JP2003348299A - Line illuminator and reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line illuminator capable of uniformizing illumination light emitted from the neighborhood of the light source of a bar-like light guide. <P>SOLUTION: Since a lower side surface 12 has the largest area among the respective side surfaces of the light guide 1 and faces an emitting surface 17, the surface 12 is a side surface which reflects the largest light quantity to the emitting surface 17. Then, a light scattering pattern is not provided at a place in the neighborhood of the light source 2 in this surface 12, but a light scattering pattern 18b is provided at a place separated from the light source of the same surface 12. Then, when the light scattering pattern is not provided at a place in the neighborhood of the light source 2, a reflected light quantity from the place in the neighborhood of the light source 2 is short and that from the surface 17 becomes unequal along the longitudinal direction of the light guide 1. Then, a light scattering pattern 18a for compensating the shortage of the reflected light quantity is provided on a left side surface 13. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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.

In a conventional line lighting device, a light source is arranged at one end of a light guide, and light from the light source is introduced into the light guide.
The light is emitted from the emission surface while being repeatedly reflected in the light guide, the emitted light (illumination light) is made to enter the reading surface of the original through the cover glass, and the reflected light is detected by the line image sensor via the lens array. Thus, the original is read.

In the light guide, a light scattering pattern for generating scattered light and making the intensity of emitted light uniform is formed on a side surface on which the amount of reflected light is largest. Many proposals have been made for the light scattering pattern. In general, the pattern near the light source is small, and the pattern becomes large as the distance from the light source increases. Further, Japanese Patent No. 2693098 proposes a pattern in which a normal passing through the center of the pattern deviates from a normal passing through the center of the light source in the vicinity of the light source among the above patterns.

[0005]

In each of the above-mentioned prior arts, the light scattering pattern is formed on the side surface facing the light exit surface, that is, the side surface on which the amount of reflected light is the largest. Since this surface is the side surface having the largest area in the case of a flat rectangular rod-shaped light guide, it is easy to form a light scattering pattern by printing,
Further, since it is necessary to form a light scattering pattern having a large area at a location far from the light source, the light scattering pattern is formed on the side surface.

However, at a location near the light source, the change in the amount of reflected light with respect to the change in the area of the light scattering pattern becomes too large, and the uniformity of the intensity of the emitted light cannot be obtained due to a minute change when printing the light scattering pattern. Would.

[0007]

According to a first aspect of the present invention, there is provided a line illuminating apparatus including: a light guide having a square rod shape; and a light source disposed at one end of the light guide. At the corners along the longitudinal direction of the light guide, an emission surface for emitting light incident on the light guide from the light source is formed, and the side near the light source among the side surfaces on which the amount of reflected light to the emission surface is the largest. A light scattering pattern is provided in a place away from the light source without providing a light scattering pattern in a given position, and at least one of the two side surfaces orthogonal to the side surface where the amount of reflected light is largest is located closer to the light source. A light scattering pattern was provided.

In the case where the light scattering pattern provided near the light source on the side surface is near the light source, the normal passing through the center of the light scattering pattern and the normal passing through the center of the light source may be matched. preferable.

Further, a line lighting device according to a second aspect of the present invention comprises:
A light guide having a square rod shape, and a light source disposed at one end of the light guide, and light incident on the light guide from the light source is emitted to a corner along the longitudinal direction of the light guide. A light scattering pattern is provided at a position away from the light source without providing a light scattering pattern at a position near the light source among the side surfaces on which the amount of reflected light to the light emitting surface is the largest while forming the light emitting surface. A light scattering pattern was provided at a position close to the light source on the side surface opposite to the side surface where the amount of light is largest and coincident with the normal passing through the center of the light source.

According to the first and second aspects of the present invention, a light scattering pattern is not provided at a portion near the light source, that is, a portion most sensitive to reflection, among the side surfaces where the amount of reflected light to the emission surface is the largest. Since the light scattering pattern is formed on the other side surface, even if the area of the light scattering pattern changes, the sensitivity of the increase or decrease of the amount of reflected light to this change can be reduced,
Fine adjustment becomes easy.

Further, according to the present invention, in a portion near the light source, the ratio of the light reflected from the light scattering pattern directly emitted from the emission surface is extremely small. The emission also eliminates the need to bother to deviate the normal passing through the center of the light scattering pattern from the normal passing through the center of the light source.

The light source is not limited to white light.
An LED light source in which (red), G (green) and B (blue) chips are arranged in a straight line is included, and the present invention also includes a reading device such as an image sensor incorporating the above-described line illumination device. .

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing a first embodiment of a line lighting device according to the present invention, FIG. 2 (a) is an end view of the line lighting device shown in FIG. 1, and FIG. 1 (b) is an end view showing a modification. The line illumination device includes a light guide 1 and a light source 2, which are housed in a case 20.

The light guide 1 is formed by molding glass or transparent resin into a flat rectangular bar shape. That is, when viewed from the light source 2, the light guide 1 includes an upper side surface 11, a lower side surface 12, a left side surface 13, and a right side surface 1.
4, an output surface 17 formed between the end surfaces 15 and 16 and the upper surface 11 and the right side surface 14 for a total of seven surfaces. The light source 2 has R (red), G (green), and B (blue) LED chips 2a arranged in a horizontal line.

Since the lower side surface 12 of each side surface of the light guide 1 has the largest area and faces the emission surface 17, it is the side surface on which the amount of light reflected on the emission surface 17 is the largest. A light scattering pattern is not provided in a portion of the lower surface 12 near the light source 2, and a light scattering pattern 18 b is provided in a portion of the same lower surface 12 distant from the light source 2. The light scattering pattern 18b is formed by printing a white paint, for example.

If the light scattering pattern is not provided in the vicinity of the light source 2 as described above, the amount of light reflected from the vicinity of the light source 2 will be insufficient, and the amount of light emitted from the emission surface 17 will be reduced. It becomes non-uniform along the longitudinal direction. Therefore, in the first embodiment, a light scattering pattern 18a is provided on the left side surface 13 to compensate for the above-mentioned shortage of the amount of reflected light. Since the sensitivity of the left side surface 13 is lower than that of the lower side surface 12, the light scattering pattern 18
The area of a can be increased, and fine adjustment is easy.

In this embodiment, the light scattering pattern 1
The normal passing through the center of 8a and the normal passing through the center of the light source 2 are matched. In the present invention, the normal line coincides with a normal line passing through the center of the light scattering pattern 18a and a normal line passing through the center of the light source 2 in a horizontal plane parallel to the upper side surface 11 or the lower side surface 12, or the left side surface 13 or It is in a vertical plane parallel to the right side surface 14.

Since the left side surface 13 and the right side surface 14 are parallel, the light scattering pattern 1 formed on the left side surface 13 is formed.
Part of the light scattered at 8a is incident on the right side surface 14 at a substantially right angle as shown in FIG. 2A, and is transmitted without being reflected on the right side surface 14. This slightly leads to a loss of light quantity. Therefore, as shown in FIG. 2B, a part or all of the right side surface 14 is chamfered 19 and the left side surface 13 is chamfered.
May be reflected.

FIG. 3 is a perspective view showing a modification of the first embodiment. In this embodiment, a left side surface 13 and a right side surface 14 are shown.
Light scattering patterns 18a are formed on both side surfaces of
No light scattering pattern is provided in a portion near the light source 2 among them. In the case of this embodiment as well, it becomes easy to control the amount of emitted light in the vicinity of the light source, as in the previous embodiment. Also in this embodiment, the normal passing through the center of the light scattering pattern 18a and the normal passing through the center of the light source 2 are matched.

FIG. 4 shows a second embodiment of the line illumination device according to the present invention.
FIG. 5 is a perspective view showing the embodiment, and FIG. 5 is a view taken in the direction of arrow A in FIG.
(Red), G (green), and B (blue) chips are arranged in a straight line in the vertical direction, and a light scattering pattern 18a is formed on the upper side surface 11 in a portion closer to the light source 2 so that the light source 2
A light scattering pattern 18b whose area is gradually increased is formed on the lower side surface 12 in a portion away from the light source.

In the second embodiment, the light scattered by the light scattering pattern 18a on the upper side surface 11 does not directly exit from the exit surface, but exits after being reflected by another surface. The normal passing through the center of the scattering pattern 18a is matched with the normal passing through the center of the light source 2.

FIG. 6 is a sectional view of a contact type image sensor provided with a line illuminating device according to the present invention. The line illuminating device is housed in a case 20 and light from a light source is transmitted through the light guide 1.
Light enters the light guide 1 from the end face of the light guide 1, and the incident light propagates in the longitudinal direction of the light guide 1 while being totally reflected by the inner surface of each side surface of the light guide 1. The propagating light is scattered by the light scattering pattern 18 and emitted from the emission surface 17 toward the document surface 21. Light reflected from the document surface 21 is received by a line image sensor 23 via a lens array 22.

[0023]

As described above, the line illuminating device according to the present invention has a configuration in which, out of the side surfaces of the rectangular rod-shaped light guide, the side surface on which the amount of light reflected on the light exit surface is the largest is located only at a position away from the light source. A light scattering pattern is formed, and no light scattering pattern is formed in the vicinity of the light source. Instead, a light reflection pattern is formed on the side surface, which has relatively low sensitivity to the light source and hardly emits reflected light directly from the emission surface. As a result, the amount of reflected light can be easily made uniform at a portion near the light source. In particular, when the light reflection pattern is formed by printing, a relatively large area is sufficient, so that control is simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a line illumination device according to the present invention.

2A is an end view of the line illumination device shown in FIG. 1, and FIG. 2B is an end view showing a modification.

FIG. 3 is a perspective view showing another modification of the first embodiment.

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

FIG. 5 is a view in the direction of arrow A in FIG. 4;

FIG. 6 is a cross-sectional view of a contact type image sensor provided with a line illumination device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light guide, 2 ... Light source, 2a ... LED chip, 11 ... Upper side, 12 ... Lower side, 13 ... Left side, 14 ... Right side, 1
5, 16 end surface, 17 emission surface, 18a, 18b light reflection pattern, 19 chamfer, 20 case, 21 document surface, 22 lens array, 23 line image sensor.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Takashi Kishimoto             7-28 Kitahama, Chuo-ku, Osaka-shi, Osaka             Nippon Sheet Glass Co., Ltd. (72) Inventor Kozo Fujino             7-28 Kitahama, Chuo-ku, Osaka-shi, Osaka             Nippon Sheet Glass Co., Ltd. (72) Inventor Masafumi Taguchi             7-28 Kitahama, Chuo-ku, Osaka-shi, Osaka             Nippon Sheet Glass Co., Ltd. F-term (reference) 2H108 AA01 CA01 CB01                 2H109 AA02 AA13 AA26                 5C051 AA01 BA04 DA03 DB21 DB29                       DB31 DC04 DC05 DC07 EA01                       FA01                 5C072 AA01 CA05 CA07 CA09 CA15                       DA16 DA21 DA25 DA30 EA07                       QA11 XA01

Claims (5)

[Claims] 1. A light guide having a square rod shape, and a light source disposed at one end of the light guide. A light source enters a light guide from a light source at a corner of the light guide along a longitudinal direction. In the line lighting device in which the emission surface for emitting the emitted light is formed, a portion near the light source among the side surfaces on which the amount of reflected light to the emission surface is the largest is provided with no light scattering pattern and is located at a location away from the light source. A line illuminating device provided with a light scattering pattern, and a light scattering pattern provided at a position near a light source on at least one of two side surfaces orthogonal to the side surface on which the amount of reflected light is largest. . 2. The line illuminating device according to claim 1, wherein a normal passing through a center of a light scattering pattern provided at a position near a light source on at least one of the two side surfaces and a center of the light source. A line illuminating device characterized in that a passing normal line coincides. 3. A light guide having a square rod shape, and a light source disposed at one end of the light guide. A light source enters the light guide at a corner along the longitudinal direction of the light guide. In the line lighting device in which the emission surface for emitting the emitted light is formed, a portion near the light source among the side surfaces on which the amount of reflected light to the emission surface is the largest is provided with no light scattering pattern and is located at a location away from the light source. A line provided with a light scattering pattern, wherein the light scattering pattern is provided at a position which is close to the light source on the side surface opposite to the side surface where the amount of reflected light is largest and coincides with a normal passing through the center of the light source. Lighting equipment. 4. The line lighting device according to claim 1, wherein the light sources are R (red), G (green), and B (green).
A line lighting device, wherein each of the (blue) chips is an LED light source arranged in a straight line. 5. A reading device incorporating the line illumination device according to claim 1.