JPS6015053B2 - Copy machine lighting system - Google Patents

Description

[Detailed description of the invention] The present invention relates to a lighting device for a copying machine.

Generally, in a copying machine, the original to be copied is illuminated,
An image of this document is formed on a photosensitive recording medium by an imaging optical system, and the recording medium is exposed to light.

Exposure of the recording medium must be performed with a uniform illuminance distribution, but due to the cosine 4 rule in the imaging optical system, when the original is exposed uniformly, the illuminance distribution of the image on the recording medium will be It will no longer be uniform. Therefore,
The document must be illuminated with a certain illuminance distribution in consideration of the above-mentioned cosine fourth law and the like so that the recording medium is exposed with a uniform illumination distribution. on the other hand,
The illumination light source for illuminating the original is a tungsten type, in which a wire is stretched around the center of a transparent hollow cylinder, and tungsten light sources are distributed on the wire, and a crab light lamp is used. well known.

Among these light source tube lights, the tungsten type allows the illuminance distribution of illumination of the document to be relatively easily adjusted to the desired illuminance in the direction parallel to the longitudinal direction by adjusting the distribution of the light emitting source. It can be adjusted to the distribution.

However, in the case of crab light lamps, it is almost impossible to adjust the emission intensity distribution in the light source, and furthermore, since the light source is a surface light source, it is difficult to adjust the illuminance distribution without using an auxiliary light shielding plate. Even if a light shielding plate is used, sufficient adjustment is difficult. Furthermore, since the amount of light emitted by the crab light lamp is 4.0 times smaller than that of a tungsten type light source tube lamp, a plurality of crab light lamps must be used in order to obtain sufficient illuminance. In particular, when the illumination area is large, such as in the case of a full-surface exposure method, a large number of fluorescent lamps are required. In addition, in such cases, even if a tungsten type light source tube is used, it is difficult to match the illuminance distribution of the document illumination section to the desired illuminance distribution in the direction perpendicular to the longitudinal direction of the light source tube. be. An object of the present invention is to illuminate an illumination section with a sufficient amount of light with a smaller number of light source tube lights in a document illumination method using a large number of light source tube lights. An object of the present invention is to provide a lighting device for a copying machine, which allows relatively easy adjustment of the illuminance distribution in the copying machine.

Hereinafter, the present invention will be described by way of examples with reference to the drawings.

FIG. 1 schematically shows an example of a lighting device embodying the invention.

The main parts of the illumination device are composed of light source tube lights 1 and 2 and plane mirrors MI and M2. The light source tube lights 1 and 2 are crab light lamps, and are arranged with their longitudinal directions parallel to each other. A direction perpendicular to the drawing is a direction parallel to the longitudinal direction. Plane mirrors MI and M2 are provided corresponding to the light source tubes 1 and 2, respectively.

The plane mirror MI is provided parallel to the light source tube 1 along the light source tube 1 with its mirror surface facing the light source tube. The plane mirror M2 is provided parallel to the light source tube 2 with its mirror surface facing the light source tube 2. Reference numeral F indicates the surface of the document to be illuminated.

Now, suppose that point E (actually a straight line parallel to the direction perpendicular to the drawing) on the document surface F is the position that should be illuminated with the highest illuminance.The illumination device should be arranged as shown in Figure 1. Set up Then, point E is illuminated by direct light from light source tube lights 1 and 2 and reflected light from plane mirrors M1 and M2, but as is clear from the figure, for point E,
In addition to the light source tubes 1 and 2, images 1-i and 2-i of the light source tubes 1 and 2 formed by plane mirrors M1 and M2 are equivalent to actually existing as light source tubes.

Of course, the reflectance of the plane mirrors M1 and M2 is less than 100%, so if the above images 1-i and 2-i are considered as actual light source tube lights, the amount of light emitted by the light source tubes 1 and 2 is Although it is slightly smaller than the quantity. Therefore, point E is illuminated by four light source tube lights.

In the region to the right of point E, the contribution of the reflected light from the plane mirrors M1 and M2 to the illumination gradually decreases, and the illuminance is inversely proportional to the square of the distance from the light source. The further you go, the lower the illuminance becomes. In the region to the right of point P, the illuminance distribution is approximately the same as the illuminance distribution when only the light source tube lights 1 and 2 are present as light sources. On the other hand, in the area to the left of point E, the light reflected by the plane mirrors M1 and M2 and the light from the light source tube 2 are blocked by the plane mirror and light source tube located above them, so the illuminance gradually decreases. .

Therefore, the illuminance distribution on the document surface F is as shown by reference numeral 11. 0 The illuminance distribution 11 is almost uniform in the direction perpendicular to the drawing.

The illuminance distribution on the document surface by the illumination device, in the direction parallel to the drawing, depends on the arrangement position of the light source tube 1, the positional relationship of the light source tube 2 with respect to the light source tube 1, and the arrangement of the plane mirrors M1 and M2. In other words, by changing the arrangement position and inclination of the light source tube lights 1 and 2, or by changing the angle of intersection between the arrangement direction of the light source tube lights 1 and 2 (represented by reference numeral 1) and the document surface F, It can be changed.

In FIG. 2, an example of the illuminance distribution is indicated by reference numeral 12 when the intersection angle between the arrangement direction 1 of the light source tube lights 1 and 2 and the document surface F is changed in the illumination device shown in FIG. There is.

In the illuminance distribution 12, the illuminance near the point E is greater than that in the illuminance distribution 11. Of course, the illuminance distribution can also be changed by changing the number of light source tube lights and the number of plane mirrors.

In this manner, by using the illumination device according to the present invention, the document surface can be efficiently illuminated with a small number of light source tube lights.

Furthermore, it is possible to adjust the illuminance distribution on the document surface in a direction perpendicular to the longitudinal direction of the light source tube. FIG. 3 is an explanatory diagram for explaining one example of how to determine the disposition of the plane mirror MI.

Assuming that point E on the document surface F is the position to be illuminated with maximum illuminance, the light is reflected toward point E by the plane mirror MI. The light from the light source tube 1 must not be blocked by the light source tube 1, so one of the tangents drawn from point E to the light source tube! ．． The mirror surface must be placed below the intersection point m with the straight line connecting the central axes of the light source tubes 1 and 2 on the drawing, that is, the straight line 1 indicating the arrangement direction of the light source tubes 1 and 2.
In this example, the plane mirror MI is arranged so that its mirror surface coincides with the intersection m. Also, the direct light from the light source tube 2 that illuminates the point E is entirely included between the two tangents 12 and 13 drawn from the point E to the light source tube 2, and this direct light , since the point E must not be blocked by the plane mirror MI, the edge PM of the plane mirror MI is the tangent 1
Cannot exceed 2.

In this way, the arrangement position of the plane mirror MI is such that the light reflected by the plane mirror MI is not blocked by the light source tube 1 from the point E, and the illumination by the light source tube 2 is not obstructed from the point E. It is determined that two conditions must be met:

At this point, it will be obvious how to arrange the plane mirror M2. However, when determining the arrangement position of the light source tube and the reflector, the above method is not absolute, and the point is to determine the desired illuminance distribution on the document surface so that this illuminance distribution can be achieved. , it is sufficient to determine the above-mentioned arrangement position.

In the example shown in FIG. 4, the plane mirror MI is disposed below the intersection m.

In this case, the distance between the light source tube 2 and the light source tube 1 is larger than in the example shown in FIG. 3. FIG. 5 shows, according to the present invention,
An example of a full exposure type original illumination device to which an illumination device is applied is shown. This document illumination device is a combination of four sets of illumination devices according to the present invention, each consisting of two light source lamps and two plane mirrors.

That is, these four sets of lighting devices each include light source tube lights 21 and 22, plane mirrors M21 and M22, and light source tube light 2.
3, 24 and plane mirrors M23, M24, light source tube lamp 31,
32 and plane mirrors M31, M32, light source tube lights 33, 34
and plane mirrors M33 and M34. The area surrounded by the two-dot chain lines EI to E4 is the effective copying surface, and the document surface portion within this effective copying surface is effectively copied.

If we take into account the cosine fourth power law and open □ characteristic of the imaging optical system, the effective copying surface is generally such that the center part is low illuminance and the peripheral green part is high illuminance, for example, as shown in Fig. 6. It must be illuminated with an illuminance distribution as shown in . FIG. 7 shows an illumination device composed of light source tubes 21, 22 and plane mirrors M21, M22, and a pair of light source tubes 23, 2.
4 and plane mirrors M23 and M24, the illuminance distribution within the effective document surface is shown.

The curve 20 indicates the illuminance distribution, and it will be clear from the above description that such an illuminance distribution can be obtained with the arrangement of the lighting devices as shown in the figure. In the figure, the straight lines indicated by symbols L, L2 indicate the limits of specular reflection by the original teaching glass, and it is necessary to prevent the reflected light from the light source from entering the imaging optical system by the original guiding glass. , the illumination device must be placed outside this specular reflection limit surface. Light source tube lights 31, 32 and plane mirror M3
1. A lighting device composed of M32 and a light source tube light 33
, 34 and the illumination device constituted by the plane mirrors M33, M34, the light can be lowered at the center of the effective document surface.
An illuminance distribution is obtained that increases as it approaches the green ends E3 and B4, and by superimposing these illuminance distributions, an illuminance distribution as shown in FIG. 6 is realized.

On the other hand, in the apparatus shown in FIG.
, 23 and 24 are of tungsten type, and the distribution of the light source is adjusted so that the illuminance distribution in the longitudinal direction of the light source tube matches the desired distribution. , on the document surface illuminated by these light source tube lights, if the illuminance is set to be high at both ends in the longitudinal direction of the light source tubes and low at the center, these light source tube lights 21 and 22 and the plane mirrors M21 and M22 A lighting device, light source tube lights 23, 24, and a plane mirror M23,
Only by pairing with a lighting device constituted by M24,
An illuminance distribution as shown in FIG. 6 can be obtained.

In order to obtain the illuminance distribution as shown in Fig. 6 by using a crab light lamp as the light source tube lamp and using a pair of opposing illumination devices as in the case of using the above-mentioned tungsten type light source tube lamp, the area of the plane mirror must be Alternatively, a light shielding plate having a shape as shown in FIG. 9 may be used in a state as shown in FIG. 10 with respect to the light emitted from the light source tube.

In the figure, numerals 41 and 42 indicate light shielding plates. It goes without saying that the light shielding plates 41 and 42 are used by making the longitudinal direction parallel to the longitudinal direction of the light source tube and inserting the curved side green portion into the light beam that illuminates the effective document surface. do not have.
It goes without saying that a plane mirror as shown in FIG. 8 and a light shielding plate as shown in FIG. 9 may be used in common.

As described above, according to the present invention, a copying machine is capable of efficiently illuminating a document surface using a small number of light source tube lights, and is also capable of adjusting the illuminance distribution on the document surface even when using light source tube lights such as crab light lamps. can provide lighting equipment for

[Brief explanation of the drawing]

FIG. 1 is an explanatory side view showing one embodiment of the present invention, and FIG. 2 is an illustration of illuminance distribution adjustment according to the embodiment shown in FIG.
FIGS. 3 to 4 are diagrams for explaining an example, and FIGS.
FIG. 5 is a perspective view showing an example of a document illumination device to which the present invention is applied, FIG. 6 is a diagram showing an example of illuminance distribution to be realized on the effective document surface, and FIG. FIG. 8 is a diagram for explaining that the illuminance distribution shown in the figure is realized by the illumination device shown in FIG. 5, and FIG. FIG. 9 is a plan view showing an example of a light-shielding plate that can be used auxiliary to adjust illuminance distribution, and FIG. 10 is a plan view showing an example of a light-shielding plate as shown in FIG. It is an explanatory side view showing one example. 1, 2... Crab light lamp that is a light source tube light, M1, M2
...Flat mirror as a reflecting mirror, F... Original surface, 11, 12, 20... Illuminance distribution. I don't like the 4 figures, the 5 figures, the 6 figures, the 7 figures, the 6 figures, I don't like the figures in red. Figure 猪い 0 Figure

Claims (1)

[Scope of Claims] 1. n (≧2) light source lamps arranged so that their longitudinal directions are parallel to each other and their central axes are on the same plane, and m (1 ≦m≦n) Corresponding to each book, m plane mirrors are arranged so as not to interfere with the illumination function of other light source tube lights and reflect the light of the corresponding light source tube to the lighting section. The n light source tubes are arranged such that the arrangement direction of the light source tubes intersects with the document surface to be illuminated, and the longitudinal direction of the light source tubes is parallel to the document surface, and The mutual positional relationship of the light source tube lights, the arrangement position of the m plane mirrors, and the intersection angle between the above arrangement direction and the document surface,
An illumination device for a copying machine, characterized in that it is determined according to a desired illumination illuminance distribution on the document surface in a direction perpendicular to the longitudinal direction. 2. In claim 1, the n light source lamps are fluorescent lamps, and the areal shape of the reflective surfaces of the m plane mirrors is
1. A lighting device for a copying machine, characterized in that the lighting device is determined according to a desired illumination illuminance distribution in the longitudinal direction of a light source tube lamp on a document surface to be illuminated.