JPH06142951A - Laser marking system - Google Patents

Abstract

PURPOSE:To provide the laser marking system which can shorten a printing time especially, in the laser marking system in which a transmission type liquid crystal is adopted as a mask for intercepting a YAG laser light. CONSTITUTION:In the laser marking system constituted so that a liquid crystal for displaying a pattern is used for a mask, its liquid crystal mask is irradiated with a laser beam, and a transmission laser beam is allowed to pass through an optical system and allowed to reach an object to be worked, and marking is executed to the work to be worked, this system executes control so that an effective voltage value applied to the liquid crystal for allowing the laser beam for executing printing to the object to be worked to transmit through and shielding it is raised for a prescribed time after a display of the liquid crystal is started, and also, lowered to a prescribed voltage after a prescribed time elapses. By boosting the effective voltage value applied to the liquid crystal for a prescribed time after the display is started, and lowering it to a prescribed effective voltage value after a prescribed time elapses, as for a transmission picture element, the displays is raised by a high effective voltage, therefore, the display start time is shortened. Also, a condition until now can be applied as it is without impairing the printing quality.

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 in which a transmissive liquid crystal is used as a mask for blocking YAG laser light, and more particularly to improvement of a laser marking system for shortening printing time.

[0002]

2. Description of the Related Art Conventionally, the present inventors have filed Japanese Patent Application No. 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 the laser beam P1 from the YAG laser oscillator 1 with the optical lens 2 and then deflecting it in the XY directions for raster scanning, and the laser beam reflected by the first deflector 3Y. An optical system 4 for condensing P3 on a point on the 3X deflecting surface of the first deflector P4, and the first deflector 3X, 3
A liquid crystal mask 6 for displaying a pattern for electrically transmitting or scattering the raster scanning light P5 from Y, and second deflectors 7X, 7Y for further deflecting the raster scanning light P6 transmitted through the liquid crystal mask 6 in the XY directions, The laser beam P6 is used so that the raster scanning light P5 reaches one point on the reflecting surface of the second deflector 7X.
An optical system 5 for changing the direction of the image, a work 10 on which the raster scanning light P9 from the second deflectors 7X and 7Y is irradiated, and a pattern is printed on the irradiation portion, and a controller 11.
In the figure, the symbol M indicates a drive motor.

In the above structure, a transmission dispersion type liquid crystal mask is used as the liquid crystal mask, and the liquid crystal mask is provided with a large number of parallel electrode lines on the front and back surfaces of the liquid crystal and so that the front and back surfaces intersect each other. . The liquid crystal in the voltage non-applied portion is in a laser light scattering state, while the liquid crystal in the voltage applied portion is a liquid crystal mask in a laser light transmitting state. Therefore, by utilizing such electrical characteristics, a voltage is selectively applied to the electrodes to instantly image a desired pattern.

[0004]

However, when the printing speed is increased by using the above-mentioned conventional technique, a problem occurs. That is, it was found that the process of switching the display of the liquid crystal mask was not performed instantaneously, and it was 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 printing is performed in this state, printing is started before the liquid crystal display rises, which causes uneven printing on the workpiece. Therefore, there is a limit in maintaining the print quality and increasing the speed.

The present invention pays attention to the above-mentioned conventional problems, and
The present invention relates to a laser marking system that employs a transmissive liquid crystal as a mask that shields G laser light, and particularly aims to provide a laser marking system that shortens the printing time.

[0006]

In order to achieve the above object, according to a first aspect of the present invention, a liquid crystal having a pattern displayed on a mask is used, and the liquid crystal mask is horizontally raster-scanned by a laser beam to obtain a transmission laser. In a laser marking system configured to allow a beam to reach an object to be processed through an optical system and to mark the object, the effective voltage value applied to the liquid crystal that transmits and shields the laser beam for printing on the object The liquid crystal display device is characterized in that the liquid crystal display is controlled to rise for a predetermined time after the liquid crystal starts to be displayed, and to drop to a predetermined voltage after a predetermined time has elapsed.

[0007]

When the liquid crystal switching time is analyzed, it is roughly divided into the time to erase the displayed pattern and the time to start a new display pattern. Of these, the time to erase the displayed pattern depends on the constituent material and structure of the liquid crystal mask, and the time cannot be easily shortened. Therefore, in order to eliminate the above-mentioned difficulties, it is necessary to shorten the display rising time of the liquid crystal. For example, "LCD application (edited by Okano and Kobayashi, published by Baifukan in 1985)"
As described on page 85, the transmittance of liquid crystal is determined by the effective voltage value applied. 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 rise response time of the liquid crystal can be shortened by increasing the effective voltage value applied to the liquid crystal for a short time after the start of display and setting the voltage value such that a predetermined transmittance can be obtained after a certain period of time. When the liquid crystal mask is used, the voltage is applied to the pixel serving as the shutter, so that the shutter pixel also shows transmission when the high effective voltage value is continuously applied. Combined with the fact that the transmittance is 0% at the start of display and that it takes time to change the transmittance of the shutter pixel, the shutter does not penetrate even if a high effective voltage value is applied, and the display of the transparent pixel Start-up can be shortened. And after a certain period of time (specifically,
The transmissive pixel exhibits a sufficient transmissivity, and the shutter pixel does not transmit by lowering the effective voltage value to a predetermined value before the shutter pixel exhibits transmissivity. On the other hand, the transmissive pixel is displayed at a high effective voltage, so
The display startup time is shortened. The present invention described above is
By applying a transmission type liquid crystal to a mask that blocks G laser light, it is possible to apply the existing conditions as they are without impairing the printing quality, and to manufacture a laser marker with a short printing time. It will be possible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a laser marking system according to the present invention will be described in detail below with reference to the drawings. The configuration using the present invention is the same laser marking system as the conventional one proposed by the present inventor shown in FIG. 2, in which the polymer composite type liquid crystal 20 is used as the liquid crystal, and the controller 1
The effective voltage value applied from 1 to the polymer composite liquid crystal 20 is
As shown in FIG. 3, the short time (T1) after the start of display is high (V1), and after a certain time has elapsed (T1) (specifically,
A command value for lowering (V2) to a predetermined effective voltage value is issued at a timing before the transmissive pixel exhibits sufficient transmissivity and the shutter pixel exhibits transmissivity. FIG. 1 shows a response characteristic at the start of display obtained by using this liquid crystal. This data is measured at an environmental temperature of 20 ° C. The liquid crystal drive voltage is 11 Vrms. The drive voltage when the liquid crystal display starts up is measured at 11 Vrms which is the same as the setting, and the voltage which is 10% larger, 12.1 Vrms, is 40%.
It was applied 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 analysis, the transmittance is 0% to 90.
The time required to reach 50% was 35 msec as a result of applying the present invention, which used to take 70 msec in the past.
As a result of using the present invention for a liquid crystal laser marker, unevenness does not occur on the printing surface of a non-processed object even if the printing speed is increased.

[0010]

As described above, according to the present invention,
By raising the effective voltage value applied to the liquid crystal for a predetermined time after the start of display and then lowering it to the predetermined effective voltage value after a certain period of time, the transmissive pixel starts up the display with a high effective voltage. Time is reduced. Further, it is possible to manufacture the laser marker in which the conditions so far can be applied as they are without deteriorating the printing quality and the printing time is shortened.

[Brief description of 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 a relationship between time and effective voltage when the present invention is used.

[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,

Claims (1)

[Claims] 1. A laser having a structure in which a liquid crystal having a pattern displayed on a mask is used, the liquid crystal mask is irradiated with a laser beam, a transmitted laser beam is passed through an optical system to reach a workpiece, and the workpiece is marked. In the marking system, the effective voltage value applied to the liquid crystal that transmits and shields the laser beam for printing on the work piece is increased for a predetermined time after the start of the liquid crystal display, and up to the predetermined voltage after the predetermined time has elapsed. A laser marking system characterized by being controlled so as to be lowered.