JPH05127366A - Halftone pattern forming device - Google Patents

Abstract

(57) [Summary] [Object] To provide a halftone pattern forming apparatus capable of forming a halftone pattern even by using a light source that cannot be directly modulated. [Structure] An XY stage 10 on which a substrate 20 having a halftone screen 22 mounted thereon is mounted, a light source 1 for diverging a light beam, and a light beam focused on the upper surface of the substrate 20 via a halftone screen 22. The objective lens 8 that is exposed to light, the stepping motor 12 that relatively drives the light beam condensed by the objective lens 8 and the XY stage 10, and the control device 1 that controls the motor 12.
8 is provided, and the motor 12 is controlled based on the gradation information of the image so that the exposure amount is adjusted by changing the driving speed relative to the light beam and the XY stage 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a halftone density distribution pattern (halftone pattern) on a substrate coated with a photosensitizer by using a halftone screen used for photographic printing or a dark filter. Halftone pattern forming apparatus.

[0002]

2. Description of the Related Art As a method of expressing the gradation of a gradation image, there is a halftone method in which a gradation image is divided into minute elements and the ratio of black and white in the minute elements is expressed by the density of halftone dots. To form an image by the halftone method, that is, a halftone pattern, a halftone screen 32 is placed on a photosensitive substrate 30 as shown in FIG.
The photosensitive substrate 30 is exposed by scanning the light beam 34 which is formed according to the gradation information of the image and whose intensity is modulated by the control device 35. The halftone screen 32 is made of a photographic film on which a uniform halftone dot density distribution pattern is formed. The halftone screen 32 and the intensity of the irradiation light
The size of the dot pattern formed on the photosensitive substrate is different.

[0003]

The intensity modulation of the light beam is usually performed by modulating the current or voltage applied to the light source. However, an ultraviolet light source used when a resist is used as a photosensitizer has poor linearity of light quantity with respect to applied voltage and stability of the light source below a rated voltage, and cannot be directly modulated. Therefore, it is an object of the present invention to provide a halftone pattern forming apparatus that can form a halftone pattern even if a light source that cannot be directly modulated is used.

[0004]

Therefore, a halftone pattern forming apparatus according to the present invention includes a mounting table for mounting an irradiation object having an irradiation surface and having a halftone screen mounted on the irradiation surface. A light source that diverges a light beam with a predetermined amount of light; a condensing optical system that condenses the light beam of the light source onto the irradiated surface through the halftone screen and exposes the irradiated surface; and The optical system includes a driving unit that relatively drives the light beam condensed by the optical optical system and the mounting table, and a control unit that controls the driving unit. The driving means is controlled based on the gradation information of the image so that the exposure amount is adjusted by changing the driving speed relative to the mounting table.

[0005]

The function of the halftone pattern depends on the exposure amount of the light incident on the halftone screen, and during exposure (the light beam on the object to be irradiated is slightly shifted in a direction perpendicular to the scanning direction, and linear scanning is performed). Then, the scanning speed (V _k ) of the light beam on the object to be irradiated is changed while the light amount (I) is constant, and the exposure amount (D _k = I * V _k ) is controlled.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a halftone pattern forming apparatus according to the present invention will be specifically described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 indicates a light source. Below the light source 1, an attenuator 2 for adjusting the amount of light is installed. Below the attenuator 2, a shutter 4 for blocking the light beam from the light source 1 is provided. The shutter 4 is opened and closed by a shutter drive mechanism 6. The shutter drive mechanism 6 includes a control device 18 described later.
The control device 18 controls opening / closing of the shutter 4. Below the shutter 4, an objective lens 8 which is a condensing optical system is installed.

Below the objective lens 8, an XY stage 10 which is a mounting table is arranged. Two stepping motors 12 for the X-axis and the Y-axis are attached to the XY stage 10, and they are respectively driven in the X-axis direction and the Y-axis direction. As a result, the XY stage 10 can move the object placed on the stage 10 along the X and Y axes, respectively. The Y-axis stepping motor is not shown in FIG. 1 for simplification. These stepping motors 12 are electrically connected to a control device 18 via a driver 14 and a motor controller 16, and are controlled by the control device 18.

On the XY stage 10, a substrate 20 such as glass, which is an object to be irradiated and whose upper surface constitutes the surface to be irradiated, is attached. A photosensitizer is applied to the upper surface of the substrate 20. Further, on the upper surface of the substrate 20, a halftone screen 22 made of a photographic film on which a halftone dot-like density distribution pattern is formed is provided so as to be in close contact with the substrate 20. A transparent plate 24 is provided on the upper surface of the halftone screen 22 to enhance the adhesion between the halftone screen 22 and the substrate 20. The substrate 20, the halftone screen 22, and the transparent plate 24 are fixed to the XY stage 10 by supporting members 25 at both end portions. The operation of the halftone pattern forming apparatus configured as described above will be described below.

First, the shutter 4 includes a shutter drive mechanism 6
Be opened by. After passing through the attenuator 2, the light beam from the light source 1 is focused on one point on the upper surface of the substrate 20 by the objective lens 8 via the transparent plate 24 and the halftone screen 22. This condensed substrate 2
The position of the light beam on 0 is indicated by point SA in FIG. 2 (start point S
A). After that, as shown in FIG.
By driving (shown in FIG. 1) the light beam 26
To the end point EA in the direction along the X-axis in the figure (hereinafter,
Linear movement (SA → EA) in the X-axis direction).
Then, after driving the XY stage 10 to linearly move the light beam 26 toward the starting point SB in the Y-axis direction, the end point E
A straight line is again moved in the X-axis direction toward SB (SB → EB). This operation is performed over the entire exposure area on the substrate 20 (shown in FIG. 1).

When the light beam is moved in the X-axis direction, the shutter 4 (shown in FIG. 1) is opened for exposure, but the light beam is moved in the Y-axis direction, that is, from the end point to the start point. During the movement, the shutter 4 (shown in FIG. 1) is closed and the exposure is not performed. Further, the pitch of the light beam 26 in the Y-axis direction (for example, the distance between the straight line SB / EB and the straight line SC / EC in the Y-axis direction) is about half the diameter of the light beam 26 or less, and the light beam 26 moves in the adjacent X-direction. The amount of light in the area sandwiched between them is made uniform. On the other hand, when the light beam is moved in the X-axis direction, the exposure amount distribution is generated by changing the moving speed of the light beam depending on the place while keeping the light amount constant. _Dk = I / _Vk ... (1) _Dk ... exposure amount, I ... light amount, _Vk ... light beam moving speed

The moving speed of the light beam depends on the rotating speed of the stepping motor which drives the XY stage. Since the rotation speed of the stepping motor can be set only with discrete values, the exposure amount distribution (FIG. 3A) is previously discretized and divided to obtain coordinate data and exposure amount data (see FIG. 3).
From the formulas (B)) and (1), the exposure amount data (D _k ) is converted into the moving speed (V _k ) of the light beam. And this V _k
The rotation speed of the stepping motor is set to correspond to. Here, since the rotation speed of the stepping motor can take only discretized values, if the speed setting value of the stepping motor does not exist, the one with the smallest deviation is selected.

The manner of exposure when the exposure amount distribution is provided in this manner will be described with reference to FIG. When the light beam moves in the X-axis direction and crosses three exposure regions I, II and III in which the regions are divided and different exposure amounts are set, the movement in the X-axis direction starting from the starting point PC ₁ is taken as an example. Then, the speed between PC ₁ and PC ₂ is V ₁ corresponding to the exposure amount of area I, the speed between PC ₂ and PC ₃ is V ₂ corresponding to the exposure amount of area II, and the speed between PC ₃ and PC ₄ is again. Move at speed V ₁ . Therefore, in actual control, the position of the start point and end point of each line, the position of the intersection of the different exposure amount area and that line, and the rotation speed of the pulse motor that determines the exposure amount are determined from the control device to the motor controller at any time. Just enter it.

[0014]

According to the present invention, when forming a halftone pattern, it is possible to directly generate a halftone pattern by generating pattern data on a computer without making a transparent original image.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a halftone pattern forming apparatus according to the present invention.

FIG. 2 is a top view showing a trajectory of a light beam on a substrate.

FIG. 3 includes (A) and (B), (A) is a graph showing distributed exposure data, and (B) is data obtained by discretizing and dividing the data shown in (A). It is a graph shown.

FIG. 4 is a top view showing exposure regions on a substrate in which different exposure amounts are defined.

FIG. 5 is a side view showing a conventional halftone pattern forming apparatus.

[Explanation of symbols]

1 ... Light source, 8 ... Objective lens, 10 ... XY stage, 12
... Stepping motor, 18 ... Control device, 20 ... Substrate,
22 ... Halftone screen, 26 ... Light beam.

Claims (1)

[Claims] 1. A mounting table for mounting an irradiation object having an irradiation surface and having a halftone screen mounted on the irradiation surface, a light source for diverging a light beam with a predetermined light amount, and the halftone. A focusing optical system that focuses the light beam of the light source on the illuminated surface through a screen to expose the illuminated surface, a light beam focused by the focusing optical system, and the mounting table. In a halftone pattern forming apparatus including a driving unit that relatively drives and a control unit that controls the driving unit, the control unit changes a relative driving speed between the light beam and the mounting table. A halftone pattern forming apparatus, characterized in that the driving means is controlled on the basis of gradation information of an image so as to adjust the exposure amount according to.