JP4341666B2 - Contact image sensor and image reading apparatus using the same - Google Patents

Description

  The present invention relates to a contact image sensor used for image reading devices such as securities and banknote discrimination, and in particular, prevents a defocus phenomenon caused by chromatic aberration at the time of multicolor light source reading using an infrared light source, and has high accuracy. Can be read.

Japanese Patent No. 3011845 of Patent Document 1 FIG. 1 shows a focal position in which a projection is provided on a loaded document and the document is brought into contact with the apex of the projection in order to prevent a defocus phenomenon at the time of document reading. A contact image sensor that identifies the above is disclosed. In addition, an infrared light shielding paint is applied to the protrusions to allow only visible light to enter. In FIG. 1, 1 is a light source, 2 is a lens, 3 is a sensor IC, 4 is a sensor substrate, 51 is glass, 6 is a housing, 7 is a connector, 8 is a document, 9 is a transport platen, Reference numeral 10 denotes a protrusion.

  Next, the operation will be described. The light emitted from the light source 1 passes through the glass 51 and the protrusion 10 and reaches the character portion of the document 8. Light is absorbed in the black part of the character, and almost 100% of the light is reflected in the white part which is the background color of the document. The reflected light passes through the glass 51 and the protrusion 10, is collected by the lens 2, and enters the light receiving portion of the sensor IC 3 on the sensor substrate 4. The sensor IC 3 includes a plurality of light receiving units and a drive unit that photoelectrically converts light incident on each light receiving unit and extracts the output. The received light is converted into an electrical signal by the drive unit and output as image information through the connector 7. By rotating the platen 9 and transporting the document 8, continuous reading of characters and the like written on the document 8 is performed for each line.

Japanese Patent No. 30111845

  In the case of a monochromatic light source or a white light source (such as a cold-cathode tube) having a plurality of light source components, the light source itself is monochromatic light. Has been ignored. However, when reading a color document and the light source has multiple colors and is driven independently, the light reflected from the document has different conjugate lengths in the light receiving part of the sensor IC due to chromatic aberration such as a rod lens. Focus on. In particular, when an infrared (IR) light source is used, its conjugate length is extremely longer than other red (R), green (G), and blue (B) light sources. The conjugate length from the document surface to the light receiving unit of the contact image sensor is usually composed of RGB (color reading three primary colors), and when this is read with an IR light source, resolution degradation occurs. Therefore, there is a problem that all the original colors cannot be read at a high resolution.

  In addition, a light shielding technique represented by an infrared filter has been used for the purpose of cutting infrared light itself. Therefore, in principle, when an infrared light source is used, the infrared cut is unnecessary.

  The present invention has been made to solve the above-described problems, and is a contact image sensor that can accurately read image information without degrading the reading accuracy of color originals, particularly banknotes, securities and certificates, It is another object of the present invention to provide an image reading apparatus equipped with these.

The contact image sensor according to claim 1 converges light reflected from a multicolor light source having an infrared light source that irradiates two or more kinds of light including infrared rays to a document having a designated region that reacts to infrared light. An area corresponding to the width in the orthogonal direction of the designated area in a direction orthogonal to the moving direction of the original, between the lens to be received, a light receiving unit that receives light passing through the lens, and the original and the lens an outer to partially disposed permeate body, is characterized in that a document guide for supporting the transparent member.

The contact image sensor according to claim 2 converges light reflected from a multicolor light source having an infrared light source that irradiates two or more types of light including infrared rays to a document having a designated region that reacts to infrared light. The designated region in a direction orthogonal to the moving direction of the document, between the lens to be moved, a light receiving unit that receives light passing through the lens, a housing that houses at least the lens, and the document and the lens. a transmission member which is partially arranged outside the region corresponding to the width in the orthogonal direction, and characterized in that the transparent body is supported, and a document guide mounted detachably on the housing To do.

  According to a third aspect of the present invention, there is provided the contact image sensor according to the first or second aspect, wherein there are a plurality of the transmissive bodies corresponding to a plurality of designated areas of the document in the orthogonal direction.

  According to a fourth aspect of the present invention, there is provided the contact image sensor according to the first aspect, wherein the document guide is provided with a slit through which the light reflected from the document passes in the orthogonal direction, and the transmitting body partially covers the slit. It is a thing in any one.

  The contact image sensor according to a fifth aspect is the one according to any one of the first to fourth aspects, wherein the document is a securities or a banknote.

  According to a sixth aspect of the present invention, there is provided an image reading apparatus according to any one of the first to fifth aspects, wherein the contact image sensor according to any one of the first to fifth aspects is disposed on a front side and a back side of a document. Are matched.

  According to a seventh aspect of the present invention, there is provided an image reading apparatus according to the second aspect, wherein the contact image sensors according to the second aspect are respectively arranged on the front side and the back side of the document, and the optical axes of the light reflected from the document in each of the contact image sensors are matched. The housings of the contact image sensors are connected by a metal holder.

According to the invention of claims 1 to 5, and an area for reading the IR reading area and other character symbols, such as a bill separating, the effect of read IR, R, and G simultaneously high precision on a single unit .

According to the invention according to claim 4, since the slit in the reading direction of the document guide is provided in the contact image sensor according to any one of claims 1 to 3, a substance having a higher refractive index than air is not interposed in the middle, so that the optical path The length can be shortened and the defocus phenomenon at the time of IR reading can be improved.

According to the invention of claim 6 and claim 7, respectively disposed close adhesion image sensor on the front side and back side of the document, Ri combined optical axes of their reading position, the same metal plate housing of units in so fixed, the effect of preventing the factor deteriorating the reading accuracy by the apparatus (image reading apparatus such as a bill discriminator and matching machine).

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view of a contact image sensor according to Embodiment 1 of the present invention. In FIG. 1, 101 is a multicolor light source including an infrared (IR) light source, 2 is an erect image forming lens that collects light represented by a rod lens array, and 3 is light collected by the lens 2. A sensor IC that receives light and has a plurality of light receiving portions. 4 is a sensor substrate on which a plurality of sensor ICs 3 arranged linearly according to the reading width is mounted, 51 is a transparent glass, 6 is a housing for housing the light source 101, the lens 2 and the sensor substrate 4, and 7 is A connector for transferring input / output of an image reading signal and the like, 8 is a document such as a banknote, 9 is a transport platen (driving roller), and 10 is an infrared shielding paint installed on the inner surface of the glass 51. Reference numeral 101a denotes a light emitting portion of the light source 101. All light from the light source is radiated from the emitting portion 101a toward the document 8.

  The light emitted from the emission part 101 a of the light source 101 passes through the glass 51 and reaches the image part of the document 8. Light is absorbed in the black portion of the image, and light is appropriately reflected by the respective light sources in the color image. Nearly 100% of the light is reflected in the white part of the image. The light reflected by the original passes through the glass 51 again as scattered light, and part of the light passes through the region of the infrared light shielding paint 10, is collected by the lens 2, and enters the light receiving portion of the sensor IC 3 on the sensor substrate 4. The sensor IC 3 includes a plurality of light receiving units and a drive unit that photoelectrically converts light incident on each light receiving unit and extracts an output. The photoelectrically converted light is output as image information via the connector 7 as a serial signal. The platen 9 is rotated and the document 8 is conveyed to continuously read color images written on the document 8 for each line.

  In this embodiment, the light source 101 uses three light sources of IR (infrared), R (RED), and G (GREEN), and sequentially turns on at an interval of 0.1 ms to read an image. Reflected light for each light source is input to the light receiving unit as image information on the original surface. In this case, along with the chromatic aberration of the lens 2, the conjugate length (also referred to as optical path length) indicating the focal length from the sensor IC 3 which is a light receiving unit installed on the sensor substrate 4 to the document differs depending on the wavelength of each light source.

  In this embodiment, a sensor IC 3 having a resolution of 200 DPI is used. At that time, the conjugate length of the IR light source is 11.0, the conjugate length of the R light source is 9.6, and the conjugate length of the G light source is 9.0. Met. For this reason, the optical path length from the original to the light receiving portion is different in wavelength of each light, so that defocusing occurs in principle for two types of light. The cause of this is largely due to spherical aberration of the lens 2 as shown in FIG. 2 (defocus between the focal point of the light passing near the optical axis of the lens and the light passing through the outer periphery of the lens). In particular, since IR has an extremely long optical path length compared to other light source wavelengths, a defocus phenomenon occurs in a contact image sensor (hereinafter also referred to as a unit) in which the optical path length is set in the vicinity of the R light source and G light source assuming color reading. Becomes larger.

In such a case, by reducing the diameter of each rod-shaped lens bundle forming the rod lens array that is the lens 2, it is possible to compress the difference between the light source conjugate lengths. However, when the diameter is reduced, the effective transmitted light amount of the light passing through the lens 2 is greatly reduced, and there is a problem that the light amount is extremely reduced when the reflected light from the original enters the light receiving unit. As a result of experiments, when the diameter of a rod-shaped lens portion of a commercially available rod lens array is changed from 0.6φ to 0.3φ, the effective transmitted light amount becomes about 1/4. In such a case, since high-speed reading cannot be realized, it is better to maintain the diameter of the rod-shaped lens and prevent the defocus phenomenon.

  Accordingly, in this embodiment, the lens 2 having a rod-shaped lens diameter of 0.6φ is used, and the IR light directly incident on the lens 2 out of the scattered light reflected on the document surface is shielded (absorbed) from the periphery of the lens 2. The defocus phenomenon was improved by printing the infrared shielding paint 10 on the lower surface of the glass 51 along the light receiving portion of the sensor IC 3 in order to receive the incident IR light. Usually, an infrared shielding material (resin) is used to block the entire IR light, but in this embodiment, it is applied to only a part of the region. In this case, when a parallel light beam is irradiated with a spherical lens as shown in FIG. 2, the light incident from the periphery is focused through a long distance so that the imaging position is different. Accordingly, the reflection surface of the document or the like is set in advance, and the scattered light reflected by the document can be regarded as an image formed by wrapping light from the periphery apparently shortened by the glass 51 as compared with the direct light. This becomes effective light and improves the defocus phenomenon.

  FIG. 3 shows the relationship between the infrared light shielding area width and the MTF (Modulation Transfer Function) indicating the resolution at that time using the unit in this embodiment. The IR light source was divided into a low output and a high output in consideration of variations in luminance of the light source. In the case of high output (high luminance) irradiation, it can be seen that when the printing width of the infrared light shielding paint 10 applied to the glass 51 is about 0.3 mm, the MTF is improved about twice as compared with the case where the light shielding is not performed. It can also be seen that the same effect can be obtained even with low output (low luminance) irradiation. When the light-shielding width exceeds 0.3 mm, an abrupt decrease in MTF is observed. This is presumably because the effective amount of IR incident on the lens 2 is greatly reduced. Note that the thickness of the infrared light shielding paint 10 after sintering on the glass 51 is appropriately about 7 μm, and it is understood that the scattered direct light is sufficiently shielded.

  The measurement of MTF in this embodiment is intended to prevent tampering of banknotes (documents) such as banknote discriminators, and to detect the area of a printed part that reacts to IR rather than to read banknote characters. Since the reading resolution may be relatively low because it is mainly, measurement was performed with a test chart of 2 line pairs / mm (2 sets of black and white stripe patterns in 1 mm). Usually, the resolution of this type of MTF is considered to be 20% or more in the case of the light receiving element array having the resolution of 200 DPI of this embodiment, so an infrared light shielding width of 0.1 mm to 0.4 mm is appropriate. is there.

Embodiment 2 FIG .
FIG. 4 shows a glass 52 having a protrusion-shaped glass 53 bonded to the upper surface of the glass 52 as a protrusion. The glass 53 has a hemispherical projection shape, and is mounted on the glass 52 by applying the infrared light shielding paint 10 on the plane side. In this case, since a projection 53 is newly added between the reflected light from the original and the light receiving portion, the thickness of the glass 52 is reduced by the thickness of the projection 53, and the optical dimensions for R reading and G reading are maintained. .

  In the structure shown in the first embodiment, the infrared light shielding paint 10 is applied at the center position of the optical axis near the upper surface of the lens 2 through which the reflected light passes. The scattered direct light of IR light is shielded by the infrared light shielding region, but the amount of incident light of the sneak light from the periphery increases due to the focusing effect of the glass 53 and the refraction effect of the glass 52 which is a flat plate. . In addition, since these IR lights have passed through a long optical path with respect to the scattered direct light, they are set with other optical path lengths such as R and G (such as when the IR optical path length is set short). In the contact image sensor, it can be considered that the conjugate length becomes longer for IR light, so that it is considered that the effective light described in the first embodiment is further increased.

  FIG. 5 shows the MTF characteristics measured in this example. There is an overall improvement of about 5% over the MTF characteristics described in the first embodiment.

Embodiment 3 FIG.
In the first and second embodiments, the infrared light-shielding paint 10 is applied to the glass 51 or 53 and the structure design is adapted to the optical dimensions of R and G. However, the case where the infrared reading accuracy is further improved will be described. . The reflected light arrives at the light receiving portion via the lens 2, but the focal length becomes long even when the housing 6 of the same design is used by inserting the optical path length having a refractive index larger than that of air.

FIG. 6 describes the relationship between the focal position and the refractive index of the material. FIG. 6 plots the focal position when a substance is present in the middle of the path from the upper end of the lens to the focal position when determining the focal position located above the upper end of the lens 2 in FIG. Usually, when a substance is arranged in the optical path of light, the apparent focal length becomes longer than that of air due to the refractive index of the substance. That is, Δt = {(n−1) / n} · t
Here Delta] t: extension amount n: refractive index of the material t: If thickness of, for example, the refractive index of the material through which light passes is air 1.00, when the focal position was 2.1 from the lens 2 top, middle When a substance having a refractive index higher than that of air is present, the distance is longer than 2.1. If the refractive index of the glass is about 1.51, the focal position becomes 2.43 when 1 mm of glass is interposed, and the focal position extends about 0.33 compared to the case where nothing is interposed. .

  Also, the amount of extension differs with respect to the wavelength of light, and light having the same substance but having a longer wavelength has a smaller refractive index than light having a shorter wavelength. Longer ones have longer focal positions. Therefore, it can be seen that when there is glass interposition and the position of the document is set in advance, removing the glass leads to an improvement in resolution when reading the IR light source.

  That is, the RG is read from the upper surface of the glass intervening glass, and the IR-based contact image sensor and the RG-based contact image sensor can be selectively used by reading without IR glass during IR reading. Therefore, it is preferable that the contact image sensor has a structure in which the glass can be freely attached and detached. This is because a normal contact image sensor is bonded to the glass and the case and cannot be removed. This is because, in a unit without glass, it is normal that the glass is not considered in the design of the optical path length of the unit itself.

  By the way, in the case of a contact image sensor with glass addition, the position of the original surface can be inferred, and the glass surface can be used as a conveyance guide.

FIG. 7 shows the structure of a unit to which the glass 51 can be attached and detached. Reference numeral 12 denotes a conveyance guide having a structure in which the glass 51 is fixed and the conveyance guide itself is fixed by the housing 6. The conveyance guide 12 is made of plastic and has elasticity, so that it is easy to hold the glass and fix it to the housing. In the case of the present embodiment, since the conveyance guide is further added to the upper part of the glass, as shown in FIG. 8, the document reading portion of the conveyance guide has a space with a slit. This is because the inclusion of substances is removed in consideration of IR reading. Normal RG reading is performed on the upper surface of the conveyance guide 12, but in the case of an IR reading main body, the glass 51 can be removed as shown in FIG.

  With the configuration as described above, the glass can be removed during IR reading, and the focal position can be lowered as compared with the case where the glass 51 is present. Therefore, the IR defocus phenomenon can be improved.

Embodiment 4 FIG.
FIG. 10 is an imaginary view of a pattern of a bill as a manuscript. Usually, characters and designs of banknotes are read by RG, but a region that reacts to incidents other than visible light such as infrared rays and ultraviolet rays is partially installed on the banknotes. These readings are not all read, but only a designated area is usually read as appropriate. For example, when there are two infrared reaction regions shown in FIG. 10, one shape (region) may be read and the other may not be read. In such a case, the glass 51 only in the designated area is removed, and the glass 51 is installed in the other areas to perform IR, R, and G readings.

In the case of the present embodiment, since the glass 51 exists in the region to be read by R and G, the design and print number which are the original reading portions of R and G can be read with high accuracy. Further, FIG. 11 shows two glasses 54 that are not installed in the IR area of the reading area but are the glass 51 installed in an area other than the IR area . In this case, since the glass 51 is divided into two parts to read the two infrared reaction areas, it is possible to read a plurality of infrared reaction areas with high accuracy. If the reading performance of the image around the edge of the glass 54 is excluded, high-precision reading can be performed for almost all the designated areas. Further, in order to prevent an output change in image reading around the edge of the glass 54, it is preferable to stabilize the unnecessary output by applying a black coating on the corresponding slit portion of the conveyance guide 12 to absorb light. That is, a light absorption region is provided on both sides centering on the glass edge by a dimension corresponding to the thickness of the glass 54.

Embodiment 5 FIG.
In the third and fourth embodiments, the glasses 51, 52, 53 and the glass 54 are used as the transmissive bodies, but other materials can be applied as long as they are transparent. For example, a transparent crystal may be used as the transmission body. In the case of artificially produced transparent crystals, the refractive index is approximately 2.0. In this case, when a 1 mm transparent crystal is interposed, the focal position is 2.6 as shown in FIG. 6, and the focal position is extended as compared with a case where nothing is interposed by about 0.5. By removing the unit designed with the optical path length using the transparent crystal as the transmissive body, the IR can be read even if the document surface is further up. That is, since a large gap is generated between the conveyance guide 12 and the original, for example, even when there is an external glass (not shown) of a certain thickness in which the original is fixed with another glass or the like, IR reading is performed with high accuracy. It can be carried out. In particular, the unit drive type (moving because the unit itself reads) is useful because there is a gap margin when driven.

Embodiment 6 FIG.
In the example of the fifth embodiment, the transparent crystal is adopted as the transmission body. However, the iodine crystal is also a transparent body, the refractive index thereof is approximately 3.3, and the extension amount is 0.7 mm. Similarly, a refractive index of about 1.8 such as sapphire may be used as the transparent body. In addition, if the reading is relatively slow (IR: 0.25, R: 0.25 G: 0.25 ms in total, such as 0.75 ms / line), the light accumulation time of the light receiving unit will be long, so even low transmittance of turbid shaped relatively light translucent transparent member can be used.

  In addition, when the conveyance guide 12 is provided with a slit, the reading area is a space and the conveyance guide 12 does not need to be a transparent body or a translucent body, and may be a normal metal plate, but the conveyance guide 12 is made of glass. In addition, it is necessary to use a phosphor bronze plate (copper plate in which tin is contained in phosphorus) which is rich in elasticity and needs to be held by the housing 6.

  Alternatively, black paint may be baked on the copper plate to completely absorb light from each light source. In this case, only the effective light from the light source 101 (light reaching only in the slit) can be reflected even if the distance between the light emitting portion 101a of the light source 101 and the document surface changes, and therefore unnecessary light (flare light). ) And can be read with higher accuracy than the transparent conveyance guide 12.

Embodiment 7 FIG.
FIG. 12 shows the conveyance part of the banknote discriminator when reading both sides of a banknote with two units as a pair. The bill is transported along the transport guide 12 of the pair of units, but the reading optical axes of the units of the bill reading portion are combined. This is because the reading positions of the banknotes are different from each other only by making the units face each other, and there may be a case where no banknote exists in the reading portion of the other unit during one reading period. In that case, due to a phenomenon such as output overflow, noise is mixed during the reading period of one unit, and the reading accuracy is lowered. For this reason, the reading optical axes of the paired units are aligned, and it is ensured that there is a document on the other side during the reading period, and that the reading period is in progress.

  Further, in high-speed reading (IR: 0.1, R: 0.1, G: 0.1 ms in total 0.3 ms / line, etc.), the reference level of two units (for example, the output potential when the LED is OFF) (Also referred to as a reference) are preferably matched. That is, in order to match the reference levels of the two units with certainty, the potential floating due to external factors is made the same. For this reason, the units are connected by a metal holder integrated between the housings 6. The metal holder also connects its potential to the reference level of each unit. Normally, the reference levels of these units are adjusted in advance, so that even if they are affected by changes in the GND level of peripheral circuits such as banknote discriminators, there is no difference between the reference levels of the units, so a document can be read with high accuracy. Is possible.

  Further, when there is no reference level at the terminal of the connector 7 of the unit, the following effects can be obtained by commonly connecting the potential of the integrated metal holder to the GND potential of the connector 7 of each unit.

  There are IR, R, and G light source switching periods and blanking periods (periods during which no output is output) even during the reading period of one line. When the light source is switched, the output line fluctuates due to changes in the power supply level and the reading accuracy deteriorates. To do. Further, during the blanking period, the output line is in a high impedance state, and there is a large level (blanking level) fluctuation, which is easily affected by noise. Reading accuracy can be ensured for the above problems. In particular, when the level of the blanking period of the output line is referred to as a reference level, reading with higher accuracy is possible, which is a great effect.

  In the embodiment of the present invention, three types of light sources of IR: R: G are used instead of R, G, and B as light source types. However, in order to perform reading with a normal RGB light source, a light source is added with a B light source. There may be four types, and another light source having a shorter wavelength than IR, such as an ultraviolet light source, may be added.

  In the embodiment of the present invention, the improvement due to the difference in the conjugate length from the center position of the lens 2 to the upper document surface among the conjugate lengths of the lens 2 which is a rod lens array has been described. However, as shown in FIG. No mention is made of the conjugate length from the light receiving position to the light receiving position. However, as shown in FIG. 9, in the case of the embodiment of the present invention, the sensor substrate 4 is fitted in the housing 6, and adjustment from the center of the lens 2 to the light receiving portion is performed by moving the sensor substrate 4 up and down. The structure can be changed. That is, when it is desired to extend the center position of the lens 2, it can be easily changed by adding a desired padding to the contact portion between the sensor substrate 4 and the housing 6. In this case, the sensor substrate 4 and the housing 6 are Affixed and fixed entirely or partially with tape (not shown).

  In FIG. 9, the sensor IC 3 is usually coated with a resin 13 for protecting the IC with a thin film. Normally, this thickness is optically negligible, but by increasing the thickness of the resin 13, the optical path length of the lens 2 and the light receiving portion can be extended.

  That is, in this embodiment, it is preferable to coat the transparent silicon resin with a thickness of about 1.85 mm in consideration of the thickness (0.35 mm) of the sensor IC 3 and the height of the connection line (wire bond metal line). In this case, the thickness related to the conjugate length of the silicon resin is 1.5 mm. If the refractive index of the resin 13 is 1.4, the extension amount is 0.43. In this case, the optical path length can be extended. is there.

It is sectional drawing of the contact | adherence image sensor by Embodiment 1 of this invention. It is a figure explaining spherical aberration, such as a spherical lens. It is a figure explaining the infrared ray shielding width of the contact | adherence image sensor by Embodiment 1 of this invention, and the relationship of MTF. It is sectional drawing of the contact | adherence image sensor by Embodiment 2 of this invention. It is a figure explaining the relationship between the infrared rays light-shielding width of the contact | adherence image sensor by Embodiment 2 of this invention, and MTF. When a substance exists between an original and a lens, it is a figure explaining the change of the focus position of a lens by the refractive index of these substances. It is sectional drawing of the contact | adherence image sensor by Embodiment 3 of this invention. It is a top view of the contact | adherence image sensor by Embodiment 3 of this invention, and is a figure explaining the conveyance of a document and the slit position on a document guide. It is sectional drawing when the glass of the contact | adherence image sensor by Embodiment 3 of this invention is removed. It is a figure explaining reading areas, such as a bill. It is sectional drawing of the contact | adherence image sensor by Embodiment 4 of this invention. It is a figure explaining the conveyance mechanism of two contact | adherence image sensors and image reading apparatus of Embodiment 7 of this invention. It is a metal plate which fixes two contact | adherence image sensors of Embodiment 7 of this invention.

DESCRIPTION OF SYMBOLS 1 Light source, 2 Lens, 3 Sensor IC, 4 Sensor board | substrate, 51 Glass, 52 Glass (thin type), 53 Glass (hemisphere), 54 Glass, 6 Case, 6a Tapping hole, 7 Connector, 8 Original, 9 Platen, DESCRIPTION OF SYMBOLS 10 Infrared light shielding paint, 11 Electronic component, 12 Document guide, 12a Slit, 13 Resin, 15 Metal holder, 16 Mounting hole, 101 Light source, 101a Injection | emission part.

Claims (7)

A multicolor light source having an infrared light source that irradiates two or more kinds of light including infrared rays on a document having a designated area that reacts to infrared light, a lens that converges light reflected from the document, and light that passes through the lens a light receiving portion for receiving, a between the document and the lens, in the direction perpendicular to the moving direction of the original, partially disposed outside the region corresponding to the width in the perpendicular direction of the designated area A contact image sensor comprising a transmissive body and a document guide that supports the transmissive body. A multicolor light source having an infrared light source that irradiates two or more kinds of light including infrared rays on a document having a designated area that reacts to infrared light, a lens that converges light reflected from the document, and light that passes through the lens A region that corresponds to the width of the designated region in the orthogonal direction in a direction orthogonal to the moving direction of the document, between the light receiving unit that receives light, a housing that houses at least the lens, and the document and the lens. and a transmitting body that is partially disposed outside the transparent member is supported, contact image sensor and a document guide mounted detachably on the housing.   The contact image sensor according to claim 1, wherein a plurality of the transmissive bodies correspond to a plurality of designated areas of the document in the orthogonal direction.   The contact image sensor according to claim 1, wherein the document guide is provided with a slit in the orthogonal direction for allowing light reflected from the document to pass therethrough, and the transmissive member partially covers the slit.   The contact image sensor according to claim 1, wherein the document is a securities or a banknote.   An image reading apparatus in which the contact image sensors according to any one of claims 1 to 5 are arranged on the front side and the back side of a document, respectively, and the optical axes of light reflected from the document are matched with each of the contact image sensors.   The contact image sensor according to claim 2 is arranged on each of the front side and the back side of the document, the optical axes of light reflected from the document in each of the contact image sensors are matched, and each housing of each of the contact image sensors An image reading device with a metal holder.

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