JPH0244276Y2 - - Google Patents

Description

[Detailed explanation of the invention] Industrial application field This invention uses a point light source such as an ultra-high pressure mercury lamp or a xenon lamp, and after condensing this light with a mirror, the photosensitive plate is exposed to light using a lens. Regarding equipment.

Such devices are mainly used for photoetching and exposing printed circuit boards.

Prior Art In this type of device, in order to effectively utilize the light emitted from the lamp, the light emitting center of the lamp is placed at one focal point of an elliptical mirror that surrounds at least half of the lamp, and multiple mirrors placed near the other focal points are placed. The light is focused onto an integrator consisting of a convex lens, and the convex lens constituting the integrator projects the light multiple times onto the exposure surface, thereby making the irradiation intensity on the exposure surface as uniform as possible.

Problems to be Solved Generally, the luminous intensity of the lamp used is strong in the direction perpendicular to the central axis of the lamp, and the light distribution cross section in the perpendicular direction is circular. Further, the elliptical mirror is usually mounted so that its central axis coincides with the central axis of the lamp, and the cross section of the mirror in the direction perpendicular to the central axis is circular. Therefore, circular light is focused on the integrator, and the intensity distribution irradiated onto the exposure surface from this light also becomes approximately circular. On the other hand, since the photosensitive plate placed on the exposure surface is rectangular or square,
If a photosensitive plate with small dimensions is used, the irradiated light from the lamp cannot be used effectively, and if a photosensitive plate with large dimensions is used, the irradiation intensity at the four corners will be insufficient.

Means for Solving the Problems This invention effectively irradiates a rectangular or square exposure surface with circular light that has been focused on an integrator by a mirror, and is focused on an integrator made up of multiple lenses. In systems where light from a light source is focused by a mirror and the incident angle of each lens is projected onto a rectangular or square exposure surface overlappingly, two or more types of hemispherical lenses with different radii of curvature are used in the integrator, and the peripheral A lens with a radius of curvature of at least 1.2 times that of the hemispherical lens in the other part is combined with a part of the hemispherical lens located in the part, and the number of lenses is less than 1/2 of the total number of lenses.

Embodiments Hereinafter, the present invention will be explained based on the drawings. In FIG. 1, reference numeral 1 indicates a point light source such as an ultra-high pressure mercury lamp or a xenon lamp used as a point light source, and the central axis of the lamp is placed in the X-Y direction in the figure. The lamps used are generally 500 watts to 5000 watts and have a light emitting length of 3 to 15 mm.

Light from the light emission center O of the lamp is most intensely emitted in the OZ direction, and the light reflected by the elliptical mirror 2 is focused on one surface of the integrator 3. The integrator 3 is composed of a plurality of convex lenses, and the projection light from each lens is diffused and irradiated onto the exposure surface 6 in duplicate. In the present invention, two or more types of hemispherical lenses with different radii of curvature are used in the integrator 3, and the radius of curvature of a portion 4, 4' of the hemispherical lens located at the periphery is set to the radius of curvature of the hemispherical lens 5 of the other portion. , 5'... are combined with lenses whose radius of curvature is 1.2 times or more, and the number of lenses is less than 1/2 of the total number.

Figure 2 is a diagram schematically representing the light incident on the integrator 3, the light diffused from this through a convex lens, and projected onto the exposure surface, where P and Q on the integrator are the periphery and center, respectively. Shows light incident nearby. Further, 7 indicates the strongest circle formed on the integrator by the light directed from the lamp in the O-Z direction and reflected by the mirror.

When using the rectangular integrator shown in FIG. 2, when the highest intensity circle is inscribed in the outer frame 8 or slightly inside the outer frame, the amount of light projected onto the exposure surface becomes maximum. Light P incident on the periphery is projected onto R on the exposure surface, and light Q incident near the center is projected onto S on the exposure surface. If the radius of curvature of the convex lens used at the periphery is larger than the radius of curvature of the convex lens used near the center, the concentric circle indicating the irradiation intensity distribution will be smaller than S at R on the exposure surface, and if P and Q are the same incident intensity, R The peak intensity value at is larger than S and is approximately proportional to the radius of curvature ratio of the lens.

3 and 4 show examples of two types of hemispherical convex lenses used in combination with the integrator in the present invention.

The lens of FIG. 3 has a radius of curvature r, and the lens of FIG. 4 has a radius of curvature r'. In this invention, r is
1.2 times or more of r′ is used. In this example, the cross-sectional shape of the lenses was a square that could be easily assembled, and 64 quartz lenses each having a side of 6 mm and a thickness of 6 mm were used.

Figure 5 shows an example of an integrator used in the device of the present invention, which is composed of 64 lenses, with 24 lenses having a large radius of curvature (double circles).
The lenses are placed outside the strongest strength circle on the integrator at the four diagonal corners of the integrator, and the rest have small radius of curvature (single circle mark).

The light projected by the Lens-Ro irradiates the exposure surface in concentric circles with maximum intensity at the center, while the light projected by the Lens-I irradiates the R, T, U, and V portions on the exposure surface as shown in FIG. If the number and position of the lenses are appropriate, the maximum irradiation intensity will occur at the R, T, U, and V parts, and this intensity will approach the maximum value at the center due to the lenses, so it will be especially difficult to reach the four corners of a square exposed surface. The difference in strength at the center is reduced.

If the number of lenses is more than 1/2 of the total number, it will not be possible to combine the lenses in an appropriate arrangement, so there will be no effect of changing the radius of curvature between lenses and b, and if the number of lenses is more than 1/10 of the total number. If the amount is less, the effect of using Lensui will be lost. Furthermore, in order to obtain the maximum strength at the periphery due to Lensui, the radius of curvature r should be
It is necessary to increase the number by 1.2 times, and by doing so, the loss of irradiation to the outside of the square exposure surface will also be reduced.

In one example, when r is 1.3 times r′,
At the exposure surface 6 located 2.2 m away from the integrator 7 in FIG. 2, the intensity distribution on the 500 mm x 500 mm square photosensitive plate was 85%. On the other hand, when r was made equal to r', the intensity distribution on the photosensitive plate decreased to 72% under the same conditions.

Figure 6 shows a reference example of the lens arrangement of an integrator using 64 lenses. 40 lenses with a large radius of curvature (double circles) are arranged outside the center of the integrator, and the rest are lens lenses (single circles). )24
They are arranged.

Since all the lenses in the center are located inside the circle of highest intensity, the amount of light projected by them is small, and the light projected by the lenses placed on and inside the circle of highest intensity also illuminates the center, resulting in a large amount of light. As a result, the intensity distribution deteriorates.

In this reference example, when r is 1.3 times r', the intensity distribution on the 500 mm x 500 mm square photosensitive plate at the exposure surface 2.2 m away was 75%.

In another embodiment, two types of lenses with curvature radii r1 and r2 are used, r1 is 1.25 times r', and r
2 can be set to 1.35 times r' to make the adjustment of the intensity distribution even narrower. In addition, in the above embodiment, the integrator lens combined into a square shape and the square exposure surface were explained, but the same effect can be obtained even if the integrator lens has an octagonal shape or an approximate circular shape, a rectangular shape, etc. The combination shape or arrangement is a rectangle,
Making the structure vertically and horizontally asymmetric has the advantage that it can be adapted to a rectangular exposure surface.

Effects of the invention As mentioned above, in the device of the present invention, the distribution of irradiation intensity is uniform on the rectangular or square exposure surface, and the irradiation light is effectively used within the exposure surface, reducing the loss of light to areas other than the exposure surface. can be minimized.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the configuration of the irradiation device with an integrator of the present invention, Figure 2 is a schematic diagram showing the light incident on the integrator and the spot light projected onto the exposure surface, and Figure 3 is a hemispherical surface with a large radius of curvature. FIG. 4 is a side view of a hemispherical lens with a small radius of curvature. FIG. 5 is a diagram showing a combination arrangement of hemispherical lenses in an integrator used in the device of the present invention. FIG. 6 is a reference example of an integrator. FIG. 3 is a diagram showing a combination arrangement of lenses in FIG. 1... Lamp, 2... Mirror, 3... Integrator, 4, 5... Hemispherical lens.

Claims (1)

[Scope of utility model registration request] In an apparatus in which light from a point light source is focused by a mirror onto an integrator composed of a plurality of lenses, and the incident light of each lens is projected onto a rectangular or square exposure surface in duplicate, the integrator has two lenses with different radii of curvature. Use a hemispherical lens of more than 100% of the size, and combine a lens with a radius of curvature of 1.2 times or more of the hemispherical lens in the other part in a part of the hemispherical lens located at the periphery, and increase the number of lenses in the lens. Irradiation equipment with an integrator that is less than 1/2 of the total number.