JPH06208174A - Document lighting system - Google Patents

Abstract

PURPOSE:To suppress the reduction of the document face illuminance to the minimum and reduce the illuminance irregularities in the longitudinal direction of a light source at a document illumination section by forming the second reflector into a reflecting face having a high mirror surface properly, and forming the first and third reflectors into reflecting faces having a high diffusion property. CONSTITUTION:The first reflector 2 is located below a light source 1, and it is formed with part of an ellipsoid located with the light source 1 and a document illumination section 6 at focal points respectively. The second reflector 3 is located above the light source 1, the reflected light axis 7 side is extended to the position where the light flux from the light source 1 is not directly radiated to the document illumination section 6, and second reflector 3 is formed with part of a paraboloid to guide the parallel light in the direction crossing the light axis 7. The third reflector 4 is formed into a plane shape to effectively receive the parallel light from the reflector 3 and reflect it toward the illumination section 6. The reflecting face of the reflector 3 is made the mirror surface, and reflecting faces of the reflectors 2, 4 are made coated surfaces. The light axis 7 sides of the reflectors 2, 4 are extended near the opening section of a slit 8, and the reduction of the illuminance the illumination section 6 can be suppressed to the minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an original illuminating device for irradiating a moving original with light using a rod-shaped light source having a plurality of light emitting portions in the longitudinal direction and a reflector in a copying machine, a facsimile or the like. Is.

[0002]

2. Description of the Related Art As shown in FIG. 1, a conventional document illuminating device of this type has reflectors a and b for effectively collecting a light beam from a rod-shaped light source c on a document irradiating section d. The reflection surface is made of a metallic material having a specular surface. The light source c at this time is rod-shaped and has a plurality of light emitting portions e in the longitudinal direction as shown in FIG.

When a halogen lamp is used for such a rod-shaped light source c, as shown in FIG. 3, illuminance unevenness occurs in the lamp irradiating direction in the document irradiation section d. This is because the luminous flux from the light emitting portion e of the light source c cannot be sufficiently diffused to the original irradiating portion d and a difference in luminous flux from the non-light emitting portion f occurs. In the case of a normal flat original with high diffusivity, the unevenness of irradiation is reduced due to the diffusion of the original, which causes almost no problem, but a flat original with high glossiness (high specularity) or a thick original as shown in FIG. There is a problem in reading the book document g.

That is, in the case of a flat original having a high glossiness, the influence of the uneven illumination is great, and the original density of the portion corresponding to the light emitting portion e of the light source c is read low. Appears. Further, in the case of a thick book manuscript g, when reading the vicinity of the binding part of a book, the manuscript information of the part corresponding to the light emitting part e of the light source c is omitted, and characters are missing or the density of the picture is lowered. The problem arises. This is because there is little diffusion by the document, and further, the mirror image h of the light source c approaches the reflected optical axis i, and this enters an imaging lens (not shown), and the document information is overlapped and read.

As measures against these problems, some means have been considered so far. An example of the prior art is given below. (1) An omnidirectional light diffusing means for the reflector is provided. For example, white diffusion coating is applied to the reflecting surface. (2) The reflecting plate is provided with a unidirectional diffusing means having a high diffusivity only in the longitudinal direction of the light source. For example, a hairline is inserted in the reflector in a direction perpendicular to the longitudinal direction of the light source.
Alternatively, the cross-sectional shape of the reflection plate in the longitudinal direction of the light source is made uneven (see, for example, Japanese Utility Model Laid-Open No. 53-136827). (3) A diffuser plate such as frosted glass is arranged between the light source and the optical path of the document irradiating section (see, for example, Japanese Utility Model Laid-Open No. 59-144649).

[0006]

Although any of the above-mentioned conventional techniques is a technique for improving the unevenness by blurring the mirror image, the above-mentioned conventional techniques (1), (2), (3) Therefore, there are problems as shown in (1) ′, (2) ′, and (3) ′ below. (1) 'Although there is an effect on uneven illuminance, if the entire surface of the reflecting mirror is a coated surface, the illuminance on the document surface is greatly reduced. (2) ′ The reduction of the illuminance on the document surface is small, but the effect on the uneven illuminance is insufficient. (3) 'The effect is insufficient. Further, in order to suppress a decrease in illuminance, there is a means of combining with a light condensing member such as a Fresnel lens, but the cost becomes high.

The present invention has been conceived in view of the above, and in an illuminating device that illuminates an original using a light source having a plurality of light emitting portions in the longitudinal direction and a reflector, a reduction in the illuminance of the original is suppressed to a minimum. Another object of the present invention is to provide a document illuminating device in which the illuminance unevenness in the longitudinal direction of the light source is small in the document illuminating section.

[0008]

In order to achieve the above object, a document illuminating device according to the present invention is provided with a first reflecting plate located below a rod-shaped light source 1 having a plurality of light emitting portions in the longitudinal direction. And a second reflector located above the light source 1, and a third reflector provided at a position facing the first and second reflectors with a reflection optical axis 7 therebetween. In other words, the second reflection plate has a high specular reflection surface, and the first and third reflection plates have a high diffusion property. The reflecting surface of the second reflecting plate is a unidirectional diffusive surface having high diffusivity only in the longitudinal direction of the light source 1. Further, the diffusive reflecting surface of each reflecting plate is arranged at a position corresponding to the light emitting portion of the light source 1. Further, the first reflector and the second reflector are integrated. The above-mentioned highly diffusive reflecting surface is used as it is as the base material of the reflecting plate member, and the coated surface, the sheet surface, and a combination thereof.

[0009]

[Operation] The light beam from the light source 1 is reflected by each reflection plate and is applied to the document irradiation section 6. At this time, the light source 1
The light flux from is diffused by the diffusing surface of each reflecting plate, so that there is no variation in illuminance among the light emitting portions of the rod-shaped light source 1 having a plurality of light emitting portions.

[0010]

EXAMPLE An example of the present invention will be described with reference to FIG. FIGS. 5A and 5B show the first embodiment, in which 1 is a light source, and 2, 3, 4 are located around the light source 1, and the light of the light source 1 is placed on the platen glass 5. Original illumination unit 6
It is the 1st, 2nd, and 3rd reflectors for irradiating toward.

The first reflecting plate 2 is located below the light source 1 and is composed of a part of an elliptical surface having the light source 1 and the document irradiating section 6 as focal points. In addition, the second reflector 3
The reflection light axis 7 side from the document irradiation section 6 is extended to a position which is located above the light source 1 and the light beam from the light source 1 does not directly irradiate the document irradiation section 6, and a parallel light beam in a direction crossing the reflection light axis 7. Is formed by a part of a parabolic surface having the light source 1 as a focus. Further, the third reflecting plate 4 effectively receives the parallel light beam from the second reflecting plate 3 to receive the original irradiating section 6
It is configured to be flat so as to reflect toward. The reflected optical axis 7 is guided through the slit 8 toward the condenser lens (not shown) side of the optical system.

The reflecting surface of the second reflecting plate 3 is a mirror surface, and the reflecting surfaces of the first and third reflecting plates 2 and 4 are painted surfaces. And the first and third reflectors 2 and 4
By extending the reflection optical axis 7 side to the vicinity of the opening of the slit 8, the reduction of the illuminance of the document illumination unit 6 is suppressed to the minimum.

FIGS. 10A and 10B are views for explaining the case where the reflection optical axis 7 side of the first and second reflection plates 2 and 4 is extended to the vicinity of the opening of the slit 8. As shown in 10 (a), when the reflection plates a and b are brought closer to the reflection optical axis 7 side so that the opening 9 formed by the reflection plates a and b is narrowed, the mirror image 1 of the light source 1 is formed due to the structure of the reflection plate a. Since ′ also approaches the reflected light axis 7 and is easily affected by the uneven illumination, normally, as shown in FIG. 10B, the reflector a on the light source 1 side should be extended close to the reflected light axis 7. Without, the reflector opening 9
Is designed to be larger than the opening width of the slit 8 and the mirror image 1 ′ is separated from the reflected optical axis 7 to some extent to reduce the influence of uneven illuminance. Moreover, on the other hand, the light flux of the light source 1 cannot be effectively used because the reflector opening 9 is enlarged.

In the embodiment of the present invention shown in FIGS. 5A and 5B, the reflecting surfaces of the first and third reflecting plates 2 and 4 located on both sides of the reflecting optical axis 7 are coated surfaces. Since the mirror image 1 ′ of the light source 1 is blurred so that the reflected light is diffused, the first and third reflecting plates 2 and 4 can be respectively extended to near the reflected light axis 7, and the light flux from the light source 1 is effective. It was possible to suppress the decrease of the illuminance of the original. Further, since the original illumination unit 6 is irradiated with diffused light, the condensing distribution A is wider than the condensing distribution B of the illuminating device constituted only by the specular reflection surface, as shown in FIG. Become. As a result, it is possible to avoid the influence that the illuminance of the document illumination unit 6 varies due to the deviation of the light condensing position due to the manufacturing variation of the reflecting plate. Further, the irradiation of the diffused light has an advantage that it is possible to reduce the phenomenon that the illuminance is lowered and the copy is fogged when the original is floating from the original table.

FIGS. 6 (a) and 6 (b) show a second embodiment of the present invention. In the figures, 10, 11 and 12 have the same structure as the first embodiment and are located around the light source 1. The first, second, and third reflectors, and the reflecting surfaces of the first and third reflectors 10 and 12 are coated surfaces as in the first embodiment, but the second reflecting plate is used. The reflection surface of the plate 11 is a unidirectional diffusion surface having high diffusivity only in the longitudinal direction of the light source 1. Further, the second reflecting plate 11 is formed in a planar shape in which the light flux from the light source 1 is guided to the first reflecting plate 10. Since the first reflector 10 is closer to the light source 1 than the third reflector 12,
It is preferable to increase the diffusivity.

Here, the light flux diffused in the longitudinal direction of the light source 1 by the second reflection plate 11 is guided to the first reflection plate 10 and further diffused by the first reflection plate 10 to enhance the diffusivity. . At this time, since the second reflection plate 11 has unidirectional diffusion, it is possible to suppress a decrease in illuminance.

FIGS. 7 (a) and 7 (b) show a third embodiment of the present invention. The difference between this embodiment and the first and second embodiments is that the first and third reflecting plates 13 are different from each other. , 14 is not applied to the entire surface, but is applied to the position corresponding to the light emitting portion of the light source 1. Irradiation unevenness is effective if the light flux from the light emitting portion of the light source 1 is diffused.
Properly select whether the coating width of the above is the entire width of the reflection plates 13 and 14 as shown in FIG. 7A or only the portion near the reflection optical axis 7 side as shown in FIG. 7B. As a result, it is possible to obtain a lighting device with even less unevenness in illuminance.

FIG. 8 shows a fourth embodiment of the present invention. The difference between this embodiment and the first, second and third embodiments is that the first reflection plate and the second reflection plate are different from each other. The point is that the plate and the plate are constituted by a set of reflecting members 16. This facilitates processing and allows the use of the light flux from behind the light source 1,
The surface illuminance can be increased accordingly.

9 (a), 9 (b) and 9 (c) show a fifth embodiment of the present invention. The first reflector 17 is the first reflector 13 of the third embodiment. Similarly to the above, the coating part 15 is partially applied. On the other hand, the third reflector 18 is separated from the light source 1 and has a diffusivity of the first reflector 1.
Since it may be lower than 7, the unidirectional diffusive surface portion 19 is partially provided instead of the painted surface. FIG. 9A shows an example in which each coating surface portion 15 and the one-way diffusive surface portion 19 are provided in a strip shape on the side of the reflection optical axis 7, and FIGS. 9B and 9C show the both surface portions 15 and 19 as the light source. An example is shown in which the full width (b) and the partial width (c) are set at the position corresponding to the light emitting portion 1 and in the direction perpendicular to the longitudinal direction of the light source 1.

In the fifth embodiment, it is possible to increase the luminous flux from the third reflecting plate 18 side, which has a smaller light source viewing angle than the first reflecting plate 17 side, and further suppress the reduction of the document surface illuminance. . The same effect can be achieved by applying a coating having a lower diffusivity to the third reflector 4 in the first embodiment than the first reflector 2. In this example, the combination of the unidirectional diffusive surface portion and the painted surface portion is used.
-The second reflecting plates 17 and 18 may be combined with the reflecting surface portion as it is and the sheet member.

[0021]

According to the present invention, in an illuminating device which illuminates an original using a light source having a plurality of light emitting portions in the longitudinal direction and a reflector, the reduction of the illuminance of the original is minimized and the original illuminating section is used. In, it is possible to reduce the illuminance unevenness in the longitudinal direction of the light source.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conventional example.

FIG. 2 is a front view showing a rod-shaped light source.

FIG. 3 is a diagram showing the amount of light in the longitudinal direction of a rod-shaped light source.

FIG. 4 is a cross-sectional view showing a state in which a binding portion of a book is copied by a conventional device.

FIG. 5A is a sectional view showing a first embodiment of the present invention. (B) is the inclination figure.

FIG. 6A is a sectional view showing a second embodiment of the present invention. (B) is the perspective view.

7A and 7B show a third embodiment of the present invention,
FIG. 3 is a perspective view showing different configurations.

FIG. 8 is a sectional view showing a fourth embodiment of the present invention.

9A, 9B, and 9C are perspective views showing a fifth embodiment of the present invention and showing different configurations.

10A and 10B are explanatory views showing the relationship of the opening of the reflector opening with respect to the reflection optical axis.

FIG. 11 is a diagram showing a comparison of light distributions on a document surface.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 1 '... Mirror image, 2, 10, 13, 17 ... 1st reflecting plate, 3, 11 ... 2nd reflecting plate, 4, 12, 14, 1
8 ... Third reflector, 5 ... Platen glass, 6 ... Original illumination unit, 7 ... Reflected optical axis, 8 ... Slit, 9 ... Reflector aperture.

Claims (8)

[Claims] 1. A first reflecting plate located below the rod-shaped light source 1 having a plurality of light emitting portions in the longitudinal direction, a second reflecting plate located above the light source 1, and the first and second reflecting plates. The second reflecting plate is a reflecting surface having high specularity, and the third reflecting plate is provided at a position facing the two reflecting plates with the reflection optical axis 7 therebetween. An original illuminating device, characterized in that the reflecting plate is a highly diffusive reflecting surface. 2. The original illuminating device according to claim 1, wherein the reflecting surface of the second reflecting plate is a unidirectional diffusive surface having high diffusivity only in the longitudinal direction of the light source 1. 3. The document illuminating apparatus according to claim 1, wherein the diffusive reflecting surface of each reflecting plate is arranged at a position corresponding to the light emitting portion of the light source 1. 4. The document illuminating device according to claim 1, wherein the first reflector and the second reflector are integrally formed. 5. The reflective surface having a high diffusivity is in a state where the base material of the reflective plate member remains as it is.
The document illuminating device described in 3 or 4. 6. The document illuminating device according to claim 1, wherein the reflective surface having high diffusivity is a coated surface. 7. The original illuminating device according to claim 1, wherein the reflective surface having high diffusivity is a sheet surface. 8. The reflective surface having high diffusivity is a combination of a unidirectional diffusing surface having high diffusivity only in the longitudinal direction of the light source 1, a base surface, a painted surface, a reflective surface having different diffusive properties such as a sheet surface. The document illuminating device according to claim 1, 2, 3, or 4.