JP2012181222A - Method of manufacturing columnar lens sheet for displaying stereoscopic image - Google Patents

Abstract

Provided is a method for manufacturing a columnar lens sheet for stereoscopic image display, in which, when a lenticular lens is used for autostereoscopic viewing, the size of the lens changes with time and crosstalk between left and right parallax images is improved. .
A columnar lens sheet for stereoscopic image display includes a columnar lens group in which unit columnar lenses are arranged on a base film 1 that is a continuous belt-like stretched film, and unit columnar lenses as columnar lens patterns 31 on a mold surface. It is manufactured by molding as a cured product of an ionizing radiation curable resin liquid with a rotating cylindrical molding die 30 having a large number of concave grooves 32 for molding. At this time, an inclination defined as an inferior angle of an angle formed by the orientation direction dm of the molecular principal axis of the resin constituting the base film and the extending direction dq of the concave groove 32 that becomes the ridge line direction of the unit columnar lens 2. Manufacture is performed such that the angle θ is 0 ° ≦ δ ≦ 50 ° over the entire area of the columnar lens pattern.
[Selection] Figure 3

Description

  The present invention manufactures a columnar lens sheet for stereoscopic image display having unit columnar lenses such as a lenticular lens, which is suitable for various stereoscopic image display device applications, particularly for autostereoscopic image display that does not require special glasses for stereoscopic vision. Regarding the method. In particular, the present invention relates to a method for manufacturing a stereoscopic image display lens sheet in which crosstalk between right and left parallax images due to a change in lens dimensions over time hardly occurs.

  In recent years, due to advances in technology such as high-definition display panels, stereoscopic image display for 3D televisions and the like that can display 3D images using flat panel displays such as liquid crystal panels that display 2D images Devices are spreading rapidly. As stereoscopic image display devices that are currently popular, glasses that require glasses are often used as a stereoscopic image display method, but autostereoscopic image display devices that do not require glasses and can be viewed with the naked eye have also been put into practical use. Yes. There is a lenticular system using a lenticular lens as one of the autostereoscopic systems that enables stereoscopic viewing with the naked eye, and various proposals have been made (Patent Documents 1 and 2).

JP-A-6-78342 Japanese Patent Laid-Open No. 10-232369

  By the way, from the viewpoint of cost, ease of manufacture, etc., the lenticular lens is preferably made of resin. Here, when the display panel is a liquid crystal panel (liquid crystal display element), when such a resin lenticular lens is combined with the liquid crystal panel, the arrangement period of the lenticular lens is Subtle dimensional changes due to heat over time. On the other hand, since the front and back substrates are made of glass, the liquid crystal panel has less dimensional change than the resin. For this reason, the relative positions of the pixels of the liquid crystal panel and the arrangement direction of the lenticular lenses (direction orthogonal to the ridge line direction) are shifted with time. However, in order to display a stereoscopic image, the lenticular lens needs to be maintained in a highly accurate positional relationship with the pixels of the liquid crystal panel.

And if the relative positional relationship between the pixels of the liquid crystal panel and the lenticular lens is distorted, the accuracy of sorting the left image and right image displayed on the liquid crystal panel to the left and right eyes by the lenticular lens decreases, and the left and right parallax images So-called crosstalk occurs in which three-dimensional images are deteriorated.
The problem of crosstalk between left and right parallax images is also caused by the movement of the observation position of an image observer (hereinafter also simply referred to as an observer). For this reason, various improvements have been proposed. This is based on the premise that the relative positional relationship with the pixel is correctly maintained, and is not a measure for maintaining the relative positional relationship between the lens and the pixel.

  That is, the problem of the present invention is that when a unit columnar lens such as a lenticular lens is used for autostereoscopic viewing, the dimensional change of the unit columnar lens over time, particularly the dimensional change of the unit columnar lens in the arrangement direction. It is to provide a method for manufacturing a columnar lens sheet for stereoscopic image display in which crosstalk between left and right parallax images is improved with time.

The present invention provides a method for manufacturing a columnar lens sheet for stereoscopic image display having the following configuration.
On one surface of the base film made of stretched film, the unit columnar lens has a columnar lens group in which ridge lines are arranged in one direction in parallel to each other, and the orientation direction of the molecular principal axis of the resin constituting the base film And the ridge line direction of the unit columnar lens, the inclination angle θ defined as a subordinate angle among the angles formed in a plane parallel to one surface of the base film is 0 ° throughout the base film. ≦ θ ≦ 50 °, a method for manufacturing a columnar lens sheet for stereoscopic image display,
On the mold surface as a mold, the unit columnar lens molding surface having an irregular shape opposite to that of the unit columnar lens is arranged, and a rotating cylindrical molding die having a columnar lens pattern having an irregular shape opposite to the columnar lens group is provided. The substrate film made of a continuous belt-like stretched film is supplied via an ionizing radiation curable resin liquid, and is superposed on the mold surface of the mold so that the columnar lens pattern is filled with the resin liquid. Then, the columnar lens group formed in close contact with one surface of the base film by irradiating ionizing radiation to cure the resin liquid and then releasing the base film When manufacturing the columnar lens sheet for stereoscopic image display consisting of:
On the mold surface, the orientation direction of the molecular principal axis of the resin constituting the continuous belt-shaped base film, and the ridge line direction on the unit columnar lens molding surface having a concave-convex shape opposite to the unit columnar lens of the cylindrical mold The columnar lens sheet for stereoscopic image display is manufactured by setting the inferior inclination angle θ formed by 0 ° ≦ θ ≦ 50 ° over the entire area of the columnar lens pattern on the mold surface.

  According to the manufacturing method of the present invention, the dimensional change with time of the arrangement period of the unit columnar lenses can be reduced, and the crosstalk of the left and right parallax images can be prevented from occurring with time due to the change with time particularly in the heating environment. A columnar lens sheet for stereoscopic image display can be easily manufactured.

The perspective view (a) and top view (b) explaining an example of the columnar lens sheet for stereoscopic image display obtained with the manufacturing method by this invention. The perspective view explaining an example of the optical member for stereoscopic image display using the columnar lens sheet for stereoscopic image display by this invention. Explanatory drawing explaining the manufacturing method of the columnar lens sheet for stereoscopic image display by this invention. The top view explaining the orientation angle (gamma) of the subordinate angle of the flow direction MD and the orientation direction dm of a molecular principal axis in a continuous strip-shaped base film. The top view explaining distribution of the orientation direction dm of the molecular principal axis in the width direction TD in the continuous strip-shaped base film. The top view explaining the relationship between the flow direction MD and the width direction TD in a continuous strip-shaped base film, and the longitudinal direction dx in a sheet | seat sheet.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are conceptual diagrams, and the scale relationships, aspect ratios, and the like of components may be exaggerated.
In order to facilitate understanding of the manufacturing method of the present invention, the description first explains what the columnar lens sheet for stereoscopic image display manufactured by this manufacturing method is, and then the manufacturing method of the present invention. Will be explained. Further, the material of the component will be described later.

[A] Columnar lens sheet for stereoscopic image display:
First, an example of a columnar lens sheet for stereoscopic image display that can be manufactured according to the present invention is shown in a perspective view of FIG. 1A and a plan view of FIG. The columnar lens sheet 10 for stereoscopic image display illustrated in FIG. 1 shows a state of a rectangular sheet cut out as a product after being manufactured as a continuous belt-like sheet.
In general, the size and shape of the base film 1 in plan view (XY plane) are equal to the size and shape of the columnar lens sheet 10 for stereoscopic image display.
When the columnar lens sheet 10 for stereoscopic image display is laminated with the glass substrate 5 like the optical member 20 for stereoscopic image display which will be described later with reference to FIG. 2, the size and shape of the base film 1 is glass. It is equal to or smaller than the size and shape of the substrate 5.

  In FIG. 1, the plane of the stereoscopic image display columnar lens sheet 10 (a plane parallel to one surface 1p of the base film 1 described later) is parallel to the XY plane, and the X-axis direction is observed in the stereoscopic image display. The horizontal direction in which the left and right parallax images viewed by the person S are distributed to the left and right, the Y-axis direction being the vertical direction or a direction orthogonal to the horizontal direction, and the direction of the normal n with respect to the XY plane of the columnar lens sheet 10 for stereoscopic image display Is the Z axis. This Z-axis direction is assumed to be the direction of the observer S of the stereoscopic image.

  In the columnar lens sheet 10 for stereoscopic image display shown in the figure, a large number of unit columnar lenses 2 are arranged on one surface 1p of the base film 1 and the ridgelines 2p are parallel to each other in one direction da (X-axis direction in the drawing). Has been. The arrangement period P of the unit columnar lenses 2 in the one direction da is constant. The arrangement period P is the distance between the ridge lines 2p of the adjacent unit columnar lenses 2. Alternatively, the arrangement period P can also be grasped as the distance between the adjacent valley portions 2v with respect to the valley portions 2v between the adjacent unit columnar lenses 2 (not shown). A plurality of unit columnar lenses 2 arranged periodically constitute a columnar lens group 3. The three-dimensional image display columnar lens sheet 10 includes the columnar lens group 3 and the base film 1.

(Orientation direction dm of molecular principal axis)
As for the orientation of the molecular principal axis, a stretched film such as a biaxially stretched film is used for the base film 1, and as a result, the direction of the molecular principal axis of the polymer constituting the base film 1 in the film plane is Oriented rather than disordered.
In the present invention, since the base film 1 to be used is a stretched film, the polymer constituting the film in the film plane, in other words, in the plane parallel to the one face 1p of the base film 1 is used. This is related to the fact that the molecular axis directions of the individual molecules are not completely random but are aligned to some extent. For this reason, if the direction of the molecular axis of each molecule, that is, the orientation direction, is averaged as a whole within an area that is sufficiently larger than the molecule and smaller than the pixels of the display panel to be applied, for example, in a 10 μm square area, Direction. The direction obtained by averaging the orientation directions of the molecular axes of the individual molecules as a whole is the orientation direction dm of the molecular principal axis. In FIG. 1B and FIG. 3, a double-headed arrow indicated by dm is the orientation direction of the molecular principal axis.
Note that even if the orientation direction dm of the molecular principal axis is aligned to some extent, normally, the alignment direction dm is not aligned in one direction over the entire surface, and the orientation direction dm of the molecular principal axis is shown in FIG. ) Is distributed as a function dm (X, Y) of position coordinates (X, Y) in the XY plane (a plane parallel to one surface 1p of the base film 1). That is, the orientation direction dm of the molecular principal axis is within a certain range (a range in which the inclination angle θ is 0 ° ≦ θ ≦ 50 °) depending on the location in the plane (parallel to one surface 1p) of the base film 1. Is different.

(Inclination angle θ)
And it is defined as the minor angle of the smaller one of the angles formed by the orientation direction dm of the molecular principal axis and the ridge line direction dp (Y-axis direction in the drawing) which is the direction in which the ridge line 2p of the unit columnar lens 2 extends. The tilt angle θ is also distributed as a function θ (X, Y) of position coordinates (X, Y) in the XY plane (a plane parallel to one surface 1p of the base film 1). Is set to fall within the range of 0 ° ≦ θ ≦ 50 °.

Incidentally, it is preferable that the base film 1 has at least a region where the inclination angle θ is 0 °.
The region where the inclination angle θ is 0 ° is ideally the entire region of the base film 1. Therefore, a film in which the orientation direction dm of the molecular principal axis is extremely uniform, such as a polarizing plate film, may be used as the base film. However, such a film is not practical in that it requires advanced manufacturing techniques and is extremely expensive. Therefore, in-plane distribution of the alignment direction dm due to the presence of a certain degree of non-uniformity in the alignment direction dm (X, Y) is allowed, and at least a region where the inclination angle θ is 0 ° is partially set. It is good to have it even in.

Further, it is effective that the region where the inclination angle θ is 0 ° is as close to the center in the arrangement direction da of the unit columnar lenses 2 as much as possible. Here, the vicinity of the center, as shown in FIG. 1B, is a distance L between both ends in the arrangement direction da of the unit columnar lenses 2 of the base film 1, and among the both ends in the width direction of the base film 1. This is a region where the distance measured from one end satisfies (L / 2) ± (L / 4).
When the base film 1 does not include a region where the tilt angle θ is 0 °, the value of the tilt angle θ is in the distribution range of the tilt angle θ in the vicinity of the center of the base film 1. The average value or a value close to it should be set.

  As described above, by setting the in-plane distribution of the inclination angle θ, the dimensional change (contraction) in the arrangement direction da of the unit columnar lenses 2 of the stereoscopic image display columnar lens sheet 10 over time is minimized. It is possible and preferable.

(Application to stereoscopic image display optical members)
The columnar lens sheet 10 for stereoscopic image display has other optical elements on the surface on which the columnar lens group 3 is not formed, the surface on which the columnar lens group 3 is formed, or both surfaces. Can be stacked.
For example, the three-dimensional image display columnar lens sheet 10 may be used as the three-dimensional image display optical member 20 illustrated in FIG. 2 by closely laminating the glass substrate 5 on the side where the columnar lens group 3 is not formed. it can.

The stereoscopic image display optical member 20 in FIG. 2 is a columnar lens group including a plurality of unit columnar lenses 2 in addition to a flat glass substrate 5 with respect to the stereoscopic image display columnar lens sheet 10 illustrated in FIG. 3 is laminated on the surface opposite to the one surface 1 p having 3, that is, on the other surface 1 q of the base film 1 through the adhesive layer 4.
The stereoscopic image display optical member 20 in FIG. 2 has the light beam control pattern 6 on the lower surface of the glass substrate 5 opposite to the surface in contact with the pressure-sensitive adhesive layer 4. The light beam control pattern 6 has a period corresponding to (associated with) the arrangement period P of the unit columnar lenses 2 in one direction da (X-axis direction) that is the arrangement direction of the unit columnar lenses 2. For example, in the case of a color liquid crystal panel, the light ray control pattern 6 corresponds to a light blocking pattern of a black matrix in a color filter formed on the front glass substrate. Further, the light ray control pattern 6 as the light shielding pattern shows an image adjacent to the left and right parallax images displayed on the image display element when the viewpoint position of the observer S is slightly shifted in the left and right direction (X-axis direction in the drawing). In other words, it also has a function of making it difficult for crosstalk between right and left parallax images to occur.

  Note that in the case of a stereoscopic image display apparatus in which only the front side is an observable range for stereoscopic viewing, that is, in the case of two-lens display, in the lenticular method, one arrangement period P of unit columnar lenses 2 (in other words, one unit columnar lens 2) Corresponding to the above, two images of the left-eye image and the right-eye image are sufficient for the parallax image of the two-dimensional image displayed by the image display element. For this reason, in the case of binocular display, if the two images are alternately displayed in the direction of the arrangement period P, stereoscopic viewing is possible. Therefore, when a light-shielding pattern is provided between the left and right parallax images as the light beam control pattern 6, the period of the light-shielding pattern in the one direction da is a period in which the fineness of the arrangement period P of the unit columnar lenses 2 is twice. .

  With the configuration as described above, the columnar lens sheet for stereoscopic image display 10 used has an inclination angle θ formed by the ridge line direction dp of the unit columnar lens 2 and the molecular principal axis dm of the base film 1, and heat In the presence of the above, the dimensional change in the arrangement direction da of the unit columnar lenses 2 over time is minimized, and dimensional stability that prevents crosstalk of the left and right parallax images from occurring over time is obtained. When the light beam control pattern 6 is a light shielding pattern, it can be prevented from appearing with time in the presence of heat or the like. As a result, it is possible to prevent a decrease in luminance due to the appearance of the light shielding pattern.

As an application example of the stereoscopic image display columnar lens sheet 10, in the stereoscopic image display optical member 20 illustrated in FIG. 2, the stereoscopic image display columnar lens sheet 10 has a lens surface on the columnar lens group 3 side. It arrange | positioned toward the observer S side. However, although not illustrated, conversely, the base film 1 side, that is, the other surface 1q side can be arranged toward the observer S side.
In addition, the stereoscopic image display columnar lens sheet 10 may be disposed between the light source and the display panel on the light source side on the back surface of the display panel. In this case, the orientation of the lens surface of the columnar lens group 3 can be either on the display panel side (observer S side) or on the light source side.

[B] Method for producing columnar lens sheet for stereoscopic image display:
The manufacturing method of the columnar lens sheet for stereoscopic image display according to the present invention is a method capable of manufacturing the columnar lens sheet for stereoscopic image display 10 described above. Hereinafter, a description will be given with reference to FIG.

[Base film]
The base film 1 made of a stretched film is manufactured using a continuous strip film. The orientation direction dm of the molecular principal axis of the resin constituting the base film 1 is drawn as being parallel or substantially parallel to the flow direction MD of the continuous belt-like base film 1 in the figure. A flow direction MD (Machine Direction) is a direction in which the continuous belt-like base film 1 travels during manufacturing. A direction orthogonal to the flow direction MD is a width direction TD (Transverse Direction).

[Molding mold]
A cylindrical mold is used as the mold 30. The mold 30 has a columnar lens pattern 31 having a concave and convex shape opposite to the columnar lens group 3 in which the unit columnar lenses 2 are arranged in one direction with the ridgelines 2p parallel to each other on the mold surface. The columnar lens pattern 31 has a large number of unit columnar lens molding surfaces 32 that are concave and convex as opposed to the unit columnar lens 2 as concave grooves. The ridge line direction of the unit columnar lens molding surface 32 made of this concave groove is always the same as the ridge line direction dp of the unit columnar lens 2 obtained by molding.

(Ridge direction)
The ridge line direction dp of the unit columnar lens molding surface 32 composed of the concave grooves is parallel to or in the circumferential direction of the cylindrical molding die 30 (direction parallel to the rotation direction of the cylindrical molding die 30). It is drawn as almost parallel. The ridge line direction dp is the same direction as the ridge line direction dp of the unit columnar lens 2 after molding.
Note that the ridge line direction dp of the unit columnar lens molding surface 32 formed of a concave groove can be intentionally formed obliquely with respect to the circumferential direction of the cylindrical molding die 30.

(Inclination angle θ)
The inclination angle θ is determined by the orientation direction dm of the molecular main axis on the continuous belt-like substrate film 1 on the mold 30 and the unit columnar lens molding surface 32 formed by the concave grooves on the cylindrical mold 30. The ridge line direction dp is an inferior angle of angles formed in a plane parallel to the circumferential surface that is the mold surface in a state where the base film 1 is superimposed on the mold surface of the mold 30.
In the present invention, a stereoscopic image display is performed by combining the base film 1 and the mold 30 such that the inclination angle θ is 0 ° ≦ θ ≦ 50 ° over the entire area of the columnar lens pattern 31 on the mold surface. The columnar lens sheet 10 is manufactured.

(The meaning of the ridge line and the inclination angle θ on the mold surface)
Strictly speaking, the “ridge line” is a line of a convex portion formed by a ridge in a mountain. On the other hand, since the unit columnar lens molding surface 32 made of a concave groove has a concave and convex shape opposite to that of the unit columnar lens 2, the portion corresponding to the ridge line 2p in the unit columnar lens 2 corresponds to the line formed by the concave portion formed by the valley bottom. To do. However, since the ridge line 2p in the unit columnar lens 2 and the line formed by the valley bottom of the unit columnar lens molding surface 32 formed of the concave groove in the molding die are always in the same direction, in the present specification, these lines are referred to as Both are called “ridge lines” without distinction.
However, with respect to the “unit columnar lens 2”, a concave groove having a reverse uneven shape on the mold 30 for molding it is referred to as “unit columnar lens molding surface 32”.
For this reason, the “inclination angle θ” is originally an inferior angle formed by the orientation direction dm of the molecular main axis and the ridge line direction dp of the “unit columnar lens 2”. The minor angle B formed by the direction dm and the ridge line direction dp of the “unit columnar lens molding surface 32” of the mold 30 (strictly, the direction of the line formed by the valley bottom of the concave groove as described above) is always the minor angle A. (For example, this is not distinguished and referred to as “deviation angle δ”), and the minor angle A and the minor angle B are also called the “tilt angle θ” using the same “θ”. To.

[Orientation angle γ]
Here, as shown in the plan view of FIG. 4, the orientation angle γ is composed of the orientation direction dm of the molecular main axis on the continuous band-shaped base film 1 and the flow direction MD of the continuous band-shaped base film 1. It is defined as an inferior angle.
On the other hand, when the ridge line direction dp of the unit columnar lens molding surface 32 formed of a concave groove is parallel to the circumferential direction of the cylindrical molding die 30, the flow direction MD is always the circumferential direction of the molding die 30. Since it is parallel, the ridge line direction dp of the unit columnar lens molding surface 32 is parallel to the flow direction MD of the continuous strip-shaped base film 1.
In the production under the condition in which the ridge line direction dp and the flow direction MD are parallel, the inclination angle θ formed by the orientation direction dm of the molecular principal axis and the ridge line direction dp is equal to the orientation direction dm of the molecular principal axis. It is equal to the orientation angle γ formed by the flow direction MD of the material film 1.

  Therefore, a resin film having an orientation angle γ of 0 ° ≦ γ ≦ 50 ° over the entire width of the columnar lens pattern 31 on the mold surface of the mold 30 and over the entire length in the flow direction MD is used as the continuous belt-shaped base film 1. When the ridge line direction dp of the unit columnar lens molding surface 32 made of the concave groove is used and is manufactured by using the molding die 30 parallel to the circumferential direction, the orientation direction dm of the molecular main axis and the ridgeline of the unit columnar lens 2 are used. The columnar lens sheet 10 for stereoscopic image display in which the inclination angle θ formed by the direction dp is 0 ° ≦ θ ≦ 50 ° in the entire region of the base film 1 is manufactured.

[From substrate film supply and resin liquid curing to mold release]
Except for the inclination angle θ described above, the base film 1 is supplied to the mold 30 so that the ionizing radiation curable resin liquid is interposed therebetween, and the resin liquid is cured, so that the unit columnar lens 2 is formed. Forming a large number of arranged columnar lens groups 3 on one surface 1p of the base film 1 is the same as the conventionally known 2P method (photo-polymer method).

That is, the continuous belt-like base film 1 is supplied to the rotating mold 30 via the ionizing radiation curable resin liquid between the base film 1 and the mold surface, which is the circumferential surface of the mold 30, The film 1 is overlapped while running. The base film 1 is usually superimposed on the mold 30 by passing the base film 1 between a nip roller (not shown) and the mold 30.
The ionizing radiation curable resin liquid is applied to the mold surface of the mold 30, the surface of the base film 1, or both surfaces, and the base film 1 is supplied to the mold 30. As a result, the base film 1 is superimposed on the mold 30 with the resin liquid interposed therebetween, and the resin liquid is filled in the columnar lens pattern 31 on the mold surface of the mold 30. In this state, the resin liquid is cured by irradiating with ionizing radiation. Since a metal mold is usually used for the mold 30, irradiation is performed through the base film 1. As the ionizing radiation, ultraviolet rays are usually used, but other rays such as an electron beam and a visible ray may be used. In addition, if an ultraviolet transmissive material such as quartz is used for the mold 30, irradiation may be performed from the inside of the hollow mold 30.

(Mold temperature control)
In many cases, the temperature of the mold 30 rises due to the reaction heat of the curing reaction of the ionizing radiation curable resin liquid on the mold surface. If the surface temperature of the mold 30 (the temperature of the mold surface) is too high, the columnar lens sheet for stereoscopic image display is caused by the temperature difference from the columnar lens sheet for stereoscopic image display 10 that has been cooled to room temperature after mold release and its temperature history. 10 dimensional stability is reduced.
For this reason, it is preferable to control the mold surface of the mold 30 at the time of molding to a surface temperature as constant as possible within a range of 23 to 60 ° C. The temperature control can be performed by circulating a cooling medium such as water inside the mold 30. If the surface temperature is less than 23 ° C., the mold 30 is likely to condense, and if it exceeds 60 ° C., it becomes difficult to fit the intended dimensions when finished.
Thus, it is preferable to control the mold 30 to an appropriate temperature range, but in this respect, as ionizing radiation, the electron beam is less heat rays from the irradiation source than the ultraviolet ray, and the temperature rise due to the irradiation source. Is preferable.

(Preliminary dimension adjustment of columnar lens pattern)
The columnar lens pattern 31 on the mold surface of the mold 30 is formed on the mold surface due to a temperature difference from room temperature (23 ° C.) when the surface temperature of the mold surface of the mold 30 exceeds room temperature. In consideration of the expansion and contraction of the finished pattern with respect to the pattern, it is preferable to perform expansion and contraction (stretching) in advance so that the finished pattern has a desired dimension.
Therefore, the relationship of Pm, Ps, and Tm that satisfies the following formula [1] is adopted. here,
Pm is an arrangement period [μm] of the unit columnar lens molding surface 32 corresponding to the unit columnar lens 2 in the columnar lens pattern 31 on the mold surface.
P is an arrangement period [μm] of the unit columnar lenses 2 in the columnar lens group 3 in the columnar lens sheet 10 for stereoscopic image display.
Tm is the surface temperature [° C.] of the mold surface of the mold 30.
In Formula 1, 1.5 and 0.5 are intensity factors.

According to Formula 1, as the surface temperature Tm of the mold 30 increases from room temperature, the dimension on the mold surface (arrangement period Pm) is set smaller than the target finished dimension. At this time, by setting the dimensions within the range of the inequality of Expression 1, a more accurate finished dimension can be obtained.
For example, if the mold 30 is manufactured under conditions where the surface temperature Tm of the mold 30 is 53 ° C.,
Since the temperature difference from the room temperature of 23 ° C. is 30 ° C., the columnar shape of the arrangement cycle Pm having a size in the range of 0.99928 times to 0.99976 times on the mold surface with respect to the arrangement cycle P of the actual finished dimensions. The lens pattern 31 may be used. In other words, it is preferable to set the arrangement period Pm having a size reduced in the range of 0.027% to 0.072%. The greater the temperature difference from room temperature, the greater the degree of shrinkage.

  By manufacturing as described above, the three-dimensional image display columnar lens sheet 10 in which the dimensional change of the arrangement cycle of the unit columnar lenses 2 with time is small is easily manufactured.

[C] Material of columnar lens sheet for stereoscopic image display:
Hereinafter, the material surface of each component of the columnar lens sheet for stereoscopic image display will be further described.

[Base film]
The base film 1 is a transparent stretched film such as a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, an acrylic resin such as polymethyl methacrylate, a polycarbonate resin, a polyolefin resin such as polypropylene, a polyamide resin, or the like. A transparent resin film is mentioned. Among them, polyethylene terephthalate, which is a kind of polyester resin, is representative, and the biaxially stretched film is a suitable base film in terms of cost, transparency, mechanical strength, and the like. However, since molecular orientation is caused by stretching, by defining the tilt angle θ with respect to the orientation direction dm of the molecular principal axis as in the present invention, it can be used while preventing crosstalk over time.
In addition, although the base film 1 is "film shape", a "film" includes the concept of "sheet" and "plate" here, and these terms are based only on the difference in a name. , Are not distinguished from each other. That is, they are not distinguished by thickness or rigidity. For example, the thickness of the base film 1 is 50 μm to 1 mm or the like.

  By the way, although biaxially stretched polyethylene terephthalate film is a kind of typical stretched film as various films such as base film 1, the orientation direction dm of the molecular principal axis is generally different in the state of the belt-like film, particularly in the width direction. Is normal. For example, as shown in the plan view of FIG. 5, the alignment direction dm is generally inclined toward the both ends with respect to the alignment direction dm at the center of the width direction TD.

FIG. 5 shows an example of the distribution in the width direction TD of the orientation direction dm of the molecular principal axis in the wide continuous band-like film immediately after film formation of the stretched film before cutting to a predetermined width. When the columnar lens sheet 10 for stereoscopic image display is manufactured, a material obtained by cutting this wide continuous strip film into a continuous strip film having a predetermined width of 1000 mm or the like is used. At the time of this cutting, as shown in FIG. 5, the orientation direction dm of the molecular principal axis is different between the film C1 cut from the center in the width direction TD and the film C2 cut from near both ends in the width direction TD. become. When the orientation direction dm of the molecular principal axis is as parallel as possible in the flow direction MD, in other words, when the orientation angle γ is close to 0 °, the film C1 cut out from the center may be used.
In addition, the biaxially stretched polyethylene terephthalate film is usually formed by first laterally stretching in the sequential biaxial stretching and then longitudinally stretching to form a film, but when the degree of longitudinal stretching performed later is larger than the degree of lateral stretching. As a result, the influence of the longitudinal stretching remains strong, and the orientation direction dm of the molecular principal axis becomes stronger in parallel with the flow direction MD.

In addition, as the base film 1, a general-purpose and cost-effective film is used as much as possible, and thereby an in-plane distribution based on the non-uniformity in the orientation direction dm of the corresponding molecular principal axis is acceptable. It will be preferable to use it.
Therefore, as described above, in the present invention, it is more preferable that the inclination angle θ is 50 ° or less, more preferably 45 ° or less in the entire region of the base film 1, even though the inclination angle θ is not 0 °. And That is, the inclination angle θ is preferably 0 ° ≦ θ ≦ 50 °, and more preferably 0 ° ≦ θ ≦ 45 °.
In addition, it is effective to make the region where the inclination angle θ is 0 ° as close to the center as possible.

By making the inclination angle θ as described above, the dimensional change in the arrangement direction da of the unit columnar lenses 2 can be reduced more reliably, so that the crosstalk of the left and right parallax images and the light control pattern 6 of the laminated glass substrate are shielded from light. If it is a pattern, it will be more reliably prevented from being visible over time.
As described above, when the inclination angle θ between the orientation direction dm of the molecular principal axis and the ridge line direction dp of the unit columnar lens 2 is defined, how this influences the stability of the dimensional change of the unit columnar lens 2 positively. Is currently unknown, but anyway, it has been found that the dimensional change can be reduced.

(Unit columnar lens)
The unit columnar lens 2 is a columnar lens whose main cut surface has a shape such as a circle, an ellipse, a fence line, a hyperbola, a sine (wave) curve, a hyperbolic sine curve, an elliptic function curve, or a part of a cycloid curve. Typically, it is a so-called bowl-shaped lens. The unit columnar lens 2 having a bowl-shaped cross section is typically a lenticular lens. Note that the dimensions of the unit columnar lens 2 are combined with the columnar lens sheet 10 for stereoscopic image display, and the fineness of pixels of the image display element that displays a two-dimensional image, the arrangement period of the light beam control pattern 6, and stereoscopic viewing are enabled. The distance is determined according to the set distance of the observable range, the refractive index of the constituent material, and the stereoscopic method such as a two-lens method or a multi-view method.

  In addition, the “main cut surface” means the arrangement direction da of the unit columnar lenses 2 in a cross section parallel to the normal line n (see FIG. 1A) standing on one surface 1p of the base film 1. A parallel section. In other words, the cross section is parallel to the normal line n and perpendicular to the ridge line direction dp of the unit columnar lens 2. In FIG. 1A, the Z axis is parallel to the normal line n.

The unit columnar lens 2 is not made of an inorganic material such as glass but is made of a resin because it is inexpensive and easy to manufacture. If the unit columnar lens 2 is made of an inorganic material such as glass, crosstalk of the left and right parallax images due to dimensional changes does not occur.
As the ionizing radiation curable resin constituting the unit columnar lens 2, a known ionizing radiation curable resin such as an acrylate type or an epoxy type that is cured by ultraviolet rays or an electron beam is used.
By adopting an ionizing radiation curable resin, an uncured ionizing radiation curable resin liquid is brought into contact with one surface 1p of the base film 1 and the resin liquid is sandwiched between the mold and the base film 1 Thus, the unit columnar lens 2 can be easily formed by a molding method in which the resin is crosslinked and cured by irradiation with ionizing radiation. In addition, when using ionizing radiation curable resin for a resin liquid and making it harden | cure with ionizing radiation, it is called what is called 2P method (photopolymer method).
The 2P method is thermoplastic in that the curing of the ionizing radiation curable resin is quick and excellent in productivity, and above all, the shape of the unit columnar lens 2 that directly affects the stereoscopic image quality can be formed with high accuracy. It is superior to the thermoforming method using a resin, and is preferable for stereoscopic viewing that requires high accuracy.

  In the valley portion 2v between the unit columnar lenses 2 arranged on the base film 1, even if one surface 1p of the base film 1 is exposed, as shown in FIG. The one surface 1p may be covered with a resin constituting the unit columnar lens 2.

[Measurement of crosstalk]
Note that the crosstalk between the left and right parallax images may be performed visually, but can be measured, for example, by displaying white in the left eye image and displaying black in the right eye image. In this case, normally, it appears only white at the left eye observation position and black at the right eye observation position, but when crosstalk occurs, white is mixed with black at the left eye observation position, and black is white at the right eye observation position. Is mixed. By measuring this with an optical device such as a camera, it can be digitized.

[Use]
The use of the columnar lens sheet 10 for stereoscopic image display according to the present invention can be used for a stereoscopic image display device that displays an autostereoscopic image by being used together with an image display element that displays a planar image from which a stereoscopic image is based. . The image display element that displays a flat image is not particularly limited, and various known image display elements that perform flat image display such as a liquid crystal panel can be combined.
In the above description, the columnar lens sheet for stereoscopic image display 10 is arranged in front of the image display element, so that the left and right parallax images from the image display element are distributed to the left and right eyes of the observer, so-called lenticular type stereoscopic image. It explained on the assumption of the display. However, the columnar lens sheet 10 for stereoscopic image display is not particularly limited as long as it is used as a stereoscopic image display optical member for stereoscopic image display, more preferably for stereoscopic image display that can make use of its dimensional stability over time. . In this sense, the columnar lens sheet 10 for stereoscopic image display according to the present invention has a main cut surface shape in addition to a columnar lens whose unit columnar lens 2 is composed of only a curved surface, such as a lenticular lens. For example, even in the case of a columnar prism including a straight line such as a triangle, the effect of dimensional stability can be obtained.

  The application of the image display device incorporating the image display element using the stereoscopic image display lens sheet 10 of the present invention is not particularly limited as long as it is an application for displaying a stereoscopic image. For example, a stereoscopic display and a stereoscopic television. The three-dimensional display is a mobile phone, a portable information terminal, a portable or fixed game machine, a display unit of a personal computer, an electronic signboard, a digital photo frame, a medical display, and the like.

  Hereinafter, the present invention will be further described with reference to examples and comparative examples.

[Example 1]
As shown in FIG. 1A, a stereoscopic image display columnar lens sheet 10 having a columnar lens group 3 in which a plurality of bowl-shaped lenticular lenses are periodically arranged as a unit columnar lens 2 on a substrate film 1 as shown in FIG. It was produced using.
First, as a mold, as shown in FIG. 3, a metal cylinder-shaped (cylindrical) mold 30 having a columnar lens pattern 31 having a concave-convex shape opposite to the columnar lens group 3 made up of a large number of unit columnar lenses 2. Prepared. The columnar lens pattern 31 has a width of 900 mm in the direction of the cylindrical axis (cylinder height) of the mold 30, and the extending direction of the concave groove 32 having a concave and convex shape opposite to the unit columnar lens 2 is the circle of the mold 30. The pattern is parallel to the circumferential direction.

  Then, a transparent acrylic ultraviolet curable resin liquid is applied to the mold 30 rotating in the direction of the circular arc in FIG. 3 around the central axis of the cylinder, and a continuous belt-like substrate is further formed thereon. As a material film 1, a transparent strip-shaped biaxially stretched polyethylene terephthalate film (PET film) having a width of 1000 mm and a thickness of 125 μm is supplied, pressed against the mold 30 with a nip roller, and superimposed on the mold surface. The resin solution was cured by ultraviolet irradiation. Next, the base film 1 is released, and the unit columnar lens 2 extends in the MD direction of the base film 1 on the one surface 1p of the base film 1 with the ridge lines parallel to each other. A columnar lens sheet 10 for stereoscopic image display in which a columnar lens group 3 in which unit columnar lenses are periodically arranged in the TD direction was formed was produced.

At this time, when the orientation direction dm of the molecular principal axis of the continuous belt-like base film 1 is rotated by putting the base film 1 between two polarizing plates in a crossed Nicol state in which the polarization axes are orthogonal to each other. It was confirmed from the state of transmitted light.
The obtained continuous band-shaped columnar lens sheet 10 for stereoscopic image display has the alignment direction dm and the ridge line of the unit columnar lens 2 at the center position in the width direction TD perpendicular to the flow direction MD of the continuous band-shaped sheet. The inclination angle θ formed with the direction dp is 3 ° in the plane at the center in the width direction TD, and 26 ° in the plane at the side edge in the width direction TD. It was.

  The unit columnar lens 2 has a main cutting plane in which the main cutting surface has a height of 67 μm (elevation difference in the Z-axis direction between the valley portion 2v and the ridge line 2p), a curvature radius of 500 μm, and an F value of 1. It is a bowl-shaped lenticular lens whose surface shape is formed from a part of an ellipse. The unit columnar lens 2 has a width in the arrangement direction da and an arrangement period P of 500 μm, and completely covers one surface 1 p of the base film 1.

Next, from the continuous belt-like columnar lens sheet 10 for stereoscopic image display, a rectangular sheet-shaped columnar lens sheet 10a for stereoscopic image display having a rectangular shape (9:16 aspect ratio and a longitudinal direction dx of 718 mm) was cut out. As shown in the plan view of FIG. 6, the cut-out is performed in such a way that the longitudinal direction dx of the rectangular shape of the sheet-like columnar lens sheet 10a for stereoscopic image display is parallel to the width direction TD of the continuous belt-like sheet and the center of the longitudinal direction dx. However, it cut out so that it might become the center of the width direction TD of a continuous strip | belt-shaped sheet | seat. The ridge line direction dp of the unit columnar lens 2 in the sheet-like three-dimensional image display columnar lens sheet 10 a is a direction orthogonal to the rectangular longitudinal direction dx of the base film 1.
Therefore, also in the sheet-like three-dimensional image display columnar lens sheet 10a, the inclination angle θ is 3 ° at the center position in the longitudinal direction dx, which is the same as the inclination angle θ in the continuous belt-like sheet. In other words, with respect to the width L in the longitudinal direction dx of the base film 1 in a single wafer shape, the length measured from one end of both ends of the longitudinal direction dx of the rectangular shape is L / 2. In the center position in the width direction in the longitudinal direction dx, the inclination angle θ formed by the orientation direction dm and the ridge line direction dp of the unit columnar lens 2 is 3 °.
In addition, the orientation direction dm of the molecular principal axis in the central portion in the longitudinal direction dx of the rectangular shape is substantially orthogonal to the longitudinal direction dx of the rectangular shape of the base film 1 that is inclined by 87 ° (= 90 ° -3 °). Direction.

[Examples 2 to 4]
In Example 1, the central part of the continuous belt-like base film 1 in the width direction TD (after sheeting, the distance from one end of the width direction central part in the longitudinal direction dx of the base film 1 is The inclination angle θ formed by the orientation direction dm of the molecular principal axis at the position (L / 2) and the ridge line of the unit columnar lens 2 is changed to a minimum value of 3 ° and a maximum value of 26 ° in the plane. Example 2 has an in-plane minimum value of 32 ° and a maximum value of 44 °, Example 3 has an in-plane minimum value of 41 ° and a maximum value of 45 °, and Example 4 has an in-plane value of 44 °. Except that the minimum value of 47 ° and the maximum value of 50 ° were set to 50 °, a columnar lens sheet 10a for stereoscopic image display of a single-wafer sheet was produced through a continuous belt-like sheet in the same manner as in Example 1. The ridge line direction dp of the unit columnar lens 2 is a direction orthogonal to the longitudinal direction dx of the rectangular shape of the base film 1.

[Comparative Examples 1-2]
In Example 1, the central part of the continuous belt-like base film 1 in the width direction TD (after sheeting, the distance from one end of the width direction central part in the longitudinal direction dx of the base film 1 is The inclination angle θ formed by the orientation direction dm of the molecular principal axis at the position (L / 2) and the ridge line of the unit columnar lens 2 is changed to a minimum value of 3 ° and a maximum value of 26 ° in the plane. Comparative Example 1 displays a stereoscopic image in the same manner as in Example 1 except that the minimum value 56 ° and the maximum value in the plane are 68 °, and Comparative Example 2 is 63 ° and the maximum value is 72 °. A columnar lens sheet 10a was prepared. The ridge line direction dp of the unit columnar lens 2 is a direction orthogonal to the longitudinal direction dx of the rectangular shape of the base film 1.

[Performance evaluation]
The performance evaluation is performed as described above with reference to FIG. 2. The optical member 20 for stereoscopic image display, in which the glass substrate 5 is laminated on the back side of the columnar lens sheet 10 a for stereoscopic image display in the above-described single-wafer shape via the adhesive layer 4. Evaluated by.
For this reason, first, an adhesive film for optical materials (PANAC) using a transparent acrylic adhesive on the other surface 1q of the base film 1 which is the back surface side of the columnar lens sheet for stereoscopic image display 10a in the form of a single wafer. Kogyo Co., Ltd. product, PD-S1) was affixed, and the adhesive layer 4 with a thickness of 25 μm, the surface of which was protected with a separator film, was laminated.

Next, the separator film is peeled off from the columnar lens sheet for stereoscopic image display 10 a with the pressure-sensitive adhesive layer, and the columnar lens sheet for stereoscopic image display 10 a is pasted on one side of the transparent glass substrate 5 through the pressure-sensitive adhesive layer 4. In addition, a stereoscopic image display optical member 20 was produced.
In addition, a periodic light beam control pattern 6 is formed on the other surface of the glass substrate 5, and the period thereof is the 500 μm array period P of the unit columnar lenses 2 in the array direction da of the unit columnar lenses 2. The black pattern has a corresponding period and extends in the same direction as the ridgeline 2 p of the columnar unit lens 2. The light beam control pattern 6 is a black matrix that is a light shielding pattern in the color filter formed on the front glass substrate of the liquid crystal panel.
In the liquid crystal panel, one pixel is composed of red, green, and blue sub-pixels, and a black matrix is formed around the sub-pixels.

The above-described stereoscopic image display optical member 20 was subjected to a reliability test for 1000 hours in an environment of 80 ° C., and the degree of change in the arrangement period P of the unit columnar lenses 2 was measured and evaluated.
Note that the dimensional change is considered to be within an allowable range without causing a dimensional change that causes crosstalk if the stereoscopic display system is a twin-lens system and is 100 ppm or less. However, since the observable range in principle is limited to the front view etc., the main application is a small display device, but the accumulated error of the arrangement period P of the unit columnar lenses 2 is substantially reduced because of the small size. Since it is smaller than the large size and the observable range is limited such as the front, it does not matter much. When viewing on a large-scale television such as a large number of people, a multi-view system of about 10 is often adopted, and in the case of a 10-eye system, the dimensional change is allowed up to 300 ppm. .
Therefore, if this allowable error is applied to the arrangement period P of 500 μm, 100 ppm is 0.05 μm and 300 ppm is 0.15 μm. For this reason, the performance evaluation is good when the dimensional change is 0.13 μm or less (260 ppm or less) from the viewpoint of safety (◯ in Table 1), and slightly better when it is 0.15 μm or less (Δ in Table 1). ), Exceeding 0.15 μm was evaluated as defective (indicated by x in Table 1).

As shown in Table 1, Example 1 in which the inclination angle θ is 3 °, Example 2 in which the inclination angle θ is 32 °, and Example 3 in which the inclination angle θ is 41 ° are all targeted with a margin. It was below the dimensional change and was good. And Example 4 whose inclination angle (theta) is 47 degrees also stayed below the target dimensional change, and was somewhat favorable. However, Comparative Example 1 with an inclination angle θ of 56 ° and Comparative Example 2 with an inclination angle θ of 63 ° exceeded the target dimensional change and were defective.
For this reason, in each comparative example, when used in a stereoscopic image display device of a lenticular system, there is a possibility that luminance decreases due to crosstalk of left and right parallax images and visual recognition of a black matrix that is a light beam control pattern over time. However, in each embodiment, it is expected that a stereoscopic image with high quality can be displayed over time without causing a reduction in luminance due to crosstalk of the left and right parallax images or visual recognition of the black matrix.

1 Base film 1p One surface 1q The other surface 2 Unit columnar lens 2p Ridge (top)
2v Valley part 3 Columnar lens group 4 Adhesive layer 5 Glass substrate 6 Light beam control pattern 10 Columnar lens sheet 10a for stereoscopic image display Columnar lens sheet for stereoscopic image display (sheet-fed form)
20 Stereoscopic image display optical member 30 Mold 31 Columnar lens pattern 32 Unit columnar lens molding surface C1 of concave groove Film C2 cut at the center portion Film da cut at the end portion One direction (= array direction)
dm Orientation direction of molecular principal axis dp Ridge direction dx Longitudinal direction (during single sheet)
MD Flow direction L Width n in the arrangement direction Normal line P Arrangement period P Unit columnar lens molding surface arrangement period S Observer TD Width direction Tm Mold surface temperature θ Inclination angle (inferior of ridge line direction and molecular principal axis dm Corner)
γ Orientation angle (Inferior angle between flow direction MD and molecular principal axis dm)

Claims (1)

On one surface of the base film made of stretched film, the unit columnar lens has a columnar lens group in which ridge lines are arranged in one direction in parallel to each other, and the orientation direction of the molecular principal axis of the resin constituting the base film And the ridge line direction of the unit columnar lens, the inclination angle θ defined as a subordinate angle among the angles formed in a plane parallel to one surface of the base film is 0 ° throughout the base film. ≦ θ ≦ 50 °, a method for manufacturing a columnar lens sheet for stereoscopic image display,
On the mold surface as a mold, the unit columnar lens molding surface having an irregular shape opposite to that of the unit columnar lens is arranged, and a rotating cylindrical molding die having a columnar lens pattern having an irregular shape opposite to the columnar lens group is provided. The substrate film made of a continuous belt-like stretched film is supplied via an ionizing radiation curable resin liquid, and is superposed on the mold surface of the mold so that the columnar lens pattern is filled with the resin liquid. Then, the columnar lens group formed in close contact with one surface of the base film by irradiating ionizing radiation to cure the resin liquid and then releasing the base film When manufacturing the columnar lens sheet for stereoscopic image display consisting of:
On the mold surface, the orientation direction of the molecular principal axis of the resin constituting the continuous belt-shaped base film, and the ridge line direction on the unit columnar lens molding surface having a concave-convex shape opposite to the unit columnar lens of the cylindrical mold The columnar lens sheet for stereoscopic image display is manufactured by setting the inferior inclination angle θ formed by 0 ° ≦ θ ≦ 50 ° over the entire area of the columnar lens pattern on the mold surface.

Images