JP2007126339A - Ball for glass lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of scratches and digs harmful in the working of a glass ball, to stably produce a desired surface shape, further to eliminate defects of cracks, hollows and strains in the surface of a lens after forming as standard values required for the glass ball, and to make influence on the resolution of an image hard to appear. <P>SOLUTION: The glass ball has a ball diameter of ≥0.1 mm. Regarding surface shape precision, a size variation in diameter of a lot is set to 0.01 to 60 μm, a sphericity is set to 0.01 to 60 μm, a surface roughness (Ra) is set to 0.001 to 0.010 μm, scratches in the surface are controlled to ≤500 μm, and also, digs are controlled to ≤300 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is mainly a glass lens processed into a spherical or aspherical glass lens used in a general optical imaging field, such as a digital camera, an in-vehicle sensor camera, a projector, a DVD, a Blu-ray, a mobile phone with a camera, and an endoscope. The present invention relates to a glass ball used in a general optical communication field, such as a general purpose ball (hereinafter simply referred to as a glass ball) and an optical fiber connector.

  A conventional glass lens is generally called a gob, which is a lump of glass molded directly from a glass melt. This is heated and pressed, and a surplus portion is scraped off to make a spherical or aspherical lens. It was.

  However, it takes a lot of processing time and skilled techniques to process the surplus surface and finish it into a surface shape that can withstand use as a lens. Therefore, in order to solve these problems, recently, by utilizing the easy volume calculation that is a feature of glass balls, it is possible to reduce or eliminate a surplus portion after heat pressing, and processing is unnecessary or almost unnecessary after pressing. A molding method is employed.

  However, the lens used in the general optical imaging field must meet a certain standard for the surface shape of the glass ball when it is molded. This causes a problem that the resolution of the video is lowered.

Further, in a glass ball having a diameter of 0.3 to 10 mm used for an optical communication lens, the sphericity is 0.08 μm or less using a steel ball processing apparatus for ball bearings, and the difference in lot diameter is 0.13 μm. The following glass ball lenses have been proposed. (For example, see Patent Document 1)
However, a conventional ball processing apparatus for ball bearings uses a polishing disk made of a rigid body, and is not suitable for processing glass, which is a brittle material.
JP 2005-186232 A

  However, the glass ball lens according to the above proposal is mainly in the optical communication field where high accuracy is required, and the use in the general optical image field such as a digital camera and an in-vehicle sensor camera is not considered.

  The present invention pays attention to the above-mentioned actual situation, and particularly corresponds to the main use in the field of general optical imaging, and even if high accuracy as in the optical communication field is not required for this, Knowing that the requirements for other elements are closely related, and finding the accuracy of these elements and their accuracy, the general optical imaging field such as digital cameras, in-vehicle sensor cameras, DVDs, camera phones, etc. The objective of the present invention is to enable stable mass production of a desired surface shape with little influence on the resolution of an image in a lens after press processing as a lens in the field of optical communication requiring high accuracy.

  That is, the glass lens ball of the present invention suitable for the above-mentioned object is a glass ball having a sphere diameter of 0.1 mm or more, and the surface shape accuracy is 0.01 to 60 μm in the difference in diameter within the lot, and the sphericity is 0. A glass lens having a surface roughness (Ra) of 0.001 to 0.010 μm, a surface scratch (linear scratches) of 500 μm or less, and a dig (micro crack, dent) of 300 μm or less. Ball.

  The glass ball of the present invention has a reference value of the surface shape necessary for the glass lens (difference in the diameter within a lot of 0.01 to 60 μm, sphericity of 0.01 to 60 μm, surface roughness (Ra) of 0.001 to 0.00. 010 μm or less, scratch 500 μm or less, and jig 300 μm or less), and if the unevenness on the surface is within this range, the image resolution is hardly affected in the lens after press processing or the glass ball lens for optical communication. It has the effect that there is no problem in actual use.

  Hereinafter, specific embodiments of the present invention will be described.

  As described above, the glass ball of the present invention was found by identifying the range of the reference value of the surface shape necessary for the glass lens as described above, and as a result of attempting to produce a lens by heating and pressing glass balls of various surface shapes, It has been reached.

  In other words, the standard values obtained by the present invention are as follows: in a glass ball having a sphere diameter of 0.1 mm or more, the difference between the diameters in the lot is 0.01 to 60 μm and the sphericity is 0.01 to 60 μm. Furthermore, in addition, surface roughness, surface scratches (linear scratches), digs (microcracks, dents) are determined as standard values, and these surface roughness values (Ra) are 0.001 to 0. 0.010 μm, scratch on the surface is 500 μm or less, preferably 200 μm or less, and dig is 300 μm or less, preferably 100 μm or less.

  The above reference value must satisfy the surface shape of the glass ball when molding the lens, and if it exceeds that, defects such as cracks, dents and distortion will occur on the lens surface after molding, In the optical image field, it is inevitable that the resolution of the image will decrease. Further, when the glass ball is used as an optical communication lens without being molded, there is a possibility that the data communication becomes an obstacle.

  Note that a high-precision glass ball having a sphere diameter of less than 0.1 mm, a difference in diameter of less than 0.01 μm, and a sphericity of less than 0.01 μm is very expensive, so the above range is appropriate.

  FIG. 1 shows an example of an apparatus used for finishing the glass ball of the present invention (ball diameter of 0.1 mm or more). As shown in FIG. 1, the fixing as seen in a conventional ball bearing steel ball processing apparatus. A polishing machine comprising a combination of a disk and a rotating disk is used.

  Hereinafter, the surface processing apparatus shown in FIG. 1 will be described with reference to the drawing. In the figure, reference numerals 1 and 2 are disks facing each other, each having a groove 4 formed concentrically. A rotating disk and the other 1 is a fixed disk, and a glass ball B to be surface-processed flows between them, and the disk is rotated in a state of being sandwiched between the grooves, so that the glass balls B are moved along the grooves. Surface processing is performed by polishing while circularly moving. Then, the glass balls B processed between the two disks are discharged from the notch 3 of the fixed disk to the rotary conveyor 5 through the discharge chute 9, and the glass balls B are rotationally moved along with the rotation of the conveyor 5. It is fed through the chute 7 through the partition plate 6 and proceeds to the next processing.

  In the apparatus as described above, in the present invention, in particular, because of processing a brittle material such as a glass ball, at least one of the above-described two disks 1 and 2, for example, the fixed disk 1 is a rigid grindstone holder 1a as shown in FIG. The mating surface 10 having the concentric grooves 4 held is formed of an elastic body such as rubber or plastic, and is selected from cerium oxide, zirconium oxide, alumina oxide, silica, silicon carbide, and fine diamond powder. The elastic grindstone 1b contains one or more kinds of abrasive grains. In addition, instead of containing abrasive grains, when processing at least one as a low-rigid elastic body, the grinding fluid was selected from cerium oxide, zirconium oxide, alumina oxide, silicon carbide, silica, diamond powder 1 The same effect can be obtained by using loose abrasive grains mixed with seeds or more. A disk using an elastic body is not limited to the fixed disk side, but may be used on the rotating disk 2 side, or may be used on both the fixed disk and the rotating disk.

  Here, by forming the mating surface of at least one of the rotating disk and the fixed disk with an elastic body, the load applied to the glass ball sandwiched between the rotating disk and the fixed disk with rotation can be appropriately absorbed and relaxed. be able to. In other words, when processing the glass ball, if the load to press the disk somewhat strong, or even if the diameter of the glass ball is extremely larger than the clearance between both disks, because the sphericity of the glass ball at the initial stage of processing is poor, The load applied to the glass ball can be moderately relaxed by the elasticity of the elastic body. Therefore, there is little fluctuation in the load even when the glass ball with poor sphericity rotates, and the glass ball breaks, scratches and jigs The generation of glass balls with a small difference in diameter and a better sphericity becomes easier.

  The intended finishing accuracy can be obtained by changing the material and particle size of the abrasive grains contained in at least one elastic grindstone or the free abrasive grains of the grinding fluid during surface processing.

  Thus, by using such a surface processing apparatus, it is possible to obtain the glass ball of the present invention that conforms to the reference value of the surface shape accuracy required for the glass lens, while preventing the occurrence of harmful scratches and digs, and the desired surface shape. Is stably mass-produced.

It is a schematic diagram which shows one example of the surface processing apparatus for obtaining the glass ball which concerns on this invention. It is a perspective appearance figure showing an example of an elastic grindstone.

Explanation of symbols

1: Fixed disk 1a: Rigid body grindstone holder 1b: Elastic body grindstone 2: Rotating disk B: Glass ball

Claims (1)

  A glass ball having a sphere diameter of 0.1 mm or more, the surface shape accuracy being 0.01-60 μm for the difference in diameter within the lot, 0.01-60 μm for the sphericity, and surface roughness (Ra ) Is 0.001 to 0.01 μm, surface scratches (linear scratches) are 500 μm or less, and digs (microcracks, dents) are 300 μm or less.

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