JP2007036939A - Illumination unit for image reader and image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination unit for an image reader with which a reflection sheet covering a light source and a light transmission plate is accurately positioned with respect to the light source. <P>SOLUTION: An illumination unit for an image reader comprises: a light transmission plate which is formed in a transparent plate shape and has projections on both sides in a direction of thickness; a light source installed along with the outer circumference side of the light transmission plate; and a reflection sheet which includes fitting holes to be fitted with the projections, covers the light source and at least both the sides of the light transmission plate at the outer circumference side where the light source is installed, in the state of fitting the fitting holes with the projections, reflects light irradiated from the light source on an inner surface thereof covering the light source and the light transmission plate, and comprises a window part through which the reflected light passes and an original placed on an original platen is irradiated with the reflected light on one of both the sides of the light transmission plate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination unit for an image reading apparatus and an image reading apparatus using the illumination unit.

  Conventionally, as disclosed in Patent Document 1, for example, an image reading apparatus that irradiates light on a transparent original such as a photographic film placed on an original table and acquires image data of the original with an optical sensor is known. In such an image reading apparatus, for example, a so-called surface light source that uniformly irradiates light on one or more frames of a photographic film is required. In order to irradiate light uniformly in the surface spreading direction of the document, as described in Patent Document 1, it is important to position the light source and a member that directs the light emitted from the light source toward the document.

JP 2001-36691 A

  An object of the present invention is to provide an illumination unit for an image reading apparatus that accurately positions a reflection sheet that covers a light source and a light guide plate with respect to a light source, and an image reading apparatus using the illumination unit.

  (1) An illumination unit for an image reading device for achieving the above object is installed along a light guide plate which is formed in a transparent plate shape and has protrusions on both sides in the plate thickness direction, and the outer peripheral side of the light guide plate. The light guide plate on the outer peripheral edge side having a light source and a fitting hole that fits into the protrusion, and the light source and at least the light source are installed in the state where the fitting hole is fitted in the protrusion. A window portion that reflects the light emitted from the light source on the inner surface that covers the light source and the light guide plate, and passes the reflected light to irradiate the document placed on the document table. And a reflection sheet provided on one side of the both surfaces of the light guide plate.

  By fitting the fitting holes of the reflection sheet into the protrusions provided on both surfaces of the light guide plate, the position of the reflection sheet covering the light guide plate with respect to the light guide plate is accurately positioned. As a result, since the reflection sheet can be accurately positioned with respect to the light source installed along the outer peripheral side of the light guide plate, the distance between the reflection sheet covering the light source and the light source, and the angle of the reflection sheet with respect to the light source are set to a predetermined value. The reflective sheet covers the light source at intervals and angles. Thereby, the light emitted from the light source is reflected in a predetermined direction by the reflection sheet, and spreads uniformly from the window portion where the reflection sheet does not cover the light guide plate toward the document.

(2) The light guide plate may be formed in a square shape, and the protrusions may be provided on both sides of the both surfaces in the longitudinal direction.
Protrusions are provided on both sides of the light guide plate at both ends in the longitudinal direction, and the reflection sheets are positioned with respect to the light guide plate and the light source by these projections. Can be positioned.

(3) The interval between the protrusions may be different on the both surfaces of the light guide plate.
Thus, since the space | interval of the processus | protrusion provided in a light-guide plate is different on both surfaces of a light-guide plate, the front and back of a light-guide plate can be recognized and a reflection sheet can be assembled | attached to a light-guide plate.

(4) The illumination unit for an image reading device may further include a light diffusion sheet that covers the window portion and has a hole that fits into the protrusion and a notch that is positioned in the protrusion.
By covering the window portion with the light diffusion sheet, the light of the light source reflected by the reflection sheet can be diffused more uniformly. In addition, the notch of the light diffusion sheet can be positioned with the other of the protrusions while the light diffusion sheet is stretched with the holes fitted in one of the protrusions provided at both ends in the longitudinal direction, so that the light diffusion sheet is wrinkled. The window portion can be covered with the light diffusion sheet without causing it.

(5) The notch may be formed by notching a corner of the light diffusion sheet.
Notches provided at the corners of the light diffusion sheet by rotating the light diffusion sheet around the fitting position while stretching the light diffusion sheet with the holes fitted in one of the protrusions provided at both ends in the longitudinal direction Can be positioned by the other of the protrusions, so that the window portion can be easily covered with the light diffusion sheet without causing wrinkles on the light diffusion sheet.

(6) The protrusion may be provided in the vicinity of the outer peripheral edge of the light guide plate on which the light source is installed.
Since the fitting hole of the reflection sheet is fitted to the protrusion provided in the light guide plate at a location close to the light source, the distance between the light source and the reflection sheet and the angle of the reflection sheet with respect to the light source can be accurately positioned.

(7) An image reading apparatus for achieving the above object illuminates a transparent original, and the illumination unit according to any one of claims 1 to 6 and light transmitted from the illumination unit and transmitted through the transparent original. An image sensor that photoelectrically converts the image data and outputs image data.
Since the image reading device reads the transparent original with the light uniformly irradiated from the illumination unit, the image reading device can output image data having no unevenness in luminance.

  Embodiments of the present invention will be described below. FIG. 3 is a perspective view showing the image scanner 10 which is assembled with a printer, a copier, etc. (not shown) to constitute a so-called multifunction machine. 3A shows a state where the document cover 20 is opened, and FIG. 3B shows a state where the document cover 20 is closed. 3A, the original mat that covers the original platen 12 side of the original cover 20 is removed when the reflected original is read. In FIG. 3B, the cover that covers the outer side of the original cover 20 is removed. It is. The image scanner 10 may be a single scanner instead of a part of the multifunction machine. The image scanner 10 is a flat bed type including a document table 12 made of a transparent glass plate, and is an image reading apparatus including a contact type image sensor.

The document table 12 is formed of a transparent plate such as a glass plate, and a transparent document and a reflective document are placed on the plate surface. The transparent original is a developed photographic film such as a strip film or a mount film. The transparent document may be placed on the document table 12 while being held by a holder (not shown), or may be placed on the document table 12 as it is.
The main carriage 14 is equipped with a reflective original illumination unit, a linear image sensor, an image sensor 16 for reading a transparent original, and the like. The main carriage 14 is in close contact with the document table 12 by being pressed by a spring. The photoelectric conversion elements of the linear image sensor are arranged in a direction that coincides with the main scanning direction. The main carriage 14 is driven by a motor or the like and moves in the sub-scanning direction along the guide rod 18.

  An illumination unit 30 for a transparent document is attached to the document cover 20. In the image scanner 10 of the present embodiment, an illumination unit 30 is used as an illumination unit that irradiates light to a transparent original such as a photographic film and causes the image sensor 16 to read the transparent original. In addition, the illumination unit 30 may be used as an illumination unit for checking a transparent document by irradiating a transparent document placed on the document table 12 from below the document table 12.

Light from the illumination unit 30 is emitted toward the document table 12 from a rectangular opening 22 formed on the document table 12 side of the document cover 20. The document table 12 side of the illumination unit 30 is covered with a transparent protective sheet 90. The illumination unit 30 is attached to the document cover 20 on the side opposite to the document table 12.
2 is a perspective view showing the illumination unit 30, FIG. 1A is a cross-sectional view taken along the line I-I in FIG. 2, and FIG. 1B is an enlarged view of the B line portion of FIG. is there. A lamp 40 (see FIG. 4) as a light source is a rod-shaped mercury lamp, and a cable 42 is connected to both ends. The lamp 40 is installed along the side of the outer peripheral edge 52 of the long side of the rectangular light guide plate 50. The reflection sheet 60 covers the surface 55 of the light guide plate 50 on the side opposite to the document table 12, and covers the periphery of the surface 54 of the light guide plate 50 on the document table 12 side and the lamp 40. The lamp 40 is covered with the reflection sheet 60 with O-rings fitted to both ends. As shown in FIG. 1B, the two light diffusion sheets 80 cover the surface 54 of the light guide plate 50 that is not covered with the reflection sheet 60 on the side of the document table 12. The transparent protective sheet 90 covers the outside of the light diffusion sheet 80.

Next, the structure of the light guide plate 50, the reflection sheet 60, and the light diffusion sheet 80 will be described in detail.
4 shows the lamp 40, the light guide plate 50, and the reflection sheet 60 before assembly, FIG. 5 shows both surfaces 54 and 55 in the thickness direction of the light guide plate 50, and FIG. 6 shows an enlarged view of the reflection sheet 60. ing.
The light guide plate 50 is formed in a transparent rectangular plate shape. On the surface 54 of the light guide plate 50 on the side of the document table 12, fine unevenness is formed so that light irradiated from the inside of the light guide plate 50 to the outside diffuses. A pair of projections 56 and 57 are provided on both sides 54 and 55 in the thickness direction of the light guide plate 50 on both ends in the longitudinal direction near the outer peripheral edge 52 on the side where the lamp 40 is installed. The distance L1 between the protrusions 56 and the distance L2 between the protrusions 57 are different in length. This is because the front and back of the light guide plate 50 are not mistaken when the reflection sheet 60 is assembled to the light guide plate 50.

  The inner surface 61 of the reflection sheet 60 that covers the lamp 40 and the light guide plate 50 is subjected to processing such as coating for reflecting light. Two fold line processes 62 are applied to portions of the reflection sheet 60 that cover the lamp 40. The reflection sheet 60 covers the lamp 40 by being bent along the folding line process 62 (see FIG. 1). Fitting holes 64, 66, 68 that fit with the protrusions 56, 57 formed on the light guide plate 50 are formed in the vicinity of the folding line processing 62. The fitting holes 64 and 66 are formed on one end side in the longitudinal direction. The fitting hole 68 is a long hole and is formed on the other end side in the longitudinal direction. The peripheral portions 70, 74, and 76 of the reflection sheet 60 are bent to the surface 54 of the light guide plate 50 on the side of the document table 12. A notch 72 is formed in a corner portion of the peripheral portion 70 on the fitting hole 68 side. When the reflection sheet 60 is assembled to the light guide plate 50, the fitting holes 64 and 66 on one end side in the longitudinal direction of the reflection sheet 60 are fitted into the protrusions 56 and 57 on one end side in the longitudinal direction of the light guide plate 50. The fitting hole 68 on the other end side in the longitudinal direction of the reflection sheet 60 is fitted into the projection 57 on the other end side in the longitudinal direction of the light guide plate 50, and the other in the longitudinal direction of the reflection sheet 60. The notch 72 on the end side is aligned with the protrusion 56 on the other end side in the longitudinal direction of the light guide plate 50. By aligning the reflective sheet 60 with respect to the light guide plate 50 in this way, a shift when the reflective sheet 60 is assembled to the light guide plate 50 is prevented. Further, the projections 56 and 57 for positioning the fitting holes 64, 66 and 68 and the notch 72 of the reflection sheet 60 are in the vicinity of the outer peripheral edge 52 of the light guide plate 50 on the side where the lamp 40 is installed and at both ends in the longitudinal direction. On the side.

  Therefore, in a state where the reflection sheet 60 is bent by the fold line processing 62, the interval between the lamp 40 and the reflection sheet 60 and the angle of the reflection sheet 60 with respect to the lamp 40 become a predetermined interval and angle over the longitudinal direction. Thereby, since the light irradiated from the lamp | ramp 40 is reflected in the predetermined direction by the inner surface 61 of the reflective sheet 60, it can prevent that light is reflected in the direction which biased.

  In addition, the other side in the longitudinal direction of the reflection sheet 60 is positioned with respect to the protrusions 56 and 57 by an elongated fitting hole 68 and a notch 72. Therefore, the processing errors in the longitudinal direction of the fitting holes 68 and the notches 72 with respect to the fitting holes 64 and 66, or the projections 56 and 57 on one side in the longitudinal direction on the light guide plate 50, on the other side in the longitudinal direction. Even if a processing error in the longitudinal direction of the protrusions 56 and 57 occurs, the processing error can be absorbed by the fitting hole 68 and the notch 72.

FIG. 7 shows a state where the lamp 40 and the light guide plate 50 are covered with the reflection sheet 60. A window portion 58 that is not covered with the reflection sheet 60 is provided on the side of the light guide plate 50 on the document table 12 side. The light of the lamp 40 reflected by the reflection sheet 60 is emitted from the window portion 58 toward the document.
FIG. 8 shows an assembling process of the light diffusing sheet 80. The light diffusion sheet 80 is a transparent sheet. Due to the fine irregularities formed on the surface of the light diffusion sheet 80, the light passing through the light diffusion sheet 80 is uniformly diffused. A fitting hole 82 that fits into the projection 56 of the light guide plate 50 is formed in a corner portion on one end side in the longitudinal direction of the light diffusion sheet 80, and a notch 84 is formed in a corner portion on the other end side. ing. The cutout formed in the light diffusion sheet 80 may be formed by cutting out a part of the other end side instead of the corner portion of the light diffusion sheet 80.

  Then, while stretching the light diffusion sheet 80 with the fitting hole 82 lightly fitted to the protrusion 56, the notch 84 is applied to the protrusion 56 to position the light diffusion sheet 80 with respect to the light guide plate 50, and light diffusion is performed. The window portion 58 is covered with the sheet 80. Similarly, the second light diffusion sheet 80 is attached on the first light diffusion sheet 80. Further, similarly, the protective sheet 90 is pasted on the second light diffusion sheet 80. Thus, it is possible to prevent the light diffusion sheet and the protective sheet 90 from wrinkling by attaching the light diffusion sheet 80 and the protective sheet 90 to each other.

(Other embodiments)
In the above embodiment, the protrusions 56 and 57 are provided in the vicinity of the outer peripheral edge 52 of the light guide plate 50 on the side where the lamp 40 is installed. However, if the protrusions are provided on both surfaces of the light guide plate 50, the position is particularly It is not limited. For example, the protrusions 56 and 57 may be provided in the vicinity of the outer peripheral edge of the light guide plate 50 on the side opposite to the lamp 40.
In the above embodiment, the lamp 40 is installed along the long side of one side of the rectangular light guide plate 50, but the lamp may be installed along a plurality of sides of the light guide plate 50. Further, the shape of the light guide plate is not limited to a rectangular shape such as a rectangle, and may be another polygonal shape.

(A) is the II sectional view taken on the line of FIG. 2, (B) is an enlarged view of the B line part of (A). The perspective view which shows the illumination unit which concerns on this embodiment. 1 is a perspective view illustrating an image scanner according to an embodiment. Explanatory drawing which shows the illumination unit before the assembly | attachment of this embodiment. Explanatory drawing which shows the front and back of the light-guide plate of this embodiment. The enlarged view which shows the reflective sheet of this embodiment. Explanatory drawing which shows the front and back of the illumination unit which assembled | attached the reflective sheet of this embodiment. Explanatory drawing which shows the assembly | attachment process of the light-diffusion sheet of this embodiment.

Explanation of symbols

10: image scanner (image reading device), 12: document table, 14: main carriage, 20: document cover, 30: illumination unit, 40: lamp (light source), 50: light guide plate, 52: outer peripheral edge, 56, 57 : Projection, 60: reflection sheet, 64, 66, 68: fitting hole, 72: notch, 80: light diffusion sheet, 82: fitting hole, 84: notch

Claims (7)

A light guide plate formed in a transparent plate shape and having protrusions on both sides in the plate thickness direction;
A light source installed along an outer peripheral side of the light guide plate;
Covering both surfaces of the light guide plate on the outer peripheral side where the light source and at least the light source are installed with the fitting hole fitted into the projection, and the fitting hole fitted into the projection, Reflecting the light emitted from the light source on the inner surface covering the light source and the light guide plate, and passing through the reflected light to irradiate the document placed on the document table with both windows of the light guide plate A reflective sheet provided on one side of the
An illumination unit for an image reading apparatus.   The illumination unit for an image reading device according to claim 1, wherein the light guide plate is formed in a quadrangular shape, and the protrusions are provided on both sides of the both surfaces in the longitudinal direction.   The illumination unit for an image reading device according to claim 2, wherein an interval between the protrusions is different on the both surfaces of the light guide plate.   The light diffusion sheet which further covers the said window part and has a fitting hole fitted to the said protrusion of the one end side of a longitudinal direction, and the notch positioned by the said protrusion of the other end side of a longitudinal direction is provided. Or an illumination unit for an image reading apparatus according to 3;   The illumination unit for an image reading device according to claim 4, wherein the notch is formed by notching a corner of the light diffusion sheet.   The illumination unit for an image reading device according to claim 1, wherein the protrusion is provided in the vicinity of the outer peripheral edge of the light guide plate on which the light source is installed. The illumination unit according to any one of claims 1 to 6, which illuminates a transparent original;
An image sensor that photoelectrically converts light emitted from the illumination unit and transmitted through the transparent original, and outputs image data;
An image reading apparatus comprising:

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