JPH0532857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing an exposure correction lens used in manufacturing a fluorescent surface of a color cathode ray tube.

BACKGROUND ART AND PROBLEMS When manufacturing the fluorescent surface of a color cathode ray tube using photographic technology, a correction lens for exposure such as an axially symmetrical or axially asymmetrical aspherical lens or a taper prism is generally used.

This correction lens has conventionally been manufactured as follows.

That is, taking an aspherical lens as an example, first, as shown in FIG. 1A, a curved surface 1 identical to the required lens curved surface is
A molding die 2 having the following is prepared. Next, as shown in FIG. 1B, a flat optical glass material whose upper and lower surfaces are parallel (so-called parallel flat optical glass material) is placed on the molding die 2 coated with a mold release agent 3. Figure 1C
As shown in FIG. 2, the glass material 4 is softened in an electric furnace and suspended over the curved surface 1 of the molding die 2. As a result, a correction lens material 6 whose upper surface 5 is thermoplastically deformed in accordance with the curved surface of the molding die 2 is obtained (see FIG. 1D).

Next, as shown in FIG. 1E, a polishing plate 9 is placed on the surface plate 7 with the block 8 interposed therebetween. The correction lens material 6 is placed on the polishing plate 9 with the lower surface 10 in contact with the molding die 2 facing upward, and the reference line 12 on the side surface of the correction lens material 6 is traced using the height gauge 11. Meanwhile, the gap gauges 1 at three locations are inserted between the correction lens material 6 and the polishing plate 9.
3 to maintain the correction lens material 6 in a predetermined state.

The problem with this process is that there are dimensional errors in the parts themselves such as the block 13 and the polishing plate 9 placed between the surface plate 7 and the correction lens material 6, and the correction lens material 6
Errors occurred in various parts when tracing the side reference line 12 with the height gauge 11, and the sum of these factors resulted in an error with the horizontal reference in the correction lens design, worsening the lens characteristics. It is. In addition, according to the above process, it takes time to install the three gap gauges 13 between the correction lens material 6 and the polishing plate 9 while measuring a predetermined height with the height gauge 11, resulting in poor work efficiency. It was.

Next, as shown in FIG. 1F, the correction lens material 6
By pouring the molten optical pitch 14 into the gap between the lens material and the polishing plate 9 and around the correction lens material 6, and cooling with water until the entire body reaches room temperature,
The correction lens material 6 is fixed.

The problem with this process is that the molten and poured optical pitch 14 contracts as it cools.
Adhesion distortion also occurs in the correction lens material 6, and when the correction lens material 6 is polished in this state and then removed from the polishing plate 9, the flatness will definitely deteriorate by the amount of distortion.

Next, as shown in FIG. 1G, the surface cutting machine 15
After placing and fixing the correction lens material 6 fixed on the polishing plate 9 on the magnetic base 16 of Cut and planarize.

The problem with this process is that when cutting with the diamond cup wheel 17, a certain amount of load is applied, so both the optical pitch 14 and the correction lens 6 are cut while being elastically deformed. When it is removed, it returns to its original state by the amount of this deformation, reducing the flatness of the cut surface.

Next, as shown in FIG. 1H, the correction lens material 6
The cut surface is placed on the polishing table 19 of the polishing machine 18 with the cut surface facing down, and while applying a load with a weight 20, an abrasive is used to polish the cut surface with sand to a mirror surface where blade marks have been generated. Thereafter, the optical pitch 14 is removed and removed from the polishing plate 9 to obtain the desired correction lens 21.

The correction lens 21 obtained in this way has
Since the optical pitch 14 is cut with distortion due to contraction and polished with elastic deformation caused by the diamond cup wheel 17, the superimposed processing deformation is removed after the correction lens 21 is removed. The flatness of the surface deteriorates,
Therefore, there is a drawback that the quality of the correction lens 21 becomes unstable.

OBJECTS OF THE INVENTION In view of the above-mentioned points, the present invention provides a method for manufacturing a correction lens that can obtain a correction lens with stable quality.

Summary of the Invention The present invention involves placing a parallel plate-shaped glass material on a molding die having the same curved surface as a required lens curved surface,
The correction lens material is softened to obtain a correction lens material, and this correction lens material is turned upside down and held in a polishing receiving mold having a curved surface complementary to the molding die, which is opposite to the required lens curved surface of the correction lens material. This is a method for manufacturing a correction lens characterized by flat-polishing the surface.

According to the above invention, it is possible to manufacture a correction lens in which the errors and variations in the reference horizontal plane are greatly reduced, and which is plane-polished with high precision.

Embodiments Hereinafter, embodiments in which the present invention is applied to an aspherical lens which is an exposure correction lens similar to that described above will be described with reference to the drawings.

In the present invention, first, as shown in FIG. 2A, a molding die 32 having a curved surface 31 identical to the required lens curved surface and a curved surface complementary to this molding die 32, that is, the molds are superimposed on each other. At this time, a polishing receiving mold 34 having a curved surface 33 in which both curved surfaces are in close contact with each other without a slight gap is manufactured using an NC milling machine.

Next, as shown in FIG. 2B, a parallel plate-shaped optical glass material 3 having a predetermined thickness is placed on a molding die 32 coated with a mold release agent 3 such as fine alumina powder.
5, this glass material 35 is heated in an electric furnace and is made to hang down on the curved surface of the mold 32. By hanging down the glass material 35, a correction lens material 38 is obtained in which the upper surface 36 and the lower surface 37 are thermoplastically deformed along the curved surface 31 of the molding die 32, as shown in FIG. 2C. Thereafter, as shown in FIG. 2D, the correction lens material 38 is removed from the molding die 32, and the curved surface of the upper surface 36 of the correction lens material 38 is examined using an aspheric lens measuring machine.

Next, as shown in FIG. 2E, this correction lens material 38 is turned upside down so that the lower surface 37 to which the milling marks of the molding die 32 are transferred faces upward, and adhesive is applied to the surface. It is held in close contact with a polishing receiving mold 34 coated with a thin layer of paint. At this time, the curved surface 33 of the polishing receiving mold 34 and the upper surface 36 of the correction lens material 38 are in close contact with each other without any gaps since they are complementary curved surfaces.

Next, as shown in FIG. 2F, the correction lens material 3
8 is fixed to the polishing receiving mold 34 by the surface cutting machine 1.
5, the lower surface 37 of the correction lens material 38 is cut by a set amount using a diamond cup wheel 17 to flatten it. 39 is the cutting surface.

Next, as shown in FIG. 2G, the correction lens 40 is placed on the polishing table 19 of the polishing machine 18 with the cutting surface 39 facing down.
The cut surface 39 is polished into a flat surface using an abrasive material made of free abrasive grains while applying a load with a weight 20.

Next, after the correction lens 40 is removed from the polishing receiving mold 34, surface clouding removal polishing, ultrasonic cleaning, etc. are performed to obtain the intended correction lens 40.

According to the above-described correction lens manufacturing method, the correction lens material 38 is directly attached to the polishing receiving mold 34 having a curved surface complementary to the molding die 32, and the polishing receiving mold 34 is passed through the surface cutting machine 15. By arranging it above, the error between the design reference level of the correction lens and the actually obtained horizontal plane of the polished surface of the correction lens 40 and the variation in the error from correction lens to correction lens are greatly reduced. At the same time, the correction lens material 3 is placed in the polishing receiving mold 34.
8, since the curved surface 33 of the polishing receiving mold 34 is complementary to the curved surface 36 of the correction lens, it can be held securely even if the adhesive is applied thinly. The thin adhesive film prevents elastic deformation due to the load during cutting and polishing, allowing highly accurate surface polishing.
Therefore, the correction lens 40 obtained by this manufacturing method
The quality is extremely stable compared to correction lenses manufactured using conventional methods. As a result, when light passes through the correction lens 40 obtained by this manufacturing method, the actual arrival position of the light and the designed arrival position will substantially match. Further, according to the present manufacturing method, cutting and polishing work of the correction lens material 38 becomes easy, so polishing efficiency is improved. In addition, although the surface 37 of the correction lens material 38 in contact with the molding die 32 has a transfer of the milling marks of the curved surface 31 of the mold 32, this surface 37 is flat-polished, and the correction lens material 38 has a surface polished as a lens curved surface.
Since the upper surface 36 is not in contact with the molding die 32, a correction lens with high smoothness and high accuracy can be manufactured.

Application Example In the above example, the present invention was applied to manufacturing an aspherical lens, but it can also be applied to manufacturing a taper prism, which is a type of correction lens.

Effects of the Invention According to the present invention, a polishing receiving mold having a curved surface complementary to the molding die is prepared, and the correction lens material is held on the front surface of the curved surface of the polishing receiving mold and flat-polished. , a correction lens having a highly accurate reference level and flatness can be obtained. Also, according to this manufacturing method,
Since the cutting and polishing operations are simplified, the operating time can be shortened.

[Brief explanation of the drawing]

1A to 1H are process diagrams for explaining a conventional method for manufacturing a correction lens, and FIGS. 2A to 2G are process diagrams for explaining a method for manufacturing a correction lens according to the present invention. 32 is a molding die, 34 is a polishing receiving die, 35 is a glass material, 38 is a correction lens material, and 40 is a correction lens.

Claims (1)

[Claims] 1 Place a parallel plate-shaped glass material on a molding die having the same curved surface as the required lens curved surface, soften it to obtain a correction lens material, and invert the correction lens material vertically to complement the above-mentioned molding die. A method for manufacturing a correction lens, which comprises holding the correction lens material in a polishing receiving mold having a curved surface, and polishing the surface of the correction lens material opposite to the desired lens curved surface.