JP5418634B2 - Contact image sensor and illumination optical system - Google Patents

Description

  The present invention relates to a contact-type image sensor and an illumination optical system on which a condenser lens and a light guide are mounted.

  In order to read image information at high speed, it is desired to irradiate a reading surface with a larger amount of light, and for this purpose, a function having a light condensing function may be used. For example, FIG. 2 (see Patent Document 1) of Japanese Patent Laid-Open No. 5-181004 discloses an image sensor in which an assembly body composed of an LED printed board 4 and a condenser lens 21 is attached to an attachment surface 6 of a base 7. Has been.

  Also, in the case where uniform light irradiation in the longitudinal direction is performed as the light source of the contact image sensor, a light source is arranged at the end in the longitudinal direction and light is emitted from the same light source in the longitudinal direction rather than a configuration having a plurality of light sources in the longitudinal direction. If the light is propagated and diffused, it is easier to obtain a uniform amount of irradiation light, and the structure is inexpensive. For example, in FIG. 1 (see Patent Document 2) of Japanese Patent Laid-Open No. 2000-125080, the light source 3 is mounted at the end of the light guide 8 for guiding the light emitted from the light source 3 to the line-shaped image reading region. An image reading apparatus is disclosed.

Japanese Patent Laid-Open No. 5-181004 (FIG. 2) Japanese Unexamined Patent Publication No. 2000-125080 (FIG. 1)

  However, in the image sensor described in Patent Document 1, the light emitted from the LED 3 is collected by reflection or refraction in the condenser lens 21 and is irradiated to the read portion of the document 14 as parallel rays. Therefore, although the portion to be read of the document 14 is brightly illuminated at necessary portions, since many point light sources are arranged in the longitudinal direction, it is difficult to perform uniform illumination in the longitudinal direction. There was a problem of becoming an expensive image sensor.

  Further, in the image reading device described in Patent Document 2, although the amount of light irradiated to each part in the longitudinal direction of the image reading region can be made uniform, the shape of the light guide 8 is large and complicated, so that the light source 3 The structure of the case 1 that accommodates the substrate 4 and the light guide 8 placed thereon is complicated, and there is a problem that the illuminance for illuminating the document surface varies due to tolerances at the time of incorporation.

  The present invention has been made to solve the above-described problems, and ensures a uniform irradiation performance in the longitudinal direction, efficiently irradiates a document surface, and has a good built-in image sensor and illumination optics. The purpose is to provide a system.

Contact image sensor according to the invention of claim 1 includes a light guide extending in the reading width direction of the originals, provided along the light guide, condensing the light emitted from the light guide And then, a condensing unit that irradiates the irradiating unit of the original, a condensing lens including a flange extending from the condensing unit, a light source that makes light incident on the light guide, and a reading width of the original A lens that extends in the direction and is arranged on the opposite side of the condensing unit with respect to the condensing unit, and converges the reflected light reflected from the irradiating unit of the document on the light receiving unit. an array, to accommodate the light guide, and a housing in which is placed the flange portion formed stepped portion on the opposite side of the lens array with respect to the portion for accommodating the light guide, wherein the flange The portion has a support portion that protrudes toward the light guide body and contacts the light guide body. It is intended.

According to a second aspect of the present invention, there is provided the contact image sensor according to the first aspect, wherein a plurality of the support portions are arranged along a reading width direction of the original .

A contact image sensor according to a third aspect of the present invention includes a light guide that extends in the reading width direction of the document, and a light guide that is provided along the light guide to collect light emitted from the light guide. A condensing unit that irradiates the irradiating unit of the original document, and a condensing lens composed of a flange extending from the condensing unit, and a flat plate that is installed at the end of the condensing lens and the light guide. A holder for holding the light guide by inserting an end of the light guide to one end of the hole and fixing the end of the condenser lens outside the hole; A light source that makes light incident on the light guide, and extends in the reading width direction of the document, is disposed on the opposite side of the condensing unit with respect to the condensing unit, and the light irradiated from the condensing lens The lens array for converging the reflected light reflected by the irradiating portion of the document and the light guide are housed, and the light guide A projection portion and a recess portion in which the condensing lens and the holder are cut and formed, and a step portion formed on the opposite side of the lens array with respect to the portion housing the lens array. The light guide and the holder are fitted by a protrusion at the end of the light guide and a recess provided in the hole of the holder .

An illumination optical system according to a fourth aspect of the invention includes a light guide that extends in the reading width direction of the document, and a light guide that is provided along the light guide to collect light emitted from the light guide. From the condensing unit that irradiates the irradiating unit of the original document, a condensing lens that includes a flange extending from the condensing unit, a light source that makes light incident on the light guide, and the condensing lens A hole through which the reflected light reflected by the irradiating part of the document passes, houses the light guide, and is formed on the side opposite to the hole with respect to the part containing the light guide. comprising a a housing which is placed the flange portion to the stepped portion, the flange portion may protrude toward the light side, it's also that have a support portion in contact with the light guide.

The illumination optical system according to a fifth aspect of the present invention is the illumination optical system according to the fourth aspect, wherein a plurality of the support portions are arranged along the reading width direction of the original.

An illumination optical system according to a sixth aspect of the invention includes a light guide that extends in the reading width direction of the document, and a light guide that is provided along the light guide and condenses light emitted from the light guide. A condensing unit that irradiates the irradiating unit of the original document, and a condensing lens composed of a flange extending from the condensing unit, and a hole formed in the end of the condensing lens and the light guide. A holder for holding the light guide by inserting an end of the light guide into one end of the hole and fixing the end of the condenser lens outside the hole; a light source for incident light into the light guide member, the condenser lens the light emitted from the have a hole for passing reflected light reflected by the irradiated portion of the document, to accommodate the light guide, wherein the guide provided that it has placed the flange portion formed stepped portion on the opposite side of the hole with respect to housing portion of the optical body housing front Fitted between the recess condenser lens and the projection portion formed cutout the holder, the light guide member and the holder is provided in the hole portion of the the protrusion of the end portion of the light guide holder It is what is fitted by the hollow part .

As described above, according to the inventions according to claims 1 to 3 , a contact image capable of ensuring uniform irradiation performance in the longitudinal direction with the light guide and efficiently irradiating the document surface with the condenser lens. There is an effect of obtaining a sensor.

According to the inventions according to claims 4 to 6 , there is an effect of obtaining an illumination optical system capable of ensuring uniform irradiation performance in the longitudinal direction by the light guide and efficiently irradiating the document surface by the condensing lens. .

1 is an exploded perspective view of the overall configuration of a contact image sensor according to Embodiment 1 of the present invention. 1 is a cross-sectional view of a contact image sensor according to Embodiment 1 of the present invention. It is an expanded block diagram explaining fitting of the light guide of the contact | adherence image sensor by Embodiment 1 of this invention, and a condensing lens. It is a partial expansion expansion block diagram explaining fitting with the light guide and holder of the contact | adherence image sensor by Embodiment 1 of this invention. It is a partial expansion expansion block diagram explaining fitting with the condensing lens and holder of the contact | adherence image sensor by Embodiment 1 of this invention. It is a partial expansion expanded configuration figure explaining attachment of a contact type image sensor by Embodiment 1 of this invention. It is an external view explaining positioning fixation of the board | substrate and elastic member of the contact | adherence type image sensor by Embodiment 1 of this invention. It is sectional drawing of the contact type image sensor by Embodiment 2 of this invention. It is an external view of the condensing lens used for the contact | adherence image sensor by Embodiment 2 of this invention.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIG. FIG. 1 is an exploded perspective view of the overall configuration of a contact image sensor (image sensor) according to the first embodiment. In FIG. 1, 1 is a document (object to be irradiated) conveyed in the conveyance direction (sub-scanning direction) of the contact image sensor, 2 is a housing for housing components mounted on the contact image sensor, and 3 is a main scanning direction. A transparent light guide 4 that extends in the (reading width direction) and transmits light, and 4 concentrates the light emitted from the light guide 3 at the reading position (irradiation unit) in the main scanning direction of the document 1 located above. The transparent condensing lens 5 for illumination is provided at the end of the light guide 3 or the condensing lens 4, has a hollow region, and enters the light guide 3 from the end incident surface of the light guide 3. It is a holder in which a light propagation path is formed. The holders 5 are installed at both ends in the reading width direction.

  Reference numeral 6 denotes a transparent transmissive member that is interposed between the condenser lens 4 and the document 1 and forms a conveyance path and prevents foreign matters from entering, and 7 is a rod lens array (lens) that focuses light reflected from the document surface. Body). A sensor IC 8 photoelectrically converts light converged by the rod lens array 7 by linearly arranging a large number of light receiving portions, and a sensor substrate 9 on which the sensor IC 8 and the like are mounted. The sensor substrate 9 outputs the photoelectric conversion signal photoelectrically converted by the sensor IC 8 as an image signal from a connector (not shown) or the like to the outside. The sensor substrate 9 on which the rod lens array 7 and the sensor IC 8 are mounted is called an imaging optical system. In the drawings, the same reference numerals indicate the same or corresponding parts.

  Reference numeral 10 denotes a light source constituted by an LED or a bare chip in which an LED chip is resin-molded, and 11 is a bendable substrate (flexible substrate) on which the light source is placed, and has lead terminals extended from the wall surface of the holder 5. Reference numeral 12 denotes an elastic member such as a leaf spring made of sheet metal, 13 denotes a bracket that covers both ends of the contact image sensor in the reading width direction, 14 denotes a mounting screw (attachment means) for fixing a component, and 15 denotes a contact image sensor. The housing 2 is threaded.

  FIG. 2 is a cross-sectional view of the contact image sensor according to the first embodiment. In FIG. 2, the light guide 3 has a core shape or a substantially circular cross section, and a light scattering layer (light scattering region) that scatters or reflects light along the reading width direction is formed. A light-scattering layer is comprised by the white silk printing pattern or vapor deposition pattern on the light-guide 3 surface. As another method, a method of providing a kerf in the light guide 3 or a configuration in which the surface roughness of the light guide 3 is increased may be employed. The pattern of the light scattering layer is arranged by appropriately adjusting the pattern shape and pattern pitch to obtain uniform light emission over the reading width direction. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

  Light that passes through the internal light guide path of the light guide 3 from the exit portion (light exit portion) of the portion facing the light scattering layer with respect to the central axis of the light propagation direction of the light guide 3 radiates toward the condenser lens 4 side. Is done. The condensing lens 4 is separated from the light guide 3 and illuminates the irradiating portion with the irradiation light from the light guide 3 through the transmission body 6.

  FIG. 3 is a developed configuration diagram illustrating the fitting of the light guide body and the condensing lens of the contact image sensor according to Embodiment 1 of the present invention. In FIG. 3, 3a is a protrusion provided at the end of the light guide 3, 4a is a protrusion provided at the end of the condenser lens 4 side, and 4b is a recess provided at the end of the condenser lens 4 side. , 5a is a hole in the holder 5, 5b is a recess provided in the hole of the holder 5, 5c is a protrusion provided in the holder 5, 5d is a recess provided in the holder 5, and 5e is a holder 5 These are dowels (protrusions) for alignment provided on the outer sides of both ends. Note that the protrusion 5 c and the recess 5 d provided on the holder 5 are also referred to as notch portions of the holder 5. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

  FIG. 4 is a partially enlarged configuration diagram for explaining the fitting between the light guide and the holder of the contact image sensor according to Embodiment 1 of the present invention. In FIG. 4, the light guide 3 inserts the end protrusion 3 a of the light guide 3 into the hole 5 a of the holder 5, and the protrusion 3 a of the light guide 3 is a recess provided in the hole 5 a of the holder 5. 5b is fitted (fitted). The recessed portion 5b does not necessarily have to penetrate in the main scanning direction side, and by positioning the projection 3a of the light guide 3, the positioning or mounting accuracy of the light guide 3 based on the abutting position can be improved. . 3, the same reference numerals as those in FIG. 3 denote the same or corresponding parts.

  As described above, even in the case of the light guide 3 having the shape of the core cylindrical light guide path, the irradiation angle of the emission part of the light guide 3 is fixed by the projection 3a and the holder 5, and the rotation deviation of the light guide 3 is fixed. This prevents an irradiation deviation on the side of the sub-scanning direction with respect to the irradiation part.

  FIG. 5 is a partially enlarged configuration diagram for explaining the fitting of the condenser lens and the holder of the contact image sensor according to Embodiment 1 of the present invention. In FIG. 5, the condensing lens 4 inserts the end protrusion 4 a and the depression 4 b of the condensing lens 4 into the protrusion 5 c and the depression 5 d of the holder 5, and the protrusion 4 a and the depression of the condensing lens 4. 4b is fitted (fitted) with the recess 5d and the protrusion 5c of the holder 5. The protrusions 5c and the recesses 5d do not necessarily have to penetrate in the main scanning direction, and the condensing lens 4 can be positioned with reference to the abutting position by abutting the protrusions 4a and the recesses 4b of the condenser lens 4. Mounting accuracy can be improved. In the figure, the same reference numerals as those in FIG. 3 denote the same or corresponding parts.

  From the above, the light source 10, the light guide 3, and the condenser lens 4 are held in a fixed arrangement with the holder 5 as a reference by connecting the holder 5 to a component that is fixed or fitted with the reference. It is possible to perform uniform irradiation with no variation. Moreover, the light guide 3, the condensing lens 4, and the holder 5 are made into a kit in advance and are incorporated into the housing 2, so that the assemblability including the positional accuracy is improved.

  FIG. 6 is a partially enlarged configuration diagram for explaining the attachment of the contact image sensor according to the first embodiment of the present invention. In FIG. 6, 2a is an end opening (opening) of the housing 2, 5f is a bottom surface of the holder 5, and 11a is a sheet metal (metal plate) that protects the light source 10 portion of the flexible substrate 11 from bending and bending. 11b indicate lead terminals for supplying power to the light source 10 from the outside. 12 a is a pressing portion of the elastic member 12, 12 b is a bent sheet metal portion covering the notch portion of the holder 5 of the elastic member 12, and 12 c is an elastic portion of the elastic member 12. In the first embodiment, the elastic portion 12c uses a leaf spring, but a flat rubber material or a resilient silicon adhesive may be used. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

  A light source 10 such as an LED is mounted on a flexible substrate 11, and the lead terminal 11b plays a role of electrical connection with the outside. The flexible substrate 11 is connected to an elastic member 12 having an elastic portion 12c such as a stretchable leaf spring, and finally the bracket 13 is overlapped and screwed to the housing 2 with a screw 14 (attachment means). The screwing may be performed by temporarily fixing the elastic member 12 and the housing 2 and then screwing the bracket 13 and the housing 2 with the elastic member 12 sandwiched therebetween. As shown in FIG. 7, the flexible substrate 11 and the elastic member 12 are temporarily fixed and fixed by a dowel 5 e provided in the holder 5 in the order of the flexible substrate 11, the sheet metal 11 a, and the elastic member 12 in order of the holder 5. To do.

  That is, in the tightening process for storing the condenser lens 4 and the light guide 3 assembled with the holder 5 as a reference in the housing 2, the condenser lens 4, the light guide 3 and the holder 5 are stored in the housing 2. After that, the flexible substrate 11 on which the light source 10 is mounted and the elastic member 12 are inserted from both sides with reference to two dowels (holder pins) 5e protruding from the holder-5. Thereafter, the bracket 13 is attached to the attachment portion 15 using screws 14.

  From the above, the arrangement of the light source 10 and the light guide 3 is also based on the holder 5 so that the mounting accuracy of these illumination optical systems can be kept high.

  In addition, the transparent body 6 and the housing 2 may be fixed by pressing the transparent body 6 extended to the notch portion of the holder-5 by the sheet metal bending portion 12b without fixing with the adhesive. .

  With the above configuration, the condenser lens 4, the light guide 3, the holder 5, and the transmissive body 6 are fixed to each other with high positional accuracy without using an adhesive such as resin with the housing 2. This produces the effect of easy handling during assembly and repair.

  The assembled condenser lens 4, light guide 3 and holder 5 are installed inside the housing 2 with reference to the bottom surface portion 5 f of the holder 5 and the opening 2 a of the housing 2. The holder 5 is formed of a mold-molded product, and the surface accuracy of the opening 2a of the housing 2 is increased by precision machining, so that the accuracy of the holder 5 and the housing 2 is improved. The rod lens array 7 is arranged at the center of the lens 4, and the arrangement accuracy inside the condenser lens 4 in contact with the rod lens array 7 is also improved by the rod lens array 7.

  Next, the operation will be described with reference to FIGS. Both ends of the pair of condensing lenses 4 and the pair of light guides 3 are held by the holder 5 and installed inside the housing 2 in which the rod lens array 7 is arranged in the center. A light source 10 is arranged at each end of the light guide 3.

  The light emitted from the light source 10 mounted on the flexible substrate 11 passes through the hole 5a inside the holder 5 and enters from the end of the light guide 3, and main scanning while repeating total reflection inside the light guide 3. The condensing lens 4 is irradiated with illumination light that is propagated in the direction and gradually scattered and reflected by the scattering region provided in the light guide 3. The condenser lens 4 has a focal point substantially on the surface of the original, and the light is concentrated on the irradiation portion (reading position) of the original 1 being conveyed.

  The light reflected by the image information on the original surface is converged by the rod lens array 7, and the light converged by the rod lens array 7 is photoelectrically converted by the light receiving unit of the sensor IC 8 mounted on the sensor substrate 9. The photoelectrically converted output outputs information on a reading object such as the original 1 to the outside as an electrical signal.

  By the way, the photoelectric conversion output preferably has a wide dynamic range, and the drive current of the light source 10 increases when the photoelectric conversion output is driven at high speed. For example, when the light source 10 is pulse-driven, when the loss voltage of the light source is 1.5 V in addition to the amount of heat generated by the light, a driving current of about 50 mA is necessary, so that a loss power of about 75 mW is generated. Furthermore, since the light source 10 is mounted with LED light sources of a plurality of emission colors such as RGB at the same time and is driven at the same time in addition to being lit in a single color, even greater Joule heat is generated.

  In order to effectively dissipate the Joule heat, it is necessary to install the light source 10 near the metal surface and dissipate the heat conducted to the metal surface to the outside of the contact image sensor. Therefore, by using the metal plate 11a such as a sheet metal as the base of the flexible substrate 11, the heat dissipation effect is enhanced.

  The flexible substrate 11 on which the light guide 3, the condenser lens 4, and the light source 10 are mounted and the holder 5 are fixed to the housing 2 via the elastic member 12 having elasticity, so that the flexible substrate on which the light source 10 is mounted. 11 and the light guide 3 can be distorted by stretching or contracting, and stable irradiation can be performed in the reading width direction without depending on the ambient temperature environment.

Embodiment 2. FIG.
Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 8 is a cross-sectional view of the contact image sensor according to the second embodiment. In FIG. 8, reference numeral 40 a denotes a support portion (condensing lens holding rib) that is arranged in the longitudinal direction of the condensing lens 4 and is integrally formed with the condensing lens 4. 40 b is a condensing part of the condensing lens 4, and 40 c is a brim part of the condensing lens 4. In the figure, the same reference numerals as those in FIG. 2 denote the same or corresponding parts.

  The condenser lens 4 emits light scattered in an unnecessary direction in order to effectively irradiate the scattered light from the light scattering layer of the light guide 3 only in a range where the reading object such as the document 1 is disposed. It increases the light irradiation efficiency by having the role of condensing light in the required direction. In consideration of the focal depth performance range of the rod lens array 7, the position where the reading object is arranged is often limited to a range of about several mm or less in the height direction from the transmission body 6, and is limited to that range. It is effective to perform irradiation.

  The condensing lens 4 needs to maintain the positional relationship with the light guide 3 correctly in order to condense on a necessary location. Therefore, as shown in FIG. 9, the condenser lens 4 is provided with a condenser lens holding rib 40a so that the relative relationship between the light guide 3 and the condenser lens 4 is held in the longitudinal direction. The condensing lens 4 prepared as a resin molded product has a length of about 300 mm and is about 10 grams, but when held by the holder 5 located at a position 300 mm away, deflection due to its own weight of about 0.5 mm occurs.

  In order to avoid this, by installing the condensing lens holding ribs 40a at about two places with respect to the width of 300 mm, it is possible to improve the illuminance distribution in the irradiating part so as not to be affected.

  The condensing lens holding rib 40a may be separately provided as a separate part, and the light guide 3 and the condensing lens 4 may be installed near the center of the reading width direction. In the second embodiment, the condensing lens 4 is made of resin. The case where it implements without having to carry out an unnecessary individual part and an assembly process by carrying out integral molding with a molded article is explained. In addition, since it is the same as the content demonstrated in Embodiment 1 regarding fixation with the condensing lens 4 and the holder 5, the relationship between the condensing lens 4 and the light guide 3 is demonstrated.

  In FIG. 8, when the condenser lens 4 is subdivided, it is divided into a condenser part 40b and a flange part 40c, and two condenser lens holding ribs 40a integrally formed with the flange part 40c are formed as shown in FIG. The collar portion 40c is spaced from the center of the light collecting portion 40b in the irradiation direction, and the incidence of light from the light emitting portion of the light guide 3 is almost negligible. Therefore, the vicinity of the center in the reading width direction away from the light emitting portion of the light guide 3 or a plurality of condensing lens holding ribs 40a are distributed and arranged.

  As described above, by providing a structure (supporting portion) such as the condensing lens holding rib 40a for making the gap constant between the condensing lens 4 and the light guide 3 along the longitudinal direction, The gap between the condensing lens 4 is fixed not only in the holders 5 positioned at both ends, but also in the vicinity of the center portion, and there is an effect of making irradiation in the reading width direction uniform.

  Further, by providing the flange portion 40c for fixing the support portion 40a to the condenser lens 4, the cross section viewed from the reading width direction of the condenser lens 4 becomes longer. Deviations in the installation angle of the optical lens 4 can be minimized.

  In the second embodiment, two support portions 40a are arranged in the reading width region. However, one support portion 40a may be arranged in the central portion, and when the light reaches the supporting portion 40a, the entire reading width region is arranged. In addition to the effect of making the gap constant and making the irradiation in the reading width direction uniform, the illumination illuminance of the irradiation unit may be improved by providing an effect as a reflector.

  In the first and second embodiments, a flexible substrate is used as the substrate 11. However, in the case where flexibility is not required or the substrate on which the light source 10 with a relatively small number of LEDs and power loss is mounted, the substrate 11 is a glass epoxy substrate or the like. The base material used for the printed wiring board is used, and the metal plate 11a may not be used.

  In the first and second embodiments, a transparent resin or a transparent body may be provided in a light propagation region passing through the inside of the holder 5 to provide an optical filter function or a diffusion convergence function. It may not be a hole, but may have a similar configuration according to the cross-sectional shape of the light guide 3. That is, the light guide 3 has an appropriate effect even if the cross section is not only circular but elliptical, polygonal, or a connected type of these shapes.

1..Original (irradiated body) 2..Case 2a..End opening (opening)
3. ・ Light guide 3a ・ ・ Protrusion 4 ・ ・ Condenser lens 4a ・ ・ Protrusion 4b ・ ・ Recess
5 .. Holder 5 a... Hole 5 b... Recess 5 c.. Projection 5 d.. Recess 5 e.. Dowel (projection) 5 f.・ Lens body (rod lens array)
8. Sensor IC 9. Sensor board 10. Light source 11. Substrate (flexible substrate) 11a ... Sheet metal (metal plate) 11b ... Lead terminal 12 ... Elastic member 12a ... Pressing part 12b ... Sheet metal Bending part 12c ・ ・ Elastic part 13 ・ ・ Bracket 14 ・ ・ Mounting means (screw)
15 .. Mounting portion 40 a.. Support portion (condensing lens holding rib) 40 b.

Claims (6)

A light guide body that extends in the reading width direction of the originals, provided along the light guide, light collection for irradiating an irradiation portion of the document from condenses the light emitted from the light guide And a condensing lens composed of a flange extending from the condensing unit, a light source for making light incident on the light guide, and extending in the reading width direction of the original, with respect to the condensing unit A lens array that is disposed on the opposite side of the collar portion and that converges the light reflected from the illuminating portion of the original on the light receiving portion, and the light guide, is disposed on the opposite side of the flange portion, and stores the light guide. A housing in which the flange portion is mounted on a step portion formed on the side opposite to the lens array with respect to the portion containing the light body, and the flange portion protrudes toward the light guide body side, A contact-type image sensor having a support portion in contact with the light guide . The contact image sensor according to claim 1 , wherein a plurality of the support portions are arranged along a reading width direction of the document . A light guide that extends in the reading width direction of the document, and a light collecting unit that is provided along the light guide and collects the light emitted from the light guide and then irradiates the irradiation unit of the document And the condensing lens which consists of a collar part extended from this condensing part, it is installed in the end part of this condensing lens and the above-mentioned light guide, it provides a hole in a flat plate, and the above-mentioned one end side of this hole part A holder for inserting the end of the light guide to hold the light guide and fixing the end of the condenser lens outside the hole; a light source for allowing light to enter the light guide; It extends in the reading width direction of the document, and is disposed on the side opposite to the flange portion with respect to the condensing unit, and the light irradiated from the condensing lens converges the reflected light reflected by the irradiating unit of the document. A lens array and the light guide are housed, and the lens array is opposite to the portion containing the light guide. A stepped portion formed on the side, and a casing on which the collar portion is placed, and the projection lens and the recess formed by cutting out the condenser lens and the holder are fitted, and the light guide and the The holder is a close-contact image sensor that is fitted with a protrusion at an end of the light guide and a recess provided in a hole of the holder . A light guide that extends in the reading width direction of the document, and a light collecting unit that is provided along the light guide and collects the light emitted from the light guide and then irradiates the irradiation unit of the document And a condensing lens composed of a flange extending from the condensing unit, a light source for allowing light to enter the light guide, and a reflection of light emitted from the condensing lens reflected by the irradiation unit of the document A housing having a hole portion through which light passes, housing the light guide, and placing the flange portion on a step portion formed on the opposite side of the hole portion with respect to the portion containing the light guide. The illumination optical system includes a body, and the flange portion has a support portion that protrudes toward the light guide body and contacts the light guide body. The illumination optical system according to claim 4, wherein a plurality of the support portions are arranged along a reading width direction of the document. A light guide that extends in the reading width direction of the document, and a light collecting unit that is provided along the light guide and collects the light emitted from the light guide and then irradiates the irradiation unit of the document And the condensing lens which consists of a collar part extended from this condensing part, it is installed in the end part of this condensing lens and the above-mentioned light guide, it provides a hole in a flat plate, and the above-mentioned one end side of this hole part A holder for inserting the end of the light guide to hold the light guide and fixing the end of the condenser lens outside the hole ; a light source for allowing light to enter the light guide; It has a hole that reflected light reflected by the light emitted from the condenser lens is irradiated portion of the document passes, and accommodating the light guide, the hole for the portion for accommodating the light guide comprising a housing which is placed the flange portion formed stepped portion on the side opposite to the cutout of the condenser lens and the holder The light guide and the holder are engaged with each other by a protrusion at the end of the light guide and a recess provided in the hole of the holder. illumination optical system are.

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