JP4741280B2 - Manufacturing method of optical low-pass filter - Google Patents

Description

The present invention relates to a method for manufacturing an optical low-pass filter formed by bonding a quartz substrate and a glass substrate, and particularly relates to a method for manufacturing an optical filter with less man-hours and less occurrence of manufacturing defects such as chipping.

  The optical filter is provided in an imaging device such as a video camera or a digital still camera (DSC), and filters an optical pseudo signal included in a video signal imaged by a lens of the imaging device or a specific frequency component. For the purpose of attenuating the signal, the image pickup device is widely introduced from industrial image pickup devices to consumer and general use image pickup devices.

  For example, an optical low-pass filter that is one of the optical filters is a sampling of a CCD included in the received video when the received video obtained by the lens of the imaging device is converted into an electrical signal by a solid-state imaging device (hereinafter referred to as CCD). It is used to suppress the generation of moiré-like pseudo signals by attenuating high frequency components of half or more of the frequency before the received image reaches the CCD. Due to such a configuration, the optical low-pass filter is arranged between the lens and the CCD in the imaging apparatus.

  As one manufacturing method of such an optical low-pass filter, first, a quartz substrate 41 and a glass substrate 42 that have been polished to a desired thickness are prepared, and the quartz substrate 41 and the glass substrate 42 are bonded with an adhesive or the like. The optical low-pass filter substrate 40 is formed by bonding. Next, the optical low-pass filter substrate 40 is attached to the glass plate 44 with a water-soluble adhesive 43 or the like, and a straight blade is formed along a cutting line that divides each optical low-pass filter forming region set in the optical low-pass filter substrate 40. At 45, a cut portion reaching the plate glass 44 is formed and the optical low-pass filter substrate portion is cut, and then separated from the plate glass 44 to form individual optical low-pass filters. FIG. 4 is a schematic view showing a part of the above-described process using a cross-sectional view.

  As another manufacturing method, an optical low-pass filter substrate is formed and fixed on a plate glass, and a V-shaped groove is formed on a quartz substrate with a V-shaped processing blade. A manufacturing method including a step of cutting the inside of the V-shaped groove with a straight blade and dividing it into individual optical low-pass filters is used.

  In some cases, a lithium niobate substrate or the like is used instead of the quartz substrate. In order to give such an optical low-pass filter a function of blocking infrared rays, an optical cut-off film formed on the outermost surface of the optical low-pass filter is also used.

  The following documents are disclosed about the optical low-pass filter and the dicing method as described above.

JP 11-218612 A JP 9-326373 A

  In addition, the applicant did not find any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the prior art document information described above.

  In recent years, the resolution of image pickup apparatuses such as video cameras and DSCs has been remarkably increased, and accordingly, measures against foreign matters adhering to the surface of the optical low-pass filter have become essential.

  However, in an optical low-pass filter formed by a conventional manufacturing method, chipping easily occurs at the edges and corners when stress is applied from the outside during manufacturing or transportation, and the fragments are formed on the surface of the optical low-pass filter. There is a risk that it will adhere and reduce the product yield. In particular, if the optical low-pass filter substrate is cut at once with a straight blade, stress at the time of cutting is applied to the corners of the glass substrate having a hardness lower than that of the quartz substrate, and the glass substrate is cracked or chipped.

  Further, in the conventional method for manufacturing an optical low-pass filter as described above, it is not determined from which side of the crystal substrate or the glass substrate constituting the optical low-pass filter substrate. Therefore, when cutting from the glass substrate side having low hardness, the vibration of the blade cannot be suppressed, and chipping due to the vibration of the blade may occur. Further, when the optical low-pass filter substrate is cut, the tip of the straight blade enters the plate glass and an unnecessary groove is formed. As a result, the plate glass needs to be discarded for each cutting process, which is very uneconomical.

  Further, in the process of forming a V-shaped groove on the optical low-pass filter substrate with a V-shaped blade and then cutting the optical low-pass filter substrate by inserting a straight blade into the V-shaped groove, the center line of the tip of the V-shaped groove The center line of the straight blade must be matched and cut, which requires a precise and complicated manufacturing apparatus. Further, it is necessary to switch between the V-shaped processing blade and the straight blade depending on the process, which may cause an increase in man-hours.

The present invention has been made in view of the problems of the prior art, and includes an optical low-pass filter substrate obtained by bonding a quartz substrate having a plurality of optical low-pass filter formation regions and a glass substrate having the same area as the quartz substrate. In the method of manufacturing an optical low-pass filter, after forming, the optical low-pass filter substrate is cut along a cutting line that divides each optical low-pass filter forming region to obtain individual optical low-pass filters.
An optical low-pass filter substrate is formed by pasting one main surface of a crystal substrate on one main surface of a glass substrate, and the other main surface of the glass substrate constituting the optical low-pass filter substrate is attached to a dicing table via an adhesive tape. From the straight blade portion on the both side surfaces of the circular straight blade portion along the cutting line dividing each optical low-pass filter forming region on the other main surface of the quartz substrate The V-shaped machining blade portion having a small diameter and having a predetermined taper angle from the fixed surface to the straight blade portion toward the exposed surface opposite to the fixed surface, and the surface diameter gradually decreases. A dicing blade that is fixed concentrically with the straight blade and that can be attached and detached from the straight blade. The step of forming the V-shaped groove and the cut portion to a predetermined depth and the optical low-pass filter substrate on which the desired V-shaped groove and the cut portion are formed are peeled off from the adhesive tape, the optical low-pass filter substrate is inverted, and the quartz substrate A process of attaching the other main surface to the adhesive tape and fixing the optical low-pass filter substrate on the dicing table, and a cutting line dividing each optical low-pass filter forming region on the other main surface of the glass substrate And a step of forming a V-shaped groove reaching the notch with a V-shaped processing blade and cutting the optical low-pass filter substrate into individual optical low-pass filters. .

  With such an optical low-pass filter manufacturing method, all corners formed by the cut surface and the substrate main surface can be chamfered. Therefore, when the optical low-pass filter substrate is cut, or when the optical low-pass filter substrate is cut into individual optical low-pass filters. When the filter is transported, since no stress is applied to the corner from the outside, the occurrence of chipping can be suppressed to a very low level.

  Further, in the manufacturing method of the present invention, since the glass substrate is not cut by the straight blade portion of the dicing blade, chipping is also possible because a sharp angle portion formed by the cut surface and the main surface of the substrate is not formed on the glass substrate having low hardness. Further, in the present invention, the vibration of the blade can be suppressed by forming the cut portion from the quartz substrate side having a high hardness among the quartz substrate and the glass substrate constituting the optical low-pass filter substrate. Further, the occurrence of chipping due to blade vibration can be suppressed to a low level. Further, since the glass plate is not used in the manufacturing method of the present invention, the glass plate is not discarded and is economical.

  Therefore, the dicing blade according to the present invention and the manufacturing method using the dicing blade have high production efficiency, and the surface of the optical low-pass filter has almost no foreign matter due to chipping, and the manufacturing yield is very good. There exists an effect which can provide an optical low-pass filter.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an appearance of a dicing blade according to the present invention, (a) is a side view seen from the direction of the rotation axis, and (b) is a cross section taken along the virtual cutting line A1-A2 described in (a). The figure is shown. FIG. 2 is a process diagram illustrating an outline of a method for manufacturing an optical low-pass filter using the dicing blade shown in FIG. FIG. 3 is a perspective view showing the form of the optical low-pass filter manufactured by the process disclosed in FIG. 1, 2, and 3, for clarity of explanation, a part of the structure is not shown, and some dimensions are exaggerated.

  That is, in FIG. 1, a straight blade portion 12 concentric with the rotating shaft 11 is fixed to a rotating shaft 11 connected to a dicing blade rotating mechanism of a dicing apparatus (not shown). On both side surfaces of the straight blade portion 12, the diameter is smaller than that of the straight blade portion 12, and the taper is approximately 45 ° from the close contact surface with the straight blade portion 12 toward the exposed surface opposite to the close contact surface. The dicing blade 10 is configured by the V-shaped machining blade portion 13 having an angle and a gradually decreasing surface diameter concentrically with the straight blade portion 12 and fixed to the straight blade portion 12 or the rotary shaft 11. ing. The dimensional difference between the diameter of the straight blade portion 12 and the contact surface diameter of the V-shaped processing blade portion 13 depends on the notch depth formation dimension derived from the thickness dimension of the optical low-pass filter substrate to be processed and the opening portion of the notch portion. It is determined by the depth dimension of the V-shaped groove to be formed.

  Further, the taper angle of the V-shaped processing blade portion 13 disclosed in FIG. 1 is approximately 45 °. However, the taper angle is arbitrarily determined depending on the thickness of the optical low-pass filter substrate for forming the V-shaped groove and the desired shape of the V-shaped groove. Can be determined. Further, the V-shaped machining blade portion 13 can be attached / detached arbitrarily from the straight blade portion 12 and the rotary shaft 11. This makes it possible to change the combination of the straight blade portion 12 and the V-shaped machining blade portion 13 that match the notch portion and V-groove portion to be formed as described above, and the processing in the straight blade portion 12 and the V-shaped machining blade portion 13. When the difference in the amount of wear of the blade caused by the difference in form occurs, replacement of each blade part is possible.

A method for manufacturing an optical low-pass filter using the dicing blade 10 will be described below with reference to FIG.
That is, in FIG. 2A, first, a flat plate having a plurality of optical low-pass filter forming regions on one main surface of a flat glass substrate 21 made of IR glass having a plurality of optical low-pass filter forming regions in a matrix. The optical low-pass filter substrate 20 is formed by pasting one main surface of the quartz substrate 22, and the other main surface of the glass substrate 21 constituting the optical low-pass filter substrate 20 is connected to the dicing table 24 via an adhesive tape 23. Secure on top. In addition to IR glass, borosilicate glass, white plate glass, or the like is used as the glass substrate. The glass substrate 21 and the quartz substrate 22 are adjusted in thickness by polishing so as to obtain desired optical characteristics in advance. The adhesive tape 23 is a UV curable adhesive tape.

  Next, in FIG. 2B, the other main surface of the crystal substrate 22 constituting the optical low-pass filter substrate 20 is shown in FIG. 1 along a grid-like cutting line dividing each optical low-pass filter forming region. The V-shaped groove 26a and the cut portion 28 are formed almost simultaneously with the disclosed dicing blade 10. The cutting edge of the V-shaped blade portion 13 of the dicing blade 10 is formed so as to have a taper angle of approximately 45 ° with respect to the side surface of the blade toward the tip portion, so that the V-shaped groove 26a having a desired depth can be formed. It is formed with. In addition, the notch 28 is formed when the V-shaped groove 26b is formed by the V-shaped processing blade 25 from the other main surface side of the glass substrate 21 in the process described later. It is formed to a depth that allows the tip of 28 to penetrate.

  Next, in FIG. 2C, the optical low-pass filter substrate 20 in which the desired V-shaped groove 26 a and the cut portion 28 are formed is cured by irradiating the adhesive tape 23 with ultraviolet rays (UV) to thereby cure the adhesive tape 23. The optical low-pass filter substrate 20 is turned upside down, the other main surface of the crystal substrate 22 constituting the optical low-pass filter substrate 20 is attached to a new adhesive tape 13, and the optical low-pass filter substrate 20 is again mounted on the dicing table 24. Secure to. In the adhesive tape 23 in this step, if the adhesive force to the dicing table 24 and the optical low-pass filter substrate 20 can be maintained, the adhesive tape 23 from the process disclosed in FIG. I do not care. If the adhesive strength decreases or disappears when the optical low-pass filter substrate 20 is peeled off from the adhesive tape 23, a new adhesive tape is used to attach the adhesive tape to the other main surface of the quartz substrate 22, and the optical low-pass filter The substrate 20 is fixed on the dicing table 24.

  Next, in FIG. 2D, a grid-like cutting line that divides each optical low-pass filter formation region similar to that set on the other main surface of the quartz substrate 22 on the other main surface of the glass substrate 21. A V-shaped groove 26b reaching the tip of the cut portion 28 is formed by the V-shaped processing blade 25 along the optical low-pass filter substrate 20 and individual optical low-pass filters 29 as shown in FIG. Divide into The formed optical low-pass filter 29 shown in FIG. 3 has a shape in which sharp corners formed by the front and back main surfaces and side surfaces are all chamfered, and chipping generated at the corners in the above process is Since it can be removed by forming the V-shaped grooves 26a and 26b and there is no corner portion, chipping caused by stress applied from the outside during conveyance is almost eliminated.

  In the above embodiment, an optical low-pass filter in which a quartz substrate and a glass substrate are laminated is described as an example. However, instead of quartz, a substrate made of another optical crystal such as lithium niobate is used. Also good. Furthermore, although the said Example illustrated the optical low-pass filter only of a quartz substrate and a glass substrate, in order to give such an optical low-pass filter the function to interrupt | block infrared rays, an infrared cut film is provided on the outermost surface of an optical low-pass filter. The present invention is also applicable to those formed.

FIG. 1 shows an appearance of a dicing blade according to the present invention, (a) is a side view seen from the direction of the rotation axis, and (b) is a cross section taken along the virtual cutting line A1-A2 described in (a). The figure is shown. FIG. 2 is a process diagram illustrating an outline of a method for manufacturing an optical low-pass filter using the dicing blade shown in FIG. FIG. 3 is a perspective view showing the form of the optical low-pass filter manufactured by the process disclosed in FIG. FIG. 4 is a schematic view showing a part of a manufacturing process of a conventional optical low-pass filter using a cross-sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Dicing blade 11 ... Rotating shaft 12 ... Straight blade part 13 ... V-shaped processing blade part 20 ... Optical low-pass filter substrate 21 ... Glass substrate 22 ... Quartz substrate 23. ..Adhesive tape 24 ... Dicing table 25 ... V-shaped processing blade 26a, 26b ... V-groove 28 ... Incision 29 ... Optical low-pass filter

Claims (1)

After forming a quartz substrate having a plurality of optical low-pass filter formation regions and an optical low-pass filter substrate obtained by bonding a glass substrate having the same area as the quartz substrate, the optical low-pass filter substrate is divided into each optical low-pass filter formation region. In the method of manufacturing an optical low-pass filter, the optical low-pass filter is obtained by cutting along a cutting line to be divided.
An optical low-pass filter substrate is formed by pasting one main surface of a crystal substrate on one main surface of a glass substrate, and the other main surface of the glass substrate constituting the optical low-pass filter substrate is diced through an adhesive tape. Fixing on the table,
On the other principal surface of the quartz substrate, along the cutting line that divides each optical low-pass filter forming region, on both sides of the circular straight blade, the diameter is smaller than that of the straight blade, and the straight A dicing blade in which a V-shaped machining blade having a surface diameter that gradually decreases at a predetermined taper angle from a fixed surface to the blade to an exposed surface opposite to the fixed surface is fixed concentrically with the straight blade Forming a V-shaped groove and a cut portion to a predetermined depth at
The optical low-pass filter substrate on which the desired V-shaped groove and cut portion are formed is peeled off from the adhesive tape, the optical low-pass filter substrate is inverted, and the other main surface of the crystal substrate is attached to the adhesive tape, Fixing the filter substrate on the dicing table;
On the other main surface of the glass substrate, a V-shaped groove reaching the cut portion is formed by a V-shaped processing blade along the cutting line dividing each optical low-pass filter forming region, and the optical low-pass filter Cutting the substrate into individual optical low-pass filters;
A method for manufacturing an optical low-pass filter, comprising:

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