ILLUMINATION APPARATUS, LINE SENSOR ASSEMBLY, READING APPARATUS, AND PRINTING APPARATUS

There is provided with an illumination apparatus. The illumination apparatus includes a light source. A rod-shaped light guide includes, as a first surface, a light emitting surface that emits light taken from the light source. A light guide cover is configured to cover a second surface different from the first surface among surfaces of the light guide. The second surface is a surface extending in a longitudinal direction of the light guide. The light guide cover is extended in the longitudinal direction. The light guide cover includes at least one finger holding the light guide.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an illumination apparatus, a line sensor assembly, a reading apparatus, and a printing apparatus.

Description of the Related Art

As an illumination apparatus for a reading apparatus that uses a line sensor, there is known an apparatus that irradiates a linear irradiation region with light from a point light source using a rod-shaped light guide. For example, according to Japanese Patent Laid-Open No. 2014-033440, light sources are respectively arranged at two ends of a rod-shaped light guide, light beams entering the light guide from the two end faces of the light guide in a longitudinal direction exit from the side surface of the light guide extending in the longitudinal direction, and a reading target is irradiated with the light beams. The light guide includes a light diffusing surface that extends in the longitudinal direction and diffuses light, and an emitting surface that extends in the longitudinal direction and emits light toward the reading target. Furthermore, a light guide cover is attached to the light guide to improve the use efficiency of light. The light guide cover covers the light diffusing surface of the light guide, and reflects light externally emitted from the light diffusing surface to enter the light guide.

SUMMARY OF THE INVENTION

According to an embodiment of the present invention, an illumination apparatus comprises: a light source; a rod-shaped light guide including, as a first surface, a light emitting surface that emits light taken from the light source; and a light guide cover configured to cover a second surface different from the first surface among surfaces of the light guide, wherein the second surface is a surface extending in a longitudinal direction of the light guide, wherein the light guide cover is extended in the longitudinal direction, and wherein the light guide cover includes at least one finger holding the light guide.

DESCRIPTION OF THE EMBODIMENTS

In the arrangement described in Japanese Patent Laid-Open No. 2014-033440, to assemble a light guide and a light guide cover, it is necessary to insert the light guide into the light guide cover along the longitudinal direction. This poses a problem that assembly is not easy.

An embodiment of the present invention facilitates assembly of an illumination apparatus.

Some embodiments of the present invention will be described below with reference to the accompanying drawings. However, the scope of the present invention is not limited to the following embodiments. An illumination apparatus according to one embodiment of the present invention can be used in a line sensor assembly. First, a line sensor assembly according to one embodiment of the present invention that includes the illumination apparatus according to one embodiment of the present invention, a lens array, a line sensor, and a housing will be explained briefly.

FIG. 5is a perspective view schematically showing the overall structure of a line sensor assembly6according to an embodiment. For the sake of easy understanding of the structure,FIG. 5shows X, Y, and Z directions orthogonal to each other. The line sensor assembly6has an elongated structure extended in the X direction. In this specification, the X direction will sometimes be referred to as an elongation direction hereinafter. The Z direction corresponds to the height direction of the line sensor assembly6. The line sensor assembly6can read a reading target image located in the +Z direction with respect to the line sensor assembly6. The Y direction corresponds to the width direction of the line sensor assembly6. Although the reading target is not particularly limited, an example is a printing medium on which a character or an image is formed on a plane, such as an original or a magazine.

As shown inFIG. 5, the line sensor assembly6includes an illumination apparatus1, a lens array2, a line sensor3, and a housing4. The illumination apparatus1has a shape extending in the X direction, and can irradiate an irradiation region extending in the X direction on the reading target with light at once. The illumination apparatus1emits, from each position of the illumination apparatus1in the X direction toward the reading target via a light guide, light from a light source5located in each end portion. In one embodiment, the light includes a visible light wavelength. Instead of visible light, the light may include X-rays, ultraviolet rays, or infrared rays. In another embodiment, the light may include one, two or more, or all of X-rays, ultraviolet rays, and infrared rays.

The lens array2condenses light emitted from the illumination apparatus1toward the reading target, and guides, to the line sensor3, the light including information of the reading target. The lens array2has a shape extending in the X direction, and can condense light from the irradiation region extending in the X direction on the reading target at once. The lens array2is, for example, a rod lens array having a structure in which rod lenses each extending in the Z direction are arrayed in the X direction. In the example shown inFIG. 5, the lens array2is separated from the illumination apparatus1in the Y direction, and fixed onto the housing4.

The line sensor3detects the light condensed by the lens array2. The line sensor3has a shape extending in the X direction, and can read, at once, the light condensed by the lens array2. As the line sensor3, for example, a known photoelectric conversion element such as a CMOS image sensor can be used. In the example shown inFIG. 5, the line sensor3is separated from the lens array2in the −Z direction, and fixed onto the housing4.

The housing4can support and contain the illumination apparatus1, the lens array2, and the line sensor3. The arrangement of the housing4is not particularly limited. As shown inFIG. 5, the housing4can have a shape extending in the X direction. In one embodiment, the housing4has a black surface or is made of a black material in order to prevent generation of noise caused when light reflected irregularly by the surface reaches the line sensor3.

The arrangement of the line sensor assembly6is not limited to that shown inFIG. 5. For example, the line sensor assembly6may include a first housing in which the illumination apparatus1is provided and a second housing in which the lens array2and the line sensor3are provided. In this case, the first and second housings may be arranged to sandwich the reading target. In this arrangement, the line sensor3can detect light that is emitted from the illumination apparatus1, passes through the reading target, and is condensed by the lens array2.

The line sensor assembly6can be used in a reading apparatus7. The reading apparatus7according to one embodiment of the present invention includes the line sensor assembly6and an output unit that outputs read data obtained by the line sensor assembly6. This output unit is, for example, a substrate fixed to the housing4. This substrate can receive, as read data, a signal from the line sensor3in accordance with a light detection result, perform signal processing if necessary, and then externally output the signal. This substrate can supply externally received power to the illumination apparatus1or the line sensor3.

The illumination apparatus according to the present invention will be described in detail below. Note that in the following description, for the sake of easy understanding of the structure,FIGS. 1 to 4Beach show the X, Y, and Z directions orthogonal to each other. The X direction in each ofFIGS. 1 to 4Bcorresponds to the longitudinal direction of a light guide10, and coincides with the X direction inFIG. 5. On the other hand, the Y and Z directions in each ofFIGS. 1 to 4Bdo not necessarily coincide with those inFIG. 5.FIG. 1is an exploded perspective view showing the arrangement of the illumination apparatus according to one embodiment. The illumination apparatus1according to one embodiment of the present invention includes the light guide10and a light guide cover11. The illumination apparatus1has a structure in which the light guide10and the light guide cover11are assembled, as shown inFIGS. 3A and 4A.

As shown inFIG. 1, the light guide10is a rod-shaped light guide. The light guide10has end faces in the longitudinal direction, which light from the light sources5enters. In this embodiment, the light sources5include two light sources5aand5b, and the light guide10includes end faces100aand100bin the longitudinal direction, which light beams from the light sources5aand5benter, respectively. Furthermore, the light guide10includes, as a first surface101, a light emitting surface that extends in the longitudinal direction and externally emits the light taken from the light source. The light guide10also includes a second surface102that extends in the longitudinal direction and is different from the first surface101. The first surface101and the second surface102will sometimes be referred to as the emitting surface101and the reflecting surface102, respectively, hereinafter. Note that the rod shape indicates a shape extending in the longitudinal direction. The light guide10shown inFIG. 1extends straight. However, part of the light guide10, more specifically, one end of the light guide10may be bent.

The light guide cover11has a shape extending in the longitudinal direction. The light guide cover11is extended to cover the reflecting surface102of the light guide10in the longitudinal direction. Note that the light guide cover11need not cover the light guide10in the entire longitudinal direction of the light guide10. In one embodiment, the light guide cover11covers the central portion of the light guide10in the longitudinal direction. For example, at least one end portion of the light guide10may be bent. As a practical example, the light guide10may include a central portion extending straight and an end portion extending in a direction different from the axial direction of the central portion. In this case as well, the light guide cover11can be provided to cover the central portion of the light guide10. On the other hand, the light guide cover11may be provided to cover, in the entire length direction, the light guide10having at least one bent end portion. The light guide cover11can be applied even if the traveling direction of the light from the light source5to the end portion of the light guide10is different from that of the light from the end portion of the light guide10to the inside of the light guide.

Light can pass through the inside of the light guide10. That is, the light beams from the light sources5aand5benter the light guide10via the end faces100aand100b, respectively. The light is guided in the longitudinal direction while being reflected totally in the light guide10. The light that has reached the reflecting surface102is reflected totally or diffusely. The light guide cover11is configured to cause the light to be reflected diffusely by the second surface102so that the diffusely reflected light emits from the first surface101. That is, the light guide cover11is white as in this embodiment and thus has a function of causing the light that has reached the reflecting surface102to be reflected diffusely, and the reading target is irradiated with some of the diffusely reflected light via the light guide10and the emitting surface101. The emitting surface101may have a convex shape so that the emitted light is concentrated in a linear irradiation region on the reading target. Note that a diffusely reflecting portion such as a rough surface portion or white-coated portion that reflects the reached light diffusely may be provided in at least part of the reflecting surface102. In this case as well, the light guide cover11can return, to the light guide10, the light that has emitted outside the light guide10by diffuse reflection. In the example shown inFIG. 1, it can be said that the light guide cover11can shield the light that has reached at least part of the reflecting surface102. In the example shown inFIG. 1, it can be said that the light guide cover11covers at least part of the reflecting surface102so as to be invisible from the outside.

Light can pass through the inside of the light guide10. For example, the light guide10is a transparent member made of a transparent material such as polyacryl. The light guide cover11is opaque. In one embodiment, the light guide cover11is white to increase the amount of light traveling toward the emitting surface101. An example of the material of the light guide cover11is a polycarbonate containing titanium oxide. On the other hand, to prevent generation of noise caused when light reflected irregularly by the surface reaches the line sensor3, the light guide cover11may be black.

The illumination apparatus1can include one or more light sources5. The light source5may be a component outside the illumination apparatus1. In the example shown inFIG. 1, the illumination apparatus1includes the two light sources5aand5bas the light sources5, and the light guide10includes, at two ends, the end faces100aand100bwhich light beams from the light sources5aand5benter, respectively. However, only one light source5may be used. That is, the illumination apparatus may include one light source5, and the light guide10may include, at one end, an end face100which light from the light source5enters.

The light guide cover11includes an elongated portion extending in the longitudinal direction and at least one finger that holds the light guide10. In one embodiment, the light guide cover11has a long shape with flexibility such as a white polycarbonate member. The finger of the light guide cover11is a portion of the light guide cover11that protrudes from the elongated portion of the light guide cover11.

At least one finger of the light guide cover11can hold the light guide10by applying a force. For example, at least one finger of the light guide cover11can be a flexible piece, and can pinch the light guide10by an elastic force of the flexible piece. On the other hand at least one finger of the light guide cover11may hold the light guide10without applying a force. For example, at least one finger of the light guide cover11may have a protruded portion111as stated below, and the light guide cover11may support the light guide without depending on the elastic force. When the finger pinches or catches the light guide10or catches the light guide10between the finger and the elongated portion, the finger can hold the light guide10even if an external force with a certain strength is applied. On the other hand, by applying a stronger external force, it is possible to attach or separate the light guide10to or from the light guide cover11.

At least one finger of the light guide cover11may include two fingers whose respective distal ends are separated from each other. In this case, at least one finger of the two fingers can be the flexible piece and can pinch the light guide10by an elastic force of the flexible piece. In this embodiment, for example, employing a shape like two fingers separated from each other enables to pinch or catch the light guide10. At least one of these at least two fingers can also be the flexible piece, thus the fingers can pinch the end portion of the light guide10by the elastic force.

The holding portion110including at least one finger of the light guide cover11as a component will be described in detail below. The holding portion110can hold the light guide10even when a certain external force is applied, but when a stronger external force is applied, the light guide10come off the light guide cover11. The light guide cover11includes an elongated portion extending in the longitudinal direction and a holding portion110that holds the light guide10. The holding portion110holds the light guide10at a held position104as one position of the light guide10in the longitudinal direction. On the other hand, the periphery of the light guide10, that is, a portion in a circumferential direction centered on the X-axis is not covered with the light guide cover11.

In this embodiment, at least one finger of the light guide cover11holds the end portion of the light guide10in the longitudinal direction. That is, the holding portion110holds the end portion of the light guide10. The end portion of the light guide10indicates a portion with a length from the end face100of the light guide10, that is, within 10% of the length of the light guide10in the elongation direction. In this embodiment, the light guide cover11may have two or more fingers that hold the light guide10at different positions each other. The light guide cover11as shown inFIG. 3Aincludes two or more holding portions110aand110bthat respectively hold the light guide10at different held positions104aand104b.

In this embodiment, at least one finger also covers the first surface101in the end portion in the longitudinal direction of the light guide10.FIG. 3Ais a sectional view of a plane perpendicular to the elongation direction of the light guide10and the light guide cover11at the held position104according to one embodiment. As shown inFIG. 3A, it is apparent that part of periphery of the light guide10is exposed at the held position104. That is, the light guide10is not completely surrounded by the light guide cover11at the held position104. In the cross section perpendicular to the elongation direction at the held position104, the light guide cover11includes an opening. On the other hand, the holding portions110a,110bcover the first surface101at the held position104.

Therefore, the light guide10can be inserted, from a direction intersecting the longitudinal direction, into a position where it is held by the holding portion110. For example, as shown inFIG. 4A, when assembling the light guide10and the light guide cover11, the light guide10can be inserted from the direction intersecting the longitudinal direction, as indicated by an arrow. That is, since the light guide cover11and the holding portion110have flexibility, the holding portion110is distorted to allow insertion of the light guide10. In addition, with the elastic force of the holding portion110, like the force of a leaf spring, the holding portion110can hold, after insertion, the light guide10not to be removed. This can facilitate assembly or shorten the assembly time. Furthermore, at the time of assembly, the first surface101and the second surface102of the light guide10contact the holding portion110only at the held position104. Therefore, it is possible to reduce distortion of the light guide10caused by a physical impact at the time of assembly.

On the other hand, as shown inFIG. 3B, a state in which the holding portion of the light guide cover11covers the side surface of the light guide10over one round at the held position is illustrated for reference. Therefore, when assembling the light guide10and the light guide cover11, it is necessary to insert the light guide10into the light guide cover11in the longitudinal direction, as indicated by an arrow inFIG. 4B. This embodiment is superior to the example shown inFIG. 3B, as described above.

FIG. 3Ais a sectional view in a direction perpendicular to the longitudinal direction at the held position104according to one embodiment. InFIG. 3A, the light guide cover11long in the X direction includes two fingers110aaand110abas protruded portions each of which protrudes, at the end in the elongation direction, from the elongated portion as a main body long in the elongation direction. The two fingers110aaand110abserve as the holding portion110ainFIG. 3A. In this embodiment, the light guide10is exposed between the fingers110aaand110ab. The exposed portion is not particularly limited, and can be designed in consideration of easy of insertion of the light guide10into the light guide cover11or difficulty of a drop after insertion. That is, the exposed portion may or may not be a portion corresponding to the emitting surface101of the light guide10. Referring toFIG. 1, the two holding portions110aand110bare located at the two ends of the light guide cover11in the X direction. The holding portion110bmay have the arrangement shown inFIG. 3A. At least one of the pair of fingers110aaand110abmay include a drop prevention portion for further suppressing separation between the light guide10and the light guide cover11. Referring toFIG. 3A, a drop prevention portion is provided at the distal end of the finger110aaamong the two fingers110aaand110ab. The drop prevention portion is, for example, a protruded portion111that protrudes from the finger110aato suppress a drop of the light guide10. The protruded portion111may have, for example, a knob shape, a claw shape, or a needle shape with a fold. Since the finger110aaincludes the protruded portion111, the holding portion110can hold the light guide10in a state in which the light guide10is more difficult to be removed. In addition, since the finger110aaincludes the protruded portion111, the holding portion110can hold the light guide10in a state in which the light guide10is more difficult to be removed even when fingers110aa,110abdo not apply the force to light guide10. Note that both the fingers110aaand110abmay have protruded portions. In addition, even when the light guide cover11has one finger, the holding portion110can hold the light guide10in a state in which the light guide10is more difficult to be removed by providing the one finger with the protruded portion111.

In one embodiment, the holding portion110has flexibility. An example of the holding portion110is a resin material like polycarbonate. Note that the material of the holding portion110may be the same as that of the light guide cover11, and the light guide cover11and the holding portion110can be formed integrally. In the embodiment, the distance between the pair of fingers110aaand110abof the holding portion110is shorter than the width of the light guide10. The width of the light guide10indicates the maximum diameter of the light guide10(the longest one of distances between arbitrary two points on the periphery in the cross section perpendicular to the elongation direction at the held position104).

For example, in the example shown inFIG. 3A, the distance between the pair of fingers110aaand110abwhen no external force is applied is represented by L0, the width of the light guide10is represented by L2, and L0<L2 is satisfied. When inserting the light guide10into the light guide cover11, as shown inFIG. 4A, the distance between the pair of fingers110aaand110abcan be increased to L2 or more. On the other hand, after assembling the light guide10and the light guide cover11, the distance between the pair of fingers110aaand110abis represented by L1, and L1<L2 is satisfied. As described above, the distance L1 between the pair of fingers110aaand110abis shorter than the width L2 of the light guide10, and it is thus possible to suppress a drop of the light guide10from the light guide cover11.

In one embodiment, at the held position104, the holding portion110has a shape complementary to the periphery of the light guide10. In one embodiment, the holding portion110covers the first surface101in addition to the second surface102. With these arrangements, the holding portion110can hold the light guide more reliably.

In one embodiment, as shown inFIG. 1, the light guide10includes the end faces100in the longitudinal direction, which light beams from the light sources5enter, and the side portion with the region (emitting surface101) that externally emits light and the region (reflecting surface102) that reflects light. The light guide cover11is configured to cover the side portion of the light guide10in the circumferential direction and not to cover a portion in the circumferential direction. For example, the light guide cover11can cover at least part of the side portion without covering the region that externally emits light. The circumferential direction indicates a circumferential direction on the cross section in the YZ plane of the light guide10. For example, the circumferential direction represents a direction in which the light guide10is surrounded along the edge of the light guide10. That is, the light guide10need not have a cylindrical shape and the circumferential direction need not be a radial direction. The cross section of the light guide10may have an arbitrary shape such as an elliptic shape or a polygonal shape. The light guide cover11includes the drop prevention portion like the holding portion110. This drop prevention portion can hold the light guide10at a drop prevention position (for example, the held position104) so that at least part of the side portion of the light guide10at the drop prevention position is exposed.

As shown inFIGS. 1 and 2, in one embodiment, the light guide10includes a projection103on the second surface102. The projection103is engaged with, for example, the housing4that contains a sensor substrate, a rod lens array, or the like. The engaged portion of the housing4may be a concave portion that receives the projection103. When the projection103is engaged with the housing4, relative movement of the light guide10in the longitudinal direction with respect to the housing4is regulated, and it is thus possible to prevent a positional shift of the light guide10in the longitudinal direction. The light guide cover11includes an opening portion113through which the projection103extends. For example, the opening portion113is a through hole through which the projection103can extend. The projection103and the opening portion113can be formed at positions where, when assembling the light guide10and the light guide cover11in a correct relative arrangement, the projection103extends through the opening portion113to protrude to the outer surface of the light guide cover11. In one embodiment, the light guide10includes one or more projections103. In one embodiment, the projection103is formed in the end portion of the light guide10. With this arrangement, it is easy to assemble the light guide10and the housing4in a correct relative arrangement.

In another embodiment (not shown), the projection103may be engaged with the opening portion113. In this case, the projection103can be engaged with both the housing4and the opening portion113. When the light guide10, the light guide cover11, and the housing4are assembled in a correct relative arrangement, the projection103is engaged with the opening portion113in a state in which it extends through the opening portion113, and also engaged with the engaged portion of the housing4. In this arrangement, relative movement of the light guide10in the longitudinal direction with respect to the light guide cover11and the housing4is regulated, and it is thus possible to prevent a positional shift of the light guide10in the longitudinal direction.

The above-described reading apparatus7can be used as a component of a printing apparatus.FIG. 6is a view showing the schematic arrangement of a printing apparatus8according to one embodiment of the present invention. The printing apparatus8includes the reading apparatus7that reads a medium, a printing unit9athat executes printing on the medium based on the reading result of the reading apparatus7, and conveyance units9bthat convey the medium.

The printing unit9acan print a character, an image, or the like on a medium P (for example, a paper) by an arbitrary method such as an inkjet method or an electrophotographic method. As the conveyance units9b, conveyance rollers that convey the medium from the upstream side to the downstream side can be used. In one embodiment, the printing apparatus8can perform copy processing. In this case, the printing unit9aprints, on the medium, the image read by the reading apparatus7. In one embodiment, the printing apparatus8can perform feedback control. For example, the reading apparatus7can read the medium after printing is executed by the printing unit9a, and transmit the read data to the printing unit9a. Based on the read data, the printing unit9acan confirm the printing state on the medium, and control printing parameters at the time of next printing.

This application claims the benefit of Japanese Patent Applications No. 2017-172405, filed Sep. 7, 2017, and No. 2018-162074, filed Aug. 30, 2018, which are hereby incorporated by reference herein in their entirety.