JP3807494B2 - Light source and image reading apparatus using the light source - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light source, and more particularly to a light source of an image reading apparatus and an image reading apparatus using the light source.
[0002]
[Prior art]
A copying machine using an image reading device, a printer, a facsimile, or a multifunction printer having the functions of a facsimile, a copying machine, and a printer is drawn on a sheet or sheet-like recording medium (hereinafter referred to as a manuscript). An image reading device for reading an image such as the shape of a character / design is provided.
[0003]
As a light source of the image reading apparatus, a reduction optical method (reduction CCD method) has been well known in the past, but this configuration can obtain a sufficient light emission luminance, and a document surface can be obtained by increasing the focal depth of the lens. Therefore, there is an advantage that a clear image can be obtained even when the original is lifted. However, since the size is increased, when considering further reduction in size and thickness, a close contact method is used in which information from an original is guided to the sensor at the same magnification as shown in FIG.
[0004]
That is, the LED array 112 as a light source is arranged symmetrically diagonally above and below the original surface, and the light irradiated on the original surface is received by the rod lens array 121 described below arranged at an intermediate upper position between the two LED arrays 112. It has become. For example, as shown in FIG. 18, the LED array 112 has a configuration in which a number of LED elements 125 are arranged on a substrate 124 in the main scanning direction. For example, as shown in FIG. 19, the rod lens array 121 corresponds to the length of the LED array 112 in a plurality of rows by adjoining a predetermined number of cylindrical rod lenses 122 having a predetermined length and a predetermined diameter. The lengths are arranged and sandwiched between the substrates 124.
[0005]
According to this configuration, the distance between the original surface 106 and the rod lens 122 can be reduced as compared with the reduction optical method (reduction CCD method), so that the entire apparatus can be considerably reduced. Further, by reducing the focal length of the rod lens 122, a thinner device can be expected. In order 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, flare light between the rod lenses 122, and the like. As a result, the MTF (modulation transfer function) value decreases. Therefore, the applicant of this application has proposed a rod (fiber) lens array configuration (described later) with less optical noise in Japanese Patent Application No. 2000-224156.
[0006]
Further, since the light sources used in the LED array 112 are a set of point light sources, the original surface is required unless a certain distance is maintained between the original surface 106 and the light source even if the LED array 112 is used. The uniformity of illuminance on 106 cannot be ensured. In this respect, there is a limit to proceeding to reduce the thickness and size of the close contact type apparatus using the LED array 112. Therefore, the applicant of the present application has proposed in Japanese Patent Application No. 2000-217561 using layered electroluminescence as a light emitting medium for the purpose of further thinning and miniaturization.
[0007]
For example, as shown in FIG. 20, a transparent electrode layer 102 is formed on a transparent substrate 101 such as a glass substrate or a transparent resin that is long in the scanning direction, and a light emitting layer 100 as a light emitting medium is formed on the back surface thereof. The 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 having a predetermined intensity can be obtained from the front surface of the transparent electrode 102. When a color image is desired, three types of light emitting layers that emit three types of RGB light are formed on the transparent substrate 101.
[0008]
The configuration of the image reading apparatus using the light source configured as described above is almost the same as the configuration using the LED array 112, as will be described later. The light source can be brought closer to the document. Furthermore, by reducing the diameter of each rod lens 122 constituting the rod lens array and shortening the focal length, it can be expected to form a thinner image reading apparatus. The light emitting layer 100 is not limited to vapor deposition used for general thin film formation, and may be formed by printing, coating, or the like.
[0009]
[Problems to be solved by the invention]
As described above, even with a light source using electroluminescence as a light emitting medium, the light emission luminance depends on the position, particularly the position in the longitudinal direction, due to various factors. As the factor, resistance of electrode layers (particularly transparent electrodes) and the like can be considered. That is, the emission luminance of the electroluminescence in the portion where the distance from the connection point P between the lead and the transparent electrode layer 102 or the lead and the metal electrode layer 103 is larger than the emission luminance in the vicinity of the connection point P. small.
[0010]
In addition, variation in the thickness of the electroluminescence is also considered as a factor depending on the position of the light emission luminance of the light source. This is because it is difficult to produce electroluminescence having a uniform thickness of a certain length or more.
[0011]
If the light emission luminance of the light source is not uniform, uniform illuminance cannot be obtained on the document surface 106, and the image density read by the sensor 108 depends on the position of the document.
[0012]
The present invention has been proposed in view of the above-described conventional circumstances, and an object thereof is to provide a light source for an image reading apparatus capable of obtaining uniform light emission luminance.
[0013]
[Means for Solving the Problems]
    The present invention employs the following means in order to achieve the above object.That is, in a light source that forms a light emitting layer on a transparent substrate and emits light by applying a voltage from the front and back of the light emitting layer, a plurality of light emitting in the same color in which the light emitting layer is formed on a transparent substrate shorter than the entire length of the light source The light source piece is joined to the light source in the longitudinal direction to the required length,
The light emitting surface in the vicinity of at least one longitudinal end of each light source piece in the plurality of light source pieces is configured to be narrower than the width of the other light emitting surface, and the vicinity of the end portion configured to be narrow in the adjacent light source pieces The light source of the image reading device is complemented and joined together with the light emitting surface.
[0014]
  A light emitting layer with a length that makes it easy to adjust the thickness of the light emitting layer (easy to make it uniform) was formed.pluralBy forming a light source using a light source piece, a light source with uniform light emission luminance can be obtained.
[0015]
  Since the light emitting layer is not laminated on the end surface of the light source piece as shown in FIG. 2, the light emission luminance of the light source formed by joining the light source pieces is significantly reduced at the joint portion. Therefore, the width of the light emitting layer near the seam of the light source piecesOr widenThen, the light emission luminance of the joint portion is compensated. Electroluminescence can be used as the light emitting layer.
[0016]
The light source described above can be applied to an image reading apparatus.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1A is a plan view showing a light source 5 for an image reading apparatus of the present invention, and 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, transparent electrode layers 53α, β,... Are formed on transparent substrate pieces 52α, β,..., Which are long in the scanning direction, such as a transparent resin, and a light emitting layer 51α as a light emitting medium is formed on the transparent electrode layers 53α, β,. ... Are formed, and metal electrode layers 54α, β,... Are formed on the light emitting layers 51α, β. In the present embodiment, electroluminescence is used as the material of the light emitting layers 51α, β,. Leads 10 are connected to the transparent electrode layer 53, and leads 11 are connected to the metal electrode layer 54.
[0018]
By the way, since the electroluminescence used above is easily affected by humidity, the sealing treatment is performed for the purpose of preventing moisture from entering the light source pieces 50α, 50β, and preventing physical damage to the electroluminescence. Is made. That is, the light source pieces 50α, 50β... Are created as follows.
[0019]
As shown in FIG. 2, first, the transparent electrode layer 53α, the light emitting layer 51α, and the metal electrode layer 54α as described above, in addition to the sealing processing portion 57α of 0.3 to 0.5 mm from the end surface 56 of the transparent substrate piece 52α. Are stacked. Next, an adhesive resin 58 such as an epoxy resin for sealing processing is applied to the sealing processing portion 57α. Finally, the sealing glass 59α is placed on the metal electrode layer 54α and the epoxy resin 58.
[0020]
The light source pieces 50α, 50β, etc. thus created are joined together in sequence with an adhesive or the like to form one light source 5. Therefore, the lengths of the light source pieces 50α, 50β,... In the longitudinal direction are formed so that the transparent electrode layers 53α, 53β,..., The metal electrode layers 54α, 54β, or the light emitting layers 51α, 51β,. By configuring it to the extent possible (by a method) (about 80 mm), the illuminance on the document surface placed at a predetermined distance from the light source 5 can be made uniform regardless of the length of the light source 5.
[0021]
(Embodiment 2)
The light emitting layers 51α, 51β,... Constituting the light source pieces 50α, 50β,... In FIG. 1A are rectangular, and the contact portions of the light source pieces 50α, 50β,. It is parallel to the direction. Therefore, when the light source pieces 50α, 50β,... Are joined, the vicinity of the end face 56 does not emit light because of the sealing processing portions 57α, 57β,. Therefore, the light emission luminance of the light source 5 that joins the light source pieces 50α, 50β,... In this way becomes almost zero in the sealing processing portions 57α, 57β,. Therefore, in the present embodiment, the attenuation of the emission luminance is compensated as follows.
[0022]
FIG. 3 shows the present embodiment. The width of the light emitting layer 51 within 10 mm from the end portion 56 of each light source piece 50α, 50β... Is wider than the width of other portions.
[0023]
As a result, the width of the light emitting layers 51α, 51β... Is small at the center of the light source pieces 50α, 50β. Will be able to.
[0024]
(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 configured to have a certain angle with respect to the short direction of the transparent substrate piece 52, the above-described drawbacks are alleviated. That is, as shown in FIG. 4, the shape of 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 overlap in the short direction. With this configuration, the sealing processing portions 57α and 57β of the light emitting layers 51α and 51β are spread and distributed in the longitudinal direction, and the sealing processing portion 57 can be prevented from concentrating on a specific portion. .
It should be noted that the light emitting layer 51α of the light source piece 50α includes the light source piece 50β so that the light emission luminance of the light source 5 obtained by joining the parallelogram light source pieces 50α, 50β,. The length Q overlapping the light emitting layer 51β of the light emitting layer 51β is preferably 5 times or more the distance I (the length of the missing portion 40) I between the light emitting layers 51α and 51β. Further, it is desirable that the width W of the light emitting layers 1α and 1β is 1.7 times or less of the overlapping length Q.
[0025]
Moreover, as shown in FIG. 5, it is good also as a structure which made the light source piece 50 substantially L-shaped. 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 the other portions. By increasing the width of the light source 5, the width of the light emitting layer 51 of the overlap portion J can be increased.
[0026]
In the configuration shown in FIG. 5, in order to obtain a light source whose light emission luminance does not depend on the position in the longitudinal direction, the length M in the longitudinal direction of the light source 5 where the light emitting layer 51α and the light emitting layer 51β overlap is set as the light emitting layers 51α and 51β. It is desirable that the distance K be 5 times or more.
[0027]
Further, in order to reduce a decrease in the light emission luminance at the joint portion, for example, as shown in FIG. 5, the missing portion 40 of the light emitting layer 51 formed at the joint portion of the light source pieces 50α, 50β. It is desirable to adopt a configuration that is eccentric from the center in the short direction. When the missing portion 40 is decentered, it is desirable that the width S of the convex portion formed at one end of the light source pieces 50α, 50β... Be set to one third or more of the width W of the light emitting layer 51.
[0028]
(Embodiment 4)
The light emission luminance of the light source pieces 50α, 50β... Also changes depending on the electric field strength of the light emitting layers 51α, 51β. That is, when the thickness of the light emitting layer 51 is thin under the same interelectrode potential, the electric field strength increases and the light emission luminance of the light emitting layers 51α, 51β,. Therefore, as shown in FIG. 6, the object of the present invention can be achieved if the thickness of the light emitting layer 1 within 10 mm from the end face 56 is made thinner than the thickness of the central portion.
[0029]
(Embodiment 5)
Further, in order to compensate for the light emission luminance at the joint portion, as shown in FIG. 7, the light emitting layer 51 may be constituted by the end light emitting layer 22 and the central light emitting layer 21 made of electroluminescence material. good.
For example, the transparent electrode layer 32 of the end light emitting layer 22 is laminated within 5 mm from the sealing processing portion 57 of the transparent substrate piece 52, the end light emitting layer 22 is laminated thereon, and the end portion is further formed thereon. The metal electrode layer 42 of the light emitting layer 22 is laminated. Further, the transparent electrode layer 31 of the central light emitting layer 21 is laminated inside the end light emitting layer 22, the central light emitting layer 21 is laminated thereon, and the central light emitting layer 21 is further formed thereon. A metal electrode layer 41 is laminated. 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, 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 in order to obtain a constant light emission luminance at the seam portion is connected to the end portions via the leads 10 and 11. A larger voltage is applied between the transparent electrode layer 32 of the light emitting layer 22 and the metal electrode layer 42 than between the transparent electrode layer 31 of the central light emitting layer 21 and the metal electrode layer 41. Thereby, the light emission luminance of the end light emitting layer 22 is increased, and the light emission luminance of the light source 5 does not depend on the position in the longitudinal direction by forming the light source 5 by joining such light source pieces 50 together.
Furthermore, in order to obtain the light source 5 that emits light with uniform brightness with respect to the position in the longitudinal direction, the end light emitting layer 22 may be configured to be thinner than the central light emitting layer 21.
(Embodiment 6)
The light source 5 configured as described above can be used as the light sources 5a and 5b of the light source unit 15 of the image reading apparatus as shown in FIG. 8, for example. The light sources 5a and 5b are arranged symmetrically and obliquely above the document reading position Pa. Further, a fiber lens 14 to be described later is disposed above the reading position Pa in the vertical direction.
[0030]
In this configuration, since the light sources 5a and 5b are surface emitting, the illuminance on the reading position Pa does not depend on the position in the longitudinal direction of the light sources 5a and 5b even if the light source is brought close to the reading position Pa. By bringing the light sources 5a and 5b close to the reading position Pa, the light source unit 15 including the light sources 5a and 5b and the fiber lens 14 can be downsized. Further, by reducing the size of the light source unit 15, the entire image reading apparatus can be reduced.
[0031]
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. Even if the distance between the central portion O of the light sources 5a and 5b and the reading position Pa is reduced to 1 mm, uniform illuminance can be obtained. When the LED array 112 (FIG. 18) is used for the light sources 5a and 5b of the light source unit 15, if the distance between the central portion O of the LED element 125 and the reading position Pa is 7 mm or less, the uniform illuminance at the reading position Pa is I can't get it.
The light source 5 has a missing portion 40 at a joint portion of the light source pieces 50. In order to alleviate the decrease in light emission luminance due to the missing portion 40, when the light source 5 is used as the light sources 5a and 5b, the light source 5 is arranged as follows.
The missing portions 40 a and 40 b formed in the light sources 5 a and 5 b are arranged so as not to exist at the same position with respect to the longitudinal direction of the condenser lens 14. For example, as shown in FIG. 9A, the light source 5a is shifted from the light source 5b in the longitudinal direction of the condenser lens. For example, when the total length of the light sources 5a and 5b is 320 mm and the length of the missing portions 40a and 40b of the light sources 5a and 5b is 1 mm, the shifting distance is preferably 2 mm or more.
By arranging in this way, as compared with the case where the light sources 5a and 5b are arranged so that the missing portions 40a and 40b exist at the same position in the longitudinal direction of the condenser lens 14 as shown in FIG. The variation in illuminance at the reading position Pa due to the missing portions 40a and 40b is reduced.
FIGS. 9B and 10B show the illuminance distribution at the reading position Pa when the light source 5 is arranged as shown in FIGS. 9A and 10A.
[0032]
In addition, as a structure for arrange | positioning the missing parts 40a and 40b in the position away with respect to the longitudinal direction of the condensing lens 14, the following structures are also considered. That is, the light source piece 50 shorter than the other light source pieces 50 is used for the light source pieces 50 at both ends of the light source 5a or the light source 5b.
[0033]
(Embodiment 7)
In the configuration of FIG. 11, 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 is compared with the diameter of the conventional rod. It is necessary to decrease the distance or to increase the distance (conjugate length) between the document surface 6 and the sensor 8 shown in FIG. In the conventional rod lens 122, since there is a limit to the reduction in diameter, the conjugate length is increased and the depth of focus is kept deep. However, when the conjugate length is increased as described above, the image reading apparatus is reduced in thickness and size. It would be against the plan.
Therefore, as shown in FIG. 11, the fiber lens 14 is formed 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 reader can be reduced in thickness and size. Phenomena such as flare become noticeable. Therefore, as shown in FIG. 12, a light absorbing layer 143 is formed on the outer periphery of each optical fiber 140 having a predetermined length, or a plurality of optical fibers 140 having a predetermined length are formed as shown in FIG. A bundle of fibers and a fiber bundle 144 having a light absorption layer 141 formed on the outer periphery thereof are formed.
Here, 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 center axis Z of the optical fiber 140 and the incident light V. The opening angle ω is set so as to satisfy the relationship of being smaller than the tangent value of the opening angle ω that is the angle between them. The opening angle ω is the maximum angle at which light can be normally transmitted. FIG. 13 shows a state in which the light V is incident on the optical fiber 140 at the maximum angle at which light can be normally transmitted. In this figure, the center axis Z of the optical fiber 140 and the incident light are incident. The angle with the light V corresponds to the opening angle ω.
In this way, a plurality of optical fibers 140 each having the light absorption layer 143 or a plurality of fiber bundles 144 having the light absorption layer 141 are placed in a mold having a predetermined shape opened up and down. The length direction is filled up in parallel in the radial direction, and the adhesive is filled in the gaps between the optical fibers 140 to be solidified and deframed. The predetermined shape of the mold is a shape necessary for an image reading apparatus such as a copying machine using the fiber lens 14 to perform its original function, and is a belt shape having a length perpendicular to the normal document conveying direction. Become. Furthermore, as shown in FIG. 14, if necessary for molding, the optical fiber 140 alone or the fiber bundle 144 is sandwiched between the substrate 142 made of opaque glass or resin in the mold, and the substrate 142 and the light The single fibers 140 or the fiber bundles 144 may be bonded together by the above method.
[0034]
Further, a plurality of optical fibers 140 having the light absorption layer 143 formed therein or a plurality of fiber bundles 144 having the light absorption layer 141 are arranged in close contact with each other, for example, in parallel with the length direction of the optical fiber 140 in the radial direction. There is a method (not shown) in which the adhesive is solidified by filling the gap with an adhesive, sandwiching it between two opaque glass or resin substrates 142 having a predetermined shape, and thermocompression bonding.
[0035]
The optical fiber 140 has a refractive index that gradually decreases toward the outer periphery in a direction perpendicular to the axis, and in principle, the light converges in the central direction without the light absorbing layers 141 and 143. However, when the diameter is reduced as an actual problem, the crosstalk or flare phenomenon becomes remarkable, and the light absorption layers 141 and 143 need to be formed.
[0036]
The light absorption layers 141 and 143 can be formed by coating, dipping, or vapor-depositing a black resin. Further, the adhesive used in a state where the optical fiber 140 alone or the fiber bundle 144 is filled in the mold may be a conventional adhesive, but an adhesive such as black that can prevent the crosstalk or flare phenomenon. Is preferably used, and these adhesives serve as the light absorption layer 141. Here, when the black or the like adhesive is also used as a light absorbing layer, the adhesive is formed on the outer periphery of the optical fiber 140 or the fiber bundle 144, and the upper and lower sides are opened as described above. The fiber lens 14 is manufactured by a method using a mold having a predetermined shape or a method of sandwiching between two substrates 142 and thermocompression bonding. Of course, in this manufacture, the adhesive such as black is spread over the entire outer periphery of the optical fiber 140 or the fiber bundle 144. As the adhesive, for example, glass or resin having a low softening point can be used, but the softening point needs to be lower than the material of the optical fiber 140 and the substrate 142 constituting the fiber lens 14. It is.
[0037]
Here, the diameter of the optical fiber 140 included in the fiber lens 14 is about 0.1 mm, which is 1/6 of the diameter of the conventional rod lens, and the length of the optical fiber 140 is the length of the rod lens. When the thickness is approximately 4.0 mm, which is 1/6 of the thickness, the reading devices 120a and 120b shown in FIG. 6 is about 10 mm.
[0038]
FIG. 15 shows an image reading apparatus to which the present invention is applied. In this case, both the front and back surfaces can be read. Of course, this image reading apparatus may be used for a fax machine or a copier.
[0039]
As in the prior art, the document 9 drawn into the apparatus by the pick roller 151 constituting the document transport unit 162 is fed into the horizontal transport path 133 by the upper and lower feed rollers 152a and 152b. The conveyance path 133 is provided with 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, and is controlled to operate when the leading end of the document 9 reaches a predetermined position. It has become.
[0040]
Two upper and lower reading devices 120a and 120b are arranged near the front end of the horizontal conveyance path 133, and both sides of the original 9 are simultaneously read at the upper and lower reading positions Pa and Pb when the original 9 is conveyed.
[0041]
Here, the lower reading device 120b is required to have a deep depth of focus in order to read a document that floats from the document surface 136, for example, a book in a spread state. Therefore, by using the fiber lens 14 shown in FIG. 11 and the light source 5 of the present invention for the lower reading device 120b, the entire reading device 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 in the reading devices 120a and 120b on both the upper and lower sides, the image reading device can be further reduced in thickness.
[0042]
As described above, when images on both sides of the document 9 are read, if the irradiation light from the light sources of the upper and lower reading devices 120a and 120b irradiates the same position in the upper and lower sides, the mutual irradiation light interferes. It will be. Therefore, the arrangement of the reading devices 120a and 120b is shifted to such an extent that the light emitted from the light sources of the reading devices 120a and 120b is not at the same position in the vertical direction, thereby preventing the interference.
[0043]
The reading devices 120a and 120b have reading characteristics such as a γ value (density vs. sensor output value) and gradation characteristics that affect reading information obtained by reading images on both sides of the document 9. Here, it is desirable that the print quality of the images printed on both sides of the paper or the like provided in the copying machine is the same. For that purpose, the reading information from the upper reading device 120a and the reading information from the lower reading device 120b are used. The read information must be the same. Therefore, the copying machine is provided with a reading correction unit 132 and is configured to correct the reading characteristics of the reading devices 120a and 120b to be the same.
[0044]
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 expressed as γ> 1 and γ as shown in FIG. = 1 or γ <1. Here, when the sensor output is increased with an arbitrary light amount value a, the reading correction means 132 corrects the γ value so that γ> 1. Similarly, the reading correction unit 132 performs correction so that γ = 1 or γ <1 to adjust the light amount and the sensor output value, and the reading information of the reading devices 120a and 120b on the upper and lower sides is made the same. To do.
[0045]
In addition, the upper reading device 120a may be fixed and the lower reading device 120b may be movable among the upper and lower reading devices 120a and 120b provided in the copying machine. For example, a reduction optical system ( A moving type using a reduction CCD method may be used.
[0046]
In the image reading operation in this case, first, the original 9 inserted in the original conveying section 162 is conveyed to the conveying section 133 by the pick roller 151 and the feeding rollers 152a and 152b. As a result, the document 9 is fed into the horizontal conveyance path 133 while being read by the fixed reading device 120a, and a reading table (not shown) made of glass is disposed below the conveyance path 133. In the state where the document 9 is placed on the reading table, the belt roller 164 temporarily stops, and the fluorescent lamp (that is, the reading position Pb) that is 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.
[0047]
As described above, the lower reading device 120b is a movable type using a reduction optical method (reduction CCD method), and is the same as that of a current copier capable of placing the original 9 on the glass original platen from above. By adopting the configuration, it is possible to deal with a document that cannot be fed by the document conveyance unit 162 such as a book.
[0048]
Of course, instead of moving the lower reading device 120b using the reduction optical method (reduction CCD method) as described above, the fluorescent lamp is fixed at a predetermined position, and the document 9 conveyed by the belt roller 164 is fixed. A corresponding reading configuration is also possible.
[0049]
The above is a case where the image reading apparatus using the light source of 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]
1A and 1B are 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 the 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 composed of a substantially L-shaped light source piece.
FIG. 6 is a cross-sectional view of a light source piece having a thin film thickness of an electroluminescence layer near an end face.
FIG. 7 is a configuration diagram illustrating a light source piece including a central light emitting layer and an end 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 illustrating 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 provided in the image reading apparatus.
FIG. 12 is a perspective view of another fiber lens provided in the image reading apparatus.
FIG. 13 is a perspective view of an optical fiber constituting a fiber lens.
FIG. 14 is a cross-sectional view of the fiber lens taken along line XX ′.
FIG. 15 is a configuration diagram of a copying machine that performs duplex reading.
FIG. 16 is a diagram illustrating an example of correction by a γ value of a reading correction unit.
FIG. 17 is a configuration diagram of a conventional contact-type image reading apparatus.
FIG. 18 is a perspective view of a light source provided in a conventional contact-type image reading apparatus.
FIG. 19 is a perspective view of a rod lens array provided in a conventional contact-type 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

Claims (14)

In a light source that forms a light emitting layer on a transparent substrate and emits light by applying a voltage from the front and back of the light emitting layer,
A plurality of light source pieces that emit light of the same color, in which the light emitting layer is formed on a transparent substrate shorter than the entire length of the light source, are spliced in the longitudinal direction of the light source to a required length,
The light emitting surface in the vicinity of at least one longitudinal end of each light source piece in the plurality of light source pieces is configured to be narrower than the width of the other light emitting surface, and the end portion configured to be narrow in the adjacent light source pieces A light source for an image reading apparatus, wherein the light source is spliced in a complementary manner with a nearby light emitting surface .   In the plurality of light source pieces, the light emitting surface in the vicinity of at least one longitudinal end of each light source piece is configured to have an acute angle, and the vicinity of the end configured to have an acute angle of an adjacent light source piece The light source of the image reading device according to claim 1, wherein the light source is joined together in a complementary manner.   The light emitting surface in the vicinity of at least one longitudinal end portion of each light source piece in the plurality of light source pieces is configured in a substantially L shape, and in the vicinity of the end portion configured in a substantially L shape of the adjacent light source pieces. The light source of the image reading device according to claim 1, wherein the light source is joined together in a complementary manner.   2. The image reading device according to claim 1, wherein a width in a short direction of the light emitting surfaces at the end portions that are joined together is equal to or greater than a width in a short direction of the light emitting surfaces that are not joined together. The light source of the device.   The light source of the image reading apparatus according to claim 1, wherein the light emitting layer is made of electroluminescence. In a light source that forms a light emitting layer on a transparent substrate and emits light by applying a voltage from the front and back of the light emitting layer,
A light source piece in which the light emitting layer is formed on a transparent substrate shorter than the entire length of the light source is joined to a plurality of longitudinal directions to obtain a required length, and the longitudinal end surface of the light source piece is substantially L-shaped. The light source of the image reading device is eccentric from the center in the short direction. A light source formed by joining a plurality of light source pieces in a row is arranged in a row on the left and right with respect to the lens, and the joined portions of the light source pieces arranged in a row on the left and right are different in the longitudinal direction of the lens. A light source for an image reading apparatus, wherein the light source is formed at a position. In 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 the front and back of the light emitting layer,
A plurality of light source pieces that emit light of the same color, in which the light emitting layer is formed on a transparent substrate shorter than the entire length of the light source, are spliced in the longitudinal direction of the light source to a required length,
The light emitting surface in the vicinity of at least one longitudinal end of each light source piece in the plurality of light source pieces is configured to be narrower than the width of the other light emitting surface, and the end portion configured to be narrow in the adjacent light source pieces An image reading apparatus characterized in that it is spliced in a complementary manner with a nearby light emitting surface .   In the plurality of light source pieces, the light emitting surface in the vicinity of at least one longitudinal end of each light source piece is configured to have an acute angle, and the vicinity of the end configured to have an acute angle of an adjacent light source piece The image reading apparatus according to claim 8, wherein the image reading apparatus is spliced together in a complementary manner with the light emitting surface of the image forming apparatus.   The light emitting surface in the vicinity of at least one longitudinal end portion of each light source piece in the plurality of light source pieces is configured in a substantially L shape, and in the vicinity of the end portion configured in a substantially L shape of the adjacent light source pieces. The image reading apparatus according to claim 8, wherein the image reading apparatus is spliced together in a complementary manner with the light emitting surface of the image forming apparatus.   9. The image reading device according to claim 8, wherein the width of the light emitting surfaces at the end portions that are joined together is equal to or greater than the width of the light emitting surfaces that are not joined together in the short direction. apparatus.   The image reading apparatus according to claim 8, wherein the light emitting layer is made of electroluminescence. In 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 the front and back of the light emitting layer,
A light source piece in which the light emitting layer is formed on a transparent substrate shorter than the entire length of the light source is joined to a plurality of longitudinal directions to obtain a required length, and the longitudinal end surface of the light source piece is substantially L-shaped. Reading device eccentric from the center in the short direction A light source formed by joining a plurality of light source pieces in a row is arranged in a row on the left and right with respect to the lens, and the joined portions of the light source pieces arranged in a row on the left and right are different in the longitudinal direction of the lens. An image reading apparatus formed at a position.

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