JPH02135607A - Illuminating device - Google Patents

Abstract

PURPOSE:To prevent unevenness in illuminance on a copy even when using such a light source that the amount of a light emitted by it is not uniform, by providing a reflecting plate portion with a light absorbing portion for absorbing reflected light, the reflecting plate portion corresponding to a light emitting portion. CONSTITUTION:A scanning head 1 is disposed below a transparent glass 21 on which a copy 19 is placed, and a line sensor 15 scans (main scanning) the copy 19 in one direction through the opening 23 of a reflecting plate 5 via an optical system 13 while the copy 19 is illuminated by an illuminating device 7, and in addition, the scanning head 1 is forced to move perpendicular to the main scanning so that the copy 9 is scanned perpendicular to the main scanning. On that portion of the reflecting plate 5 which corresponds to the light emitting portion 53 of a halogen lamp 51 (light source 3) are light absorbing portion 25 for absorbing reflected light is formed. The light absorbing portion 25 comprises a black tape 27 of predetermined size caused to adhere thereto. The center of the tape 27 is aligned with that of the emitting portion 53 and preferably the width of the tape 27 is made larger than the length of the emitting portion 53, and hence light reflected by the light emitting portion 53 is absorbed by the tape 27 to make the amount of light from the lamp 51 uniform in the longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an illumination device used in facsimile image reading devices, copying machines, and the like.

(Prior art) In facsimile image reading devices, copying machines, etc., an illumination device illuminates the document surface, an optical system forms an image of the document surface on a line sensor or a photoreceptor, and the image is read or a latent image is formed. I'm trying to get it.

Most of these lighting devices consist of a light source of a predetermined length and a reflector, and the light is emitted directly from the light source to the document, and the reflected light is emitted from the light source via the reflector. The document surface is illuminated with light.

In order to improve lighting efficiency, it is desirable to use a halogen lamp or the like with high luminous intensity as the light source of the lighting device.

On the other hand, in a halogen lamp, as shown by reference numeral 51 in FIG. 9, a filament forming a light emitting part 53 is connected linearly through a conductor part 55 inside a glass case, and the conductor part 55 is connected to a holder 57 made of a wire. The light intensity distribution is as shown in FIG.

That is, the amount of light at a location corresponding to the light emitting section 53 is large as shown in (a) in FIG. 10, and the amount of light at a location corresponding to the conductor section 55 is small as shown in (b) in FIG.

(Problem to be Solved by the Invention) Therefore, when trying to use a halogen lamp 51 or the like with high luminous intensity, the light source itself is inherently uneven in the amount of light in its longitudinal direction, resulting in uneven illuminance on the document surface. (In order to do this, the light source had to be moved away from the document surface, which caused the problem that it was not possible to downsize the entire device such as a facsimile or copying machine.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to prevent uneven illuminance from occurring on the document surface even when using a light source such as a halogen lamp that has an uneven light amount. It is an object of the present invention to provide an illumination device in which a light source can be placed close to the surface of a document, and which can reduce the size of the entire apparatus such as a facsimile machine or a copying machine.

(Means for Solving the Problems) In order to achieve the above object, a first invention provides a light source in which a plurality of light emitting parts for illuminating a document surface are arranged in a straight line at intervals; an illumination device comprising: a reflector that reflects illumination light and irradiates it onto a document surface; and a light absorbing portion that absorbs the reflected light is provided in a portion of the reflector that corresponds to the light emitting portion. Features.

A second invention also provides: a light source in which a plurality of light emitting parts are arranged in a straight line at intervals for irradiating a document surface; a reflecting plate that reflects illumination from the light source and irradiates the document surface; The lighting device is characterized in that a light diffusing section for diffusing reflected light is provided in a portion of the reflecting plate corresponding to the light emitting section.

(Function) Even if a light source whose light intensity is non-uniform in the longitudinal direction is used, according to the first invention, the light reflected from the light emitting portion is absorbed by the light absorbing portion, thereby making the light intensity uniform in the longitudinal direction of the light source.

Further, according to the second aspect of the invention, the light reflected from the light emitting part is diffused by the light diffusing part, thereby making the amount of light uniform in the longitudinal direction of the light source.

Therefore, according to the first and second inventions, even if a halogen lamp or the like is used as a light source, the light source can be placed close to the document surface without causing uneven illuminance on the document surface. The overall size of the device can be reduced.

In this case, the light absorbing portion can be simply constructed using a black tape or a large portion.

Further, the light diffusing portion can be simply configured with a convex surface or the like.

(Example) Hereinafter, a case where an example of the present invention is applied to an illumination device provided in a scanning head of an image reading device will be described.

FIG. 1 shows a schematic cross-sectional view of a scanning head.

3 is a scanning head, and the scanning head 1 includes an illumination device 7 consisting of a light source 3, a reflecting plate 5, etc., and a plurality of reflecting mirrors 9A, 9B, 9C.
, 9D, 9E, 9F, an optical system 13 consisting of an imaging lens 11, etc., and a line sensor 15 consisting of a CCD etc.,
In the figure, 17 indicates the housing of the scanning head 1.

The scanning head 1 has a transparent glass 21 on which an original 19 is placed.
The line sensor 15 reads one direction of the document 19 irradiated by the illumination device 7 (main scanning) through the optical system 13 through the aperture 23 of the reflecting plate 5, and also in the direction orthogonal to the main scanning. The scanning head l is moved to read in a direction perpendicular to the main scanning (sub-scanning).

The reflector plate 5 is attached to the housing 17 together with a halogen lamp 51 as the light source 3 via a holder (not shown).

Figure 2 is a plan view of the main parts of the reflector, Figure 3 is m-m of Figure 2.
A line cross-sectional view is shown.

The reflective plate 5 has a curved cross section, and the original 19 is placed on the reflective plate 5.
A horizontally long aperture 23 is formed to guide reflected light from the surface to the optical system 13.

Further, the light emitting portion 5 of the halogen lamp 51 on the reflection plate 5
A light absorbing portion 25 that absorbs reflected light is formed in a portion corresponding to No. 3.

In the embodiment, as shown by diagonal lines in FIG. 2, the light absorbing portion 25 is constructed by adhering a black tape 27 of a predetermined width and length. Furthermore, the tape 27 is not adhered to the entire area of the reflector 5 corresponding to the light emitting section 53, leaving a portion where the tape 27 is not adhered to adjust the amount of reflected light absorbed.

In this case, the center of the width of the tape 27 is desirably aligned with the center of the length of the light emitting section 53, and the width of the tape 27 is desirably larger than the length of the light emitting section 53.

According to such a configuration, the light reflected from the light emitting section 53 is absorbed by the tape 27, so that the amount of light reflected from the light emitting section 53 (A) is reduced, as shown in FIG. The amount of light in the light emitting portion 53 including the reflected light can be made equal to the amount of light in the conductor portion 55 (b), and the amount of light can be made uniform in the longitudinal direction of the halogen lamp 51.

Therefore, the halogen lamp 51 can be disposed close to the original 19 without causing uneven illuminance on the original surface, and the image reading apparatus can be made smaller.

In this case, the same effect can be obtained by configuring the light absorbing section 25 with a large portion of the reflecting plate 5 cut out instead of the tape 27.

Next, a second example will be described.

FIG. 4 is a plan view of the main part of the reflector according to the second embodiment, and FIG.
The figure and FIG. 6 are the V-V line in FIG. 4, Vl-■I! ,! A cross-sectional view is shown.

In the second embodiment, a light diffusing section 31 for diffusing reflected light is formed in a portion of the reflecting plate 5 corresponding to the light emitting section 53 of the halogen lamp 51.

In the embodiment, the light diffusing portion 31 is constituted by a convex surface 33 extending in the width direction of the reflecting plate 5 with a predetermined width.

According to this second embodiment, since the reflected light from the light emitting section 53 is diffused by the convex surface 33, as shown in FIG.
The light intensity of the light emitting part 53 and the conductor part 55 are reduced by reducing the light intensity of the reflected light in the third part (a) and increasing the light intensity of the reflected light in the conductor part 55 part (b). The amount of light can be made equal.

Therefore, the amount of light can be made uniform in the longitudinal direction of the halogen lamp 51, and the size of the image reading device can be reduced as in the previous embodiment.

In the embodiment, an illumination device that illuminates the document surface with both direct light and reflected light has been described, but the present invention is of course applicable to an illumination device that illuminates the document surface only with reflected light. In this case, it is necessary to increase the output of the light source because the surface of the document is irradiated with only reflected light, but since there is no direct light influence, the amount of light can be more evenly distributed in the longitudinal direction of the light source.

(Effects of the Invention) As is clear from the above description, according to the present invention, even if a light source such as a halogen lamp with an uneven light amount is used, the illumination on the document surface will not be uneven (the light source can be The device can be placed close to the surface, and the entire device such as a facsimile or a copying machine can be made smaller.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of the scanning head, Fig. 2 is a plan view of the main part of the reflection plate, Fig. 3 is a sectional view taken along the ITI-III line in Fig. 2, and Fig. 4 is a reflection diagram according to the second embodiment. Plan views of the main parts of the plate, FIGS. 5 and 6, are taken along line V-V in FIG. 4. 7 and 8 are right diagrams of light intensity, FIG. 9 is a front view of the halogen lamp, and FIG. 1O is a diagram of the light intensity distribution of the halogen lamp. In the figure, 3 is a light source, 5 is a reflector, 7 is an illumination device, 19 is an original, 25 is a light absorption section, 31 is a light diffusion section, 51 is a halogen lamp, and 53 is a light emission section. Patent Applicant: Asahi Optical Industry Co., Ltd. Agent, Patent Attorney: Kunio Miura

Claims (5)

[Claims] (1) An illumination device comprising: a light source in which a plurality of light emitting units are arranged linearly at intervals to illuminate the document surface; and a reflector that reflects the illumination from the light source and irradiates the document surface. A lighting device characterized in that a light absorbing portion that absorbs reflected light is provided in a portion of the reflecting plate corresponding to the light emitting portion. (2) The illumination device according to claim 1, wherein the light absorbing section is composed of a light absorbing material attached to a reflecting plate. (3) The lighting device according to claim 1, wherein the light absorbing portion is formed by a cutout portion obtained by cutting out a reflection plate. (4) An illumination device comprising: a light source in which a plurality of light emitting units are arranged linearly at intervals to illuminate the document surface; and a reflector that reflects the illumination from the light source and irradiates the document surface. An illumination device, characterized in that a light diffusing portion for diffusing reflected light is provided in a portion of the reflecting plate corresponding to the light emitting portion. (5) The illumination device according to claim 4, wherein the light diffusion section is constituted by a convex surface formed on a reflection plate.