JPS60182857A - Original reader - Google Patents

Abstract

PURPOSE:To eliminate uneven resolution by providing a white reflection board to a position opposed to both ends of a fluorescent light source and a position at the outside of an original so as to increase the luminous amount at the both ends of the fluorescent light source. CONSTITUTION:The reflected light from an original 1 irradiated by the fluorescent light source 3 is reflected on a reflecting mirror 4 through a slit 9a at the lower side of a lamp housing 9 and incident to a read element 6 via an image forming lens 5. The white reflecting plate 8 is provided at the outside of the original at the both ends of the luminous light source 3, the light from the both ends of the fluorescent light source wasted in a conventional reader is reflected on the reflecting plate 8 and irradiated on the circumferential part of the original 1. As a result, the decrease in the surrounding luminous amount is compensated in the illuminance distribution of the original plane and the original plane is irradiated almost uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a document reading device in an image input device such as a facsimile machine.

Structure of the conventional example and its problems In a conventional document reading device with a stationary document and a moving optical system, a document 1 is placed on a document table glass 2, as shown in FIG. Scanning is performed by moving an optical system 7, which includes a light source 3, a reflecting mirror 4, an imaging lens 6, a reading element 6 which is a plane scanning type image sensor, etc., as shown by a chain line. This scanning is called a sub-scan, and the reading of the document 1 by the reading element 6 in a direction perpendicular to this is called a main scan.

In such conventional devices, a fluorescent lamp is often used as the light source 3 because it is inexpensive. Due to the characteristics of fluorescent lamps, the light intensity decreases greatly at both ends, and therefore there is a shortage of light meters at both ends, so the length of the fluorescent lamp should be adjusted to avoid using this part as much as possible. It is set longer than the original width.

However, even with this arrangement, the illuminance distribution on the document surface that is actually illuminated is shown in FIG. Also,
Since the life span of a fluorescent lamp due to aging is determined based on the light intensity level at both ends where the light intensity is lowest, there is also the disadvantage that the replacement life of the fluorescent lamp is relatively short.

OBJECTS OF THE INVENTION An object of the present invention is to provide an improved document reading device that can increase the total amount of light at both ends of a fluorescent light source, eliminate uneven resolution, and extend the replacement life of the fluorescent light source. It is in.

Structure of the Invention The document reading device according to the present invention effectively utilizes the amount of light at both ends of the fluorescent light source, which was wasted in the past.
A white reflecting plate is provided at a position facing both ends of the fluorescent light source and disposed between the document mounting table glass outside the document area and the fluorescent light source.

DESCRIPTION OF EMBODIMENTS FIGS. 3 and 4 show an embodiment of the present invention, in which members having similar functions to those in the conventional device shown in FIG. 1 are given the same reference numerals. be. White reflector 8
is provided on the upper surface of a lamp housing 9 that surrounds the fluorescent light source 3, and is located between the document table glass 2 and the fluorescent light source 3. This white reflector 8 is provided over the entire upper surface of the lamp housing 9 in the original sub-scanning direction A shown in FIG. 3, and is provided over the entire upper surface of the lamp housing 9 in the original main scanning direction B shown in FIG. They are provided at positions facing both ends of the fluorescent light source 3 extending outside the placement area. The white reflector 8 only needs to have a white reflective surface at least on the fluorescent light source 3 side;
It is preferable to arrange them as close together as possible.

The reflected light from the document 1 irradiated by the fluorescent light source 3 is
After passing through the slit 9a at the bottom of the lamp housing 9 and being reflected by the reflecting mirror 4, the light is focused by the imaging lens 5 and enters the reading element 6.

Since the reading element 6 is a self-scanning image sensor, main scanning is performed by sequentially reading pixels for one line. 1
When the line has been read, the optical system 7 moves to perform sub-scanning, and the reading element 6 reads the next line in the same manner.

In the document reading device according to the present invention, since the white reflective plates 8 are provided at both ends of the fluorescent light source 3, the light from both ends of the fluorescent light source, which was previously wasted, is reflected by the outer tube wall. The light, which is transmitted through the outer tube wall and multiple-reflected by the inner tube wall, is reflected by the white reflecting plate 8 and illuminates the peripheral area of the original 1. The increase in the amount of light at the periphery of the document due to the white reflection plate 8 is about 7 to 10%, which is almost the same as the amount of light at the center of the document. Therefore, the decrease in peripheral light intensity in the illuminance distribution on the document surface as shown in FIG. 2 is compensated for, and the document surface is illuminated almost uniformly.

In the case of a document reading device in which the distance between the document platen glass 2 and the fluorescent light source 3 is relatively small, the white reflective plate 8 is placed at the bottom of the document platen glass 2, as shown in FIGS. It may be provided at a position facing both ends of the fluorescent light source 3 outside the original document area.

Effects of the Invention As shown in L, according to the document reading device of the present invention, a white reflective plate is provided between the document platen glass and the fluorescent light source, at a position outside the document area and facing both ends of the fluorescent light source. Since this is provided, it is possible to compensate for a decrease in peripheral light intensity in the illuminance distribution on the document surface, and to illuminate the document surface almost uniformly. Therefore, unevenness in resolution due to differences in light intensity is eliminated, and the replacement life of the fluorescent light source can be significantly extended.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional document reading device, FIG. 2 is a diagram showing an actual illuminance distribution on a document surface illuminated by a fluorescent lamp, and FIG. 3 is a document reading device according to an embodiment of the present invention. 4 is a schematic front view of the same device, FIG. 5 is a schematic front view showing another embodiment, and FIG. 6 is a schematic side view of the same device. 1...Original, 2...Original table glass, 3...
Fluorescent light, 4...Reflecting mirror, 5...Imaging lens, 6...Reading element, 7...Optical system, 8...
White reflector, 9... Lamp housing, 9a Slit 0 Agent's name Patent attorney Toshio Nakao and 1 other person Figure 1 Figure 2 Figure 1 Ants 9th grade: Department Hun 1 Figure 3 4 Figure 4 Engineering

Claims (1)

[Claims] A fluorescent light source illuminates the document placed on the stationary platen glass.
It is provided with means for scanning by moving an optical system that forms an image on a reflecting mirror and has a lens and a reading element, and is located between the document table glass and the fluorescent light source and outside the document reading area and at both ends of the fluorescent light source. A document reading device equipped with a white reflective plate at a position opposite to the paper.