HK1055347B - Disk substrate, molding apparatus for injection-molding it, and disk substrate pick-up robot - Google Patents

Description

Disk substrate, molding apparatus for injection molding the substrate, and disk substrate take-out robot

Technical Field

The invention relates to the following technical fields: a disc substrate to which audio, video and other various information and tracking servo signals are transferred at the time of injection molding; a molding device for injection molding the disk substrate; and a disk substrate take-out device for taking out the disk substrate from the molding device.

Background

Hitherto, optical recording media and magnetic recording media have been widely known as disc-shaped recording media such as CDs, CD-ROMs, DVDs, DVRs, MDs, etc., on which audio, video and other various information and servo signals, etc. can be recorded. These recording media include a phase-change type optical disc in which a laser beam is irradiated onto a synthetic resin disc substrate, signals such as an information signal and a tracking servo signal are written on this substrate in the form of pits and grooves (guide grooves), and the signals are read using a change in reflectivity due to a change in the crystal structure of a recording layer, an optical disc for reading the signals using the magneto-optical effect, and a magnetic disc for magnetically reading and writing the signals, and the like.

As a method of forming an information signal and a tracking servo signal and the like in the form of fine irregularities such as pits and grooves and the like in the recording layer of the disc substrate, a method of injection molding the disc substrate using a molding machine is now generally used.

Fig. 22 to 24 show a molding apparatus 51 of a convex gate cutting system using a fixed-side die according to the related art, in which a cavity 54 as a disk forming space is vertically formed between bonding faces of a fixed platen 52 and a movable platen 53. A stamper 55 is vertically arranged on the fixed platen 52 side of the cavity 54, and the inner circumference of the stamper 55 is fixed to the fixed mirror surface with a mechanical jig. A cylindrical injection port 56 is horizontally arranged in the fixed platen 52 at a central portion of the cavity 54, and a cylindrical bulging gate cutter (also referred to as a "punch"), a small-diameter ejector pin 58, and a cylindrical ejector 59 are horizontally arranged at a position opposite to the injection port 56. The ejector pin 58 is arranged at the center of the bulge-shaped gate cutter 57, and the ejector 59 is arranged at the outer circumference of the bulge-shaped gate cutter 57.

The injection hole 60 at the center of the injection port 56 is bored at a convex gate forming concave portion 61, wherein an injection cylinder (not shown) is connected to the injection port 56, the concave portion 61 is formed at the tip of the injection port 56, and the tip of the convex gate cutter 57 is formed at a convex gate forming convex portion 62. A convex-shaped gate 64 that is convex in shape with respect to the signal transmission side 63 is formed between the concave portion 61 and the convex portion 62, wherein the signal transmission side 63 is a surface on the stamper 55 side of the cavity 54. Therefore, the bulge gate cutter 57 is a bulge gate cutter for forming the bulge gate 64.

In the molding apparatus 51 of the protrusion-type gate system according to the related art, the molten resin P1 including plasticized polycarbonate or other synthetic resin is injected from the injection cylinder into the injection hole 60 in the direction of arrow a and is charged into the cavity 54 through the protrusion-type gate 64 under pressure, and under this condition, the fixed platen 52 and the movable platen 53 are heated. In this case, the molten resin P1 compressed to a high pressure by the shot sleeve is pressed onto the minute unevenness surface of the stamper 55, where the disc substrate 73, as shown in fig. 25, 26, is molded, in which the signals 71 such as the information signal and the tracking servo signal are transmitted to the signal transmission surface 72 in the form of pits and grooves or the like. Subsequently, the center hole 74 of the disk substrate 73 is formed by punching.

In this case, the precision condition of the signal 71 transmitted to the disk substrate 73 is mainly determined by the plastic molten resin temperature, the mold temperature, and the injection pressure of the injection cylinder, however, the warpage or the like of the disk substrate 73 thus injection-molded is determined by the mold temperature, the injection pressure, and the cooling time.

The formation of the center hole 74 of the injection-molded disc substrate 73 is generally performed during the cooling of the fixed and movable platens 52 and 53 while continuing to compress the molten resin P1 filled in the cavity 54.

To this end, a center hole 74 as a circular hole has been formed in the center of the disk substrate 73 by punching (referred to as "hole cutting") in a method in which the male gate cutter 57 is advanced in the arrow b direction from the retracted position shown in fig. 23 to the advanced position shown in fig. 24 so as to cut the incompletely solidified resin between the outer circumferential surface 62a of the male portion 62 of the male gate cutter 57 and the inner circumferential surface 61a of the female portion 61 of the injection port 56. At this time, a substantially T-shaped injection port and gate residual resin 73a remain in the injection hole 60, and the projection-shaped gate 64 is discharged from the signal transmission surface 72 of the disk substrate 73 toward the fixed platen 52 side in the arrow b direction.

As shown in fig. 25, in an optical disc having a diameter of 12cm, such as a CD, a CD-ROM, a DVD, or a DVR, the diameter of the center hole 74 is 15.0mm, whereas the diameter of the center hole 74 is 11.0mm in an MD or the like.

As shown in fig. 25, the center hole 74 thus formed is formed as a straight hole in which the hole diameter is parallel to the axial direction over the entire thickness of the disk substrate 73.

Although the time for punching the center hole 74 varies depending on the kind of synthetic resin or the like, punching is preferably performed with the lip gate cutter 57 before the molten resin P1 is completely solidified, and is generally considered to be preferably performed within about 2 seconds after the injection of the molten resin P1 is completed. When the punching time of the center hole 74 is delayed from the above time, strain due to punching and punching residues is easily generated on the inner circumference of the center hole 74, and a disc substrate 73 having abnormal birefringence may be molded, or a gate cutting stroke is changed, which results in a defective product.

However, before the molten resin P1 solidifies, that is, within 2 seconds after the molten resin P1 is injection-molded, when the center hole 74 is punched between the convex portion 62 of the convex-shaped gate 57 and the concave portion 61 of the injection port 56, the resin P1 before solidifying flies into the gap between the outer circumferential surface 62a of the convex portion 62 and the inner circumferential surface 61a of the concave portion 61, which inevitably generates a burr 75 in a shape convex outward from the edge on the signal transmission surface 72 side of the center hole 74, as shown in fig. 25. The height H1 of flash 75 varies depending on the molding conditions (temperature of resin P2 in the gate, etc.) of the gap between concave portion 61 and convex portion 62, as shown in fig. 22 and 23; the height H1 has hitherto been several tens of μm, up to 100. mu.m.

The disk substrate 73 shown in fig. 26 is a substrate obtained by injection molding using a molding apparatus of a movable-side die of the related art and punching a center hole 74 from the signal transfer surface 72 side to the opposite side. In this case, flash 75 is generated in a shape protruding outward from the surface of the center hole 74 opposite to the signal transfer surface 72, and the height H1 of the flash 75 is equal to that shown in fig. 25.

Fig. 27 shows a conventional disk substrate take-out robot 81, and the robot 81 takes out the disk substrate 73 injection-molded by the molding device 51 from the molding device 51 and transfers it to a aligner (not shown).

That is, here, the disc substrate 73 is injection-molded by using the molding apparatus 51 of the projected gate cutting system of the conventional fixed-side die shown in fig. 22; the punching of the center hole 74 is performed by pushing the projection-shaped gate cutter 57 from the movable platen 53 side toward the fixed platen 52 in the arrow b direction, as described in connection with fig. 24. In the case of taking out the injection-molded disc substrate 73 from the molding apparatus 51, the movable platen 53 is opened (spaced) from the fixed platen 52 in the arrow a direction in fig. 22, and, as shown in fig. 27, the disc substrate 73 and the injection port and gate residual resin 73a are separated from each other so that the disc substrate 73 remains on the arrow a direction side and the injection port and gate residual resin 73a remains on the arrow b direction side, which is the movable platen 53 side and the arrow b direction side is the fixed platen 52 side, at which time the injection port and gate residual resin 73a and the disc substrate 73 are peeled off from the movable platen 53 in the arrow b direction in fig. 22 by the ejector 58 and ejector 59 or the like.

In fig. 27, first, the robot 81 grips the outer circumferential portion of the center hole 74 of the disk substrate 73 by sucking from the signal transmission surface 72 side with the vacuum pad 82, wherein the disk substrate 73 is peeled off from the movable platen 53 in the arrow b direction by means of the ejector 59; and the robot 81 receives the disk substrate 73 in the arrow b direction in such a manner as to separate the disk substrate 73 from the movable platen 53. At the same time, the inlet and gate residual resin 73a discharged by the ejector 58 in the arrow b direction is gripped by the robot arm 81, and the disk substrate 73 and the inlet and gate residual resin 73a are taken out from between the fixed platen 52 and the movable platen 53.

Next, the disk substrate 73 is transferred to the aligner by the robot arm 81 and aligned by fitting the center hole 74 of the disk substrate 73 to a disk receiving arm (not shown) of the aligner from the side of a reference surface 76 (described below) opposite to the signal transfer surface 72. After the disk substrate 73 is transferred to the aligner, the sprue and gate residual resin 73a is removed from the robot 81 by natural falling or blowing with air.

Then, the disk substrate 73 injection-molded as described above and shown in fig. 25 and 26 is laminated (coated) with a plurality of layers in the order of the recording layer, the reflective layer, and the protective layer on the signal transfer surface 72, thereby completing an optical disk 77 such as a CD and a DVD in which the signal 71 has been transferred onto the signal transfer surface 72.

In an optical disk drive on which an optical disk 77 or the like is used, a laser beam is incident from a reference surface 76 opposite to the signal transfer surface 72, where information reading and writing are performed. According to the specification, the reference surface 76 as a laser beam incident surface becomes a reference surface in the height direction, the center positioning pin of the spindle motor for driving the disk is inserted into the center hole 74 from the reference surface 76 side, and is centered by the edge 74b on the reference surface 76 side opposite to the signal transfer surface 72 of the center hole 74. Therefore, as shown in fig. 25, although the disk substrate 73 in which the burr 75 is generated on the signal transfer surface 72 side can be centered without the adverse effect of the burr 75, as shown in fig. 26, the disk substrate 73 in which the burr 75 is generated on the reference surface 76 side cannot be centered with high accuracy.

In an optical disc drive, in order to write and read information by focusing and reflecting a laser beam on a signal 71 made of minute unevenness, a high-precision servo mechanism is used. However, the servo performance of the servo mechanism has limitations, and in particular, it is important to limit the eccentricity of the helical groove and the central bore 74. In recent years, with an increase in recording density, the allowable value of eccentricity of the grooves and the center hole 74 is reduced to 100 μm in the case of CD and 60 μm in the case of DVD.

On the other hand, an increase in recording density is achieved mainly by reducing the wavelength of the laser beam and increasing the NA of the focusing lens (objective lens) (increasing the lens magnification). In the most common CD case, a laser with a wavelength of 780nm and a 0.45NA focusing lens are used; in the case of DVD, a laser having a wavelength of 630nm and a 0.6NA focusing lens are used. As the focusing lens NA is increased, the thickness of the disc substrate 73 as a laser beam transmitting layer is gradually reduced to reduce the run-length difference effect. The disc substrate 73 having a thickness of 1.2mm is used in the case of CD and the disc substrate 73 having a thickness of 0.6mm is used in the case of DVD, and thus it is advantageous to solve the curvature of the optical disc.

In recent years, in order to try to further increase the recording density, it has been proposed to use a laser light of a wavelength of 400nm and a focusing lens of 0.85 NA. Here, with the NA-enhanced focusing lens, it is necessary to reduce the thickness of the disk substrate 73 to about 0.1 mm; however, it is difficult to mold an ultra-thin disk substrate 73 satisfying the curvature and birefringence requirements in general injection molding.

In view of the above, these problems have been solved by laminating a reflection layer, a dielectric layer, a recording layer and a dielectric layer in the reverse order to the conventional order on the signal transmission surface 72 of the disk substrate 73, wherein the signal 71 composed of minute irregularities has been transmitted onto the signal transmission surface 72 in a conventional manner, and finally a light transmission layer of 0.1mm thickness is formed.

In this case, however, the reference surface is located on the opposite side as compared with the conventional disk substrate 73, and as shown in fig. 25 and 26, a tapered center positioning pin 79 of a disk holder 78 in a spindle motor for driving a disk is inserted into the center hole 74 from the signal transmission surface 72 side and caught and centered with an edge 74a on the signal transmission surface 72 side of the center hole 74.

In this case, the disk substrate 73 shown in fig. 26 is free from the burr 75 at the edge 74a on the signal transmission surface 72 side of the center hole 74, so that centering can be performed with high accuracy. On the other hand, the disk substrate 73 in which the burr 75 is generated at the edge 74a on the signal transmission surface 72 side of the center hole 74 shown in fig. 25 cannot be centered with high accuracy.

In addition, since the disk substrate 73 of this system has a very small eccentricity tolerance, it is fatal to generate the flash 75 on the signal transmission surface 72 side of the center hole 74 shown in fig. 25.

Although the flash 75 can be removed by cutting with a reamer or the like, waste is generated and the number of processes is increased when the flash 75 is removed, which inevitably leads to a reduction in yield and an increase in cost.

In order to restrict the generation of the burr 75 on the signal transfer surface 72, the stamper 55 fitted to the mold is arranged not on the fixed platen 52 side but on the movable platen 53 side (this method is referred to as "movable-side stamper"). Although it is certainly possible to avoid the generation of the flash 75 on the signal transfer surface 72 with this method, the movable-side die has such a structure that the shapes of the transferred pits and grooves are easily asymmetric. The reason is as follows. In this method, at the time of molding, after cooling is completed, the movable platen 53 is opened while keeping the disk substrate 73 adsorbed to the movable platen 53 side, and the disk substrate 73 is taken out in such a manner that the stamper 55 and the disk substrate 73 are peeled off by the ejector 59 and air. However, after the movable platen 53 is opened, the disk substrate 73 is rapidly cooled and contracted. But the pits and grooves are deformed because the stamper 55 shrinks less compared to the disk substrate 73. As the recording density of the disk increases, the precision required for the fine roughness shape increases, and therefore, it is difficult to mold the disk substrate 73 even with the movable-side stamper.

Even if the disc substrate to which the fine roughness without deformation has been transferred can be molded with the movable-side stamper under substantially non-shrinking material and molding conditions, it is impossible to avoid the generation of the flash 75 on the side of the surface 76 opposite to the signal transfer surface 72. Although the burr 75 does not have a bad influence on the eccentricity of the disk when the disk is stuck, the peeling of the burr 75 in production generates waste, and the burr adheres to the disk substrate 73, thereby increasing an error, resulting in a decrease in yield.

Disclosure of Invention

The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to provide a disk substrate having no flash on the edge of a central hole, a molding apparatus for optimally injection-molding the disk substrate, and a disk discharge apparatus for optimally taking out the disk substrate from the molding apparatus.

To achieve the above objects, the present invention also provides a disk substrate in which a signal is transferred to the substrate by injection molding, the disk substrate including a central hole; and an edge having a flash at least on a signal transfer surface side of the center hole, wherein a flash height is reduced to zero or limited to 10 μm or less, wherein at least the edge of the center hole is provided with an R surface or a C surface on a signal transfer surface side, and the disc substrate further comprises: a linear portion having an aperture in the same direction as the axial direction, the linear portion being provided on a side of the center hole opposite to the signal transmission surface side; and a tapered portion whose aperture gradually enlarges toward the signal transfer surface, the tapered portion being provided between the linear portion of the center hole and the signal transfer surface.

The present invention also provides a molding apparatus for injection-molding a disk substrate, which includes a cavity into which a molten resin is injected through an injection port and a recessed gate, and a signal transfer stamper disposed on a stationary platen side of the cavity, the molding apparatus including: a convex portion for molding the recessed gate disposed at a tip end of the sprue; a concave portion for molding the recessed gate, the concave portion being arranged on a tip end of a recessed gate cutter arranged on a movable platen side opposite to the convex portion; and a center hole molding part provided on an outer circumference of the injection port, wherein the center hole molding part includes: a first R-surface molding part or a first C-surface molding part for molding a first R-surface or a first C-surface at an edge on a signal transmission surface side of a center hole of the injection-molded disc substrate within the cavity, and wherein the center hole molding part includes: a straight-line molding portion for molding a straight-line portion having an aperture direction equal to an axial direction on a side of the center hole of the injection-molded disc substrate opposite to a signal transmission surface side within the cavity; and a tapered molding portion for molding a tapered portion whose aperture gradually expands toward the signal transfer surface side between the straight portion of the center hole of the injection-molded disc substrate and the signal transfer surface in the cavity.

The forward amount of the recessed gate cutter is not less than the thickness of the recessed gate and not more than the thickness of the recessed gate plus 0.5 mm.

The position at which the recessed gate is cut by the recessed gate cutter is set at a position equal to the aperture diameter of the linear portion of the center hole.

The recessed gate cutter includes a second R-surface molding portion or a second C-surface molding portion on a tip end of an outer circumferential portion of the recessed portion for molding a second R-surface or a second C-surface at an edge on a side of the center hole opposite to a signal transmission surface side.

The position of the recessed gate cut by a recessed gate cutter is set at a first position equal to the hole diameter of the linear portion of the center hole and a second position located within the first position and having a smaller diameter than the first position.

The present invention also provides a disk substrate take-out apparatus, comprising: a molding apparatus comprising a cavity provided between a fixed platen and a movable platen, a signal transmission stamper disposed on a side of the fixed platen of the cavity, and a recessed gate cutter disposed on a side of the movable platen, wherein a molten resin is injected into the cavity through an injection port and a recessed gate to mold a disk substrate; and, gate cutting is performed from the movable platen side with the recessed gate cutter; and a robot for taking out the disk substrate from the movable platen, wherein the disk substrate is released from the fixed platen together with the movable platen by opening the movable platen after injection molding, the robot comprising: means for discharging a sprue and gate residual resin to a side of said movable platen opposite to said disc substrate, wherein said center hole molding portion comprises: a first R-surface molding part or a first C-surface molding part for molding a first R-surface or a first C-surface at an edge on a signal transmission surface side of a center hole of the injection-molded disc substrate within the cavity, and wherein the center hole molding part includes: a straight-line molding portion for molding a straight-line portion having an aperture direction equal to an axial direction on a side of the center hole of the injection-molded disc substrate opposite to a signal transmission surface side within the cavity; and a tapered molding portion for molding a tapered portion whose aperture gradually expands toward the signal transfer surface side between the straight portion of the center hole of the injection-molded disc substrate and the signal transfer surface in the cavity.

The discharge device is provided with an air nozzle.

The disk substrate of the present invention constructed as described above is completely free of burrs at least at the edge on the signal transmission surface side of the center hole, or even if burrs are generated at this point, the height of the burrs can be limited to 10 μm or less, and thus the disk substrate can be centered with high accuracy by the center positioning pin of the spindle motor.

In addition, since the first R surface or the first C surface is formed at least on the edge of the center hole, the edge is completely free of flash.

In addition, the central hole includes: a linear portion having an aperture direction equal to the axial direction, the linear portion being provided on a side of the central hole opposite to the signal transmission surface side; and a tapered portion whose aperture gradually enlarges toward the signal transmission surface side, the tapered portion being provided between the linear portion of the center hole and the signal transmission surface. Therefore, when the mold is opened after the resin in the cavity is completely cooled and the disk substrate is peeled off from the stamper placed on the side of the fixed platen, the mold is more easily released.

The molding apparatus of the present invention constituted as described above is a molding apparatus for molding a disk substrate, said molding apparatus comprising: a cavity into which a molten resin is injected through an injection port and a recessed gate, and a signal transmission stamper disposed on a fixed platen side of the cavity, and the molding apparatus has a recessed gate cutting structure including: a recessed gate forming protrusion portion provided at a top end of the injection port; a recessed gate forming recessed portion provided on a tip end of a recessed gate cutter provided on a side of the movable platen opposite to the projecting portion; and a center hole molding part provided on an outer circumference of the sprue. Therefore, when the disk substrate is injection molded, the center hole is simultaneously injection molded with the center hole molding portion. Thus, even when the gate is cut by pushing a recessed gate cutter having a concave tip from the movable platen side, it is possible to produce a center hole whose both edges do not contain flash.

In addition, the center hole molding portion is provided with a first R surface molding portion or a first C surface molding portion for molding a first R surface or a first C surface at an edge on the signal transmitting surface side of the center hole. Therefore, when the disk substrate is injection-molded, the edge on the signal transmission surface side of the center hole can be simultaneously injection-molded into the R surface or the C surface.

Besides, the central hole molding portion is provided with a linear molding portion for molding a linear portion having an aperture direction equal to the axial direction on the side of the central hole opposite to the signal transmission surface side; and, the central hole molding portion is provided with a tapered molding portion for molding a tapered portion whose hole diameter gradually increases from the linear portion of the central hole toward the signal transfer surface side. Thus, when the disk substrate is injection-molded, the straight portion and the tapered portion can be simultaneously injection-molded with respect to the central hole.

In addition, the advance amount of the recessed gate cutter is set to be equal to or greater than the thickness of the recessed gate and equal to or less than the thickness of the recessed gate +0.5 mm. Therefore, the gate can be cut safely.

In addition to this, the position of cutting the recessed gate by the recessed gate cutter is set at a position equal to the aperture of the straight portion of the center hole of the disk substrate. Therefore, when the recessed gate is cut, no flash or the like is generated in the linear portion of the center hole of the disk substrate.

In addition, the recessed gate cutting machine provides a second R-surface molding portion or a second C-surface molding portion on an outer circumferential portion tip of the recessed gate forming recessed portion for molding a second R-surface or a second C-surface at an edge on a side of the center hole opposite to the signal transfer surface. Therefore, the second R surface or the second C surface may be molded at the edge on the opposite side of the central hole of the disk substrate from the signal transfer surface.

In addition, the position of the recessed gate cut by the recessed gate cutter is set at a first position equal to the hole diameter of the linear portion of the center hole of the disk substrate and at a second position located within the first position and having a smaller diameter than the first position. Therefore, the outside diameters of the sprue cut by the recessed gate cutter and the gate residual resin can be made smaller than the inside diameter of the sprue.

Further, the disk substrate take-out apparatus of the present invention constituted as described above is constructed such that: the gate cutting is performed from the movable platen side with a recessed gate cutter, and a robot for taking out the disk substrate from the movable platen has a device for discharging the sprue and gate residual resin to the movable platen side with respect to the disk substrate, wherein the disk substrate is peeled off together with the movable platen from the fixed platen by opening the movable platen after the injection molding. Therefore, it is possible to provide a disk substrate take-out apparatus optimally applied to a molding apparatus of a recessed gate cutting structure.

In addition to this, when the device for discharging the sprue and gate residual resin is provided with an air nozzle, the sprue and gate residual resin can be discharged onto the movable platen side safely and instantaneously.

Drawings

Fig. 1 is a sectional view showing a central hole portion of a disk substrate according to an embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view of the central bore of fig. 1.

Fig. 3 is an enlarged sectional view of a portion a of the recessed gate portion of the molding apparatus according to the first embodiment of the present invention in fig. 5.

Fig. 4 is a sectional view illustrating cutting of the recessed gate of fig. 3.

Fig. 5 is a sectional view of the entirety of a recessed gate portion of a molding apparatus according to a first embodiment of the present invention.

Fig. 6 is a sectional view showing the entirety of a molding apparatus of a fixed-side die and a recessed gate cutting system according to a first embodiment of the present invention.

Fig. 7 is a sectional view in a state where a molten resin is injected into the molding apparatus of fig. 6.

Fig. 8 is a cross-sectional view showing a recessed gate of the molding apparatus of fig. 7 being cut.

Fig. 9 is a sectional view when the molding apparatus of fig. 8 is opened.

Fig. 10 is a cross-sectional view of the disk substrate as it is peeled off the movable platen of the molding apparatus of fig. 9.

Fig. 11 is a sectional view showing a state where the disk substrate of fig. 10 is chucked by a robot of the disk discharging apparatus.

Fig. 12 is a sectional view showing an operation of discharging the sprue and the gate residual resin with the robot of fig. 11.

FIG. 13 shows the results of comparing the eccentricity amounts of the disk substrate, the movable side stamper substrate, the fixed side stamper substrate and the disk substrate removed by the reamer of the present invention.

Fig. 14 is a sectional view showing a main part of a molding apparatus according to a second embodiment of the present invention.

Fig. 15 is a sectional view showing cutting of the recessed gate of fig. 14.

Fig. 16 is a sectional view showing a main part of a molding apparatus according to a third embodiment of the present invention.

Fig. 17 is a sectional view showing cutting of the recessed gate of fig. 16.

Fig. 18 is a sectional view showing a main part of a molding apparatus according to a fourth embodiment of the present invention.

Fig. 19 is a sectional view showing cutting of the recessed gate of fig. 18.

Fig. 20 is a sectional view showing a main part of a molding apparatus according to a fifth embodiment of the present invention.

Fig. 21 is a sectional view showing the recessed gate of fig. 20 cut.

Fig. 22 is a sectional view showing a molding apparatus of a fixed-side stamper according to the related art.

Fig. 23 is an enlarged cross-sectional view of a recessed gate of the molding apparatus of fig. 22.

Fig. 24 is a sectional view showing a cutting manner of the recessed gate of fig. 23.

Fig. 25 is a sectional view of a central hole portion of a disc substrate injection-molded by a molding apparatus of a fixed-side stamper type according to the related art.

Fig. 26 is a sectional view of a central hole portion of a disc substrate injection-molded by a molding apparatus of a movable-side stamper type according to the related art.

Fig. 27 is a sectional view showing a disk substrate take-out robot according to the prior art.

Detailed Description

A disk substrate, a molding apparatus for injection molding the substrate, and a disk substrate take-out robot according to the present invention will now be described in the following order with reference to fig. 1 to 21.

(1) Disc substrate description (FIGS. 1 and 2)

(2) Description of a first embodiment of a molding apparatus for injection molding a disk substrate (FIGS. 3-10)

(3) Description of disk substrate taking-out apparatus (FIGS. 11-11)

(4) Description of measurement results of eccentricity of disc substrate (FIG. 13)

(5) Description of a second embodiment of a molding apparatus for injection molding a disk substrate (FIGS. 14 and 15)

(6) Description of a third embodiment of a molding apparatus for injection molding a disk substrate (FIGS. 16 and 17)

(7) Description of a fourth embodiment of a molding apparatus for injection molding a disk substrate (FIGS. 18 and 19)

(8) Description of a fifth embodiment of a molding apparatus for injection molding a disk substrate (FIGS. 20 and 21)

(1) Disc substrate description (FIGS. 1 and 2)

First, with reference to fig. 1 and 2, a disc substrate 23 into which a motor center positioning pin is inserted from the signal transmission surface side is described, wherein the disc substrate 23 is applied to an optical disc such as a DVR. The disc substrate 23 including the signal transfer surface 22 is provided with a center hole 24 injection-molded simultaneously with the injection molding of the disc substrate 23, as will be described later, in which signals 21 representing audio, video or other various information signals and servo signals, etc., have been transferred onto the signal transfer surface 22 in the form of minute irregularities such as pits and grooves in the same manner as in the prior art, as will be described later.

A straight portion 24a having an aperture Φ 1 parallel to the axial direction is formed on the side of a surface 25 of the injection-molding center hole 24 opposite to the signal transfer surface 22; a tapered portion 24b whose aperture Φ 2 gradually enlarges toward the signal transfer surface 22 is formed between the linear portion 24a of the center hole 24 and the signal transfer surface 22; an edge on the signal transfer surface 22 side of the tapered portion 24b is formed as a first R surface (or a first C surface) 24C. As required, a second R surface (or a second C surface) 24d may be formed at an edge on the side of the center hole 24 opposite to the signal transfer surface 22 side.

For example, in the case where the diameter of the disk substrate 23 such as DVR is 12cm, the aperture φ 1 of the linear portion 24a is set to 15.05 mm. In addition, the maximum aperture Φ 2 of the tapered portion 24b was set to 15.09mm, and the difference between the minimum aperture and the maximum aperture at the tapered portion 24b was set to about 0.02 mm. The depth D of the linear portion 24a is set to 0.3 mm.

Since the center hole 24 is injection-molded and the first R surface (or the first C surface) 24C is injection-molded at the edge on the signal transfer surface 22 side of the center hole 24, the edge on the signal transfer surface 22 side of the center hole 24 is naturally free of any flash.

As will be described later, when the second R surface (or the second C surface) 24d is injection-molded at the edge on the side of the surface 25 of the center hole 24 opposite to the signal transfer surface 22, the edge on the side of the center hole 24 opposite to the signal transfer surface 22 is also free from flash.

As shown in fig. 1, according to this disk substrate 23, a tapered center positioning pin 27 of a disk frame 26 of a spindle motor for driving a disk is inserted into the center hole 24 from the side of the signal transfer surface 22 as a reference surface, thereby chucking the disk substrate 23. Therefore, since the first R surface (or the first C surface) 24C does not contain the flash, the center hole 24 can be centered with high accuracy, and the eccentricity amount of the disk substrate 23 can be restricted to be extremely small.

As shown by the dotted line in fig. 1, the signal 21 portion of the disk substrate 23 will be coated later with a light transmitting layer 21a having a thickness of about 0.1 mm.

(2) Description of a first embodiment of a molding apparatus for injection molding a disk substrate (FIGS. 3-10)

A first embodiment of a molding apparatus 1 optimized for injection molding of the above-described disk substrate 23 is described below with reference to fig. 3 to 10. The molding apparatus 1 is a molding apparatus 1 of a recessed gate cutting system using a fixed-side die, in which a cavity 4 as a disk-shaped space is vertically formed between bonding surfaces of a fixed platen 2 and a movable platen 3. A stamper 5 is vertically arranged on the fixed platen 2 side of the cavity 4, and the inner circumference of the stamper 5 is fixed to the fixed mirror surface by a mechanical jig. A cylindrical sprue 6 is horizontally placed in the stationary platen 1 at the central portion of the cavity 4, and a cylindrical recessed gate cutter (also referred to as a "punch") 7, a small-diameter ejector pin 8, and a cylindrical ejector 9 are horizontally arranged at a position opposite to the sprue 6. The ejector pin 8 is disposed in the center of the recessed gate cutter 7, and the ejector 9 is disposed in the outer circumference of the recessed gate cutter 7.

An injection hole 10 is formed in the center of the injection port 6, wherein a shot sleeve (not shown) is connected to the injection port 6, and a recessed gate forming protrusion 11 is formed at the tip of the injection port 6. A recessed gate forming recessed portion 12 is formed at the tip of the recessed gate cutter 7. A recessed gate 14 is formed between the recessed gate forming convex portion 11 and the recessed gate forming concave portion 12, the recessed gate 14 being formed in a concave form with respect to a signal transmission surface 13, wherein the signal transmission surface 13 is a surface on the side of the stamper 5. Therefore, the recessed gate cutter 7 is a gate cutter having a recessed shape for forming the recessed gate 14. The thickness W of the recessed gate 14 was 0.3mm, and the projection amount P1 of the recessed gate cutter 7 was 0.4 mm. At the time of cutting the recessed gate, a biting amount (overlapping amount) P2 of the peripheral portion tip 7a of the recessed gate cutter 7 with respect to the injection port 6 is set to about 0.1mm as will be described later.

A center hole molding portion 15 for injection molding a center hole 24 of the disk substrate 23 shown in fig. 1 and 2 is provided on the outer circumference of the recessed gate forming projecting portion 11 of the molding apparatus 1.

That is, as shown in fig. 3 to 5, the linear molding portion 16 for molding the center hole 24a, the tapered molding portion 17 for molding the tapered portion 24b, and the first R surface (or first C surface) molding portion 18 for molding the first R surface (or first C surface) 24C are provided on the outer circumference of the recessed gate forming bulging portion 11.

As shown in fig. 8, an auxiliary ejector 19 having an advancing amount of about 0.2mm is secondarily fitted on the outer circumference of the tip of the injection port 6 of the fixed platen 2. The auxiliary ejector 19 is propelled with no-flow air.

Subsequently, the injection molding of the disk substrate 3 by the molding apparatus 1 of the recessed gate system is described. First, as shown in fig. 3 to 7, under the heating of the fixed platen 2 and the movable platen 3, a moldable molten resin P1 composed of polycarbonate or other synthetic resin is injected from the injection cylinder into the injection hole 10 in the direction of arrow a and is pressed under pressure into the cavity 4 through the recessed gate 14. In this case, during or after the charging of the molten resin P1, the movable platen 3 is pressed against the fixed platen 2 side at a high pressure by means of a pressure cylinder disposed on the back surface of the movable platen 3. The molten resin P1 compressed by high pressure in the cavity 4 is pressed against the minute unevenness surface of the stamper 5, whereby the disk substrate 23 is injection-molded in which the signals 2 such as the information signal and the tracking servo signal have been transferred to the signal transfer surface 22 in the form of pits and grooves or the like, as shown in fig. 1 and 2.

In addition to this, at the time of injection molding of the disk substrate 23, the linear portion 24a, the tapered portion 24b and the first R surface (or first C surface) 24C of the center hole 24 are simultaneously molded by the linear molding portion 16, the tapered molding portion 17 and the first R surface (or first C surface) molding portion 18 in the center hole molding portion 15 located on the outer circumference of the recessed gate forming protrusion portion 11.

Next, as shown in fig. 4 and 8, the recessed gate cutter 7 is advanced (advanced) in the b direction by an advanced amount P1 of 0.4mm as shown in fig. 3, whereby gate cutting is performed by 0.3mm between the inner circumferential surface 7b of the tip of the outer circumferential portion 7a of the recessed gate 14 of the recessed gate cutter 7 and the linear molding portion 16, which linear molding portion 16 is the outer circumferential surface of the recessed gate-forming bulging portion 11 of the sprue 6.

Next, after the fixed platen 2 and the movable platen 3 are cooled for about 10 seconds, the pressure of the shot sleeve is lowered; then, as shown in fig. 9, air is blown in the arrow a direction from the outer circumferential portion of the injection port 6 of the fixed platen 2, and the auxiliary ejector 19 is secondarily pushed in the arrow a direction, so that the movable platen 3 is sufficiently opened in the arrow a direction. By doing so, the injection-molded disc substrate 23 in a state of being adsorbed to the movable platen 3 is pulled away from the stamper 5 of the fixed platen 2 in the arrow a direction, and the injection-port and gate-remaining resin 23a that has remained in the injection port 10 and the recessed gate 14 is also pulled away from the injection port 6 in the arrow a direction. Subsequently, as shown in fig. 10, the ejector 9 of the movable platen 3 advances in the arrow b direction, and thereby the injection-molded disc substrate 23 peels off from the movable mirror surface of the movable platen 3 in the arrow b direction. At the same time, the sprue and the sprue residual resin 23a are also peeled off by the carrier rod 8 in the arrow b direction.

Finally, as shown in fig. 11, the disk substrate 23 and the inlet and gate residual resin 23a are caught by the robot arm 32 of the disk substrate take-out apparatus 31 and taken out from the movable platen 3, and the disk substrate 23 is transferred to a aligner (not shown).

(3) Description of disk substrate taking-out apparatus

The disk substrate taking-out apparatus 31 is described below with reference to fig. 10 and 11. For the ejector device 31, a robot 32 of the related art is used.

First, when injection molding is performed by the above-described molding apparatus 1 of the cavity gate system and the movable platen 3 is opened as shown in fig. 10, the sprue and gate-remaining resin 23a is pushed from the center hole 24 of the disk substrate 23 onto the side of the surface 25 opposite to the signal transmission surface 22.

Therefore, as shown by the chain line in fig. 11, the suction cup 33 of the robot 32 is sucked to the signal transmission surface 22 side of the outer circumferential portion of the center hole 24 of the disk substrate 23, thereby chucking the disk substrate 23, then the disk substrate 23 is pulled away from the movable platen 3 together with the sprue and gate residual resin 23a, and then, in the same manner as in the prior art, when the sprue and gate residual resin 23a interferes with the opposite surface 25 of the disk substrate 23 on the portion of the center hole 24, the disk substrate 23 is transferred from the movable platen 3 in the arrow a direction, so that the disk substrate 23 cannot be transferred to an apparatus such as a aligner.

To solve this problem, as shown in fig. 11, in the disk substrate taking-out apparatus 31, an air nozzle 34 as a discharging device is fitted at a position opposite to the injection port and the gate residual resin 23a in the arrow a direction, and air is ejected from the air nozzle 34 in the arrow a direction, so that the injection port and the gate residual resin 23a can be easily discharged to the opposite surface 25 side through the center hole 24 of the disk substrate 23 in the arrow a direction.

Therefore, according to the disk substrate taking-out apparatus 31, when the movable platen 3 is opened, the injection port and gate residual resin 23a advances to the opposite surface 25 side of the disk substrate 23. Thus, although the position of the sprue and gate residual resin 23a with respect to the disk substrate 23 is opposite to that in the prior art shown in fig. 27, the sprue and gate residual resin 23a can be easily discharged in the arrow a direction without any trouble by ejecting air from the air nozzle 34 of the robot 32 immediately after the chuck 33 of the robot 32 catches the disk substrate 23 before the disk substrate 23 is transferred to the aligner (not shown) by the robot 32. Therefore, after the sprue and gate residual resin 23a are discharged, the disk substrate 23 can be smoothly transferred to a aligner (not shown) by the robot arm 32 for alignment in the same manner as in the prior art.

(4) Description of eccentricity measurement of disk substrate

The measurement result of the eccentricity amount of the disk substrate 23 is described below with reference to a table shown in fig. 13. Example 1 shows the results of 10 measurements of the eccentricity of a disk substrate 23 injection-molded by the molding apparatus 1 of the present invention. Comparative example 1 shows the results of 10 measurements of the eccentricity amount of the moving-side die substrate, which is a conventional disk substrate 73 injection-molded by a conventional molding apparatus in which a mold is placed on the movable platen side. Comparative example 2 shows the results of 10 measurements of the eccentricity amount of the fixed-side die substrate, in which the moving-side die substrate was a conventional disk substrate 73 injection-molded by a conventional molding apparatus 51, as shown in fig. 25, in which a die 55 was placed on the side of the fixed platen 52, as described in connection with fig. 22. Further, comparative example 3 shows the results of 10 measurements of the eccentricity of the fixed-side stamper substrate, from which flash 75 had been removed with a reamer in comparative example 2.

The eccentricity is measured by the following method: a center positioning pin of the spindle motor catches the disk substrate, the disk substrate is driven to rotate at a fixed speed while applying a focus servo to the spindle motor, and an eccentricity amount is calculated from the number of slots in an eccentric portion of the spiral slot.

As is apparent from the comparative data shown in the table of fig. 13, the eccentricity of the disk substrate 23 according to the present invention is 20-30 μm, which is the minimum. The movable-side stamper substrate shown in comparative example 1 had an eccentricity of 20 to 30 μm, which is equivalent to the eccentricity according to the present invention. However, as described above, in the case of the movable-side stamper substrate, the disk substrate is rapidly cooled after the mold is opened, and the pits and grooves are deformed, and thus, the obtained disk substrate is not suitable as a disk for high-density recording.

In the case of the conventional fixed-side stamper substrate as shown in comparative example 2, the eccentricity amount is widely dispersed in the range of 15 to 70 μm, which makes it impossible to establish a system having such a disk substrate because of the presence of the flash 75 as described above.

In the case of the fixed-side stamper substrate where the burr 75 was removed by a reamer as shown in comparative example 3, the eccentricity amount was as small as 20 to 30 μm. However, as described above, there are the following problems: waste generation and an increase in the number of processes result in a decrease in yield and an increase in cost.

(5) Description of a second embodiment of a molding apparatus for injection molding a disk substrate

A second embodiment of the molding apparatus 1 is described below with reference to fig. 14 and 15. In this case, a second R-surface molding portion (or a second C-surface molding portion) 20 is provided on a corner portion on the inner circumference side of the tip end surface of the outer circumferential portion 7a of the recessed gate forming recessed portion 12 of the recessed gate cutter 7.

As shown in fig. 14, a molten resin P1 is injected into the cavity 4 through the recessed gate 14, thereby molding the disk substrate 23. At the moment when the molten resin P1 solidifies to some extent (at the moment when the disk substrate 23 can be compressed), the recessed gate cutter 7 advances in the arrow b direction, cutting the gate by 0.3mm, as shown in fig. 15. At the time of gate cutting, an edge portion on the opposite side of the center hole 24 of the disk substrate 23 from the signal transfer surface 13 side molds a second R surface (or a second C surface) 24d with a second R surface molding portion (or a second C surface molding portion) 20.

(6) Description of a third embodiment of a molding apparatus for injection molding a disk substrate

A third embodiment of the molding apparatus 1 is described below with reference to fig. 16 and 17. In this case, the cutting positions are provided at two inner and outer positions, namely: a first cutting position C1 for cutting by the outer circumferential surface 7C of the outer circumferential portion 7a of the recessed gate forming recessed portion 12 of the recessed gate cutter 7 and the straight molding portion 16 as the outer circumferential surface of the recessed gate forming projecting portion 11 of the injection port 6; and a second cutting position C2 for cutting by the inner circumferential portion 7b of the outer circumferential portion 7a of the recessed gate-forming concave portion 12 and the inner circumferential surface 11b of the cut-away portion 11a formed annularly on the outer circumferential portion of the tip of the recessed gate-forming convex portion 11. The inside diameter φ 1 of the first cutting position C1 is equal to the inside diameter φ 1 of the linear portion 24a of the center hole 24 of the disk substrate 23, and the inside diameter φ 3 of the second cutting position C2 is smaller than the first inside diameter φ 1(φ 1 > φ 3), with a concentric relationship therebetween.

In this case, as shown in fig. 16, a molten resin P1 is injected into the cavity 4 through the recessed gate 14, thereby molding the disk substrate 23. At the moment when the molten resin P1 solidifies to some extent (at the moment when the disk substrate 23 can be compressed), the recessed gate cutter 7 advances in the arrow b direction, cutting the gate. At the time of gate cutting, the first cutting position C1 of the disk substrate 23 is cut between the outer circumferential surface 7C of the tip end portion 7a of the recessed gate cutter 7 and the linear molding portion 16 of the central hole molding portion; and the second cutting position C2 of the disk substrate 23 is cut between the inner circumferential surface 7b of the tip end portion 7a of the recessed gate cutter 7 and the inner circumferential surface 11b of the cut-away portion 11a of the recessed gate-forming projecting portion 11. Thus, the gate is cut simultaneously at two inner and outer cutting positions.

In this case, as shown in fig. 17, the maximum outer diameter Φ 3 of the injection port and the gate-remaining resin 23a cut from the gate of the disk substrate 23 is smaller than the minimum inner diameter Φ 1 of the center hole 24 of the disk substrate 23. Therefore, the following steps can be performed more smoothly: after the suction cups 33 of the robot 31 catch the molded disk substrate 23, the sprue and gate residual resin 23a are blown off from the inside of the center hole 24 of the disk substrate 23 in the arrow b direction by the air nozzles 34 as described above in connection with fig. 11. In addition, in this case, the sprue and gate residual resin 23a may be blown off from the inside of the center hole 24 of the disk substrate 23 in the direction of the arrow b shown by the broken line in fig. 11 in such a manner as to pass through the center hole 24, which is the opposite direction.

(7) Description of a fourth embodiment of a molding apparatus for injection molding a disk substrate

A fourth embodiment of the molding apparatus 1 is described below with reference to fig. 18 and 19. In this case, the diameter of the outer circumferential surface 7c of the tip portion 7a of the recessed gate cutter 7 in the third embodiment shown in fig. 16 and 17 is set sufficiently larger than the diameter of the linear molding portion 16 of the center hole molding portion 15, whereby a sufficiently large step H is formed between the outer circumferential surface 7c and the linear molding portion 16.

Therefore, in this case, as shown in fig. 18, the opening coefficient of the connecting portion 14a between the outer circumferential portion of the recessed gate 14 and the cavity 4 is set large, and thereby the molten resin P1 can smoothly flow from the inside of the recessed gate 14 into the cavity 4, and the moldability of the disk substrate 23 can be enhanced.

(8) Description of a fifth embodiment of a molding apparatus for injection molding a disk substrate

A fifth embodiment of the molding apparatus 1 is described below with reference to fig. 20 and 21. In this case, at a corner portion on the outer circumferential side of the top face of the tip end portion 7a of the recessed gate forming recessed portion 12 of the recessed gate cutter 7 in the fourth embodiment shown in fig. 18 and 19, a second R surface molding portion (or a second C surface molding portion) 20 is provided.

As shown in fig. 20, a molten resin P1 is injected into the cavity 4 through the recessed gate 14, thereby molding the disk substrate 23. At the moment when the molten resin P1 solidifies to some extent (at the moment when the disk substrate 23 can be compressed), the recessed gate cutter 7 advances in the arrow b direction, cutting the gate, as shown in fig. 21. At the time of gate cutting, an edge portion on the opposite side of the center hole 24 of the disk substrate 23 from the signal transfer surface 13 side molds a second R surface (or a second C surface) 24d with a second R surface molding portion (or a second C surface molding portion) 20.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible based on the technical idea of the present invention.

The disk substrate, the molding apparatus for injection molding the substrate, and the disk substrate take-out robot according to the present invention configured as described above have the following effects.

The disk substrate according to the present invention has a structure in which: at least the edge on the signal transmission surface side of the center hole is completely free of flash, or even if flash is generated at this point, the height of this flash may be limited to 10 μm or less. Therefore, the disk substrate can be centered with high accuracy by the center pin of the spindle motor, and the eccentric amount of the disk substrate can be limited when the disk substrate is driven to rotate. Accordingly, stable recording and reproduction is achieved in a high-density recording disc. In addition, since the central hole is free of flash, less waste is generated in production and a disc containing little air can be transported, which results in higher yield.

In addition to this, since the first R surface or the first C surface is formed at least at the edge on the signal transmission surface side of the center hole, the edge is completely free of flash.

Since the straight portion whose aperture is parallel to the axial direction is provided on the side of the center hole opposite to the signal transfer surface side and the tapered portion whose aperture is gradually enlarged toward the signal transfer surface is provided between the straight portion of the center hole and the signal transfer surface, a flash is less likely to be generated at the edge on the signal transfer surface side of the center hole, and even if a flash is generated at this edge, the adverse effect of this flash on the centering of the disk substrate can be minimized.

An injection molding apparatus according to the present invention includes: a pressing die disposed on one side of the fixed platen of the cavity; a recessed gate forming protrusion provided on an outer circumference of a tip end of the injection port; a recessed gate forming recessed portion provided on a tip end of a recessed gate cutter disposed on one side of the movable platen; and a center hole molding portion provided on the recessed gate forming projecting portion, and the injection molding apparatus of the present invention employs a recessed gate cutting structure with respect to a signal transmitting surface of the disk substrate injection-molded in the cavity. Therefore, when the disk substrate is injection molded, the center hole is simultaneously injection molded with the center hole molding portion. Thus, when a recessed gate cutter whose tip is recessed in shape is advanced from the movable platen side to perform gate cutting, a center hole free from flash at both end edges thereof can be produced. Accordingly, by using the fixed-side stamper in the same manner as in the related art, a disk substrate whose central hole does not contain flash can be injection-molded while preventing the deformation of the pits and grooves. Since the central hole molding portion is disposed on the side of the fixed die, the amount of eccentricity of the groove with respect to the central hole can be restricted to a minimum, and the tracking servo signal or the like can be read with high accuracy.

The center hole molding portion is provided with a first R surface molding portion or a first C surface molding portion for molding a first R surface or a first C surface on an edge on the signal transmitting surface side of the center hole. Therefore, when the disk substrate is injection-molded, the first R surface or the first C surface is simultaneously injection-molded on the edge of the signal transmission surface side of the center hole, thereby preventing generation of flash on the edge.

The central hole molding projection is provided with a straight-line molding portion for molding a straight-line portion on a side of the central hole opposite to the signal transmitting surface; and, the central hole molding portion is provided with a tapered molding portion for molding a tapered portion whose hole diameter is gradually enlarged from the central hole straight portion toward the signal transmission surface side. Therefore, when the disk substrate is injection-molded, the straight portion and the tapered portion can be simultaneously injection-molded with respect to the central hole, and when the movable platen is opened, the disk substrate is easily released from the press mold.

In addition, the advancing amount of the gate cutter is set equal to or larger than the gate thickness, and desirably set equal to or smaller than the gate thickness +0.5mm, whereby the recessed gate cutting can be performed safely.

In addition to this, the position at which the recessed gate is cut by the recessed gate cutter is set at the position of the aperture of the straight portion of the center hole, and thus, no flash or the like is generated in the straight portion.

A second R surface molding portion or a second C surface molding portion for molding a second R surface or a second C surface on an edge on the side of the center hole opposite to the signal transmission surface side is provided on an outer circumferential portion tip of a recessed gate forming recessed portion of the recessed gate cutting machine. Therefore, the second R surface or the second C surface may be molded on the edge of the side of the center hole opposite to the signal transfer surface side.

In addition to this, the position at which the recessed gate is cut with the recessed gate cutter is set at two inner and outer positions, i.e., a first cutting position set at the aperture position of the straight portion of the central hole and a second cutting position located inside the first cutting position, wherein the diameter of the second cutting position is smaller than the diameter of the first cutting position. Therefore, after the gate cutting of the molded disc substrate, the maximum outer diameters of the sprue and gate residual resin can be made sufficiently smaller than the inner diameter of the linear portion of the center hole; accordingly, when the robot arm grips the disk substrate and transfers the disk substrate to the aligner, the gate and sprue residual resins are easily discharged to either side or the other side of the disk substrate through the central hole of the disk substrate.

The disk substrate take-out apparatus according to the present invention is configured such that: the gate cutting is performed from the movable platen side with a recessed gate cutter, and a robot for taking out the disk substrate from the movable platen is provided with a means for discharging the sprue and gate residual resin to the movable platen side with respect to the disk substrate released from the fixed platen together with the movable platen by opening the movable platen after the injection molding. Therefore, even if the injection port and the gate residual resin are pushed onto the side of the surface of the disk substrate opposite to the signal transmission surface, which is the opposite direction to that in the prior art, the injection port and the gate residual resin are easily discharged from the inside of the center hole. Accordingly, a disk substrate take-out apparatus optimally applied to a molding apparatus having a recessed gate cutting structure can be provided.

In addition, the apparatus for discharging the sprue and gate residual resin is provided with an air nozzle, and a discharging operation of discharging the sprue and gate residual resin to the movable platen side after removing the sprue and gate residual resin from the mold can be performed safely and instantaneously.

Claims (9)

1. A disk substrate, wherein a signal is transferred to the substrate by injection molding, the disk substrate comprising a central hole; and an edge having a flash at least on a signal transmission surface side of the center hole, wherein a flash height is reduced to zero or limited to 10 μm or less,

wherein at least the edge of the center hole is provided with an R surface or a C surface on a signal transfer surface side,

and the disk substrate further includes: a linear portion having an aperture in the same direction as the axial direction, the linear portion being provided on a side of the center hole opposite to the signal transmission surface side; and a tapered portion whose aperture gradually enlarges toward the signal transfer surface, the tapered portion being provided between the linear portion of the center hole and the signal transfer surface.

2. A molding apparatus for injection molding a disk substrate, which includes a cavity into which a molten resin is injected through an injection port and a recessed gate, and a signal transfer stamper disposed on a stationary platen side of the cavity, the molding apparatus comprising: a convex portion for molding the recessed gate disposed at a tip end of the sprue; a concave portion for molding the recessed gate, the concave portion being arranged on a tip end of a recessed gate cutter arranged on a movable platen side opposite to the convex portion; and a center hole molding part provided on an outer circumference of the sprue,

wherein the central hole molding part comprises: a first R-surface molding part or a first C-surface molding part for molding a first R surface or a first C surface at an edge on the signal transmission surface side of the center hole of the injection-molded disc substrate within the cavity, and

wherein the central hole molding part comprises: a straight-line molding portion for molding a straight-line portion having an aperture direction equal to an axial direction on a side of the center hole of the injection-molded disc substrate opposite to a signal transmission surface side within the cavity; and a tapered molding portion for molding a tapered portion whose aperture gradually expands toward the signal transfer surface side between the straight portion of the center hole of the injection-molded disc substrate and the signal transfer surface in the cavity.

3. A molding apparatus for injection molding a disk substrate according to claim 2, wherein the forward amount of the recessed gate cutter is not less than the thickness of the recessed gate and not more than the thickness of the recessed gate plus 0.5 mm.

4. A molding apparatus for injection molding a disk substrate according to claim 2, wherein a position at which said recessed gate is cut by said recessed gate cutter is set at a position equal to an aperture diameter of said straight portion of said center hole.

5. A molding apparatus for injection-molding a disk substrate according to claim 4, wherein the recessed gate cutter includes a second R-surface molding portion or a second C-surface molding portion on a tip of an outer circumferential portion of the recessed portion for molding a second R-surface or a second C-surface at an edge on a side of the center hole opposite to the signal transmission surface side.

6. A molding apparatus for injection molding a disk substrate according to claim 2, wherein a position at which said recessed gate is cut by a recessed gate cutter is set at a first position equal to a hole diameter of said straight portion of said central hole and at a second position located within said first position and having a diameter smaller than said first position.

7. A molding apparatus for injection-molding a disk substrate according to claim 6, wherein the recessed gate cutter includes a second R-surface molding portion or a second C-surface molding portion on a tip of an outer circumferential portion of the recessed portion for molding a second R-surface or a second C-surface at an edge on a side of the center hole opposite to the signal transmission surface side.

8. A disk substrate take-out apparatus comprising:

a molding apparatus comprising a cavity provided between a fixed platen and a movable platen, a signal transmission stamper disposed on a side of the fixed platen of the cavity, and a recessed gate cutter disposed on a side of the movable platen, wherein a molten resin is injected into the cavity through an injection port and a recessed gate to mold a disk substrate; and, gate cutting is performed from the movable platen side with the recessed gate cutter; and

a robot for taking out the disk substrate from the movable platen, wherein the disk substrate is released from the fixed platen together with the movable platen by opening the movable platen after injection molding, the robot comprising: means for discharging the inlet and gate residual resin to the side of said movable platen opposite to said disk substrate,

wherein the central hole molding part comprises: a first R-surface molding part or a first C-surface molding part for molding a first R surface or a first C surface at an edge on the signal transmission surface side of the center hole of the injection-molded disc substrate within the cavity, and

wherein the central hole molding part comprises: a straight-line molding portion for molding a straight-line portion having an aperture direction equal to an axial direction on a side of the center hole of the injection-molded disc substrate opposite to a signal transmission surface side within the cavity; and a tapered molding portion for molding a tapered portion whose aperture gradually expands toward the signal transfer surface side between the straight portion of the center hole of the injection-molded disc substrate and the signal transfer surface in the cavity.

9. The disk substrate take-out apparatus as claimed in claim 8, wherein the unloading device is provided with an air nozzle.