JPH05223781A - Method and device for evaluating optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical information recording medium evaluating method by eliminating faults caused by the electrification of an injection-molded substrate. CONSTITUTION:An injection-molded substrate 3 is positioned above a metallic turntable 4. A surface potential measuring probe 1 is provided on the upper surface of the substrate 3 for measuring the surface potential of the substrate 3. The prove 1 is moved in both the horizontal and vertical directions against the substrate 3. In addition, the surface potential of the substrate 3 detected by means of the probe 1 is measured by means of a surface-electrometer 2 and recorded on recording paper by means of a recorder 6. By measuring the surface potential of the injection-molded substrate and checking the distributions of maximum surface potential values and surface potentials in such way, the quality of the substrate is discriminated.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical information recording medium evaluation method and evaluation apparatus. For example, it is applied to an optical disk or an optical card.

[0002]

2. Description of the Related Art In the conventional evaluation of an injection-molded substrate and determination of injection-molding conditions, the mechanical properties or optical properties of a substrate usually produced by injection molding, particularly birefringence, etc., are measured and evaluated. The injection molding conditions were set. In addition, the defect inspection of the injection-molded substrate has been performed by irradiating the substrate with a light source and capturing a change in the amount of transmitted light, reflected light, diffracted light, scattered light, or the like. However, in the conventional injection-molded board evaluation method, injection-molded condition determination method, and injection-molded board defect inspection method, it is possible to know the surface condition (charged state of the surface) of the injection-molded board and distortion inside the injection-molded board. Can not.

For example, so-called "peeling charging" occurs at the time of release from injection molding. However, due to a defective injection molding machine, peeling charging is more likely to occur than in a normal state. Despite good characteristics and birefringence value, dust and dust are more likely to adhere to the surface-charged part during actual use, causing read errors and tracking errors, and further malfunctioning of the electric circuit due to substrate charging. The semiconductor laser may also be damaged.

As described above, the cause of electrification that causes problems such as the occurrence of reading errors and tracking errors, the occurrence of malfunction of electric circuits, and the damage of semiconductor lasers is not limited to the peeling electrification at the time of exfoliation, but at the time of injection molding It is also caused by the mechano-electret phenomenon (due to the orientation of molecules) in which permanent electrification appears due to mechanical deformation of the polymer, and in the case of extruding a polymer compound in a molten state from a thin nozzle, contact with the inner wall of the nozzle. As a method for improving various problems caused by charging due to these phenomena, for example,
Means such as providing a protective layer containing an antistatic agent are taken. However, if the substrate is considerably charged, the protective layer will certainly have the effect of reducing the adhesion of dust and dust on the reading surface, but it will adversely affect the film formation of the recording film and the protective layer, resulting in uniform defects. It becomes difficult to form a recording film or a protective layer without a mark.

Further, for example, in the case of an optical information recording medium of air sandwich structure, when dyes are used for the recording layer, the charging of the substrate, especially the non-uniform charging (in the plane of the substrate) is adversely affected by the scattered pigment. The air sandwich structure type optical information recording medium is usually provided with a ventilation hole as a measure against atmospheric pressure, so there is a risk that dust and dirt may enter from there, and The adhesion is locally concentrated due to the electrification of the substrate and causes various errors.

[0006]

[Purpose] The present invention has been made in view of the above-mentioned circumstances, and a reading error and a tracking error due to the charging of an injection-molded substrate, a malfunction of an electric circuit,
The present invention has been made for the purpose of providing an evaluation method and an evaluation apparatus for an optical information recording medium for solving a problem such as breakage of a semiconductor laser.

[0007]

In order to achieve the above object, the present invention provides (1)
In a method for evaluating a substrate for an optical information recording medium by an injection molding method, the substrate is evaluated by measuring the surface potential of the substrate, or (2) reflected light, transmitted light, diffracted light by light source irradiation And the like, to evaluate the substrate by a method of detecting a defect in the substrate by reading changes in the substrate and a method of detecting a charging state of the substrate by measuring a surface potential, or (3) a turntable, An injection molded substrate arranged on the turntable, a movable surface potential measuring probe provided above the injection molded substrate, and a surface potential for measuring the surface potential of the substrate by the surface potential measuring probe. It is characterized in that the substrate is evaluated by measuring the surface potential of the substrate. That is, the focus is on the charging of the injection-molded substrate, which causes problems such as the occurrence of reading errors and tracking errors, the occurrence of malfunctions of electric circuits, and the damage of semiconductor lasers. An evaluation method, a defect inspection method for an injection-molded substrate, and an apparatus therefor are provided. Hereinafter, description will be given based on examples of the present invention.

FIG. 1 is a block diagram for explaining an embodiment of a surface potential measuring apparatus for evaluating an optical information recording medium according to the present invention, in which 1 is a surface potential measuring probe,
Reference numeral 2 is a surface electrometer, 3 is an injection molded substrate, 4 is a metal turntable, 5 is an electrostatic shield, and 6 is a recorder. Specifically, the surface potential of the injection-molded substrate 3 is measured, and the maximum value of the surface potential and the distribution of the surface potential are examined to determine whether the substrate is good or defective. The injection-molded substrate 3 is placed on the metal turntable 4. A surface potential measuring probe 1 for measuring the surface potential of the injection molded substrate 3 is provided on the upper surface of the injection molded substrate 3.

The surface potential measuring probe 1 is moved in the horizontal and vertical directions (arrow directions in the drawing) with respect to the injection-molded substrate 3. The surface potential of the injection-molded substrate 3 detected by the surface potential measuring probe 1 is measured by the surface electrometer 2 and recorded on recording paper by the recorder 6. The metal turntable 4 and the surface potential measuring probe are shielded by an electrostatic shield 5.

FIGS. 2A to 2C are views showing the surface potential distribution of the substrate. The substrate of FIG. 2A shows a place where the surface potential is locally high within one round of the disk and one round of the disk. It can be judged as good because the unevenness of the surface potential within the minute is not so large, but in the cases of Fig. (B) and Fig. (C), there is an abnormally high surface potential in the disk, or there is one disk circumference. It is judged to be defective because there is a place where the fluctuation of the surface potential is locally large. Judgment of these goodness and badness (unevenness in the disc and the threshold value of the surface potential) was made by an experiment.
It is preferable to determine the standard. By measuring this surface potential, it is possible to easily evaluate the substrate, and evaluate whether the hard coat layer or the protective layer has good charging characteristics and molding conditions. Further, it is also applied as a defect detection of an injection molded substrate.

Specific embodiments will be described below. A polycarbonate substrate of 130 mmφ and 1.2 mmt was injection molded using three types of stampers, each of which was 1,000
Continuous molding was performed one by one. Any of these injection molded substrates
0 sheets were extracted and the surface potential of the injection-molded substrate was measured at the position of r = 50 mm over the entire circumference by the surface potential measuring device shown in FIG. 3 to 5 are diagrams showing the results of the surface potential distribution of the three types of injection molded substrates. As can be seen from this result, there is not much difference in the surface potential distribution between the same lots (same mold, same stamper), but when the molds and stampers change (different lots), the surface potential distribution becomes large. Change. This is because the molding state and the peeling state slightly change when the stamper or the mold is removed or attached (variation of molding conditions).

Ten of the above three types of injection-molded substrates were set in the drive (laser-off state) at 1800 rpm for 5 minutes.
It was operated continuously for 0 hr. At this time, the drive was installed in the dust test chamber so that dust and dirt could easily adhere to the rotating injection-molded substrate. After continuous operation for 50 hours, the injection-molded substrate was set in a drive installed in a normal room, and when 0 sectors to 15000 sectors were read one sector at a time, focus error and tracking error occurred on a certain substrate. In some cases, the read status did not occur. The results are shown in Table 1 below, but read errors are apt to occur particularly on the substrate formed by injection with the stamper 1 shown in FIG. 3, followed by the stamper 3 shown in FIG. 5 and the stamper 2 shown in FIG. ..

[0013]

[Table 1]

This result agrees with the result of measuring the surface potential previously, and the substrate having a higher surface potential has a more dirty surface and is more likely to have dust or dust. Therefore, it can be understood from this result that measuring the surface potential is an evaluation method for the injection-molded substrate and the injection-molding conditions. That is,
By setting the absolute maximum value of the surface potential to 300 V from the results of the examples of the present invention (results of the surface potential and the read defect occurrence rate between 0 to 15000 sectors), it is possible to evaluate the substrate and the molding method. A substrate having a surface potential of more than 300 V can be judged to be defective, and a substrate having a surface potential of 300 V or less can be judged to be good.

However, the method of selecting the threshold value of the surface potential is arbitrary. In addition, since the surface potential also changes significantly by changing the molding conditions, the molding conditions are evaluated in combination with the conventional method so that the surface potential is 300 V or less, or the molding conditions satisfying the conventional inspection items. You just have to choose the conditions. By evaluating the substrate in this way, only highly reliable substrates can be easily selected. Further, at the same time, the defect inspection of the injection-molded substrate is expected to be further enhanced by using it together with the conventional defect inspection, and it is possible to eliminate the bad influence due to the electrification of the injection-molded substrate, which cannot be prevented by the conventional method.

[0016]

[Effect] As is apparent from the above description, according to the present invention, by using the injection molding substrate evaluation method, the defect inspection method, and the injection molding evaluation method, it is possible to perform inspection by measuring conventional mechanical characteristics, birefringence, and the like. Can obtain information on the surface or inside of the injection-molded substrate that could not be detected by the evaluation method or the evaluation method. In particular, reading errors and tracking errors due to electrification of the injection-molded substrate, malfunctions of electrical circuits, semiconductor lasers, etc. It is possible to solve problems such as damage to the.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a surface potential measuring device for evaluating an optical information recording medium according to the present invention.

FIG. 2 is a diagram showing a surface potential distribution of a substrate.

FIG. 3 is a diagram showing a surface potential distribution of the stamper 1.

FIG. 4 is a diagram showing a surface potential distribution of the stamper 2.

FIG. 5 is a diagram showing a surface potential distribution of the stamper 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Probe for measuring surface potential, 2 ... Surface potential meter, 3 ... Injection molded substrate, 4 ... Metal turntable, 5 ... Electrostatic shield, 6 ... Recorder.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kaoru Teramura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] 1. A method for evaluating an optical information recording medium by an injection molding method, wherein the substrate is evaluated by measuring the surface potential of the substrate. 2. A method for detecting a defect of a substrate by reading a change in reflected light, a transmitted light, a diffracted light and the like due to irradiation of a light source, and a method for detecting a charging state of the substrate by measuring a surface potential, A method for evaluating an optical information recording medium, which comprises evaluating a substrate. 3. A turntable, an injection-molded substrate arranged on the turntable, a movable surface potential measurement probe provided above the injection-molded substrate, and the surface potential measurement probe. An apparatus for evaluating an optical information recording medium, comprising: a surface electrometer for measuring the surface potential of a substrate, wherein the substrate is evaluated by measuring the surface potential of the substrate.