JP5606350B2 - Light guide unit and image reading apparatus - Google Patents

Description

  The present invention relates to a light guide unit used in a facsimile, a copier, a scanner, and the like, and an image reading apparatus including the light guide unit.

  In general, an illuminating device provided in an image reading apparatus or the like that illuminates an object to be read is a rod-shaped light guide member that guides light toward the object to be read so that light from the light source is efficiently irradiated to the object to be read. Is used. The light guide member has a light emitting portion that emits light, and a scattering region on a surface facing the light emitting portion, and the light incident from the light source on the end portion of the light guide member is transmitted to the light guide member. The light is guided in the main scanning direction, diffused and reflected in the scattering region, and emitted as linear light from the light emitting part. In this way, the illumination device having the light guide member illuminates the reading target area.

  For example, Patent Document 1 discloses an illumination device for a backlight such as a liquid crystal television, and a light guide member provided in the illumination device has a scattering region in which a milky white and linear irregular reflection part is formed on one surface thereof. In this illuminating device, the light quantity distribution with uniform brightness is realized by changing and adjusting the interval of the linear irregular reflection portions.

JP-A-3-201304

  However, in the illuminating device of Patent Document 1, it is necessary to adjust the interval of the irregular reflection portions many times in order to realize a uniform light quantity distribution, and the light guide member must be remade from the mold each time. Don't be. Therefore, the illumination device of Patent Document 1 has a problem that it takes time and cost to manufacture the light guide member.

  The present invention has been made to solve such problems, and provides a light guide unit that is easier to manufacture than conventional light guide members, and an image reading apparatus including the light guide unit. The purpose is to do.

In order to achieve the above object, the present invention is configured as follows.
That is, the light guide unit according to an aspect of the present invention is provided in an image reading apparatus that reads an image of a linear reading target portion along the main scanning direction of the reading target, and guides light to the reading target portion. The light guide unit includes a rod-shaped main body member formed of a transparent material and extending in the main scanning direction, and a light control member arranged to face the main body member along the main scanning direction. The main body member is directly formed along the main scanning direction on the light emitting surface for emitting the light to be irradiated to the reading target portion and the opposing surface facing the light emitting surface, and is incident on the main body member from the light source. A light scattering region that scatters light, and the light control member is disposed along the main scanning direction so as to face the light scattering region on the opposite surface side of the main body member, and transmits the light scattering region Has an absorption reflection pattern that absorbs and reflects light And wherein the door.

  According to the light guide unit in one aspect of the present invention, the light guide unit includes a main body member and a light control member, and a light scattering region is directly formed on the main body member, and the light control unit is opposed to the light scattering region. The absorption reflection pattern of the optical member was arranged. Therefore, the illuminance distribution of the reading target portion that cannot be dimmed in the light scattering region can be adjusted and uniformed by the absorption reflection pattern of the dimming member. At this time, it is possible to adjust and equalize the illuminance distribution simply by changing the absorption / reflection pattern of the light control member, and there is no need to remanufacture the light guide member as in the past, and the illuminance distribution is simpler than before. Can be adjusted in a short time and at low cost.

1 is a perspective view of an image reading apparatus according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of the image reading apparatus taken along line A-A ′ shown in FIG. 1. FIG. 2 is a schematic assembly diagram of the image reading apparatus shown in FIG. 1. It is sectional drawing in the edge part of the light guide part shown in FIG. 1, and is the figure explaining the mode of propagation of the light in a main body member. It is a block diagram for demonstrating operation | movement of the image reading apparatus shown in FIG. FIG. 2 is a diagram for explaining a schematic optical path in the image reading apparatus shown in FIG. 1. It is the figure which showed the mode of the light reflected in the light-scattering area | region in the main body member of the light guide part shown in FIG. It is a figure which shows the path | route of the light which permeate | transmitted the light-scattering area | region in the main body member of the light guide part shown in FIG. 1, and was reflected with the reflecting material. 2 is a graph showing a light amount distribution in a main scanning direction in a document when a light reflectance member and a low light reflectance member are used for the light control member shown in FIG. 1. It is a figure which shows the example of the absorption reflection pattern which can be provided with respect to the light modulation member shown in FIG. FIG. 7 shows an absorption reflection pattern of a light control member provided in an image reading apparatus according to Embodiment 2 of the present invention, a light amount distribution graph in a document before using the absorption reflection pattern, and a light amount distribution graph after use of the absorption reflection pattern. FIG. It is a perspective view of the base member of the housing | casing with which the image reading apparatus in Embodiment 3 of this invention is equipped, A base member is a member with a high light reflectance, and is a figure which shows having arrange | positioned the black pattern as an absorption reflection pattern. . It is a figure which shows the modification of the absorption reflection pattern provided in the base member shown in FIG. 12, and is a figure which shows the example of the black-and-white pattern which cut out a part of tape with low light reflectance.

  A light guide unit that is an embodiment of the present invention and an image reading apparatus including the light guide unit will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.

Embodiment 1 FIG.
With reference to FIG. 1, the image reading apparatus 101 provided with the light guide part 2 in Embodiment 1 of this invention is demonstrated. In FIG. 1 and the like, the minor axis direction Y is the left-right direction on the paper surface and corresponds to the feed direction of the document 1 and is also called the sub-scanning direction. The direction X is perpendicular to the direction Y and is the depth direction of the paper surface, and is also called the main scanning direction. The direction Z is perpendicular to the direction X and the direction Y and is the vertical direction of the paper surface, and is also referred to as a reading depth direction.

  The image reading apparatus 101 is also called a contact image sensor or CIS, and includes a light guide unit 2, a light source 11, and a reading unit 40 as basic components. In such an image reading apparatus 101, the light emitted from the light source 11 passes through the light guide unit 2, and the linear reading target portion 1 a along the main scanning direction in the reading target object (corresponding to the following document 1). The reading unit 40 reads the image of the reading target portion 1a. In addition, as shown in FIG. 1, the image reading apparatus 101 has two light guides 2 parallel to each other in the main scanning direction in a casing extending in the main scanning direction and having an upper surface formed of a transparent member. The light source 11 is disposed at the end 2 c of each light guide unit 2, the reading optical system 5 is disposed between each light guide unit 2, and the reading unit 40 is disposed below the reading optical system 5. , Having a schematic configuration. Hereinafter, each component of the image reading apparatus 101 will be described in more detail.

  The document 1 shown in FIGS. 1 and 2 corresponds to an object to be read, and is, for example, a read medium (irradiated object) that is an image information body of banknotes, securities, and other general documents.

  The transparent body 3 that forms the upper surface of the housing 9 of the image reading apparatus 101 forms a transport path for the original 1 and also serves to prevent entry of foreign matter into the apparatus, and is made of a transparent resin such as acrylic or polycarbonate. It is comprised with a material or a transparent glass material. Further, the transparent body 3 irradiates the document 1 with light emitted from the light emitting surface 2a of the main body member 21 constituting the light guide unit 2 which will be described in detail later, and transmits the light reflected by the document 1 to read optical. Incident into the system 5.

  FIG. 3 is an assembly development view of the image reading apparatus 101 according to the first embodiment. In FIG. 3, the LED holders 10 are disposed at both ends of the light guide unit 2, house the light source 11, and make light emitted from the light source 11 enter the main body member 21 of the light guide unit 2. In the present embodiment, the light source 11 has an LED chip. The LED holder 10 may be configured to be disposed only at one end 2c of the light guide unit 2.

  In the first embodiment, the light guide unit 2, the sensor IC 4 included in the reading unit 40, and the reading optical system 5 are equivalent to the effective reading width of the document 1 in the main scanning direction (effective reading width in the main scanning direction). It is configured or arranged over the above length.

  FIG. 4 is a cross-sectional view of a main part around the end 2c of the light guide unit 2. As shown in FIG. 4, the light source 11 is composed of an LED chip or the like, and normally emits visible light, infrared light, ultraviolet light, or the like. The light source 11 is mounted on the substrate 12, and an electrode pattern or the like for driving the light source 11 is formed on the substrate 12. Electric power to the light source 11 is supplied from the outside via an external connector 8 provided on the sensor substrate 6 constituting the reading unit 40.

  As shown in FIG. 4, the light emitted from the light source 11 enters the main body member 21 of the light guide 2 and reflects the inside of the main body member 21 while in the main scanning direction, that is, the document 1 transport direction (sub-scanning direction). ) In the orthogonal direction.

  The reading optical system 5 is configured such that the reflected light reflected from the reading target portion 1a in the document 1 is incident from the optical axis direction, and converges the reflected light. In the present embodiment, the reading optical system 5 is formed by a rod lens array.

The reading unit 40 includes a sensor IC 4, a sensor substrate 6, a signal processing IC 7, and an external connector 8.
The sensor IC 4 is a sensor that receives the light converged by the reading optical system 5 and photoelectrically converts it to output an electrical signal. The sensor IC 4 is equipped with a photoelectric conversion unit composed of a semiconductor chip or the like, other drive circuits, and the like. Yes.
The sensor substrate 6 is a substrate on which the sensor IC 4 and other electronic components are placed.
The signal processing IC 7 is a circuit portion that performs signal processing on the photoelectric conversion output from the sensor IC 4, and is configured by an ASIC (Application Specic Integrated Circuit) that performs signal processing in conjunction with the CPU and RAM, along with other electronic components. Placed on the substrate 6.
The external connector 8 is a connector used for an input / output signal interface including the photoelectric conversion output of the sensor IC 4 and its signal processing output.

  The housing 9 of the image reading apparatus 101 is made of metal or plastic that houses or holds the light guide unit 2, the reading optical system 5, and the reading unit 40. As shown in FIGS. 1 to 3, the housing 9 includes a plate-like base member 9 a extending in the main scanning direction. On the upper surface of the base member 9a facing the transparent body 3, two recesses that are formed in parallel with the main scanning direction and that are semicircular grooves are formed in the present embodiment. Are arranged, and the reading optical system 5 is arranged between the light guides 2. In addition, the sensor substrate 6 constituting the reading unit 40 is installed facing the upper surface of the base member 9a.

Next, the light guide 2 that is one of the characteristic parts in the image reading apparatus 101 of the present embodiment will be described.
The light guide unit 2 includes a main body member 21 and a light control member 22.
The main body member 21 is a bar-like transparent member extending in the main scanning direction, and in the present embodiment, has a cylindrical shape, and is incident from the light source 11 to the linear reading target portion 1 a along the main scanning direction in the document 1. It is a member that irradiates the light. The main body member 21 has a light emitting surface 2a and a light scattering region 2b. The light emitting surface 2a is an area for emitting light incident from the light source 11 from the inside of the light guide 2 to the reading target location 1a, and extends in the main scanning direction. The light scattering region 2b is a region directly formed along the main scanning direction on the opposite surface of the main body member 21 that faces the light emitting surface 2a, and scatters light incident into the main body member 21 by the light source 11. It is an area. In addition, when using the column-shaped main body member 21 like this embodiment, since the outer peripheral surface is a curved surface and is not flat, a part of outer peripheral surface may be shaved and planarized, and the light-scattering area | region 2b may be formed. .

  The light scattering region 2b will be described in more detail. The light scattering region 2b has a form in which a light reflective paint such as a white pigment is applied to a formation region in the main body member 21, a roughened form, a sawtooth prism-shaped form, or a pyramidal embossed form. It can be configured as a processed form. In particular, in the form using prism shape processing or emboss shape processing, the body member 21 can be integrally formed at the same time.

  In general, in the case of illumination in which light enters from the end of a rod-shaped light guide member, when the light reflectance of the scattering region is configured uniformly along the extending direction (main scanning direction) of the light guide member The amount of light incident on the scattering region near the light source increases, and the amount of light decreases as the distance from the light source increases. For this reason, in the light amount distribution irradiated on the reading object, the light amount becomes high at the end of the light guide member, and the uniformity of the light amount cannot be obtained in the main scanning direction.

Therefore, in the present embodiment, the light scattering region 2b adjusts the light reflectance along the main scanning direction from the end 2c, and creates a uniform light amount distribution in the main scanning direction. Specifically, for example, the coating range of the paint in the light scattering region 2b of the end 2c is reduced, and in the case of a prism configuration, the prism interval is widened to increase the light reflectance in the light scattering region 2b of the end 2c. In the case of a prism configuration, the light reflectance is increased by lowering and increasing the coating range toward the center of the main body member 21 in the main scanning direction.
With this configuration, the light reflectance of the light scattering region 2b is gradually increased from the end 2c of the main body member 21, and the light reflectance of the light scattering region 2b farthest from the light source 11 is maximized. By adjusting, a uniform light amount distribution is formed.

  In addition, when the light scattering region 2b is formed by prism shape processing, a member (reflecting material) having a high reflectance such as a white resin, a metal block, or a tape is placed under the prism processing to transmit the light scattering region 2b. The reflected light is reflected in the direction of the original 1 to increase the amount of light.

Next, the light control member 22 of the light guide unit 2 will be described.
The dimming member 22 is a member disposed to face the main body member 21 along the main scanning direction, and in particular, is a member disposed to face the light scattering region 2b. In the present embodiment, since the main body member 21 has a cylindrical shape as described above, the light control member 22 is a half obtained by dividing a pipe concentric with the main body member 21 in half along the longitudinal direction as illustrated. Cylindrical shape. Such a light control member 22 has the absorption reflection pattern 23 (FIG. 10) which absorbs and reflects the light which permeate | transmitted the light-scattering area | region 2b to the exterior of the main body member 21 from the light-scattering area | region 2b. By having the absorption reflection pattern 23, the amount of light transmitted through the light scattering region 2b can be adjusted again into the main body member 21, and the uniformity of the amount of light emitted from the main body member 21 in the main scanning direction can be adjusted. Can be obtained. In addition, in this embodiment, although the structure which provides the absorption reflection pattern 23 in the light modulation member 22 is taken, the light modulation member 22 itself may comprise the absorption reflection pattern 23. FIG. The absorption reflection pattern 23 will be described in detail below.

Furthermore, the light control member 22 is demonstrated with reference to FIGS. 7-10.
First, the reflection of light at the light scattering region 2b will be described. FIG. 7 shows main light paths i and light paths ii in which light is directly reflected by the light scattering region 2b having a triangular cross section. In the light path i, light enters the light scattering region 2 b from the inside of the main body member 21, undergoes total internal reflection twice in the light scattering region 2 b, and then goes from the light emitting surface 2 a of the main body member 21 to the outside of the main body member 21. This is an outgoing optical path. In the light path ii, light enters the light scattering region 2b from the inside of the main body member 21, passes through the light scattering region 2b, refracts and exits once into the air layer, and then enters the light scattering region 2b again. This is an optical path that is transmitted through and then totally reflected by the light scattering region 2b and emitted from the light exit surface 2a.

  FIG. 8 is a diagram illustrating a state in which light is transmitted through the light scattering region 2b. As shown in the figure, since light is transmitted also in the light scattering region 2b, the efficiency of illumination deteriorates unless this transmitted light is used. Therefore, generally, a reflecting material for returning transmitted light is provided under the light scattering region. The reflecting material may be any material having a high light reflectance such as a white paint, a white resin, a metal surface, or a metal tape. FIG. 8 illustrates an example in which a white resin material that scatters and reflects light as a reflective material is disposed below the light scattering region. The light scattered and reflected by the white resin material is reflected by various optical paths, passes through the light scattering region 2b, returns into the light guide member, and is emitted from the emission surface.

  As described above, when a prism is used as the light scattering region, the light quantity uniformity in the main scanning direction is ensured by adjusting the interval between the prisms. However, an actual light guide member often cannot obtain a light amount distribution as designed due to manufacturing errors, light distribution of a light source, and the like. As already explained, conventionally, the prism interval is adjusted again in consideration of errors to ensure the uniformity of the light quantity distribution in the main scanning direction. However, re-adjustment of the prism requires a rework of the mold and the cost. And took time.

Therefore, in the present embodiment, the light control member 22 is provided so as to face the light scattering region 2b of the main body member 21 of the light guide unit 2, and light transmitted through the light scattering region 2b is adjusted by the light control member 22 of the main body member 21. The amount of light emitted from the light exit surface 2a is adjusted, and the illuminance distribution in the reading target portion 1a along the main scanning direction of the document 1 is made uniform.
In the present embodiment, a method of adjusting the amount of reflected light in the light control member 22 is a part of the light control member 22 that is replaced with a low light reflectivity member such as black printing or a black resin material, or a low light reflectivity member. Is performed on the light control member 22. The procedure for determining the low light reflection area on the light control member 22 is as follows.

  First, a light amount distribution irradiated on the original 1 when a light control member having a uniform high light reflectance, for example, a white light control member 22 is installed is measured as A (white). In addition, when a light control member having a uniform low light reflectance, for example, a black light control member 22 is installed, the light quantity distribution irradiated onto the document 1 is A (black), and two kinds of measurements are performed.

  Next, for each measurement result, the measured light quantity distribution is divided along the main scanning direction, and the average light quantity for each divided area is compared as An (white) and An (black), respectively. The ratio of the area to the low light reflection area is calculated. FIG. 9 shows an average light amount distribution for each divided region. Here, n represents the number of the divided area, and n = 0 corresponds to the center of the main body member 21 in the main scanning direction. Note that the amount of light can be adjusted more finely if the number of divisions in the main scanning direction is made finer, but the limit of the number of divisions is determined in consideration of the installation accuracy of the low light reflection region. In the first embodiment, the illuminance distribution is adjusted by setting the divided region to 1 cm in the main scanning direction. The area ηn to which black for each divided region of the light control member 22 is tightened is determined by the following equation. The area ratio between white and black may be finely adjusted according to the target characteristics.

  FIG. 10 shows a configuration example of the absorption reflection pattern 23 in the light control member 22. The absorption reflection pattern 23 of “No. 1” is a pattern formed by straight lines parallel to the sub-scanning direction, and the absorption reflection pattern 23 of “No. 2” is a pattern formed by oblique lines. .3 "absorption reflection pattern 23 is a pattern formed by black dots. These are merely examples, and the absorption / reflection pattern 23 may be formed in any pattern as long as the areas of white and black satisfy the above-described formula. In the first embodiment, the absorption reflection pattern 23 is produced by printing black on a white tape. However, the absorption reflection pattern 23 may be formed on a resin or metal plate or tape.

  Further, when the base member 9 a (FIG. 1) of the housing 9 of the image reading apparatus 101 is made of a member having a high light reflectance such as white resin or metal, a member having a high light reflectance as the light control member 22. There is no need to prepare. That is, a transparent member may be prepared as the light control member 22 and a black pattern may be printed thereon to make the light amount distribution on the document surface uniform. Alternatively, by arranging a plurality of light control members colored in black or gray along the main scanning direction and adjusting the arrangement interval at this time, the absorption reflection pattern 23 is formed by the light control members 22 themselves. You can also.

  On the other hand, when the housing 9 is made of a low light reflectance member such as a black resin, a member such as a transparent resin or glass is prepared as the light control member 22, and the original is printed by printing a white pattern. The light amount distribution on the surface may be made uniform.

The operation of the image reading apparatus 101 according to the first embodiment configured as described above will be described below.
Light incident on the main body member 21 of the light guide unit 2 from the light source 11 propagates in the main body member 21 in the main scanning direction, is scattered by the light scattering region 2b of the main body member 21, and is emitted from the light emitting surface 2a. . At this time, the light emitted from the light emitting surface 2a is emitted with uniform brightness or intensity in the main scanning direction of the document 1 because the light guide unit 2 includes the light control member 22 as described above.

The light emitted from the light emitting surface 2 a is applied to the reading target portion 1 a of the document 1, and the reflected light reflected by the reading target portion 1 a is received by the sensor IC 4 through the reading optical system 5.
The sensor IC 4 converts light into an electrical signal according to light intensity by photoelectric conversion. The electric signal is subjected to various signal processing by the ASIC 7 or the like on the sensor substrate 6 and is finally output as an image signal of the document 1 from the external connector 8 to the outside of the apparatus.

  FIG. 6 is a schematic explanatory diagram of an optical path in the image reading apparatus 101. That is, FIG. 6 shows that the light emitted from the light emitting surface 2a of the main body member 21 of the light guide unit 2 is applied to the reading target portion 1a of the document 1, and the reflected light passes through the reading optical system 5 and passes through the sensor IC 4. The optical path leading to is shown. In FIG. 6, the light incident on the main body member 21 is scattered and reflected by the light scattering region 2 b of the main body member 21, and part of the light is emitted from the light emitting surface 2 a of the main body member 21 and refracted by the transparent body 3. Then, the portion 1a to be read of the document 1 is irradiated. The irradiation angle from the main body member 21 to the document 1 is emitted from the light emitting surface 2a at an irradiation angle C determined by the extension line connecting the light scattering region 2b and the light emitting surface 2a and the optical axis of the reading optical system 5. To.

  FIG. 5 is a block diagram for explaining the operation of the image reading apparatus 101. The light receiving unit provided in the sensor IC 4 has the timing of the start signal (SI) synchronized with the clock signal (CLK) of the CIS (Contact Image Sensor) in synchronization with the system clock (SCLK) of the timing generator. A photoelectrically converted analog output (SO) is obtained. The analog output (SO) is converted from analog to digital (A / D) by the ASIC 7, and the signal processing circuit performs shading correction including sample and hold, all bit correction, and the like. To correct the signal data, data is collected from the RAM area storing the signal data and the RAM area storing the reference data, and is processed. The CPU, RAM, and signal processing circuit of the ASIC 7 are collectively referred to as a signal processing unit.

  As described above, according to the image reading apparatus 101 of the first embodiment, the light guide unit 2 is separated into the main body member 21 and the light control member 22, and the light reflection member 22 is provided with the absorption reflection pattern 23. It was. Therefore, when the light amount distribution is corrected, it is only necessary to change the absorption / reflection pattern 23, and it is not necessary to remanufacture the entire light guide member from its mold as in the prior art. Therefore, it is possible to make the illumination distribution in the main scanning direction uniform in a shorter time and at a lower cost than in the past.

Embodiment 2. FIG.
In the second embodiment, only the configuration of the absorption reflection pattern 23 in the light control member 22 is different from the configuration in the first embodiment, and the other configuration in the image reading apparatus in the second embodiment is the same as in the first embodiment. The configuration is the same as that of the image reading apparatus 101 of FIG. Therefore, only the structure of the absorption / reflection pattern in the second embodiment will be described below.

  As shown in FIG. 11, the absorption / reflection pattern 24 provided in the image reading apparatus according to the second embodiment includes an absorption / reflection pattern 24a having a monochrome pattern as described in the first embodiment and an absorption / reflection pattern 24b having only black. Have. Such an absorbing / reflecting pattern 24 is provided in the light control member 22.

  As described above, the light amount distribution in the main scanning direction in the main body member 21 of the light guide unit 2 may not actually be as designed. That is, when the light amount distribution in the document 1 is measured with the light control member 22 having a uniform high light reflectance facing the light scattering region 2b of the main body member 21, a part of the light amount in the main scanning direction is high. Suppose that a location exists. In this case, the black absorption / reflection pattern 24 or the black / white absorption / reflection pattern 24 is arranged only in correspondence with the light scattering region 2b corresponding to the high light quantity portion. As a result, the illuminance in the main scanning direction of the document 1 can be made uniform. On the other hand, when a part of the light amount on the original 1 is low, a black absorption reflection pattern 24 or a black and white absorption reflection pattern 24 corresponding to only the light scattering region 2b corresponding to a region other than the low light amount region is provided. By arranging, the illuminance can be easily made uniform. Therefore, such an absorption / reflection pattern 24 can be said to be an illuminance uniformizing unit because the illuminance is uniformized.

  As described above, in the image reading apparatus according to the second embodiment, in addition to the effects achieved by the image reading apparatus 101 according to the first embodiment, the illuminance can be easily equalized when the light amount is high or low in only a part of the light amount distribution. The effect that it can aim at can be acquired.

Embodiment 3 FIG.
In the image reading apparatus according to the third embodiment, the base member 9a of the housing 9 is made of a member having a high light reflectance such as white resin or metal, and conversely, a member having a low light reflectance such as a black resin. It has the composition which is. Other configurations are the same as those of the image reading apparatus 101 according to the first embodiment.

  In the case of the image reading apparatus according to the third embodiment, the absorption reflection pattern 23 is produced by applying, for example, a paint having a high light reflectance or a paint having a low light reflectance to the base member 9a itself. Thereby, the light quantity distribution in the main scanning direction in the main body member 21 of the light guide 2 can be made uniform. FIG. 12 shows an example in which a low light reflectance pattern is formed on the base member 9a coated with a paint having a high light reflectance.

  A base having a low light reflectivity or a high light reflectivity is formed by cutting out a part of a tape having a high light reflectivity or a low light reflectivity to form an absorption reflection pattern 23 and facing the light scattering region 2b of the main body member 21. It may be installed on the member 9a to make the light quantity uniform. FIG. 13 shows an example in which an absorption reflection pattern 23 is formed by cutting out a part of a tape having a low light reflectance. By providing such an absorption reflection pattern 23 on the base member 9a having a high light reflectance, the reflectance of the light transmitted through the light scattering region 2b is adjusted, and the uniformity of the light quantity in the main scanning direction is ensured. be able to.

  As described above, in the image reading apparatus according to the third embodiment, the base member 9 a itself also serves as the light control member 22. Therefore, in the image reading apparatus according to the third embodiment, in addition to the effect exhibited by the image reading apparatus 101 according to the first embodiment, an effect that the number of component parts of the image reading apparatus can be reduced can be obtained.

  Further, the configuration of the image reading apparatus of the third embodiment and the configuration of the image reading apparatus of the second embodiment may be combined.

DESCRIPTION OF SYMBOLS 1 Document, 2 Light guide part, 2a Light emission surface, 2b ... Light scattering area | region, 9 Housing | casing, 11 Light source, 21 Main body member, 22 Dimming member, 23, 24 Absorption reflection pattern,
24b Illuminance equalization unit, 40 reading unit,
101 Image reading apparatus.

Claims (4)

Provided in an image reading apparatus that reads an image of a linear reading target portion along a main scanning direction in a reading target, and a light guide unit that irradiates light to the reading target portion,
The light guide unit includes a rod-shaped main body member formed of a transparent material and extending in the main scanning direction, and a light control member arranged to face the main body member along the main scanning direction,
The body member is
A light exit surface that emits light that irradiates the reading target location;
A light scattering region that is directly formed in the main scanning direction on the facing surface facing the light emitting surface and scatters light incident on the main body member from the light source, and
The light control member is
The main body member has an absorption reflection pattern that is disposed along the main scanning direction so as to face the light scattering region on the opposite surface side of the main body member, and absorbs and reflects light transmitted through the light scattering region. It is composed of divided areas divided into three or more along the main scanning direction, each divided area has a different light absorption rate, and the light absorption rate is the illuminance in the main scanning direction irradiated to the reading target portion The distribution is set to be uniform,
A light guide section characterized by that.   The light control member further includes an illuminance uniformizing unit, and the illuminance uniforming unit is provided in a part of the absorption / reflection pattern and only absorbs or reflects light transmitted through the light scattering region. The light guide described.   3. The light guide unit according to claim 1, wherein the absorption reflection pattern faces a light scattering region of the main body member and is provided in a housing of the image reading apparatus. The light guide unit according to any one of claims 1 to 3,
A light source that makes light incident on an end portion of a main body member constituting the light guide portion;
A reading unit that reads an image at a linear reading target portion along the main scanning direction in the reading target, irradiated with light emitted from the light guide unit;
An image reading apparatus comprising:

Images