JPS5929406B2 - Method for manufacturing a plate-shaped body having corresponding shapes on both sides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lenticular lens used in a rear projection projection device for viewing from a surface opposite to a projection surface.
The present invention relates to a method for producing a plate-shaped body having corresponding shapes on both sides, which is suitable for application to shaped screens.

First, before explaining the method of the present invention, a three-tube projector using a lenticular rear screen shown in FIG. 1 will be explained. 1 projects three primary color images of "red", "green" and "blue". Shows cathode ray tube group, IR is "red",
IG is a cathode ray tube that projects a "green" image, and IB is a cathode ray tube that projects a "positive" image.

2R is a main lens installed on the optical axis of the cathode ray tube IR, 2G is a main lens corresponding to the cathode ray tube IG, and 2B is a main lens corresponding to the cathode ray tube IB.

Reference numeral 3 indicates a correction lens, and reference numeral 4 indicates a lenticular rear screen arranged in a single row in the vertical direction.
The optical axes of the light beams from R, IG, and IB are all set to coincide with the lenticular surface of the lenticular rear screen 4.

The correction lens 3 changes the optical path of the projected light beams 8R, 8G, and 8B that have been expanded and diverged from the main lenses 2R, 2G, and 2B into parallel light beams at predetermined optical path positions, and projects them onto the lenticular rear screen 4. Lenses are one example. The lenticular rear screen 4 has a large number of generally known so-called semicylindrical convex lenses 4a arranged in parallel, and in this case, the semicylindrical convex lenses are arranged in parallel in the horizontal direction. Convex lens 4 of this rear screen 4
A stripe-shaped light shielding portion 4b is attached to the surface opposite to the surface where a is provided to block external light. Note that this structure excludes the explanation of the horizontal component of each luminous flux. 8R
is the optical axis from the red cathode ray tube IR, and 8G is the optical axis from the green cathode ray tube I.
The optical axis from G and 8B represent the optical axis from the blue cathode ray tube IB, respectively.

According to this configuration, the luminous flux from each cathode ray tube, that is, the emitted luminous flux of the green cathode ray tube IG is diffused with a diffusion angle (direction angle) θG centering on the optical axis 8B, and the emitted luminous flux of the red cathode ray tube IR is is the diffusion angle (direction angle) θR centered on the optical axis 8G.
The emitted light beam from the blue cathode ray tube IB is on the optical axis 8.
The light is diffused with a diffusion angle (direction angle) θB centering on R. Therefore, since the directions of the optical axes of each color light beam are different, the range W in which a composite image of primary color images from each cathode ray tube, that is, a color image can be viewed in a well-balanced state, becomes narrow, and in other ranges, So-called color shading occurs depending on the viewing angle, making it impossible to obtain an original color image. Therefore, to explain the lenticule-shaped screen 25 in which the color shading does not occur, this lenticule-shaped screen 25 is
As shown in the figure, the first surface 26 is a lenticule in which a large number of semicylindrical convex lenses 26a are arranged in parallel to obtain a predetermined directivity angle that determines the field of view of the screen. The radius of curvature R2 of each semicylindrical convex lens 26a is a circular arc surface, and the interval P2 between each convex lens 26a is 0.8 squares. Further, the second surface 27 also has a similar shape to the first surface 26, and the convex lens of the first surface 26 and the second surface 27
The convex lenses correspond to each other in position. Further, the distance 13 between the convex lenses on the first and second surfaces is 3 m11. According to the lenticule type rear screen as described above, as shown in FIG. 3, the parallel light beams 8R, 8G,
8B is divided by the semicircular convex lenses 26a of the first surface 26 of the screen 25, and each semicircular convex lens 2
Each light beam corresponding to 6a is converged, condensed into a line almost on the surface of the second surface 27, and further diverged.

That is, the parallel light beam from the cathode ray tube 1G that enters the screen 25 at right angles is reflected by each convex lens 2 on the second surface 27.
7a, and is then diverged at a vertical direction angle 2θ (=±12in) perpendicular to the screen 25. Further, the parallel light beam from the cathode ray tube 1R, which enters the screen 25 while maintaining the depression angle 81, is transmitted to the second surface 27.
The light is focused at a position below each convex lens 27a, and is then diverged at a vertical direction angle 2θ (=±12 inches) perpendicular to the screen 25.

Further, the parallel light flux from the cathode ray tube 1B that enters the screen 25 while maintaining an elevation angle of 8 is focused at a position above each convex lens 27a on the second surface 27, and then
5 with a vertical directivity angle 2θ (=±12in). That is, even if the directions of the optical axes of the respective optical paths are different, the directions of the divergence centers of each color on the screen surface are the same, so no color shading occurs. Although the optical path diagram shown in FIG. 3 is for one convex lens, the same optical path occurs for all convex lenses. Therefore, by using a screen having lenticules on both sides, a color image without color shading can be obtained.

However, the centers of each convex lens of the lenticule formed on both sides of the screen must match with an error within ±0.01 mm to 0.03 mm over the entire surface on both sides. It was difficult to align the first position. Conventionally, it has been considered to form lenticules on both sides of the screen by, for example, providing a frame in the lower mold and inserting the upper mold into this frame. However, with this method, there is no correspondence between the upper and lower molds against mold deformation, so the upper and lower molds deform independently due to pressure, temperature changes, etc. The center of the Kyura lens was shifted, making it unusable. In view of the points related to the present invention, it is an object of the present invention to provide a method for manufacturing a plate-shaped body having corresponding shapes on both sides, which can manufacture a lenticule-shaped rear screen with almost no color shading as described above. It is something to do.

Examples of the method of the present invention will be described in detail below.

FIG. 4 shows molds 12 and 13 for manufacturing a lenticule-shaped rear screen on the surface of the table 11 of the machine tool 10.
This figure shows the installation. Machine tool 1
Since the mold itself is large, 1 m or more in length and 80 cm or more in width, a large mold such as a planing machine or a plano mill is used. The material of the molds 12 and 13 to be cut is preferably a material that is relatively easy to cut, such as aluminum or brass plate. Both molds are an upper mold or a lower mold, respectively. After fixing the upper and lower molds 12 and 13 on the table 11 so that their end surfaces match, first use a positioning rod to maintain the linearity of the upper and lower molds 12 and 13 and the pitch accuracy of the entire lenticule, which will be explained later. The groove 14 is cut out with a tool 15 such as an end mill or a cutting tool.

The positioning rod groove 14 has a substantially semicircular cross-sectional shape, and when the upper and lower molds 12 and 13 are matched, it is configured to have a circular shape including a predetermined thickness. Make sure to create streaks. Next, positioning grooves 1 provided on both sides
4, both molds 12 and 13 are rolled with a roller 16 having the shape of the end face of a lenticule. This roller 1
As shown in FIG. 5, 6 is a horizontal roller fixed to a spindle 17, and the pitch P1 of each peak is 0.8 mm, and the radius of curvature r1 of each peak is 1 mm. Therefore, both molds 1
2 and 13, the groove 14 and the uneven surface 18 for the lenticule are rolled in one operation. Note that the processing of the lenticule mold surfaces of both molds 12 and 13 may be performed by cutting with a cutting tool instead of rolling. The upper and lower molds 12 and 13 thus manufactured are assembled into a heat press apparatus 20 shown in FIG. 6.

This heat press device 20 is used to manufacture a screen for the lenticule. Reference numeral 21 indicates the material of the screen for the lenticule, and 22 and 23 indicate heaters for heating the upper and lower molds 12 and 13, respectively. There is. 24 is a positioning rod, and this positioning rod 24 and the upper and lower molds 12, 1
3, the predetermined interval t is maintained.

The screen material 21 for the lenticule is made of acrylic resin or vinyl chloride resin, and the screen 25 obtained after pressure molding has a vertical dimension 11 of, for example, 68 mm.
6, the horizontal dimension 12 is 914 m71 (so-called 45I type projection screen). Next, to explain the manufacturing process of the lenticule type screen,
A material 21 such as the above-mentioned acrylic resin is placed between the lower molds 22 and 23. The thickness of this material 21 is set to be slightly larger than the aforementioned t dimension. In other words, the t dimension is comparable to the final thickness when the screen 25 is completed, and therefore it is necessary to fill the space corresponding to the uneven surface, so the t dimension is set to be slightly larger than the t dimension. The screen material 21 set at a predetermined position is held and pressed by the upper and lower molds 12 and 13, and heated by the heaters 22 and 23.

In this case, the heating temperature should be 150°C to 170°C, and the pressing force should be 50kg/Cl to 1001<g
/d. When the lenticules are formed on both sides of the screen by the method described above, the convex lenses of the lenticules on both sides can be aligned extremely accurately for the following reason.

In other words, even if the upper mold tries to deform due to pressure or heat while pressing the screen material with the upper and lower molds, the upper mold is connected to the lower mold by the positioning rod, so the upper mold will not deform. Since the lower mold also deforms as the mold deforms, relative errors between the lenticular lenses on both sides do not occur. In other words, the center position of the double-sided convex lens does not shift. Although an absolute error occurs at this time, there is no problem as long as the relative positions of the lenticules on both sides of the screen match. FIG. 7 shows an example of a rear screen for a lenticule that can be obtained by the method of the present invention.

The size of this screen 28 is the same as the screen in the example shown in Fig. 2, with a vertical dimension 11 of 686 mm and a horizontal dimension 12 of 914 mm.
It is. The first surface 29 is a lenticular structure in which a large number of vertically extended so-called semicylindrical convex lenses 29a are arranged in parallel in order to obtain a predetermined directivity angle that determines the field of view of the screen. And each semicylindrical convex lens 2
The radius of curvature R3 of the lens 9a is a 0.4-square arc surface, and the interval P3 between each convex lens 29 is 0.6 mm. On the other hand, the second surface 30 has an uneven surface 30a to which a black stripe for blocking external light can be easily attached. The convex portions of the uneven plane 30a are provided in parallel in the vertical direction at intervals corresponding to the interval P3 of the convex lenses 29a of the first surface 29,
The ratio between the distance 14 between each convex portion and the width dimension 15 of the convex portion itself is 1:2. Note that the thickness 16 is 1.0 mm. As described above, according to the method of the present invention, positioning grooves are provided at the ends of a pair of corresponding molds so as to face each other between the pair of molds, and each positioning rod is provided between the positioning grooves. and sandwiching the object to be molded between the pair of molds, and pressing the pair of molds together to produce a plate-shaped body having a predetermined shape corresponding to each side on both surfaces. Therefore, the compatibility of the lenses on both sides is extremely good, and therefore a lenticule-shaped rear screen in which color shading is less likely to occur can be manufactured.

That is, the cause of color shading on the rear screen is the mismatch in the directions of the divergence centers of the luminous flux of each color on the screen surface, so in order to eliminate this cause, the directions of the divergence centers must be made coincident.

However, in practice, it is difficult to uniformly provide a screen with a pitch of about 1 mm over a range of about 1 m, and it is even more difficult to do so with a rear screen having a single lenticule on the front and back surfaces. However, in the method of the present invention, the pitch of each peak of the lenticule can be made uniform over a wide range with the above-mentioned configuration. Furthermore, according to the present invention, the linearity of the semi-cylindrical uneven surface can be made uniform by the action of the positioning rod, while the pitch of each peak can be made accurate, and the stopper can also be used to make the wall thickness of the molded product uniform. As a result, most of the above drawbacks are eliminated.

[Brief explanation of drawings]

Figure 1 is a route diagram for explaining a three-tube projector using a lenticule type rear screen, Figure 2 is an enlarged perspective view of the main parts showing an example of a lenticule type rear screen, and Figure 3 is a 2-tube projector using a lenticule type rear screen. FIG. 4 is an enlarged front view for explaining the optical path using the screen shown in the example; FIG. 4 is a perspective view for explaining the method of manufacturing a mold; FIG. 5 is an enlarged front view for explaining an example of a rolling roller; FIG. 7 is a schematic front view showing an example of a heat press device, and FIG. 7 is an enlarged perspective view of the main parts showing another example of a lenticular type rear screen. 10 is a machine tool, 12 is an upper mold, 13 is a lower mold, 14 is a positioning recess, 15 is a tool, 20 is a heat press device, 21 is a screen material, 24 is a positioning rod, and 25 is a screen.

Claims (1)

[Claims] 1. At each end of a pair of corresponding molds, a pair of long positioning grooves having a circular arc cross section are provided, which face each other between the pair of molds and extend in a direction parallel to the opposing surfaces. A predetermined uneven surface is formed on the opposing surfaces, a positioning round bar is interposed between the pair of long grooves for positioning, and a thermoplastic molded object is clamped between the pair of molds. A method for producing a plate-like body having corresponding shapes on both sides, the method comprising: manufacturing a plate-like body having predetermined shapes corresponding to each other on both sides by pressing molds together in a heated state.