JP2002125098A - Line illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line illuminating device capable of efficiently converging scattered lights on an original reading face. SOLUTION: A light guiding part 11 for guiding a light from a light source such as a light emitting diode to a longitudinal direction (main scanning direction) and for generating scattered lights according to a light scattering pattern P, and a light converging part 12 for converging the scattered lights outgoing from the light guiding part on an original reading face, are independently formed and housed in a light guiding body case 13, so that the light guiding part 11 and the light converging part 12 are brought into contact with each other. The light scattering pattern P is set at the focal position of a reflecting curved surface constituted of an elliptic face. In this case, the cross-section of the light guiding part is narrowed, and the density of a light propagating inside the light guiding part is improved so that the strength of the scattered lights can be improved. Also, the light converging part can be set by giving the light converging efficiency as a priority over the size and shape so that the light converging efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a line illuminator used for a contact image sensor (CIS).

[0002]

2. Description of the Related Art A contact-type image sensor has a smaller number of parts than an image sensor of a reduction optical system, and the sensor of an optical component and a lens array can be arranged close to each other. is there. For this reason, the contact type image sensor is used as a device for reading a document by a facsimile, a copier, a scanner, or the like. The contact type image sensor is provided with a line illuminating device for linearly illuminating the original reading surface in the main scanning direction. As the line lighting device, a device using a light guide is known.

FIG. 11 is a cross-sectional view of a conventional image sensor having a line illumination device, FIG. 12 is a diagram showing an example of a cross-sectional shape of a conventional light guide, and FIGS. 13 and 14 are specific examples of light scattering patterns. FIG.

As shown in FIG. 11, a contact image sensor 101 has a housing 102, a line illuminating device 110 is incorporated in the housing 102, and a lens array (rod) as an equal-magnification image forming lens is provided in the housing 102. A lens array (103) is arranged, and a sensor substrate (105) provided with a line image sensor (photoelectric conversion element) (104) below the housing (102) is attached. The line lighting device 110 includes a light guide 111, a light guide case 112,
A light emitting source substrate provided with a light emitting source (not shown). The close contact type image sensor 101 makes the outgoing light (illumination light) emitted from the outgoing surface 111 a of the light guide 111 enter the reading surface of the original through the cover glass 106, and reflects the reflected light via the lens array 103. The original is read by the detection by the line image sensor 104.

The light guide 111 is made of glass, transparent resin, or the like. As shown in FIG. 12, the cross-sectional shape in a direction orthogonal to the length direction of the light guide 111 is substantially 1/4.
The ellipse has a shape in which the long-axis end is chamfered. FIG.
FIG. 12A is a straight line including the focal point of the ellipse, which is chamfered to the major axis side end of the approximately 1/4 ellipse at 45 degrees, and FIG. 12B is 90 degrees with respect to a straight line parallel to the major axis direction of the ellipse. Is shown. Reference numeral 111a denotes an emission surface parallel to the minor axis of the ellipse, reference numeral 111b denotes a surface parallel to the major axis of the ellipse, reference numeral 11
1c is a reflection curved surface (elliptical surface), and reference numeral 111d is a chamfered surface.

The light guide 111 has a light scattering pattern P for generating scattered light. FIG. 13 shows an example in which a light scattering pattern P is formed on a plane parallel to the major axis direction of the ellipse of the light guide 111. FIG. 14 shows an example in which a light scattering pattern P is formed on the chamfered surface of the light guide 111.
The light scattering pattern P is formed by printing a white paint. The light scattering pattern P may be formed by roughening the surface of the light guide 111 by, for example, laser processing.

[0007] A light-emitting source substrate (not shown) is attached to the longitudinal end face of the light guide 111.
On a light-emitting source substrate (not shown), for example, one or more surface-mounted light-emitting diodes (LEDs) are mounted as light-emitting sources. The light source may be provided on both sides of the light guide 111, or may be provided only on one side of the light guide 111.

Illumination light (incident light) from a light source (not shown)
Is incident on the inside of the light guide 111 from the end face of the light guide 111. The incident light is guided in the longitudinal direction while being reflected on the inner surface of the light guide 111. The light guided in the longitudinal direction is scattered by the light scattering pattern P, and the scattered light is emitted as emission light.

The conventional line illuminating device 110 includes the light guide 1
11 is covered with, for example, a white light guide case 112,
The light leaked to the outside is reflected by the light guide case 112 and returned to the inside of the light guide 111, thereby reducing the loss of scattered light,
This improves the intensity of the emitted light. Further, by changing the arrangement interval and area of the light scattering pattern P in accordance with the distance from the light emitting source 113, the intensity of the emitted light becomes uniform in the longitudinal direction (main scanning direction) of the light guide. Like that. Further, by providing the light guide 111 with a reflection curved surface 111c formed of an elliptical curved surface and forming a light scattering pattern P near the focal position of the ellipse, the scattering scattered by the light scattering pattern P as shown in FIG. The light is reflected by the reflection curved surface 111c and is condensed on the document reading area (the document reading surface immediately above the lens array 103).

[0010]

In order to increase the light-condensing efficiency on the irradiation surface (original surface) by using a light guide having an elliptical cross section, the elliptical surface is made deeper and more scattered light from the focal position is obtained. It is necessary to reflect and condense. However, in this case, since the cross-sectional area of the light guide increases, the density of the propagating light inside the light guide decreases, and there is a trade-off that the intensity of the scattered light generated in the light scattering pattern decreases. That is, the conventional light guide has a light guiding / light scattering function of generating scattered light by a light reflection pattern while guiding light incident from an end face in a longitudinal direction, and a reflection curved surface (elliptical surface) of scattered light. Since the light condensing function of condensing outgoing light on the document surface by reflecting and exiting from the exit surface is composed of a single member, the light guiding / scattering performance and the light condensing performance are improved. Is difficult to achieve independently.

In order to increase the amount of emitted light, a method of increasing the area of the light scattering pattern has been conventionally used. However, since it is necessary to ensure uniformity of the light intensity in the main scanning direction, the length dimension (dimension in the main scanning direction) of the light scattering pattern is restricted. It is conceivable to increase the width of the light scattering pattern (reference numeral W in FIG. 14). However, the flatter the ellipse, the greater the divergent light other than the light converging point.
It does not contribute much to increasing the amount of light.

FIG. 3 shows light intensity characteristics when the light guide 111 shown in FIG. 14 is incorporated in the contact type image sensor 101 shown in FIG. The light guide 111 has a major axis of 10.6.
mm, the minor axis is a quarter ellipse of 3.5 mm, and the chamfer width is 0.6 mm. The thickness of the cover glass 106 is 4 m
m, the spatial distance between the light guide emission end and the cover glass is 2.5
mm. In FIG. 3, the horizontal axis of the graph is the displacement in the sub-scanning direction, and the optical axis position of the lens array 103 is 0,
The light guide 111 side is indicated by a negative value, and the opposite side is indicated by a positive value. The vertical axis of the graph is the light intensity, which indicates the light intensity on the original reading surface. The characteristics indicated by circles indicate light intensity characteristics when the width W of the light scattering pattern P is 0.3 mm, and the characteristics indicated by squares indicate light intensity when the width W of the light scattering pattern P is 0.6 mm. It is a characteristic. in this case,
Even if the width of the light scattering pattern P is increased, the scattered light from the position largely shifted from the focal point of the ellipse is diffused without being collected at the intersection between the original reading surface and the optical axis of the lens array 103. As a result, the light intensity at the intersection (the position where the displacement in the sub-scanning direction is 0) is rather reduced.

On the other hand, the light condensing point (lens array 103)
In order to converge light with high accuracy on the original reading surface just above the optical axis (the original reading surface), it is better that the ellipse is not flat to some extent (closer to the circle) and the size is larger. The one that is not flat has a tolerance for the shift of the focal position of the scattering point, and even if the width of the light scattering pattern is increased, it contributes to an increase in the amount of light at the condensing point to some extent. However, there is a problem that the scattered light is not totally reflected on the elliptical curved surface when approaching a circle. In addition, if the size of the light guide is increased, it takes a long time to form the light guide, which causes a problem that "sink" is likely to occur.

The present invention has been made to solve such a problem, and by increasing the density of light propagating inside a light guide, strong scattered light is generated even in a light scattering pattern having a small width. It is another object of the present invention to provide a line illumination device capable of efficiently condensing the scattered light on a document reading surface.

[0015]

In order to solve the above problems, a line illuminating device according to the present invention guides light from a light source incident from an end face in a longitudinal direction and is formed along the longitudinal direction. A light guide that scatters light by a light scattering pattern and emits light from an emission surface formed along the longitudinal direction, and a light collector that collects light emitted from the emission surface of the light guide on a reading surface of a document. And the light guide unit and the light collecting unit are arranged in close contact or close proximity.

The line illuminating device according to the present invention has a structure in which the conventional light guide is divided into a light guide portion and a condensing portion, so that the cross-sectional area of the light guide portion is narrowed and the light propagates inside the light guide portion. The density of the scattered light can be improved. In addition, the light condensing unit may have only a function of condensing the scattered light emitted from the light guide unit on the document reading surface. Therefore, the size and shape of the light collecting section can be set in consideration of only the light collecting efficiency, and the light collecting efficiency can be improved.

It is preferable that the light condensing portion has a reflection curved surface (elliptical surface) that reflects light emitted from the light exit surface of the light guide portion and condenses the light on the reading surface of the document. By providing a reflection curved surface (elliptical surface), the scattered light emitted from the light guide can be efficiently collected on the document reading surface.

Further, the light guide section and the condensing section may be configured to be covered with a light guide case except for the exit surface of the document illumination light. By covering the light guide portion and the light collecting portion with the light guide case, light leaked to the outside can be reflected by the light guide case and returned to the light guide portion and the light collecting portion. Thereby, the loss of the scattered light can be reduced, and the light intensity of the document illumination light can be improved.

The light source may be provided only at one end of the light guide. In this case, the reflection means is provided at the other end, or the density of the light scattering pattern formed along the longitudinal direction of the light guide portion when the reflection means is not provided,
It is increased toward the other end of the light guide.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a first embodiment of the line illumination device according to the present invention, FIG. 2 is a cross-sectional view of a contact type image sensor provided with the line illumination device shown in FIG. 1, and FIG. 4 is a graph of light intensity characteristics of document illumination light in a contact image sensor.

As shown in FIG. 1, the line illuminating device 10 according to the present invention divides the conventional light guide shown in FIG. 14 into two parts (light guide) substantially parallel to the short axis of the ellipse. (The light-guiding unit 11 and the light-collecting unit 1).
2 is brought into close contact. The ratio of the cross-sectional areas of the light guide 11 and the light collector 12 is approximately 1: 1. A light emitting source substrate (not shown) provided with a light emitting source such as an LED is provided on an end face in the longitudinal direction of the light guide section 11. Reference numeral 11a denotes a scattered light emitting surface of the light guide 11, reference numeral 11b denotes a surface parallel to the major axis of the ellipse of the light guide 11, reference numeral 11c denotes a reflection curved surface (elliptical surface) of the light guide 11, and reference numeral 11d denotes a surface. The plane, symbol P, is the light scattering pattern. Reference numeral 12a denotes an emission surface of the light collector 12, reference numeral 1
2b is a surface parallel to the major axis of the ellipse of the light collector 12;
Is a reflection curved surface (elliptical surface) of the light condensing section 12, and reference numeral 12d is an incident surface of scattered light.

As shown in FIG. 2, the line illuminating device 10 according to the present invention is housed in a light guide case 13 in close contact with the light guide 11 and the light collector 12 shown in FIG. . Light from a light source (not shown) provided on an end face in the longitudinal direction of the light guide section 11 enters the light guide section 11 from the end face of the light guide section 11. The incident light is propagated in the longitudinal direction of the light guide 11 (perpendicular to the plane of FIG. 1) while being totally reflected by the respective inner surfaces (11a to 11d) of the light guide 11. Then, the propagated light is scattered by the light scattering pattern P formed on the chamfered surface 11d. Light Guide 11 and Light Collector 1
The light-collecting portion 1 is not optically in contact with the light-receiving portion 2 at the boundary surface.
The scattered light mainly from the light scattering pattern P of the light guide portion 11 is incident on 2, and is reflected by the reflection curved surface (elliptical surface) and condensed on the document surface.

In FIG. 2, reference numeral 1 denotes a contact type image sensor provided with the line illumination device 10 according to the present invention.
Reference numeral 2 denotes a housing, reference numeral 3 denotes a lens array, reference numeral 4 denotes a line image sensor, reference numeral 5 denotes a sensor substrate, and reference numeral 6 denotes a cover glass.

FIG. 2 shows an example in which the line illuminating device 10 is arranged so that the reflection curved surface is on the left side in the figure.
The line illumination device 10 may be arranged so that its reflection curved surface is on the side closer to the lens array 3.

The light intensity distribution in the sub-scanning direction on the original surface of the contact type image sensor 1 provided with the line illuminating device 10 according to the present invention shown in FIG. 2 has the characteristics indicated by black circles in FIG. By dividing the conventional light guide into two parts, a light guide part 11 and a light condensing part 12, the density of the propagating light in the light guide part 11 is approximately doubled, and the intensity of the scattered light is increased. The peak of the light intensity has risen. Further, the light intensity at the position shifted from the light condensing point is small, which indicates that the light condensing efficiency is improved.

FIG. 4 shows a second embodiment of the line lighting device according to the present invention.
FIG. 5 is a cross-sectional view showing an embodiment, and FIG. 5 is a cross-sectional view of a contact image sensor provided with the line illumination device shown in FIG. FIG.
13 divides the conventional light guide shown in FIG. 13 into two parts vertically and substantially parallel to the major axis of the ellipse (divided into a light guide part 21 and a condensing part 22). The light guide part 21 and the condensing part 22 which are divided are brought into close contact with each other. A light-emitting source substrate (not shown) provided with a light-emitting source such as an LED is provided on an end face in the longitudinal direction of the light guide section 21. The light scattering pattern P is provided near the focal point of the ellipse on a plane 21b parallel to the major axis of the ellipse. Reference numeral 21a denotes an emission surface of the scattered light of the light guide unit 21, reference numeral 21b denotes a surface parallel to the major axis of the ellipse, reference numeral 21c denotes a surface parallel to the minor axis of the ellipse, reference numeral 21d denotes a chamfered surface,
Reference numeral 21e is an elliptical curved surface of the light guide 21. Symbol 22a
Is an incident surface of the light condensing section 22, reference numeral 22b is a reflection curved surface (elliptical surface), and reference numeral 22c is an emission surface of document illumination light.

In the line illumination device 10 shown in FIG. 4, the curvature of the reflection curved surface (elliptical surface) is increased (reflection curved surface (elliptical surface)).
To a shape closer to a circle) to improve the light collection efficiency. Here, the line illuminating device 10 divides the entire cross-sectional shape into a substantially vertical direction in the drawing to form a light guide 21 and a condensing portion 22. For this reason, the cross-sectional shape of each part 21 and 22 can be reduced, thereby facilitating molding.

As shown in FIG.
Is housed in the light guide case 23 in a state where the light guide 21 and the light condensing part 22 are in close contact with each other. Light from a light source (not shown) provided on an end face in the longitudinal direction of the light guide section 21 enters the light guide section 21 from the end face of the light guide section 21. The incident light is propagated in the longitudinal direction of the light guide 21 (perpendicular to the paper surface) while being totally reflected by each inner surface of the light guide 21. Then, the propagated light is scattered by the light scattering pattern P. Since the light guide portion 21 and the light condensing portion 22 are not in close optical contact with each other at the boundary surface, scattered light mainly from the light scattering pattern P of the light guide portion 21 is incident on the light condensing portion 22 and the reflection curved surface The light is reflected by the (elliptical surface) and condensed on the document surface.

FIG. 6 shows a third embodiment of the line illumination device according to the present invention.
It is sectional drawing which shows an Example. The line illuminating device 30 shown in FIG. 6 includes a light guide section 31 having a substantially half-ellipse cross section, a reflection section 32 formed by removing the light guide section 31, and a light guide section 31.
And a light guide case 33 covering the reflection part 32 and the light guide part 3
1 includes a light-emitting source LED provided on an end face in the longitudinal direction and a light-emitting source substrate (not shown) provided with the light-emitting source LED. The light guide case 33 may not be provided. The light scattering part P is provided on a plane parallel to the minor axis of the ellipse of the light guide part 31 and at the focal position of the ellipse. In addition, since the condensing part 32 has a lightened shape at a portion where the light guide part 31 is mounted, it is easy to mold.

The light from the light emitting source LED propagates through the light guide 31 and the light scattered by the light scattering pattern P
2, the light is reflected by the reflection curved surface (elliptical surface) of the light condensing section 32, is emitted from the light exit surface 32a, and is condensed on the document reading surface.

FIG. 7 shows a fourth embodiment of the line illumination device according to the present invention.
It is a figure showing an example. The line illuminating device 40A shown in FIG. 7A has a light guide section 41 provided on the chamfered surface 42d with respect to the condensing portion 42A in which the focal position of the reflection curved surface (elliptical surface) 42c is formed on the chamfered surface 42d. Are joined together. The line lighting device 40B shown in FIG.
The emission surface 41a of the light guide 41 is shifted to the focal point of the ellipse with respect to the light-collecting portion 42B formed on the tip side of the surface 42b where the focal position of the reflection curved surface (elliptical surface) 42c is parallel to the major axis of the ellipse. They are joined.

The light guide section 41 has a substantially rectangular cross section in the longitudinal direction, and has a chamfered one-sided portion formed as a scattered light exit surface 41a.
The light scattering pattern P is formed on the surface facing the emission surface 41a. A light-emitting source LED (shown by a virtual line) and a light-emitting source substrate (not shown) provided with the light-emitting source LED are provided on an end face in the longitudinal direction of the light guide section 41. Although FIG. 7 illustrates the light guide 41 having a substantially rectangular cross section,
The light guide 41 may have another shape.

Then, the line lighting devices 40A, 40B
The light-collecting units 42A and 42B and the light-guiding unit 41 are covered with a light-guiding case (not shown) except for the exit surface 42a of the light-gathering units 42A and 42B. Note that only the light guide 41 may be covered with the light guide case 43 as shown by a virtual line in the drawing.

FIG. 8 is a perspective view of another embodiment of a light guide incorporated in the line illumination device according to the present invention. In this embodiment, a light source 55 such as an LED is provided at one end of a light guide 51. A reflection means 56 is provided at the other end. Reflecting means 56
For example, aluminum tape, plating or mirror finish can be considered.

The light scattering pattern P is formed on the chamfered surface 51d formed along the longitudinal direction of the light guide section by means such as printing a white paint. This light scattering pattern P is a continuous pattern in the middle part in the longitudinal direction, and the light source 5
5 and the vicinity of the reflection means 56 are discontinuous patterns. The reason why the pattern at the middle portion is made darker and the pattern at both end portions is made thinner is to make the light amount near the light source 55 and the reflection means 56 larger than that at the middle portion, thereby achieving uniformity.

FIG. 9 is a graph showing the relationship between the distance from the light source and the intensity when the light guide shown in FIG. 8 and the light guide without the reflection means are used. When the light source is provided and the reflecting means is not used at the other end, the light intensity is significantly reduced at the other end. Conversely, by providing the reflecting means, the reduction in the light intensity can be suppressed considerably.

FIG. 10 is a perspective view of a further embodiment of the light guide section. In this embodiment, a light source 55 is provided at one end, but no reflecting means is provided at the other end. Instead, in this embodiment, the density of the light scattering pattern P is increased toward the other end of the light guide.

With such a configuration, the light incident from the light source into the light guide 51 is almost reflected by the light scattering pattern P before reaching the other end, and is reflected at the other end to be reflected in the light guide. Is very small, so that the amount of reflected light along the longitudinal direction of the light guide is uniform.

[0039]

As described above, the line illuminating apparatus according to the present invention comprises: a light guide section for guiding light from a light source in a longitudinal direction (main scanning direction) and generating scattered light by a light scattering pattern; The light condensing part for condensing the scattered light emitted from the light guiding part on the document reading surface is formed independently, and the light guiding part and the light condensing part are arranged in close contact or close to each other. By reducing the cross-sectional area of the light part, the density of the light propagating inside the light guide part can be improved, whereby the intensity of the scattered light can be improved without increasing the pattern width of the light scattering pattern. In addition, since the condensing section only needs to have a function of condensing the scattered light emitted from the light guide section on the document reading surface, the size and shape of the condensing section are set in consideration of only the condensing efficiency. And light collection efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a line lighting device according to the present invention.

FIG. 2 is a cross-sectional view of a contact image sensor having the line illumination device shown in FIG.

3 is a graph showing light intensity characteristics of the line illumination device shown in FIG. 1 and light intensity characteristics of a conventional line illumination device.

FIG. 4 is a sectional view showing a second embodiment of the line illumination device according to the present invention.

FIG. 5 is a cross-sectional view of a contact image sensor having the line illumination device shown in FIG. 4;

FIG. 6 is a sectional view showing a third embodiment of the line illumination device according to the present invention.

FIG. 7 is a sectional view showing a fourth embodiment of the line lighting device according to the present invention;

FIG. 8 is a perspective view of another embodiment of the light guide unit incorporated in the line illumination device according to the present invention.

9 is a graph showing the relationship between the distance from the light source and the intensity when the light guide shown in FIG. 8 is used.

FIG. 10 is a perspective view of a further embodiment of the light guide unit incorporated in the line illumination device according to the present invention.

FIG. 11 is a cross-sectional view of a contact image sensor having a conventional line illumination device.

FIG. 12 is a diagram showing an example of a cross-sectional shape of a conventional light guide.

FIG. 13 is a perspective view showing a specific example of a light scattering pattern.

FIG. 14 is a perspective view showing another specific example of the light scattering pattern.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Contact image sensor (image reading device), 2 ... Housing, 3 ... Lens array, 4 ... Line image sensor (photoelectric conversion element), 5 ... Sensor board, 6 ... Cover glass, 1
0, 20, 30, 40A, 40B ... line lighting device, 1
1,21,31,41,51 ... light guide part, 12,22,3
2, 42A, 42B: condensing portion, 11a, 21a: scattered light emission surface, 12a, 22c, 32a: original illumination light emission surface, 12c, 22c, 42c: reflection curved surface (elliptical surface), 1
3, 23, 33, 43: light guide case, 55: light source, 5
6: reflection means, P: light scattering pattern.

Claims (6)

[Claims] 1. A light source, which is incident from an end face, is guided in a longitudinal direction, and is scattered by a light scattering pattern formed along the longitudinal direction. The scattered light is formed along the longitudinal direction. A light guide portion for emitting light from the light exit surface, and a light condensing portion for condensing light emitted from the light exit surface of the light guide portion on the reading surface of the original, in close or close proximity to each other. Lighting equipment. 2. The line illuminating device according to claim 1, wherein the light condensing portion has a reflection curved surface that reflects light emitted from an emission surface of the light guide portion and condenses the light on a reading surface of a document. A line lighting device characterized by the above. 3. The line illumination device according to claim 2, wherein the reflection curved surface is an elliptical surface. 4. The line illuminating device according to claim 1, wherein the light guide unit and the light converging unit are covered with a light guide case except for a document illumination light emission surface. A line illuminator characterized by the fact that: 5. The line lighting device according to claim 1, wherein a light source is provided at one end of the light guide, and a reflecting means is provided at the other end. . 6. The line illuminating device according to claim 1, wherein a light source is provided at one end of the light guide, and a light scattering pattern formed along a longitudinal direction of the light guide. Wherein the density of the light increases toward the other end of the light guide.