JP3228026B2 - Apparatus and method for manufacturing optical disc substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for manufacturing an optical disk substrate for forming a substrate used for an optical disk or the like.

[0002]

2. Description of the Related Art In recent years, optical disks have been receiving attention as large-capacity, high-speed memory media. As optical disks, read-only optical disks (CD, VD, CD-ROM, etc.), recording / reproducing optical disks (write-once type), recording / reproducing erasable optical disks (rewritable type) and the like are known.

[0003] Resin substrates (polycarbonate resin, acrylic resin, polyolefin resin, etc.) are generally used as these optical disk substrates.

[0004] Optical disc substrates are required to have characteristics such as birefringence, warpage, plate thickness, signal pit formation accuracy, appearance, dimensions, and low cost.

[0005] For this reason, an optical disk substrate is generally formed by injection molding or injection compression molding.

That is, an annular flat stamper is mounted in a cavity formed between the fixed mold and the movable mold in a clamped state, and a molten resin material is injected into the cavity to form the stamper. Then, a flat optical disc substrate on which the pits and grooves are transferred is formed.

There are a toggle system and a direct pressure system in the injection molding machine. In this embodiment, the description will be made based on the toggle system.

FIG. 6 is a structural view showing the structure of the mold opening / closing section and the mold section of the injection molding machine. Mold part G in FIG. 6
Is composed of a fixed mold 101a and a movable mold 101b.
Reference numerals 03a and 103b denote mold cooling water passages that pass through the fixed mold and the movable mold.

Reference numeral 104 denotes a stamper, 105 denotes a stamper holder, and 106 and 107 denote large plates of a molding machine.

A stamper 104 is attached to the movable mold 101b by a stamper holder 105. Fixed mold 1
01a and the movable mold 101b are bolted or the like.
It is attached to large plates 106 and 107.

108 is a tie bar, 109 is a toggle, 110
Is a mold opening / closing hydraulic circuit, and 111 is a hydraulic cylinder. 1
12 and 113 are hydraulic circuits. The hydraulic cylinder 111 is driven by the mold opening / closing hydraulic circuit 110 so that the toggle 10
By moving 9, the large plate 107 to which the movable mold 101b is attached moves the tie bar 108 in parallel with the guide, and the movable mold 101b is fitted to the fixed mold 101a and separated.

The hydraulic circuit 112 adjusts the clamping pressure of the fixed mold 101a and the movable mold 101b, and the hydraulic circuit 113 applies the injection compression pressure to the movable mold 101b.

FIG. 7 is a structural view showing the structure of the emitting section.
In FIG. 7, 131 is a resin material, 133 is a screw,
134 is a motor, 135 is a heating cylinder, 136 is a heater, 137 is an injection hydraulic cylinder, 138 is an injection hydraulic circuit, and 139 is a nozzle.

After the resin material 131 is sufficiently dried, the resin material 131 is guided to the screw 133, and is sent to the heating cylinder 135 by the rotation of the screw 133. Heating cylinder 135
Is heated to a predetermined temperature by the heater 136, and the resin material 131 is melt-kneaded. The injection hydraulic circuit 138 operates the injection hydraulic cylinder 137 to advance the screw 133 attached to the tip of the injection hydraulic cylinder, and the molten resin material is injected from the nozzle 139 to the mold part G.

A conventional injection molding method will be described with reference to the molding process sectional views shown in FIGS. First, the molten resin material is injected into a pair of dies that have been filled. The injected molten resin material is cooled and solidified in the mold. During the cooling and solidifying time, the resin to be injected next is melted and measured.

After the cooling and solidification of the resin material is completed, a pair of dies is separated and a finished product is taken out to complete a molded substrate.

Here, the mold clamping is for filling the fixed mold 101a and the movable mold 101b as shown in FIG. 9 (a).
b moves and is packed.

In the injection, as shown in FIG. 9B, the resin material 131 moves to the heating cylinder 135 by the rotation of the screw 133, and is melted by the heating cylinder 135 heated to a predetermined temperature.

Then, the screw 133 is injected into the mold from the nozzle 139 by the advance of the screw 133. At this time, if the molten resin material is injected at a high speed from the beginning or stopped at a high speed, an irregular flow occurs in the mold, and the required characteristics of the optical disk substrate cannot be obtained.

Therefore, when injecting the molten resin material, "program injection control" for switching the speed in multiple stages is used.

At the time of this injection, an injection compression molding method is used to secure the thickness of the optical disk substrate.
In the injection compression molding method, as shown in FIGS. 9 (c) to 9 (e), when the molten resin material is injected into the mold portion G , the mold is opened from the thickness of the substrate product, and the molten resin material is melted. After sufficiently filling the resin material into the mold, the injection compression pressure is increased. This ensures the thickness of the plate and the accuracy of forming the signal pits.

As shown in FIG. 10A, the molten resin material is cooled and solidified in a mold. Next, in the material melting and metering, as shown in FIG. 10B, the resin material is moved to the heating cylinder 135 by the rotation of the screw 133,
The resin is melted by the heat of the heater 136 and the heat generated by the resin itself due to the rotation of the screw 133, and accumulates at the tip of the heating cylinder 135.

The screw 133 includes a heating cylinder 135.
The retraction is started by the pushing force of the molten resin material accumulated at the tip of the. By limiting the retreat distance, the amount of the molten resin material stored in the heating cylinder 135 and the tip of the screw 133 becomes an amount corresponding to the next injection capacity. The setting of the retreat distance is adjusted by an operator while measuring the molded product.

Also, in order to reduce the variation in the injection capacity, a method is adopted in which the screw rotation speed is reduced just before the screw 133 retreat operation is completed, the inertia is reduced, the retreat is completed, and the retreat operation end position accuracy is increased. (Japanese Patent Publication No. 52-43869).

As shown in FIG. 10C, the fixed mold 101a and the movable mold 101b are separated by the mold opening. At this time, the molded product is attached to the movable mold 101b.

Next, as shown in FIG. 10 (d), the finished product, which has been cooled and solidified, is taken out of the mold by a substrate take-out device.

Normally, the steps shown in FIG. 9 and FIG. 10 are performed continuously, and in that sense, FIG. 9 and FIG. Due to the size of the paper, the drawing is divided into two figures.

As described above, the adjustment of the thickness and weight of the optical disk substrate when forming the optical disk substrate can be performed by: (a) stabilizing the resin measurement (stabilizing the retraction stop position of the screw 133);
(b) Due to the increase of the mold clamping force, etc., the thickness accuracy width of the optical disk substrate is ± 10% and the weight accuracy width is ± 3% due to variations in the surface condition of each stamper and fluctuations in molding conditions.
It is about.

For this reason, in order to increase the precision and quality of the sheet thickness, frequent sheet thickness measurement and adjustment operations are required in the manufacturing process, and the sheet thickness adjustment requires a long time, resulting in poor yield. This has led to increased manufacturing costs.

[0030]

At present, there is a demand for a substrate for an optical disk having a higher density. In order to increase the density, it is necessary to increase the aperture of the objective lens in order to improve the aperture of the irradiation light on the optical disk. In this case, the aberration due to the inclination is proportional to the plate thickness and proportional to the cube of the aperture.

Therefore, since the plate thickness is reduced and the stabilization of the plate thickness greatly affects the control of the pickup, the plate thickness is required to be highly accurate and stable. For this reason, in the manufacturing process, frequent thickness measurement and adjustment work are required to stabilize the thickness for a high-density optical disk, and a long time is required for the thickness adjustment, resulting in poor yield and low manufacturing cost. Has led to a rise. The adjustment of the sheet thickness is manually performed, and it is extremely difficult to stabilize the sheet thickness due to a difference in the stamper surface condition at the time of stamper replacement and a change in molding conditions.

In view of the above problems, the present invention has a thickness of 1.5 m.
It is intended to stably provide an optical disc substrate having a highly accurate plate thickness in molding a thin resin substrate having a thickness of not more than m.

[0033]

An apparatus and a method for manufacturing an optical disk substrate according to the present invention for solving the above-mentioned problems are provided by injection molding or injection compression molding of the optical disk substrate.
Sometimes, the thickness of the cavity at the time of molding is measured, and the screw injection speed of the molding machine or the screw injection speed switching position is automatically switched based on the measured value.

[0034]

[0035]

According to the present invention, the above structure eliminates the need for frequent thickness measurement and adjustment work in the process of manufacturing a high-precision optical disk substrate, thereby reducing measurement and adjustment time and improving and stabilizing the thickness accuracy. Is achieved.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method for manufacturing an optical disk substrate according to the present invention will be described with reference to the drawings .

[0037](Reference example)  Figure 1Reference exampleManufacturing equipment. In FIG. 1, 1a is fixed.
Reference numeral 1b denotes a movable die. Fixed mold 1a and
The movable mold 1b includes large plates 6 and 7 as shown in FIG.
Is fixed with bolts, etc.
The movable mold 1b is fitted and separated from the fixed mold 1a.

When the movable mold 1b and the fixed mold 1a are fitted, a cavity 2 is formed between the two molds. Here, 8 is a diver, 9 is a toggle, 10 is a mold opening / closing hydraulic circuit, 11 is a hydraulic cylinder, and 12 and 13 are hydraulic circuits.

33 is a screw, 34 is a motor, 35 is a heating cylinder, 36 is a heating control device, 37 is an injection hydraulic cylinder, 38 is an injection hydraulic circuit, and 39 is a nozzle.
51 is a substrate unloading device, 52 is a substrate measuring device, and 54 is an injection control device.

The mold part A comprises a fixed mold 1a, a movable mold 1b and a cavity 2. The mold opening / closing section B includes large plates 6 and 7, a diver 8, a toggle 9, a mold opening / closing hydraulic circuit 10, a hydraulic cylinder 11, and hydraulic circuits 12 and 13.

The C heating unit includes a heating cylinder 35 and a heating control device 36. D injection part is screw 33,
Motor 34, injection hydraulic cylinder 37, injection hydraulic circuit 3
8, the nozzle 39. The E measuring unit includes a substrate unloading device 51 and a substrate measuring device 52.

FIG. 2 is a block diagram showing the control for measuring the plate thickness. 61 is an optical disk substrate, 62 is a laser generator, 63 is a substrate thickness measurement sensor, 64 is a substrate thickness setting device, and 65 is a substrate thickness calculator. 54 is an injection control device, 38 is an injection hydraulic circuit, 37 is an injection hydraulic cylinder,
33 is a screw, 35 is a heating cylinder.

First, the dried resin material is sent to the screw 33 and melted and kneaded by the rotation of the screw 33 and the heat of the heating cylinder 35.

Next, while the fixed mold 1a and the movable mold 1b are clamped by the mold opening / closing hydraulic circuit 10, the hydraulic cylinder 11, and the toggle 9, the molten resin material is supplied to the injection hydraulic circuit 38 and the injection hydraulic circuit. When the screw 33 is advanced by the cylinder 37, the screw 33 is injected into the cavity 2 through the nozzle 39. Then, after filling the molten resin material, the screw 33 is held under pressure by the injection hydraulic circuit 38 in order to prevent the reflux of the resin material. In a state where the movable mold 1b is clamped to the fixed mold 1a via the tie bar 8 by the hydraulic circuit 12, the central part of the movable mold 1b is cooled by applying an injection compression pressure to the center of the movable mold 1b by the hydraulic circuit 13. 1b is separated from the fixed mold 1a, and the molded substrate is taken out by the substrate take-out device 51.

Next, the substrate is set in the substrate measuring device 52 by the substrate unloading device 51 and the thickness or weight is measured. The injection controller D controls the injection unit D based on the measurement data. At this time, as shown in FIG. 2, the plate thickness measurement configuration and the control circuit irradiate a laser beam from a laser generator 62 to an optical disk substrate 61 taken out of the die, and a substrate thickness measurement sensor 6
Measure the plate thickness according to 3.

The measured value is compared with the value set by the substrate thickness setting unit 64 in the substrate thickness calculator 65 and is compared by the injection control device 54, the injection hydraulic circuit 38, and the injection hydraulic cylinder 37 with reference to FIG. As shown, the injection speed deceleration position A or the injection speed of the screw 33 is automatically adjusted to make the plate thickness or weight constant. It should be noted that participation
Although the present invention has been described with reference to the toggle-type molding machine, the present invention may be applied to a direct-pressure molding machine.

(Embodiment 1 ) FIG. 3 is a schematic diagram showing a configuration of a manufacturing apparatus according to a first embodiment of the present invention. 1a is a fixed mold, and 1b is a movable mold. The fixed mold 1a and the movable mold 1b are fixed to the large plates 6, 7 with bolts and the like as shown in FIG.

The movable mold 1b is fitted and separated from the fixed mold 1a by the mold opening / closing section B shown in FIG.

When the movable mold 1b and the fixed mold 1a are fitted together, a cavity 2 is formed between the two molds. 8 is a diver, 9
Is a toggle, 10 is a mold opening / closing hydraulic circuit, 11 is a hydraulic cylinder, and 12 and 13 are hydraulic circuits. 33 is a screw,
34 is a motor, 35 is a heating cylinder, 37 is an injection hydraulic cylinder, 38 is an injection hydraulic circuit, and 39 is a nozzle.
51 is a substrate unloading device, 54 is an injection control device, 72 is a cavity thickness measuring device, and 73 is a cavity thickness calculating device.

The mold part A includes a fixed mold 1a and a movable mold 1b.
And the cavity 2. The mold opening / closing section B includes large plates 6 and 7, a diver 8, a toggle 9, a mold opening / closing hydraulic circuit 10, a hydraulic cylinder 11, and hydraulic circuits 12 and 13. The heating section C includes a heating cylinder 35 and a heating control device 36. Injection part D is screw 3
3, a motor 34, an injection hydraulic cylinder 37, an injection hydraulic circuit 38, and a nozzle 39. The measuring unit E includes a substrate unloading device 51, a cavity thickness measuring device 72, and a cavity thickness calculating device 73.

FIG. 4 is a control block diagram for measuring the cavity thickness. 72 is a cavity thickness measuring device, 74 is a cavity thickness setting device, and 75 is a cavity thickness calculator. 54
Is an injection control device, 38 is an injection hydraulic circuit, 37 is an injection hydraulic cylinder, 33 is a screw, and 35 is a heating cylinder.

The first embodiment will be described below with reference to the drawings. First, the dried resin material is sent to the screw 33,
Melting and kneading are performed by the rotation of the screw 33 and the heat of the heating cylinder 35.

With the fixed mold 1a and the movable mold 1b clamped by the mold opening / closing hydraulic circuit 10, the hydraulic cylinder 11, and the toggle 9, the molten resin material is injected into the injection hydraulic circuit 38,
The screw 33 is advanced into the cavity 2 through the nozzle 39 by the advancement of the screw 33 by the injection hydraulic cylinder 37, and then the screw 33 is held under pressure by the injection hydraulic circuit 38 in order to prevent the resin material from returning after the filling of the molten resin material. And then the fixed mold 1 via the tie bar 8 by the hydraulic circuit 12.
In a state where the movable mold 1b is clamped to a, a hydraulic circuit 13 applies an injection compression pressure to the center of the movable mold 1b to cool it.

When the resin is cooled, the cavity thickness between the fixed mold 1a and the movable mold 1b is measured by the cavity thickness measuring device 72 attached to the fixed mold 1a and the movable mold 1b. The movable mold 1b is separated from the fixed mold 1a, and the molded substrate is taken out by the substrate take-out device 51.

Here, the injection controller D controls the injection section D based on the data of the cavity thickness measured by the cavity thickness measuring device 72.

At this time, as shown in FIG. 4, the cavity thickness measuring structure and the control circuit, when the injection is completed and the cooling is performed, the cavity thickness measuring device 72 attached to the fixed mold 1a and the movable mold 1b. , And compares this value with the value set by the cavity thickness setting unit 74 in the cavity thickness calculator 75. The injection control device 54, the injection hydraulic circuit 38, and the injection hydraulic cylinder 37 use FIG.
By automatically adjusting the injection speed deceleration position A of the screw 33 or the injection speed of the screw 33, as shown in FIG.

Although the present embodiment has been described using the toggle molding machine, the present invention can be applied to a direct pressure molding machine.

[0058]

According to the present invention, the screw speed or screw speed of the injection unit in the next molding cycle is determined based on the measured data of the cavity thickness when the molten resin is filled and solidified in the cavity formed between the pair of closed molds. By automatically adjusting the switching position of the speed, it is possible to make the variation within the thickness accuracy width ± 3% and the weight accuracy width ± 1%, and to reduce the measurement work , the thickness adjustment work, and the yield. Improvements could be made. This has made it possible to supply high-density, high-quality optical discs at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a manufacturing apparatus of a reference example .

FIG. 2 is a control block diagram of the reference example apparatus .

FIG. 3 is a configuration diagram of a manufacturing apparatus according to the first embodiment of the present invention.

FIG. 4 is a control block diagram in the apparatus of the embodiment.

FIG. 5 is a view showing a relationship between a screw position and a screw speed in the embodiment.

FIG. 6 is a structural diagram of an injection molding machine used for manufacturing a conventional optical disc substrate.

FIG. 7 is a structural view of an injection unit of the injection molding machine.

FIG. 8 is an injection molding process diagram.

FIG. 9 is a cross-sectional view of a molding process in the production of a conventional optical disc substrate.

FIG. 10 is a sectional view showing a conventional optical disk substrate injection molding process.

[Explanation of symbols]

1a Fixed mold 1b Movable mold 2 Cavity 6,7 Large plate 8 Diver 9 Toggle 10 Mold opening and closing hydraulic circuit 11 Hydraulic cylinder 12 Hydraulic circuit 13 Hydraulic circuit 33 Screw 34 Motor 35 Heating cylinder 36 Heating control device 37 Injection hydraulic cylinder 38 Injection hydraulic circuit 39 Nozzle 51 Substrate unloading device 52 Substrate measuring device 54 Injection control device 61 Optical disk substrate 62 Laser generator 63 Substrate thickness measuring sensor 64 Substrate thickness setting device 65 Substrate thickness calculator 72 Cavity thickness measuring device 73 Cavity thickness calculation Apparatus 74 Cavity thickness setting device 75 Cavity thickness calculator A Mold part B Mold opening / closing part C Heating part D Injection part E Measurement part

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-104726 (JP, A) JP-A-5-42567 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/00-45/84 G11B 7/26 521

Claims (2)

(57) [Claims] An apparatus for manufacturing an optical disk substrate by injecting a molten resin into a cavity formed between a pair of molds, comprising: a mold opening / closing section for opening and closing the pair of molds. And a heating unit for melting the resin, an injection unit for filling the cavity between the pair of closed molds with the molten resin, and an injection for controlling the injection speed of the injection unit or the injection speed switching position. An apparatus for manufacturing an optical disk substrate, comprising: a control unit; and a measuring unit for measuring a cavity thickness after injection molding, wherein the injection control unit is controlled according to a value of the measuring unit. 2. An optical disk for manufacturing an optical disk substrate by injecting a molten resin with a screw into a cavity formed between a pair of molds and press-molding the injected molten resin with the mold. A method of manufacturing a substrate for measuring the thickness of a cavity after injection molding a molten resin into a cavity formed between a pair of molds, based on the value, the speed of the screw to inject the molten resin or A method for manufacturing an optical disc substrate, comprising controlling at least one of a switching position of a screw speed.