JP2011250315A - Contact image reading sensor and contact image reading apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read an image while preventing image degradation.SOLUTION: A contact image reading sensor 10 includes: a light receiving layer 15 that has a plurality of two-dimensionally arranged light receiving elements 16; a light transmissive protecting sheet layer 25 disposed on a surface of a side of the light receiving layer 15 where the light receiving elements 16 receive light; and a surface light source 20 that, when emitting light, increases components of the emitted light in a thickness direction of the protecting sheet layer 25 compared to diffused light and sends the emitted light from among the light receiving elements 16 in the light receiving layer 15 in a direction toward the protecting sheet layer 25. When an image is to be read with reflected light from an original 40, the configuration prevents the light from the surface light source 20 from being reflected by a protecting sheet interface 26 and received by the light receiving elements 16 before being reflected by the original 40, thereby preventing the otherwise resulting increase in noise content in reading an image of the original 40. Thus, the contact image reading sensor 10 reads an image while preventing image degradation.

Description

  The present invention relates to a contact image reading apparatus.

  The image reading apparatus includes a light receiving element that converts detected light into an electric signal. The light reflected by the original that reads the image is detected by the light receiving element and converted into an electric signal, so that the image of the original is electrically converted. Is processed. The image reading apparatus reads an image of a document based on the light detected by the light receiving element as described above. However, some conventional image reading apparatuses correct a signal received by the light received by the light receiving element and read the document. Some have improved the accuracy.

  For example, in the image reading apparatus described in Patent Document 1, a monochrome reference plate for monochrome level correction is provided at the end of a fiber array plate in contact with an image sensor element, and a signal by light received by the image sensor element is received. The black and white reference plate is used for correction. In the image reading apparatus described in Patent Document 2, a standard plate is provided on the pressure plate to be pressed against the original, and a signal generated by light received by the CCD is corrected based on reflected light reflected by the standard plate. In the image reading apparatus described in Patent Document 3, a white reference plate is provided on the side of the document pressing member facing the two-dimensional reading sensor, and the white reference plate is read by the two-dimensional reading sensor, so that the correction data for shading is obtained. Have acquired. In the image reading apparatuses described in Patent Documents 1 to 3, due to these corrections and actions, a change over time when reading an image of a document by receiving light reflected by the document with a light receiving element such as an image sensor element. The deterioration of reading accuracy due to the above is suppressed.

JP 2001-94722 A JP 2007-43468 A JP 2009-296092 A

  The image reading apparatus reads an image of a document based on the light detected by the light receiving element as described above. However, in recent image reading apparatuses, the configuration is simplified in order to reduce the size of the apparatus. When reading, there is a contact-type image reading apparatus that reads a document by contacting the contact-type image reading sensor that is an image reading portion. As described above, when a document is brought into close contact with the contact-type image reading sensor, it is difficult to irradiate the document with light reflected from the document from the outside. A light source is provided to the light source, and the light emitted from the light source is transmitted through the contact-type image reading sensor to reach the document and reflected by the document.

  Specifically, the contact-type image reading sensor is provided with a plurality of light receiving elements, thereby receiving light reflected from the document and reading an image of the document. The plurality of light receiving elements provided in this manner have a predetermined interval. Open and arranged. For this reason, the light emitted from the light source disposed on the opposite side of the contact-type image reading sensor to the side where the document is brought into contact, that is, the light emitted from the light source disposed on the back surface of the contact-type image reading sensor is received. The light passes through the elements in the direction of the original, reflects off the original, and moves toward the contact image reading sensor. The contact-type image reading sensor reads an image of a document by receiving this light with a light receiving element.

  Further, in such a contact-type image reading apparatus, since the document is brought into direct contact with the contact-type image reading sensor, it is possible to prevent the light-receiving element included in the contact-type image reading sensor from being stained or scratched. For this reason, a protective sheet is often provided on the surface of the contact-type image reading sensor on the side where the document is brought into close contact. This protective sheet is formed of a member such as a transparent resin or glass, and transmits light directed between the light receiving elements in the contact image reading sensor toward the document, or is reflected by the document to be a contact image. For example, light directed toward the reading sensor can be transmitted.

  However, the light emitted from the light source to the document usually contains various components, and this light is diffused light. For this reason, even if it is irradiated with a light source and enters the protective sheet through the light receiving elements, it enters as diffused light, but if the light from the light source enters obliquely with respect to the protective sheet formation direction, Some may be reflected by the inner surface of the protective sheet. In other words, since the refractive index of the protective sheet and the air around the protective sheet is different, the traveling direction of light traveling inside the protective sheet is inclined with respect to the interface between the protective sheet and air. This light may be reflected at the interface. When the light passing through the inside of the protective sheet is thus reflected at the interface between the protective sheet and air, this light is directed toward the light receiving element when reflected at the interface before being reflected by the original.

  For this reason, the light receiving element receives not only the light reflected by the original document but also the light reflected by the interface between the protective sheet and the air, and the light reflected by the interface receives the light reflected by the original document. Appears as a noise component when reading an image. Therefore, when an image of a document is read by light emitted from a light source disposed on the back surface of the contact image reading sensor, noise increases due to light reflected at the interface between the protective sheet and air, so that the read image In some cases, the image quality deteriorated.

  The present invention has been made in view of the above, and an object of the present invention is to provide a contact image reading sensor and a contact image reading apparatus capable of reading an image while suppressing deterioration in image quality.

  In order to solve the above-described problems and achieve the object, a contact image reading sensor according to the present invention includes a light receiving layer having a plurality of light receiving elements arranged in a two-dimensional array, and light reception by the light receiving elements in the light receiving layer. A protective sheet layer that transmits light and a light source that emits light; and a light component in the thickness direction of the protective sheet layer as compared with diffused light. And an illuminating unit that irradiates light emitted from the light source in a direction from the light receiving element in the light receiving layer toward the protective sheet layer.

  In the present invention, the light applied to the original when the image is read by the reflected light from the original is increased in light component in the thickness direction of the protective sheet layer compared to the diffused light, so Since the illumination part irradiates in the direction of the protective sheet layer, the noise component can be reduced and read. That is, the light directed toward the original through the protective sheet layer when reading the image of the original is irradiated in a direction substantially perpendicular to the surface of the protective sheet layer where the light exits from the protective sheet layer. For this reason, when the light traveling in the direction of the original in the protective sheet layer is emitted from the protective sheet layer, the light is not reflected at the inner portion of this surface, that is, at the interface between the protective sheet layer and the air. The light is emitted from the sheet layer. As described above, the light emitted from the protective sheet layer is reflected by the original, becomes reflected light, is reflected in the direction in which the light is directed, passes through the protective sheet layer, and travels toward the light receiving layer. Thereby, the light reflected from the original is received by the light receiving element of the light receiving layer, and the image of the original is read.

  In addition, since the light emitted from the illumination unit in the direction of the original when reading the image of the original increases the light component in the thickness direction of the protective sheet layer, this light is emitted from the interface between the protective sheet layer and air. It is difficult to reflect. For this reason, this light is reflected at the interface between the protective sheet layer and the air before being reflected by the document, and the light reflected by the interface is received by the light receiving element. It can suppress that a component increases. Therefore, it is possible to suppress deterioration in image quality due to an increase in noise components when reading an image. As a result, it is possible to read an image while suppressing deterioration in image quality.

  In the contact image reading sensor, it is preferable that the illumination unit emits light so that light passing through the inside of the protective sheet layer increases a component in a thickness direction of the protective sheet layer.

  In this invention, the light passing through the inside of the protective sheet layer is irradiated by the illuminating unit so that the component in the thickness direction of the protective sheet layer is increased. It is possible to more reliably suppress reflection at the interface between the protective sheet layer and air when the document is emitted from the side to the side where the document is located. Thereby, it can suppress more reliably that the noise component at the time of the image reading resulting from having received the light reflected in the interface of a protective sheet layer and air with a light receiving element is increased. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In the contact image reading sensor, it is preferable that the light source emits only substantially parallel light.

  In the present invention, since the light source of the illumination unit emits only substantially parallel light, it is possible to transmit the protective sheet layer without diffusing the light when reading the image of the document. For this reason, as for the light reaching the interface between the protective sheet layer and the air, almost all of the light reaches the interface at the same angle, and almost all of the light reaches in the direction orthogonal to the interface. Thereby, it can suppress more reliably that the light which permeate | transmits a protective sheet layer reflects in an interface, and can suppress more reliably the increase in the noise component at the time of image reading. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In the contact-type image reading sensor, it is preferable that an LED light source having a high directivity arranged in a planar shape is used as the light source.

  In the present invention, since the LED light source having such high directivity is used as the light source of the illumination unit, the light irradiated in the direction of the document when reading the image of the document can be irradiated without being diffused. As a result, almost all of the light reaching the interface between the protective sheet layer and air can be made to reach the interface at the same angle, and almost all of the light can be made to reach in the direction orthogonal to the interface. Can do. Therefore, it can suppress more reliably that the light which permeate | transmits a protective sheet layer reflects in an interface, and can suppress more reliably the increase in the noise component at the time of image reading. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In the contact image reading sensor, a surface emitting laser array is preferably used as the light source.

  In this invention, since a surface emitting laser array is used as the light source of the illumination unit, the light component in the thickness direction of the protective sheet layer is increased compared with the diffused light, and the light is directed in the direction of the protective sheet layer. When providing the illumination part to irradiate, it can provide easily. Thereby, before the light from the illuminating part is reflected by the document, it can be easily suppressed from being reflected at the interface between the protective sheet layer and the air, and due to the reflection of the light at this interface, It is possible to easily suppress degradation of image quality when reading an image of a document. As a result, an image can be read more easily while suppressing deterioration in image quality.

  In the contact-type image reading sensor, the illumination unit includes a parallel light generation unit that converts light emitted from the light source into substantially parallel light, and the light emitted from the light source is substantially omitted from the parallel light generation unit. It is preferable to irradiate the parallel light in the direction of the protective sheet layer.

  In the present invention, since the illumination unit is provided with the parallel light generation unit that converts the light emitted from the light source into substantially parallel light, the protective sheet more reliably compares the light used for reading the image of the document with the diffused light. The light component in the thickness direction of the layer can be increased, and light can be irradiated in the direction of the protective sheet layer. Moreover, when providing the illumination part which irradiates such light, it can provide easily by using a parallel light production | generation part. Accordingly, it is possible to more reliably and easily suppress deterioration of image quality when reading an image of a document due to light reflected from the illumination unit being reflected at the interface between the protective sheet layer and air. Can do. As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  In the contact image reading sensor, a prism sheet is preferably used for the parallel light generation unit.

  In the present invention, since the prism sheet is used as the parallel light generation unit, when the light emitted from the light source is irradiated in the direction of the protective sheet layer, the prism sheet makes the parallel light more reliably and easily. Can be irradiated. Thereby, it is more reliably and easily suppressed that the image quality is deteriorated at the time of reading the image of the document due to the light from the illumination unit being reflected at the interface between the protective sheet layer and the air. be able to. As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  In the contact image reading sensor, it is preferable that a collimating lens is used for the parallel light generation unit.

  In this invention, since the collimating lens is used as the parallel light generation unit, when irradiating the light emitted from the light source in the direction of the protective sheet layer, it is more surely and easily made substantially parallel light. Can do. Thereby, it can suppress more reliably and easily that the light which permeate | transmits the inside of a protective sheet layer reflects in the interface of a protective sheet layer and air. As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  In the contact image reading sensor, a slit plate is preferably used for the parallel light generation unit.

  In this invention, since the slit plate is used as the parallel light generating part, when irradiating the light emitted from the light source in the direction of the protective sheet layer, it is more surely and easily irradiated as substantially parallel light. Can do. Thereby, it can suppress more reliably and easily that the light which permeate | transmits the inside of a protective sheet layer reflects in the interface of a protective sheet layer and air. As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  In the contact-type image reading sensor, the illumination unit includes a polarizing filter, and the light emitted from the light source is converted into a component of only a p-wave using the polarizing filter in the direction of the protective sheet layer. Irradiation is preferred.

  In this invention, the light emitted from the light source is irradiated in the direction of the protective sheet layer using a polarizing filter as a p-wave only component, so that the light transmitted through the protective sheet layer is between the protective sheet layer and the air. It is possible to more reliably suppress reflection at the interface. In other words, when light is transmitted through the interface between objects having different refractive indexes, the reflectance of light at this interface is a p-wave whose light wave amplitude direction is parallel to the interface, and light. The s wave has a higher reflectivity when the light reaches the interface at the same angle than the p wave. ing.

  For this reason, a polarizing filter is provided in the illumination unit, and the light transmitted from the protective sheet layer is protected by polarizing the light emitted from the light source with the polarizing filter and irradiating only the p-wave component in the direction of the protective sheet layer. When reaching the interface between the sheet layer and the air, reflection at the interface can be made difficult. Therefore, the light component irradiated in the direction of the protective sheet layer by the illumination unit receives the light reflected at the interface between the protective sheet layer and the air by the light receiving element, so that a noise component at the time of image reading increases. This can be more reliably suppressed. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In the contact image reading sensor, the protective sheet layer is preferably an optical member and has a high transmittance.

  In this invention, since the protective sheet layer is provided by an optical member having a high transmittance, it is possible to suppress diffusion of this light in the protective sheet layer when the protective sheet layer is irradiated with light from the illumination part. it can. As a result, the light emitted from the illumination unit diffuses in the protective sheet layer before reaching the document, and the diffused light is received by the light receiving element of the light receiving layer toward the light receiving layer. Thus, it is possible to suppress an increase in noise components during image reading. Therefore, the light receiving element not only suppresses unnecessary light reception due to reflection at the interface between the protective sheet layer and the air, but also diffuses light within the protective sheet layer, thereby causing the light receiving element to be ineffective. Receiving necessary light can also be suppressed, and increase in noise components can be suppressed more reliably. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In the contact image reading sensor, the protective sheet layer is preferably formed of an optical member having a small thickness.

  In this invention, since the protective sheet layer is provided by a thin optical member, it is possible to reduce diffused light in the protective sheet layer when the protective sheet layer is irradiated with light from the illumination part. That is, when light is transmitted through the protective sheet layer, this light may diffuse in the protective sheet layer. However, by reducing the thickness of the protective sheet layer, the distance of the light passing through the protective sheet layer is shortened. can do. Thereby, the opportunity for light to diffuse in the protective sheet layer can be reduced, and the diffused light in the protective sheet layer can be reduced. Accordingly, since the light receiving element of the light receiving layer receives the diffused light in the protective sheet layer, the light receiving element can be prevented from receiving unnecessary light, and thus the noise component is increased more reliably. This can be suppressed. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In the contact image reading sensor, the protective sheet layer is preferably formed of an insulating member.

  In this invention, since the protective sheet layer is formed of the insulating member, the light receiving element can be electrically protected. For example, even when a document that comes into contact with the contact image reading sensor is charged, by forming the protective sheet layer with an insulating member, it is possible to suppress static electricity from being generated between the document and the light receiving element. Can be electrically protected. Therefore, when protecting the light receiving element, which is a part for reading the image of the document, with the protective sheet layer, it is not only protected from dust or from being damaged, but also electrically protected, and the light receiving element It is possible to suppress damage to the light receiving element due to unnecessary electricity flowing in the device. As a result, an image can be read more stably.

  In the contact image reading sensor, the protective sheet layer is preferably formed of a member having a refractive index between the refractive index of air and the refractive index of glass.

  In this invention, since the protective sheet layer is formed by a member having a refractive index between the refractive index of air and the refractive index of glass, the light transmitted through the protective sheet layer is reflected between the protective sheet layer and the air. It is possible to more reliably suppress reflection at the interface. That is, a light receiving layer having a light receiving element is often formed by disposing a light receiving element on glass, and a document whose image is read by a contact image reading sensor is a light receiving layer in a protective sheet layer. Place on the opposite side of. Further, when reading the image of the document, the light radiated from the illumination unit in the direction of the protective sheet layer is emitted from between the light receiving elements to the protective sheet layer. Head over. Further, when this light reaches the document, it passes through the interface between the protective sheet layer and air and reaches the document in the air. Accordingly, the light emitted from the light source of the illumination unit passes through the glass of the light receiving layer, passes through the protective sheet layer, and then exits into the air.

  For this reason, by forming the protective sheet layer with a member having a refractive index between the refractive index of air and the refractive index of glass, the light emitted from the light source of the illuminating unit is reflected in the thickness direction of the protective sheet layer. Even when a component in a direction having an angle with respect to the light is contained, the light is refracted by a difference in refractive index when entering the protective sheet layer from the glass. That is, when the light enters the protective sheet layer from the glass, the traveling direction changes due to the difference in refractive index, and the angle with respect to the thickness direction of the protective sheet layer becomes small. Therefore, even when the light emitted from the light source of the illumination unit includes a component in a direction having an angle with respect to the thickness direction of the protective sheet layer, this angle is reduced in the protective sheet layer due to the difference in refractive index. Since it becomes small, it becomes difficult to reflect this light at the interface between the protective sheet layer and the air. Thereby, it can suppress more reliably that the noise component at the time of the image reading resulting from the reflection in the interface of a protection sheet layer and air increases. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In order to solve the above-described problems and achieve the object, a contact image reading apparatus according to the present invention includes the contact image reading sensor and shading of an image of a document read by the contact image reading sensor. And a control unit that performs correction.

  Since the present invention has a control unit that performs shading correction of the original image read by the contact image reading sensor, noise during reading of the original image can be reduced, and further, shading correction can be performed. Can be performed appropriately. In other words, when light is irradiated from the illumination part in the direction of the protective sheet layer, this light is reflected at the interface between the protective sheet layer and air, and noise is generated due to the reflected light reaching the light receiving element. In this case, the data when the light source of the illumination unit is turned off cannot be used as the black-side correction data at the time of shading correction. In this case, it is necessary to prepare a black reference sheet to be used when obtaining black-side correction data. When obtaining data with such a sheet, if dust or the like adheres to the sheet, the state is corrected to the black side. Since it becomes data, the image after shading correction may be disturbed.

  In contrast, when light is irradiated from the illumination unit of the contact image reading sensor in the direction of the protective sheet layer, if the light is suppressed from being reflected at the interface between the protective sheet layer and the air, the image reading is performed. Since generation of noise at the time can be suppressed, a state in which the illumination unit is turned off can be used as black-side correction data. For this reason, when the shading correction is performed, the data when the light source of the illuminating unit is turned off can be used. Therefore, the correction data on the black side can be appropriately obtained, and the image quality of the image after the shading correction is ensured. Can do. As a result, it is possible to read an image while suppressing deterioration in image quality.

  Further, it is preferable that the contact image reading apparatus further includes a storage unit that stores reference data for performing the shading correction.

  In the present invention, since the storage unit stores the reference data at the time of shading correction, when performing the shading correction, the image data photographed by the contact image reading sensor is compared with the reference data, and the shading correction is performed. The correction data used for can be easily generated. Therefore, shading correction can be performed more easily, and the image quality of the image after shading correction can be ensured more reliably. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  Further, in the contact image reading apparatus, black reference data serving as a reference on a black side of an image read by the contact image reading sensor among the reference data is relative to a reading range of the contact image reading sensor. Preferably, the data is line data.

  In the present invention, since the black reference data at the time of shading correction is line data with respect to the reading range of the contact image reading sensor, the data amount of the black reference data can be reduced. As a result, the capacity of the storage unit for storing the reference data can be reduced, and since the amount of data is small, the amount of data handled during shading correction can be reduced, and shading correction can be performed more easily. it can. As a result, an image can be read more easily while suppressing deterioration in image quality.

  In the contact image reading apparatus, the black reference data serving as a reference on the black side of the image read by the contact image reading sensor among the reference data is common in the reading range of the contact image reading sensor. It is preferable that it is one data.

  In the present invention, since the black reference data at the time of shading correction is one common data in the reading range of the contact image reading sensor, the data amount of the black reference data can be further reduced. Thereby, since the amount of data to be processed is reduced, shading correction can be performed more easily. As a result, an image can be read more easily while suppressing deterioration in image quality.

  The contact-type image reading sensor and the contact-type image reading apparatus according to the present invention have an effect that an image can be read while suppressing deterioration in image quality.

FIG. 1 is a diagram illustrating an appearance of a contact image reading apparatus according to an embodiment, and is a diagram illustrating a state in which a lid is closed. FIG. 2 is a diagram illustrating a state in which the lid of the contact image reading apparatus illustrated in FIG. 1 is opened. FIG. 3 is a cross-sectional view showing the configuration of the image reading sensor shown in FIG. FIG. 4 is a diagram showing an outline of the configuration of the contact image reading apparatus shown in FIG. FIG. 5 is an explanatory diagram for reading an image of a document. 6 is a cross-sectional view taken along the line AA in FIG. 1 when reading an image of a document. FIG. 7 is an explanatory diagram of light emitted from the surface light source when reading an image of a document. FIG. 8 is an explanatory diagram when light passes through the protective sheet layer. FIG. 9 is an explanatory diagram showing the relationship between the incident angle of light and the reflectance when the refractive index of the protective sheet layer is 1.4. FIG. 10 is an explanatory diagram showing the relationship between the incident angle of light and the reflectance when the refractive index of the protective sheet layer is 1.7. FIG. 11 is an explanatory diagram when light passes through the glass substrate and the protective sheet layer. FIG. 12 is an explanatory diagram showing changes in the angle of light when the refractive index of the protective sheet layer is 1.4. FIG. 13 is an explanatory diagram showing changes in the angle of light when the refractive index of the protective sheet layer is 1.7. FIG. 14 is an explanatory diagram showing ease of light reception by the light receiving element of light reflected by the protective sheet interface. FIG. 15 is an explanatory diagram showing the number of light rays applied to the light receiving element with respect to the incident angle of the light to the protective sheet layer shown in FIG. FIG. 16 is an explanatory diagram illustrating a modification of the contact image reading apparatus according to the embodiment. FIG. 17 is an explanatory diagram illustrating a modification of the contact image reading apparatus according to the embodiment. FIG. 18 is a schematic diagram illustrating a modification of the contact image reading apparatus according to the embodiment. FIG. 19 is a diagram illustrating a state in which the lid of the contact image reading apparatus illustrated in FIG. 18 is opened.

  Hereinafter, embodiments of a contact image reading sensor and a contact image reading device according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

Embodiment
FIG. 1 is a diagram illustrating an appearance of a contact image reading apparatus according to an embodiment, and is a diagram illustrating a state in which a lid is closed. FIG. 2 is a diagram illustrating a state in which the lid of the contact image reading apparatus illustrated in FIG. 1 is opened. The close contact image reading apparatus 1 shown in the figure has a lid portion 5 and a main body portion 6 both formed in a thin, substantially rectangular parallelepiped or substantially plate shape. Both sides are connected by a hinge 8. Thereby, the cover part 5 and the main-body part 6 are provided so that opening and closing is possible relatively. Of these, the main body 6 is provided with an image reading sensor 10 which is a contact-type image reading sensor that reads an image in a state where the document is in close contact with the surface on the lid 5 side when the lid 5 is closed. ing.

  The lid 5 and the main body 6 are provided with an open / close detection mechanism (not shown) that can detect the open / close of both by a mechanical sensor, a magnetic sensor, an optical sensor, or the like. Further, the lid 5 or the main body 6 is provided with a reading start instruction means (not shown) such as a start button for giving an instruction to start reading when reading the image of the document 40.

  FIG. 3 is a cross-sectional view showing the configuration of the image reading sensor shown in FIG. The image reading sensor 10 provided in the main body 6 includes a surface light source 20 that is a light source that emits surface light, and a light receiving layer 15 that is provided on the surface light source 20 and receives light reflected from a document when reading an image. A protective sheet layer 25 provided by a transparent member that transmits light is laminated on the light receiving layer 15. In the image reading sensor 10 laminated in this manner, the protective sheet layer 25 is located on the lid 5 side when the lid 5 is closed and faces the lid 5, and the surface light source 20 is connected to the main body 6. It is provided in a direction located on the inner side.

  In addition, the light receiving layer 15 of the image reading sensor 10 includes a transparent glass substrate 17 provided on the surface light source 20 and a plurality of light receiving elements arranged in a two-dimensional array at predetermined intervals on the glass substrate 17. 16. The light receiving element 16 is disposed on the surface of the glass substrate 17 opposite to the side where the surface light source 20 is located, that is, the surface of the glass substrate 17 on the side where the protective sheet layer 25 is located. The image reading sensor 10 is provided as a two-dimensional contact type sensor that is a two-dimensional contact type image reading sensor 10 in which a plurality of light receiving elements 16 are arranged in a two-dimensional array as described above.

  The surface light source 20 is a surface emitting semiconductor laser array. The surface light source 20 composed of this surface-emitting type semiconductor laser array is provided as a light source that emits only substantially parallel light when emitting light. The surface light source 20 emits parallel light orthogonal to the light emitting surface of the surface light source 20 by increasing the light component in the thickness direction of the light receiving layer 15 of the protective sheet layer 25 as compared with the diffused light when emitting light. In other words, light is emitted in the thickness direction of the protective sheet layer 25 and the light receiving layer 15 to be laminated.

  Further, the surface light source 20 is provided on the opposite side of the glass substrate 17 from the side where the light receiving element 16 is located. Since the surface light source 20 emits surface light during light emission, parallel light during light emission is emitted from the glass substrate. It is possible to irradiate the entire surface on the surface light source 20 side in FIG. The glass substrate 17 is provided by a transparent member mainly made of a glass material. For these reasons, when the surface light source 20 emits light, the light from the surface light source 20 is transmitted through the glass substrate 17, and between the plurality of light receiving elements 16, the side opposite to the side where the surface light source 20 is located on the glass substrate 17. Irradiated in the direction.

  That is, the plurality of light receiving elements 16 on the transparent glass substrate 17 are arranged such that the adjacent light receiving elements 16 are separated from each other, and a portion between the adjacent light receiving elements 16 is formed with the opening 18. It has become. In this way, it is a portion between the light receiving element 16 and the light receiving element 16, and since there is no one that shields light, when the surface light source 20 emits light, this light passes through the opening 18, The glass substrate 17 can emit light in the direction opposite to the side where the surface light source 20 is located. That is, light from the surface light source 20 when the surface light source 20 emits light is emitted from the side of the light receiving layer 15 where the protective sheet layer 25 is located through the opening 18, and is irradiated in the direction of the protective sheet layer 25. As described above, the surface light source 20 is provided as an illumination unit that irradiates light emitted from the surface light source 20 in the direction from the opening 18 of the light receiving layer 15 to the protective sheet layer 25.

  The light from the surface light source 20 at the time of light emission of the surface light source 20 is thus emitted from the opening 18 in the direction of the protective sheet layer 25. The light receiving elements 16 disposed on the glass substrate 17 are respectively Since the openings 18 are spaced apart from each other, the opening 18 is located around each light receiving element 16. For this reason, the light irradiated from the opening 18 toward the protective sheet layer 25 is irradiated from the periphery of each light receiving element 16 toward the protective sheet layer 25.

  The image reading sensor 10 provided in this way is provided so that the light receiving element 16 provided in the light receiving layer 15 can receive the light reflected from the original so that the image of the original can be read. When the reading sensor 10 reads an image of a document, the image reading sensor 10 reads the image on the side where the light receiving element 16 is provided. That is, since the light receiving element 16 is disposed on the light receiving layer 15 on the side where the protective sheet layer 25 is disposed, the light reflected by the original is received by the light receiving element 16 through the protective sheet layer 25. Read the image on the original. For this reason, it is preferable that the protective sheet layer 25 easily transmits light. For example, the protective sheet layer 25 is preferably formed of an optical member having a high transmittance or a thin thickness. Specifically, a general display protection sheet often has a transmittance of 90% or more and a thickness of 0.5 mm or less, but the protective sheet layer 25 is more likely to transmit light. It is preferable. That is, the protective sheet layer 25 is preferably formed of an optical member having a transmittance of 90% or more or a thickness of 0.5 mm or less. Further, the protective sheet layer 25 provided to transmit light in this way is formed by a member having a refractive index between the refractive index of air and the refractive index of the glass forming the light receiving layer 15. It is preferable.

  The protective sheet layer 25 is provided to protect the light receiving layer 15. For this reason, the protective sheet layer 25 is formed of an insulating member not only to protect the light receiving layer 15 from dust but also to electrically protect the light receiving element 16.

  The image reading sensor 10 reads the image of the document by receiving the light reflected by the document by the light receiving element 16 as described above. The surface light source 20 that emits irradiation light that irradiates the document when the image of the document is read is: The image reading sensor 10 is disposed on the opposite side of the image reading side, that is, on the back side of the image reading sensor 10.

  FIG. 4 is a diagram showing an outline of the configuration of the contact image reading apparatus shown in FIG. The contact-type image reading apparatus 1 provided as described above can be controlled by a main control board 30 which is a control unit that controls each part of the contact-type image reading apparatus 1. For example, the image reading sensor 10 is connected to the main control board 30, and the image reading sensor 10 can be controlled by the main control board 30. The main control board 30 is provided with a processing unit 31, a storage unit 37, and an input / output unit 38. Among these, the processing unit 31 is provided with a CPU (Central Processing Unit) 32 that performs various arithmetic processes. ing.

  The processing unit 31 also includes an image reading unit control unit 33 that controls image reading by the image reading sensor 10, a read image capturing unit 34 that captures an image read by the image reading sensor 10, and a read image capturing unit. An image correction unit 35 that corrects the image captured in 34, and a light source control unit 36 that controls the light emission of the surface light source 20.

  The contact-type image reading apparatus 1 according to this embodiment is configured as described above, and the operation thereof will be described below. FIG. 5 is an explanatory diagram for reading an image of a document. 6 is a cross-sectional view taken along the line AA in FIG. 1 when reading an image of a document. The contact-type image reading apparatus 1 has a main body 6 positioned on the lower side in a direction in which the image reading sensor 10 is directed upward during normal use, and a lid that can be opened / closed relative to the image reading sensor 10. 5 is used as a lid for the main body 6. The case where the image of the original 40 is read by the contact image reading apparatus 1 provided in this way will be described. First, the original 40 is placed on the image reading sensor 10 provided in the main body 6 with the lid 5 opened. In this state, the lid 5 is closed with the hinge 8 as the center of rotation. As a result, the document 40 is sandwiched between the lid 5 and the main body 6, and the document 40 is in contact with the image reading sensor 10.

  Further, when the document 40 is sandwiched between the lid 5 and the main body 6, the document 40 is in a state where the surface opposite to the image reading sensor 10 is in contact with the lid 5. 5 and the image reading sensor 10 are in contact with each other. If the force in the direction of closing the lid 5 is increased in this state, the pressing force between the original 40 and the lid 5 and between the original 40 and the image reading sensor 10 increases. For this reason, the lid 5 is provided as a pressing member capable of pressing the document 40 against the image reading sensor 10 by increasing the force in the closing direction.

  As described above, when the cover unit 5 is closed with the document 40 positioned between the cover unit 5 and the main body unit 6 and the pressing force between the document 40 and the image reading sensor 10 is increased, 40 is in close contact with the image reading sensor 10. When the image of the original 40 is read, the original 40 is read in a state of being in close contact with the image reading sensor 10. Specifically, the original 40 is read in a state of being in close contact with the protective sheet layer 25 of the image reading sensor 10.

  FIG. 7 is an explanatory diagram of light emitted from the surface light source when reading an image of a document. The image of the original 40 is read by the image reading sensor 10 in such a state that the original 40 is in close contact with the image reading sensor 10. Next, an image reading operation by the image reading sensor 10 will be described. When reading the image of the document 40, the surface light source 20 of the image reading sensor 10 is caused to emit light while the document 40 is disposed on the protective sheet layer 25 side of the light receiving layer 15 of the image reading sensor 10. The surface light source 20 is provided as a light source that emits only substantially parallel light, and can emit parallel light to the entire surface of the glass substrate 17 of the light receiving layer 15 on the surface light source 20 side during light emission. It has become. For this reason, when the image is read, the light-receiving layer 15 is irradiated by the surface light source 20 by causing the surface light source 20 to emit light.

  When the light receiving layer 15 is irradiated by the surface light source 20, light from the surface light source 20 enters from the surface light source 20 side of the glass substrate 17 of the light receiving layer 15, and the glass substrate faces toward the side where the light receiving element 16 is disposed. 17 is transmitted. That is, since the surface light source 20 emits parallel light in the thickness direction of the protective sheet layer 25 and the light receiving layer 15 to be laminated at the time of light emission, the light from the surface light source 20 enters the glass substrate 17 of the light receiving layer 15. In this case, the light travels in the glass substrate 17 in the thickness direction of the light receiving layer 15 and passes through the glass substrate 17 toward the side where the protective sheet layer 25 is disposed.

  As described above, the light that reaches the portion where the light receiving element 16 is located in the light traveling from the surface light source 20 side of the glass substrate 17 to the protective sheet layer 25 side is blocked by the light receiving element 16. For this reason, this light is not emitted from the glass substrate 17. On the other hand, of the light traveling from the surface light source 20 side to the protective sheet layer 25 side of the glass substrate 17, the light reaching the opening 18, which is a portion where the light receiving element 16 is not disposed, is protected from the opening 18. The light is emitted in the direction of the sheet layer 25. Thus, the light emitted in the direction of the protective sheet layer 25 enters the protective sheet layer 25 formed by the transparent member.

  The light emitted from the opening 18 of the light receiving layer 15 enters the protective sheet layer 25 laminated on the light receiving layer 15 in this way. However, even when the light from the light receiving layer 15 enters the protective sheet layer 25, the light is protected. Parallel light in the thickness direction of the sheet layer 25 enters. That is, the surface light source 20 that irradiates this light irradiates the light passing through the inside of the protective sheet layer 25 so that the component in the thickness direction of the protective sheet layer 25 increases. Since the light entering the protective sheet layer 25 from the light receiving layer 15 in the state where the thickness direction component of the protective sheet layer 25 is increased is parallel light traveling in the thickness direction of the protective sheet layer 25, this light is From the surface side of the protective sheet layer 25 where the light receiving layer 15 is located, the opposite surface side, that is, the surface side to which the document 40 for reading an image is in close contact is directed.

  When the light traveling in the protective sheet layer 25 in this direction reaches the surface on the side where the original 40 is in close contact, the light is emitted from the surface in close contact with the original 40 and is in close contact with this surface. The original 40 is reached. That is, the light traveling in the protective sheet layer 25 is parallel light traveling in the thickness direction of the protective sheet layer 25, so that this light is in close contact with the document 40 from the inside of the protective sheet layer 25. It is in a state of proceeding in a direction substantially orthogonal to the protective sheet interface 26 that is an interface between the protective sheet layer 25 and air when the surface is viewed. Therefore, this light is not reflected so much at the protective sheet interface 26 but is transmitted through the protective sheet interface 26 and reaches the original 40 that is in close contact with the protective sheet layer 25. The light that reaches the document 40 is reflected by the document 40, and at this time, the light is reflected as reflected light according to the surface state such as the color of the surface of the document 40.

  Further, since this light is light that travels in the thickness direction of the protective sheet layer 25, the protective sheet layer 25 in the original 40 is applied to the original 40 in the same manner as when reaching the protective sheet interface 26. The document 40 is reached in a direction orthogonal to the closely contacting surface. For this reason, the light reflected by the original 40 is generally reflected in the direction in which the light is directed. That is, the reflected light reflected by the document 40 is reflected in the direction of the protective sheet layer 25, enters the protective sheet layer 25, passes through the protective sheet layer 25, and travels in the direction of the light receiving layer 15. The reflected light toward the light receiving layer 15 reaches the light receiving layer 15 from the surface of the light receiving layer 15 where the light receiving element 16 is located. Thereby, the light receiving element 16 receives the reflected light reflected by the document 40.

  The reflected light reflected by the document 40 is reflected light according to the state of the surface of the document 40, and the light receiving element 16 is provided so as to generate an electrical signal according to the received light. For this reason, the light receiving element 16 that has received the reflected light reflected by the document 40 generates an electrical signal corresponding to the state of the surface of the document 40 from which the received reflected light is reflected. Thus, the electrical signal generated by the light receiving element 16 is transmitted to the main control board 30, and the read image capturing section 34 of the main control board 30 obtains this electrical signal, whereby the image reading sensor in the document 40 is obtained. Image information of the document 40 on the side facing 10 is acquired. Thereby, the image of the original 40 is read.

  At the time of reading the image of the document 40, the light component in the thickness direction of the protective sheet layer 25 is increased as described above, thereby suppressing the light transmitted through the protective sheet layer 25 from being reflected at the protective sheet interface 26. It is possible to suppress the light reflected by the protective sheet interface 26 from being received by the light receiving element 16, but the reflectance at the protective sheet interface 26 varies depending on the incident angle of light and the refractive index of the protective sheet layer 25. . For this reason, when the reflectance at the protective sheet interface 26 is reduced for the purpose of suppressing the deterioration of the image quality at the time of reading the image of the document 40, the incident angle of the light incident on the protective sheet layer 25 is predetermined. It is preferable to irradiate with light so that it falls within the range.

  Next, the relationship between the incident angle of light, the refractive index of the protective sheet layer 25, and the reflectance of light at the protective sheet interface 26 will be described based on the results of simulation. FIG. 8 is an explanatory diagram when light passes through the protective sheet layer. When light is transmitted through the interface between members having different refractive indexes, such as the protective sheet interface 26, the reflectance at the interface varies depending on the incident angle of light, but as shown in FIG. 8 as the incident angle increases. In addition, the reflectance increases. Further, in the protective sheet layer 25 included in the contact image reading apparatus 1 according to the embodiment, when the incident angle is 45 ° or more when the refractive index of the protective sheet layer 25 is 1.4, the protective sheet is obtained from Snell's law. Total reflection is performed at the interface 26. The incident angle referred to here is a direction that enters the protective sheet layer 25 from the surface light source 20 side, that is, the thickness direction of the protective sheet layer 25 is 0 °, and is inclined from the thickness direction of the protective sheet layer 25. The incident angle is large.

  Also, this reflectivity is generally a wave whose light wave amplitude direction is perpendicular to the interface, rather than a p wave whose light wave amplitude direction is parallel to the interface. The s-wave is a higher reflectance when the light reaches the interface at the same angle.

  FIG. 9 is an explanatory diagram showing the relationship between the incident angle of light and the reflectance when the refractive index of the protective sheet layer is 1.4. For example, assuming that the refractive index of the air layer from which the light transmitted through the protective sheet layer 25 is emitted is 1.0, and the refractive index of the protective sheet layer 25 is 1.4, the protective sheet from the surface light source 20 side. When the reflectance at the protective sheet interface 26 with respect to the incident angle of the light incident on the layer 25 is calculated from the Fresnel equation, it changes as shown in FIG. That is, the p-wave reflectivity Refp, which is the reflectivity of the p-wave, suddenly increases from the vicinity where the incident angle exceeds 40 °, and the s-wave reflectivity Refs, which is the reflectivity of the s-wave, has an incident angle of 10 °. Gradually increases from around.

  Thus, since the reflectance differs between the p wave and the s wave, the average value of the reflectance of the p wave and the reflectance of the s wave is used as the reflectance of the member, and the refractive index is 1. In the case of the protective sheet layer 4 of 4, the reflectance average value RefA shown in FIG. 9 is obtained, and the reflectance gradually increases when the incident angle exceeds 20 °.

  FIG. 10 is an explanatory diagram showing the relationship between the incident angle of light and the reflectance when the refractive index of the protective sheet layer is 1.7. The reflectivity also changes depending on the refractive index of the member that transmits light, and the reflectivity tends to increase as the refractive index increases. For example, when the refractive index of the protective sheet layer 25 is 1.7, the reflectance at the protective sheet interface 26 with respect to the incident angle of light incident on the protective sheet layer 25 is p-wave reflectance as shown in FIG. Refp increases rapidly from the vicinity where the incident angle exceeds 30 °, and the s-wave reflectivity Refs gradually increases from the vicinity of the incident angle of 5 °. Further, as shown in FIG. 10, the average reflectance RefA in the protective sheet layer 25 having a refractive index of 1.7 gradually increases as the incident angle exceeds 15 °.

  As described above, the light reflectance at the protective sheet interface 26 when light enters the protective sheet layer 25 increases as the incident angle increases, and the refractive index of the protective sheet layer 25 increases. It also grows depending on.

  In addition, the light traveling from the surface light source 20 toward the protective sheet layer 25 is transmitted through the glass substrate 17 of the light receiving layer 15 and then through the protective sheet layer 25. The glass substrate 17 and the air layer around the glass substrate 17 The refractive index is different between the glass substrate 17 and the protective sheet layer 25. For this reason, when the light which goes to the protective sheet layer 25 from the surface light source 20 permeate | transmits between these, light is refracted according to the difference in refractive index. Next, the refraction of this light will be described. FIG. 11 is an explanatory diagram when light passes through the glass substrate and the protective sheet layer. As shown in FIG. 11, the light traveling from the surface light source 20 to the protective sheet layer 25 is incident on the glass substrate 17 from the air layer, incident on the protective sheet layer 25 from the glass substrate 17, and the protective sheet layer 25. This light is refracted when exiting from the air to the air layer. That is, the angle of the light passing through the glass substrate 17 and the protective sheet layer 25 changes according to the difference in refractive index.

  FIG. 12 is an explanatory diagram showing changes in the angle of light when the refractive index of the protective sheet layer is 1.4. For example, the simulation result when the refractive index of the glass substrate 17 is 1.5 and the refractive index of the protective sheet layer 25 is 1.4 will be described. In this case, the protective sheet layer 25 is more than the refractive index of the glass substrate 17. The refractive index of is smaller. When light is transmitted through an interface between members having different refractive indexes, when light is incident on a member having a high refractive index from a member having a high refractive index, the angle of the light with respect to the direction orthogonal to the interface increases. That is, the incident angle increases. On the contrary, when light is incident on a member having a high refractive index from a member having a low refractive index, the angle of the light with respect to the direction orthogonal to the interface becomes small, and the incident angle becomes small.

  For this reason, when the refractive index of the glass substrate 17 is 1.5 and the refractive index of the protective sheet layer 25 is 1.4, when the light in the direction from the surface light source 20 to the protective sheet layer 25 is irradiated, the surface light source Light incident on the glass substrate 17 from the air layer on the 20 side has a small incident angle when incident on the glass substrate 17. Further, the light incident on the protective sheet layer 25 from the glass substrate 17 has a large incident angle when incident on the protective sheet layer 25.

  Therefore, as shown in FIG. 12, the light angle in this case is the angle of light transmitted through the glass substrate 17, and the glass substrate light angle Optg is the angle of light from the surface light source 20, and the incident angle of the light source. Becomes smaller than Furthermore, the protective sheet light angle Optip, which is the angle of light transmitted through the protective sheet layer 25, is larger than the glass substrate light angle Optg.

  When the refractive index of the glass substrate 17 is 1.5 and the refractive index of the protective sheet layer 25 is 1.4, the protective sheet light angle Optip changes in this way, but the refractive index of the protective sheet layer 25 is Considering that the reflectance average value RefA in the case of 1.4 increases when the incident angle exceeds 20 °, the incident angle from the light source when the refractive index of the protective sheet layer 25 is 1.4 is It is desirable that the angle is 28 ° or less.

  FIG. 13 is an explanatory diagram showing changes in the angle of light when the refractive index of the protective sheet layer is 1.7. Next, a simulation result when the refractive index of the glass substrate 17 is 1.5 and the refractive index of the protective sheet layer 25 is 1.7 will be described. In this case, the protective sheet layer 25 is more than the refractive index of the glass substrate 17. The refractive index at is larger. For this reason, under this condition, light incident on the protective sheet layer 25 from the glass substrate 17 changes in a direction in which the incident angle becomes smaller when incident on the protective sheet layer 25. Therefore, the protective sheet light angle Optip in this case is smaller than the glass substrate light angle Optg, as shown in FIG.

  When the refractive index of the glass substrate 17 is 1.5 and the refractive index of the protective sheet layer 25 is 1.7, the protective sheet light angle Optip changes in this way, but the refractive index of the protective sheet layer 25 is Considering that the reflectance average value RefA in the case of 1.7 increases when the incident angle exceeds 15 °, the incident angle from the light source when the refractive index of the protective sheet layer 25 is 1.7 is It is desirable to make it 25 degrees or less.

  As described above, the reflectance at the protective sheet interface 26 varies depending on the incident angle of light and the refractive index of the glass substrate 17 and the protective sheet layer 25, but the light receiving element 16 of the light reflected by the protective sheet interface 26. The ease with which light is received varies depending not only on the incident angle and refractive index but also on the relative positional relationship. FIG. 14 is an explanatory diagram showing ease of light reception by the light receiving element of light reflected by the protective sheet interface. FIG. 15 is an explanatory diagram showing the number of light rays applied to the light receiving element with respect to the incident angle of the light to the protective sheet layer shown in FIG. In order to verify the ease of light reception by the light receiving element 16 based on this relative positional relationship, the refractive index of the protective sheet layer 25 is 1.4, the thickness of the protective sheet layer 25 is 70 μm, A simulation is performed in the case where the pitch is 169 μm and the aperture ratio of the light receiving layer 15 is 50%. Based on this result, the reflectance of light at the protective sheet interface 26 increases as the incident angle increases. For this reason, when the light reflected by the protective sheet interface 26 irradiates the light receiving element 16, the number of light receiving lines Rcvr, which is the number of light rays, is within a predetermined range when the incident angle to the protective sheet layer 25 is within a predetermined range. The number of lines increases as the incident angle increases.

  Here, not only the light receiving element 16 but also the opening 18 is located on the surface of the light receiving layer 15 on the protective sheet layer 25 side. Further, when the light incident on the protective sheet layer 25 is reflected at the protective sheet interface 26, the reflection angle is reflected at substantially the same angle as the incident angle on the protective sheet interface 26. For this reason, when the incident angle is increased, the reflection angle at the protective sheet interface 26 is also increased. However, when the reflection angle is larger than a predetermined angle, the light reflected by the protective sheet interface 26 is received by the light receiving element. It goes over 16 toward the opening 18 adjacent to the light receiving element 16.

  More specifically, the light incident on the protective sheet layer 25 enters the protective sheet layer 25 from the opening 18 of the light receiving layer 15 and reaches the protective sheet interface 26 near the position facing the opening 18 where the light is incident. To do. The light that has reached the protective sheet interface 26 is divided into light that is transmitted through the protective sheet interface 26 and light that is reflected by the protective sheet interface 26 according to the angle at which the protective sheet interface 26 is reached. Of the light thus divided, the light reflected by the protective sheet interface 26 is directed to the portion of the light receiving layer 15 that faces the protective sheet interface 26.

  Since the light receiving element 16 and the opening 18 are located in the portion of the light receiving layer 15 facing the protective sheet interface 26, the light reflected by the protective sheet interface 26 reaches one of these and is irradiated. However, when the incident angle is close to 0 °, most of the reflected light returns to the opening 18 when the light enters the protective sheet layer 25 from the light receiving layer 15.

  Thus, the reflected light traveling toward the light receiving layer 15 is shifted from the incident position on the protective sheet layer 25 as the incident angle on the protective sheet layer 25 increases. For this reason, the amount of the reflected light at the protective sheet interface 26 increases toward the light receiving element 16 adjacent to the opening 18 as the incident angle increases. Therefore, the number Rcvr of light receiving lines increases as the incident angle increases from the incident angle of 0 ° to a predetermined range.

  Further, since the reflected light toward the light receiving layer 15 is shifted from the incident position to the protective sheet layer 25 as the incident angle to the protective sheet layer 25 increases as described above, when the incident angle exceeds a predetermined size, The arrival position at the light receiving layer 15 goes to the other opening 18 beyond the light receiving element 16 adjacent to the opening 18 when this light is incident on the protective sheet layer 25. For this reason, when the incident angle exceeds a predetermined size, the number of light receiving lines Rcvr decreases as the incident angle increases.

  Specifically, when each part has the above-described conditions, as shown in FIG. 15, the number of light receiving lines increases as the incident angle increases in the range of the incident angle to the protective sheet layer 25 from 0 ° to about 30 °. Rcvr increases. In addition, in the range where the incident angle to the protective sheet layer 25 is about 30 ° or more, the incident angle increases, so that the number of light receiving lines Rcvr decreases.

  The number Rcvr of the light receiving lines changes according to the incident angle even when the incident angle is 45 ° or more, but the protective sheet layer 25 is totally reflected by the protective sheet interface 26 when the incident angle is 45 ° or more. do. For this reason, light having an incident angle of 45 ° or more does not function as light for reading an image of the document 40.

  In order to suppress the light receiving element 16 from receiving the reflected light at the protective sheet interface 26 when reading the image of the document 40, it is effective to suppress the reflection at the protective sheet interface 26. For this reason, when reading the image of the document 40, it is preferable to maintain a low reflectance at the protective sheet interface 26. However, the reflectance is relative to the protective sheet interface 26 when light passes through the protective sheet interface 26. Varies with angle.

  In order to suppress the reflectance at the protective sheet interface 26, it is preferable to derive an angle of light that increases the reflectance and irradiate the light so that the angle of the light with respect to the protective sheet interface 26 is within this range. . Here, the angle of light at which the reflectance increases in this way can be obtained from the Fresnel equation. When the reflectivity is calculated using the Fresnel equation, the sum of the reflectivity of the p-wave and the s-wave is almost constant up to a certain angle, and the reflectivity increases when the reflectivity is higher than that. Is defined as the angle of light at which the reflectivity increases.

  The angle of light when the light from the surface light source 20 reaches the protective sheet interface 26 also varies depending on the refractive index of the protective sheet layer 25. For this reason, when determining the angle of light at which the reflectance increases, it is appropriate to include the refractive index of the protective sheet layer 25, but the refractive index of the member used as the protective sheet layer 25 is 1 .3 to 1.7. Therefore, in consideration of the member used as the protective sheet layer 25, when the refractive index is in the range of 1.2 to 1.8, the angle of light at which the reflectance increases every time the refractive index changes by 0.1 is determined. Can be determined as shown in Table 1.

  The incident angle when the light emitted from the surface light source 20 passes through the glass substrate 17 of the light receiving layer 15 and enters the protective sheet layer 25 is the reflectance in Table 1 for each refractive index of the protective sheet layer 25. It is desirable that the angle is less than the increasing light angle. Thereby, the light transmitted through the protective sheet layer 25 is difficult to be reflected at the protective sheet interface 26, so that the light reflected by the protective sheet interface 26 can be made difficult to be received by the light receiving element 16.

  Further, the contact image reading apparatus 1 according to the present embodiment performs shading correction on the image of the original 40 read in this way. That is, the main control board 30 is also provided as a control unit that performs shading correction of the image of the document 40 read by the image reading sensor 10, and the image information of the document 40 captured by the read image capturing unit 34 is used as the main control board 30. Shading correction is performed by the image correction unit 35 of the control board 30. In other words, the image information of the document 40 captured by the read image capturing unit 34 is corrected based on the reference data for shading correction stored in the storage unit 37 of the main control board 30 in advance, and brightness unevenness is prevented. Then, the image is corrected so as to have uniform brightness.

  As reference data at the time of shading correction, white reference data, which is data serving as a reference on the white side of an image, and black reference data, which is data serving as a reference on the black side of an image, are stored in the storage unit 37. . Of the white reference data and the black reference data, the black reference data is line data with respect to the reading range of the image reading sensor 10, and the black reference data is stored in the storage unit 37 as line data. ing. In the case of performing shading correction, the contact-type image reading apparatus 1 according to this embodiment including the surface light source 20 on the back side of the image reading sensor 10 generates correction data for both the white side and the black side to generate shading correction. I do.

  Of these, the correction data on the white side compares the image data obtained when the reference sheet, which is a white reference sheet, is photographed with the white reference data stored in the storage unit 37, and the difference between the two is determined as white. Is stored in the storage unit 37 as the correction data on the side. Further, the black side correction data is a comparison between the image data obtained when the surface light source 20 is turned off and the black reference data stored in the storage unit 37, and the difference between both is compared with the black side correction data. Is stored in the storage unit 37. In the shading correction, the image information of the original 40 captured by the read image capturing unit 34 is corrected by the image correcting unit 35 using the white side correction data and the black side correction data stored in the storage unit 37. To do. As a result, luminance unevenness in the image information of the original 40 captured by the read image capturing unit 34 is suppressed, and the brightness of the entire image is corrected to a uniform brightness.

  The image reading sensor 10 described above increases the light component in the thickness direction of the protective sheet layer 25 as compared with the diffused light when irradiating the original 40 with the reflected light from the original 40. Since the surface light source 20 emits light from the opening 18 of the light receiving layer 15 in the direction of the protective sheet layer 25, the noise component can be reduced and read. That is, at the time of reading an image of the document 40, the light reflected by the document 40 and received by the light receiving element 16 is emitted from the surface light source 20 toward the document 40. This light is a surface emitting laser array. Since the light is emitted from the surface light source 20, the light component in the thickness direction of the protective sheet layer 25 is increased. For this reason, since this light travels in a direction substantially orthogonal to the protective sheet interface 26, the light is reflected from the protective sheet interface 26 when passing from the surface light source 20 through the protective sheet layer 25 toward the original 40. It has become difficult. As a result, this light is reflected by the protective sheet interface 26 before being reflected by the original 40, and the light reflected by the protective sheet interface 26 is received by the light receiving element 16, so that when the image of the original 40 is read. An increase in the noise component can be suppressed. Therefore, it is possible to suppress deterioration in image quality due to an increase in noise components when reading an image. As a result, it is possible to read an image while suppressing deterioration in image quality.

  Moreover, since the light passing through the inside of the protective sheet layer 25 is irradiated by the surface light source 20 so that the component in the thickness direction of the protective sheet layer 25 increases, the light transmitted through the protective sheet layer 25 is protected by the protective sheet. When the light is emitted from the layer 25 to the side where the original 40 is located, it is possible to more reliably suppress reflection at the protective sheet interface 26. Thereby, it can suppress more reliably that the noise component at the time of the reading of an image resulting from having received the light reflected by the protective sheet interface 26 with the light receiving element 16 increases. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  Further, since the surface light source 20 emits only substantially parallel light, it is possible to transmit the protective sheet layer 25 without diffusing light when reading the image of the document 40. For this reason, almost all of the light reaching the protective sheet interface 26 from the surface light source 20 reaches the protective sheet interface 26 at the same angle, and almost all of the light is orthogonal to the protective sheet interface 26. Reach in the direction. Thereby, it can suppress more reliably that the light which permeate | transmits the protection sheet layer 25 reflects in the protection sheet interface 26, and can suppress more reliably the increase in the noise component at the time of image reading. . As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  Further, since a surface-emitting laser array is used as the light source of the illumination unit as the surface light source 20, the light component in the thickness direction of the protective sheet layer 25 is increased as compared with the diffused light, and the protective sheet layer When providing the illumination part which irradiates light in the direction of 25, it can provide easily. Thereby, it is possible to easily suppress the light from the surface light source 20 from being reflected by the protective sheet interface 26 before being reflected by the document 40, and due to the reflection of the light at the protective sheet interface 26, It can be easily suppressed that the image quality deteriorates when the image of the document 40 is read. As a result, an image can be read more easily while suppressing deterioration in image quality.

  Moreover, since the protective sheet layer 25 is formed of an insulating member, the light receiving element 16 can be electrically protected. For example, even when the document 40 in contact with the image reading sensor 10 is charged, it is possible to prevent static electricity from being generated between the document 40 and the light receiving element 16 by forming the protective sheet layer 25 with an insulating member. The light receiving element 16 can be electrically protected. Therefore, when the light receiving element 16 that reads the image of the original 40 is protected by the protective sheet layer 25, it is not only protected from dust or from being damaged, but also electrically protected. The damage of the light receiving element 16 due to unnecessary electricity flowing through the light receiving element 16 can be suppressed. As a result, an image can be read more stably.

  Further, since the protective sheet layer 25 is formed of a member having a refractive index between the refractive index of air and the refractive index of glass, the light transmitted through the protective sheet layer 25 is protected by the protective sheet interface 26. It can suppress more reliably that it reflects with. That is, the light receiving layer 15 having the light receiving element 16 is formed by disposing the light receiving element 16 on glass, and the document 40 from which the image reading sensor 10 reads an image is the light receiving layer 15 in the protective sheet layer 25. Place on the opposite side of. Further, when the image of the original 40 is read, the light emitted from the surface light source 20 toward the protective sheet layer 25 is emitted from the opening 18 of the light receiving layer 15 toward the protective sheet layer 25. It passes through the glass and faces the protective sheet layer 25. Further, when this light reaches the document 40, it passes through the protective sheet interface 26 and reaches the document 40 in the air. Accordingly, the light emitted from the surface light source 20 passes through the glass of the light receiving layer 15, passes through the protective sheet layer 25, and then exits into the air.

  For this reason, the protective sheet layer 25 is formed of a member having a refractive index between the refractive index of air and the refractive index of glass, so that the light emitted from the surface light source 20 is applied to the thickness direction of the protective sheet layer 25. Even when a component in a direction having an angle with respect to is included, this light is refracted by the difference in refractive index when entering the protective sheet layer 25 from the glass. That is, when the light enters the protective sheet layer 25 from the glass, the traveling direction changes due to the difference in refractive index, and the angle with respect to the thickness direction of the protective sheet layer 25 decreases. Therefore, even when the light emitted from the surface light source 20 includes a component having an angle with respect to the thickness direction of the protective sheet layer 25, this angle is formed in the protective sheet layer 25 due to the difference in refractive index. Therefore, this light is difficult to be reflected at the protective sheet interface 26. Thereby, it can suppress more reliably that the noise component at the time of the image reading resulting from the reflection in the protective sheet interface 26 increases. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In addition, as described above, the protective sheet layer 25 is formed of a member having a refractive index between the refractive index of air and the refractive index of glass, so that the light emitted from the surface light source 20 is received by the light receiving layer 15. The incident angle at the time of incidence on the light can be relaxed. Thereby, reflection at the protective sheet interface 26 can be more easily suppressed, and an increase in noise components during image reading can be more easily suppressed. As a result, an image can be read more easily while suppressing deterioration in image quality.

  Further, when the protective sheet layer 25 is provided by an optical member having a high transmittance such as a transmittance of 90% or more, when the surface light source 20 irradiates the protective sheet layer 25 with this light, Diffusion in the protective sheet layer 25 can be suppressed. Thereby, the light emitted from the surface light source 20 is diffused in the protective sheet layer 25 before reaching the document 40, and the diffused light is directed to the light receiving layer 15 in the light receiving element 16 of the light receiving layer 15. It is possible to suppress an increase in noise components at the time of reading an image due to receiving light at. Accordingly, not only the light receiving element 16 is prevented from receiving unnecessary light due to reflection at the protective sheet interface 26, but also the light receiving element 16 is unnecessary due to light diffusing in the protective sheet layer 25. It is possible to suppress the reception of light, and it is possible to more reliably suppress an increase in noise components. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  Further, when the protective sheet layer 25 is provided by a thin optical member such as a thickness of 0.5 mm or less, the protective sheet layer when the protective sheet layer 25 is irradiated with light from the surface light source 20 The diffused light within 25 can be reduced. That is, when light is transmitted through the protective sheet layer 25, this light may diffuse in the protective sheet layer 25, but light passing through the protective sheet layer 25 by reducing the thickness of the protective sheet layer 25. Can be shortened. Thereby, the opportunity for light to diffuse in the protective sheet layer 25 can be reduced, and the diffused light in the protective sheet layer 25 can be reduced. Accordingly, since the light receiving element 16 of the light receiving layer 15 receives the diffused light in the protective sheet layer 25, it is possible to suppress the light receiving element 16 from receiving unnecessary light. It can suppress that a component increases. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In addition, when the protective sheet layer 25 is provided by such a thin optical member, the thickness of the image reading sensor 10 can be reduced, and the image reading sensor 10 can be downsized. . As a result, the image reading sensor 10 and the contact image reading apparatus 1 can be reduced in size.

  Further, the contact image reading apparatus 1 according to the embodiment includes the main control board 30 that performs shading correction of the image of the document 40 read by the image reading sensor 10, and therefore noise during reading of the image of the document 40. And shading correction can be appropriately performed. That is, when light is irradiated from the surface light source 20 in the direction of the protective sheet layer 25, this light is reflected at the protective sheet interface 26, and noise is generated due to the reflected light reaching the light receiving element 16. In this case, data when the surface light source 20 is turned off cannot be used as correction data on the black side during shading correction. In this case, it is necessary to prepare a black reference sheet to be used when obtaining black-side correction data. When obtaining data with such a sheet, if dust or the like adheres to the sheet, the state is corrected to the black side. Since it becomes data, the image after shading correction may be disturbed.

  On the other hand, when light is irradiated from the surface light source 20 of the image reading sensor 10 in the direction of the protective sheet layer 25, if the light is suppressed from being reflected by the protective sheet interface 26, noise at the time of image reading will be described. Therefore, the state in which the surface light source 20 is turned off can be used as black-side correction data. For this reason, when shading correction is performed, data when the surface light source 20 is turned off can be used as correction data. Therefore, black-side correction data can be obtained appropriately, and image quality after shading correction is ensured. can do. As a result, it is possible to read an image while suppressing deterioration in image quality.

  Further, by suppressing the light emitted from the surface light source 20 from being reflected at the protective sheet interface 26 and suppressing the light reflected at the protective sheet interface 26 from being received by the light receiving element 16, the black reference used for shading correction is used. There is no need to prepare a sheet. As a result, it is possible to reduce the size of the contact image reading apparatus 1 and to reduce the manufacturing cost.

  In addition, when black correction data is generated using a black reference sheet, it is necessary to consider the reflected light at the protective sheet interface 26, and therefore data of the entire image reading range of the image reading sensor 10 is required. However, when the data when the surface light source 20 is turned off is used as the correction data on the black side, the data size can be reduced. As a result, it is possible to reduce the load on the CPU 32 during shading correction. As a result, an image can be read more easily while suppressing deterioration in image quality.

  Further, since the storage unit 37 for storing the reference data at the time of shading correction is provided, the image data captured by the image reading sensor 10 is compared with the reference data and used for the shading correction when the shading correction is performed. Correction data can be easily generated. Therefore, shading correction can be performed more easily, and the image quality of the image after shading correction can be ensured more reliably. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In addition, since the black reference data at the time of shading correction is line data with respect to the reading range of the image reading sensor 10, the amount of black reference data can be reduced. Thereby, the capacity of the storage unit 37 for storing the reference data can be reduced, and since the data amount is small, the amount of data handled at the time of shading correction can be reduced, and shading correction can be performed more easily. Can do. As a result, an image can be read more easily while suppressing deterioration in image quality.

  In the contact-type image reading apparatus 1 according to the above-described embodiment, the surface light source 20 formed of a laser array is used as a light source that irradiates light in the direction of the protective sheet layer 25 when reading an image of the document 40. A light source other than the surface light source 20 may be used. As the light source, for example, a highly directional LED (Light Emitting Diode) light source in which a plurality are arranged in a planar shape may be used. By using the LED light source with such high directivity as the light source of the illumination unit, the light irradiated in the direction of the original 40 when reading the image of the original 40 can be emitted in a state where it is not diffused. Thereby, almost all of the light reaching the protective sheet interface 26 can be made to reach the protective sheet interface 26 at the same angle, and almost all of the light reaches in a direction orthogonal to the protective sheet interface 26. Can be made. Therefore, it can suppress more reliably that the light which permeate | transmits the protective sheet layer 25 reflects in the protective sheet interface 26, and can suppress more the increase in the noise component at the time of image reading. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  FIG. 16 is an explanatory diagram illustrating a modification of the contact image reading apparatus according to the embodiment. The illumination unit uses a light source other than a light source that emits light in the thickness direction of the protective sheet layer 25 as a light source, and irradiates the light emitted from the light source in the direction of the protective sheet layer 25 as parallel light. It may be configured. For example, as shown in FIG. 16, a backlight 50 including, as a light source, an LED 53 that is a light emitting unit, and a light guide plate 51 and a reflection plate 52 that guide light emitted from the LED 53 to the entire glass substrate 17 of the light receiving layer 15. May be used.

  Further, in this case, a collimating lens 55 is disposed between the light receiving layer 15 and the backlight 50 as a parallel light generating unit that converts light emitted from the backlight 50 into substantially parallel light. Thereby, when reading the image of the document 40, the light emitted from the backlight 50 and made into substantially parallel light by the collimating lens 55 is irradiated in the direction of the protective sheet layer 25. That is, the light emitted from the LED 53 and guided to the entire glass substrate 17 by the light guide plate 51 and the reflection plate 52 is irradiated in the direction of the protective sheet layer 25 including the diffusion component. The collimating lens 55 positioned between the backlight 50 and the light receiving layer 15 changes the light from the backlight 50 irradiated with the diffusion component into substantially parallel light, and the light in the thickness direction of the protective sheet layer 25. The component is increased and irradiated in the direction of the protective sheet layer 25.

  As a result, light that has entered the glass substrate 17 as substantially parallel light by the collimator lens 55 is incident on the protective sheet layer 25 from the glass substrate 17 of the light receiving layer 15 in the state of substantially parallel light, and the thickness of the protective sheet layer 25. The protective sheet layer 25 is transmitted in the vertical direction. For this reason, most of the light incident on the protective sheet layer 25 is not reflected by the protective sheet interface 26 but is transmitted through the protective sheet interface 26, reflected by the document 40, and reflected light by the light receiving element 16 of the light receiving layer 15. An image is read by receiving light.

  As described above, the illumination unit is configured using the backlight 50 that is a light source and the collimator lens 55 that makes the light emitted from the backlight 50 substantially parallel light, so that the image of the document 40 can be more reliably displayed. The light used for reading can be irradiated in the direction of the protective sheet layer 25 by increasing the light component in the thickness direction of the protective sheet layer 25 compared to the diffused light. Moreover, when providing the illumination part which irradiates such light, it can provide easily by using the collimating lens 55. FIG. Therefore, the light quality from the backlight 50 and the collimating lens 55, which are the illumination parts, is reflected by the protective sheet interface 26, so that the image quality is deteriorated more reliably when the image of the document 40 is read. Can be easily suppressed. As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  In addition, by using the collimator lens 55 as the parallel light generation unit, when the light emitted from the backlight 50 is irradiated in the direction of the protective sheet layer 25, the light is irradiated more reliably and easily as substantially parallel light. be able to. Thereby, it can suppress more reliably and easily that the light which permeate | transmits the inside of the protective sheet layer 25 reflects in the protective sheet interface 26. FIG. As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  Note that the parallel light generator that changes the light emitted from the backlight 50 into substantially parallel light may use an optical member other than the collimating lens 55. For example, a prism sheet (not shown) may be used as the parallel light generator. By using a prism sheet as the parallel light generation unit, when the light emitted from the backlight 50 is irradiated in the direction of the protective sheet layer 25, the prism sheet is more reliably and easily converted into substantially parallel light. can do. Thereby, it is possible to more reliably and easily suppress the deterioration of the image quality at the time of reading the image of the document 40 due to the light from the illumination unit being reflected by the protective sheet interface 26. . As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  In addition, by using the collimating lens 55 and the prism sheet as described above, it is possible to reduce the size, thickness, and weight of the illumination unit that generates parallel light. As a result, the image reading sensor 10 and the contact image reading apparatus 1 can be reduced in size and weight.

  FIG. 17 is an explanatory diagram illustrating a modification of the contact image reading apparatus according to the embodiment. Moreover, you may use things other than optical members, such as a collimating lens 55 and a prism sheet, for a parallel light production | generation part. For example, as shown in FIG. 17, a slit plate 60 may be used for the parallel light generation unit. Specifically, the slit plate 60 is provided in a shape in which a plurality of slits in the thickness direction of the protective sheet layer 25 are formed between the light receiving layer 15 and the backlight 50 in the same manner as the collimating lens 55 described above. .

  As a result, only the component that can emit light from the backlight 50 and travel toward the light receiving layer 15 including the diffusing component passes through the slit of the slit plate 60 passes through the slit plate 60. The direction component is shielded by the slit plate 60. That is, the light emitted from the backlight 50 is incident on the glass substrate 17 of the light receiving layer 15 by the slit plate 60 as only substantially parallel light in the thickness direction of the protective sheet layer 25 and enters the protective sheet layer 25. Incident. Thereby, the incident light to the protective sheet layer 25 is at an angle close to the thickness direction of the protective sheet layer 25 and the incident angle is close to 0 °, so that it is difficult to reflect at the protective sheet interface 26.

  As described above, by using the slit plate 60 as the parallel light generation unit, when the light emitted from the backlight 50 is irradiated in the direction of the protective sheet layer 25, the light is more reliably and easily made substantially parallel light. Can be irradiated. Thereby, it can suppress more reliably and easily that the light which permeate | transmits the inside of the protective sheet layer 25 reflects in the protective sheet interface 26. FIG. As a result, an image can be read more reliably and easily while suppressing deterioration in image quality.

  The illumination unit may be provided with a polarizing filter (not shown). In this case, the polarizing filter is disposed between the backlight 50 and the light receiving layer 15 in the same manner as the collimating lens 55 described above. In addition, this polarizing filter uses a polarizing filter that can irradiate light emitted from the backlight 50 in the direction of the protective sheet layer 25 with only a p-wave component. The illumination unit is configured by using the polarizing filter and the backlight 50 as described above, and the light emitted from the backlight 50 is irradiated in the direction of the protective sheet layer 25 by using the polarizing filter as a component of only the p wave. By this, it can suppress more reliably that the light which permeate | transmits the inside of the protective sheet layer 25 reflects in the protective sheet interface 26. FIG.

  In other words, when light is transmitted through the interface between objects having different refractive indexes, the reflectance of light at this interface is a p-wave whose light wave amplitude direction is parallel to the interface, and light. The s wave has a higher reflectivity when the light reaches the interface at the same angle than the p wave. (See FIGS. 9 and 10). For this reason, a polarizing filter is provided between the backlight 50 and the light receiving layer 15, the light emitted from the backlight 50 is polarized by the polarizing filter, and only the p-wave component is irradiated in the direction of the protective sheet layer 25. Thus, when the light transmitted through the protective sheet layer 25 reaches the protective sheet interface 26, it can be made difficult to reflect at the protective sheet interface 26. Accordingly, it is more certain that the noise component at the time of image reading increases due to the light irradiated in the direction of the protective sheet layer 25 receiving the light reflected by the protective sheet interface 26 by the light receiving element 16. Can be suppressed. As a result, it is possible to read an image more reliably while suppressing deterioration in image quality.

  In the contact image reading apparatus 1 according to the embodiment, the black reference data used for shading correction is line data with respect to the reading range of the image reading sensor 10, but the black reference data is the image reading sensor. 10 may be common data in the reading range. By making the black reference data at the time of shading correction one data common to the reading range of the image reading sensor 10, the data amount of the black reference data can be further reduced. That is, shading correction is performed using the same black reference data common to all pixels by suppressing light from the surface light source 20 from being reflected by the protective sheet interface 26 and suppressing sensitivity unevenness at each light receiving element 16. be able to. As a result, the amount of data to be processed at the time of shading correction is reduced, so that shading correction can be performed more easily. As a result, an image can be read more easily while suppressing deterioration in image quality.

  In the contact image reading apparatus 1 according to the embodiment, only one image reading sensor 10 is provided in the main body 6, but a plurality of image reading sensors 10 may be provided. FIG. 18 is a schematic diagram illustrating a modification of the contact image reading apparatus according to the embodiment. FIG. 19 is a diagram illustrating a state in which the lid of the contact image reading apparatus illustrated in FIG. 18 is opened. For example, the image reading sensor 10 is not only provided in the main body 6, but also provided with a second image reading sensor 72 that can read the image of the document 40 on the lid 5 that is a pressing member, as shown in FIG. 19. May be. That is, in this case, the main body 6 is provided with the first image reading sensor 71 as the image reading sensor 10 as in the contact image reading apparatus 1 according to the embodiment, and the lid 5 is closed with the lid 5 closed. The second image reading sensor 72 is provided on the surface of the main body 6 at the time of contact. The first image reading sensor 71 and the second image reading sensor 72 are arranged at positions where they overlap when the lid 5 and the main body 6 are closed.

  When the image of the original 40 is read by the contact image reading apparatus 1 provided as described above, the original 40 is covered by closing the cover 5 with the original 40 placed on the first image reading sensor 71. It is sandwiched between the part 5 and the main body part 6. As a result, the document 40 is sandwiched between the first image reading sensor 71 and the second image reading sensor 72, that is, the first image reading sensor 71 and the second image reading sensor 72 are placed on both sides of the document 40. Will be in a position. Thereby, when reading the image of the document 40, the images on both sides of the document 40 are read by the first image reading sensor 71 and the second image reading sensor 72. Therefore, when reading the images on both sides of the document 40, the first image reading sensor 71 and the second image reading sensor 72 can read the images simultaneously. Therefore, when reading both sides, it is easy and short. Can be read.

  In addition, the contact image reading apparatus 1 that sandwiches the document 40 in this way may be provided with a portion for displaying an image read by the image reading sensor 10. For example, as shown in FIG. 18, an image display unit 75 that displays an image to be read by the image reading sensor 10 may be provided on the surface of the lid 5 opposite to the side facing the main body 6. As a result, when the image reading sensor 10 reads the image of the original 40 and stores it in the storage unit 37, it can be stored after a desired reading state is obtained. Thereby, a desired image can be obtained more reliably.

  As described above, the contact-type image reading sensor and the contact-type image reading apparatus according to the present invention are useful for an image reading apparatus that reads an image by bringing the document into close contact with the contact-type image reading sensor that reads an image. This is suitable for a contact image reading apparatus that emits light used for reading an image of an original from the side opposite to the original reading surface of the reading sensor.

DESCRIPTION OF SYMBOLS 1 Contact type image reading apparatus 5 Cover part 6 Main body part 10 Image reading sensor 15 Light receiving layer 16 Light receiving element 17 Glass substrate 18 Opening part 20 Surface light source 25 Protective sheet layer 26 Protective sheet interface 30 Main control board 31 Processing part 32 CPU
40 Document 50 Backlight 51 Light guide plate 52 Reflector 53 LED
55 Collimating lens 60 Slit plate

Claims (18)

A light-receiving layer having a plurality of light-receiving elements arranged two-dimensionally;
A protective sheet layer that is disposed on a light receiving side surface of the light receiving element in the light receiving layer and transmits light;
A light source that emits light, and the light component in the thickness direction of the protective sheet layer is increased as compared with the diffused light, and the light emitted by the light source is transmitted between the light receiving elements in the light receiving layer. An illuminating unit for irradiating light in the direction of the protective sheet layer;
A contact-type image reading sensor comprising:   The contact-type image reading device according to claim 1, wherein the illumination unit irradiates light so that light passing through the inside of the protective sheet layer increases a component in a thickness direction of the protective sheet layer. Sensor.   The contact-type image reading sensor according to claim 1, wherein the light source emits only substantially parallel light.   The contact-type image reading sensor according to claim 3, wherein the light source is an LED light source having a high directivity arranged in a planar shape.   The contact-type image reading sensor according to claim 3, wherein a surface emitting laser array is used as the light source.   The illumination unit includes a parallel light generation unit that converts light emitted from the light source into substantially parallel light, and the protective sheet layer converts light emitted from the light source into substantially parallel light from the parallel light generation unit. The contact-type image reading sensor according to claim 1, wherein the contact-type image reading sensor is irradiated in the direction of.   The contact-type image reading sensor according to claim 6, wherein a prism sheet is used for the parallel light generation unit.   The contact-type image reading sensor according to claim 6, wherein a collimating lens is used for the parallel light generation unit.   The contact-type image reading sensor according to claim 6, wherein a slit plate is used for the parallel light generation unit.   The illumination unit includes a polarization filter, and irradiates light emitted from the light source in a direction of the protective sheet layer by using the polarization filter as a component of only a p-wave. Or a contact image reading sensor according to 2;   The contact type image reading sensor according to claim 1, wherein the protective sheet layer is an optical member and has a high transmittance.   The contact-type image reading sensor according to claim 1, wherein the protective sheet layer is formed of an optical member having a small thickness.   The contact image reading sensor according to claim 1, wherein the protective sheet layer is formed of an insulating member.   The contact type image reading apparatus according to claim 1, wherein the protective sheet layer is formed of a member having a refractive index between a refractive index of air and a refractive index of glass. Sensor. A contact image reading sensor according to any one of claims 1 to 14,
A control unit that performs shading correction of an image of a document read by the contact image reading sensor;
A contact-type image reading apparatus comprising:   The contact image reading apparatus according to claim 15, further comprising a storage unit that stores reference data for performing the shading correction.   Among the reference data, black reference data serving as a reference on the black side of an image read by the contact image reading sensor is line data with respect to a reading range by the contact image reading sensor. The contact image reading apparatus according to claim 16.   Among the reference data, black reference data serving as a reference on the black side of an image read by the contact-type image reading sensor is one data common to the reading range of the contact-type image reading sensor. The contact image reading apparatus according to claim 16.

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