JP2811138B2 - Laser marking device and laser marking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser marking system employing a transmission type liquid crystal as a mask for blocking a YAG laser beam, and more particularly to an improvement in a laser marking system for shortening an engraving time.

[0002]

2. Description of the Related Art Conventionally, the present inventors have filed a Japanese Patent Application No. Hei 3-2249.
No. 16 proposes a laser masking system. In this proposal, as shown in FIG. 2, the YAG laser mask marker is a YAG laser oscillator 1 with a Q switch,
First deflectors 3X and 3Y for converging laser light P1 from a YAG laser oscillator 1 by an optical lens 2 and then deflecting them in the XY directions for raster scanning, and laser light reflected by the first deflector 3Y An optical system 4 for converging P4 at one point in the 3X deflection plane of the first deflector 3;
A liquid crystal mask 6 for displaying a pattern for electrically transmitting or scattering the raster scanning light P5 from Y; second deflectors 7X and 7Y for further deviating the raster scanning light P6 transmitted through the liquid crystal mask 6 in the XY directions; The laser beam P6 is applied so that the raster scanning light P5 reaches one point in the reflection surface of the second deflector 7X.
And the raster scanning light P9 from the second deflectors 7X and 7Y is applied to change the direction of
A work 10 to be engraved and a controller 11 are provided.
In the drawings, the symbol M indicates a drive motor.

In the above configuration, a transmission scattering type liquid crystal mask is used as a liquid crystal mask. This liquid crystal mask is provided such that a number of parallel electrode lines cross each other between the front and back surfaces of the liquid crystal. . The liquid crystal in the portion where no voltage is applied is in a laser light scattering state, whereas the liquid crystal in the voltage application portion is a liquid crystal mask that is in a laser light transmitting state. Therefore, by utilizing such electrical characteristics, a voltage is selectively applied to the electrodes, and a desired pattern is instantaneously imaged.

[0004]

However, a problem has arisen when the speed of engraving is increased by using the above-mentioned prior art. That is, it has been found that the process of switching the display of the liquid crystal mask is not performed instantaneously, and it is necessary to consider the switching time. The length of the switching time is about 60 msec, and this time is required for each pattern switching. When high-speed engraving is performed in this state, the engraving is started before the display of the liquid crystal does not rise, so that the engraving of the workpiece becomes uneven. Therefore, there has been a limit in increasing the speed while maintaining the quality of the marking .

[0005] The present invention focuses on the above-mentioned conventional problems, and YA
The present invention relates to a laser marking system employing a transmission type liquid crystal as a mask for blocking G laser light, and more particularly, to provide a laser marking system for shortening an engraving time.

[0006]

In order to achieve the above object, a laser marking device according to the present invention comprises a laser oscillator.
, Multiplex driven liquid crystal mask, and controller
A laser marking device comprising:
Is applied to the liquid crystal mask when displaying the engraved pattern
The effective voltage value to be greater than the predetermined effective voltage
Start displaying the engraving pattern and apply the engraving pattern to the liquid crystal mask.
After the turn indication is up, the laser oscillator
The liquid crystal mask is irradiated with the light, and the liquid crystal mask rises.
Shutter pixels that make up a sharp engraved pattern display are transmitted
The effective voltage applied to the liquid crystal mask before
It is characterized by performing engraving by lowering the effective voltage.
You. In addition, the laser marking method of the present invention
Laser light emitted from the
Laser that irradiates the liquid crystal mask through the liquid crystal mask
In laser marking method that irradiates the work with light
The effective voltage value applied to the liquid crystal mask to a predetermined effective value.
Displaying the engraved pattern as a value greater than the voltage
And the display of the engraved pattern on the liquid crystal mask rises
Irradiating a laser beam after the engraving, and the liquid crystal
The mask that constitutes the engraved pattern display that has risen on the mask
Before applying the liquid crystal mask before the
Lowering the effective voltage value to a predetermined effective voltage.
It is characterized by.

[0007]

When the liquid crystal switching time is analyzed, it is roughly divided into a time for erasing a displayed pattern and a time for starting a new display pattern. The time for erasing the displayed pattern depends on the constituent materials and structure of the liquid crystal mask, and the time cannot be easily reduced. Therefore, in order to solve the above-mentioned difficulty, it is necessary to shorten the display rise time of the liquid crystal. For example, "Liquid Crystal Application Edition (by Okano and Kobayashi, edited by Baifukan 1985)"
As described on page 85, the transmittance of the liquid crystal is determined by the applied effective voltage value. Here, the effective voltage is defined by Equation 1.

(Equation 1) In Equation 1, V is the applied voltage waveform, and T is the period of the applied voltage waveform. Therefore, the effective voltage value applied to the liquid crystal is set higher than a predetermined voltage for a short time after the start of display, and is set to a voltage value at which a predetermined transmittance can be obtained after a certain period of time, thereby shortening the response time of the liquid crystal. be able to. When a liquid crystal mask is used, a voltage is also applied to a pixel serving as a shutter. Therefore, if a high effective voltage value is continuously applied, the shutter pixel also shows transmission. That is, multiple
In a liquid crystal mask driven by a liquid crystal display, the transmittance is almost 0% at the start of display, and it takes time to change the transmittance of the shutter pixels. In this case, it is possible to shorten the rise of the display of the transmissive pixel. After a lapse of a predetermined time (specifically, at a timing before the transmissive pixel shows sufficient transmittance and before the shutter pixel shows transmissivity), the shutter pixel is transmitted by lowering to a predetermined effective voltage value. There is no. On the other hand, since the display of the transmissive pixel starts at a high effective voltage, the display start-up time is shortened. By applying the present invention to a transmission type liquid crystal as a mask for blocking a YAG laser beam, it is possible to apply the conventional conditions as it is without deteriorating the engraving quality, and to shorten the engraving time. It becomes possible to manufacture a laser marker.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a laser marking system according to the present invention will be described below in detail with reference to the drawings. The configuration using the present invention is the same laser marking system as the conventional one proposed by the inventor shown in FIG. 2, in which a polymer composite liquid crystal 20 is used as a liquid crystal, and a controller 1 is used.
The effective voltage value applied to the polymer composite liquid crystal 20 from 1 is
As shown in FIG. 3, the short time (T1) after the start of the display is increased (V1), and after a lapse of a certain time (T1) (specifically,
At a timing before the transmissive pixel shows sufficient transmissivity and the shutter pixel shows transmissivity), a command value for lowering (V2) to a predetermined effective voltage value is issued. FIG. 1 shows the response characteristics at the start of display using this liquid crystal. This data was measured at an ambient temperature of 20 ° C. The liquid crystal drive voltage is 11 Vrms. The drive voltage at the time of rising of the liquid crystal display was measured at 11 Vrms, which is the same as the setting, and the drive voltage at 12.1 Vrms, which is 10% larger, was 40%.
This was given for msec, and then compared with that of 11 Vrms.

As shown in FIG. 1, the time required for startup is reduced. As a result of the analysis, the transmittance was from 0% to 90%.
The time required to reach% was conventionally 70 msec, but as a result of applying the present invention, it became 35 msec.
As a result of using the present invention for a liquid crystal laser marker, no unevenness is generated on the marking surface of the non-processed object even when the printing speed is increased.

[0010]

As described above, according to the present invention,
The effective voltage applied to the multiplex-driven liquid crystal is increased for a predetermined time after the start of display, and the shutter pixel
By lowering to a predetermined effective voltage value before transmitting , the display of the transmissive pixel starts at a high effective voltage,
Display start-up time is reduced and shutter pixels are transparent
The contrast of the inscription becomes clear because it is not performed. That is,
It is possible to apply a conventional condition as it is without deteriorating the marking quality, and to manufacture a laser marker with a reduced marking time.

[Brief description of the drawings]

FIG. 1 is a diagram showing response characteristics of liquid crystals of the present invention and a conventional example.

FIG. 2 is an overall configuration diagram showing an embodiment of a laser marking system using the present invention.

FIG. 3 is a diagram showing the relationship between time and effective voltage using the present invention.

[Explanation of symbols]

 1 YAG laser oscillator, 2 optical lens, 3X, 3Y first deflector, 4, 5, 8 optical system, 7X, 7Y second deflector, 10 work, 11 controller, 20 polymer composite liquid crystal,

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-187287 (JP, A) JP-A-3-22219 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 26/00 G02F 1/133 G02F 1/13

Claims (2)

(57) [Claims] 1. A laser marking device comprising a laser oscillator, a multiplex-driven liquid crystal mask, and a controller, wherein the controller applies an effective voltage to the liquid crystal mask when displaying an engraved pattern. Start the display of the engraved pattern as a value larger than the predetermined effective voltage, and after irradiating the engraved pattern on the liquid crystal mask, irradiate the liquid crystal mask with laser light from a laser oscillator. A laser marking apparatus characterized in that an effective voltage applied to the liquid crystal mask is reduced to a predetermined effective voltage before a shutter pixel constituting a display indicates transmission , and the marking is executed. 2. A laser marking method for irradiating a multiplex-driven liquid crystal mask with a laser beam emitted from a laser oscillator and irradiating a laser beam transmitted through the liquid crystal mask to a workpiece, wherein the laser beam is applied to the liquid crystal mask. Displaying the engraved pattern as an effective voltage value to be greater than a predetermined effective voltage,
A step of irradiating a laser beam after the display of the engraved pattern on the liquid crystal mask to perform engraving, and applying the laser light to the liquid crystal mask before the shutter pixels constituting the engraved pattern display raised on the liquid crystal mask show transmission. Lowering the effective voltage value to a predetermined effective voltage.