JP2011001216A - Method and apparatus for removing strain of glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely remove the strain of a glass substrate without attaching soil, unevenness or the like.SOLUTION: Press plates 14 each having a flat surface having ≥10 μm and ≤100 μm surface roughness and the glass substrates 16 are alternately superimposed and are piled up in a plurality of stages on an inclined surface 13a of an inclined table. The press plate 14 has an annealing point higher by ≥50°C than the annealing point of the glass substrate 16. A weight 18 is placed on the press plate 14 positioned uppermost. As a result, both surfaces of the glass substrate 16 are pressed by the flat surfaces 14a of the press plate 14. The glass substrate 16 having both surfaces pressed by the flat surfaces 14a of the press plate is annealed in a heating furnace 11.

Description

  The present invention relates to a distortion removal method and apparatus for a thin glass substrate used for an incident angle limiting filter for limiting an incident angle of light from a subject.

  In recent years, small image scanners for reading documents and the like have been incorporated into small electronic devices such as mobile phones and laptop computers. In a small image scanner, a subject such as a document and an image sensor are close to each other, but light from each part of the subject enters not only the imaging area corresponding to each part but also the surrounding imaging area. Sometimes. Therefore, by providing an incident angle limiting filter for limiting the incident angle of light in the image sensor, light from each part of the subject is surely incident on an imaging area corresponding to each part.

  In the incident angle limiting filter, a multilayer film in which holes for light incidence are provided at regular intervals is formed on both surfaces of a transparent glass substrate. A very thin glass substrate having a thickness of about 0.5 mm (for example, D263 manufactured by Schott) is used as the glass substrate, and the glass substrate is mainly manufactured by a downdraw method or the like. Therefore, the glass substrate after manufacture is distorted such that the surface is warped due to its thin thickness. If a glass substrate with such distortion is used for the incident angle limiting filter, the distance to the image sensor changes between the part where the distortion occurred and the part where it did not occur, causing the uneven brightness of the image and stray light. It becomes. Therefore, when manufacturing the incident angle limiting filter, the glass substrate is preliminarily removed and the glass substrate is flattened.

  In this regard, in Patent Document 1, when annealing a glass substrate mounted on a plasma display panel (PDP) or a liquid crystal display (LCD), both surfaces of the glass substrate are pressed with a flat carbon plate. Thus, the distortion of the glass substrate is removed and flattened.

JP 2006-16265 A

  However, in the strain removal method of Patent Document 1, the glass substrate is sandwiched between carbon plates, so that the glass substrate is easily contaminated. Further, since the carbon plate has uneven surface roughness, when the glass substrate is sandwiched between the carbon plates, the unevenness of the carbon plate may be transferred to a part of the glass substrate. As described above, a glass substrate having a glass substrate with dirt or irregularities is not suitable as a glass substrate for an incident angle limiting filter as it is, and therefore, dirt and irregularities are removed in addition to the original filter manufacturing process. A process is required separately, which takes time.

  It is an object of the present invention to provide a glass substrate distortion removing method and apparatus that can reliably remove distortion of a glass substrate without adding dirt or irregularities.

  In order to achieve the above object, the method for removing strain of a glass substrate of the present invention comprises alternately stacking a glass substrate and a press plate made of a glass material having an annealing point that is 50 ° C. higher than the annealing point of the glass substrate. In addition, by stacking a plurality of stages together, both surfaces of the glass substrate are pressed by the flat surface of the press plate, and the glass substrate pressed on both surfaces is subjected to an annealing treatment. Here, the annealing point (annealing point) refers to a temperature at which the internal stress of the glass is substantially relaxed within a few minutes and almost disappears.

  The press plate and the glass substrate are stacked obliquely on an inclined table having an inclined surface inclined at a constant angle, and a support rod attached to a side surface on the lower end side of the press plate in a direction orthogonal to the inclined surface. Even if air enters between the press plate and the glass substrate during stacking because the weight is placed on the top press plate, the press plate and Since the glass substrate does not slide down, the press plate and the glass substrate can be reliably stacked. The press plate is preferably a quartz plate. Further, the surface roughness Ra of the flat surface is preferably 10 μm or more and 100 μm or less.

  The strain relief device for a glass substrate of the present invention is made of a glass material having an annealing point that is higher by 50 ° C. or more than the annealing point of the glass substrate. It has a plurality of press plates which press both surfaces with a flat surface, and an annealing treatment means for performing an annealing treatment on the glass substrate whose both surfaces are pressed.

  An inclined base in which the press plate and the glass substrate are obliquely stacked on an inclined surface inclined at a certain angle, and a side surface on the lower end side of the press plate are supported in a direction orthogonal to the inclined surface. It is preferable to provide a support rod and a weight placed on the press plate located at the top.

  According to the present invention, both sides of a glass substrate are pressed with a press plate made of a glass material having a flat surface with a surface roughness Ra of 10 μm or more and 100 μm or less and an annealing point higher by 50 ° C. than the annealing point of the glass substrate. In addition, since the glass substrate is annealed in this pressed state, distortion such as warping of the surface is surely removed without attaching dirt or irregularities to the glass substrate and without generating bubble marks or cracks. Thus, the glass substrate can be planarized.

It is sectional drawing which shows the distortion removal apparatus of the glass substrate of this invention. It is an expanded sectional view of a press board.

  As shown in FIG. 1, the glass substrate strain removing apparatus 10 of the present invention includes a heating furnace 11, an inclined table 13, and a plurality of press plates 14, and when the glass substrate 16 is annealed in the heating furnace 11. The distortion of the glass substrate 16 is removed by pressing both surfaces of the glass substrate 16 with the flat surface 14 a of the press plate 14. The glass substrate 16 is used for an incident angle limiting filter incorporated in a small image scanner, and is a thin glass substrate having a thickness of 0.1 mm to 0.5 mm. In addition, the thin glass substrate of D263 made by Schott, which is an example of the glass substrate, has a thickness of about 0.145 mm, and has a large warpage. Therefore, when using D263 or the like as an optical component, it is necessary to perform some kind of flattening process.

  The inclined table 13 has an inclined surface 13a inclined at a certain angle, and the press plates 14 and the glass substrate 16 are alternately stacked on the inclined surface 13a and stacked in a plurality of stages. A weight 18 is placed on the press plate 14 located at the top. As a result, the glass substrate 16 is sandwiched between the upper and lower press plates 14, and both surfaces of the glass substrate 16 are pressed by the flat surface 14a of the upper press plate and the flat surface 14a of the lower press plate. Is done. A support rod 20 is attached to the tilt table 13 in a direction orthogonal to the tilted surface 13 a, and the support rod 20 supports the side surface on the lower end side of each press plate 14.

  The press plate 14 is made of a quartz plate made of silicon dioxide. Compared with a glass plate having other components in addition to silicon dioxide, the press plate 14 is extremely small in deformation and stable against sudden changes in temperature. Further, the annealing point of the press plate 14 is set higher by 50 ° C. or more than the annealing point of the glass substrate 16. Therefore, when the annealing process is performed in a state where both surfaces of the glass substrate 16 are pressed by the press plate 14, the press plate 14 is not deformed even if the annealing point of the glass substrate 16 is reached. Accordingly, the state of the flat surface 14a of the press plate 14 does not change even under the high temperature of the annealing process, so that the distortion of the glass substrate 16 can be reliably removed.

ここで、「数１」のLは、図２に示すように、プレス板の平坦面１４ａのうち任意に選んだ一定区間の距離（基準長さ）を表している。ｆ（ｘ）は、基準長さL間における平坦面１４ａの凹凸を示す粗さ曲線２２上の点と、粗さ曲線２２における凹凸の平均的な高さを示す平均線２４との間の距離を表している。 Further, the flat surface 14a constituting both surfaces of the press plate 14 has a surface roughness Ra expressed by the following [Equation 1] of 10 μm to 100 μm, more preferably 50 μm.

Here, L in “Equation 1” represents a distance (reference length) of a certain section arbitrarily selected in the flat surface 14a of the press plate, as shown in FIG. f (x) is a distance between a point on the roughness curve 22 indicating the unevenness of the flat surface 14a between the reference lengths L and an average line 24 indicating the average height of the unevenness in the roughness curve 22. Represents.

  By setting the flat surface 14a of the press plate within the above range, even if both sides of the glass substrate 16 are pressed by the press plate 14, the glass substrate 16 is flattened without transferring irregularities onto the glass substrate 16. . On the other hand, when the surface roughness Ra of the flat surface 14a exceeds 100 μm, the unevenness formed on the flat surface 14a may be transferred to the glass substrate 16. On the other hand, when the surface roughness Ra of the flat surface 14a is less than 10 μm, the flat surface 14a is almost equivalent to a mirror surface, so that the flat surface 14a and the glass substrate 16 are adsorbed, and the glass substrate 16 may be broken by the adsorption. There is.

  On the other hand, in Patent Document 1, as in the present application, the glass substrate is flattened during the annealing process. However, since a carbon plate with uneven surface roughness is used, carbon is partially formed on the glass substrate. The unevenness of the plate may be transferred. In addition, since the carbon plate may burn and deform when exposed to a high temperature condition in the heating furnace, it is necessary to feed nitrogen into the heating furnace and purge the air in the heating furnace (nitrogen gas purge). The cost was very high.

  On the other hand, since the press plate 14 used in the present application is easy to process, it is possible to make the surface roughness uniform. Therefore, the entire flat surface 14 a of the press plate can be suppressed to a surface roughness Ra of 100 μm or less without the possibility that the unevenness of the press plate 14 is transferred onto the glass substrate 16. In addition, the price of the press plate 14 made of a quartz plate is lower than that of the carbon plate, and the cost required for blasting for adjusting the surface roughness of the press plate 14 is the nitrogen required when using the carbon plate. Even compared to the cost of gas purge, it is very small.

  Next, the operation of the present invention will be described. First, a press plate 14 having a flat surface 14a having a surface roughness Ra of 10 μm or more and 100 μm or less is mounted on the inclined surface 13a of the inclined table 13, and a glass substrate 16 is mounted thereon. Then, the press plates 14 and the glass substrates 16 are alternately stacked on the glass substrate 16, thereby stacking the press plates 14 and the glass substrates 16 in a plurality of stages. Then, a weight 18 is placed on the press plate 14 located at the top. Thereby, both surfaces of the glass substrate 16 are pressed by the flat surface 14a of a press plate.

  Further, when the press plate 14 and the glass substrate 16 are stacked, the press plate 14 and the glass substrate 16 may slip due to the air that enters between the press plate 14 and the glass substrate 16. At this time, when the press plate 14 and the glass substrate 16 are stacked on a flat surface, there is a possibility that the stacked ones due to slippage of the press plate 14 or the like may collapse. Even if air enters between the press plate 14 and the glass substrate 16 by stacking the glass substrate 16 on the inclined surface 13 a of the tilt base and supporting the side surface on the lower end side of the press plate 14 with the support rod 20. Since the plates 14 and the like do not slide, they can be reliably stacked.

  When the stacking of the press plate 14 and the glass substrate 16 is completed, the door 11a of the heating furnace is opened, and the inclined table 13 on which the press plate 14 and the glass substrate 16 are stacked is put into the heating furnace 11. When the tilt table 13 enters the heating furnace 11, the door 11a is closed, and the inside of the heating furnace 11 is gradually heated from room temperature to 500 ° C., and 500 ° C. is maintained for about 8 hours. Thereafter, it is gradually cooled to 100 ° C. in the heating furnace 11. Thereby, the annealing process is completed. The glass substrate 16 after the processing is flattened by removing distortions such as residual stress and warping of the surface. The glass substrate 16 after annealing is naturally cooled in the heating furnace 11 as it is. Note that the heating time and annealing time in the annealing process are measured with a timer switch.

  In this embodiment, both surfaces of the glass substrate are pressed with a press plate made of a quartz plate, but the surface roughness Ra has a flat surface of 10 μm or more and 100 μm or less, and the annealing point is more than the annealing point of the glass substrate. If it is a press plate made of a glass material that is 50 ° C. or higher, it may be pressed by other than the quartz plate. In addition, you may press with the thing which does not deform | transform at the temperature which anneals a glass substrate, for example, an iron plate, a ceramic, etc.

  Further, in the present embodiment, distortion of a thin glass substrate used for an incident angle limiting filter of a small image scanner is removed according to the present invention. However, the present invention is not limited to a plasma display panel (PDP) or a liquid crystal display device ( The distortion of the glass panel mounted on the LCD) can also be removed.

DESCRIPTION OF SYMBOLS 10 Glass substrate distortion removal apparatus 11 Heating furnace 13 Inclination stand 13a Inclined surface 14 Press plate 14a Flat surface 16 Glass substrate 20 Support rod

Claims (8)

By alternately superimposing a glass substrate and a press plate made of a glass material having an annealing point higher than the annealing point of the glass substrate by 50 ° C. or more and stacking a plurality of stages, both surfaces of the glass substrate are flattened on the press plate. Press on the surface,
A method for removing distortion of a glass substrate, comprising annealing the glass substrate whose both surfaces are pressed.   The press plate and the glass substrate are stacked obliquely on an inclined table having an inclined surface inclined at a constant angle, and a support rod attached to a side surface on the lower end side of the press plate in a direction orthogonal to the inclined surface. The weight removal method of the glass substrate according to claim 1, wherein a weight is placed on a press plate positioned at the top.   The method for removing distortion of a glass substrate according to claim 1, wherein the press plate is a quartz plate.   4. The method for removing strain from a glass substrate according to claim 1, wherein the flat surface has a surface roughness Ra of 10 [mu] m to 100 [mu] m. A plurality of press plates that are made of a glass material having an annealing point that is 50 ° C. higher than the annealing point of the glass substrate, and that presses both surfaces of the glass substrate with flat surfaces by alternately stacking and stacking with the glass substrate. When,
An apparatus for removing distortion of a glass substrate, comprising: annealing processing means for performing an annealing process on the glass substrate whose both surfaces are pressed. An inclined table in which the press plate and the glass substrate are obliquely stacked on an inclined surface inclined at a certain angle;
A support rod attached in a direction orthogonal to the inclined surface and supporting a side surface on the lower end side of the press plate;
6. The apparatus for removing distortion of a glass substrate according to claim 5, further comprising a weight placed on a press plate located at the top.   The glass substrate distortion removing apparatus according to claim 5 or 6, wherein the press plate is a quartz plate.   8. The glass substrate distortion removing apparatus according to claim 5, wherein the flat surface has a surface roughness Ra of 10 μm to 100 μm. 9.

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