JPH01249488A - Marking method - Google Patents

Abstract

PURPOSE:To enable a discriminable mark to be provided extremely easily and speedily, by providing a light-absorptive layer having excellent light absorptivity on a surface of an object, and converting the energy of laser light into heat by the light-absorptive layer to thereby melt the surface of the object. CONSTITUTION:A light-shielding mask 3 having a light-transmitting part 3c in a predetermined pattern is produced, and a light-absorptive layer 2 is provided on a surface of an object 1 in a region to be marked. The mask 3 is disposed between the object 1 and a light source 4, and a pulse of electric current is supplied to the light source 4 a predetermined number of times, whereby laser light is emitted from the light source 4. The light is reflected in area corresponding to a chromium film 3b of the mask 3, whereas in an area corresponding to the light-transmitting part 3c, the light is absorbed into the light-absorptive layer 2, and is converted into thermal energy. The thermal energy is transmitted from the light-absorptive layer 2 to the surface of the object 1 making close contact with the layer 2, thereby melting the surface of the object 1. By regulating the number of times the pulse of current is supplied, it is possible to provide a mark having a required depth.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a marking method, for example, a method for inconspicuously attaching a desired marking to the surface of an eyeglass lens or other lens or a translucent member. It is.

[Prior Art] For example, spectacle lenses and the like are marked with marks for the purpose of distinguishing between one's own products and those of other companies, or indicating model numbers, specifications, specific position instructions, and the like.

In this case, due to the nature of the product, eyeglass lenses, the above mark is required to be as inconspicuous as possible, so it is normally impossible to recognize it with the naked eye, and if necessary (
For example, so-called hidden marks are attached that can be recognized (by observing from a specific angle).

Conventionally, the most common marking method for creating such hidden marks has been engraving with a needle made of a hard material such as diamond.

However, marking by engraving is performed by moving a tool along a predetermined marking pattern, which is inefficient and requires a significant amount of time to mark, and it is difficult to apply the same pattern to many objects. There is a problem of poor reproducibility when doing so. Furthermore, due to the engraving using a sharp object such as a needle, the marking part on the surface of the an lens 1 becomes a V-groove shape as shown in FIG. There was also the problem that the state of light reflection was different from that of other parts, resulting in insufficient performance as a hidden mark.

For this reason, in recent years, a light-shielding mask is used that has a light-transmitting part that follows the pattern of the mark to be marked, and the surface of the object to be marked is irradiated with laser light through the mask. Attempts have been made to create a mark by melting the surface of the object along the pattern of the mark using the heat absorbed and generated by the object.

[Problems to be Solved by the Invention] However, although the conventional marking method using laser beam irradiation is excellent in work efficiency, reproducibility of mark patterns, etc., it has the following serious drawbacks.

That is, the marks made by the above method generally
It tends to become noticeable under normal usage conditions (that is, it tends to take on the shape shown in FIG. 5).
On the other hand, when trying to make the marks less noticeable, there was a marked tendency for the marks to become almost impossible to distinguish. For this reason, various efforts have been made to form marks that are inconspicuous during normal use and can be identified when necessary, but in the end, the only way to do so is to precisely set the intensity of the laser beam to the optimum intensity. There is no valid plaintext,
Moreover, it is extremely difficult to find this optimal strength, and fi3i! Even if the conditions for The disadvantage was that it was not possible to make precise markings.

In addition, laser equipment that can be applied to this method must have a wavelength that allows processing of transparent materials to a certain extent, so the number of laser equipment that can be applied to this method is extremely limited. A C02 laser has been used, but this laser device has the drawbacks of being generally expensive and complicated to handle.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a marking method that can realize a marking that can reliably function as a hidden mark with good reproducibility.

[Means for Solving the Problems] The present invention has been made based on the knowledge obtained as a result of various studies of the conventional marking methods using laser light by the present inventors.

That is, according to the findings of the present inventors, the principle of marking in the conventional method is to directly absorb the laser beam into the object itself, and melt the object with the heat generated at that time, thereby marking the mark. It is attached.

However, the target object is usually a translucent member, and even if the wavelength of the laser beam is selected to have certain absorption characteristics for the target object, a considerable portion of the irradiated laser light will It cannot be denied that there is a strong tendency for the particles to be absorbed after advancing inside the object. For this reason, irradiation with laser light tends to melt the inside.
It is thought that the mark that was obtained in the end would have been conspicuous. Of course, it is conceivable that a desired mark may be obtained under certain optimal conditions, but it is conceivable that these conditions are limited to an extremely narrow range.

Based on this knowledge, the present inventors, in the process of exploring whether there is a method of applying the necessary amount of thermal energy only to the surface of the object to be marked, but not to the inside, We arrived at the idea that there is a limit in principle to the traditional method of directly absorbing laser light into an object and melting it, as long as the laser light travels inside and is absorbed. As a way to avoid this, a different principle from the above principle is used: forming a light absorption layer with excellent light absorption on the surface of the object, converting the energy of the laser beam into heat with this member, and using this heat to He came up with the principle of melting the surface of objects.

The present invention is based on such a principle and has the following configuration.

A light absorbing layer is provided on the surface of at least the area to be marked on the object to be marked, and the light absorbing layer is heated through a light shielding mask having a light transmitting portion along a pattern corresponding to the mark to be formed. A marking method characterized in that a mark is attached to the surface of the object by irradiating with.

[Function] According to the above configuration, the light absorption layer on the surface of the object generates heat by irradiation with the laser beam, and this heat is transferred to the surface of the object, so that the object melts from the surface in a predetermined pattern. be done.

In this case, the distance that the heat transferred to the object can reach inward in the thickness direction of the object is extremely limited because the object is generally thermally insulating. This is significantly smaller than the range in which the irradiated laser beam advances to the object, which is a transparent member, is absorbed, and is converted into heat, thereby melting it, as in the conventional method.

Only the surface part is melted faithfully to the pattern of the mark,
This makes it possible to attach a mark that is extremely inconspicuous but can be identified if necessary.

Furthermore, since the light absorption layer can be selected almost independently of the material of the object to be marked, by selecting the material of the light absorption layer, it is possible to freely select a laser device for any wavelength. Moreover, it is therefore possible to precisely set the intensity of the laser beam to be irradiated to a desired intensity and to select a relatively inexpensive laser device, and furthermore, it is possible to make good marks.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

First, the apparatus used to carry out the method of the present invention will be explained with reference to FIGS. 1 and 2. Reference numeral 1 indicates a spectacle lens as a marking target, and reference numeral 2 indicates a light absorption layer formed on the surface of the spectacle lens. Code 3 is a light-shielding mask, 4 is YA
This is a G laser light source.

The light absorption layer 2 is made of, for example, a black paint such as drafting ink or enamel paint, and has a function of effectively absorbing laser light according to the wavelength of the irradiated laser light. In general, if the material is recognized as black with the naked eye, it can effectively absorb light with respect to laser light having a wavelength of 0.5 μm or more. In this case, it goes without saying that it is preferable to use a material that has as high an absorption rate as possible for the wavelength of the laser light to be irradiated.

The light-shielding mask 3 is made by providing chromium 1113b on a transparent substrate 3a made of glass by a method such as sputtering, and by etching this chromium film 3b, marks such as letters and figures are formed as shown in FIG. It has a structure in which a light transmitting portion 3c is formed in a shape corresponding to a pattern. Note that the remaining chromium film 3b is removed from the light transmitting part 3.
It functions as a light shielding part that blocks light other than C from passing through.

The light source 4 is a YAG laser irradiation device, and is driven by a pulsed current so as to be able to intermittently irradiate a beam of light.

Marking using the above-described apparatus is performed according to the following steps.

a. A light-shielding mask 3 having a predetermined pattern of light-transmitting portions 3C is manufactured.

b. Before and after the above step a, a light absorption layer 2 is formed on the surface of the object 1 in an area where marking is to be applied.

C1 After the above steps a and b are completed, a light-shielding mask 3 is placed between the object 1 and the light source 4 as shown in FIG.

d. After the above step C is completed, when a predetermined number of pulse currents are supplied to the light source 4, the laser light is irradiated as shown by the arrow, and the light is emitted at the part of the light-shielding mask 3 corresponding to the chromium film 3b. After being reflected, the light is transmitted through a portion corresponding to the light transmitting portion 3C and reaches the surface of the object 1, where it is absorbed by the light absorption layer 2 and converted into thermal energy. This thermal energy is transmitted from the light absorbing material 2 to the surface of the object 1 that is in close contact with it, and melts the surface of the object 1 (part of it is gasified by the high heat). Then, by adjusting the number of times the pulse current is supplied, it is possible to make a mark of the required depth.

e. When the light absorbing material 2 on the surface of the object 1 is removed, the marking work is completed, and a large and shallow trough 5 is formed as a marking, as shown in FIG.

According to the embodiment described above, there are the following advantages.

That is, the heat transferred to the object 1 is transferred to the object'! J
Since the object 1 is generally thermally insulating, the distance that can be reached toward the inside in the thickness direction of the AL is extremely limited, and the distance that can be reached inward in the thickness direction of the AL is extremely limited. This is significantly smaller than the range in which the laser beam travels to the object 1, which is a transparent member, is absorbed, is converted into heat, and melts the object.

Therefore, only the surface portion of the object 1 that is in contact with the light absorption layer 2 is melted faithfully to the pattern of the mark, thereby making it possible to attach a mark that is extremely inconspicuous but can be identified if necessary.

Moreover, as the light absorption layer 2, an extremely easily available material such as drafting ink is used, and the laser device is a YAG laser, which is relatively inexpensive and easy to handle, and uses a pulse oscillation method. Therefore, by changing the number of times the pulsed light is irradiated by this pulse oscillation, the total intensity of the light irradiated onto the object can be precisely set to a desired intensity, making it possible to make an extremely good mark.

The present inventors have conducted various experiments in order to actually confirm the method of the above embodiment, and some of the results are listed below as experimental examples.

Experimental Example 1 Object: Plastic lens for eyeglasses Light absorbing material: Black ink for drafting (Rotring's AR
T-591017) was applied to the surface of the object using a polyethylene brush and dried at 25°C for 10 minutes.

Light source: A YAG laser with an output of 260 mJ was driven by a pulsed current.

Light-shielding mask: A transparent glass substrate with chromium sputtered and etched.

After irradiating the laser beam several times under the above conditions, we wiped off the light absorbing material with a cleaning vapor impregnated with ethyl alcohol and checked the marking state.
We were able to apply markings that are inconspicuous under normal conditions but can only be confirmed by the difference in reflected light.

Experimental Example 2 The marking target was a glass lens for glasses and silicate glass, and considering the difference in material from the case of Experimental Example 1,
Similar masking could be achieved in an experiment where the laser output was 330 mJ and other conditions were the same.

Experimental Example 3 Furthermore, an experiment was conducted to clarify the relationship between the number of laser irradiations and the marking depth.

Target object: Plastic lenses for eyeglasses (CR-
Laser: Pulse-driven YAG laser output Kerr 1, I It was confirmed that there is a linear relationship between marking depth. Therefore, by controlling the number of irradiations, marking at various depths using the same device, or adjusting the irradiation amount depending on the material of the object (plastic or glass), it is possible to achieve a predetermined mark. Depth marking can be done.

Note that the present invention is not limited to the above embodiments,
For example, the object to be marked may be an eyeglass glass or plastic lens with an IN film formed on its surface, and the present invention is not necessarily an eyeglass lens, but can also be applied to other items that require similar markings.

Further, the laser device used may be a laser device other than a YAG laser device, and does not necessarily have to be of a pulse oscillation type.

[Effects of the Invention] As detailed above, the present invention forms a light absorption layer with excellent light absorption on the surface of an object, converts the energy of laser light into heat by this light absorption layer, and converts the energy of the laser beam into heat. A mark is attached to the surface of the object by melting the surface of the object, and this makes it possible to attach a mark that is very shallow and inconspicuous, but can be identified if necessary, very easily and quickly. This is what made it possible.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention,
Fig. 1 is a side view showing the arrangement of equipment constituting a marking device to which the method of the present invention is applied, Fig. 2 is a perspective view of a light-shielding mask, Fig. 3 is an enlarged sectional view of the marking part, and Fig. 4 5 is a chart showing the relationship between the number of laser irradiations and the depth of marking, and FIG. 5 is an enlarged sectional view of a marking portion formed by a conventional method. 1... Glasses lens, (object) 5.3...
...Light-shielding mask, 3a...Transparent substrate, 3b...Chromium film (light-shielding material), 3c...
・Light transmission part, 4... Laser light source.

Claims (1)

[Claims] A light-absorbing layer is provided on at least the region to be marked on the surface of the object to be marked, and a laser beam is applied to the light-absorbing layer through a light-shielding mask having a light-transmitting part along a pattern corresponding to the mark to be formed. A marking method characterized by attaching a mark to the surface of the object by irradiating it with light.