JPS63205867A - Magnetic disk inspection method - Google Patents

Abstract

PURPOSE:To inspect the application state of a transparent adhesive by irradiating the applied adhesive with a ray of light comprising ultraviolet light, receiving the ultraviolet light included in the reflected light of the above ray and measuring the intensity of the received ultraviolet light. CONSTITUTION:Ultraviolet light 6 is projected from an ultraviolet light source against the transparent adhesive 4 applied on the top surface of a flange part 2b of a center hub 2 mounted with its magnetic chuck surface 2c upward on a turntable 10. The transparent is irradiated with the ultraviolet light over its whole length by rotating the turntable 10 by 360 deg.. The luminous quantity of the reflected light received by a light receiver 13 capable of sensing ultraviolet light is monitored and a part where the quantity of light is larger than a fixed level of threshold limit value can be detected as the part to which the transparent adhesive did not applied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for inspecting a magnetic disk in which a magnetic disk body and a center hub are bonded together with an adhesive. This relates to an inspection method for making a judgment.

(Prior Art) Conventionally, for example, a magnetic disk housed in a hard case in a 3.5-inch micro-floppy disk has a magnetic layer on its surface, and the magnetic layer is rotated at high speed by a magnetic head. 2. Description of the Related Art Magnetic disks consisting of a flexible disk-shaped magnetic disk body on which magnetic recording and reading are performed and a center hub provided at the center of the body are in widespread use.

An example of such a magnetic disk is shown in FIG.

The illustrated magnetic disk 1 consists of a so-called hat-shaped metal center hub 2 and a magnetic disk body 3.
The flange portion 2b and the inner circumferential edge portion 3b of the magnetic disk body are bonded together using a transparent adhesive. This center hub 2 is for positioning the magnetic disk 1 at a predetermined position, chucking it, and rotationally driving the magnetic disk 1 when it is attached to a magnetic recording/reading device (hereinafter referred to as a driver). The top surface is a magnetic chuck surface 2C, and when the magnetic disk 1 is mounted on the driver, it is magnetically chucked by the attraction magnet of the driver.

The magnetic disk body 3 and the center hub 2 are bonded to each other by uniformly applying a transparent adhesive 4 in a ring shape to the surface of the flange portion 2b of the center hub 2 on the side where the hat portion protrudes, as shown in FIG. However, if air bubbles 4a get mixed into the transparent adhesive coating area as shown in FIG. 7A, or breaks 4b occur in the transparent adhesive coating area as shown in FIG. 7B, the magnetic disk main body 3 may become damaged. The sticking condition becomes uneven and the flatness of the magnetic disk body 3 is impaired, and when the driver is installed and rotated, undulations (waves) occur, and the head hits unevenly, resulting in disturbances in recording signals and erroneous recording during recording. etc. are likely to occur, and even during reproduction, problems such as inaccurate reproduction occur.

Therefore, it is necessary to inspect the state of application of the transparent adhesive 4 to the center hub 2 to ensure a good state of application at all times.

As shown in Fig. 8A, such an inspection technique is as follows.
There is a method in which red (or infrared, laser) light 6 is irradiated from a light source 5 to the area where the adhesive 4 is applied, the reflected light 7 is received by the position sensor 8, and the unapplied area is detected based on the difference in the receiving position. Are known.

In this method, when the light 6 emitted from the light source is irradiated onto the transparent adhesive 4 applied to the flange portion 2b, the reflected light is reflected from the surface of the transparent adhesive 4 as shown by the solid line in FIG. 8B. 7, and the light is received at a certain position of the position sensor 8. However, when the above-mentioned bubble 4a or the transparent adhesive break 4b is irradiated, the light is reflected from the flange portion 2b as shown by the broken line in FIG. 8B. 7', and is received at a different position from the reflected light 7. Therefore, a difference occurs in the position at which the position sensor 8 receives the reflected light. The light 6 is irradiated all around the flange portion 2b, and the position where the transparent adhesive 4 is not applied is detected by sensing the light receiving position with the position sensor 8.

(Problems to be Solved by the Invention) However, in such conventional inspection methods, since the adhesive 4 is transparent, the light 6 is often transmitted through the adhesive surface without being reflected. Therefore, light that would normally be reflected on the surface of the transparent adhesive 4 like the reflected light 7 shown in FIG. 8B passes through the transparent adhesive 4 and
The light often hits the surface and is reflected as reflected light 7'.

For this reason, the S/N ratio was very poor, resulting in many false detections, and it was difficult to accurately inspect the areas to which the transparent adhesive 4 was not applied.

In view of the above problems, an object of the present invention is to
It is an object of the present invention to provide a magnetic disk inspection method that improves N and can stably detect portions to which transparent adhesive is not applied.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a magnetic disk that inspects the application state of a transparent adhesive applied to bond a magnetic disk main body and a center hub. In the inspection method, the coated transparent adhesive is irradiated with a light beam containing ultraviolet light, the ultraviolet light included in the reflected light is received, and the coating state of the adhesive is determined based on the intensity of the received ultraviolet light. It is characterized by inspecting.

(Function) Transparent adhesives commonly used in magnetic disks, such as polyurethane adhesives, vinyl acetate adhesives, polyester adhesives, and cyanoacrylate adhesives, have the property of absorbing ultraviolet light. The center hub also completely reflects ultraviolet light.

(Effects of the Invention) The present invention irradiates a light beam containing ultraviolet light onto a portion coated with a transparent adhesive that adheres a magnetic disk body and a center hub, receives this reflected light, and adjusts the intensity of the reflected light. The coating condition of the transparent adhesive is inspected based on the following criteria. Since the transparent adhesive has the property of absorbing ultraviolet light, the intensity of the reflected light from the adhesive is extremely low, and in areas where the adhesive is not applied due to bubbles or breaks, all the ultraviolet light that hits the center hub is absorbed. Since the light is reflected, the intensity of the reflected light increases. In this way, the intensity of reflected light clearly differs depending on whether transparent adhesive is applied or not, so S/
N improves, and it becomes possible to stably detect areas to which transparent adhesive is not applied.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

As explained in the section of the prior art with reference to FIG. 6 and subsequent figures, the magnetic disk body 3 of the magnetic disk 1 and the center hub 2 are bonded together through the transparent adhesive 4 applied to the flange portion 2b of the center hub 2. . In the present invention, ultraviolet light is used to inspect whether the transparent adhesive 4 is uniformly applied over the entire circumference of the flange portion 2b.

FIG. 1 is a schematic diagram showing an apparatus used to carry out an embodiment of the magnetic disk inspection method according to the present invention.

The optical fiber 12 connected to the ultraviolet light @i11 is applied to the transparent adhesive 4 applied to the upper surface of the flange portion 2b of the center hub 2, which is placed on the rotary table 10 with the magnetic chuck surface 2C facing upward. Ultraviolet light 6 is irradiated from the tip.

By rotating the rotary table 10 360 degrees in a fixed direction, ultraviolet light 6 is irradiated over the entire length of the transparent adhesive 4 on the flange portion 2b, and whether or not it is coated is detected. In other words, the ultraviolet light 6 irradiated onto the transparent adhesive 4
Most of it is absorbed by the transparent adhesive 4, so the amount of reflected light detected by the receiver 13 that detects ultraviolet light is extremely small. 6 is reflected by the flange portion 2b, and is received by the light receiver 13 as a reflected light with high intensity. Therefore, the optical indication of the reflected light received by the light receiver 13 is monitored, and a portion where the optical indication becomes larger than a TH level (threshold value) set at a certain level is detected as an area where transparent adhesive is not applied. Can be done. 7 lunge part 2b on horizontal axis
FIG. 2 shows a graph in which the position on the circumference of , and the output level of the ultraviolet light receiver is plotted on the vertical axis. As shown in this graph, when the intensity of the reflected light becomes higher than a predetermined TH level, the area where the intensity becomes higher is the area where the transparent adhesive is not applied.

FIG. 3 shows another embodiment of the invention. In this embodiment, ultraviolet light 6 is emitted from a light source 20 and irradiated onto the center hub 2 installed with the magnetic chuck 2C facing upward.

As mentioned above, the transparent adhesive 4 applied to the flange part absorbs the ultraviolet light 6, so the light is reflected only in the area where the transparent adhesive 4 is not applied, and the reflected light is transmitted to the ultraviolet light transmitting filter 21 and the ultraviolet light. The light is received by a light receiver 23 comprising a camera 22 with a built-in COD light receiving element that is sensitive to light. The image signal photoelectrically converted by the COD light-receiving element of the camera 22 is input to the image processing unit 24, where it is subjected to threshold processing, and further, the processing result is subjected to predetermined arithmetic processing to judge whether the adhesive application state is good or bad. It is. When the adhesive application state is good, an OK signal is output from the OK signal output terminal 25, and when the above state is poor, an NG signal is output from the NG signal output terminal 26. Note that the image processing section 24
A signal corresponding to the result of the threshold value processing is sent to the monitor 27, so that the adhesive application state can be visually identified. Further, as shown in FIG. 4, the image processing section 24 includes a threshold processing section 28 that sequentially compares the intensity of the input signal with a reference value and performs 2fiEi processing on the image input signal; 28, the area determined to be the adhesive application area, connectivity analysis, etc. are calculated at high speed, and based on the calculation results, the quality of the application state is judged. Depending on the judgment, an OK signal or NG signal is sent. It consists of an image processing section 29 that outputs the image processing section 29, and a CPU 30 that controls the image processing section 29.

Transparent adhesives used in the present invention generally include polyurethane adhesives, vinyl acetate adhesives, polyester adhesives, cyanoacrylate adhesives, and the like. The ultraviolet light transmittance of these adhesives ranges from about 400 nl in the visible range to about 750 nl, as shown in Figure 5.
Since UV light transmittance of No. 1 is extremely high, it is possible to accurately detect areas where transparent adhesive is not applied.

Note that if a xenon stroboscope or the like is used as the ultraviolet light source, it is possible to extend the life of the ultraviolet light source, which is generally considered to have a short life.

In the present invention, the ultraviolet light sources include, for example, a light source that mainly emits the ultraviolet light (light source ■), a light source that emits the ultraviolet light and other light (light source ■), and a light source ■
It is possible to use a Tchinoku light source (■) equipped with an ultraviolet light transmitting filter on the front, and a light receiver that is primarily sensitive to ultraviolet light (receiver ■), which is sensitive to ultraviolet light and other types of light. A light receiver that is sensitive to light (light receiver■
) and a light receiver (2) equipped with an ultraviolet light transmitting filter on the front (light receiver (2)) can be used. However, they must be used in the following combinations.

Light source ■ and receiver ■, ■ or ■ Light source ■ and receiver ■ or ■ Light source ■ and receiver ■, ■ or ■

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of an apparatus used to carry out the magnetic disk inspection method according to the present invention, and FIG. 2 shows reflected light detected in the embodiment of the inspection method shown in FIG. FIG. 3 is a graph showing an example of the optical display, FIG. FIG. 5 is a graph showing the ultraviolet transmittance of the transparent adhesive used in the present invention; FIG. 6 is a perspective view showing the configuration of a general magnetic disk; 7A and 7B are diagrams showing whether the adhesive is applied to the center hub, and FIGS. 8A and 8B are schematic diagrams showing a conventional magnetic disk inspection method. 1... Magnetic disk 2... Center hub 3... Magnetic disk body 4... Transparent adhesive 6... Ultraviolet light 7... Reflected light Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 QIJIJ Qll+ Figure 6 Figure 7A Figure 7B Figure 8A Figure 8B 1

Claims (1)

[Claims] In a magnetic disk inspection method for inspecting the coating state of a transparent adhesive applied to a center hub for bonding a magnetic disk main body and a center hub, the applied transparent adhesive is irradiated with a light beam containing ultraviolet light, and the reflected light is measured. A method for inspecting a magnetic disk, comprising: receiving the ultraviolet light contained in the light, and inspecting the applied state of the adhesive based on the intensity of the received ultraviolet light.