JP2010193361A - Led light source and image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED light source which is suitable as a light source of an image reader. <P>SOLUTION: The light source is used for the image reader comprising: a platen on which a read document is placed; an LED light source for lighting up the read document placed on the platen; a condenser lens for converging reflected light from a main scanning line on the read document lit up by the LED light source; and a light-receiving means for receiving the reflected light from the main scanning line on the read document which has been converged by the condenser lens. The light source comprises an LED as a light-emitting source and a light guide for diffusing a lighting region of the LED lighting up the read document placed on the platen to at least a main scanning line width of the read document, and includes a plurality of reflecting surface bodies which are arrayed at predetermined intervals in the main scanning line direction while surface-confronted with the LED side in an internal surface reflection optical path of the light guide, and reflect the light of the LED to outside the light guide along the main scanning lines. A length of each reflecting surface body in a direction orthogonal to the main scanning line direction is suitably adjusted according to the quantity of light to be reflected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an LED light source using an LED used as a light source of an image reading apparatus as a light source, and an optical reduction type image reading apparatus using the LED light source as a light source.

Conventionally, this type of optical reduction type image reading apparatus is known, for example, from Patent Document 1. As shown in FIG. 1A, the optical reduction type image reading apparatus includes a platen P on which a reading document S is placed, and a reading document S placed on a surface on which the reading document S is placed. A first carriage body including a light source LA that illuminates the original surface and a reflection plate M1 that reflects light reflected from the original surface of the read original S, and a reflection for guiding the reflected light from the reflection plate M1 to the light receiving means CCD. A second carriage body composed of a plate M2 and a reflection plate M3; and as shown in FIG. 5B, the reflected light from the reflection plate M3 of the second carriage body is condensed and imaged on the light receiving surface of the light receiving means CCD. And a light receiving unit including a light receiving unit CCD that receives the image light of the read document S collected by the optical lens LE.

Then, the image reading apparatus moves the first carriage body from the left corner to the right corner at the speed V along the original surface of the read original S as shown in FIG. Following the movement of the body, the second carriage body is moved in the same direction at half the moving speed of the first carriage body, and the document surface of the read document S is read by the light receiving means CCD.

On the other hand, as a light source LA used as a light emission source of these image reading apparatuses, for example, an LED light source LA using an LED shown in Patent Document 2 as a light source is known. When the LED light source LA is shown in FIG. 5, first, as shown in FIG. 5 (b), the LED light source LA is composed of an LED serving as a light emitting source and a light guide RG for guiding the light of the LED. The light guide RG forms a reflecting surface RG1 protruding into the light guide for taking out the light emitted from the LED from the light guide in order to irradiate the original surface of the read document. . As shown in FIG. 7C, the reflecting surface body RG1 is formed in a V-shaped (or arc-shaped) depression on the surface of the light guide RG at a constant interval p.

JP 2002-101263 A JP 2000-048616 A

First, the optical reduction type image reading apparatus has the following problems.

That is, in the optical reduction type image reading apparatus, even when the original surface of the read original S is illuminated with a uniform light amount range LV1 of the illumination light LA-Lv of the light source LA as shown in FIG. The amount of light received by the light receiving means CCD through the LE is influenced by the cosine fourth law, and the light amounts LV2 and LV3 at both ends are lowered as shown in the figure. Becomes darker, resulting in unevenness in the amount of light in the image as a whole. The cosine fourth power law means that the image plane illuminance by light incident at an arbitrary angle with respect to the optical axis is 4% of the cosine of the incident angle (α) with respect to the image plane illuminance by incident light parallel to the optical axis. The law of decreasing in proportion to the power.

Therefore, in the case of the above-mentioned Patent Document 1, the problem is dealt with by interposing a slit plate SH in which a slit opening SH1 is formed between the optical lens LE and the light receiving means CCD as shown in FIG. . The slit opening SH1 of the slit plate SH is opened so that the gap at the center is narrow and becomes wider toward the sides. Then, as shown in FIG. 4, the amount of received light is reduced as it goes to the center of the light receiving means CCD to make it uniform, thereby eliminating unevenness in the amount of light in the image.

However, in the method of interposing the slit plate SH, the total light amount level is lowered by cutting the amount of light received by the light receiving means CCD, and the entire read image becomes dark, and in some cases, the reading becomes impossible due to insufficient light amount.

On the other hand, the LED light source LA has the following problems.

That is, as shown in FIG. 5A, the LED light source LA is known to have a light source characteristic LA-Lv in which the vicinity of the LED causes a peak phenomenon due to light concentration.

Therefore, in the case of the above-mentioned Patent Document 2, as shown in FIG. 6 (b), the light source LED is separated from the light guide RG, and a diaphragm plate Ep is interposed between them, so that the light from the light source LED is transmitted. While narrowing down, the surface on which the reflecting surface RG1 is formed is inclined α so that the light guide diameter decreases toward the far side of the LED, and the peak phenomenon is suppressed and the light source characteristic LA-Lv is reduced as shown by the solid line in FIG. It is made almost uniform.

However, in the method of gradually reducing the diameter of the light guide in order to make the surface on which the reflecting surface RG1 is formed to have the inclination α, the length of the light guide is limited, and it is difficult to make a light guide RG having a wide uniform light source region. . Further, when the light guide RG is made by resin molding, the light guide guide is distorted due to the flow of hot water or distortion due to the environmental temperature, etc., and the light guide is liable to cause unevenness of light quantity.

The present invention has been conceived under such circumstances, and is optimal as a light source for an image reading apparatus. In particular, when used in an optical reduction type image reading apparatus, the cosine 4 of the apparatus has. An object of the present invention is to provide an LED light source that can eliminate light intensity unevenness due to the influence of the power law on the light source side and is excellent in productivity.

In order to achieve the above object, the present invention achieves the above-described problem: a platen on which a read document is placed, an LED light source that illuminates the read document placed on the platen, and main scanning of the read document illuminated by the LED light source An image reading apparatus comprising: a condensing lens that condenses the reflected light from the line; and a light receiving unit that receives the reflected light from the main scanning line of the read original collected by the condensing lens, The LED light source includes an LED serving as a light emission source and a light guide that diffuses an illumination area of the LED that illuminates the read original placed on the platen to at least the main scanning line width of the read original. The light guides are arranged along the main scanning line with a predetermined interval in the main scanning line direction while facing the LED in the inner surface reflection light path of the guide. Comprising a plurality of reflective face piece that reflects outward, it is characterized by comprising appropriately adjusted depending on the amount of light reflecting length in the direction perpendicular to the main scanning line direction of the respective reflection face piece.

More specifically, the reflecting surface body is formed by a surface that is thinned in an inverted V-shaped cross section or an inverted saddle shape from the outside of the light guide, and each length of the reflecting surface body is at least the condensing lens. The light amount distribution in the main scanning line direction reflected from the white reference surface and received by the light receiving means is adjusted to a substantially uniform length so that the amount of light that passes through the cosine and can be interpolated with the reflected light amount can be interpolated with the reflected light amount. ing.

Further, the LED uses a single-chip type white LED composed of a blue LED chip and a YAG (yttrium, aluminum, garnet) yellow phosphor, and three or more LEDs are arranged along the main scanning line direction. They are arranged at different intervals.

In the present invention, the width of each reflecting surface formed in the light guide in the sub-scanning line direction is set according to the amount of light dimmed by the condenser lens, so that each reflecting surface corresponds to the width. The amount of reflected light is increased or decreased, the amount of light attenuated by the cosine fourth law of the condensing lens is reinforced, and the image can be read without unevenness in the amount of light.

In addition, the reflective surfaces can be arranged at regular intervals in the main scanning line direction of the read original, and the reflective surfaces do not kick the optical path by ensuring sufficient spacing between the reflective surfaces. Since the surface can reflect the light from the LED, it is possible to read an image without unevenness in the amount of light.

Furthermore, when the light guide is made by resin molding, it is not necessary to change the diameter of the light guide, and the light guide is not distorted due to distortion caused by hot water flow or ambient temperature. .

FIG. 2 is a configuration diagram illustrating an outline of a conventional optical reduction type image reading apparatus, in which FIG. 1A is a configuration diagram of the apparatus and FIG. 2B is an optical path diagram of an optical reduction system. It is a figure which shows the light quantity characteristic of the light source side of FIG. 1, and the light quantity characteristic of the light-receiving side. 2A and 2B are explanatory diagrams for explaining a correction method for correcting the light quantity characteristic on the light receiving side of FIG. 2 using a slit plate, wherein FIG. 2A is a perspective view for explaining the arrangement relationship of the slit plate, and FIG. It is a figure explaining. It is a figure which shows the light quantity characteristic by the side of a light source at the time of using the slit board of FIG. 2, and the light quantity characteristic by the side of light reception. The conventional LED light source will be described. (A) is a characteristic diagram showing the light quantity characteristics of the light source, (b) is a side view showing the configuration of the LED light source, and (c) is a configuration of the LED light source. It is a top view. It is a figure for demonstrating the method of improving the light quantity characteristic of the conventional LED light source, (a) A figure is a characteristic view which shows the light quantity characteristic by the light source, (b) A figure is a side view which shows the structure of an LED light source. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the outline | summary of the two carriage type optical reduction type image reading apparatus which is 1st Example carrying the LED light source which concerns on this invention, (a) A figure is the apparatus block diagram, (b) The figure is optical. It is a reduction system optical path diagram. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the outline | summary of the carriage integrated optical reduction type image reading apparatus which is 2nd Example which mounts the LED light source which concerns on this invention, (a) A figure is the apparatus block diagram, (b) A figure is optical. It is a reduction system optical path diagram. It is a disassembled perspective view which shows the structure of the LED light source which concerns on this invention. It is a partial exploded perspective view which shows the structure of the LED light source which concerns on this invention. It is side surface sectional drawing which shows the structure of the LED light source which concerns on this invention. It is explanatory drawing which shows the structure of the light guide of the LED light source which concerns on this invention, (a) A figure is the top view, (b) A figure is a side view. It is a figure which shows the light quantity characteristic by the side of the light source of the LED light source which concerns on this invention, and the light quantity characteristic by the side of light reception. FIG. 9 is a configuration diagram showing an outline of a contact sensor type image reading apparatus according to a third embodiment of the present invention, in which FIG. (A) is a configuration diagram of the apparatus, and FIG. FIG. It is a figure which shows the light quantity characteristic by the side of the light source of the LED light source which concerns on the 3rd Example, and the light quantity characteristic by the side of light reception. It is explanatory drawing which shows the arrangement configuration of the other LED which concerns on this invention.

Hereinafter, an embodiment in which the LED light source of the present invention is used as a light source of an optical reduction type image reading apparatus will be described in detail.

[Configuration and Operation Overview of Image Reading Apparatus]
FIG. 7 is a block diagram showing an outline of a two-carriage optical reduction type image reading apparatus as a first embodiment in which the LED light source according to the present invention is mounted. FIG. 8 shows a first embodiment in which the LED light source according to the present invention is mounted. 2A and 2B are configuration diagrams illustrating an outline of a carriage-integrated optical reduction type image reading apparatus according to a second embodiment, in which FIG. 1A is a configuration diagram of the apparatus, and FIG. 2B is an optical path diagram of an optical reduction system.

First, a two-carriage optical reduction type image reading apparatus according to an embodiment of FIG. 7 will be described. In FIG. 4A, a platen P on which the read original S is placed, an LED light source LA that illuminates the original face of the read original S placed on the placement surface of the platen P, and the original face of the read original S. A first carriage body CAR1 composed of a reflection plate M1 that reflects the reflected light of the first, and a second carriage body CAR2 composed of a reflection plate M2 and a reflection plate M3 for guiding the reflected light of the reflection plate M1 to the light receiving means CCD. As shown in FIG. 5B, the reflected light from the reflecting plate M3 of the second carriage body is collected and focused by the optical lens LE for focusing the reflected light on the light receiving surface of the light receiving means CCD. And a light receiving unit comprising a light receiving means CCD for receiving the image light of the read original S.

Then, the image reading apparatus moves the first carriage body CAR1 from the left corner to the right corner of the paper at a speed V along the original surface of the read original S, as shown in FIG. Following the movement of the carriage body CAR1, the second carriage body CAR2 is moved in the same direction at half the movement speed of the first carriage body CAR1, and the document surface of the read document S is read by the light receiving means CCD. ing.

Next, a carriage-integrated optical reduction type image reading apparatus according to the second embodiment shown in FIG. 8 will be described. In FIG. 6A, a platen P on which the read original S is placed, an LED light source LA that illuminates the original face of the read original S placed on the placement surface of the platen P, and the original face of the read original S A reflection plate M1 that reflects the reflected light of the reflection plate, a reflection plate M2 and a reflection plate M3 for guiding the reflection light of the reflection plate M1 to the light receiving means CCD, and reflection from the reflection plate M3 as shown in FIG. An optical lens LE for condensing the light and forming an image on the light receiving surface of the light receiving means CCD and a light receiving section comprising the light receiving means CCD for receiving the image light of the read original S collected by the optical lens LE are moved in one movement. The carriage body CAR3 is incorporated in the frame body.

Then, the image reading apparatus moves the carriage body CAR3 from the left corner to the right corner of the paper at a constant speed along the original surface of the read original S as shown in FIG. Reading is performed by the light receiving means CCD.

[Configuration of LED light source LA]
Next, the configuration of the LED light source according to the present invention will be described in detail with reference to FIGS. FIG. 9 is a perspective view showing an overview of the LED light source, and FIG. 10 is an exploded perspective view of the LED light source.

First, the LED light source LA includes a light guide RG, a support frame RE that supports the light guide RG, and an LED that is attached to the support frame RE and serves as a light source that illuminates the read document S via the light guide RG. It is composed of

[Description of light source LED]
The LED used as the light source is a white LED. This white LED is of a single chip type and is an InGaN blue LED and a YAG (yttrium, aluminum, garnet) yellow phosphor, and is a light source configured to emit white light with electric energy. Three white LEDs are arranged at appropriate intervals along the main scanning direction of the read document S. The number of white LEDs is appropriately increased or decreased according to the length of the light guide RG and the amount of illumination light.

[Description of Support Frame RE]
The support frame RE is a frame in which a white pigment is mixed with ABS resin [acrylonitrile, butadiene, styrene] so that the light guide RG can be supported, and at least the inner surface that supports the light guide RG has an opaque white color. The reason why the inner surface is opaque white is that the reflection angle of the light guide RG is increased by reflecting light leaking out of the light guide RG outside the critical angle and returning the leaked light into the light guide RG. I have to. In particular, the main scanning line direction end Q1 of the support frame RE that covers the curved reflecting surface RG0 of the light guide RG, which will be described later, is a critical angle position at which at least light emitted from the LED can be totally reflected in the main scanning line direction of the light guide RG. Is formed.

[Description of Light Guide RG]
The light guide RG is generally formed of a highly transparent material, for example, a transparent solid material made of polymethyl methacrylate resin PMMA, an acrylic resin known as acrylic glass, or a polycarbonate resin which is a kind of thermoplastic plastic. . The refractive index of the acrylic resin is 1.49, the critical angle (the angle at which total reflection begins to occur) is about 42 degrees, the refractive index of the polycarbonate resin is 1.585, and the critical angle is about 39 degrees.

Here, it is molded using acrylic resin. As shown in the enlarged view of FIG. 10, the lower surface is formed of a concave groove cut into a V shape from the outside into the resin, and the light passing through the resin is read. A plurality of reflecting surface bodies RG1 forming a reflecting surface that reflects in the direction of illuminating the document S are formed at a constant interval P, and the entire document width of the read document S is illuminated along the main scanning direction of the read document S. .

Further, the light guide RG will be described in detail with reference to FIG. The figure shows a substantially central cross-section along the reading main scanning direction. In particular, the reflective surface in the upper part of the LED forms a curved reflective surface RG0 along the locus drawn by the following equation.
X ² / a ² + Y ² / b ² = 1 ... ellipse
However, a>b> 0
Actually, an elliptical curved reflecting surface RG0 having a design value of the major axis a of 10 mm and a design value of the minor axis b of 7 mm is formed and reflected by the curved reflecting surface RG0, as shown in the figure. The point at which the light emitted from the LED 1 is first reflected by the reflective surface RG1 is on the near side, the point at which the light emitted from the LED 2 is first reflected by the reflective surface RG1 is substantially at the center, and the light emitted from the LED 3 is at the reflective surface RG1. The first reflecting point is on the far side. Although not necessary in this embodiment, the tip of the curved reflecting surface RG0 is cut vertically according to the reflection efficiency, molding conditions, etc., and the vertical reflecting surface is formed together with the support frame, so that the light of the LED is more It can be reflected in the reading main scanning direction, and the illuminance of the LED light source LA is increased accordingly. In addition, the size of the LED light source LA can be reduced to make the entire apparatus compact.

[Shape Arrangement of Reflecting Surface RG1]
Further, the reflecting surface RG1 that reflects the light of the LED and irradiates the reading main scanning direction of the read document in a line shape,
As shown in the side view (b) of FIG. 12, the light guide is formed by a surface that is arranged at substantially equal intervals and is thinned from the outside of the light guide into an inverted V-shaped section or an inverted saddle-shaped section. Further, as shown in the plan view (a), the width is formed such that the central portion is as narrow as the width d2, and the farthest side is wide as the width d1. Each width d of the reflecting surface RG1 is such that when the light receiving means CCD, which will be described later with reference to FIG. 13, reads the white reference, the amount of received light is substantially uniform in the reading main scanning area according to the above cosine fourth law. The amount of reflected light can be increased or decreased to reinforce the attenuation. Specifically, the width d1 is approximately 2 mm, and the width d2 is approximately 5 mm.

[LED arrangement]
The position of the LED is determined by setting the condition of the curved reflecting surface RG0 [in this case, the elliptical curved surface has a major axis a value and a minor axis b value] and a critical angle specific to the light guide RG. I can do it. If the position of this LED is determined, the main scanning line direction end Q1 of the curved reflective surface RG0 facing the light emitting surface of the LED is determined, and the reflective surface shape of the support frame that wraps around the curved reflective surface RG0 is set. Therefore, at least the arrangement of the LEDs is appropriately adjusted and arranged outside the critical angle region at the main scanning line direction end Q1 of the curved reflecting surface RG0 wrapped in the reflecting surface of the support frame. When the LED actually has a three-chip configuration, each LED is appropriately adjusted and arranged outside the critical angle region at the main scanning line direction end Q1 of the curved reflecting surface RG0.

Specifically, the arrangement of each LED is appropriately adjusted in the reading main scanning direction with respect to the arrangement position (intervals P1, P2) of LED1 and LED2 with reference to the light quantity distribution of LED1 that illuminates the vicinity and increases the reflected light quantity level. As the LED light source, a light amount distribution that reinforces the attenuation of light by the cosine fourth law of the condenser lens LE as shown in FIG. 13 is formed. Specifically, as shown in FIG. 11, the indicated dimension L0 from the main scanning line direction end Q1 of the upper curved reflecting surface RG0 of the LED 1 is a line Q1-Q2 where the critical angle (A) is set at about 42 degrees. The position is adjusted in accordance with the light quantity distribution with reference to the determined retreat distance Lb of distance 6.3 mm. The distance between LED1 and LED2, and the distance between LED2 and LED3 are set such that the minimum width of the read document S is approximately 297 mm, and the total length in the main scanning line direction of the light guide RG from the elliptical center of the light guide RG is approximately 350 mm. In this case, the reference value is determined to be approximately 2 mm in both cases, and each interval is adjusted and set according to the light amount distribution based on this reference value.

[Light intensity distribution of LED light source]
Next, the light quantity distribution of the LED light source will be described. As shown in FIG. 13, when the light receiving means CCD reads the white reference, the light according to the cosine fourth law of the condenser lens LE attenuates and becomes a dotted line. In the main scanning region LV1, the light amount distribution indicated by the one-dot chain line of the LED 1 and the two-dot chain line of the LED 2 are indicated with reference to the light amount distribution indicated by the three-dot chain line of the LED 3 so that the received light amount becomes substantially uniform. The arrangement of each LED1, LED2, and LED3 is adjusted to obtain a light quantity distribution. As a result, the light amount distribution LA-Lv of the LED light source shown in the figure has illumination characteristics that reinforce the light amount of the portion where the light is attenuated by the cosine fourth law.

[Second Embodiment]
The second embodiment will be described below with reference to FIGS. In the second embodiment, the above-described LED light source of the present application is used as a light source of a contact sensor type image reading apparatus.

[Configuration and Operation Overview of Image Reading Apparatus]
14A and 14B are configuration diagrams showing an outline of a contact sensor type image reading apparatus according to the present invention. FIG. 14A is a configuration diagram of the apparatus, and FIG. 14B is an overview of the contact sensor as viewed from the side of a read document. FIG.

First, the overall configuration of the apparatus will be described with reference to FIG. A platen P on which the read original S is placed, an LED light source LA that illuminates the original face of the read original S placed on the surface on which the platen P is placed, and reflected light from the original face of the read original S is collected. And a light receiving means CCD for receiving the image light of the read original S collected from the cell hook lens SHL.

Then, as shown in FIG. 6A, the image reading apparatus moves the carriage body from the left corner to the right corner of the paper at a speed V along the original surface of the read original S, and receives the original face of the read original S. Means to read with CCD.

[Light intensity distribution of LED light source]
Next, the light quantity distribution of the LED light source applied to the second embodiment will be described with reference to FIG. The same figure (a) shows the light quantity distribution of the LED light source manufactured based on this invention. FIG. 5B shows the LED light source, and the upper reflection surfaces of the three LEDs are formed in the curved reflection surface RG0 shape (elliptical shape) described above.

For this reason, as shown by A in the figure, the light amount at the LED end of the light guide RG is attenuated compared to the light amount distribution (dotted line) of the conventional LED light source described above, and the light amount unevenness in the main scanning line direction is eliminated. ing.

Next, the figure (c) shows the light quantity distribution of the LED light source after further adjusting the arrangement relationship of the LEDs with respect to the above-mentioned LED light source. FIG. 4D shows the configuration of the LED light source.

The difference between FIG. (D) and FIG. (B) is that, in FIG. 11 (b), the curvature forming the curved reflecting surface RG0 of the light guide RG is long axis a = 10 mm as shown in FIG. By determining the ellipse [X ² / a ² + Y ² / b ² = 1] shape with a short axis b = 7 mm, the position L1 of the LED 1 on the front side in the main scanning line direction is the distance in the critical angle region described above. When L0 = 6.3 mm, the minimum width of the read document S is set to approximately 297 mm, and the total length in the main scanning line direction of the light guide RG from the center of the light guide RG is approximately 350 mm, LED1 and LED2 , LED2 and LED3 each have a distance p1 = 2 mm, whereas in FIG. (D), the LED1 and LED2 distance p2 and the LED2 and LED3 distance p3 are based on a reference value of 2 mm, respectively. It is adjusted according to the light intensity distribution.

As a result, the amount of light at the LED end of the light guide RG is further attenuated as shown in FIG. 7C, and unevenness in the amount of light in the main scanning line direction can be eliminated.

As described above, by adjusting the light quantity distribution of the LED light source according to the usage pattern, it can be used as a light source of an optical reduction type image reading apparatus and as a light source of a contact sensor type image reading apparatus. .

[Other Examples]
In the above embodiment, in order to form the light quantity distribution LA-Lv of the LED light source in order to reinforce the attenuation of light by the cosine fourth law of the condenser lens LE, first, the width of each reflecting surface body RG1 is individually set. Second, the receding position Lb determined from the critical angle (A) of the LED 1 and the intervals P1, P2 of the LED 1, LED 2, LED 3 are appropriately adjusted, but adjustment is possible only by the width of each reflecting surface RG1. If so, the adjustment may be made only by adjusting the width of the reflecting surface RG1, or by adjusting only the arrangement of each LED as long as the adjustment is possible due to the arrangement relationship of the LED1, LED2, and LED3.

Further, the reflecting surface of the reflecting surface body RG1 may have a shape that is in a semicircular shape other than the shape that is in a V shape as described above.

The end curved surface of the light guide RG is best an ellipse, but may be a spherical surface other than the ellipse. If the ellipse is used, the height of the light guide can be reduced compared to the case of a spherical surface, and the overall apparatus is excellent in compactness.

Moreover, by making the surface of the board | substrate which attaches an LED light source into white silk printing, the reflective efficiency of an LED light source can be raised and the LED light source which is bright by that much can be provided.

In the embodiments described above, the LED light source in which the LEDs are arranged on one side of the light guide RG is disclosed. Naturally, the LED light source RG is arranged at both ends of the light guide RG, and the curved reflection surface RG0 shape (elliptic constant a, b) By adjusting the receding position of the LED from the critical angle region, the width of the reflecting surface body, and the like according to the required amount of illumination light, it is possible to provide a bright LED light source optimal for the image reading apparatus.

Furthermore, when it is not sufficient to adjust the curved reflection surface RG0 shape, LED arrangement, etc. according to the required illumination light amount according to the device specifications, particularly when two or more LEDs are used, each LED is turned on. It can be adjusted by forming a PWM circuit in the lighting control means and controlling the lighting time of each LED.

In addition, when adjusting the arrangement of the LEDs described above according to the required amount of illumination light, adjustment is possible by moving the position of each LED in a direction perpendicular to the main scanning line direction as shown in FIG. It is.

CCD light receiving means LE condenser lens (lens means)
LA LED light source LED light emission source P platen Q1 main scanning line direction end RE support frame RG light guide RG0 curved surface RG1 reflecting surface S reading document SHL self-hoc lens (lens means)

Claims (10)

It consists of an LED that serves as a light emitting source and a light guide that internally reflects the light of the LED and diffuses it into a main scanning line,
A plurality of light guides arranged in the main scanning line direction with a predetermined interval in a state where they face each other in the inner surface reflection light path of the light guide, and reflect the light of the LED toward the outside of the light guide along the main scanning line. With a reflective surface
An LED light source characterized in that the length of each reflecting surface in the direction orthogonal to the main scanning line direction is appropriately adjusted according to the amount of light reflected. 2. The LED light source according to claim 1, wherein the reflecting surface body is formed by a surface that is thinned into an inverted V-shaped cross-section or an inverted cross-sectional shape from the outside of the light guide. The LED light source according to claim 1, wherein the LED is a white LED. 4. The LED light source according to claim 3, wherein the white LED is a single-chip LED including a blue LED chip and a yellow phosphor. 5. The LED light source according to claim 4, wherein the yellow phosphor comprises a YAG (yttrium, aluminum, garnet) yellow phosphor. 4. The LED light source according to claim 1, wherein a plurality of the LEDs are arranged along the main scanning line direction. 7. The LED light source according to claim 6, wherein two or more LEDs are arranged at different intervals in the main scanning line direction. A platen on which the document to be read is placed;
An LED light source for illuminating a read document placed on the platen;
Lens means for condensing the reflected light from the main scanning line of the read original illuminated by the LED light source;
A light receiving means for receiving reflected light from the main scanning line of the read original collected by the lens means;
An image reading device comprising:
The LED light source is
An LED as a light source;
A light guide for diffusing an illumination area of an LED that illuminates a read original placed on the platen to at least a main scanning line width of the read original;
Consists of
A plurality of light guides arranged in the main scanning line direction with a predetermined interval in a state where they face each other in the inner surface reflection light path of the light guide, and reflect the light of the LED toward the outside of the light guide along the main scanning line. With a reflective surface
An image reading apparatus characterized by appropriately adjusting the length of each reflecting surface in the direction perpendicular to the main scanning line direction according to the amount of light to be reflected. 9. The image reading apparatus according to claim 8, wherein each length of the reflecting surface body is adjusted so that a light amount distribution in a main scanning line direction reflected from a white reference surface and received by the light receiving unit is substantially uniform. The lens means is a condenser lens for dimming light passing therethrough according to the cosine fourth law,
10. The image reading apparatus according to claim 9, wherein each length of the reflecting surface body is obtained by interpolating the amount of light that passes through at least the condenser lens and is attenuated according to the cosine fourth law with the amount of reflected light.