JP5644224B2 - Document illumination device, document reading device, and image forming apparatus - Google Patents

Description

  The present invention relates to a document illumination device that illuminates a document in a document reading device used in a digital copying machine, an image scanner, and the like, a document reading device including the document lighting device, and an image forming apparatus including the document reading device. .

  In recent years, development of light emitting diodes (hereinafter referred to as “LEDs”) has been actively conducted. The brightness of the LED element is rapidly increasing, and the cost is decreasing. LEDs generally have advantages such as long life, high efficiency, high G resistance, and monochromatic light emission, and are expected to be applied in many lighting fields. One of the uses is a document illumination device of a document reading device such as a digital copying machine or an image scanner.

The emission spectrum of the white light emitting LED element covers the visible wavelength band, and can be used for a document illumination device of a document reading device capable of reading a color image. For this reason, a wide variety of document illumination devices using white LEDs have been proposed.
Further, when the LED is used as a light source, the higher the illumination efficiency, the higher the energy saving effect. Therefore, it is important from the environmental viewpoint to provide a reading illumination system (original illumination device) having a high illumination efficiency using the LED light source.

  A reading illumination system using an LED as a light source includes a method using a light guide plate (see, for example, Patent Document 1). According to such a method using a light guide plate, while light from LED light sources arranged in a line is transmitted while being totally reflected in the light guide plate, the light diffuses and illuminance distribution unevenness is reduced. It has been known.

  In many cases, a pseudo white LED is used as the LED, but the size of the blue light emitting chip of the pseudo white LED is considerably smaller than the size of the phosphor that converts the wavelength to yellow light, and the light emission position is also different. The chromaticity of the illumination light was likely to vary on the reading surface. On the other hand, if both the blue light and the yellow light by the phosphor are diffused and mixed only by the diffusing means such as the diffusing sheet in order to eliminate the chromaticity variation, the efficiency of illuminating the original reading surface decreases. There is a problem.

  Since the material of the conventional light guide used as the light guide plate in the reading illumination system as described in Patent Document 1 is hard, the degree of freedom in bending is extremely low, and the degree of freedom in arrangement of the illumination optical system is limited. Therefore, there is a limit to downsizing and thinning of the apparatus. On the other hand, when the propagation distance of the light guide is shortened in order to reduce the size of the lighting device, there is a problem that the light diffusion effect in the light guide is reduced and the effect of improving the chromaticity variation is reduced.

  Therefore, an object of the present invention is to provide a document illuminating device having a high degree of freedom in arranging the light guides, enabling downsizing of the device, and being excellent in reducing variations in illumination chromaticity and color unevenness of the document reading surface, And a document reading device including the document illumination device, and an image forming apparatus.

In order to solve the above-described problems, a document illumination device, a document reading device, and an image forming apparatus according to the present invention are as follows.
[1] A document illuminating device for irradiating a reading target area on a document surface in a document reading device,
A plurality of light emitting diodes arranged along the main scanning direction of the irradiation region irradiated with light;
A light guide that guides light emitted from the plurality of light emitting diodes to the irradiation region;
A holding member for holding the light guide,
The light incident surface of the light guide from the light emitting diode is disposed in contact with the light emitting surface of the light emitting diode, and is perpendicular to the sub-scanning direction of the irradiation region irradiated with the light,
The lightguide have a flexibility, a document illumination apparatus characterized by comprising the following sheet-shaped member thickness 1.0 mm.
[2] The document according to [1], wherein a thickness direction of the light guide is perpendicular to a propagation direction of light emitted from the plurality of light emitting diodes in the light guide. It is a lighting device.
[ 3 ] The above [1] or [2] , wherein the light guide includes a surface protective layer on at least one surface of the surface excluding the light incident surface and the light output surface from the light emitting diode. This is a document illumination device.
[ 4 ] The above [1] to [3] , wherein the light guide is arranged so that at least a part from the light incident surface to the light emission surface from the light emitting diode is curved . The document illumination device according to any one of the above.
[ 5 ] A light diffusing unit is provided between the light emitting surface of the light guide from the light emitting diode and the document surface, and the light emitted from the light emitting surface is read through the light diffusing unit. The document illumination device according to any one of [1] to [ 4 ], wherein the target region is irradiated.
[6] The original illumination according to any one of [ 3 ] to [5], wherein the light guide is made of a member including a core layer and a clad layer, and the surface protective layer is the clad layer. Device.
[7] The above-mentioned [ 3 ] to [5], wherein the surface protective layer is a sheet member having a refractive index lower than that of a light guide member of the light guide. This is a document illumination device.
[8] The document illuminating device according to any one of [ 3 ] to [5], wherein the surface protective layer is a metal reflection sheet member.
[9] The document illumination device according to any one of [1] to [8], wherein the light-emitting diode is a side-view type LED.
[10] The document illuminating device according to any one of [ 5 ] to [9], wherein the light guide and the light diffusing means are bonded to each other with a light-transmitting member. .
[11] An original reading apparatus comprising the original illumination device according to any one of [1] to [10].
[12] An image forming apparatus comprising the document reading device according to [11].

As an effect of the present invention, according to the first aspect of the present invention, there is provided an original illuminating device for irradiating a reading target area on an original surface in an original reading apparatus, wherein the irradiation area irradiated with light is arranged along the main scanning direction. A plurality of light emitting elements, a light guide that guides light emitted from the plurality of light emitting elements to the irradiation region, and a holding member that holds the light guide, and the light guide is flexible. Since the document illumination device is composed of a sheet-like member having a high degree of freedom in arranging the light guide, the device can be reduced in thickness and size, and the effect of reducing variations in illumination chromaticity and color unevenness can be achieved. Excellent.
According to a second aspect of the present invention, in the document illuminating device according to the first aspect, the light guide has a surface protective layer on at least one surface of the surface excluding the light incident surface and the light emitting surface from the light emitting element. Therefore, damage to the surface of the light guide and leakage of light can be prevented and light utilization efficiency can be increased.
According to a third aspect of the present invention, in the document illumination device according to the first or second aspect, at least a part of the light guide from the light incident surface to the light output surface is curved. Therefore, the apparatus can be reduced in size and thickness, and the illumination efficiency can be improved.
According to a fourth aspect of the present invention, in the original illuminating device according to the first to third aspects, the light diffusing means is provided between the light emitting surface of the light guide from the light emitting element and the original surface. And since the light radiate | emitted from the said output surface is irradiated to the said reading object area | region via this light-diffusion means, illumination uniformity can be improved further and the safety | security with respect to a user can be ensured.
According to a fifth aspect of the present invention, in the document illuminating device according to any one of the first to fourth aspects, the light incident surface from the light emitting element of the light guide is in contact with the light emitting surface of the light emitting element. Therefore, the optical coupling efficiency to the light guide can be increased, and since the light guide has flexibility, damage to the light emitter due to impact can be reduced.
According to a sixth aspect of the present invention, in the document illuminating device according to any one of the second to fifth aspects, the light guide includes a member including a core layer and a clad layer, and the surface protection layer is the clad layer. Therefore, it is possible to protect the core layer and prevent light leakage to increase light utilization efficiency, reduce light loss when bent, and stabilize light guiding performance.
According to a seventh aspect of the present invention, in the document illuminating device according to any one of the second to fifth aspects, the surface protective layer has a lower refractive index than the light guide member of the light from the light emitting element. Since it is a member, it is possible to protect the core layer and prevent light leakage to increase light utilization efficiency, reduce light loss when bent, and stabilize light guiding performance.
According to the invention of claim 8, in the document illuminating device according to any one of claims 2 to 5, since the surface protective layer is a metal reflection sheet member, the core layer is protected and light leaks. The light utilization efficiency can be improved, the light loss when bent can be reduced, and the light guide performance can be stabilized.
According to the invention of claim 9, in the document illumination device according to any one of claims 1 to 8, since the light emitting element is a side view type LED, it is easy to optically couple to a thin light guide, Can be further reduced in thickness and size.
According to the invention of claim 10, in the document illuminating device according to any one of claims 4 to 9, since the light guide and the light diffusing means are bonded by a light-transmitting member, The positional deviation of the light diffusing means can be prevented, and the stability of the light diffusing characteristics can be improved.
According to the eleventh aspect of the invention, since the original reading apparatus includes the original illuminating device according to any one of the first to tenth aspects, the illumination efficiency is high and the effect of reducing variations in illumination chromaticity on the original reading surface is excellent. A miniaturized document reading apparatus with high dynamic stability of reading performance is provided.
According to the twelfth aspect of the present invention, since the image forming apparatus includes the original reading device according to the eleventh aspect, the illumination efficiency at the time of original reading is high, and the effect of reducing variation in illumination chromaticity on the original reading surface is excellent. A miniaturized image forming apparatus is provided.

It is a schematic diagram which shows an example of the several light emitting element arrange | positioned on a board | substrate. It is the schematic which shows the structure which illuminates a document stand from a document illumination device. It is a schematic diagram which shows the example which has arrange | positioned the side view type LED chip as a light emitting element. It is the schematic diagram which showed the example which a light guide consists of a member provided with a core layer and a clad layer. It is a schematic diagram which shows the example which inserted the sheet | seat member of refractive index lower than the member of a light guide part, a metal reflection sheet member, etc. as a surface protective layer between the board | substrate and the light guide sheet. It is a schematic diagram which shows the other example of the aspect which curved the light guide in the irradiation direction of light. It is a schematic diagram which shows the aspect which provided the board | substrate above the Y direction of the light guide with respect to FIG. It is a schematic diagram which shows the aspect which inclined the output surface of the light guide to the taper shape with respect to FIG. FIG. 8 is a schematic diagram showing an aspect in which the exit surface of the light guide is inclined in a tapered shape with respect to FIG. 7. FIG. 10 is a schematic diagram showing a mode in which a pair of document illumination devices are arranged substantially symmetrically in the sub-scan section at the center of the reading area with respect to FIG. 9. It is a schematic diagram which shows the aspect which added the board | substrate so that a light guide may be clamped with respect to the original document illuminating device of FIG. It is a schematic diagram which shows the aspect which inclined and arrange | positioned the light guide to about 20 degree | times with respect to the Y-axis. It is a schematic diagram which shows the aspect by which the incident surface side edge part of the light guide was tapered. It is a schematic diagram of sectional drawing of the output surface of a light guide. It is a schematic diagram which shows an example of the aspect which fixes a light guide sheet with a holding member. It is a schematic diagram which shows the aspect whose light guide is thinner than the length of the Y direction of a light emitting element. It is a schematic diagram which shows the aspect which isolate | separates the output surface of a light guide into two layers. It is a schematic diagram of the LED array which has arrange | positioned the light emitting element on the upper and lower surfaces of a board | substrate. It is a schematic diagram which shows the aspect which provided the light emitting element and the light guide on the upper and lower surfaces of the board | substrate. 1 is a schematic diagram showing an embodiment of a document reading apparatus of the present invention. It is a schematic diagram which shows the other embodiment of the original document reading apparatus of this invention. 1 is a schematic diagram showing an embodiment of an image forming apparatus of the present invention.

  Hereinafter, a document illumination device, a document reading device, and an image forming apparatus according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments of the examples shown below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art. Any aspect is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited.

<Original illumination device>
The document illumination device of the present invention includes a plurality of light emitting elements arranged along a main scanning direction of an irradiation area irradiated with light, a light guide that guides light emitted from the plurality of light emitting elements to the irradiation area, A holding member for holding the light guide. The light guide is made of a flexible sheet-like member and can be easily bent.

FIG. 1 shows an LED array composed of a plurality of light emitting elements.
As shown in FIG. 1, a plurality of light emitting elements (LED chips) 1 are spaced apart from each other on a mounting substrate (hereinafter simply referred to as “substrate”) 2. The X direction in the figure is the main scanning direction. As shown in FIG. 1, the effect of improving the illuminance uniformity on the image sensor can be obtained by making the pitch P1 in the peripheral part narrower than the interval (pitch) P2 between the LED chips in the central part in the X direction.

FIG. 2 shows an arrangement of a document illumination device and a document table according to the present invention as a schematic diagram of a main part of the document reading device. In the document reading apparatus, the document scanning direction (sub-scanning direction) is Z, the document main scanning direction is X, and the direction perpendicular to X and Z is the Y direction.
FIG. 2 shows a mode in which a document illumination device is provided facing the document table 3 on the left and right in the sub-scanning direction (Z direction).
The LED chip 1 disposed on the substrate 2 is disposed close to the incident surface of a light guide (hereinafter referred to as “light guide sheet”) 4 made of a sheet-like member, and the light incident on the incident surface is guided. The document reading area of the document table 3 is illuminated from the exit surface of the light 4 sheet.

  The arrows in FIG. 2 indicate the main direction of light emitted from the exit surface of the light guide sheet 4. The light emitted from the light guide sheet 4 has a diffusion spread. When the position where the left and right principal rays intersect with each other indicated by the dotted line is slightly above (+ Y side) the document surface 3, the illuminance flatness in the sub-scanning direction becomes wide. Further, the deterioration of the illumination depth characteristic (illuminance flatness) when the document is lifted is reduced.

The LED chip 1 can be configured to be thin in the Y direction of the lighting device by selecting the side view type. FIG. 3 shows a configuration example of the LED array in which the side-view type LED chips 1 are spaced apart in the main scanning direction.
Since the side view type has a lower height in the Y direction of the LED chip 1 and a smaller light emitting surface than the top view type, it can be easily optically coupled to the thin light guide sheet 4 and the entire device can be made thinner. When the propagation direction length of the light guide sheet 4 is the same, the thinner sheet is the boundary surface between the sheet surface and the surface protective layer (for example, the boundary surface in the case of having a core layer and a cladding layer described later). Increases the number of reflections at. For this reason, the diffusion effect of the light emitted from the LED chip 1 is increased, and when the light emitting chip 1 is a pseudo white LED, the mixing effect of blue light and yellow light is increased, and chromaticity unevenness on the document reading surface is increased. Less. Since the light guide sheet 4 has already been mixed, the chromaticity unevenness is low not only on the document surface but also at the position where the document is lifted. Thus, since both the LED chip 1 and the light guide sheet 4 are thin, the lighting device can be thinned.
3 shows an example of an arrangement in which the pitch of the LED chip 1 is changed as in FIG. 1, but with this arrangement, a flat illuminance distribution can be obtained and the light utilization efficiency is high. Become.

The light guide sheet 4 is long in the X direction, the length in the X direction is substantially equal to the length in the X direction of the reading target region, and the Z direction is shorter than the X direction. The Y direction is the thickness of the light guide sheet.
The conventional light guide plate is a member thicker than the size of the LED chip and has a thickness of at least 1.5 mm or more (for example, about 5 mm). The light guide sheet 4 provided in the lighting device of the present invention is shown in FIG. As shown, a member thinner than the size of the LED chip 1 in the Y direction may be used. Specifically, a member having a thickness of 1.0 mm or less (for example, 0.5 mm) can be used.

  Further, since the light guide sheet 4 is thinner than a conventional light guide plate and is highly flexible and can be easily bent, the use of the light guide sheet 4 allows the document of the present invention. The illumination device is thinner than the conventional device. (The details will be described later with reference to FIG. 6).

  Furthermore, by using the light guide sheet 4 thinner than 1.0 mm, the number of total internal reflections of light propagating in the light guide can be increased due to the thin sheet. As a result, on the exit surface of the light guide sheet 4, the effect of mixing the light from the LED chip 1 is enhanced, and the chromaticity variation is also improved.

  For example, assuming that the document reading width in the evaluation area is 3 mm, the result of an actual measurement comparison using ΔCx + ΔCy as an index value from the difference ΔCx in the chromaticity Cx and the difference ΔCy in the chromaticity Cy in the evaluation area is 0.5 mm thick The body sheet can reduce the color unevenness in the document reading area to ½ or less of a conventional light guide plate having a thickness of 1.6 mm.

  Examples of the flexible sheet member that constitutes the light guide sheet 4 include sheet members such as acrylic resin, silicon resin, and polycarbonate resin.

The light guide sheet 4 may have a surface protective layer on at least one surface excluding the light incident surface and the light output surface from the LED chip 1, and the light guide sheet 4 has a core layer and a clad layer. In the case of comprising, the surface protective layer may be a clad layer.
FIG. 4 shows an example of a document illumination device including a light guide sheet 4 including a core layer 4A and a clad layer 4B. Since the core layer 4A is protected by the clad layer 4B which is a surface protective layer, the occurrence of light loss due to scratches on the surface of the light guide sheet 4 is reduced, and handling becomes easy. Further, by optimizing the cladding layer 4B by design, it is possible to reduce the light loss when the light guide sheet 4 is bent (bending) and to stabilize the light guide performance.

When the light guide sheet 4 is not a member provided with the cladding layer 4B, as shown in FIG. 5, as the surface protective layer 9, a sheet member having a refractive index lower than that of the light guide member or a metal member is used. A reflective sheet member or the like may be inserted between the substrate 2 and the light guide sheet 4. The surface protective layer protects the light guide surface of the light guide sheet 4 to prevent light leakage, and the light use efficiency can be improved. Moreover, the light loss at the time of curving of the light guide sheet 4 can be reduced, and the light guide performance can be stabilized.
In addition, you may reduce the light absorption to a board | substrate more by making the surface of the board | substrate 2 which contact | connects the light guide sheet 4 into a highly reflective surface.

The light guide sheet 4 may be arranged such that at least a portion of the light propagation direction between the incident surface and the exit surface is curved. The light guide sheet 4 having flexibility can be arranged so as to be curved so that the light emitting surface faces in a desired direction.
FIG. 6 shows an example in which the light guide sheet 4 is curved and arranged.
The apparatus can be reduced in thickness and size by adopting a configuration that is thin in the Y direction and short in the Z direction, rather than the configuration in which the entire light guide sheet 4 is inclinedly arranged in the YZ plane. For example, the thickness of the light guide sheet 4 is about 1 mm, the thickness of the substrate 2 is about 1 mm, and even if a part of the light guide sheet 4 is curved, the total thickness is about 3 mm.

  FIG. 7 shows an example in which the substrate 2 is provided on the upper side in the Y direction of the light guide sheet 4 with respect to the embodiment of FIG. By adopting such a configuration, the Y direction of the apparatus can be reduced by an amount corresponding to the thickness of the substrate 2.

  FIG. 8 shows an example in which the exit surface of the light guide sheet 4 is inclined in a tapered shape with respect to the embodiment of FIG. With such a configuration, it is possible to irradiate the original reading area with the illumination light without curving the light guide sheet 4, so that the apparatus can be thinned in the Y direction.

  Moreover, FIG. 9 has shown the example which inclined the output surface of the light-guide sheet | seat 4 in the taper shape with respect to the aspect of FIG. By adopting such a configuration, it is possible to irradiate the original reading area with the illumination light without curving the light guide sheet 4, so that the Y direction of the apparatus can be made thinner than the mode of FIG. 7. Can do.

  FIG. 10 shows an example in which the document illumination device is arranged substantially symmetrically in the sub-scanning section with respect to the center of the document reading area with respect to the mode of FIG. It can cope with higher illuminance than FIG. The arrangement of each document illumination device need not be completely symmetric. Adjustments can be made as appropriate by changing the modulation pitch of the array of LED chips 1 or changing the number of LED chips 1. Further, by adopting the configuration as shown in FIG. 10, even if there is a step on the document surface, it is difficult to be hidden.

  FIG. 11 shows an example in which a member 6 is added to the document illumination device shown in FIG. By configuring so that the light guide sheet 4 is sandwiched between the substrate 2 and the member 6, the position of the light guide sheet 4 is stabilized. Further, in order to reduce attenuation due to light absorption at the boundary between the substrate 2 and the member 6 and the light guide sheet 4, a sheet having a refractive index lower than that of the light guide part of the light guide sheet 4 is sandwiched between the cladding layer and the clad layer. And the reflectance of the surface can be increased.

  FIG. 12 shows an example in which the light guide sheet 4 is arranged to be inclined with respect to the Y axis, and the inclination angle is about 20 degrees. With such a configuration, useless light is not illuminated outside the width of the reading target area in the sub-scanning direction, and the illumination efficiency is increased.

FIG. 13 shows an aspect in which the incident surface side end of the light guide sheet 4 is tapered.
By tapering the incident end side of the light guide sheet 4, the coupling efficiency can be improved and contact between the substrate 2 and the light guide sheet 4 can be avoided. In addition, the light guide sheet 4 may be provided with upper and lower clads as a surface protective layer. Further, as in the mode shown in FIGS. 2 and 4, a document illumination device may be added on the right side to provide a pair of opposed illuminations.

  As shown in FIG. 13, the light coupling efficiency to the light guide sheet 4 can be increased by arranging the incident surface of the light guide sheet 4 so as to contact the light emitting surface of the light emitting element 1. . Since the light guide sheet 4 has flexibility and is soft, even if the light guide sheet 4 is disposed in contact with the light emitting surface of the light emitting element 1, it is possible to suppress the occurrence of damage due to impact or the like.

  A light diffusing unit is provided between the exit surface of the light guide sheet 4 and the document surface placed on the document table 3, and the light emitted from the exit surface is read through the light diffusing unit. It is good also as a structure irradiated to an area | region. Thus, by providing means for adjusting the light diffusion characteristics, it is possible to adjust the characteristics of the illumination in the main scanning direction and the sub-scanning direction, and the illuminance uniformity can be further improved. In addition, when it is assumed that the user has looked into the lighting device, safety can be ensured by selecting an appropriate diffusion characteristic.

  Furthermore, the exit surface of the light guide sheet 4 and the light diffusing means may be bonded to each other with a light transmissive member. Since the relative position between the light guide sheet 4 and the light diffusing means is stabilized by bonding with the light transmissive material, the illuminance of the illumination light reaching the document surface 3 and its main scanning direction and sub-scanning direction The variation of the is improved.

  FIG. 14 is a cross-sectional view of the light exit surface of the light guide sheet 4. The light diffusing means 5 is larger than the light guide sheet 4. In such a case, a portion of the light diffusing means 5 through which light does not pass can be held and fixed by contacting the holding member.

  An example of a mode in which the light guide sheet is fixed by the holding member is shown in FIG. FIG. 15 shows one end in the X direction, and the light guide sheet 4 includes light diffusing means 5. In the example shown in FIG. 15, the light exit surface of the light guide sheet 4 is a through hole, and the light diffusing means 5 is larger than the light guide sheet 4, so that the portion through which light does not pass comes into contact with the holding member 10. Can be held and fixed. When a hole is provided in the light diffusion means 5 and screwed to the holding member 10, the position of the light guide sheet 4 can be adjusted by the diameter of the formed hole. Since the light guide sheet 4 is long in the X direction, a plurality of holding and fixing portions may be provided in the X direction. The holding member 10 is held and fixed to the base surface 8.

  Thus, by holding and fixing the light guide sheet 4 by the holding member 10, the occurrence of positional deviation between the LED chip 1 and the incident surface of the light guide sheet 4 is suppressed, and the optical coupling efficiency of each LED chip 1 is reduced. Stabilization and stabilization against dynamic vibration shock can be obtained. Note that the method of holding the light guide sheet 4 is not limited to the method shown in FIG. 15, and can be appropriately selected as long as the document illumination device can be thinned.

  FIG. 17 shows an aspect in which the wedge-shaped member 11 is provided on the light exit surface side of the light guide sheet 4 and the light guide sheet 4 is separated into two layers. The light emitted from the separated upper layer is illuminated by the main illumination, and the light emitted from the lower layer is illuminated by the opposed illumination member. The wedge-shaped member 11 is continuous in the main scanning direction X direction. The refractive index of the wedge-shaped member 11 is preferably lower than the refractive index of the light guide portion of the light guide sheet 4. Or it is preferable that the wedge-shaped member 11 is a member with a high reflectance of the contact surface with the light guide sheet 4 at least.

  FIG. 18 shows a configuration example in which the LED chip 1 is spaced apart from the lower portion of the substrate in the LED array shown in FIG. Since the LED chip 1 is provided on each of the upper and lower portions of the substrate, it can be applied to a light guide sheet having a two-layer structure.

  In FIG. 19, the LED chip 1 and the light guide sheets (41, 42) are respectively provided above and below the substrate 2, and the light guide sheet 41 at the top of the substrate directly illuminates the original surface, and the light guide at the bottom of the substrate The sheet 42 is configured to illuminate the document surface via the opposed reflection illumination means 9. With such a configuration, the efficiency of direct illumination is improved. Since the light guide sheets 41 and 42 are independent, the direction of the exit surface suitable for each of the main illumination and the counter illumination can be set. In general, the light use efficiency is improved, and the dissipation of the illumination light to the parts that do not need to be read can be reduced. Moreover, the brightness of the light emitters disposed on the lower side of the substrate can be adjusted as appropriate according to the number of LED chips 1 and the injection current in accordance with the illuminance ratio between the counter illumination and the main illumination.

<Document reader>
The document reading apparatus according to the present invention includes at least a reading illumination system including the above-described document illumination apparatus according to the present invention, a reading optical system including a reflection mirror and an imaging lens, and a photographing element. FIG. 20 shows a configuration example of the document reading apparatus.
As shown in FIG. 20, the illumination light reflected by the document surface 22 is received on the image sensor 25 via the reading optical system. An example of the image sensor 25 is a CCD. The optical information of the document surface information imaged on the image sensor 25 can be converted into an electrical signal, and the image information of the document 23 can be read.
The first traveling body 29a holding the document illumination device and the first reflecting mirror 26 is at a scanning speed V, and the second traveling body 29b holding the second and third reflecting mirrors is at a scanning speed V / 2. Scan and read document information. Reading scanning can be performed while the optical path length from the document surface 22 to the image sensor 25, in other words, the conjugate length of the reading optical system is kept constant.

  Since the document illumination device of the present invention is thinned, the document reading device of the present invention can also be configured to be thin and compact. In addition, since the area where the illuminance distribution in the sub-scanning direction is flat is wide, the installation error of the optical elements such as the reflection mirror and the imaging lens and the dynamic fluctuation accompanying the scanning drive are allowed, and the light receiving surface of the image sensor 25 is Thus, it is possible to realize a device having excellent stability of the received light signal in the above, or to relax the tolerance of these optical elements. It is possible to provide an original reading apparatus that is resistant to fluctuations in the received light signal on the imaging surface due to static positional deviation of the reading optical system and dynamic position fluctuations.

FIG. 21 shows another configuration example of the document reading apparatus of the present invention.
In the example shown in FIG. 21, the document reading apparatus holds the document illumination device of the present invention, the imaging lens 24, the reflection mirror 26, and the image sensor 25 with one traveling body 29. Image information of the document 23 on the document table 21 is read by driving the traveling body 29 at a linear velocity V in the sub-scanning direction.
In the apparatus shown in FIG. 21, since it is not necessary to drive the reflection mirror 26 at the time of scanning and reading, the drive mechanism apparatus can be simplified, and the entire apparatus can be reduced in size and weight. Further, even when vibration or the like occurs when the traveling body 29 is driven to scan, the relative positional deviation between the illumination device, the reading optical system (the reflection mirror 26, the imaging lens 24), and the image sensor 25 is further reduced. Therefore, the characteristics of the optical signal received on the light receiving surface of the image sensor 25 are further stabilized. Since the illumination device of the present invention is thin and compact, the document reading device of the present invention is also a compact device.

<Image forming apparatus>
An image forming apparatus of the present invention includes the above-described original reading apparatus of the present invention. The configuration and operation of the image forming apparatus of the present invention will be described below.
FIG. 22 is a schematic front view showing the internal structure of the full-color copying machine 101 according to an embodiment. An image forming unit 103 for forming a color image is provided at the center of the apparatus main body 102 of the copying machine 101. The image forming unit 103 includes four drum-shaped photosensitive members 104 that are spaced apart at equal intervals and arranged in parallel in the horizontal direction, a charging roller 105 that uniformly charges the outer peripheral surface of the photosensitive member 104, and a charging roller 105. An exposure device 106 that forms an electrostatic latent image by exposing the outer peripheral surface of each of the photosensitive members 104 charged in accordance with the image data, and supplying the toner to the electrostatic latent image to convert the electrostatic latent image into a toner image A developing device 107 that visualizes the toner image, an intermediate transfer belt 108 to which the toner image on the photoconductor 104 is sequentially transferred, and a cleaning that removes toner remaining on the photoconductor 4 after the transfer of the toner image onto the intermediate transfer belt 108 The apparatus 109 includes a transfer roller 110 that transfers the toner image transferred onto the intermediate transfer belt 108 to the recording medium S, and the like. Note that toner images of different colors (Y: yellow, M: magenta, C: cyan, K: black) are formed on the four photoconductors 104, and the toner images of these colors are formed on the intermediate transfer belt 108. By being transferred, a color toner image is formed on the intermediate transfer belt 108, and this color toner image is transferred to the recording medium S.

In the upper part of the apparatus main body 102, an ADF 111 for automatically feeding a document, a contact glass 112 on which the document is placed, and a document automatically fed by the ADF 111 or a document placed on the contact glass 112 are read. A document reading device 113 is arranged.
The document reading device 113 includes first and second traveling bodies 114 and 115 capable of traveling at a speed of 2: 1 in parallel with the contact glass 112, a lens 116, a CCD 117 serving as an image reading unit, and the like. The first traveling body 114 is reflected on the document surface by the document illumination device 118 of the present invention for illuminating the document surface of the document placed on the contact glass 112 or the document conveyed by the ADF 11. A first mirror 119 that reflects the reading light traveling along the reading optical axis is mounted. A second mirror 120 and a third mirror 121 that further reflect the light reflected by the first mirror 119 are mounted on the second traveling body 115. A lens 116 and a CCD 117 are disposed in front of the reading light sequentially reflected by the first to third mirrors 119, 120, and 121 in the traveling direction.

  A plurality of, for example, four-stage paper cassettes 124 for storing the recording medium S are provided at the lower part of the apparatus main body 102. The recording media S stored in these paper cassettes 124 are separated and fed one by one by the pick-up roller 125 and the feed roller 126, and the separated and fed recording media S are conveyed by the paper provided in the apparatus main body 102. It is conveyed along the path 127. On the sheet conveyance path 127, a registration roller 128, a transfer roller 110, a fixing device 129, a paper discharge roller 130, and the like are arranged.

  In such a configuration, laser light corresponding to the image data of each color (yellow Y, magenta M, cyan C, black K) is emitted from the semiconductor laser of the exposure device 106 according to the reading result by the document reading device 113, An electrostatic latent image is formed by exposing the outer peripheral surface of each photoconductor 104 to which the laser light is uniformly charged by the charging roller 105. Each color toner is supplied from each developing device 107 to the electrostatic latent image, whereby a toner image of each color is formed. The toner image on each photoconductor 104 is sequentially transferred onto an intermediate transfer belt 108 that moves in synchronization with the photoconductor 104, and a color toner image is formed on the intermediate transfer belt 108.

  On the other hand, when the image forming operation in the image forming unit 103 is started, the recording medium S starts to be separated and fed from the sheet cassette 124 and is separated and fed on the sheet conveyance path 127. Is transferred to a transfer position between the intermediate transfer belt 108 and the transfer roller 110 by a registration roller 128 that is driven to rotate intermittently.

Next, the registration roller 128 is rotationally driven, and the recording medium S is sent between the intermediate transfer belt 108 and the transfer roller 110, whereby the color toner image on the intermediate transfer belt 108 is transferred onto the recording medium S. The color toner image transferred onto the recording medium S is fixed to the recording medium S while the recording medium S passes through the fixing device 129, and the recording medium S on which the color toner image is fixed is discharged by the paper discharge roller 130. The paper is discharged onto the tray 131.
The document reading device 113 can be operated independently as a scanner device.

1 LED chip (light emitting device)
2 Board (LED mounting board)
3 Document table 4 Light guide (light guide sheet)
4A Core layer 4B Clad layer 5 Light diffusion means

JP-A-8-265509

Claims (12)

A document illuminating device for irradiating a reading target area on a document surface in a document reading device,
A plurality of light emitting diodes arranged along the main scanning direction of the irradiation region irradiated with light;
A light guide that guides light emitted from the plurality of light emitting diodes to the irradiation region;
A holding member for holding the light guide,
The light incident surface of the light guide from the light emitting diode is disposed in contact with the light emitting surface of the light emitting diode, and is perpendicular to the sub-scanning direction of the irradiation region irradiated with the light,
Document illumination apparatus, characterized in that the light guide is flexible and have a, consisting of the following sheet member thickness 1.0 mm. 2. The document illumination device according to claim 1, wherein a thickness direction of the light guide is perpendicular to a propagation direction of light emitted from the plurality of light emitting diodes in the light guide. 3. The light guide is, at least on one side, excluding the incident and exit surfaces of the light from the light emitting diode of the surface, document illumination apparatus of claim 1 or 2, characterized in that it comprises a surface protective layer. The light guide is provided with a document according to any one of claims 1 to 3 in which at least a part between the to the exit surface, characterized in that it is arranged to be curved from the plane of incidence of light from the light emitting diode Lighting device. Light diffusing means is provided between the light emitting surface of the light guide from the light emitting diode and the document surface, and the light emitted from the light emitting surface enters the reading target region via the light diffusing means. document illumination apparatus according to claim 1, characterized in that irradiated 4. 6. The document illumination device according to claim 3 , wherein the light guide is made of a member having a core layer and a clad layer, and the surface protective layer is the clad layer. 6. The document illuminating apparatus according to claim 3 , wherein the surface protective layer is a sheet member having a refractive index lower than that of a light guide member of the light guide. 6. The document illuminating device according to claim 3 , wherein the surface protective layer is a metal reflection sheet member. 9. The document illumination device according to claim 1, wherein the light emitting diode is a side view type LED. 10. The document illumination device according to claim 5 , wherein the light guide and the light diffusing unit are bonded to each other by a light transmissive member.   An original reading apparatus comprising the original illumination device according to claim 1. An image forming apparatus comprising the document reading device according to claim 11.

Images