JPH09326903A - Original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the entire irradiation distribution flat, to improve the light collection efficiency and to suppress image disturbance due to an external disturbance light by passing a reflected light between 1st and 2nd reflecting plates and making the light from a lamp irradiate an object position of an original efficiently. SOLUTION: A reflected light from an original G passes between 1st and 2nd reflecting plates 11, 12 and is led to a CCD sensor 3 via 1st, 2nd, 3rd mirrors 21, 22, 23 and a lens 30 and read in the subscanning direction, Furthermore, the 1st and 2nd reflecting plates 11, 12 having a mirror surface before and after the subscanning direction are arranged around an irradiation optical axis from a lamp 10 toward an object position P of the original G placed on a platen glass 2. Then the distribution of the light from the lamp 10 irradiating the original G directly is a projected shape and the reflected light from the reflecting plates 11, 12 is recessed. Thus, the entire irradiation distribution is made flat, the light collection efficiency is improved and image disturbance in a sensor by an external disturbance light is suppressed. Even when the position of the sensor is changed, the illuminance change is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading apparatus which irradiates a read document with predetermined light and receives the reflected light by a linear light receiving element.

[0002]

2. Description of the Related Art In a document reading device such as a copying machine or a scanner, a document to be read is irradiated with light from a light source along the main scanning direction of the document surface, and the document or the light source is moved in the sub scanning direction. The CCD sensor receives the reflected light.

FIG. 9 is a diagram for explaining a first conventional example, FIG.
Is a diagram illustrating a second conventional example, FIG. 11 is a diagram illustrating a third conventional example, and FIG. 12 is a diagram illustrating a fourth conventional example. For convenience of explanation, the outer diameter will be 8 mm in the following.
The case of using a fluorescent lamp with an opening angle of 75 degrees will be described as an example, but the present invention is not particularly limited to this condition.

In the first conventional example shown in FIG. 9A, a lamp 10 which irradiates light with a target position P of an original G placed on the platen glass 2 as a center, and light from the lamp 10 And a reflector 11 ′ that reflects and irradiates the target position P.

As shown in FIG. 9B, in the document reading apparatus of the first conventional example, the light collection efficiency with respect to the position in the sub-scanning direction is about 3.8% at maximum.

In the second conventional example shown in FIG. 10 (a), the lamp 10 which irradiates light around the target position P of the document G placed on the platen glass 2 and the light which reflects the light. The configuration including the reflection plate 11 ′ for irradiating the target position P with the target position P is similar to that of the first conventional example, but is different in that the distance between the lamp 10 and the document G is closer than that of the first conventional example. .

As shown in FIG. 10B, in the document reading apparatus of the second conventional example, the light collection efficiency is higher than that of the first conventional example because the distance between the lamp 10 and the document G is reduced. Although it is increasing, the distribution is more convex,
In addition, the return light from the manuscript is also likely to be adversely affected.

A third conventional example shown in FIG. 11 (a) is disclosed in Japanese Patent Laid-Open No. 4-323951, and the target position P of the original G placed on the platen glass 2 is set at the target position P. Two lamps 10a, 10b for irradiating light toward
And a light shielding plate 13 provided from each of the lamps 10a and 10b toward the target position P.

In the document reading apparatus of the third conventional example,
In order to read the information of the document G accurately without being affected by the return light from the document, the light (disturbance light) from other than the lamps 10a and 10b is shielded by the light shielding plate 13, and the lamp 1
Only the light from 0a and 10b is applied to the target position P.

Since such a light-shielding plate 13 is provided, as shown in FIG. 11B, in the document reading apparatus of the third conventional example, the first conventional example (see FIG. 9B). The light collection efficiency is higher than that of the second conventional example (see FIG. 10B). On the other hand, the distribution of the convex shape is stronger than that of the second conventional example.

Further, the fourth conventional example shown in FIG. 12A is provided with two lamps 10a and 10b for irradiating the target position P of the original G placed on the platen glass 2 with light. In particular, the configuration does not have a reflector as in the first conventional example and the second conventional example, or a light shielding plate as in the third conventional example.

As shown in FIG. 12B, in the document reading apparatus of the fourth conventional example, two lamps 10a and 10b are provided.
The light-collecting efficiency is higher than that of the first and second conventional examples due to the provision of the above, and the light-collecting efficiency is lower than that of the third conventional example because the light shielding plate is not provided. Further, as for the distribution, the convex type is weaker than the first to third conventional examples because no reflection plate or light shielding plate is provided.

[0013]

By the way, FIG. 7 is a diagram showing a difference in relative illuminance distribution, and FIG. 8 is a diagram showing relative illuminance with respect to a sub-scanning movement amount. In the document reading apparatus, the viewpoint position of the CCD sensor at the sub-scanning start position and the end position (hereinafter, simply referred to as the sub-scanning position) due to the distortion of the mounting rail and the error in the squareness of each mirror in the movement of the light source or each mirror along the sub-scanning direction. The viewpoint position) moves.

Arrow A shown in FIG. 7 indicates the viewpoint position at the scanning start position in the sub-scanning direction, and arrow B indicates the viewpoint position at the scanning end position. When the viewpoint position shifts from A to B as described above, for example, in the relative illuminance distribution shown by the solid line in FIG. 7, the illuminance greatly changes from the start of scanning to the end of scanning. The change in illuminance is shown by the solid line in FIG.

On the other hand, in the relative illuminance distribution shown by the broken line in FIG. 7, the change in illuminance from the start of scanning to the end of scanning is small. In this case, as shown by the broken line in FIG. 8, the change in the relative illuminance is small over the entire sub-scanning movement amount.

Further, in the document reading apparatus, it is desired to efficiently collect the light emitted from the lamp onto the document surface to improve the S / N and efficiently use the electric power.

From the above, in the first conventional example shown in FIG. 9, the light collection efficiency is insufficient and it is difficult to improve the S / N. Further, in the second conventional example shown in FIG. 10, since the distance between the lamp 10 and the document G is shortened in order to improve the light collection efficiency, the illuminance distribution has a strong convex shape, and the change in illuminance due to the change in the viewpoint position changes. It becomes big and the ambient light is also large.

Furthermore, in the third conventional example shown in FIG.
Although the illuminance is increased, the light is absorbed by the light shielding plate 13 and the convex shape of the illuminance distribution becomes very strong, and even a slight change in the viewpoint position causes a large change in the illuminance. Further, also in the fourth conventional example shown in FIG. 12, although the illuminance is high, the light collection efficiency is 25% per line, which is very poor.

[0019]

SUMMARY OF THE INVENTION The present invention is a document reading apparatus made to solve such a problem. That is, according to the present invention, light is irradiated to a reading target position along the main scanning direction in reading an original by the linear light receiving element, and the irradiation position of this light is set along the sub scanning direction in reading the linear light receiving element. Move relative to
In a document reading device in which a linear light receiving element receives reflected light from a document at a reading target position, an irradiation unit that irradiates a predetermined light to a reading target position of the document along the main scanning direction, and a reading target from the irradiation unit. And a pair of reflectors arranged in the front-rear direction in the sub-scanning direction about the irradiation optical axis toward the position.

With such a pair of reflecting plates, in addition to the light directly radiated from the irradiating means onto the document surface, the reflected light from each reflecting plate is radiated onto the document surface. Since the illuminance distribution of the reflected light from the pair of reflecting plates is a substantially concave type centered on the target position of the document, it is flat as a whole together with the substantially convex type illuminance distribution of the light directly irradiated from the irradiation means. It becomes possible to obtain the illuminance distribution.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a document reading apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a document reading apparatus according to this embodiment, and FIG.
FIG. 3 is a diagram illustrating an embodiment, FIG. 3 is a diagram illustrating a second embodiment, FIG. 4 is a diagram illustrating a third embodiment, and FIG. 5 is a diagram illustrating an illuminance distribution in the sub-scanning direction in the second and third embodiments. Is.

First, the configuration of the document reading apparatus in this embodiment will be described with reference to FIG. This document reading device 1
Irradiates the original G with light from the lamp 10 while the original G is placed on the platen glass 2 to read the CCD sensor 3 in the main scanning direction (vertical direction in the drawing) in the sub-scanning direction (arrow direction in the drawing). ) Is done continuously along.

As the document reading device 1 in this embodiment, a lamp 1 for irradiating a predetermined position on the document G along the main scanning direction in reading by the CCD sensor 3 with a predetermined light.
0, and a first reflection plate 11 and a second reflection plate 12 that are arranged in the front and rear in the sub-scanning direction around the irradiation optical axis from the lamp 10 to the target position of the document G.

Further, the reflected light from the document G passes between the first reflector 11 and the second reflector 12 and passes through the first mirror 2
1, second mirror 22, third mirror 23 and lens 30
It reaches the CCD sensor 3 via. For reading along the sub-scanning direction, the lamp 10, the first reflector 11, the second
The reflector 12 and the first to third mirrors 21, 22, and 23 are respectively moved in the sub-scanning direction, and the light irradiation position on the original G is moved in the sub-scanning direction (movements A to B in the figure). The CCD sensor 3 sequentially receives the reflected light associated with the above, and reads the information of the document G.

Next, the first embodiment will be described. FIG.
(A) shows the arrangement of the lamp 10, the first reflector 11 and the second reflector 12 of the first embodiment, and (b) shows one lamp within the unit width at the position in the sub-scanning direction on the platen glass. It indicates how much of the light flux is condensed (light collection efficiency).

As shown in FIG. 2A, in the first embodiment, the front and rear in the sub-scanning direction are centered on the irradiation optical axis from the lamp 10 to the target position P of the original G placed on the platen glass 2. The first reflection plate 11 and the second reflection plate 12 are arranged in the. Mirror surfaces are used as the reflecting surfaces of the first reflecting plate 11 and the second reflecting plate 12.

The distribution of the light emitted from the lamp 10 directly to the original G is substantially convex as shown by the broken line in FIG. 2 (b). On the other hand, the first reflector 11 and the second reflector 1
The distribution of the reflected light from 2 and 2 is substantially concave as shown by the alternate long and short dash line in FIG. The first reflection plate 11 and the second reflection plate 12 are arranged at such an angle that the distribution of reflected light is substantially concave.

Therefore, the lamp 10 and the first reflector 11
Also, the distribution of the light emitted from all of the second reflection plate 12 to the original G is the sum of the distributions of the broken line and the alternate long and short dash line in FIG. 2B, and has the shape shown by the solid line. When the lamp 10 having the same shape as that of the conventional example having the light collecting efficiency of 3.8% is used at the same position, the light collecting efficiency of 4.4% can be obtained in the first embodiment. Moreover, the overall illuminance distribution is flatter than that of the lamp 10 alone.

Further, as described above, the first reflector 1
Since mirror surfaces are used as the reflecting surfaces of the first and second reflecting plates 12, the first and second reflecting plates 11 and 12 are
Even if is placed near the document G, the light returning from the document G does not affect the reflected light on the reflection surface (no disturbance light is generated due to diffusion), and the CCD sensor Image distortion can be suppressed.

Next, the second and third embodiments will be described. In the second embodiment shown in FIG. 3, two lamps 10a and 10b, each of which has a different irradiation angle, are arranged toward the target position P of the document G placed on the platen glass 2 and are arranged in front and behind in the sub-scanning direction. It has a configuration including a first reflector 11 and a second reflector 12.

Further, in the third embodiment shown in FIG. 4, the second
As in the embodiment, the two lamps 10a and 10b, and the first
Although the configuration includes the reflector 11 and the second reflector 12, the lamps 10a and 10b and the first reflector 11,
The difference is that the distance between the second reflectors 12 is closer than in the second embodiment.

FIG. 5 shows the sub-scanning direction illuminance distributions in the second and third embodiments and the sub-scanning direction illuminance distributions in the first conventional example and the fourth conventional example, respectively. That is, in the second embodiment and the third embodiment, the light collection efficiency is higher than the light collection efficiency (2.5%) of the fourth conventional example, and the light collection efficiency of one lamp ( A value close to 3.8%) has been achieved. This shows the effect of the two lamps 10a and 10b and the first reflector 11 and the second reflector 12.

Further, the same change of the viewpoint position as in FIG.
In the case of B), the illuminance distribution is sufficiently flat in this range, and it is possible to achieve both improvement of the light collection efficiency.

That is, in the second and third embodiments, the distribution angle of the reflected light is made substantially concave by adjusting the arrangement angle between the first reflector 11 and the second reflector 12, and the two lamps 10a, A substantially flat distribution is realized by adding it to the distribution of the substantially convex light emitted from 10b.

In the second and third embodiments, two lamps 10a and 10b are used, but two or more lamps may be used. In this case, the originals are directly supplied from the lamps. The angles of the first reflector 11 and the second reflector 12 are adjusted according to the distribution of the light irradiated to
It suffices to be able to obtain both the light collection efficiency and the flattening of the distribution.

The first reflector 1 used in each embodiment
The reflecting surfaces of the first and second reflecting plates 12 on the platen glass 2 side are made to be the same plane as the reflecting surface of the central portion. That is, the first reflector 11 and the second reflector 1
Since the angle and shape of the reflecting surface of the part near the platen glass 2 of 2 have a great influence on the illuminance distribution, it is easy to achieve the illuminance distribution as intended by making this part the same plane as the central part. And the first reflector 11
The distribution of the reflected light by the second reflection plate 12 can be made substantially concave.

Specifically, as shown in FIG. 6 (a), the flat first reflector 11 and the second reflector 12 are attached to the angle 31, or as shown in FIG. 6 (b), L When the first reflector 11 and the second reflector 12 that are folded into a mold are attached to the angle 31, the bent portion is on the lamp 10 side.

As a result, the reflection surfaces of the first reflection plate 11 and the second reflection plate 12 on the platen glass 2 side can be made flush with the reflection surface of the central portion.

[0039]

As described above, the document reading apparatus of the present invention has the following effects. That is, by arranging the irradiation means, the first reflection plate and the second reflection plate as in the present invention, it is possible to efficiently irradiate the target position of the document with light and to make the illuminance distribution flat. Even if the viewpoint position of the sensor changes due to the sub-scan, it is possible to reduce the change in illuminance.

In addition, since the light collecting efficiency is increased, the distance between the light source and the original can be increased, the adverse effect on the light source due to the returning light from the original can be reduced, and the information of the original can be read accurately. .

Further, by using the first reflecting plate and the second reflecting plate together with the plurality of light sources, the illuminance can be further improved and the illuminance distribution can be flattened, and the S / N can be improved. In the above, the document reading device of the type in which the light source moves has been described as an example, but the same effect can be obtained also in the document reading device of the type in which the document moves.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a document reading apparatus according to the present embodiment.

FIG. 2 is a diagram illustrating a first embodiment.

FIG. 3 is a diagram illustrating a second embodiment.

FIG. 4 is a diagram illustrating a third embodiment.

FIG. 5 is a diagram showing an illuminance distribution in the sub-scanning direction in the second and third embodiments.

FIG. 6 is a schematic cross-sectional view showing a mounting example of a reflection plate.

FIG. 7 is a diagram showing a difference in illuminance distribution.

FIG. 8 is a diagram showing a change in CCD output with respect to a sub-scanning direction.

FIG. 9 is a diagram illustrating a first conventional example.

FIG. 10 is a diagram illustrating a second conventional example.

FIG. 11 is a diagram illustrating a third conventional example.

FIG. 12 is a diagram illustrating a fourth conventional example.

[Explanation of symbols]

 1 Original Reading Device 2 Platen Glass 3 CCD Sensor 10 Lamp 11 First Reflector 12 Second Reflector 21 First Mirror 22 Second Mirror 23 Third Mirror 30 Lens G Original

Claims (4)

[Claims] 1. A light is irradiated to a reading target position along a main scanning direction in reading an original by a linear light receiving element, and the light irradiation position is set along the sub scanning direction in reading the linear light receiving element. In a document reading device that moves relative to a document and receives reflected light from the document at the reading target position by the linear light receiving element, a predetermined reading target position of the document along the main scanning direction is provided. An original document characterized by comprising: an irradiating unit for irradiating the above-mentioned light; and a pair of reflecting plates arranged before and after in the sub-scanning direction with respect to an irradiating optical axis from the irradiating unit toward the reading target position. Reader. 2. The pair of reflectors are arranged at an angle such that an illuminance distribution in the sub-scanning direction due to reflected light from the reflectors becomes substantially concave when centered on the reading target position. The document reading apparatus according to claim 1, wherein: 3. The document reading apparatus according to claim 1, wherein a reflecting surface on the platen glass side of each of the pair of reflecting plates is the same plane as a surface of a central portion of the reflecting plate. . 4. The document reading apparatus according to claim 1, wherein the irradiation unit is composed of a plurality of light sources having different irradiation angles of light to the target position. .