JPH089967Y2 - Document reader - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for illuminating an original surface with an illumination light source, that is, an illuminating device using a fluorescent lamp as a light source, and reading the original surface with the reflected light. Relates to improvement of a lighting device such as a copying machine.

(Prior Art) Conventionally, a fluorescent lamp has been used as an illumination device of a copying machine, and the relationship between the fluorescent lamp and a document is shown in FIG. The document 2 placed on the contact glass 1 is provided with a slit (not shown) provided between the fluorescent lamps 3 and 3'and the contact glass 1 in the longitudinal direction of the fluorescent lamps 3 and 3 '(main scanning). Direction), and the light reflected from the document surface 2a is imaged on the light receiving surface of the image sensor, which is a photoconductor, through the mirror and the lens group.

FIGS. 3 and 4 are diagrammatically illustrated for easy understanding of the irradiation state on the document surface in relation to the light and shade of the document surface 2a in the main scanning direction A which is the length direction of the fluorescent lamp. The length direction of the fluorescent lamp 3 is defined as the main scanning direction A, and the document feeding direction perpendicular to the length direction of the fluorescent lamp 3 is defined as the sub scanning direction B.

In the case of FIG. 3, the surface of the document surface 2a in the main scanning direction A is white, and in the case of FIG. 4, the surface of the document surface 2a in the main scanning direction A is a mixture of white and black. When the original surface 2a in the figure is white and when the original surface 2a in FIG. 4 is a mixture of white and black, the reflection of the point b on the original surface b of the same color due to the flare light is reflected. The light intensities are different, and different densities are detected by the image sensor that forms the original image.

That is, the document surface 2a is white in the main scanning direction A
In the case of FIG. 2A, since the light from one point a of the fluorescent lamp is diffused light, in addition to the point b on the document surface 2a, the points c on both sides of the point b,
It is distributed on the radiation at points d, etc. (shown by the solid line).
The light from one point a of the fluorescent lamp illuminates a considerable area of the document surface 2a around the point b of the document surface 2a that receives the light from the point a vertically, and the point c of the document surface 2a is white. Therefore, the light irradiating the point C is diffusely reflected and travels in each direction indicated by the dotted line in the figure. Part of the reflected light is incident on the fluorescent lamp 3, is reflected again at the reflection layer f point in the fluorescent lamp, and illuminates the point b on the document surface 2a. When the points c and d around the point b on the document surface 2a are white, the light illuminating the point b includes the reflection component of the light illuminating the document surface 2a other than the point b. This component of light is called flare light here.

In FIG. 4, the manuscript surface 2a has a white point b and both sides of the point c and d.
In the case where the black dots are mixed, as in the case of FIG. 3, the light from one point a of the fluorescent lamp 3 is b on the document surface 2a.
Irradiate a considerable area on either side of the point. Since points C and d on both sides are black portions, points c and d on the document surface 2a
Since there is no reflection from the point, the flare light component of the light illuminating the point b depends on the white part near the point b, and c
It is not affected by points and d.

Thus, although the points b on the document surface 2a are all the same white, the intensity of the reflected light from the point b on the document surface 2a depends on the colors on both sides of the point b on the document surface 2a. Different,
As a result, the image sensor detects different densities, and the point b in FIG. 3 is detected as white, but the point b in FIG. 4 is detected as having a small amount of reflected light and having a certain density. Has a black and dirty color.

(Purpose of Invention) The present invention solves the above-mentioned conventional drawbacks.
An object of the present invention is to provide a device capable of correctly reading the density of a document surface by blocking flare light in the length direction of the fluorescent lamp, that is, the main scanning direction due to re-reflection inside the fluorescent lamp used as an illumination light source.

(Constitution of the Invention) The present invention is directed to an illumination light source provided in parallel with the main scanning direction for scanning the document surface, and an irradiation light slit provided between the illumination light source and the document surface along the main scanning direction. A slit for reflected light provided along the main scanning direction between the document surface and the light receiving element, and the slit portion for irradiation light when the document feeding direction orthogonal to the main scanning direction is the sub-scanning direction. A partition plate at least perpendicular to the main scanning direction and parallel to the sub-scanning direction, the partition plate having a shape that does not block the reflected light from the document surface passing through the reflected light slit. It is characterized by that.

Further, it is desirable that the surface of the partition plate is a substantially non-reflective surface.

Further, it is desirable that the partition plates be provided at predetermined intervals.

 Hereinafter, a preferred embodiment of the present invention will be described.

FIG. 1 is a block diagram of the present invention. Contact glass 1
The original 2 placed on the table is the illumination light source 3, which is a fluorescent lamp,
Illuminated by 3 '. The reflected light from the original 2 is imaged on the light receiving surface of the image sensor, which is a photoconductor, through a mirror group and a lens group (not shown) by the mirror 4. At this time, the original image is formed on the image sensor by the scanning in the main scanning direction A while the original is moved in the sub scanning direction B. Between the contact glass 1 supporting the original 2 and the illumination light sources 3, 3 ', slit members 6, 6'for restricting the light flux width in the main scanning direction are provided and slits are formed.

The partition plates 5 and 5'in the present invention are arranged between the reading slit members 6 and 6'and the illumination light sources 3 and 3 '. Also,
The partition plates 5 and 5'are formed and arranged so as not to block the reflected light from the document surface 2a guided to the light receiving surface via the mirror 4. The layout of the partition plate 5 between the one light source 3 and the original 2 is shown in the schematic views of FIGS. 2 (a) and 2 (b) for easy understanding. In order to prevent the influence of light and dark at points c and d located on both sides of the original surface point b in FIG. 4, it is perpendicular to the length direction of the fluorescent lamp, that is, the main scanning direction A and constant in the sub scanning direction B. They are arranged in parallel with an interval l.

Therefore, the light from the point a of the fluorescent lamp 3 is limited by the partition plate 5 at a constant interval, so that the light on both sides of the point b on the original surface in FIGS. It is possible to detect the light and darkness of the point b on the document surface and to largely remove the flare light component. Therefore, when the document surface is white in the main scanning direction and when it is white or black. It is possible to suppress the difference in the detected density between the case where the part is mixed and the case where the part is white, to be small.

If the partition plates 5 and 5'are thick, the shadow of the partition plate will be formed on the document surface, so it is preferable to use a very thin partition plate. Also, it is preferable to use a pitch of about 10 mm as the dimension l of the partition plates. I got the result.

It is desirable that the surface of the partition plate 5 be a substantially non-reflective surface by applying black coating or the like. This prevents the generation of new flare light due to the light reflected from the surface of the partition plate.

Table 1 shows data when the partition plate of the present invention is provided and before the partition plate is provided. The chart used as the manuscript is as follows.

1 ... Full white chart 2 ... Chart in which a white band with a width of 6 mm extends in the sub-scanning direction in addition to black (see FIG. 6 (A)) 3 ... Same as 2, but the width of the white portion With 3 mm (See Fig. 6 (b)) (l = 10 mm, all are the same) The numbers in the table represent the white area of each chart with the read value (mV) of the output of the image sensor. . ()
The numbers inside are the output ratio when the entire surface is white.

As can be understood from Table 1, the effect of flare light can be reduced by providing a partition plate as in the present invention.

(Effect of the invention) By providing the partition plate according to the present invention, the influence of flare light can be reduced, so that the density information of the original at the time of copying can be
It has the effect that it can be more faithfully obtained from the original.

Further, in addition to the slit for irradiating the document surface with the illumination light, the slit for irradiating the light receiving element with the reflected light reflected by the document surface is provided, so that the influence of flare light in the document feeding direction of the document can be reduced. it can.

In addition, the partition plate has a shape that does not block the reflected light from the original, and because the reflected light does not shade the partition plate, it does not adversely affect the read image and guides the reflected light to the light receiving surface efficiently. You can

Further, since the light source can be arranged near the document surface and the illumination angle can be made closer to vertical, the size of the apparatus can be reduced and the illumination efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 (a) (b) is a schematic side view and front view showing the relationship between a partition plate, an original and an illumination light source of the present invention, and FIG. 3 (a) (b). ) And FIG. 4 (a) (b) are schematic side and front views showing the relationship between a conventional document and an illumination light source, FIG. 5 is a configuration diagram of a conventional illumination unit, and FIG. 6 (a) (b). FIG. 3 is a diagram of Charts 2 and 3 shown in Table 1. 1 ... Contact glass, 2 ... original document, 3,3 '... fluorescent lamp, 4 ... mirror, 5 ... partition plate, 6,6' ... slit member.

Claims (3)

[Scope of utility model registration request] 1. An illumination light source provided in parallel with a main scanning direction for scanning an original surface, an irradiation light slit provided along the main scanning direction between the illumination light source and the original surface, and an original surface. And a light-receiving element, a slit for reflected light provided along the main scanning direction, and, when a document feeding direction orthogonal to the main scanning direction is a sub-scanning direction, at least the irradiation light slit portion, A thin plate that is perpendicular to the main scanning direction and parallel to the sub-scanning direction and that has a shape that does not block the reflected light from the document surface that passes through the reflected light slit. Document reading device. 2. The document reading device according to claim 1, wherein the surface of the partition plate is a substantially non-reflective surface. 3. The document reading device according to claim 1, wherein the partition plates are provided at predetermined intervals.