JPH059719Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention illuminates a document such as a book or office document placed on a platen, and forms an image of the reflected light on an image sensor or photoreceptor. It relates to an original illumination device that reads the image or forms the latent image on a photoreceptor, and particularly relates to an improvement of the original illumination device that eliminates variations in the amount of light to the original irradiation section and eliminates reading errors. It is something.

[Prior Art] As an example of a conventional document illumination device, one incorporated in an image reading device will be described.
As shown in Figures to Figure 7, a pair of illumination lamps b, b are disposed below the transparent platen a, which is fixedly arranged, and the lamps b, b are moved along the lower surface of the platen a. Original c placed on a
A device in which a slit-shaped partial image of the original document c is sequentially formed on image sensors f and f through an imaging lens d, and the images are read. Are known.
In addition, g in FIG. 6 indicates the pair of illumination lamps b, b.
A ball screw moves the device housing h to which the document is attached in the direction of the arrow, and j indicates a mirror that causes the reflected light from the document c to enter the imaging lens d.

[Problems to be solved by the invention] By the way, in the conventional device, the illumination lamps b and b are composed of fluorescent lamps, etc., and the outer circumferential surface of the tube has a mirror-like structure. The light emitted from these illumination lamps b, b is
Multiple reflections occurred between the surface of the document c and the outer peripheral surfaces of the illumination lamps b, and this light sometimes illuminated the document irradiation section α multiple times. Since the reflected light from the document c increases in proportion to the amount of white information of the document c, the amount of irradiation to the document irradiation section α varies depending on the type of document, and the illumination conditions fluctuate, causing There was a problem in that it caused an error in reading the density, resulting in a decrease in reading accuracy.
In particular, with color reading devices that use the so-called light source switching method, which flashes multiple light sources of different colors and reads the reflected light, if the lighting conditions change, it may not only be possible to incorrectly read the original density, but also cause the color composition itself to be read incorrectly. There were problems in that it could be made incorrectly and would no longer function properly.

This also applies to a document illumination device that forms an electrostatic latent image on a photoreceptor; the exposure conditions vary depending on the amount of white information on the document, and the potential of the latent image formed on the photoreceptor changes. There was a problem that the copy balance became unstable due to variations in the copy balance.

[Means for Solving the Problems] The present invention has been made in view of the above problems, and its object is to provide an original illumination device that hardly causes changes in the amount of light to the original illumination section. It is in.

That is, the present invention provides a document illumination device in which a tubular light source for document illumination is disposed below a transparent platen, and the document surface on the platen is sequentially illuminated in a slit shape by relatively moving the platen or the light source. In the above, the light source is provided with a reflection regulating portion that suppresses reflected light that is scattered on the surface of the document illuminated by the light source, reflected on the surface of the light source, and directed toward the slit-shaped document illumination portion again. It is characterized by:

In such a technical means, the reflection regulating section absorbs the reflected light from the original, or deflects the reflected light to a part other than the slit-shaped original irradiation part, and prevents the reflected light from heading toward the original irradiation part. The structure can be arbitrary as long as it suppresses the light, for example, leaving an opening for light irradiation and providing a light absorbing part on the outer surface of the tube light source, or roughening the outer surface of the tube and adding a light diffusing part. It is also possible to configure this by providing a configuration in which the reflected light is diffusely reflected.

Furthermore, in this technical means, the light source is fixedly arranged and the platen side is moved to sequentially illuminate the document surface in a slit shape, or the platen is fixedly arranged and the light source side is moved to illuminate the document surface. The configuration may be arbitrary.

Further, this device can be applied to a document reading device or an exposure device such as a copying machine.

[Function] According to the above-mentioned technical means, since the tubular light source is provided with a reflection regulating section, multiple reflected light traveling from the outer surface of the light source toward the slit-shaped document irradiation section is suppressed and reduced. be able to.

[Example] Hereinafter, an example in which the present invention is applied to an image reading device will be described in detail with reference to the drawings.

◎ First Embodiment As shown in FIG. 1, this device includes a platen glass 1, a housing 2 disposed on the lower surface of the glass so as to be movable in the direction of the arrow, and a pair of fluorescent lamps each attached to the housing 2. It is composed of lamps 3, 3, a mirror 4, a pair of imaging lenses 5, 5, and a pair of image sensors 6, 6.

As shown in FIG. 2, the fluorescent lamps 3, 3 have a reflective film 9 and a fluorescent film 10 sequentially coated on the inner wall of the tube 8 along its length, leaving an opening 7 for light irradiation. A black heat-resistant rubber material 11 having a substantially C-shaped cross section is fitted along the length of the outer wall of the tube 8, leaving the opening 7, using its elasticity. .

In this apparatus configured in this manner, when the original 12 on the platen glass 1 is illuminated by the pair of fluorescent lamps 3, 3, the original 12 is illuminated.
The reflected light p from the two surfaces is absorbed by the black heat-resistant rubber material 11 as shown in FIG. As a result, the illumination conditions for the document irradiation section α can be kept constant.

Therefore, in this device, the document 12 on the platen glass 1 can be illuminated under the same conditions regardless of the amount of white information on the document 12, which eliminates reading errors in document density and improves reading accuracy. have.

In this embodiment, a heat-resistant rubber material 11 having a substantially C-shaped cross section is fitted around the outer periphery of the fluorescent lamps 3, 3 to form a light absorbing section. A light absorbing material may be applied directly to the outer peripheral surfaces of the lamps 3, 3, and the light absorbing portion may also be formed using this absorbing material.

◎ Second Embodiment The apparatus of this embodiment is constructed by replacing the fluorescent lamps 3, 3 of the apparatus according to the first embodiment with fluorescent lamps 3d, 3d as shown in FIGS. 4 and 5. be. That is, in this device, the fluorescent lamps 3d, 3d have a fluorescent film 10 coated on the inner wall of the tube 8 along the length direction, and the outer peripheral surface thereof is roughened to form a diffusion portion 14. ing.

Therefore, in this device, the fluorescent lamp 3
When the document 12 on the platen glass 1 is illuminated by irradiating light d and 3d, the reflected light p reflected from the surface of the document 12 and directed toward each of the fluorescent lamps 3d and 3d is reflected by the diffusion portions 14 and 14 of the fluorescent lamps 3d and 3d. Therefore, the reflected light p heading toward the document irradiation section α
is significantly reduced. Therefore, the document irradiation section α
The influence of multiple reflected light is weakened and uniform irradiation is achieved.

[Effect of the invention] As described above, in the document illumination device of the present invention, since the reflection regulating section is provided in the tubular light source, it is possible to suppress and reduce multiple reflected light directed toward the slit-shaped document irradiation section. can.

Therefore, irrespective of the amount of white information of the original placed on the platen, the amount of irradiation to the original irradiation section becomes uniform, which has the effect of stabilizing the illumination conditions.

[Brief explanation of the drawing]

1 to 3 show a first embodiment in which the present invention is applied to an image reading device, FIG. 1 is a perspective view of the image reading device, FIG. 2 is a sectional view of the fluorescent lamp, and FIG. Figure 3 is a partially enlarged sectional view of this device.
4 and 5 show the second embodiment, FIG. 4 is a sectional view of the fluorescent lamp of this device, FIG. 5 is a partially enlarged sectional view of the fluorescent lamp, and FIGS. The figures show a conventional image reading device, with FIG. 6 being a perspective view thereof, FIG. 7 being a sectional view thereof, and FIG. 8 being a partially enlarged sectional view thereof. Description of symbols, 1...Platen glass, 3...Fluorescent lamp, 6...Image sensor, 8...Tube, 11
...Heat-resistant rubber material, 12... Original, 14... Diffusion part, α... Original irradiation part.

Claims (1)

[Claims for Utility Model Registration] (1) A tubular light source for document illumination is provided below a transparent platen, and the document surface on the platen is sequentially illuminated in a slit shape by relatively moving the platen or the light source. In the document illuminating device, the light source is configured to suppress reflected light that is scattered on the surface of the document illuminated by the light source, reflected on the surface of the light source, and directed toward the slit-shaped document irradiation section again. A document illuminating device characterized by being provided with a reflection regulating section. (2) The document illumination device according to claim 1, wherein the reflection regulating section is a light absorbing section formed on the outer surface of the light source. (3) The document illumination device according to claim 1, wherein the reflection regulating portion is a diffusing portion formed by roughening the outer surface of the light source.