindrical lens formed on the light exit surface of the cylindrical lens sheet is a concave lens.   The transmissive screen according to any one of claims 1 to 5, wherein a diffusion sheet having a haze value in the range of 80% to 85% is used.   The at least one layer of an antireflection layer, an antistatic layer, and a hard-coat layer is formed in the light emission surface of a diffusion sheet, The any one of Claims 1-5 characterized by the above-mentioned. Transmission screen. When the thickness of the cylindrical lens formed on the light exit surface of the cylindrical lens sheet is d, the pitch of the cylindrical lens is p, and the maximum inclination of the cylindrical lens is θ _max , 0.106 <d / p <0.135 And the shape of the cylindrical lens is represented by a curve satisfying the condition of 35.8 degrees <θ _max <36.9 degrees. The transmission screen according to the item.   The transmissive screen according to any one of claims 2 to 5, wherein the Fresnel optical element is held on a glass substrate.   The transmissive screen according to any one of claims 2 to 5, wherein the Fresnel optical elements are arranged concentrically.   The transmissive screen according to any one of claims 2 to 5, wherein the center of the Fresnel optical element is formed outside the screen.   The transmissive screen according to any one of claims 2 to 5, wherein the pitch of the Fresnel optical element is finer than the pixels of the screen.   The Fresnel optical element has a structure in which a plurality of prisms having a refracting surface that refracts a light beam emitted from a light emitter and a reflecting surface that reflects a light beam refracted by the refracting surface are arranged in a sawtooth shape. The transmissive screen according to claim 2, wherein the transmissive screen is provided.   The Fresnel optical element has a refracting surface that refracts a light beam radiated from a light emitter, a reflection surface that reflects a light beam refracted by the refracting surface, and a light beam emitted from the light emitter. 6. The structure according to claim 2, wherein a plurality of prisms each having a refracting surface that refracts the light and having a refractive surface formed at one pitch are arranged in a sawtooth shape. The transmission screen according to the item.   16. The transmission screen according to claim 15, wherein a non-incident surface of the prism which is blocked by a front prism and is not directly irradiated with light from the light emitter is formed substantially parallel to the base surface.   16. The transmission screen according to claim 15, wherein a part of a prism front end portion formed by the refracting surface and the reflecting surface is missing substantially in parallel with the light beam emitted from the light emitter.   A light emitting body that irradiates light, a cylindrical lens connected in a vertical direction on the light exit surface, a cylindrical lens sheet that spreads the light emitted from the light emitter, and a light beam emitted from the light exit surface of the cylindrical lens sheet A projection display device comprising a diffusion sheet that is used.   A light emitting body that irradiates light, a prism is formed on the light incident surface, a Fresnel optical element that deflects the light emitted from the light emitting body, and a cylindrical lens that is connected to the light emitting surface in the vertical direction. A projection display device comprising: a cylindrical lens sheet that spreads the light beam emitted from the light exit surface; and a diffusion sheet that diffuses the light beam emitted from the light exit surface of the cylindrical lens sheet.   A light emitting body that irradiates light, a prism is formed on the light incident surface, a Fresnel optical element that deflects the light emitted from the light emitting body, and a cylindrical lens that is connected to the light emitting surface in the vertical direction. A cylindrical lens sheet that spreads the light beam emitted from the light exit surface, a lenticular sheet that extends the light beam emitted from the light exit surface of the cylindrical lens sheet, with a cylindrical lens connected in the horizontal direction on the light entrance surface, and the lenticular sheet A light-absorbing member that is disposed in the non-light-collecting portion of the light-exiting surface and absorbs light rays other than light rays emitted from the light-exiting surface of the lenticular sheet, and a diffusion sheet that diffuses light rays emitted from the light-exiting surface of the lenticular sheet And a projection display device.   A light emitting body that irradiates light, a prism is formed on the light incident surface, a Fresnel optical element that deflects the light emitted from the light emitting body, and a cylindrical lens that is connected to the light emitting surface in the vertical direction. A cylindrical lens sheet that spreads the light beam emitted from the light exit surface, and a trapezoidal unit lens that emits the light beam after partially reflecting a part of the light beam emitted from the light exit surface of the cylindrical lens sheet in the horizontal direction A lenticular sheet connected to the lenticular sheet, a light-absorbing member that is disposed in a valley of the unit lens in the lenticular sheet, and absorbs light other than light emitted from the unit lens of the lenticular sheet, and a unit lens of the lenticular sheet A projection display device comprising: a diffusion sheet that diffuses light emitted from the projector. A light-emitting body that irradiates light, a prism is formed on the light-incident surface, deflects the light emitted from the light-emitting body, and a part of the light emitted from the light-emitting surface of the Fresnel optical element. A lenticular sheet in which a trapezoidal unit lens that emits the light beam after being reflected is connected in the horizontal direction, and a valley of the unit lens in the lenticular sheet, and is emitted from the unit lens of the lenticular sheet A light-absorbing member that absorbs light other than light, a cylindrical lens connected to the light-emitting surface in the vertical direction, and spreads light emitted from the unit lens of the lenticular sheet; and a light-emitting surface of the cylindrical lens sheet A projection display device comprising: a diffusion sheet that diffuses light emitted from the projector.

Images