JPH067616Y2 - Original illumination device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a document illuminating device using a U-shaped light source as a light source for illumination.

(Prior Art) In an image reading apparatus such as an image scanner or a facsimile, a fluorescent lamp is used as a light source for illuminating a document, but when a U-shaped fluorescent lamp is used for the purpose of downsizing and efficiency of the apparatus. There is.

FIG. 3 shows the configuration of a reading device using such an illuminating device. Reference numeral 1 is an original document placed on the contact glass 2 and is illuminated by a U-shaped fluorescent lamp 3. Manuscript 1
The reflected image from is reflected by the mirrors 4, 5 and 6 through the gap of the parallel part of the fluorescent lamp 3, is imaged by the lens 7, and is converted into an electric signal by the photoelectric conversion device 8. The fluorescent lamp 3 and the mirror 4 move integrally in the direction of arrow A (sub-scanning direction) to scan the entire surface of the document. Mirrors 5 and 6 are mirrors 4
Move in the same direction with a movement distance of 1/2 relative to the mirror 4
The distance between the photoelectric conversion device 8 and the photoelectric conversion device 8 is always kept constant. The main scanning direction is the direction perpendicular to the arrow A direction, but the main scanning is performed by the photoelectric conversion device 8 (in this case, CC
D) by self-scanning.

Here, the light incident on the photoelectric conversion device 8 must be diffused reflection light on the document surface. This is because in the case of strong direct reflected light (referred to as specular reflected light) from the document surface as shown by B in FIG. 4, the reflected light is not proportional to the image information on the document surface. Therefore, the incidence of such specular reflection light must be avoided as much as possible.

However, as shown in FIG. 5, the light emitted from the bent portion 3a of the U-shaped fluorescent lamp 3 strikes the surface of the document 1, and the specularly reflected light has a locus as indicated by arrows C and D. This specularly reflected light is U
Since the light is reflected by the mirror 4 through the gap between the parallel portions of the letter-shaped fluorescent lamp 3, it is incident on the photoelectric conversion device 8 and the image information cannot be read accurately.

In order to prevent such a problem, it is sufficient to enlarge the holding portion 9a of the holding metal member 9 for holding the bent portion of the fluorescent lamp so as to shield the light. As a result, the effective use length of the light source is shortened.

(Object of the Invention) The present invention provides an original illuminating device that does not reduce the effective reflected light and prevents specular reflected light from entering the photoelectric conversion device.

(Structure of the Invention) In order to achieve the above object, light-shielding masking is applied to the peripheral wall of the tube in the bent portion of the U-shaped light source, where the gap portion of the parallel portion is extended.

According to the above configuration, since the light is not emitted from the bent portion of the light source, which corresponds to the main scanning line, the specularly reflected light does not enter the photoelectric conversion device, and the effective reflected light is utilized to the maximum extent. it can.

(Example) Hereinafter, an example will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention, which is a U-shaped fluorescent lamp 3
In the bent portion 3a, a masking 11 for light shielding is applied to the peripheral wall of the tube at a portion where the gap between the parallel portions is extended. FIG. 2 shows a cross section of the masking portion. As the light-shielding masking 11, an opaque and heat-resistant tape is wrapped around the pipe peripheral wall, or a light-shielding paint is applied.

In the present embodiment configured as described above, there is no light that illuminates the document from directly above the main scanning line when reading the document, so that the specularly reflected light of the reflected light that illuminates the document does not reach the mirror 4. . That is, the reflected light that reaches the photoelectric conversion device 8 is only irregularly reflected light.

The fluorescent lamp 3 is fixed by a metal fitting or the like, and is attached or detached for maintenance. At that time, the tube wall is made of glass, and it is a fluorescent lamp that repeats thermal expansion and contraction when turned on and off. Do not scratch it. Therefore, fixing the masked portion according to the present invention is extremely preferable from the viewpoint of protecting the tube wall.

(Effects of the Invention) As described above, according to the present invention, it is possible to prevent the specularly reflected light of the illumination light from entering the photoelectric conversion device, and as a result, it is possible to read the original image information faithfully. You can
Further, by holding the masking portion when holding and fixing the light source, the light source can be protected and the life can be extended.

[Brief description of drawings]

FIG. 1 is a plan view of a U-shaped light source according to an embodiment of the present invention, FIG. 2 is a sectional view of the bent portion, and FIG. 3 is a configuration diagram of a reading device using a U-shaped fluorescent lamp. FIG. 4 is a diagram showing specular reflection light, and FIG. 5 is a diagram showing a case where specular reflection light of light emitted from a bent portion of a light source enters a photoelectric conversion device. 3 ... U-shaped fluorescent lamp, 3a ... bent, 11 ... masking for light shielding.

Claims (1)

[Scope of utility model registration request] 1. An image reading apparatus using a U-shaped light source as a light source for illuminating an original, wherein a light-shielding masking is applied to a peripheral wall of a portion of the bent portion of the U-shaped light source which extends a gap between parallel portions. Original illumination device characterized by.