JP2015064324A - Moving member detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving member detection apparatus configured to accurately detect actual speed of a moving member in a short time regardless of temperature change or the like, and an image forming apparatus including the moving member detection apparatus.SOLUTION: A moving member detection apparatus 50 sets predetermined two spots, a position A and a position B, for a moving member E. Imaging lenses 12A, 12B are arranged in the positions A, B, respectively. An area sensor 11 is formed by arranging an imaging element 112 in one silicon substrate 111. The position A is irradiated by a light source 51A. The position B is irradiated by a light source 51B. An image of the position A is imaged by the imaging lens 12A. An image of the position B is imaged by the imaging lens 12B. The image of the position A and the image of the position B are captured with a time difference Δt. An actual speed of the moving member E is determined on the basis of a correlation between the image of the position A and the image of the position B.

Description

  The present invention relates to a moving member detection device that detects an actual speed of a moving member, a belt conveyance device having the moving member detection device, and an image forming apparatus.

  In recent years, color image forming apparatuses are so-called tandems in which four photoconductors (image carriers) corresponding to toners of four colors (black, cyan, magenta, and yellow) are arranged in parallel to meet the demand for higher speed. The method has become mainstream. In the tandem method, each color toner image developed on each photoconductor needs to be finally superimposed on a recording medium such as paper (standard paper, postcard, cardboard, OHP sheet, etc.). There are two methods: a direct transfer method that directly superimposes on a recording medium, and an intermediate transfer belt method that uses an intermediate transfer belt to superimpose toner images of each color on the intermediate transfer belt and then transfers them onto the recording medium in a batch. is there. If the conveyance belt for feeding a recording medium such as paper is not driven in the direct transfer method and the intermediate transfer belt is driven with high accuracy in the intermediate transfer belt method, color misregistration occurs.

  In order to drive the intermediate transfer belt with high accuracy, for example, Japanese Patent No. 4545580 (Patent Document 1), Japanese Patent Application Laid-Open No. 2009-15240 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2010-55064 (Patent Document). As disclosed in 3), there is a technique for detecting the speed of a moving member such as an intermediate transfer belt.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2009-15240, when a velocity vector of speckle is detected and used for speed control based on the result, the velocity is calculated from the displacement of a minute section, Since the calculated speed is discretized depending on the pixel size, it is difficult to detect the speed with high accuracy, and when the belt conveyance position is calculated by integrating the speed, there is a problem that errors cannot be integrated and accurate positioning cannot be performed. It was. In addition, if the distance between the CMOS sensor and the imaging lens or the distance between the imaging lens and the object (moving member) changes due to temperature characteristics and detection distance changes, the imaging magnification changes, resulting in a measurement error in the measurement speed. there were.

  The present invention provides a high-accuracy moving speed without causing a measurement error even if the distance between the CMOS sensor of the area sensor and the imaging lens or the distance between the imaging lens and the moving member changes due to a change in temperature characteristics or a detection distance. It is an object of the present invention to provide a moving member detection device capable of measuring the above.

  The moving member detection apparatus according to claim 1 is a light source that irradiates a detection position of the moving member with a light beam, an image acquisition unit that acquires image data from the detection position of the moving member, and a movement of the moving member from the image data. It is a moving member detection apparatus provided with the speed calculating means which calculates speed. The image acquisition means includes an area sensor having at least two imaging areas on an imaging element formed on one substrate. In addition, the image acquisition means includes two imaging lenses that are arranged opposite to the A position and the B position, which are two positions in the moving direction of the moving member, and each form an image in the imaging area of the area sensor. Is provided. The image acquisition means includes area sensor control means for acquiring image data from the area sensor at a set timing. The image acquisition means acquires B position image data at the B position when the moving member moves to the B position after acquiring the A position image data at the A position. The speed calculation means calculates a moving speed of the moving member from the A position image data and the B position image data.

  According to the moving member detection device of claim 1, the A position and the B position are determined with respect to the moving member by the area sensor and the imaging lens having at least two imaging regions on the imaging element formed on one substrate. Two speckle images, for example, are acquired. The movement between them was calculated. And since it has a configuration that has an imaging system with multiple imaging lenses in one area sensor, it can improve the detection accuracy of the surface speed of the intermediate transfer belt in the image forming device, for example, and realize highly accurate belt conveyance control In addition, it is possible to provide an image forming apparatus that outputs a high-quality image with little color misregistration and positional deviation. In addition, the area sensor can be reduced in size and cost.

It is a block diagram of the moving member detection apparatus of one Embodiment of this invention. FIG. 5 is a configuration diagram in which the moving member of the embodiment is applied to a belt conveyance device of a multicolor image forming apparatus. It is a figure which shows the imaging lens and area sensor in Embodiment 2. It is a figure which shows the imaging lens and area sensor in Embodiment 3. FIG. 6 is a diagram illustrating a plurality of imaging lenses according to a fourth embodiment. 1 is a schematic configuration diagram showing an intermediate transfer type image forming apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus of a direct transfer system according to an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a moving member detection device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram in which the moving member according to the embodiment is applied to a belt conveyance device of a multicolor image forming apparatus. The moving member detection device 50 of this embodiment is provided in, for example, a belt conveyance device 100 incorporated in a later-described multicolor image forming apparatus. The belt conveyance device 100 detects the actual speed of the moving member E that is an intermediate transfer belt as a “conveyance belt” in an intermediate transfer type image forming apparatus. Further, in the direct transfer type image forming apparatus, the belt conveyance device 100 detects the actual speed of the moving member E that is a conveyance belt that conveys the recording medium to the transfer position.

  For example, as shown in FIG. 2, the belt conveyance device 100 conveys (rotates and moves) an endless belt-like moving member E stretched around the driving roller R1 and the plurality of driven rollers R2 and R3 in the clockwise direction in the drawing. The moving member detection device 50 of the embodiment and the motor 81 are included.

  As shown in FIG. 1, in the moving member detection device 50, the A position and the B position, which are two predetermined positions in the moving direction of the moving member E, are determined. Further, the moving member detection apparatus 50 includes a light source 51A that irradiates laser light as a “light beam” at the A position and a light source 51B that irradiates laser light as a “light beam” at the B position. Further, an image acquisition unit 52 that acquires image data from the detection position of the moving member E, and a speed calculation unit 53 that calculates the moving speed of the moving member E from the image data are provided.

  The image acquisition unit 52 includes the area sensor 11, an imaging lens 12 </ b> A disposed opposite to the A position, an imaging lens 12 </ b> B disposed opposite to the B position, the area sensor control unit 14, and the image storage unit 15. ing.

  The area sensor 11 is obtained by forming an image sensor 112 on a silicon substrate 111 that is a single substrate. On the image sensor 112, an A area 11A that is two image areas that can respectively acquire a two-dimensional image, B region 11B. As the area sensor 11, for example, a CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal-Oxide Semiconductor) sensor, a photodiode array, or the like can be used. The area sensor 11 is accommodated in the housing 13. The imaging lens 12A and the imaging lens 12B are held by lens barrels 13A and 13B, respectively. The optical axis of the imaging lens 12A coincides with the center of the area A 11A of the area sensor 11, and the optical axis of the imaging lens 12B coincides with the center of the area B 11B of the area sensor 11. The imaging lens 12A and the imaging lens 12B form a two-dimensional image in each of the A area 11A and the B area 11B.

  The area sensor control unit 14 includes a shutter control unit 141 and an image capturing unit 142. The shutter control unit 141 controls the shutter timing in the area sensor 11, the two-dimensional image formed on the image sensor 112 of the area sensor 11 is captured by the image capturing unit 142, and the captured image is an image. The data is output to the storage unit 15.

  The image storage unit 15 includes an image dividing unit 151, an A memory 152A, and a B memory 152B. The image from the image capturing unit 142 is divided by the image dividing unit 151 into A position image data D1 of the A area 11A and B position image data D2 of the B area 11B. The A position image data D1 is stored in the A memory 152A, and the B position image data D2 is stored in the B memory 152B. When the area sensor 11 is a CCD, the shutter timing in the area sensor 11 is a timing at which the shutter control unit 141 performs drive control of the vertical transfer CCD and the horizontal transfer CCD of the area sensor 11 and performs an operation of capturing an image. . This timing is determined by the data of the time difference Δt output from the speed calculation means 53 of the later operation, and the A position image data D1 at the A position and the B position image data D2 at the B position are taken in even with the time difference Δt.

  The speed calculation means 53 is composed of a microcomputer or the like, and calculates the actual speed of the moving member E based on the A position image data D1 and the B position image data D2 of the A memory 152A and the B memory 152B as will be described later. . Then, data of the time difference Δt for taking the shutter timing in the area sensor 11 is output to the shutter control unit 141. Further, the speed calculation means 53 outputs the calculated actual speed data to the controller 60 (FIG. 2) that controls the entire image forming apparatus, and the controller 60 controls the rotation of the motor 81.

  The light sources 51A and 51B include a light emitting element that emits laser light and a collimator lens that converts the laser beam emitted from the light emitting element into laser light that is substantially parallel light. The light sources 51A and 51B are arranged so as to irradiate the outer surface of the moving member E with laser light from an oblique direction.

  The moving member E is a belt-like member having scattering properties on the surface or inside thereof. Therefore, when the moving member E is irradiated with laser light, it is diffusely reflected as reflected light, and an image including speckles (speckle pattern) is obtained. This speckle pattern is formed by the interference of the laser beam corresponding to the uneven shape on the surface or inside of the moving member E. When the moving member E moves, the speckle pattern also maintains the pattern shape. Moving. This speckle serves as a virtual engraved mark on the moving member E to be detected, and the speed of the moving member E is detected by detecting the movement of the spec pattern as the engraved mark.

  In the present embodiment, the area sensor 11 uses a device that outputs two-dimensional image data, and the light receiving surface thereof is provided in parallel with the outer surface of the moving member E with an interval therebetween. The imaging lenses 12A and 12B are spaced apart from each other in the moving direction of the moving member E and are disposed to face the A position and the B position, respectively. Then, an image (that is, the speckle pattern) including the reflected light reflected by the moving member E is input via the imaging lenses 12A and 12B. When an area sensor that outputs one-dimensional image data is used, the longitudinal direction of the area sensor is arranged in parallel with the moving direction of the moving member E.

The speed calculation means 53 generates the time difference Δt, which is a difference in shutter timing in the area sensor 11 controlled by the shutter control unit 14a. Specifically, when the target speed of the moving member E is v [mm / s] and the relative distance between the optical axis of the imaging lens 12A at the A position and the optical axis of the imaging lens 12B at the B position is L [mm], the time difference Δt [s] is the following equation (1):
Δt = L / v (1)
Is calculated by

  The speed calculation unit 53 obtains the target speed v of the moving member E from, for example, the controller 60 that controls the entire image forming apparatus, and calculates the time difference Δt by dividing the target speed v by the relative distance L. To do. Then, the speed calculation unit 53 generates a time difference Δt and outputs it to the shutter control unit 14a.

  The image capturing unit 142 cooperates with the shutter control unit 141 to perform the A position image data D1 from the A region 11A corresponding to the A position of the area sensor 11 and the B position image from the B region 11B corresponding to the B position. Data D2 is periodically acquired. Specifically, the shutter control unit 141 controls the timing, and further controls the timing based on the time difference Δt input from the speed calculation means 53. By controlling the timing, the A position image data D1 is acquired in the A memory 152A at the time t0, and then the B position image data D2 is acquired in the B memory 152B at the time t0 + Δt by the time difference Δt. The A position image data D1 and the B position image data D2 are input to the speed calculation means 53.

The speed calculation means 53 detects the actual speed Vr of the moving member E based on the correlation image data obtained by performing the cross correlation calculation on the A position image data D1 and the B position image data D2. The cross-correlation calculation performed by the speed calculation means 53 is expressed by the following equation (2). Here, the A position image data is D1, the B position image data is D2, the Fourier transform is F [], the inverse Fourier transform is F ^-1 [], the complex conjugate is the symbol “*”, and the cross correlation operation is the symbol “★”. Then,
D1 * D2 ^* = F ⁻¹ [F [D1] · F [D2] ^* ] (2)
It becomes.

When cross-correlation calculation D1 * D2 ^* is performed on A position image data D1 and B position image data D2, correlation image data is obtained. Here, since the A position image data D1 and the B position image data D2 are two-dimensional image data, the correlation image data is also two-dimensional image data. If the A position image data D1 and the B position image data D2 are one-dimensional image data, the correlation image data is also one-dimensional image data.

Alternatively, when a broad luminance distribution becomes a problem in the correlation image data, phase-only correlation may be used. This phase only correlation is expressed by the following equation. Here, P [] indicates that only the phase is extracted from the complex amplitude (all amplitudes are set to 1).
D1 * D2 ^* = F ⁻¹ [P [F [D1]] · P [F [D2] ^* ]

  By using the phase-only correlation in this way, the positional deviation amount (correlation distance J) between the first partial data D1 and the second partial data D2 can be calculated with higher accuracy even in the case of a broad luminance distribution.

  This correlation image data indicates the correlation between the A position image data D1 and the B position image data D2. The higher the degree of coincidence between the A image indicated by the A position image data D1 and the B image indicated by the B position image data D2, the steeper peak (correlation peak) luminance appears at a position closer to the center position of the image indicated by the correlation image data. . When these A and B images match, the center position and peak position of the correlation image data overlap.

  In this embodiment, since the time difference Δt is set to a value obtained by dividing the target speed v of the moving member E by the relative distance L between the A position and the B position, the actual speed and the target speed v of the moving member E are set. If the two coincide with each other, the A image at the A position moves to the B position after the time difference Δt has elapsed. That is, the A image indicated by the A position image data D1 matches the B image indicated by the B position image data D2.

  That is, if the target speed v of the moving member E matches the actual speed, the center position and the peak position of the correlation image data overlap, and if the target speed v of the moving member E differs from the actual speed, those Depending on the difference, the center position and the peak position of the correlation image data are shifted. Therefore, in the correlation image data, the distance (correlation distance J) from the center position of the image indicated by the correlation image data to the steepest peak position is the speed deviation between the target speed v and the actual speed of the moving member E. ΔV is represented.

  Therefore, the speed deviation ΔV between the target speed v and the actual speed of the moving member E can be calculated by performing an operation for searching for the steepest peak in the correlation image data. In such a method using the cross-correlation calculation, the fast Fourier transform can be used, so that the speed deviation ΔV, that is, the actual speed of the moving member can be detected with a relatively small amount of calculation and high accuracy.

  As the area sensor 11, a camera using a CMOS sensor or a CCD sensor can be used. When the moving speed of the moving member E is fast, an image with little image shift can be acquired by using a sensor having a global shutter function.

In addition, although the imaging timing in the area sensor 11 is determined by the time difference Δt, the imaging timing here may be determined as appropriate depending on the required resolution. Also, the target speed is v, the speed error is dv, the relative distance is L, the position shift obtained by correlation calculation is dL, the time difference is Δt (s), the actual speed is the target speed v and the speed error dv is added. Then,
v + dv = (L + dL) / Δt
v = L / Δt
Since the deviation from the target speed is dv = dL / Δt
Is required. If feedback control is performed based on the obtained speed deviation, the belt conveyance speed can be controlled to be constant.

  As described above, it has been described that the actual speed of the moving member E can be accurately measured using the two imaging lenses 12A and 12B. If this configuration is used, even if the imaging magnification of the area sensors 12A and 12B changes due to environmental temperature changes, if the relative distance L does not change, the image position deviation is calculated as 0 when the speed is v. Therefore, it is not affected by the magnification change. In addition, when there is a speed error, dL is affected by a change in magnification, so dL includes a measurement error. However, if dv is small with respect to v, dL also becomes small, so the deviation is a very small value. become. For example, when dv is generated about 1% with respect to v, even if a magnification change occurs by 1% due to temperature change, the measurement error for v is 0.01 × 0.01 = 0.0001 (0. (01%). As described above, if speed measurement using image correlation is performed using the present invention, highly accurate speed measurement is easily realized, and a highly accurate belt speed conveying apparatus can be provided.

  In the above-described embodiment, the actual speed of the moving member E is determined based on the correlation image data obtained by performing the cross-correlation calculation using Fourier transform on the A position image data D1 and the B position image data D2. However, the present invention is not limited to this. For example, the luminance included in the A position image data D1 and the B position image data D2 is binarized as “0” when the luminance is equal to or lower than a predetermined threshold, and as “1” when the luminance is higher than the threshold. To do. Then, the correlation distance J may be obtained by directly comparing the A position image data D1 and the B position image data D2. As described above, the method of detecting the actual speed of the moving member E based on the A position image data D1 and the B position image data D2 is arbitrary as long as the object of the present invention is not violated.

  As described above, if speed measurement using image correlation is performed, highly accurate speed measurement is easily realized, and a highly accurate belt speed conveying apparatus can be provided. In addition, since the image pickup system including the plurality of image pickup lenses 12A and 12B is held in one area sensor 11, for example, the detection accuracy of the surface speed of the intermediate transfer belt in the image forming apparatus can be improved. Therefore, it is possible to provide an image forming apparatus that realizes high-accuracy belt conveyance control and outputs a high-quality image with little color misregistration and positional deviation. In addition, the area sensor can be reduced in size and cost.

  In the first embodiment described above, an example in which the two imaging lenses 12A and 12B are held by the two lens barrels 13A and 13B has been described, but the following second and third embodiments are described. You may make it like Embodiment 4. FIG. 3 is a diagram illustrating the imaging lenses 12A and 12B and the area sensor 11 according to the second embodiment. The area sensor 11 is the same as that of the first embodiment. In this example, a lens element 120 in which two imaging lenses 12A and 12B are integrated is used as an imaging lens. Here, the image forming area is limited by using the aperture 121 so that images from the respective imaging lenses 12A and 12B do not form an image by interfering with the corresponding A area 11A and B area 11B. . By doing in this way, the image of each position can be taken in, without the images imaged with imaging lens 12A, 12B interfering with each other.

  FIG. 4 is a diagram illustrating the imaging lenses 12A and 12B and the area sensor 11 ′ according to the third embodiment. The imaging lenses 12A and 12B are the same as in the second embodiment. As shown in FIG. 4B, the area sensor 11 'forms a plurality of imaging elements b, b,... On a single wafer a at a time, and cuts out from the wafer a to form one silicon substrate. 111 includes a plurality of imaging elements 112A and 112B. The positions of the two imaging lenses 12A and 12B are determined in accordance with the interval between the plurality of imaging elements 112A and 112B on one silicon substrate 111.

  In general, since an image sensor is created for image recording, a device having a ratio in the xy direction, that is, an aspect ratio that matches the image format such as square, 4: 3, or 16: 9 is produced. Yes. In this embodiment, since it is desired to record two or more images that are separated by a certain distance, it is desired to record images with a distance in the two-dimensional one-dimensional direction (only the x direction (movement direction) in the xy direction). When one image sensor is used, there are many elements having the same length in the xy direction as described above. For this reason, for example, when it is desired to take a certain distance in the x direction, there is a problem that the element in the y direction is wasted. Also, when it is desired to increase the pixel density, it is necessary to use elements with high density in both directions of xy, leading to an increase in cost.

  However, in this embodiment, by using the area sensor 11 ′ in which a plurality of image sensors b, b,... Created on the wafer a are simultaneously cut out, the image sensors 112A and 112B having a constant interval are automatically used. It can be obtained. In this way, by forming an image on each element having a plurality of imaging elements 112A and 112B with a plurality of imaging lenses 12A and 12B, the imaging device can be effectively used without waste, and a high accuracy created by a semiconductor process. Accurate position interval can be obtained. Therefore, the image sensors 112A and 112B can be used without waste to reduce the cost and increase the speed accuracy.

  FIG. 5 is a diagram illustrating a plurality of imaging lenses according to the fourth embodiment. In this embodiment, a lens array in which two or more lenses are integrated is used as an imaging lens. In the above-described embodiment, the method of measuring the speed by the position change between the two positions A and B has been described, but the configuration shown in FIG. 5 may be used. If two or more lens array devices 120 ′ having nine image pickup lenses 12A1 to 12C3 in a total of three rows and three columns, for example, nine image data can be captured at a time. Of course, an area sensor having an imaging area corresponding to each of the imaging lenses 12A1 to 12C3 is used. In this way, two imaging lenses in which the arrangement direction of the two imaging lenses is the row direction, the direction intersecting the row direction is the column direction, and four or more lenses arranged in a matrix in the row direction and the column direction are integrated. A lens array device including a lens is used. By doing so, for example, operations in two areas can be executed simultaneously at a plurality of locations, and the results are averaged or compared with operations at one location by eliminating operation errors. Accuracy and stability can be improved. In addition, since an area where correlation calculation can be performed is widened even in an application (processing software) in which the speed fluctuates, a highly accurate speed calculation result can be obtained.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 shows a basic configuration example of a multicolor image forming apparatus 200 according to an embodiment of the present invention. Reference numerals 1Y, 1M, 1C, and 1K in the drawing are drum-shaped photoconductors arranged side by side along the intermediate transfer belt 105 as the moving member E. Each photoconductor 1Y, 1M, 1C, 1K is rotated in the direction of the arrow in the figure, and around it is a charger 2Y, 2M, 2C, 2K, each color developing device 4Y, 4M, 4C, 4K, primary transfer means 6Y. , 6M, 6C, 6K, and photoconductor cleaning means 5Y, 5M, 5C, 5K, and the like. In the drawing, reference numeral 30 denotes a fixing unit, 40 denotes a secondary transfer unit, and 41 denotes a conveying unit.

  The image forming apparatus 200 is an intermediate transfer belt type multi-color image forming apparatus, and includes a belt conveyance device 100 that conveys the intermediate transfer belt 105. In this belt conveying apparatus 100, an intermediate transfer belt 105 as a moving member E is stretched around a driving roller R1, driven rollers R2, R3, and R4, and a motor 81 is connected to the intermediate transfer belt 105 (driving roller R1). Is rotated counterclockwise (moving direction) in the figure. Further, the moving member detection device 50 described above detects actual speed information such as the speed deviation ΔV and the actual speed Vr regarding the intermediate transfer belt 105. A motor control unit (not shown) controls the motor 81 based on the actual speed information so that the intermediate transfer belt 105 rotates at the target speed Vt.

  Each of the photoreceptors 1Y, 1M, 1C, and 1K is uniformly charged by the chargers 2Y, 2M, 2C, and 2K, and then the light beam whose intensity is modulated according to the image information is exposed by the optical scanning device 20, and is electrostatically charged. A latent image is formed. The electrostatic latent images formed on the photosensitive drums 1Y, 1M, 1C, and 1K are developed by the yellow developing device 4Y, the magenta developing device 4M, the cyan developing device 4C, and the black developing device 4K. That is, the toner image is visualized as a toner image of each color of yellow, magenta, cyan, and black.

  The toner images on the photoconductors 1Y, 1M, 1C, and 1K that have been visualized in the above-described developing process are sequentially superimposed on the intermediate transfer belt 105 and primarily transferred. Then, the toner images of the respective colors superimposed on the intermediate transfer belt 105 are fed from a paper feeding unit (not shown), and are recorded on paper or the like that is conveyed to the position of the secondary transfer unit 40 via a conveyance unit (not shown). Secondary transfer is performed collectively on the medium. Then, the recording medium on which the toner image is transferred is conveyed to the fixing unit 30 by a conveying unit 41 such as a conveying belt, and the toner image is fixed on the recording medium by the fixing unit 30 to obtain a multicolor image or a full color image. . Then, the fixed recording medium is discharged to a discharge unit (not shown), a post-processing device, or the like.

  Further, the photoreceptors 1Y, 1M, 1C, and 1K after the toner image transfer are cleaned by cleaning members (blades, brushes, and the like) of the cleaning units 5Y, 5M, 5C, and 5K, and residual toner is removed. Further, the intermediate transfer belt 105 after the toner image transfer is also cleaned by a belt cleaning unit (not shown) to remove residual toner.

  In the image forming apparatus 200 shown in FIG. 6, a single color mode for forming an image of any one color of yellow, magenta, cyan, and black, and an image of any two colors of yellow, magenta, cyan, and black are formed in an overlapping manner. Have two color modes. In addition, there is a three-color mode in which images of three colors of yellow, magenta, cyan, and black are superimposed and a full-color mode in which a superimposed image of four colors is formed as described above. By specifying and executing these modes with an operation unit (not shown), it is possible to form a single color, a multicolor, or a full color image.

  A multicolor image forming apparatus 200A configured as shown in FIG. 7 may be used. That is, instead of the intermediate transfer belt, a transfer belt 106 as a moving member E for carrying and transferring a recording medium such as paper is used, and the photosensitive drums 1Y, 1M, 1C, and 1K are directly transferred to a recording medium such as paper. A multi-color image forming apparatus may be used. In this direct transfer type image forming apparatus 200A, as shown in FIG. 7, the approach path of a recording medium such as paper is different from that in FIG. A recording medium is conveyed toward the photosensitive drums 1Y, 1M, 1C, and 1K by the conveyance belt 106.

  Further, the image forming apparatus 200 </ b> A includes a belt conveyance device 100 that conveys the conveyance belt 106. In the belt conveying apparatus 100, a conveying belt 106 as a moving member E is stretched around a driving roller R1 and a driven roller R2, and a motor 81 rotates the conveying belt 106 (driving roller R1) counterclockwise in the drawing. It is driven to rotate in the (movement direction). Further, the moving member detection device 50 described above detects actual speed information such as the speed deviation ΔV and the actual speed Vr regarding the conveyor belt 106. A motor control unit (not shown) controls the motor 81 based on the actual speed information so that the intermediate transfer belt 105 rotates at the target speed Vt.

  In the image forming apparatus 200A shown in FIG. 7 as well, each of the photoconductors 1Y, 1M, 1C, and 1K is uniformly charged by the chargers 2Y, 2M, 2C, and 2K, and then converted into image information by the optical scanning device 20. In response, the light beam whose intensity is modulated is exposed to form an electrostatic latent image. The electrostatic latent images formed on the photosensitive drums 1Y, 1M, 1C, and 1K are developed by the yellow developing device 4Y, the magenta developing device 4M, the cyan developing device 4C, and the black developing device 4K. That is, the toner image is visualized as a toner image of each color of yellow, magenta, cyan, and black.

  Then, a recording medium such as paper is fed from a paper feeding unit (not shown) at the same timing as the developing process, and is conveyed to the conveyance belt 106 through a conveyance unit (not shown) and is carried on the conveyance belt 106. The recording medium carried on the conveyance belt 106 is conveyed toward the respective photosensitive drums 1Y, 1M, 1C, and 1K, and the toner on each of the photosensitive bodies 1Y, 1M, 1C, and 1K that has been visualized in the above development process. The images are sequentially transferred onto the recording medium by transfer means 6Y, 6M, 6C, and 6K. Then, the four-color superimposed toner image transferred onto the recording medium is conveyed to the fixing unit 30, and the fixing unit 30 fixes the toner image on the recording medium, thereby obtaining a multicolor or full-color image. Then, the fixed recording medium is discharged to a discharge unit (not shown), a post-processing device, or the like.

  Further, the photoreceptors 1Y, 1M, 1C, and 1K after the toner image transfer are cleaned by cleaning members (blades, brushes, and the like) of the cleaning units 5Y, 5M, 5C, and 5K, and residual toner is removed.

  As described above, since the image forming apparatuses 200 and 200A include the belt conveyance device 100 described above, the moving member detection device 50 of the belt conveyance device 100 causes the intermediate transfer belt 105 or the conveyance belt 106 to be used. The speed Vr can be calculated in a short time, and the actual speed Vr can be detected with high accuracy. For this reason, by feeding back information such as the actual speed Vr to the motor 81, the belt speed fluctuation becomes substantially zero. As a result, it is possible to provide a high-quality color image in which the expansion and contraction of the image and the color shift are suppressed to be small. Further, with respect to the belt-like member and the roller-like member used as the fixing device, it is also possible to detect and correct the speed fluctuation using the moving member detecting device 50 described above.

  Further, a writing start position correcting unit (for example, a liquid crystal deflecting element provided in the optical scanning device 20) for correcting the writing start position by the optical scanning device 20 based on the detection result of the speed fluctuation of the intermediate transfer belt or the conveyance belt. It is also possible to provide feedback. The liquid crystal deflecting element can shift the position of light reaching the photoconductor in a direction parallel to the rotation direction of the photoconductor by a voltage applied to the liquid crystal. When the belt speed fluctuation occurs, the superposition of each color image shifts, or each color image itself expands or contracts. By using a liquid crystal deflecting element, the color toner image of each color image is corrected in the same manner as the correction of the belt speed fluctuation. Since the formation position and the expansion / contraction of the image can be corrected, it is possible to obtain a high-quality output image with no color shift or image expansion / contraction as a result.

  The above-described embodiment has been described with respect to an image forming apparatus. However, the present invention is not limited to this, and a device that detects the speed of a conveyor belt and a speed detection of a moving member that moves in one direction. The present invention can be applied to any apparatus, system, etc. that require the above.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

11, 11 'area sensor 11A A area (imaging area)
11B B area (imaging area)
111 Silicon substrate (substrate)
112 imaging device 112A, 112B imaging device 12A, 12B imaging lens 12A1, 12B1, 12C1 imaging lens 12A2, 12B2, 12C2 imaging lens 12A3, 12B3, 12C3 imaging lens 51A, 51B light source 52 image acquisition means 53 speed calculation means 14 area sensor control Means 141 Shutter control unit 142 Image reading unit 15 Image storage unit 151 Image division unit 152A A memory 152B B memory E Moving member

Japanese Patent No. 4545580 JP 2009-15240 A JP 2010-55064 A

Claims (6)

A light source that irradiates the detection position of the moving member with a light beam; image acquisition means for acquiring image data from the detection position of the moving member; and speed calculation means for calculating the moving speed of the moving member from the image data. A moving member detecting device comprising:
The image acquisition means is disposed opposite to an area sensor having at least two imaging areas on an imaging element formed on one substrate, and A position and B position which are two positions in the moving direction of the moving member. Two imaging lenses that respectively form images in the imaging region of the area sensor, and area sensor control means for acquiring image data by the area sensor at a set timing,
The image acquisition means acquires B position image data at the B position when the moving member moves to the B position after acquiring the A position image data at the A position.
The moving member detecting device, wherein the speed calculating means calculates a moving speed of the moving member from the A position image data and the B position image data.   The moving member detection apparatus according to claim 1, wherein the two imaging lenses arranged to face the A position and the B position are configured by a lens element in which two or more lenses are integrated.   The area sensor is configured to include a plurality of image pickup devices on the one substrate by cutting out from the wafer in which a plurality of image pickup devices are formed on one wafer at a time. The moving member detection device according to claim 1, wherein the position is determined in accordance with the interval between the plurality of image pickup devices on the one substrate.   The two imaging lenses in which the arrangement direction of the two imaging lenses is a row direction, the direction intersecting the row direction is a column direction, and four or more lenses arranged in a matrix in the row direction and the column direction are integrated. The moving member detection apparatus according to any one of claims 1 to 3, wherein a lens array including the lens array is used.   The belt conveyance device comprising the movement member detection device according to any one of claims 1 to 4, wherein the movement member is a conveyance belt.   An image forming apparatus comprising the belt conveyance device according to claim 5, wherein the belt is an intermediate transfer belt or a conveyance belt.

Images