JP2008180842A - Illumination apparatus, image reading apparatus, and image forming apparatus - Google Patents

Abstract

In an illuminating device in which light sources are arranged in a main scanning direction, the illuminance distribution of the illuminating device can be made uniform, and illuminance between different illuminating devices can be prevented from becoming non-uniform. In an illuminating device including an LED array 103 formed by arranging a plurality of LEDs, the LED array 103 is divided into two groups classified into different levels (level A and level B) based on a reference value of luminous intensity. The LEDs are arranged alternately. Further, the LEDs classified into five levels are arranged based on a predetermined rule. Further, different levels of LEDs are driven as drive devices by drive circuits that can be adjusted for each group.
[Selection] Figure 4

Description

  The present invention relates to an illuminating device, an image reading device, and an image forming apparatus, and more particularly, to an illuminating device, an image reading device, and an image forming device provided with a light irradiation body formed by arranging a plurality of light emitting elements.

  As a general reduction optical system image reading apparatus, there is an image reading apparatus that irradiates a document with light and reads reflected light of the document with an image pickup device composed of a CCD element, a CMOS element, or the like. As such an image reading apparatus, there is an illumination apparatus that includes a cylindrical xenon lamp as a light source. In such an image reading apparatus, the irradiation light of the xenon lamp is applied to the document on the contact glass, and the diffuse reflection light of the document is guided to the image sensor through an optical element such as a lens, and the image signal is output by the image sensor. Convert to electrical signal.

  Further, in such an image reading apparatus, a first traveling body including a first mirror that deflects reflected light from the original, a second mirror that further deflects light from the second mirror, and a second mirror including a third mirror. A traveling body is provided, and the first traveling body and the second traveling body travel on a rail provided in the image reading apparatus, thereby scanning a document. In such an image reading apparatus, the first traveling body is provided with a reflecting plate for reflecting the light from the xenon lamp to optimize the illuminance distribution and eliminating the shadow when reading the cut and pasted document.

  In recent years, there has been a demand for shortening the rise time, saving energy, and prolonging the life of the light source in the image reading apparatus, and a light source that employs a light emitting diode (LED) as an alternative light source for the xenon lamp has been put into practical use. . When the LED is used in the reduction optical system, the distance from the document surface to the image pickup device is longer than that in the equal magnification optical system, so that the attenuation of light between them is increased. Therefore, a higher document surface illuminance is required. Therefore, an attempt has been made to increase the illuminance on the document surface by arranging a plurality of LEDs in an array in the main scanning direction.

  In Patent Document 1, a white LED array is used as a light source for irradiating a document, a controller for setting a lighting region of the white LED array according to the document size and application, a lighting region transfer unit, LED ON / OFF, and the light amount. It has a variable light source lighting control unit, etc., and the white LED array groups are arranged in parallel in a plurality of rows, and the interval of each white LED array group is set to a constant multiple of the light receiving element line interval. There is described an image reading apparatus in which the interval is set to a resolution interval required for document reading and the mounting positions of adjacent white LED array groups in the main scanning direction are shifted by half a pixel.

Further, in Patent Document 2, in an image reading apparatus including a light source including a cold cathode tube and an LED array, the LED array has an illuminance distribution of each LED so as to interpolate an illuminance characteristic distribution of the cold cathode tube. Is set.
JP 2002-247296 A JP 2006-60407 A

  However, in the above-described image reading apparatus, the individual LEDs vary in light intensity within a predetermined range due to manufacturing reasons. Therefore, if the LEDs are simply arranged in an array, As a lighting device, a uniform illuminance distribution cannot be obtained. In addition, in such a state where a uniform illuminance distribution cannot be obtained by individual lighting devices, variations in illuminance occur between a plurality of lighting devices.

  The present invention has been made in view of such problems, and in an illuminating device in which light sources are arranged in the main scanning direction, the illuminance distribution of the illuminating device can be made uniform, and the illuminance between different illuminating devices. An object of the present invention is to provide an illumination device, an image reading device, and an image forming apparatus that can prevent the image from becoming non-uniform.

  According to the first aspect of the present invention, there is provided an illuminating apparatus including a light illuminator formed by arranging a plurality of light-emitting elements, wherein the light illuminant is light emission classified into different levels based on a reference value of luminous intensity. It is an illuminating device characterized in that elements are arranged based on a predetermined rule.

  According to a second aspect of the present invention, in the illumination device, the light irradiator is configured by alternately arranging light emitting elements having a light intensity higher than a predetermined reference value of light intensity and light emitting elements having a low light intensity. Claim.

  According to a third aspect of the present invention, in the illumination device according to the first aspect, the light illuminator is configured by arranging the light emitting elements classified into the different levels at predetermined intervals determined according to the respective levels. It is characterized by that.

  According to a fourth aspect of the present invention, in the illumination device according to the first aspect, the light irradiator has a light emitting element having a light intensity lower than a reference value of the predetermined light intensity and a light emitting element having a high light intensity arranged in a column. It arrange | positions in the vicinity of the both ends of.

  According to a fifth aspect of the present invention, in the illumination device according to any one of the first to fourth aspects, the light emitting elements arranged in groups and arranged in a predetermined order are driven by a driving device capable of adjusting the luminous intensity for each group. It is characterized by that.

  A sixth aspect of the present invention is the illumination device according to any one of the first to fifth aspects, a traveling body on which the light irradiating body is disposed, an optical element that forms an image of reflected light from the document on an image sensor. An image reading apparatus comprising: an image pickup device that converts an amount of reflected light into an image signal.

  A seventh aspect of the present invention is an image forming apparatus comprising the image reading device according to the sixth aspect.

  According to the present invention, since the light emitting elements classified into different levels based on the reference value of the luminous intensity are arranged based on a predetermined rule, the individual different luminous intensity of the light emitting elements is averaged and the location of the lighting device In addition to preventing uneven distribution of the amount of light due to the light, there is an effect that the difference in luminous intensity between different illumination devices can be reduced.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

  Hereinafter, an image forming apparatus according to an embodiment will be described. FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus according to the embodiment, and FIG. 2 is an enlarged cross-sectional view showing the configuration of the image reading apparatus shown in FIG.

  The image forming apparatus 10 mainly includes an image reading device 11 that reads a document, an image forming unit 12 that forms an image, an automatic document feeder (ADF) 13, and a document discharge tray 14 that stacks documents sent from the ADF 13. A paper feed unit 19 having paper feed cassettes 15 to 18 and a paper discharge unit (discharge tray 20) for stacking recording paper.

  When the document D is set on the document table 21 of the ADF 13 and a print key is pressed by an operation unit (not shown), the uppermost document D is sent out in the direction of the arrow B1 by the rotation of the pickup roller 22, As the document conveying belt 23 rotates, the paper is fed onto the contact glass 24 fixed to the image reading device 11 and stops there. The image of the document D placed on the contact glass 24 is read by the image reading device 11 located between the image forming unit 12 and the contact glass 24. The image reading device 11 forms a light irradiation unit 25 that is an illuminating device that illuminates a document D on a contact glass 24, an optical system 26 that includes a plurality of mirrors for polarizing a document image, a lens 27, and a document image. A light conversion element 28 comprising a CCD or the like is provided. After the image reading is completed, the document D is transported in the direction of the arrow B2 by the rotation of the document transport belt 23 and discharged onto the document discharge tray 14. In this way, the document D is fed one by one onto the contact glass 24 and the document image is read by the image reading device 11.

  On the other hand, inside the image forming unit 12, a photoconductor 30 as an image carrier is disposed. The photoconductor 30 is rotated in the clockwise direction in the figure, and the charging device 31 charges the surface to a predetermined potential. Further, the writing unit 32 emits a laser beam L which is light-modulated in accordance with image information read by the image reading device 11, and the surface of the charged photoreceptor 30 is exposed with the laser beam L, whereby the photosensitive unit 30 is exposed to light. An electrostatic latent image is formed on the surface of the body 30. When the electrostatic latent image passes through the developing device 33, the electrostatic latent image is transferred to the recording medium P fed between the photosensitive member 30 and the transfer device 34 by the opposing transfer device 34. The surface of the photoconductor 30 after the toner image is transferred is cleaned by a cleaning device 35.

  The plurality of paper feed cassettes 15 to 18 arranged at the lower part of the image forming unit 12 contain recording media P such as paper, and the recording media P is fed from any of the paper feed cassettes 15 to 18 in the direction of arrow B3. The toner image formed on the surface of the photoreceptor 30 as described above is transferred onto the surface of the recording medium P. Next, the recording medium P is passed through the fixing device 36 in the image forming unit 12 as indicated by an arrow B4, and the toner image transferred to the surface of the recording medium P by the action of heat and pressure is fixed. The recording medium P that has passed through the fixing device 36 is conveyed by the discharge roller pair 37, discharged to the discharge tray 20 as indicated by an arrow B5, and stacked.

  Next, the image reading apparatus 11 according to this example will be described. As shown in FIG. 2, the image reading device 11 includes a light irradiation unit 25 as a light irradiation body. The image reading device 11 irradiates the document D on the contact glass 24 with light by the light irradiation unit 25 and the counter reflector 102, and the reflected light is held by the first carriage 100 and the second mirror 101. The light is deflected by the second mirror 201 and the third mirror 202 held by the carriage 200, guided to the light conversion element 28 through the lens 27, and converted into an electric signal by the light conversion element 28. In the first carriage 100 and the second carriage 200, when the scanning speed of the first carriage is s, the second carriage scans at the speed of s / 2 and scans the document D. The counter reflection plate 102 is used to eliminate shadows that occur when the cut and pasted original is read, and is arranged as necessary.

  FIG. 3 is an enlarged sectional view showing a peripheral portion of a general first carriage, and FIG. 4 is a perspective view showing a state where the light emitting diode is attached to the substrate. The light irradiation unit 25 includes an LED array 103 composed of a light-emitting diode 104 (hereinafter referred to as LED) that is a light source and a substrate 105, and a cradle 106 that is a support member. In this example, the LED array 103 constitutes a light irradiation body. Further, the light irradiation unit 25 and the first mirror 101 are held by a base 107. Further, in this example, the LED 104 is a side view type LED arranged so as to emit light in the mounting plane direction of the substrate 105, and as shown in FIG. 4, the substrate has a light emitting surface 108 in a direction orthogonal to the mounting plane. 105 are arranged in a line.

[Example 1]
Next, the configuration of the LED array of the illumination device according to the embodiment will be described. FIG. 5 is a perspective view showing an arrangement state of light emitting diodes on a substrate in the illumination apparatus according to the first embodiment. In this embodiment, the predetermined light intensity is used as a reference value, and the light-emitting diodes 104 are classified into two light emitting diodes whose rank is higher (rank A) and lower (rank B) than the reference value. When the LED array 103 is configured, the LEDs 104 divided into two ranks are arranged on the substrate 105 so that the ones with high and low luminosity are alternately arranged.

  In the example shown in FIG. 5, the LED array 103 is configured by alternately arranging LED light emitting elements A having high luminous intensity and LED light emitting elements B having low luminous intensity one by one on the substrate 105.

  According to the present embodiment, since the low-luminance LEDs and the high-luminance LEDs are alternately arranged, the distribution of the luminous intensity resulting from the manufacture of the LEDs can be averaged, and the amount of light varies depending on the location of the LED array. Can be prevented. In addition, since the light distribution of the LED array can be made uniform, the non-uniformity of the luminous intensity between the different LED arrays as parts can be reduced.

[Example 2]
Next, a second embodiment will be described. FIG. 6 is a perspective view showing an arrangement state of light emitting diodes on a substrate in the illumination apparatus according to the second embodiment. In this embodiment, the LEDs are classified into five ranks based on the reference values of the four luminous intensity. In this example, the LEDs having the highest luminous intensity to the lowest LED are divided into rank A, rank B, rank C, rank D, and rank E in order, and these are arranged in a predetermined order.

  In this example, LEDs are arranged in the order of rank A, rank D, rank C, rank B, rank E, rank A, rank D, rank C,. This arrangement is intended to make the sum of the amounts of light between adjacent LEDs as uniform as possible. Note that the order of arrangement is not limited to that shown here. In addition, this example assumes that the ranks A to E can be manufactured in the same amount, but different arrangements are more appropriate when there is a difference in the distribution for each rank due to manufacturing errors.

  According to the present embodiment, by classifying the LEDs more finely, it is possible to average the light intensity distribution resulting from the manufacture of the LEDs, and to prevent unevenness in the amount of light depending on the location of the LED array. In addition, since the light distribution of the LED array can be made uniform, the non-uniformity of the luminous intensity between the different LED arrays as parts can be reduced.

Example 3
Next, a third embodiment will be described. FIG. 7 is a perspective view showing an arrangement state of light emitting diodes on a substrate in the illumination apparatus according to the third embodiment. In the present embodiment, the predetermined light intensity is set as a reference value, and the light emitting diodes 104 are classified into two light intensity diodes that are higher than the reference value (rank A) and lower light (rank B), and these are arranged. The intervals are not made equal.

  That is, in this example, two LEDs of rank B are arranged between two LEDs of rank A, the distance between the LEDs of rank A and B is L1, and the LEDs of rank B are The interval dimension between them is L2, and L1> L2.

  According to the present embodiment, the distribution of the luminous intensity resulting from the manufacture of the LEDs can be averaged by changing and arranging the intervals corresponding to the brightness of the light emitting elements, and the unevenness in the amount of light depending on the location of the LED array. Can be prevented. Moreover, since the light distribution of the LED array can be made uniform, the non-uniformity of the luminous intensity between the different LED arrays as parts can be reduced. In addition, while ranking according to the luminous intensity of LED can be increased, the number of steps of the LED mounting interval can be increased.

Example 4
Next, a fourth embodiment will be described. FIG. 8 is a perspective view showing an arrangement state of light emitting diodes on a substrate in the illumination apparatus according to the fourth embodiment. In this embodiment, the LEDs are divided into five ranks based on the reference values of the four luminosities. In this example, LEDs having the highest luminous intensity are classified into rank A, rank B, rank C, rank D, and rank E sequentially from the LED having the highest luminous intensity. (Rank A) is arranged near both ends of the array arrangement, LEDs with low luminous intensity (Rank E) are arranged near the center, and LEDs of rank B, rank C, and rank D are sequentially arranged between them. ing.

  In general, the LED array can obtain a higher amount of light at both ends than at the center. In general, when an image is read by a line sensor such as a CCD in a reduction optical system using a lens, even if the illuminance on the document surface is made uniform, the light quantity at both ends of the image surface is reduced compared to the central portion. This is unavoidable in a reduction optical system using a lens. Therefore, usually, a diaphragm is provided in front of the lens to cut the light at the center so that the light quantity is uniform on the image plane. According to the LED array of the present embodiment, the amount of light at both ends of the document surface is increased, so that at least correction by the diaphragm can be performed uniformly.

Example 5
Next, a fifth embodiment will be described. FIG. 9 is a circuit diagram showing a light emitting diode driving apparatus in the illumination apparatus according to the fifth embodiment. In this example, LEDs that are ranked according to light intensity are grouped, and each grouped LED is driven by a drive circuit that can control the light quantity of the LEDs. The LED array driven by the driving device according to the present example is intended for those between the first to fourth embodiments, and can drive an LED array in which LEDs are arranged on a substrate based on other rules. it can.

  The drive device includes a current adjustment resistor that can adjust the current of LEDs belonging to a plurality of groups for each group, and can adjust the value of the current flowing through the LEDs of each group, thereby eliminating the difference in light quantity between the groups of LEDs. it can. For this reason, uniform light quantity distribution is realizable in the whole LED array. In the example shown in FIG. 8, four groups having three LEDs 104 and a resistor 110 are controlled. Note that the transistor 111 is a lighting control transistor.

  Note that the driving circuit is not limited to the example given here as long as it is a circuit capable of constant current control, and other circuits such as a high-frequency lighting circuit can be used as long as it can be controlled for each group.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment. It is an expanded sectional view which shows the structure of the image reading apparatus shown in FIG. It is an expanded sectional view showing the peripheral part of a common 1st carriage. It is a perspective view which shows the attachment state to the board | substrate of a light emitting diode. It is a perspective view which shows the arrangement | positioning state to the board | substrate of the light emitting diode in the illuminating device which concerns on a 1st Example. It is a perspective view which shows the arrangement | positioning state to the board | substrate of the light emitting diode in the illuminating device which concerns on a 2nd Example. It is a perspective view which shows the arrangement | positioning state to the board | substrate of the light emitting diode in the illuminating device which concerns on a 3rd Example. It is a circuit diagram which shows the drive device of the light emitting diode in the illuminating device which concerns on a 4th Example. It is a perspective view which shows the arrangement | positioning state to the board | substrate of the light emitting diode in the illuminating device which concerns on a 5th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Image reading apparatus 12 Image forming part 13 Automatic document feeder (ADF)
14 Document discharge trays 15 to 18 Paper feed cassette 19 Paper feed unit 20 Paper discharge tray 21 Document tray 22 Pickup roller 23 Document transport belt 24 Contact glass 25 Light irradiation unit 26 Optical system 27 Lens 28 Light conversion element 30 Photoconductor 31 Charging Device 32 Unit 33 Developing device 34 Transfer device 35 Cleaning device 36 Fixing device 37 Discharge roller pair 100 First carriage 101 First mirror 102 Opposing reflector 103 LED array 104 Light emitting diode 105 Substrate 107 Base 110 Resistance 111 Transistor 200 First 2 carriage 201 2nd mirror 202 3rd mirror

Claims (7)

In an illumination device including a light illuminator formed by arranging a plurality of light emitting elements in a row,
The illuminating device is configured by arranging light emitting elements classified into different levels based on a reference value of luminous intensity based on a predetermined rule.   The lighting device according to claim 1, wherein the light irradiator is configured by alternately arranging light emitting elements having a higher luminous intensity than a reference value of a predetermined luminous intensity and light emitting elements having a lower luminous intensity.   The illuminating device according to claim 1, wherein the light irradiator is configured by arranging the light emitting elements classified into the different levels at predetermined intervals determined according to each level.   2. The light irradiator includes a light emitting element having a light intensity lower than a reference value of the predetermined light intensity and a light emitting element having a high light intensity disposed in the vicinity of both ends of the line. Lighting equipment.   The lighting device according to any one of claims 1 to 4, wherein the light-emitting elements arranged in a predetermined order by being divided into groups are driven by a driving device capable of adjusting the luminous intensity for each group.   An illumination device according to any one of claims 1 to 5, a traveling body on which the light irradiation body is disposed, an optical element that forms an image of reflected light from the document on an image sensor, and a light amount of the reflected light. An image reading apparatus comprising: an image sensor that converts an image signal. An image forming apparatus comprising the image reading apparatus according to claim 6.