JP2002357875A - Light source and image reader using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source for an image reader capable of attaining uniform enission luminance. SOLUTION: The width and thickness of an electro-luminescent film are decided in accordance with an electric field. Besides, many contact pints between a lead and an electrode are arranged in various positions so as to prevent a voltage drop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source.
The present invention relates to a light source of an image reading device and an image reading device using the light source.

[0002]

2. Description of the Related Art Equipment such as a copier, a printer, a facsimile using an image reading apparatus, or a multi-function printer having the functions of a facsimile, a copier and a printer are known as paper or sheet-shaped recording media (hereinafter, referred to as "paper").
(Referred to as a manuscript).

As a light source of the image reading apparatus, a reduction optical system (reduction CCD system) has been well known. However, this configuration can obtain a sufficient light emission luminance and increase the depth of focus of a lens. In addition, there is an advantage that a clear image can be obtained even when the document is floating from the document surface. However, because of the large size,
In order to reduce the thickness, as shown in FIG. 17, a close contact method is used in which information from an original is guided to a sensor in the same size erect.

That is, the LED array 112 as a light source
Are symmetrically arranged diagonally above the document surface, and the light irradiated on the document surface is received by the following rod lens array 121 arranged at an intermediate upper position between the two LED arrays 112. The LED array 112 is, for example, as shown in FIG.
As shown in FIG. 7, a large number of LED elements 125 are arranged on a substrate 124 in the main scanning direction. As shown in FIG. 19, the rod lens array 121 first has a predetermined length,
A columnar rod lens 122 having a predetermined diameter is arranged in a plurality of rows adjacent to each other by a predetermined number of lengths corresponding to the length of the LED array 112, and is sandwiched between substrates 124.

According to this configuration, a reduction optical system (reduction CC)
D method), the original surface 106 and the rod lens 1
Since the distance from the device 22 can be reduced, the entire device can be considerably reduced. Further, by reducing the focal length of the rod lens 122, a thinner device can be expected. To reduce the focal length of the rod lens array 121, the diameter of the rod lens 122 may be reduced. However, if the diameter of each rod lens 122 is reduced, crosstalk between each rod lens 122, flare light, etc. Optical noise increases and the MTF (modula
The value of the transfer function decreases. Accordingly, the applicant of the present application has proposed a configuration of a rod (fiber) lens array having less optical noise (described later) in Japanese Patent Application No. 2000-224156.

Further, since the light source used in the LED array 112 is a set of point light sources,
Is used, uniformity of the illuminance on the document surface 106 cannot be secured unless a certain distance is maintained between the document surface 106 and the light source. In this regard, the LED array 1
There is a limit in promoting the thinning and miniaturization of the contact-type device using the device 12. Therefore, the applicant of the present application has proposed in Japanese Patent Application No. 2000-217561 or the like using a layered electroluminescence as a light emitting medium for the purpose of further reducing the thickness and size.

For example, as shown in FIG. 20, a transparent electrode layer 102 is formed on a glass substrate or a transparent substrate 101 such as a transparent resin which is long in the scanning direction, and a light emitting layer 100 as a light emitting medium is formed on the back surface thereof. Further, a metal electrode layer 103 is laminated on the back surface. By applying a predetermined voltage to the two electrode layers 102 and 103 having this configuration, light emission of a predetermined intensity can be obtained from the front surface of the transparent electrode 102. RG when you want to get a color image
B. Three types of light emitting layers that emit three types of light of B
01 will be formed.

The configuration of the image reading apparatus using the light source configured as described above will be described later.
Although the configuration is almost the same as the configuration using No. 12, uniform light is emitted from the light source to the document, so that the light source can be brought closer to the document. Further, by reducing the diameter of each rod lens 122 constituting the rod lens array to shorten the focal length, a thinner image reading apparatus can be expected to be constructed. The light emitting layer 100 is not limited to vapor deposition or the like used for forming a general thin film, and may be formed by printing, coating, or the like.

[0009]

As described above, even with a light source using electroluminescence as a light-emitting medium, the light emission luminance of the light source depends on the position, particularly the position in the longitudinal direction, due to various factors. The factor may be a resistance of the electrode layer (especially a transparent electrode) or the like. That is, the emission luminance of the electroluminescence at a portion far from the connection point P between the lead and the transparent electrode layer 102 or between the lead and the metal electrode layer 103 is lower than the emission luminance at the portion near the connection point P. small.

[0010] Further, as a factor in which the light emission luminance of the light source depends on the position, a variation in the thickness of the electroluminescence may be considered. This is because it is difficult to manufacture electroluminescence having a thickness equal to or greater than a certain length.

If the light emission luminance of the light source is not uniform, uniform illuminance cannot be obtained on the original surface 106, so that the sensor 1
The image density read by 08 depends on the position of the document.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and has as its object to provide a light source for an image reading apparatus capable of obtaining uniform light emission luminance.

[0013]

The present invention employs the following means to achieve the above object. That is, a light emitting layer is formed on a transparent substrate piece, and in a light source that emits light by applying a voltage from the front and back of the light emitting layer, a plurality of light source pieces each having the light emitting layer formed on a transparent substrate piece shorter than the entire length of the light source. Multiple pieces are joined in the longitudinal direction to obtain the required length.

Thus, a light source having a uniform light emission luminance can be obtained by forming a light source using a light source piece having a light emitting layer having a length in which the thickness of the light emitting layer can be easily adjusted (easily made uniform). .

Since the light emitting layer is not laminated on the end face of the light source piece as shown in FIG. 2 for sealing treatment, the light emission luminance of the light source formed by joining the light source pieces is remarkably at the joint portion. Become smaller. Therefore, the width of the light emitting layer in the vicinity of the joint portion of the light source piece is increased or the film thickness is reduced, so that the light emission luminance of the joint portion is compensated. Electroluminescence can be used as the light emitting layer.

Further, the above light source can be applied to an image reading device.

[0017]

(Embodiment 1) FIG. 1A is a plan view showing a light source 5 for an image reading apparatus according to the present invention.
FIG. 1B is a sectional side view. The light source 5 is configured by joining a plurality of light source pieces 50α, β. The light source pieces 50α, β ... have the same configuration as the conventional light source. That is, a transparent electrode layer 53α is formed on a glass substrate or a transparent substrate piece 52α such as a transparent resin which is long in the scanning direction.
are formed on the transparent electrode layers 53α, β,... as light emitting media, and the light emitting layers 5α, β,.
The metal electrode layers 54α, β... Are formed on 1α, β. In the present embodiment, the light emitting layers 51α, β ...
It is assumed that electroluminescence is used as a material for the above. The lead 10 is connected to the transparent electrode layer 53, and the lead 11 is connected to the metal electrode layer 54.

Since the electroluminescence used above is easily affected by humidity, the light source piece 5
The sealing process is performed for the purpose of preventing intrusion of moisture in 0α, 50β... And for preventing physical damage of electroluminescence. That is, the light source pieces 50α, 50β ...
Is created as follows.

As shown in FIG. 2, first, a transparent substrate piece 52α
0.3 to 0.5 mm from the end face 56 of the sealing portion 57α
In addition, as described above, the transparent electrode layer 53α and the light emitting layer 5
1α and a metal electrode layer 54α are stacked. Next, an adhesive resin 58 such as an epoxy resin for sealing is applied to the sealing portion 57α. Finally, a sealing glass 59α is formed on the metal electrode layer 54α and the epoxy resin 58.
Is covered.

The light source pieces 50α, 50 thus prepared
are sequentially joined together with an adhesive or the like to form one light source 5. Therefore, each light source piece 50α,
The length in the longitudinal direction of 50β...
.., the metal electrode layers 54α, 54β.
.. are formed such that the film thickness of α, 51β... can be formed uniformly (for example, by a vapor deposition method) (about 80 mm), so that a document placed at a predetermined distance from the light source 5 regardless of the length of the light source 5 The illuminance on the surface can be made uniform.

(Embodiment 2) By the way, the light emitting layers 51α, 51β constituting the light source pieces 50α, 50β... Of FIG.
Are rectangular, and the contact portions of the light source pieces 50α, 50β,... Are parallel to the short sides of the light source pieces 50α, 50β,. Therefore, when the light source pieces 50α, 50β,.
There is no light emission due to β. for that reason,
The light emission luminance of the light source 5 obtained by joining the light source pieces 50α, 50β... Becomes almost zero at the sealing processing sections 57α, 57β. Therefore, in the present embodiment, the attenuation of the emission luminance is compensated as follows.

FIG. 3 is a diagram showing the present embodiment. The width of the light emitting layer 51 within 10 mm from the end 56 of each light source piece 50α, 50β... Is wider than the width of the other portions.

The width of the light emitting layers 51α, 51β... Becomes smaller at the center of the light source pieces 50α, 50β. Can be compensated for.

(Embodiment 3) FIG. 4 is a block diagram showing still another embodiment of the present invention. In the first embodiment, since the shape of the light emitting layer 1 of the light source piece 50 is rectangular, the light emission luminance near the end face 56 is almost zero. Therefore, if the end face 56 is formed to have a certain angle with respect to the short direction of the transparent substrate piece 52, the above-mentioned disadvantage will be reduced.
That is, as shown in FIG. 4, each light source piece 50α, 50β.
And the light-emitting layers 51α, 51β,.
For example, when the light source pieces 50α and 50β are joined, the light source piece 50α and the light source piece 50β are configured to overlap in the short direction. With this configuration, the light emitting layer 51 is formed.
The α, 51β sealing processing sections 57α, 57β spread in the longitudinal direction and are distributed, so that the sealing processing sections 57 can be prevented from being concentrated on a specific portion. still,
The light-emitting layer 51α of the light source piece 50α has a light-emitting layer 51α in order to prevent the light emission luminance of the light source 5 having the parallelogram-shaped light source pieces 50α, 50β.
Length Q of light source piece 50β overlapping light emitting layer 51β
Is preferably at least five times the distance I between the light emitting layers 51α and 51β (the length of the missing part 40). Further, the width W of the light emitting layers 1α and 1β is set to 1.7, which is the overlapping length Q.
It is desirable to make it twice or less.

Also, as shown in FIG.
It may be configured in a character shape. In the case of this configuration, the width of the light source 5 in the overlap portion J where the light emitting layer 51α of the light source piece 50α and the electroluminescence 51β of the light source piece 50β overlap is made wider than other portions.
By increasing the width of the light source 5, it is possible to increase the width of the light emitting layer 51 of the overlap portion J.

In the structure shown in FIG. 5, in order to obtain a light source whose emission luminance does not depend on the position in the longitudinal direction, a light emitting layer 51 is provided.
It is desirable that the length M in the longitudinal direction of the light source 5 where α and the light emitting layer 51β overlap is set to be at least five times the distance K between the light emitting layers 51α and 51β.

Further, in order to reduce a decrease in light emission luminance at the joint portion, for example, as shown in FIG.
Light emitting layer 51 formed at the joint of 0α, 50β,.
Is desirably configured to be eccentric from the center of the light source 5 in the lateral direction. When the missing part 40 is eccentric,
It is desirable that the width S of the protrusion formed at one end of each of the light source pieces 50α, 50β,.

(Embodiment 4) Light source pieces 50α, 50β...
Of the light-emitting layers 51α, 51β... In other words, under the same inter-electrode potential, if the thickness of the light emitting layer 51 is small, the electric field intensity increases, and the light emitting layer 5
The emission luminance of 1α, 51β,. Therefore, as shown in FIG. 6, the object of the present invention can be achieved by making the thickness of the light emitting layer 1 within 10 mm or less from the end face 56 smaller than the thickness at the center.

(Embodiment 5) Further, as shown in FIG. 7, light is emitted from an edge light emitting layer 22 and a central light emitting layer 21 made of electroluminescence as shown in FIG. The layer 51 may be configured. For example, the sealing processing portions 57 to 5 of the transparent substrate piece 52
Within mm, the transparent electrode layer 32 of the edge emitting layer 22 is stacked, the edge emitting layer 22 is stacked thereon, and the metal electrode layer 42 of the edge emitting layer 22 is further stacked thereon. The central light emitting layer 21 is located inside the edge light emitting layer 22.
Of the central light emitting layer 21
, And the metal electrode layer 41 of the central light emitting layer 21 is further laminated thereon. The transparent electrode layers 31 and 32 are connected to the lead 10, and the metal electrode layers 41 and 42 are connected to the lead 11. Here, in order to obtain a constant light emission luminance at the joint portion, the light emission control means H for controlling the light emission of the central light emitting layer 21 and the end light emitting layer 22 is provided at the end portions through the leads 10 and 11. Transparent electrode layer 3 of light emitting layer 22
2. A voltage higher than that between the transparent electrode layer 31 and the metal electrode layer 41 of the central light emitting layer 21 is applied between the metal electrode layers 42. Accordingly, the light emission luminance of the end light emitting layer 22 is increased. By forming the light source 5 by joining such light source pieces 50, the light emission luminance of the light source 5 does not depend on the position in the longitudinal direction. Further, in order to obtain the light source 5 that emits light with uniform luminance at the position in the longitudinal direction, the thickness of the end light emitting layer 22 may be configured to be thinner than that of the central light emitting layer 21. (Embodiment 6) The light source 5 configured as described above is, for example, a light source unit 15 of an image reading apparatus as shown in FIG.
Can be used as the light sources 5a and 5b. Light source 5
a and 5b are obliquely upward with respect to the document reading position Pa,
They are arranged symmetrically. Further, a fiber lens 14 described later is arranged vertically above the reading position Pa.

In this configuration, since the light sources 5a and 5b emit light from the surface, the light sources 5a and 5b
The illuminance on the reading position Pa does not depend on the positions of the light sources 5a and 5b in the longitudinal direction. By bringing the light sources 5a and 5b closer to the reading position Pa, the size of the light source unit 15 including the light sources 5a and 5b and the fiber lens 14 can be reduced. Further, by reducing the size of the light source unit 15, it is possible to reduce the size of the entire image reading apparatus.

As a result of measuring the illuminance at the reading position using the light source unit 15 using the light source 5 as the light sources 5a and 5b, the following points were confirmed. Central part O of light sources 5a and 5b
Even if the distance between the reading position Pa and the reading position Pa is reduced to 1 mm, uniform illuminance can be obtained. Note that the LED arrays 112 (FIG.
In the case of using 8), if the distance between the central portion O of the LED element 125 and the reading position Pa is 7 mm or less, uniform illuminance cannot be obtained at the reading position Pa. The light source 5 has a missing portion 40 at a joint portion of the light source pieces 50. When light sources 5 are used as the light sources 5a and 5b in order to alleviate a decrease in light emission luminance due to the missing portion 40, the light sources 5 are arranged as follows. The missing portions 40a and 40b formed in the light sources 5a and 5b are arranged so as not to be located at the same position in the longitudinal direction of the condenser lens 14. For example, as shown in FIG. 9A, the light source 5a is arranged so as to be shifted in the longitudinal direction of the condenser lens 14 with respect to the light source 5b. For example, it is preferable that the shift distance is 2 mm or more when the total length of the light sources 5a and 5b is 320 mm and the lengths of the missing portions 40a and 40b of the light sources 5a and 5b are 1 mm. By arranging in this way, as shown in FIG.
a and 40b are arranged at the same position in the longitudinal direction of the condenser lens 14 as compared with the case where the light sources 5a and 5b are arranged.
The variation in illuminance of the reading position Pa due to the missing portions 40a and 40b is reduced. 9 (b) and 10 (b)
Shows the illuminance distribution at the reading position Pa when the light source 5 is arranged as shown in FIGS. 9A and 10A.

The missing portions 40a and 40b are connected to the condenser lens 1
The following configuration is also conceivable as a configuration for arranging at a position distant from the longitudinal direction of 4. That is, the light source 5
a or another light source piece 50 to the light source pieces 50 at both ends of the light source 5b.
This is a configuration using a shorter light source piece 50.

(Embodiment 7) In the configuration of FIG.
In order to bring the fiber lens 14 closer to the reading position Pa while keeping the depth of focus of the fiber lens 14 deep, the diameter of the fiber constituting the lens 14 must be made smaller than the diameter of the conventional rod, or FIG. Original surface 6 shown in
It is necessary to increase the distance (conjugate length) between the sensor and the sensor 8. In the conventional rod lens 122, the conjugate length is increased to keep the depth of focus deep because there is a limit in reducing the diameter. However, when the conjugate length is increased, the image reading apparatus can be made thinner and smaller. Would be contrary to trying to Therefore, as shown in FIG. 11, the fiber lens 14 is configured by bundling optical fibers 140 having a small diameter, that is, 0.5 mm or less. As a result, the focal length of the fiber lens 14 can be shortened and the depth of focus can be increased, the overall optical path length can be suppressed, and the image reading apparatus can be made thinner and smaller. And phenomena such as flare become remarkable. Therefore, FIG.
As shown in FIG. 2, a light absorbing layer 143 is formed around each optical fiber 140 having a predetermined length, or the optical fiber 1 having a predetermined length is formed as shown in FIG.
A plurality of fibers 40 are bundled, and a fiber bundle 144 having a light absorbing layer 141 formed on the outer periphery thereof is formed. The fiber bundle 144 satisfies the following relationship in order to prevent phenomena such as crosstalk and flare. That is, as shown in FIG. 13, the value obtained by dividing the length (outer diameter) Y of one side of the fiber bundle 144 by the length N of the optical fiber 140 is the difference between the central axis Z of the optical fiber 140 and the incident light V. The opening angle ω is set so as to satisfy a relationship that is smaller than the tangent value of the opening angle ω, which is the angle between them. The aperture angle ω is the maximum angle at which light can be transmitted normally. FIG.
3 shows a state in which the light V is incident on the optical fiber 140 at the maximum angle at which the light can be transmitted normally, so that in this figure, the central axis Z of the optical fiber 140 is shown.
And the incident light V corresponds to the aperture angle ω. A plurality of optical fibers 140 each having the light absorbing layer 143 formed thereon or the fiber bundle 14 having the light absorbing layer 141 formed thereon are used.
4 are filled in parallel in the radial direction with the length direction of the optical fiber 140 turned up and down in a mold having a predetermined shape whose top and bottom are open, and the adhesive is filled in the gap between each optical fiber 140. To solidify and deframe. The predetermined shape of the mold frame is a shape necessary for an image reading apparatus such as a copying machine using the fiber lens 14 to exhibit its original function, and is usually a strip shape having a length perpendicular to the document conveying direction. Become. Further, as shown in FIG. 14, if necessary for molding, the optical fiber 140 alone or the fiber bundle 144 is sandwiched in the mold by a substrate 142 made of opaque glass or resin.
The substrate 142 and the single optical fiber 140 or the fiber bundle 144 may be bonded to each other by the above-described method.

Further, a plurality of optical fibers 140 each having the light absorbing layer 143 formed thereon or a plurality of fiber bundles 144 each having the light absorbing layer 141 formed therein may be, for example, the optical fiber 1.
The length direction 40 is closely arranged in parallel in the radial direction, and the gap is filled with an adhesive, sandwiched between two opaque glass or resin substrates 142 having a predetermined shape, and thermocompression-bonded. Is solidified (not shown).

The refractive index of the optical fiber 140 is gradually reduced toward the outer periphery in a direction perpendicular to the axis, and in principle, light is converged toward the center even without the light absorbing layers 141 and 143. However, when the diameter is reduced as a practical problem, the crosstalk or the flare phenomenon becomes remarkable, and it is necessary to form the light absorbing layers 141 and 143.

The light absorbing layers 141 and 143 can be formed by coating, dipping, or vapor-depositing a black resin. The adhesive used when the mold is filled with the optical fiber 140 alone or the fiber bundle 144 may be a conventional adhesive, but may be a black or other adhesive that can prevent the crosstalk or the flare phenomenon. It is preferable to use these adhesives as the light absorbing layer 141. Here, when the light-absorbing layer is also used with the black adhesive or the like, the adhesive is formed on the optical fiber 140 alone or on the outer periphery of the fiber bundle 144, and the upper and lower portions are opened in the same manner as described above. The fiber lens 14 is manufactured by a method using a mold having a predetermined shape or a method of sandwiching and thermocompression between two substrates 142. Of course, in this manufacturing, the adhesive such as black is spread over the entire optical fiber 140 alone or the outer circumference of the fiber bundle 144. As the adhesive, for example, glass or resin having a low softening point can be used, and the softening point is determined by the optical fiber 140 and the substrate 142 constituting the fiber lens 14.
It is necessary to be lower than such materials.

Here, the diameter of the optical fiber 140 provided in the fiber lens 14 is set to about 0.1 mm, which is 1/6 of the diameter of the conventional rod lens.
When the length of the reading device 40 is about 4.0 mm, which is 1/6 of the length of the rod lens, the reading device 120 shown in FIG.
a · 120b has a thickness in a direction perpendicular to the surface of the document 9 of about 1/6 which is 1/6 that of a conventional contact type image reading apparatus.
0 mm.

FIG. 15 shows an image reading apparatus to which the present invention is applied. In this case, both sides of the image reading apparatus can be read. Of course, this image reading device may be used for facsimile or a copier.

As in the prior art, the original 9 drawn into the apparatus by the pick roller 151 constituting the original transport section 162 is fed into a horizontal transport path 133 by upper and lower feed rollers 152a and 152b. A belt roller 164 that receives the document 9 from the upper and lower feed rollers 152a and 152b and conveys the document 9 backward is provided in the conveyance path 133, and is controlled to operate when the leading end of the document 9 reaches a predetermined position. It has become.

Near the front end of the horizontal transport path 133, two upper and lower readers 120a and 120b are arranged, and when the original 9 is transported, both sides of the original 9 are simultaneously read at the upper and lower reading positions Pa and Pb. ing.

Here, the lower reading device 120b is required to have a large depth of focus in order to read a document floating from the document surface 136, for example, an open book. Therefore,
By using the fiber lens 14 shown in FIG. 11 and the light source 5 of the present invention for the lower reader 120b, the entire reader can be designed to be thin. of course,
By using the fiber lens 14 shown in FIG. 11 and the light source 5 of the present invention for the reading devices 120a and 120b on both the upper and lower sides, the thickness of the image reading device can be further reduced.

As described above, when reading images on both sides of the original 9, if the irradiation light from each light source of the upper and lower reading devices 120 a and 120 b irradiates the same upper and lower positions, the mutual irradiation light Will interfere. Therefore, the arrangement of the readers 120a and 120b is shifted to such an extent that the light emitted from each light source of the readers 120a and 120b is not at the same position in the upper and lower portions, thereby preventing the above-described interference.

The reading devices 120a and 120b
Has reading characteristics such as a γ value (density vs. sensor output value) and gradation characteristics which affect each read information obtained by reading images on both sides of the document 9. Here, it is desirable that the print quality of the image printed on both sides of the paper or the like provided in the copying machine be the same, and for that purpose, the information read from the upper reading device 120a and the lower reading device 120b are used.
It is necessary that the information read from the same is the same. Therefore, the copying machine is provided with a reading correction means 132 so as to correct the reading characteristics of the reading devices 120a and 120b so as to be identical.

For example, in the above γ value, the relationship between the amount of reflected light from the document 9 (total amount of light flux for a predetermined time), the output of the sensor unit, and the γ value is generally γ, as shown in FIG.
> 1 and γ = 1, or γ <1. here,
When the sensor output is increased at an arbitrary light amount value a, the reading correction unit 132 corrects the γ value so that γ> 1. Similarly, γ =
1 or γ <1 to adjust the light amount and the sensor output value, so that the upper and lower reading devices 120a
Make the read information of 120b the same.

In addition, of the upper and lower reading devices 120a and 120b provided in the copying machine, the upper reading device 120
a may be fixed, and the lower reading device 120b may be of a movable type.
Method).

In the image reading operation in this case, first, the original 9 inserted into the original transport section 162 is moved by the pick roller 151 and the feed rollers 152a and 152b.
Is transported to the transport unit 133. Thereby, the original 9
Is sent to the horizontal transport path 133 while being read by the fixed reading device 120a.
A reading table made of glass (not shown) is provided below 33.
The belt roller 164 temporarily stops while the original 9 is placed on the reading table, and the above-described fluorescent lamp (ie, the reading position Pb) as a light source moves. When the reading by the reading device 120b is completed, the belt roller 164 is further operated to discharge the document 9.

As described above, the lower reading device 120b is of a movable type using a reduced optical system (reduced CCD system) and the current copy machine capable of placing the original 9 on the glass platen from above. By adopting the same configuration as that described above, it is possible to cope with a document such as a book which cannot be fed by the document transport unit 162.

Of course, as described above, the reduction optical system (reduction C
Instead of moving the lower reading device 120b using the CD method, a configuration is also possible in which the fluorescent lamp is fixed at a predetermined position and reading is performed in accordance with the document 9 conveyed by the belt roller 164.

The above is a case where the image reading apparatus using the light source according to the present invention is applied to a copying machine. However, the present invention can be similarly applied to a facsimile, an image reading apparatus, a multifunction printer, or the like.

[Brief description of the drawings]

FIG. 1 is a plan view and a side view showing a light source for an image reading apparatus according to the present invention.

FIG. 2 is a diagram showing a partial cross section of a light source piece.

FIG. 3 is a diagram showing a light source having a wide electroluminescent layer near an end face.

FIG. 4 is a diagram showing a light source whose end face is inclined with respect to the short direction of the light source.

FIG. 5 is a diagram showing a light source constituted by a substantially L-shaped light source piece.

FIG. 6 is a cross-sectional view of a light source piece having a thin electroluminescent layer near an end face.

FIG. 7 is a configuration diagram showing a light source piece including a central light emitting layer and an edge light emitting layer.

FIG. 8 is a diagram showing a light source unit.

FIG. 9 is a diagram illustrating a plan view of a light source unit and an illuminance distribution at a reading position.

FIG. 10 is a diagram showing a plan view of a light source unit and an illuminance distribution at a reading position.

FIG. 11 is a perspective view of a fiber lens included in the image reading apparatus.

FIG. 12 is a perspective view of another fiber lens included in the image reading apparatus.

FIG. 13 is a perspective view of an optical fiber constituting a fiber lens.

FIG. 14 is a sectional view taken along line XX ′ of the fiber lens.

FIG. 15 is a configuration diagram of a copying machine that performs duplex reading.

FIG. 16 is a diagram illustrating an example of correction based on a γ value of a reading correction unit.

FIG. 17 is a configuration diagram of a conventional contact image reading apparatus.

FIG. 18 is a perspective view of a light source provided in a conventional contact image reading apparatus.

FIG. 19 is a perspective view of a rod lens array included in a conventional contact image reading apparatus.

FIG. 20 is a perspective view of a light source using an electroluminescence film.

[Explanation of symbols]

 51 light emitting layer 52 transparent substrate piece 53 transparent electrode layer 54 metal electrode layer P connection point

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H109 AA02 AA15 AA27 AA38 AA46 AA94 3K007 AB02 BA02 DB03 5C051 AA01 BA04 DA02 DB01 DB28 DC05 5C072 AA01 BA01 CA02 CA09 CA15 DA25 EA07 LA18 WA02 XA01

Claims (22)

[Claims] 1. A light source in which a light emitting layer is formed on a transparent substrate and a voltage is applied from the front and back of the light emitting layer to emit light, the light source piece having the light emitting layer formed on a transparent substrate shorter than the entire length of the light source. A light source for an image reading apparatus, wherein the light source has a required length by being joined in a plurality of longitudinal directions. 2. The light source of the image reading device according to claim 1, wherein a width of an end portion of the light emitting layer of the light source piece is wider than a width of a central portion. 3. The light source of the image reading device according to claim 1, wherein an end face in a longitudinal direction of the light source piece is inclined at a predetermined angle with respect to a short direction of the light source. 4. The film thickness at the end of the light emitting layer of each of the light source pieces is
The light source of the image reading device according to claim 1, wherein the light source is thinner than a central film thickness. 5. The image according to claim 1, wherein the light emitting layer of the light source piece comprises a central light emitting layer that emits light at the center of the light emitting layer, and an end light emitting layer that emits light at the end of the light emitting layer. Light source for reader. 6. The light source of the image reading device according to claim 5, wherein a thickness of the end light emitting layer is smaller than a thickness of the center light emitting layer. 7. A light emission control means for controlling a voltage applied to said edge light emitting layer and said central light emitting layer.
3. The light source of the image reading device according to 1. 8. The light source piece according to claim 1, wherein the light source piece is substantially L-shaped.
3. The light source of the image reading device according to 1. 9. The light source of the image reading apparatus according to claim 8, wherein an end face in a longitudinal direction of the light source piece is eccentric from a central portion in a short direction of the light source piece. 10. The light source of the image reading device according to claim 1, wherein the light emitting layer is made of electroluminescence. 11. A light source formed by joining a plurality of light source pieces is disposed on the left and right with respect to the lens, and the joined portions of the light source pieces disposed on the left and right are located at different positions in the longitudinal direction of the lens. A light source for an image reading apparatus, characterized in that the light source is formed. 12. An image reading apparatus using a light source that forms a light emitting layer on a transparent substrate and emits light by applying a voltage from both sides of the light emitting layer, wherein the light emitting layer is formed on a transparent substrate shorter than the entire length of the light source. An image reading apparatus using a light source obtained by joining a plurality of light source pieces formed in a longitudinal direction. 13. The image reading apparatus according to claim 12, wherein a width of an end portion of the light emitting layer of the light source piece is wider than a width of a central portion. 14. The image reading apparatus according to claim 12, wherein an end face in a longitudinal direction of the light source piece is inclined at a predetermined angle with respect to a lateral direction of the light source. 15. The image reading apparatus according to claim 12, wherein a thickness of an end portion of the light emitting layer of each light source piece is smaller than a thickness of a central portion. 16. The light emitting layer according to claim 12, wherein the light emitting layer of each light source piece comprises a central light emitting layer that emits light at the center of the light emitting layer, and an edge light emitting layer that emits light at an end of the light emitting layer. Image reading device. 17. The image reading device according to claim 16, wherein the thickness of the edge light emitting layer is smaller than that of the central light emitting layer. 18. The image reading apparatus according to claim 16, further comprising light emission control means for controlling a voltage applied to said edge light emitting layer and said central light emitting layer. 19. The image reading apparatus according to claim 12, wherein said light source piece is substantially L-shaped. 20. The image reading apparatus according to claim 19, wherein an end face in a longitudinal direction of the light source piece is eccentric from a central portion in a short direction of the light source piece. 21. The image reading device according to claim 12, wherein the light emitting layer is made of electroluminescence. 22. A light source formed by splicing a plurality of light source pieces is disposed on the left and right with respect to the lens, and the joint portions of the light source pieces disposed on the left and right are located at different positions in the longitudinal direction of the lens. An image reading device formed on a substrate.