JP2013174924A - Recording material surface detection device and image formation device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording material surface detection device that can detect a surface state of a recording material without depending on a fiber orientation direction of the recording material with high accuracy, and to provide an image formation device provided with the recording material surface detection device.SOLUTION: The recording material surface detection device comprises: irradiation LEDs 42A and 42B; a CMOS area sensor 43A that photographs light irradiation area as a surface area; and a drive/calculation part 40C that detects information about an uneven state of a surface of a recording material P. The irradiation LEDs 42A and 42B are arranged such that a straight line connecting the irradiation LED 42A to the light irradiation area and projected on the recording material P and a straight line connecting the irradiation LED 42B to the light irradiation area and projected on the recording material P form an intersectional relation. When the light irradiation area is photographed as the surface image, a timing for each of the irradiation LEDs 42A and 42B to emit light or not to emit the light is different from each other. Thus, based on the surface image obtained at respective timings, the surface state of the recording material P is detected.

Description

  The present invention relates to a recording material surface detection device that detects the surface state of a recording material based on a surface image picked up by an image pickup means, and an image forming device that controls image forming conditions based on the detection result. .

  Image forming apparatuses such as copying machines and laser beam printers transfer a developer image visualized by a developing device to a recording material under a predetermined transfer condition, and heat the recording material with the developer image transferred under a predetermined fixing condition. By applying pressure, an image is formed on the recording material.

  In such an image forming apparatus, for example, the size and type of recording paper as a recording material (hereinafter also referred to as paper type) are set by a user on an operation panel or the like provided in the main body of the image forming apparatus. In accordance with the setting, transfer conditions (for example, transfer bias and recording paper conveyance speed during transfer) and fixing conditions (for example, fixing temperature and recording paper conveyance speed during fixing) are controlled.

  In recent years, a sensor for detecting the surface unevenness of the recording material (hereinafter referred to as the surface state) is provided inside the image forming apparatus, and the type of the recording material is determined based on the detection result of the sensor, and the transfer condition or fixing condition A method for controlling image forming conditions such as the above has been proposed.

  For example, Patent Documents 1 and 2 disclose configurations in which the surface state of a recording material is detected by imaging the surface of the recording material with a CMOS sensor as an imaging unit. Patent Document 3 discloses a configuration in which the thickness of the recording material is determined by providing a light source at a position facing the sensor as the determining means, and detecting the transmitted light transmitted through the recording material. Yes. Further, Patent Document 4 discloses a configuration in which the surface state and thickness of the recording material are recognized by irradiating the recording material with ultrasonic waves and detecting the reflectance and transmittance.

JP 2002-182518 A JP 2004-38879 A JP 2001-139189 A Japanese Patent Laid-Open No. 2004-219856

  As described above, many configurations for detecting the surface state of the recording material have been proposed, but according to the study by the present inventors, among such configurations, for example, a configuration as described in Patent Document 1 is provided. However, it is known that the detection accuracy of the surface state is superior to the other configurations. That is, the method of imaging the surface state of the recording material with an image sensor such as a CMOS sensor directly captures the shadow caused by the unevenness of the surface of the recording material. It is known that the detection accuracy is better than that. In particular, as in the case of discriminating between coated paper and non-coated paper, excellent discrimination accuracy is obtained in discriminating recording materials in which the presence or absence of irregularities or the size and depth thereof can be visually discriminated clearly.

However, for example, in general office paper as a recording material, the appearance of shading caused by the irregularities on the surface of the paper may vary greatly depending on the fiber orientation direction (perforation direction) of the paper. There is a risk of reducing accuracy. That is, when light is irradiated from a direction perpendicular to the fiber orientation direction of the recording material, a high-contrast photographic image is obtained in which the irregularities on the surface of the recording material are emphasized. On the other hand, when light is irradiated from the same direction as the fiber orientation direction, shadows due to unevenness are difficult to occur and a captured image with low contrast is obtained. For this reason, even if the recording material is the same, if the relationship between the light irradiation direction and the fiber orientation direction of the recording material is different, the difference in contrast of the photographed image becomes severe. For example, the coated paper is misidentified as non-coated paper. There is a risk of misclassifying non-coated paper as coated paper.

  Therefore, the present invention has been made to solve the above problems, and a recording material surface detection device capable of detecting a surface state with high accuracy without depending on the fiber orientation direction of the recording material, and the same An object of the present invention is to provide an image forming apparatus.

In order to achieve the above object, the present invention provides:
A recording material surface detection apparatus for detecting a surface state of a recording material, the first light source and the second light source for irradiating light on the surface of the recording material, and the first light source and the second light source on the surface of the recording material Imaging means for imaging the light irradiation area irradiated with the light as a surface image of the recording material, and detection means for detecting information relating to the uneven state of the surface of the recording material based on the surface image captured by the imaging means; In a state where the recording material is irradiated with light, a straight line obtained by projecting a straight line connecting the first light source and the light irradiation region onto the recording material, and the second light source and the light irradiation region The first light source and the second light source are arranged so that a straight line formed by projecting a connecting straight line onto a recording material intersects, and when the light irradiation region is imaged as a surface image, the first light source is captured. At the timing of the first light Is turned on, the second light source is turned off to perform imaging, and then, at a second timing, the first light source is turned off, the second light source is turned on to perform imaging, and the first timing, and The surface state of the recording material is detected based on the surface image obtained at each of the second timings.

  As described above, the present invention provides a recording material surface detection device that can accurately detect the surface state without depending on the fiber orientation direction of the recording material, and an image forming apparatus including the same. Is possible.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. 1 is a schematic configuration diagram of a recording material surface detection apparatus according to a first embodiment. FIG. 3 is a view showing a photographed image obtained by the recording material surface detection apparatus according to the first embodiment. The histogram showing the brightness information of the surface uneven | corrugated image in 1st Embodiment. The figure which shows the detection result of the brightness difference (DELTA) I detected in 1st Embodiment. The schematic block diagram of the recording material surface detection apparatus which concerns on 2nd Embodiment. The figure which shows the light emission timing in 2nd Embodiment, and a light reception timing. The figure which shows the picked-up image obtained by the recording material surface detection apparatus which concerns on 2nd Embodiment. FIG. 9 is a schematic configuration diagram of a recording material surface detection apparatus according to a third embodiment. The schematic block diagram of the light guide which concerns on 3rd Embodiment. The top view of the recording material surface detection apparatus in a comparative example. The figure which shows the detection result of a recording material surface detection apparatus.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail based on embodiments with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

<First Embodiment>
With reference to FIGS. 1 to 3, a recording material surface detection apparatus according to a first embodiment to which the present invention is applicable and an image forming apparatus including the same will be described.

[Configuration of image forming apparatus]
The recording material surface detection apparatus according to this embodiment can be applied to, for example, an electrophotographic color image forming apparatus. FIG. 1 shows a schematic configuration of a tandem color image forming apparatus employing an intermediate transfer belt as an image forming apparatus according to the present embodiment.

  The image forming apparatus includes a station corresponding to each color of Y (yellow), M (magenta), C (cyan), and Bk (black). These stations are provided with photosensitive drums (photoconductors) 1Y, 1M, 1C, and 1Bk that are configured to be rotatable. Around the photosensitive drum 1, charging rollers 2Y, 2M, 2C, and 2Bk as primary charging means, exposure scanner units 11Y, 11M, 11C, and 11Bk, and developing devices 8Y, 8M, 8C, and 8Bk as developing means are provided. Is provided. Each of the photosensitive drum body 1, the charging roller 2, and the developing device 8 are integrated, and attached to the image forming apparatus main body in the form of toner cartridges 31Y, 31M, 31C, and 31Bk that are detachable.

  The photosensitive drums 1Y, 1M, 1C, and 1Bk are in contact with the intermediate transfer belt 24. The intermediate transfer belt 24 is driven by a driving roller 23 and is stretched by a tension roller 13 with a predetermined tension. Further, the secondary transfer counter roller 26, the primary transfer rollers 4Y, 4M, 4C, 4Bk, and the secondary transfer roller 25 are in contact with the intermediate transfer belt 24. A fixing unit 21 for fixing the toner image on the recording material P is provided on the downstream side in the transport direction from the nip portion (secondary transfer nip portion) between the secondary transfer roller 25 and the secondary transfer counter roller 26. ing. A feeding cassette 15 capable of stacking a plurality of recording materials P is provided below the apparatus main body. The operations of these members related to image formation are controlled by the control unit 10.

  The photosensitive drums 1Y, 1M, 1C, and 1Bk are configured by applying an organic optical transmission layer on the outer periphery of an aluminum cylinder, and are rotated by a driving force of a driving motor (not shown). 1M, 1C, and 1Bk are rotated clockwise according to the image forming operation. When the control unit 10 receives the image signal, the recording material P is fed from the feeding cassette 15 into the image forming apparatus by feeding rollers 17 and 18, and in order to synchronize with an image forming operation described later, a registration roller pair 19a, It is pinched by 19b, stops in that state, and waits.

  On the other hand, in accordance with the received image signal, the control unit 10 has the photosensitive drums 1Y, 1M, 1C, and 1Bk charged to a constant potential by the charging rollers 2Y, 2M, 2C, and 2Bk by the exposure scanner units 11Y, 11M, 11C, and 11Bk. An electrostatic latent image is formed on the surface. The electrostatic latent image is developed as a toner image of each color by the developing devices 8Y, 8M, 8C, and 8Bk at each station. Each developing device 8 is provided with sleeves 5Y, 5M, 5C, and 5Bk, and is applied with a developing bias for visualizing the electrostatic latent image.

  The intermediate transfer belt 24 rotates in synchronization with the rotation of the photosensitive drums 1Y, 1M, 1C, and 1Bk in the counterclockwise direction while forming a color image while contacting the photosensitive drums 1Y, 1M, 1C, and 1Bk. The single color toner image on the photosensitive drum 1 is sequentially primary transferred sequentially on the intermediate transfer belt 24 by the action of the primary transfer bias applied to the primary transfer roller 4, and a multicolor toner image is formed on the intermediate transfer belt 24. The

The multicolor toner image formed on the intermediate transfer belt 24 is conveyed to a secondary transfer nip portion formed by the secondary transfer roller 25. At the same time as the multicolor toner image is conveyed to the secondary transfer nip portion, the recording material P that has been waiting while being sandwiched between the registration roller pairs 19a and 19b is conveyed to the secondary transfer nip portion. Then, the multicolor toner image on the intermediate transfer belt 24 is collectively transferred onto the recording material P by the action of the secondary transfer bias applied to the secondary transfer roller 25. The residual toner remaining on the intermediate transfer belt 24 without being transferred to the recording material P is cleaned by the cleaning means 28, and the collected transfer residual toner is stored in the cleaner container 29 as waste toner.

  The fixing unit 21 melts and fixes the multi-color toner image secondarily transferred onto the recording material P while conveying the recording material P, and includes a fixing roller 21a for heating the recording material P as shown in FIG. A pressure roller 21b that presses the recording material P against the fixing roller 21a. The fixing roller 21a and the pressure roller 21b are formed in a hollow shape, and heaters 21ah and 21bh are incorporated therein, respectively. The recording material P holding the multicolor toner image is conveyed by the fixing roller 21a and the pressure roller 21b, and heat and pressure are applied during the conveyance process, and the toner image is fixed on the surface. The recording material P on which the toner image has been fixed is discharged onto the discharge tray 16 by the discharge roller 20, and the image forming operation is completed. Note that the series of image forming operations described here are controlled by the control unit 10 provided in the image forming apparatus.

[Configuration of Recording Material Surface Detection Device]
With reference to FIG. 2, the configuration of the recording material surface detection device 40 according to the present embodiment will be described. 2A and 2B show a schematic configuration of the recording material surface detection apparatus 40 according to the present embodiment, in which FIG. 2A is a perspective view, FIG. 2B is a top view, and FIG. 2C is a cross-sectional view taken along line AA ′ in FIG. FIG.

  The recording material surface detection device 40 according to the present embodiment is installed in the recording material surface detection unit in front of the registration roller pair 19a and 19b (upstream in the transport direction) shown in FIG. The information reflecting the surface state of the recording material P conveyed to is detected. Here, the surface state of the recording material P refers to an uneven state, surface roughness, or surface smoothness of the recording material P. In the present embodiment, the detection of the surface state and the determination of the recording material P by the recording material surface detection device 40 are stopped when the recording material P is fed from the feeding cassette 15 and sandwiched between the registration roller pairs 19a and 19b. It is done while you are. Further, the control unit 10 connected to the recording material surface detection device 40 discriminates the type of the recording material P based on the detection result sent from the recording material surface detection device 40, and the optimum transfer bias / The image forming apparatus is controlled to operate by setting image forming conditions such as a fixing temperature.

  The recording material surface detection device 40 includes two irradiation LEDs 42A (first light source) and 42B (second light source) as light sources that are light irradiation means, a CMOS area sensor 43A that is imaging means, and an imaging means. An image lens 44SA. In the present embodiment, white LEDs (NSPW300DS manufactured by Nichia Corporation) having high directivity are used as the irradiation LEDs 42A and 42B.

  Of these two irradiation LEDs 42A and 42B, one is arranged so that the optical axis direction is the same as the conveyance direction of the recording material P, and the other is arranged so that the optical axis direction is perpendicular to the conveyance direction of the recording material P. ing. Further, the straight line that projects the straight line connecting the irradiation LED 42A and the light irradiation region onto the recording material P and the straight line that projects the straight line connecting the irradiation LED 42B and the light irradiation region onto the recording material P intersect. ing. The light irradiation area is irradiated with light from both the irradiation LEDs 42A and 42B. Further, the light emitted from the irradiation LEDs 42A and 42B is incident obliquely from below at an angle of 15 ° with respect to the surface of the recording material P. In this way, by irradiating light obliquely from a low angle with respect to the recording material surface, it becomes possible to make the shadow caused by the irregularities on the surface of the recording material P stand out. In addition, according to the earnest study by the present inventors, it has been found that the incident angle may be in a range from 0 ° to 20 °.

  The reflected light including the shadow information reflecting the surface state of the recording material P is collected by the imaging lens 44SA and focused on the CMOS area sensor 43A. The CMOS area sensor 43A reflects the reflected light amount for each imaged pixel area. A video voltage signal that changes according to the output is output. Upon receiving the video voltage output signal output from the CMOS area sensor 43A, the driving / calculating unit 40c performs A / D conversion on the video voltage output signal, and outputs the converted 256-gradation digital signal to the control unit 10. In the present embodiment, the effective pixel size of the CMOS area sensor 43A is 1.5 mm long × 1.5 mm wide and has a resolution of 600 dpi. Thus, in combination with the lens 44SA, an area of a predetermined size of 3.0 mm in length and 3.0 mm in width on the surface of the recording material can be imaged with a resolution of 300 dpi.

  In the present embodiment, when the surface image of the recording material P is captured, first of the two irradiation LEDs, for example, the irradiation LED 42A is turned on, and the irradiation LED 42B is turned off for the first shooting. (First timing). After that, the second shooting is performed with the irradiation LED 42A turned off and the irradiation LED 42B turned on (second timing). That is, in this embodiment, the timing of light emission of the two irradiation LEDs is shifted from each other. During the two imaging operations described here, the recording material P is held by the registration roller pairs 19a and 19b in a stopped state.

  As described above, when photographing is performed by irradiating light from two different directions with respect to the fiber orientation direction of the recording material P, the following effects can be obtained. For example, even if one optical axis matches the fiber orientation direction of the recording material P and only a photographic image having a low contrast can be obtained for the surface unevenness level, the other optical axis is perpendicular to the fiber orientation direction. Therefore, it is possible to obtain a photographic image with a high contrast reflecting the surface unevenness level. By comprehensively considering these two captured images, the surface state detection accuracy of the recording material P can be improved.

  In order to verify the effect of this embodiment, the following recording material discrimination experiment was performed using the recording material surface detection device 40 according to this embodiment and a conventional recording material surface detection device. Hereinafter, the experimental result will be described.

  First, two kinds of Ledger-sized plain papers (trade name: Xerox Business 4200 20Lb) having different fiber orientation directions were used as recording materials. One is A4 size paper (1) obtained by intentionally cutting the plain paper diagonally, and the other is A4 size paper (A4 size paper obtained by cutting in the longitudinal direction (longitudinal direction) in the fiber orientation direction ( 2). These will be described as paper (1) and paper (2). When the paper (1) was observed with a microscope, the fiber orientation direction was inclined 20 ° with respect to the longitudinal direction of the paper. That is, it can be said that the paper (1) and the paper (2) are the same type of paper but differ only in the fiber orientation direction.

  FIG. 3 shows a photographed image obtained when the surface of the paper (1) is photographed using the recording material surface detector 40 according to the present embodiment. FIG. 3A is a surface unevenness image (captured image) when the irradiation area 42 is irradiated with light from the same direction as the longitudinal direction of the paper (1) and the irradiation area is imaged with the CMOS area sensor 43A. . FIG. 3B shows a surface unevenness image when the irradiation area 42 is imaged by the CMOS area sensor 43A when light is irradiated from a direction (lateral direction) perpendicular to the vertical direction of the paper (1) by the irradiation LED 42B. Image). When the brightness information of these two images is averaged for each corresponding pixel, a composite image as shown in FIG. 3C is obtained. In this way, by combining the captured images obtained by irradiating light from two different directions, it is possible to obtain information that takes into account the fiber orientation dependence of the surface irregularities.

Further, when the brightness information (digital signal level) corresponding to these surface unevenness images is converted into a histogram, a distribution as shown in FIG. 4 is obtained. In FIG. 4, the horizontal axis represents lightness information (digital signal level) corresponding to each surface irregularity image for each class, and the vertical axis represents the number of corresponding pixels in the imaging region as a frequency.

  The control unit 10 has an average value Imax of five signals in order from the lightness information (digital signal level) having the highest lightness (high voltage), and five signals in order from the lightness lowest (voltage is low). The average value Imin is calculated. Then, a brightness difference ΔI, which is a difference between them, is obtained for each captured image.

  FIG. 5 shows the detection result of the brightness difference ΔI for the two types of paper (1) and paper (2). As shown in FIG. 5, it can be seen that the average brightness difference ΔI (ave) of each paper (1) and paper (2) converges to substantially the same value. In other words, the same light irradiation area is imaged from two different directions at different timings, the surface state is detected, and the average brightness difference ΔI (ave) is obtained, so that the recording material can be accurately obtained even when the fiber orientation directions are different. Can be determined. That is, the recording material type discrimination accuracy is improved.

  On the other hand, as a comparative example, a conventional recording material surface detection device of one light source and one imaging type as shown in FIG. The surface state of (2) was detected. Here, the irradiation LED 42 is arranged so that the optical axis of the irradiation LED 42 is inclined by 45 ° with respect to the conveyance direction of the recording material P.

  FIG. 12 shows a detection result relating to the surface state of the recording material P obtained by using a conventional recording material surface detection apparatus. According to the conventional apparatus, the difference in brightness ΔI when detecting the paper (2) cut so that the fiber orientation direction coincides with the longitudinal direction (longitudinal direction) of A4 size paper is the fiber orientation direction with respect to the longitudinal direction of the paper. Is smaller than the brightness difference ΔI when the paper (1) inclined by 20 ° is detected. In other words, in the conventional recording material surface detection device used as a comparative example, the detection result varies depending on the fiber orientation direction of the paper even though the surface image of the same recording material is detected. I understand that. On the other hand, in this embodiment, the influence of the fiber orientation direction of the paper on the detection result can be reduced, and variations in the detection result can be reduced, so that the recording material discrimination accuracy can be improved.

  In this embodiment, the irradiation LEDs 42A and 42B are used as the light source. However, for example, a xenon lamp or a halogen lamp may be used as the light source. That is, any light source can be used as long as it can emit a sufficient amount of light to highlight the shadow caused by the surface unevenness of the recording material P. Further, as the image pickup means, a CCD type sensor may be used instead of the CMOS type sensor, and another sensor may be used as long as it can reliably image the surface state of the recording material. In the above description, the irradiation LED 42A is described as the first light source, and the irradiation LED 42B is described as the second light source. However, the first light source and the second light source are not limited to this, and the irradiation LEDs 42A and 42B are sequentially arranged. Two light sources or a first light source may be used (the same applies to the second and third embodiments).

  In the present embodiment, a detection function for detecting the contrast of the surface image captured by the CMOS area sensor 43A is provided in the control unit 10 of the recording material surface detection device 40. The structure provided in the calculation part 40C may be sufficient.

  In the present embodiment, the control unit 10 controls the transfer bias or the fixing temperature based on the surface state of the recording material P detected by the recording material surface detection device 40. However, the control target is not limited to these, and the control unit 10 can control various control parameters and a series of image formation speeds (process speeds) in each process of electrostatic latent image formation and development, for example. It is. That is, the control unit 10 may control any image forming condition as long as the condition is related to an image forming operation for forming an image on a recording material.

  As described above, according to the present embodiment, a recording material surface detection device capable of accurately detecting the surface state of a recording material without depending on the fiber orientation direction of the recording material, and an image forming apparatus including the recording material surface detection device. It becomes possible to provide.

Second Embodiment
With reference to FIGS. 6-8, the recording material surface detection apparatus which concerns on 2nd Embodiment which can apply this invention, and an image forming apparatus provided with the same are demonstrated. FIG. 6 is a diagram showing a schematic configuration of the recording material surface detection apparatus according to the present embodiment, where (a) is a perspective view, (b) is a top view, and (c) is a side view. The recording material surface detection apparatus 40 includes irradiation LEDs 42A and 42B as light sources, a CMOS line sensor 43L as imaging means, and an imaging lens array 44A as imaging means. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the present embodiment, standard type bullet-type white LEDs (manufactured by ROHM Co., Ltd .: model number SLR343) are used for the irradiation LEDs 42A and 42B. As shown in FIGS. 6A and 6B, one of the irradiation LEDs 42A and 42B has the other optical axis so that the optical axis direction is + 45 ° with respect to the conveyance direction of the recording material P. It is arranged in an inverted U shape so that the direction is −45 ° with respect to the conveyance direction of the recording material P. The light emitted from these light sources irradiates the same location on a straight line perpendicular to the recording material conveyance direction on the recording material conveyance path, and is 15 from below with respect to the surface of the recording material P being conveyed. Incident at an angle of °. This incident angle may be in the range of 0 ° to 20 °.

  The CMOS line sensor 43L and the imaging lens array 44A are installed such that their longitudinal directions are orthogonal to the recording material conveyance direction. Further, the same light irradiation area on the same straight line orthogonal to the recording material conveyance direction is arranged at a position where the light can be photographed in the light irradiation area irradiated with light from the irradiation LEDs 42A and 42B.

  The reflected light including the shadow information reflecting the surface state of the recording material P is collected by the imaging lens array 44A and captured as a line image by the CMOS line sensor 43L. The CMOS line sensor 43L detects a video voltage signal that changes in accordance with the amount of reflected light for each pixel in the line imaged as a line image, and outputs the video voltage signal to the drive / calculation unit 40C. When receiving the video voltage output signal output from the CMOS line sensor 43L, the driving / calculating unit 40C as detection means performs A / D conversion on the video voltage output signal and detects the converted digital signal (lightness information).

  When discriminating the recording material P, the brightness as an area is obtained by sequentially connecting digital signals (brightness information) while performing the imaging operation for each line while moving the recording material P in the transport direction. Create information. Here, the drive / calculation unit 40C calculates a contrast (brightness difference) from a digital signal (brightness information) as an area, and outputs it to the control unit 10. That is, the drive / calculation unit 40C as the detection unit detects the contrast calculated from the lightness information of the area where the line images captured by the CMOS line sensor 43L as the imaging unit are sequentially joined. In the present embodiment, the CMOS line sensor 43L and the drive / calculation unit 40C are provided in the recording material surface detection device 40.

  The CMOS line sensor 43L in this embodiment has an effective pixel length (longitudinal direction) of 10 mm and a resolution of 600 dpi. While the recording material P is conveyed to the secondary transfer nip portion while being sandwiched between the registration roller pairs 19a and 19b, the control unit 10 moves the recording material P by 5 mm in the conveyance direction for each line described above. An imaging operation is being performed.

Further, in the present embodiment, the illumination LEDs 42A and 42B are turned on / off (light emission timing) and the light reception timing of the CMOS line sensor 43L is controlled as shown in FIG. When imaging the light irradiation region, first, the irradiation LED 42A is turned on, and the irradiation LED 42B is turned off, and the first imaging is performed (first timing). In the first imaging, a predetermined area of 10 mm × 0.042 mm (one pixel of 600 dpi) on the recording material P is imaged. Subsequently, when the recording material P moves 0.021 mm, the irradiation LED 42A is turned off, the irradiation 42B is turned on, and the second imaging (10 mm × 0.042 m) is performed.
m) is performed (second timing). Subsequently, the recording material moves 0.021 mm, the irradiation LED 42A is turned on, the irradiation LED 42B is turned off, and the third imaging is performed. Thereafter, the imaging operation is repeated.

  While performing such a series of imaging operations, the recording material P is gradually moved in the transport direction, and the control unit 10 receives the received digital signal when the irradiation LED 42A is lit and when the irradiation LED 42B is lit. Sequentially connect them while separating them. That is, the control unit 10 performs the above-described series of imaging operations while moving the recording material P by 10 mm in the transport direction while the recording material P is held between the registration roller pairs 19a and 19b and is on standby. As a result, two captured images of 10 mm long × 10 mm wide obtained by irradiating light from two different directions on the same area on the recording material P can be obtained with a resolution of 600 dpi × 600 dpi.

  FIG. 8 shows a photographed image obtained by the recording material surface detection device 40 according to the present embodiment. For example, two surface images obtained when an A4 size paper (1) obtained by a method similar to that described in the first embodiment is detected are as shown in FIGS. 7 (a) and 7 (b). become. Then, the drive / calculation unit 40C detects the surface state of the recording material P by using the same analysis method as described in the first embodiment, determines the type of the recording material, and the control unit 10 determines based on the determination result. Image forming conditions such as optimum transfer bias and fixing temperature are controlled.

  As described above, in the present embodiment, the line sensor 43L is used as the imaging unit, and imaging is performed while the irradiation LEDs 42A and 42B are alternately lit while the recording material P is conveyed. Therefore, since the photographed image can be obtained by irradiating the recording material P surface with light from two different directions, the detection accuracy of the recording material P can be improved as in the first embodiment. Then, the type of the recording material is discriminated from the detection result, and the optimum image forming conditions (for example, transfer conditions, fixing conditions, etc.) can be set.

  As described above, according to the present embodiment, a recording material surface detection device capable of accurately detecting the surface state of a recording material without depending on the fiber orientation direction of the recording material, and an image forming apparatus including the recording material surface detection device. It becomes possible to provide.

<Third Embodiment>
With reference to FIGS. 9 and 10, a recording material surface detection apparatus according to a third embodiment to which the present invention is applicable and an image forming apparatus including the same will be described. FIG. 9 is a diagram showing a schematic configuration of the recording material surface detection apparatus according to the present embodiment, in which (a) is a perspective view, (b) is a top view, and (c) is a side view. The recording material surface detection apparatus 40 includes irradiation LEDs 42A and 42B as light sources, a CMOS line sensor 43L as imaging means, and an imaging lens array 44A as imaging means. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

The recording material surface detection device 40 according to this embodiment is characterized in that a light guide 45 is provided as a light guide member that guides the light emitted from the irradiation LEDs 42A and 42B to the surface of the recording material. As the irradiation LEDs 42A and 42B, standard-type chip-type white LEDs (NSSW100CT manufactured by Nichia Corporation) are used. The CMOS line sensor 43L and the imaging lens array 44A are installed so that the longitudinal direction thereof is orthogonal to the recording material conveyance direction so that the same light irradiation area irradiated by the irradiation LEDs 42A and 42B can be photographed. . With such a configuration, as described in the second embodiment, the illumination LEDs 42A and 42B are turned on and off at different timings, and an image similar to the above can be obtained.

  FIG. 10 ((a) is a front view and (b) is a side view) shows a schematic configuration diagram of the light guide 45. As shown in the drawing, the surface of the light guide 45 on which light from the irradiation LEDs 42A and 42B is incident (hereinafter referred to as an incident portion) has a lens structure with a curved section. Thereby, the light incident on the light guide 45 from the incident part travels through the light guide 45 in a state where the light beams are aligned in parallel. After that, the light is emitted from the light guide 45 and irradiated to the same spot on the same straight line orthogonal to the recording material feeding direction on the surface of the recording material P at an incident angle of 15 ° from below with respect to the surface of the recording material P. The incident angle may be in the range of 0 ° to 20 °.

  In this way, by irradiating the recording material surface with light from the irradiation LEDs 42A and 42B using the light guide 45, the optical path is perpendicular to the recording material conveyance direction (normal direction of the recording material P). You can earn long. Therefore, the recording material surface detection device 40 can be downsized. For example, compared with the recording material surface detection apparatus (FIG. 6) according to the second embodiment described above, the apparatus width can be reduced by about 40%.

  Further, by using the light guide 45, it is possible to install inexpensive chip-type LEDs as the irradiation LEDs 42A and 42B on the same substrate as the CMOS line sensor 43L. Further, since the incident portion of the light guide 45 has a curvature, it becomes possible to collect the light from the irradiation LEDs 42A and 42B and irradiate the surface of the recording material, and to improve the S / N ratio. A sufficient amount of light can be secured for speeding up.

  Further, by making the incident portion of the light guide 45 into the lens shape shown in FIG. 10, it is possible to reduce the distance between the two irradiation LEDs 42A and 42B, and to further reduce the size of the recording material surface detection device 40. It becomes possible. For example, in the configuration shown in FIG. 10, the apparatus width can be halved compared to the configuration in FIG. 6 (second embodiment).

  In this embodiment, the irradiation LEDs 42A and 42B are used as the light source. However, for example, a xenon lamp or a halogen lamp may be used as the light source. That is, any light source can be used as long as it can emit a sufficient amount of light to highlight the shadow caused by the surface unevenness of the recording material P. Further, as the image pickup means, a CCD type sensor may be used instead of the CMOS type sensor, and another sensor may be used as long as it can reliably image the surface state of the recording material.

  In the present embodiment, the control unit 10 controls the transfer bias or the fixing temperature based on the surface state of the recording material P detected by the recording material surface detection device 40. However, the control target is not limited to these, and the control unit 10 can control various control parameters and a series of image formation speeds (process speeds) in each process of electrostatic latent image formation and development, for example. It is. That is, the control unit 10 may control any image forming condition as long as the condition is related to an image forming operation for forming an image on a recording material.

  As described above, according to the present embodiment, a recording material surface detection device capable of accurately detecting the surface state of a recording material without depending on the fiber orientation direction of the recording material, and an image forming apparatus including the recording material surface detection device. It becomes possible to provide.

10 Control Unit 40 Recording Material Surface Detection Device 40C Drive / Calculation Unit (Detection Unit)
42A LED for irradiation (first light source)
42B LED for irradiation (second light source)
43A CMOS area sensor (imaging means)
43L CMOS line sensor (imaging means)
44A Imaging lens array (imaging means)

Claims (4)

A recording material surface detection device for detecting a surface state of a recording material,
A first light source and a second light source for irradiating light on the surface of the recording material;
Imaging means for imaging a light irradiation region irradiated with light from the first light source and the second light source on the surface of the recording material as a surface image of the recording material;
Detecting means for detecting information on the uneven state of the surface of the recording material based on the surface image imaged by the imaging means,
In a state where the recording material is irradiated with light,
A straight line obtained by projecting a straight line connecting the first light source and the light irradiation region onto the recording material;
A straight line obtained by projecting a straight line connecting the second light source and the light irradiation region onto the recording material;
The first light source and the second light source are arranged so as to intersect each other,
When capturing the light irradiation area as a surface image,
In the first timing,
The first light source is turned on, the second light source is turned off and imaging is performed, and then
In the second timing,
The first light source is turned off, the second light source is turned on to perform imaging,
A recording material surface detection apparatus that detects a surface state of a recording material based on surface images obtained at each of a first timing and a second timing. The imaging means includes
The recording material surface detection apparatus according to claim 1, wherein the recording material surface detection apparatus is an area sensor that captures an area of a predetermined size in the light irradiation region as a surface image. The detection means includes
The recording material surface detection apparatus according to claim 1, wherein a contrast of a surface image captured by the imaging unit is detected. Image forming means for forming an image on a recording material;
A first light source and a second light source for irradiating light on the surface of the recording material;
Imaging means for imaging a light irradiation region irradiated with light from the first light source and the second light source on the surface of the recording material as a surface image of the recording material;
Detecting means for detecting information related to the uneven state of the surface of the recording material based on the surface image imaged by the imaging means;
Control means for controlling the image forming conditions of the image forming means based on information relating to the uneven state of the surface of the recording material detected by the detecting means;
In an image forming apparatus having
In a state where the recording material is irradiated with light,
A straight line obtained by projecting a straight line connecting the first light source and the light irradiation region onto the recording material;
A straight line obtained by projecting a straight line connecting the second light source and the light irradiation region onto the recording material;
The first light source and the second light source are arranged so as to intersect each other,
When capturing the light irradiation area as a surface image,
In the first timing,
The first light source is turned on, the second light source is turned off and imaging is performed, and then
In the second timing,
The first light source is turned off, the second light source is turned on to perform imaging,
Based on the surface images obtained at each of the first timing and the second timing, the surface state of the recording material is detected,
An image forming apparatus, wherein the control unit controls the image forming conditions based on a detection result.

Images