JP2020058012A - Reading device and image forming apparatus - Google Patents

Abstract

To accurately read an edge position of an object.SOLUTION: A reading device detects an edge position in a width direction of an object to be conveyed, the width direction being a direction intersecting a conveyance direction. The reading device comprises: a sensor unit that has a pixel array in which a plurality of pixels outputting a detection signal are arranged in a width direction, and is arranged such that the same can read an edge position; an addition unit that adds output signals from the pixels in the pixel array at every position in the width direction; and an edge position detection unit that detects the edge position in the width direction of the object on the basis of a position at which an output from the addition unit changes to a value larger than a first predetermined threshold. The plurality of pixels output detection signals according to the amount of received light in wavelength ranges different from each other.SELECTED DRAWING: Figure 27

Description

  The present invention relates to a reading device and an image forming device.

  The image forming apparatus according to Patent Literature 1 sequentially turns on a plurality of light sources having different wavelengths, turns on the light sources, and detects the end position of the sheet in the width direction using reflected light from the sheet that matches the color of the sheet. Then, the end position of the transfer paper is detected with high accuracy.

  The image forming apparatus disclosed in Japanese Patent Application Laid-Open No. H11-157572 discloses reading image data obtained by reading an opposing member when a document sheet is not conveyed to a reading position in order to determine whether dust or the like is attached to the opposing surface of the document pressing member. Is calculated, and this is compared with the reference edge pixel number. If the calculated number of edge pixels and the number of reference edge pixels do not match within the specified number, the process shifts to a cleaning mode for cleaning the opposing surface of the document pressing member.

  The present invention has been made in view of the above points, and has as its object to accurately read an edge position of an object.

  A reading device that detects an edge position in a width direction that is a direction intersecting with a conveyance direction of an object to be conveyed, comprising a pixel array in which a plurality of pixels that output a detection signal are arranged in the width direction. A sensor unit arranged so as to be able to read the edge position, an addition unit for adding an output signal of the pixel of the pixel array for each position in the width direction, and an output of the addition unit being a first predetermined An edge position detection unit that detects an edge position in the width direction of the object based on a position that changes to a value greater than a threshold value, wherein the plurality of pixels each correspond to a light reception amount of light in a different wavelength band. The reading device outputs the detected signal.

  According to the present invention, the edge position of an object can be accurately read.

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus having an edge position reading device according to a first embodiment. FIG. 3 is a diagram illustrating a configuration of a sensor unit in the edge position reading device according to the first embodiment. FIG. 3 is a diagram illustrating a positional relationship between a sensor unit and a sheet in the edge position reading device according to the first embodiment. FIG. 2 is a block diagram illustrating a hardware configuration of the edge position reading device according to the first embodiment. FIG. 2 is a block diagram illustrating a functional configuration of a control device in the edge position reading device according to the first embodiment. 5 is a flowchart illustrating a process of a control device in the edge position reading device according to the first embodiment. FIG. 9 is a diagram illustrating a first example of data read by a conventional edge position reading device. FIG. 9 is a diagram illustrating a second example of data read by a conventional edge position reading device. FIG. 11 is a diagram illustrating a third example of data read by a conventional edge position reading device. FIG. 3 is a diagram illustrating data read by the edge position reading device according to the first embodiment. FIG. 4 is a diagram illustrating the influence of reflected light in a background area in the edge position reading device. FIG. 9 is a diagram illustrating a state of reading an edge position by the edge position reading device according to the second embodiment. FIG. 11 is a diagram illustrating how an edge position reading device according to a third embodiment reads an edge position. FIG. 14 is a diagram illustrating how an edge position reading device according to a fourth embodiment reads an edge position. FIG. 3 is a diagram illustrating the inclination of a sheet being conveyed. It is a figure which illustrates the data read by the edge position reading device of a 5th embodiment. It is a block diagram which illustrates the functional composition of the control device in the edge position reading device of a 5th embodiment. FIG. 16 is a diagram illustrating an example of correction of a position and a tilt of a sheet based on an output of the edge position reading device according to the fifth embodiment. It is a block diagram which illustrates the functional composition of the control device in the edge position reading device of a 6th embodiment. It is a figure showing the 1st example of the data read by the edge position reading device of a 6th embodiment. It is a figure showing the 2nd example of the data read by the edge position reading device of a 6th embodiment. FIG. 4 is a diagram illustrating an example of instability of an output value of a pixel due to a type of paper. It is a block diagram which illustrates the functional composition of the control device in the edge position reading device of a 7th embodiment. FIG. 9 is a diagram illustrating an example of an effect of a width direction moving average process. FIG. 9 is a diagram illustrating an example of a side effect of the width direction moving average processing. It is a block diagram which illustrates the functional composition of the control device in the edge position reading device of an 8th embodiment. It is a block diagram which illustrates the functional composition of the control device in the edge position reading device of a 9th embodiment. FIG. 7 is an explanatory diagram of the amount of reflected light during edge detection processing and foreign matter detection processing. It is a block diagram which illustrates the functional composition of the control device in the edge position reading device of a 10th embodiment. FIG. 9 is an explanatory diagram of threshold values at the time of edge detection processing and foreign matter detection processing. It is a flowchart which shows the 1st example of a foreign substance detection process. FIG. 4 is a diagram illustrating an area read by a sensor unit. It is a block diagram which illustrates the functional composition of the control device in the edge position reading device of an eleventh embodiment. It is an example of reading conditions at the time of edge detection processing. It is a flowchart which shows the 2nd example of a foreign material detection process. 13 is a flowchart illustrating an example of an edge detection process. FIG. 9 is a diagram illustrating another configuration of the image forming apparatus having the edge position reading device.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

[First Embodiment]
FIG. 1 is a cross-sectional view illustrating the configuration of an image forming apparatus 500 having the edge position reading device 100 according to the first embodiment.

  An automatic document feeder 1 having a document table 2 is provided above the image forming apparatus 500. When the print key is pressed, the document bundle placed on the document table 2 is fed to a predetermined position on the contact glass 5 by the feeding roller 3 and the feeding belt 4 in order from the bottom document. .

  The scanner unit 6 optically reads a document fed onto the contact glass 5 and acquires image data. The writing unit 7 irradiates the surface of the photoconductor 8 with a laser beam based on the image data acquired by the scanner unit 6 to form an electrostatic latent image. The electrostatic latent image formed on the surface of the photoconductor 8 is formed into a toner image by the developing unit 9.

  The paper P stored in the paper trays 11, 12, and 13 is fed by paper feeding devices 14, 15, and 16, respectively, and is transported by the transport unit 10. The toner image formed on the surface of the photoconductor 8 is transferred to the paper P at a transfer position 22 which is an example of an image forming unit between the photoconductor 8 and the transfer unit 17. The sheet P to which the toner image has been transferred is conveyed to the fixing unit 18 and is heated and pressed to fix the toner image on the surface. The sheet P that has passed through the fixing unit 18 is discharged outside the apparatus by a sheet discharging unit 19.

  In the case of performing double-sided printing, the paper P that has passed through the fixing unit 18 is stocked in the double-sided paper feeding / conveying unit 21 by switching the conveying path by the branching claws 20. The sheet P stocked in the double-sided sheet feeding / conveying unit 21 is turned over, conveyed again toward the photoconductor 8, and discharged outside the apparatus after a toner image is formed on the back surface.

  The image forming equipment 500 further has an operation panel 23. The operation panel 23 receives various inputs according to the operation of the user, and displays various information (for example, information indicating the received operation, information indicating the operation status of the image forming apparatus 1, and the setting state of the image forming apparatus 1). Etc.). That is, the operation panel 23 is an example of an input receiving unit and an example of a display unit. The operation panel 23 includes a liquid crystal display (LCD) having a touch panel function, but is not limited to this. For example, it may be configured by an organic EL (Electro-Luminescence) display device equipped with a touch panel function. Further, in addition to or instead of this, input can be accepted with a hardware key, or information can be displayed with a lamp or the like. The above-mentioned print key is provided on the operation panel 23 as an example. Although FIG. 1 is a cross-sectional view of the image forming apparatus 500, the operation panel 23 is shown in a state of being exposed outside the image forming apparatus 500 so that a user can operate the operation panel 23. I do.

  The image forming apparatus 500 includes a sheet edge position reading device 100 on a sheet P conveyance path. The edge position reading device 100 reads the edge position of the paper P being conveyed, and grasps the conveyance position of the paper P. By adjusting the image forming position according to the transport position of the sheet P, the image position shift on the sheet P is prevented.

  Next, an example of a configuration of the sensor unit 210 included in the sheet edge position reading device 100 according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram schematically illustrating the configuration of the sensor unit 210. (A) is a side view, and (b) is a plan view. In FIG. 2, thick black arrows indicate the transport direction of the paper P, and thick white arrows indicate the direction crossing the transport direction of the paper P, that is, the width direction. The width direction is a typical example of the “predetermined direction”.

  The sensor unit 210 has a light source unit 211 and a light receiving unit 212.

  The light source unit 211 irradiates one end in the width direction of the conveyed sheet P, that is, a region through which the edge passes, with linear light that is long in the width direction. The light source unit 211 has an LED (Light Emitting Diode) array 211d and a substrate 211a. A plurality of LEDs that emit light having a wide wavelength band close to white light are arranged in the width direction on the substrate 211a.

  However, the light source unit 211 is not limited to the above configuration, and simultaneously illuminates red, green, and blue LEDs, mixes the light of each color, and emits light having a wide wavelength band close to white light. May be. Further, for example, a configuration including one element that irradiates long linear light in the width direction, such as a fluorescent tube, may be employed. According to the fluorescent tube, white light with uniform brightness in the width direction can be emitted.

  Furthermore, by using a light guide member having the width direction as the longitudinal direction, the white or red, green, and blue LEDs arranged at both ends of the light guide member are turned on, and the light is passed through the light guide member. Irradiated light may be applied. The light guide member can irradiate light with uniform brightness in the width direction. In addition to these, as long as linear light can be emitted in the width direction, the light source unit 211 may have a configuration different from the above-described example. Further, a configuration may be adopted in which a light guide lens for efficiently guiding the light from the LED array 211d to a region where the edge in the width direction of the conveyed paper P passes is provided.

  The light receiving section 212 includes a substrate 212a, a pixel array 212r that receives red light, a pixel array 212g that receives green light, and a pixel array 212b that receives blue light.

  The pixel array is a photoelectric conversion element that converts an optical signal into an electric signal, for example, an element in which PDs (Photo Diodes) are arranged in an array in the width direction. One photoelectric conversion element corresponds to one pixel and outputs an electric signal according to the amount of light received. The “electric signal according to the amount of light received” is a typical example of a detection signal. The pixel array outputs electric signals of pixels for one line.

  As illustrated, each of the pixel array 212r, the pixel array 212g, and the pixel array 212b is arranged in the transport direction with the width direction and the pixel arrangement direction being substantially parallel.

  The pixel array 212r that receives the red light has a red color filter in front of the light receiving surface, and receives the red light that has passed through the color filter. The red color filter transmits light in the red wavelength band and absorbs or reflects light in other wavelength bands. Similarly, the pixel arrays 212g and 212b have green and blue color filters, respectively, and receive light in the green and blue wavelength bands. A color filter that transmits red, green, or blue light is a typical example of “red, green, or blue color selecting means”.

  Note that a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) may be used for the pixel array. In addition, the light receiving unit 212 may be configured using a CCD or CMOS area sensor having a two-dimensional pixel array. Furthermore, a lens array such as a rod lens array for guiding the light reflected by the paper P to the pixel array may be provided in order to increase the light collection efficiency of the light receiving unit 212.

  The sensor unit 210 irradiates light near the linear white light from the light source unit 211 to a region where the edge in the width direction of the paper P passes. Then, the light receiving section 212 receives the reflected light from the area through which the edge in the width direction of the paper P passes. Of the reflected light, red light is received by the pixel array 212r, green light is received by the pixel array 212g, and blue light is received by the pixel array 212b.

  When irradiating only monochromatic light and receiving reflected light, depending on the color of the paper P, the irradiated light may be absorbed by the paper P and sufficient reflected light may not be obtained. By irradiating light close to white light and receiving red, green, and blue light as in the present embodiment, it is possible to read the edge position compared to the case where only monochromatic light is used. The colors and types of the paper P can be increased.

However, the configuration for obtaining such an effect is not limited to the above. For example, a configuration in which three LED arrays of red, green, and blue are used as light sources, and light of each color is received in a time-sharing manner by one pixel array while each LED array is sequentially turned on. With this configuration,
The colors and types of the paper P can be increased in the same manner as described above.

  Further, the sensor unit 210 may be configured by a CIS (Contact Image Sensor). The CIS is an image sensor that integrates a light receiving unit, a light source unit, and a rod lens array (actual magnification imaging lens). By using the CIS, for example, it is possible to obtain an effect that the edge position can be compactly read by approaching the surface of the sheet.

  FIG. 3 illustrates an example of a positional relationship between the sensor unit 210 and the sheet P in the edge position reading device 100. In FIG. 3, the paper P is being transported in the direction of the thick black arrow. The sensor unit 210 is provided so as to straddle one end of the sheet P, that is, the edge, in the width direction indicated by the white arrow. The position in the width direction of the edge of the sheet P straddled by the sensor unit 210 is read by the sensor unit 210. “The sensor unit 210 provided so as to straddle one end of the sheet P, that is, the edge in the width direction” is a typical example of “the sensor unit arranged so as to be able to read the edge of the object”.

  Next, the hardware configuration of the edge position reading device 100 will be described with reference to the block diagram of FIG. The edge position reading device 100 has a sensor unit 210 and a control device 300. The edge position reading device 100 operates according to a command from the control device 300.

  The sensor unit 210 includes a light source unit 211, a light receiving unit 212, and an AFE (Analog Front End) 213. The AFE 213 is an analog circuit that connects a signal detection device such as a sensor and a digital signal processing device such as a microcomputer and an electronic hardware circuit. The AFE 213 outputs a drive signal to the light receiving unit 212 and the light source unit 211 at a predetermined timing according to a command from the control device 300.

  The light source 211 turns on or off when a drive signal is input from the AFE 213. Lighting emits linear light that is long in the width direction at a predetermined light amount.

  When the drive signal is input from the AFE 213, the light receiving unit 212 outputs to the AFE 213 an analog voltage signal for one line that is long in the width direction, in which the received light is photoelectrically converted by each pixel of the pixel array. When an analog voltage signal is input from a pixel array included in the light receiving unit 212, the AFE 213 performs A / D (Analog / Digital) conversion and outputs a digital voltage signal of each pixel to the control device 300.

  When a signal is input from the AFE 213, the control device 300 executes a process of adding pixel output values, a process of detecting an edge position, and the like, as described later, and reads an edge position of the conveyed sheet P. The reading result is output to the correction device 400 connected to a subsequent process of the control device 300. The correction device 400 is a device that appropriately positions the sheet P and an image formed on the sheet P in accordance with the output of the edge position reading device 100. The writing device 6 is an example of the correction device 400. In this case, the writing device 6 that is the correction device 400 that has output the read result adjusts the image forming position of the image of the sheet P to be conveyed next according to the edge position that is the read result. The correction device 400 is not limited to the writing device 6, and may be a paper position correction device or the like that corrects the position of the paper P before reaching the image forming position 22. Although the configuration using the AFE 213 has been described above, the processing performed by the AFE 213 may be performed by an LED driver circuit, a pixel array driver circuit, an A / D converter, or a combination thereof.

  The control device 300 is configured by, for example, an FPGA (Field-Programmable Gate Array). However, part or all of the processing performed by the FPGA may be executed by a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or the like. Further, the control device 300 may be configured to have a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory). For example, control of the light source unit 211 and processing of output of pixels read by the light receiving unit 212 are performed using a RAM as a work memory according to a program stored in the ROM in advance. Further, the control device 300 may include a non-volatile storage medium for storing setting values used for control by the control device 300, for example, an HDD (Hard Disc Drive) or the like.

  Further, the configuration in which the control device 300 is provided outside the sensor unit 210 has been described, but the configuration is not limited to this. The sensor unit 210 may have a configuration including the control device 300, or the image forming apparatus or the correction device 400 in a later process may have a configuration including the control device 300.

  Further, the configuration in which the sensor unit 210 includes the AFE 213 has been described. However, a configuration in which the AFE 213 is provided outside the sensor unit 210 may be employed, or a correction device or the like in a later process may include the AFE 213.

  The control device 300 can realize the functional configuration described below with the above hardware configuration.

  FIG. 5 is a block diagram illustrating an example of a functional configuration of the control device 300. The control device 300 includes a communication unit 301, a drive clock generation unit 302, and a pre-processing unit 303. Further, the control device 300 includes a condition setting unit 304, a signal level detection unit 305, a signal output addition processing unit 306, and an edge position detection unit 307.

  The communication unit 301 performs communication to control devices connected to the control device 300, such as the AFE 213 and the correction device, and to input and output data. As a communication method, for example, serial communication is used.

  The drive clock generation unit 302 generates a drive clock signal and outputs it to the AFE 213 via the communication unit 301. At a timing based on the generated drive clock signal, the light source unit 211 and the light receiving unit 212 in the sensor unit 210 are controlled via the AFE 213.

  The preprocessing unit 303 performs a process for removing output noise and the like as preprocessing of the process of the pixel output read by the sensor unit 210. The pre-processing includes, for example, a moving average processing in the width direction and an average processing in the transport direction.

  The width direction moving averaging process is a process of averaging output values of pixels adjacent in the width direction in the pixel array of the light receiving unit 212 while shifting the section. For example, at a pixel at an arbitrary position in the width direction, an average value of output values of seven adjacent pixels is obtained, and is set as an output value of the pixel. By this processing, output noise due to dust attached to the light receiving surface, shot noise or thermal noise for each pixel, or the like is removed or reduced. When a rod lens is used, output noise having reproducibility may occur, for example, having a periodicity such as an interval of seven pixels. Since the light collected by the rod lens has an intensity distribution, the intensity distribution is generated by overlapping the intensity distribution of each rod lens with the arrangement of the rod lenses. Such noise is also removed or reduced by the widthwise moving average processing.

  The transport direction averaging process is a process for averaging the output values of the pixels in the transport direction, that is, the direction crossing the width direction. When the output value of each pixel greatly varies in the width direction, output noise of the pixel is removed or reduced by averaging the output values of the pixels even in the direction crossing the width direction. For example, when a plurality of pixel arrays are provided in the transport direction, the average value of the output values of the pixels adjacent in the transport direction at the arbitrary position in the width direction is determined as the output value of the pixel. When a plurality of pixel arrays are not provided in the transport direction, a plurality of output values are obtained in a time-division manner at pixels at an arbitrary position in the width direction while transporting the sheet P, and an average value of these is obtained. The output value of the pixel is used.

  Note that the content of the pre-processing is not limited to the above, and can be variously changed according to the situation of noise or the like.

  The condition setting unit 304 sets conditions for reading the edge position. For example, in the width direction moving average processing, preprocessing conditions such as the number of adjacent pixels for averaging output values are set. Further, reading conditions such as the number of times the edge of the sheet P is read, the edge reading position and timing in the transport direction, and a threshold value for detecting the edge position and an edge detection condition such as a method of determining the threshold value are set. The input of conditions can be performed, for example, by reading a condition file in which setting data of various conditions is recorded from an external storage device such as a USB (Universal Serial Bus) via the communication unit 301. The various conditions to be set may be those previously stored in a storage medium such as an HDD of the image forming apparatus 500.

  The signal level detection unit 305 acquires the signal levels Vh and Vl of the output value of the pixel. The signal levels Vh and Vl in the present embodiment are, for example, the maximum value and the minimum value among the output values of the pixels for one line of the pixel array arranged in the width direction. The acquired signal levels Vh and Vl are used for calculating the threshold when automatically determining the threshold. However, the signal levels Vh and Vl are not limited to the maximum value and the minimum value as described above. For example, in the pixel array, the output value of the reflected light is obtained by using the pixel that can obtain the output value of the reflected light from the sheet even if the sheet P is the smallest size among the conveyed sheets P. The signal level Vh may be calculated based on the obtained output value. When the acquired signal level Vh is equal to or less than a predetermined threshold, a predetermined value, that is, a fixed value may be set as the signal level Vh. From the obtained Vh, a threshold may be determined as Vh / 2.

  On the other hand, as the signal level Vl, a predetermined value determined in advance, that is, a fixed value may be used without acquiring data. Since the signal level Vh varies greatly depending on the paper P being conveyed, it is necessary to obtain the signal level Vh from the acquired data. However, since the signal level Vl is the output value of the background area, the output value does not vary much.

  The signal output addition processing unit 306 adds the output values of the pixels of the pixel array for each position in the width direction. Specifically, for example, at an arbitrary position in the width direction, the pixel output value for the red light by the pixel array 212r, the pixel output value for the green light by the pixel array 212g, and the pixel output value for the blue light by the pixel array 212b. The output value of the pixel is added. Then, the added value is output as the output value of the pixel at that position.

  Note that the output of each pixel of the pixel array is a signal, and the output value slightly changes with time. The “output value of a pixel that changes with time” is an example of the “output signal of a pixel”. Further, the signal output addition processing unit 306 is an example of “an addition unit that adds output signals of pixels of the pixel array for each position in the predetermined direction”.

  The edge position detection unit 307 specifies a position (coordinate) where the output value of the pixel adjacent in the width direction changes from a value smaller than the threshold to a value larger than the threshold, and outputs the position as an edge position of the paper P. The edge position detection unit 307 is an example of an “edge position detection unit that detects an edge of an object”.

  Next, an example of a process performed by the control device 300 will be described with reference to a flowchart of FIG.

  First, in step S601, the condition setting unit 304 sets conditions necessary for reading an edge position. The conditions to be set are, for example, conditions for preprocessing and conditions for edge detection processing, as described above. The condition setting unit 304 outputs the set values to the preprocessing unit 303, the signal level detection unit 305, the signal output addition processing unit 306, and the edge position detection unit 307, and necessary conditions are set in each unit.

  Next, in step S603, the control device 300 issues a command to drive the light source unit 211 and the light receiving unit 212 at a timing based on the clock signal from the drive clock generation unit 302. The command is issued to the AFE 213 via the communication unit 301. The light source unit 211 irradiates, at a predetermined timing, a region through which the edge of the conveyed sheet P passes in the width direction based on the drive signal from the AFE 213.

  The light receiving unit 212 outputs an analog voltage signal of one line of pixels to the AFE 213 at a predetermined timing based on the drive signal from the AFE 213. The AFE 213 performs A / D conversion, and outputs a digital voltage signal of one line of pixels to the control device 300.

  The communication unit 301 receives an output signal of one line of pixels and outputs the signal to the preprocessing unit 303. The pre-processing unit 303 performs pre-processing such as width-direction moving averaging processing and conveyance direction averaging processing, and outputs a pre-processing result to the signal level detection unit 305.

  Next, in step S605, the signal level detection unit 305 acquires the signal levels Vh and Vl in the output values of the pixels for one line. When the method for determining the threshold for edge detection is set to “automatic determination” by the condition setting unit 304, the signal level detection unit 305 calculates the threshold for edge detection from the acquired signal levels Vh and Vl. I do. The calculated threshold value is input to the edge position detection unit 307. The calculation is performed by, for example, the calculation of (Vh + Vl) / 2. When the threshold is not automatically determined, the threshold data recorded in the condition file is input to the edge position detection unit 307.

  Next, in step S607, the signal output addition processing unit 306 determines whether to perform the addition processing of the pixel output values based on the values of the signal level Vh and the signal level Vl. That is, when sufficient reflected light is obtained from the sheet P and the difference between the signal level Vh and the signal level Vl is large, it is determined that the signal output addition processing is not to be performed. When the difference between the signal level Vh and the signal level Vl is small, it is determined that the signal output addition processing is performed. This determination is not limited to the method using the detection results of the signal level Vh and the signal level Vl. Data such as the type, color, or surface state of the paper is recorded in a condition file in advance, and the data is referred to. Thus, the determination may be made.

  If it is determined in step S607 that signal output addition processing is to be performed, in step S609, the signal output addition processing unit 306 adds pixel output values for each position in the width direction. That is, for each position in the width direction, for example, the output value of the pixel of the pixel array 212r, the output value of the pixel of the pixel array 212g, and the output value of the pixel of the pixel array 212b are added. The output values of the pixels for one line obtained by the addition are input to the edge position detection unit 307.

  If it is determined in step S607 that the signal output addition processing is not to be performed, the signal output addition processing is not performed, and the output values of the pixels for one line of the pixel array are input to the edge position detection unit 307. In this case, for example, the output values of the pixels for one line of any one of the pixel arrays 212r, 212g, and 212b are input to the edge position detection unit 307.

  Next, in step S611, the edge position detection unit 307 specifies a position where the output value of an adjacent pixel in the width direction changes from a value smaller than the threshold to a value larger than the threshold, and outputs the position as an edge position of the sheet P. .

  Next, if the condition is set to read the edge positions of a plurality of portions of the sheet P in the transport direction, it is determined in step S613 whether the edge position has been read a predetermined position or a predetermined number of times. If it is determined in step S613 that the edge position has been read at the predetermined position or the predetermined number of times, the control device 300 ends the process. On the other hand, if it is determined that the sheet has not been read, the process returns to step S603, and the edge position of the sheet P is again read. As will be described later, when the edge positions at a plurality of locations are read, the inclination of the sheet P is obtained in addition to the position of the sheet P.

  The edge position reading device 100 executes the above processing to read the edge position of the sheet P. The position or inclination of the sheet P is detected based on the edge position of the sheet P. The correction device in the post-process corrects the position or inclination of the paper P based on the detection result.

  Next, the data read by the edge position reading device 100 and the operation and effect of the edge position reading device 100 will be described with reference to FIGS.

  FIG. 7 is a diagram illustrating a state in which the edge position reading device 100 reads the edge position of the sheet P, and the read data. 3A illustrates a state in which the sheet P is being transported along the transport path T in the direction indicated by the thick black arrow, and the edge W of the sheet P is read by the sensor unit 210.

  (B) shows the output values of the pixels for one line for the red light read by the pixel array 212r. The horizontal axis is the position (coordinate) of each pixel of the pixel array in the width direction. The vertical axis is the output value of the pixel. The broken line indicates the signal level Vh of the output value of the pixel, and the difference from the signal level Vl is shown as a range D. Two dashed lines 214 indicate the position of the edge W in the width direction and the position of one end 210a of the sensor unit 210, respectively. A dotted line indicates a threshold 215 for edge detection. Similarly, (c) and (d) show output values of pixels for one line for green light and blue light read by the pixel arrays 212g and 212b, respectively.

  In the area irradiated with light from the light source 211, the amount of light reflected from the area where the paper P is absent is small, and the output value of the pixel is small. On the other hand, the amount of light reflected from the region where the paper P is present increases due to reflection by the paper P, and the output value of the pixel increases. Therefore, the position of the edge W of the sheet P in the width direction can be read by detecting the position in the width direction at which the output value of the pixel changes from a small value to a large value. Note that an area where there is no paper P is hereinafter referred to as a “background area”.

  Here, conventionally, the position of the edge W of the paper P is read using the output value of the pixel corresponding to the color having the largest change among red, green, and blue. For example, in FIG. 7, the change in the output value of the pixel with respect to red light is greater than the change in the output value of the pixel with respect to green and blue light. This indicates that the color of the paper P is close to red, and the amount of red reflected light is large. In the example of FIG. 7, the position in the width direction of the edge W can be read by specifying the position where the output value R of the pixel for red light changes from a value smaller than the threshold 215 to a value larger than the threshold 215. it can.

  However, the paper P has various colors and surface states, and depending on the paper P, a sufficient amount of reflected light may not be obtained. For example, in FIG. 8, the output values of the pixels for red, green, and blue light are all smaller than the threshold 215. In this state, the color of the paper P is black and a sufficient amount of reflected light cannot be obtained with any color. In such a case, the position of the edge of the sheet P cannot be read.

  On the other hand, FIG. 9 shows a case where the threshold value for detecting the edge is lowered as compared with FIG. The dotted line is the threshold 216. In the example of FIG. 9, the output value of the pixel due to the reflected light from the paper P exceeds the threshold value 216 for any of the red, green, and blue lights. However, due to noise light such as dust in the background area, the output value of the pixel may increase even without paper. In FIG. 9, a pixel output 216a represents a pixel output due to noise light. If the threshold value 216 is reduced, the pixel output due to the noise light may exceed the threshold value. In such a case, it becomes impossible to accurately read only the edge position.

  In the edge position reading device 100 of the present embodiment, the output value of the pixel is added for each position in the width direction. For example, in FIG. 10, (a) is an output value of a pixel for red light, (b) is an output value of a pixel for green light, (c) is an output value of a pixel for blue light, and (d) is a width direction. The sum of the output values of the pixels for the red, green, and blue light is shown for each position in.

  By adding the output values of the pixels for the three colors of light, the output value can be increased as compared with the case where only a single color is used. Thus, it is possible to prevent the edge of the sheet from being unreadable due to an insufficient amount of reflected light from the sheet due to the color or surface state of the sheet. Also, since the difference between the output value of the pixel due to the noise light and the output value of the pixel due to the reflected light from the paper can be increased, it is possible to prevent the edge position of the paper from being erroneously read due to the noise light. Can be prevented.

  Further, since output values for light of different colors, red, green, and blue, are used as output values of pixels to be added, a difference in the amount of reflected light for each color of paper can be suppressed, and various colors can be used. The edge of the paper can be read.

  As described above, according to the edge position reading device 100 of the present embodiment, the edge position of the target object can be read without being restricted by the type of the target object.

  Note that, in the present embodiment, a configuration in which light close to white is irradiated and red, green, and blue lights are respectively received by the three pixel arrays has been described, but the present invention is not limited to this. For example, a configuration may be adopted in which light is emitted from three light sources of red, green, and blue, and reflected light of each color is received in a time-division manner by one pixel array.

  The color of light to be used is not limited to red, green, or blue, and other colors such as cyan, magenta, and yellow may be replaced or added. Also, the number of pixel arrays and light sources provided for each color may be increased or decreased.

  Further, if light from the object can be received with a sufficiently large output without irradiating the light, there is no need to have a light source for irradiating the object with light.

  Further, in the above description, an example in which the image forming apparatus reads the edge of the conveyed sheet in the width direction has been described, but the present invention is not limited to this. For example, the present invention can be applied to reading of an edge of a conveyed article or sheet or a moving article or sheet. The present invention is also applicable to reading edges in various directions of various objects such as stopped papers, sheets, and articles. Also, an example using reflected light from the target object has been described, but if the target object transmits or transmits light, the transmitted light of the target object or the transmitted light can be used to read the edge. Good.

[Second embodiment]
Next, an example of the edge position reading device according to the second embodiment will be described with reference to FIGS. In the second embodiment, the description of the same components as those in the above-described embodiment may be omitted.

  First, before describing the edge position reading device 100a according to the second embodiment, the influence of the reflected light of the background area in the edge position reading device will be described with reference to FIG.

  FIG. 11 is a schematic diagram of a state in which the sensor unit 210 reads the edge position of the sheet P being conveyed in the direction indicated by the thick black arrow, as viewed from the side. Here, the background area B is an area where the sensor unit 210 reads, and is an area where there is no paper P. The background area B is a belt surface of a transport belt for transporting the paper P, for example. The transport belt is a member that transports the paper P placed on the belt surface by moving the belt surface in the transport direction. In an area where the sensor section 210 reads, in an area where the sheet P is not present, the sensor section 210 faces the belt surface.

  Here, when light is applied to an area for reading the edge of the sheet P, if the amount of reflected light from the background area B, that is, the belt surface is large and the output value of the pixel in the pixel array is large, the reflected light of the sheet P The difference from the output value of the pixel becomes smaller. In particular, when the addition processing is performed by the signal output addition processing unit 306, the difference from the signal output of the pixel due to the reflected light of the paper P may be further reduced.

  The output of the pixel due to the light reflected from the background area B becomes noise with respect to the output of the pixel due to the light reflected from the paper P. Therefore, when the amount of reflected light from the background area B is large, the SNR (Signal to Noise Ratio) of the output signal of the pixel due to the reflected light of the paper P decreases. As a result, the edge position of the sheet P may not be correctly read.

  As shown in FIG. 12, the edge position reading device 100a according to the present embodiment includes an opening 218 that allows light to pass or pass through a portion facing the sensor unit 210 in a region where the sensor unit 210 reads the edge of the sheet P. Is provided. The opening 218 is, for example, a gap formed between two transport belts when transferring the paper P from one transport belt B1 to the next transport belt B2 in FIG. Since there is no belt surface in this area, even if the sensor unit 210 irradiates light, the light is not reflected on the belt surface, and the reflected light does not enter the sensor unit 210.

  Therefore, the reflected light from the background area B can be prevented, and the SNR of the output signal of the pixel due to the reflected light of the paper P can be secured. Thereby, the reading accuracy of the edge position of the sheet P can be ensured, and the edge position of the sheet P can be read correctly.

  The effects other than the above are the same as those described in the first embodiment.

[Third embodiment]
Next, an example of the edge position reading device according to the third embodiment will be described with reference to FIG. In the third embodiment, the description of the same components as those in the above-described embodiment may be omitted.

FIG. 13 is a diagram illustrating a state of reading an edge position by the edge position reading device 100b according to the third embodiment. FIG. 3A is a schematic diagram illustrating a state where the sensor unit 210 reads the edge position of the sheet P being conveyed in the direction indicated by the thick black arrow, as viewed from the side.
FIG. 2B is an enlarged view of the periphery of the sensor unit 210.

  As in the second embodiment, if an opening 218 is provided at a position facing the sensor unit 210 in a region where the sensor unit 210 reads the edge of the sheet P, light emitted from the sensor unit 210 passes. Reflected light is suppressed. However, when the space where the sheet P is conveyed is narrow, some members may be arranged near the opening 218 in some cases.

  In such a case, light that has passed through the opening 218 may be reflected by a member arranged near the opening 218 and may enter the sensor unit 210. The light reflected by the member may lower the SNR of the output signal of the pixel due to the light reflected on the sheet P, as described in the second embodiment.

As shown in FIG. 13, the edge position reading device 100b according to the third embodiment includes a light absorbing member 219 at a position facing the sensor unit 210 in an area where the sensor unit 210 reads the edge of the sheet P. And The light absorbing member 219 is, for example, black brushed paper.
By absorbing light, reflection on the surface is prevented.

  Irradiation light from the light source unit 211 in the sensor unit 210 is absorbed by the light absorbing member 219, and noise light incident on the sensor unit 210 is prevented. Therefore, the reflected light from the background area B can be prevented, and the SNR of the output signal of the pixel due to the reflected light of the paper P can be secured. Thereby, the reading accuracy of the edge position of the sheet P can be ensured, and the edge position of the sheet P can be read correctly.

  The effects other than the above are the same as those described in the first embodiment.

[Fourth embodiment]
Next, an example of the edge position reading device of the fourth embodiment will be described with reference to FIG. In the fourth embodiment, the description of the same components as those in the above-described embodiment may be omitted.

  FIG. 14 is a diagram illustrating a state of reading an edge position by the edge position reading device 100c according to the fourth embodiment. 3A is a schematic view of the edge position of the sheet P being conveyed in the direction indicated by the thick black arrow, and a state in which the sensor unit 210 reads the edge position of the sheet P from the side. FIG. 2B is an enlarged view of the periphery of the sensor unit 210.

  As in the second embodiment, if an opening 218 is provided at a position facing the sensor unit 210 in a region where the sensor unit 210 reads the edge of the sheet P, light emitted from the sensor unit 210 passes. Reflected light is suppressed. However, when the space where the sheet P is conveyed is narrow, some members may be arranged near the opening 218 in some cases.

  In such a case, light that has passed through the opening 218 may be reflected by a member arranged near the opening 218 and may enter the sensor unit 210. The light reflected by the member may lower the SNR of the signal output of the pixel due to the light reflected on the sheet P in the same manner as described in the second embodiment.

  As shown in FIG. 14, the edge position reading device 100c according to the fourth embodiment has a configuration in which a mirror 220 is provided at a position facing the sensor unit 210 in a region where the sensor unit 210 reads the edge of the sheet P. . The reflection surface of the mirror 220 is inclined at a predetermined angle with respect to the irradiation direction of the light from the sensor unit 210 so that the reflected light does not enter the sensor unit 210. Note that the mirror 220 is an example of a light reflecting surface.

  Irradiation light from the light source unit 211 in the sensor unit 210 is reflected by the mirror 220 in a direction different from the direction in which the sensor unit 210 is arranged. Accordingly, it is possible to prevent noise light from being incident on the sensor unit 210. The angle at which the reflected light from the mirror 220 does not enter the sensor unit 210 is obtained in advance by experiment or simulation, and the mirror 220 is adjusted to this angle and fixed.

  As described above, the reflected light from the background area B can be prevented, and the SNR of the signal output of the pixel due to the reflected light of the paper P can be secured. Thereby, the reading accuracy of the edge position of the sheet P can be ensured, and the edge position of the sheet P can be read correctly.

  The effects other than the above are the same as those described in the first embodiment.

[Fifth Embodiment]
Next, an example of the edge position reading device of the fifth embodiment will be described with reference to FIGS. Note that, in the fifth embodiment, the description of the same components as those of the already described embodiment may be omitted.

  The sheet is gripped by being sandwiched by a plurality of rollers, for example, and is placed on a transport belt and transported. At this time, the plurality of rollers may be inclined and placed on the transport belt due to a difference in the number of rotations of each of the plurality of rollers.

  FIG. 15 illustrates a state in which the sheet P is misaligned, that is, shifted in parallel in the width direction, and is conveyed while being inclined and placed on the conveyance belt. (A) is a state before the positional deviation of the paper P is corrected. (B) shows a state after the edge position of the sheet P has been read by the edge position reading device and the positional deviation of the sheet P has been corrected by the correction device in a later process. The position of the edge of the sheet P is corrected before and after the correction. However, the inclination of the sheet P remains.

  In the edge position reading device 100d of the present embodiment, the sensor unit 210d reads the edge positions of a plurality of different positions of the sheet P in the transport direction, and detects the inclination of the sheet P based on the result.

  FIG. 16 illustrates an example of how the sensor unit 210d reads the edge positions of a plurality of different places on the paper P, and “the output values of the pixels are added to the red, green, and blue light obtained at each place. Value ". (A) shows the reading position 1, the reading position 2, and the positional relationship between the reading position 3 and the sheet P. Although the position of the sensor unit 210d in the transport direction is shifted with respect to the sheet P for easy viewing, the sensor unit 210d is fixed and the sheet P is transported in reading. Then, the timing of reading by the sensor unit 210d is shifted, and a plurality of different positions on the sheet P, that is, the edge positions of the reading positions 1 to 3 are read.

  (B) shows the “value to which the output value of the pixel is added” at the reading location 1. That is, the output value of the pixel of the pixel array 212r, the pixel array 212g, and the pixel array 212b is a value added for each position in the width direction. (C) and (d) similarly show “the value obtained by adding the output values of the pixels” at the reading position 2 and the reading position 3.

  At the reading position 1, the edge position in the width direction of the sheet P is W3. At the reading positions 2 and 3, the edge positions in the width direction of the sheet P are W4 and W5, respectively. Since the sheet P is inclined, the edge position at each position has a different value.

  FIG. 17 illustrates an example of a functional configuration of a control device 300d included in the edge position reading device 100d according to the present embodiment. The edge position detection unit 307d detects the edge positions W3 to W5 by the same method as described in the first embodiment. In addition, the inclination of the sheet P is calculated from the edge positions W3 to W5, for example, by calculating tan-1 {(W5-W3) / L31}. Here, L31 is the distance from the reading point 1 to the reading point 3 in the transport direction. In the above description, three edge positions are read, but at least two edge positions may be read to obtain the inclination of the sheet P. As the number of read locations increases, the accuracy of tilt detection can be improved due to the averaging effect.

  FIG. 18 shows another example of a state in which the sensor unit 210d reads the edge positions of a plurality of different places on the sheet P in the edge position reading device 100d of the present embodiment. FIG. 18 shows a state in which the inclination of the sheet P is corrected based on the edge positions W7 and W6 read at the reading locations 1 and 2. (A) is before correction and (b) is after correction.

  In the edge position reading device 100d, the sensor unit 210d reads W7 and W6, and the edge position detection unit 307d calculates the inclination tan-1 {(W7-W6) / L76}. Here, L76 is the distance from the reading point 1 to the reading point 2 in the transport direction. The calculated inclination of the sheet P is output to the correction device and corrected by the correction device.

  In the edge position reading device 100d, an ideal position in the width direction of the sheet P is defined in advance, and the position of the sheet P with respect to the ideal position is determined based on the difference from the edge position detected by the edge position detection unit 307d. The shift may be calculated. For example, assuming that W6 is an ideal position in FIG. 18, the edge position detection unit 307d can calculate the displacement of the sheet P by calculating W7-W6. The calculated positional deviation of the sheet P is output to the correction device and corrected by the correction device.

  As described above, according to the edge position reading device 100d of the present embodiment, the position and inclination of the sheet can be detected based on the edge position of the read sheet.

  The effects other than the above are the same as those described in the first embodiment.

[Sixth Embodiment]
Next, an example of the edge position reading device of the sixth embodiment will be described with reference to FIGS. In the sixth embodiment, the description of the same components as those of the above-described embodiment may be omitted.

  As described above, the edge position reading device may erroneously detect the edge position when the output value of the pixel exceeds the threshold value due to dust or the like. In the present embodiment, such erroneous detection based on the output value of a pixel such as dust is prevented.

  FIG. 19 is a block diagram illustrating an example of a functional configuration of a control device 300e included in the edge position reading device 100e according to the present embodiment. The control device 300e includes a threshold pixel number detection unit 191 and a dust determination unit 192.

  The threshold pixel number detection unit 191 detects the number of pixels whose pixel output value exceeds a threshold value of the output value in a predetermined range in the width direction. The number of detected pixels is input to the dust etc. determination unit 192. If the number of detected pixels is smaller than the threshold value of the number of pixels in the predetermined range set in advance by the condition setting unit 304e, the dust determination unit 192 determines that the output value of the pixel is caused by dust or the like. Then, the determination result is output to the edge position detection unit 307e. The edge position detection unit 307e ignores the output value of the pixel determined to be caused by dust or the like in edge detection. Further, the predetermined range and the threshold value of the number of pixels can be arbitrarily changed by the condition setting unit 304e. The threshold pixel number detection unit 191 is an example of a pixel number detection unit. The edge position detection unit 307e is an example of an “edge position detection unit that detects an edge position of an object based on the output of the addition unit and the output of the pixel number detection unit”.

  FIG. 20 shows an example of data read by the edge position reading device 100e of the present embodiment. The horizontal axis represents the position in the width direction, and the vertical axis represents the output value of the pixel. The black circle plots show the sum of the pixel output values for red, green, and blue light, and the white circle plot shows the pixel output values for red light, for example, without such addition. Is shown. 193 indicated by a solid straight line indicates a threshold value for the output value of the pixel. The output 194 of dust and the like surrounded by a solid line circle indicates an output value of a pixel caused by dust and the like, and the output 195 of a sheet of paper surrounded by a dashed square indicates an output value of a pixel caused by the sheet P.

  For example, in the output 194 such as dust, the number of pixels that exceed the threshold value 193 among the red light pixel outputs, that is, the five white circle plots, is one. On the other hand, in the paper output 195, the number of pixels exceeding the threshold 193 is four among the five plots of white circles. Therefore, for example, if the predetermined range is set to 5 pixels and the threshold value of the number of pixels in the dust determination unit 192 is set to 2 pixels or more, the edge position can be correctly read without being affected by the output due to dust or the like. Become.

  On the other hand, in the output 194 such as dust, the output of pixels for red, green, and blue light, that is, the number of pixels exceeding the threshold 193 among the five plots of black circles is three. On the other hand, in the paper output 195, among the five white circle plots, the number of pixels exceeding the threshold 193 is five. Therefore, in this case, for example, if the predetermined range is set to 5 pixels and the threshold value of the number of pixels in the dust determination unit 192 is set to 4 pixels or more, the edge position can be correctly read without being affected by the output due to dust or the like. Becomes possible.

  FIG. 21 shows another example of data read by the edge position reading device 100e of the present embodiment. FIG. 21 explains the side effect when the threshold value of the number of pixels is set too large.

  In FIG. 21, the plot of black circles shows the sum of the output values of the pixels for red, green, and blue light, and the output 196 of black dust or the like surrounded by a solid circle is caused by black dust or the like. The output value of the pixel is shown. A plot 197 indicates a correct edge position, and a plot 198 indicates an erroneously detected edge position. The reason why the output value of the pixel is reduced in 196 is that dust and the like are black.

  In such a case, for example, if the predetermined range is 5 pixels and the threshold value of the number of pixels is 3 pixels or more, a plot 197 of a correct edge position is detected. If the number of pixels is five or more, an incorrect edge position plot 198 is detected. Therefore, when it is predicted that the size of dust or the like is small, or when addition of pixel outputs for red, green, and blue light is not performed, it is desirable to reduce the threshold value of the number of pixels.

  As described above, according to the present embodiment, the edge position can be correctly read without being affected by the output due to dust or the like, and the predetermined range and The threshold value of the number of pixels can be optimized.

[Seventh Embodiment]
In the seventh embodiment, the description of the same components as those of the already described embodiment may be omitted.

  As described in FIG. 5, the threshold value for edge detection may be automatically determined. In that case, for example, among the output values of the pixels in the width direction obtained by the sensor unit 210, the signal level Vh and the signal level Vl are used, and (Vh + Vl) / 2 is set as the threshold. However, the output value of the pixel due to the light reflected on the sheet P may not be stable, such as a transparent sheet or a metallic sheet.

  FIG. 22 shows an example. In FIG. 22, a portion 221 indicated by a solid-line square indicates an output value of a pixel due to light reflected by metallic paper. As shown in the figure, the output value greatly changes. In this case, if the threshold value is automatically obtained using the signal levels Vh and Vl, the edge position may not be correctly read.

  Thus, the edge position reading device 100f of the present embodiment detects the paper type and switches the method of determining the threshold value according to the paper type.

  FIG. 23 is a block diagram illustrating an example of a functional configuration of a control device 300f included in the edge position reading device 100f according to the present embodiment. The control device 300f has a paper type detection unit 222.

  The paper type detection unit 222 detects the type of paper being conveyed. For example, this is realized by referring to the paper type selected on the operation panel 23 or the like in the image forming apparatus and stored in the RAM. When detecting that the output value of the pixel is not stable due to the reflected light of the transparent sheet, metallic paper, or the like, the paper type detection unit 222 outputs the detection result to the condition setting unit 304f. In this case, the condition setting unit 304f does not automatically determine the threshold value of the pixel output value for edge detection, but sets the threshold value to a fixed value. On the other hand, when detecting that the output value of the pixel due to the reflected light is stable, the paper type detection unit 222 outputs the detection result to the condition setting unit 304f. In this case, the condition setting unit 304f sets so as to automatically determine the threshold value of the output value of the pixel for edge detection. Note that the condition setting unit 304f is an example of a threshold value determination method changing unit, and the paper type detection unit 222 is an example of a type detection unit.

  As described above, by switching the setting of the threshold value determination method according to the type of paper, the influence of the type of paper can be suppressed, and the edge position can be read correctly.

[Eighth Embodiment]
As described in the description of FIG. 5, the present embodiment relates to the widthwise moving average processing in the preprocessing unit 303. In the seventh embodiment, the description of the same components as those of the already described embodiment may be omitted.

  In the edge position reading device, when a rod lens is used, periodic output noise may be generated due to crosstalk of light beams passing through the rod lens. FIG. 24 shows an example of output noise having such a periodicity and an output value after the width direction moving average processing in the preprocessing unit 303. In FIG. 24, a solid line 241 is an output value before the width direction moving average processing, and a broken line 242 is an output value after the width direction moving average processing. Before the processing, there is a variation in the output value having a periodicity, whereas after the processing, the variation is suppressed.

  On the other hand, FIG. 25 illustrates an example of a side effect when the widthwise moving average processing is performed. In FIG. 25, dust 243 in a circle indicates the output of a pixel caused by one dust, and dust 244 in a circle indicates the output of a pixel caused by another dust. The enclosed portion 245 represents the output of the pixel due to the edge of the paper P. Also, the solid line plot is the output when the width direction moving average processing is not performed, and the broken line plot is the output when the width direction moving average processing is performed.

  As shown in FIG. 25, when the width direction moving average processing is not performed, the number of pixels in the dust 243 and the dust 244 exceeding the threshold value of the pixel output value is small. Is determined. However, when the width direction moving average processing is performed, the dust 243 and the dust 244 become a united lump, and the number of pixels exceeding the threshold value of the pixel output value increases. As a result, the dust 243 and the dust 244 are no longer determined as dust, resulting in erroneous detection of the edge position.

  Further, when dust or the like is output near the edge of the paper P, the two can be separated without performing the width direction moving average processing. Is detected, which causes erroneous detection of the edge position.

  In particular, when the processing of adding the output of the pixel to the red, green, and blue light is performed, the output due to dust or the like becomes large, which may cause a side effect of the above-described moving average processing in the width direction.

  Therefore, in the edge position reading device 100g of the present embodiment, the execution of the width direction moving average process is switched between a case where the addition process of the pixel output with respect to the red, green, and blue light is performed and a case where the addition process is not performed. .

  FIG. 26 is a block diagram illustrating an example of a functional configuration of a control device 300g included in the edge position reading device 100g according to the present embodiment. The control device 300g includes a width direction moving average process execution switching unit 246. The width direction moving average process execution switching unit 246 refers to the condition setting unit 304g, and performs the width direction moving average process so as not to execute the width direction moving average process when performing the addition process of the pixel outputs for the red, green, and blue lights. When the processing unit 303 is set and the addition processing is not performed, the preprocessing unit 303 is set to execute the widthwise moving average processing. As a result, output noise can be suppressed by the widthwise moving average processing while preventing side effects. The preprocessing unit 303 is an example of a moving average processing execution unit.

  Next, an example of the edge position reading device of the ninth embodiment will be described with reference to FIGS. Note that, in the ninth embodiment, the description of the same components as those of the already described embodiment may be omitted.

  The edge position reading device may erroneously detect an edge position when an output value of a pixel exceeds a threshold value due to a foreign substance such as dust. In the present embodiment, erroneous detection of the edge position due to the output value of the pixel of such a foreign substance such as dust is prevented, and accurate edge position detection is enabled.

  FIG. 27 is a block diagram illustrating an example of a functional configuration of a control device 300h included in the edge position reading device 100h of the present embodiment. The control device 300h includes a threshold pixel detection unit 308h and a light amount adjustment unit 309. In the present embodiment, the condition setting unit 304h sets conditions for detecting foreign matter such as dust. Similarly to the condition setting unit 304 of each of the above-described embodiments, it is also possible to set conditions for reading the edge position. Further, in the present embodiment, the edge position detection unit 307h specifies a position (coordinate) where the output value of the pixel adjacent in the width direction changes from a value smaller than the first predetermined threshold to a larger value, and Output as edge position.

  The threshold pixel detection unit 308h, which is an example of the threshold pixel detection unit, detects a threshold pixel whose output value is larger than a second predetermined threshold value in a state where there is no target in the edge reading area. In a state where there is no paper as an object of the edge reading in the edge reading area, ideally, the output value of the pixel should be within a predetermined range, so that a pixel having an output value larger than a predetermined threshold In some cases, it can be determined that the output value of this pixel is caused by a foreign substance such as dust. Therefore, threshold pixel detecting section 308 can also be called a foreign substance detecting section. As an example, the detection result of the threshold pixel detection unit 308 includes the output value of the threshold pixel and the position of the threshold pixel in the width direction. Note that the threshold pixel detection unit 308h may detect the threshold pixel in the entire detectable range in the width direction, or may detect the threshold pixel in a predetermined range.

  Then, the threshold pixel detection unit 308h instructs the display panel 23 (an example of a display unit) to display that there is a foreign substance. As a result, the user can know that there is a foreign substance such as dust that causes erroneous edge detection. The display on the display panel 23 may include information on the position of the foreign matter and the like.

  The light amount adjustment unit 309 adjusts the amount of light received by the light receiving unit 212. Specific examples include, but are not limited to, changing the amount of current to the LEDs of the CIS, changing the exposure time per line, and deflecting the amplification factor of the received light signal.

  The condition setting unit 304h according to the present embodiment determines the amount of light received by the light receiving unit 212 in a state where the sensor unit 210 does not have an object in an area where the edge of the object is to be read. Is set to be larger than the amount of light received by the light receiving unit 212 in. The condition setting unit 304h can arbitrarily set and change the detection range in the width direction of the threshold pixel detection unit 308h. The condition setting unit 304h can also arbitrarily change a predetermined threshold value of the output value of the threshold pixel detection unit 308h, a predetermined threshold value of the number of pixels, and the like.

  The edge position detection unit 307h is an example of an “edge position detection unit that detects an edge position of an object based on the output of the addition unit”. The edge position detection unit 307h detects the edge position based on an output of the addition unit in a state where the sensor unit reads the edge of the object when the object is present. Note that the edge position detection unit 307 in each of the above-described embodiments may also detect the edge position based on the output of the addition unit in a state where the sensor unit reads the edge of the target object in the area where the object is located. Is possible.

  As described above, the light amount received by the light receiving unit 212 in a state where the sensor unit 210 reads the edge of the object does not have an object is determined by the light receiving unit 212 in a state where the object is present in a region reading the edge of the object. Set larger than the amount of light received. Foreign matter such as dust can be detected when the paper is not under the sensor, and erroneous edge detection due to the foreign matter can be prevented.

  FIG. 28 is an explanatory diagram of the amount of reflected light during the edge detection processing and the foreign substance detection processing.

  Note that the edge detection process is a process that is performed in a state where the sensor unit 210 has an object in an area where the edge of the object is read. When there is an object, the edge position in the width direction of the object can be detected based on the position at which the output in the state with the object changes to a value larger than the first predetermined threshold value as described above.

  On the other hand, the foreign object detection process is a process executed in a state where the sensor unit 210 does not have an object in an area where the edge of the object is read. When there is no target object, the sensor unit 210 ideally detects a substantially constant output value from the background area. Therefore, if a threshold pixel exceeding a second predetermined threshold, which is a threshold at the time of foreign substance detection, is detected during the foreign substance detection processing, the presence of a foreign substance such as dust is detected at the width direction position corresponding to the threshold pixel. it can.

  FIG. 28 shows output values of pixels of one line of a certain light read by the pixel array 212 at the time of the foreign object detection treatment. The horizontal axis is the position (coordinate) of each pixel of the pixel array in the width direction. The vertical axis is the output value of the pixel.

  The dotted line in FIG. 28 indicates an output value under the same light amount condition as that at the time of the edge detection processing. Looking at the dotted line, the output value caused by the foreign matter 1 exceeds the threshold value α. On the other hand, the output value due to the foreign matter 2 does not exceed the threshold value α. When the threshold value α is the first predetermined threshold value that is a threshold value at the time of the edge detection processing, the foreign matter 2 is not detected, so that it does not cause erroneous edge detection. However, if the output value is close to the threshold value α, it may not be detected by chance due to variations in the reading itself. Further, as paper dust or the like is further accumulated in the foreign matter 2, the output value of the position of the foreign matter 2 gradually increases, and eventually, the end of the sheet is erroneously detected.

  For this reason, as shown by the solid line, control is performed so that the amount of reflected light detected by the sensor unit 210 during the foreign object detection processing is higher than during the edge detection processing. When both the first predetermined threshold value which is the predetermined value at the time of the edge detection processing and the second predetermined threshold value which is the predetermined value at the time of the foreign matter detection processing are the threshold value α, the output is relatively controlled by performing such control. Foreign matter having a small value is more easily detected.

  That is, as an example, irradiation light in a state where the sensor unit 210 does not have an object in an area where the edge of the object is read becomes larger than irradiation light in a state where the object is present in an area where the edge of the object is read, that is, when the edge is detected. Control. As a result, it becomes easier to detect foreign matter such as dust without the sheet under the sensor. Note that specific means for increasing the amount of reflected light include increasing the current of the CIS LED, but is not limited thereto.

  As another example, a detection signal corresponding to the amount of received light in a state where the sensor unit 210 does not have an object in an area where the edge of the object is to be read is a state in which the object is present in an area where the edge of the object is to be read, that is, when an edge is detected. Is controlled to be larger than the detection signal corresponding to the amount of received light at. Also in this case, it is easy to detect foreign matter such as dust without the sheet under the sensor. Specific means for increasing the detection signal include, but are not limited to, increasing the exposure time per line, increasing the amplification factor of the received light signal, and the like.

  Next, an example of the edge position reading device of the tenth embodiment will be described with reference to FIGS. In the tenth embodiment, the description of the same components as those of the above-described embodiment may be omitted.

  As described above, the edge position reading device 100 may erroneously detect the edge position when the output value of the pixel exceeds the threshold value due to a foreign substance such as dust. In the present embodiment, erroneous detection of the edge position due to the output value of the pixel of such a foreign substance such as dust is prevented, and accurate edge position detection is enabled.

  FIG. 29 is a block diagram illustrating an example of a functional configuration of the control device 300i included in the edge position reading device 100 according to the present embodiment. The control device 300i includes a threshold pixel detection unit 308i. In the present embodiment, the condition setting unit 304i sets conditions for detecting foreign matter such as dust. The condition setting unit 304i can also set conditions for reading the edge position, similarly to the condition setting unit 304 of each of the above-described embodiments. Further, the edge position detection unit 307i specifies a position (coordinate) where the output value of the pixel adjacent in the width direction changes from a value smaller than the first predetermined threshold to a larger value, and outputs the position as the edge position of the paper P. . The edge position detection unit 307i is an example of an “edge position detection unit that detects an edge of an object”.

  The threshold pixel detection unit 308i, which is an example of the threshold pixel detection unit, detects a threshold pixel whose output value is larger than a second predetermined threshold value in a state where the target is not present in an area from which an edge is read. In a state where there is no paper as an object of the edge reading in the edge reading area, ideally, the output value of the pixel should be within a predetermined range, so that a pixel having an output value larger than a predetermined threshold In some cases, it can be determined that the output value of this pixel is caused by a foreign substance such as dust. Therefore, threshold pixel detecting section 308 can also be called a foreign substance detecting section. As an example, the detection result of the threshold pixel detection unit 308 includes the output value of the threshold pixel and the position of the threshold pixel in the width direction. The threshold pixel detection unit 308i may detect the threshold pixel in the entire detectable range in the width direction, or may detect the threshold pixel in a predetermined range.

  In the present embodiment, the condition setting unit 304i sets the second predetermined threshold value in a state where the sensor unit 210 reads the edge of the target object in the area where the edge of the target object is read in the area where the edge of the target object is read in the state where the sensor unit 210 reads the edge of the target object. It is set smaller than a first predetermined threshold value when an object is present, that is, when an edge is detected.

  Then, the threshold pixel detection unit 308i instructs the display panel 23 to display that there is a foreign substance. The display on the display panel 23 may include information on the position of the foreign matter and the like.

  Note that the detection range of the threshold pixel detection unit 308i, the predetermined threshold of the output value, and the predetermined threshold of the number of pixels can be arbitrarily changed by the condition setting unit 304i. The edge position detection unit 307h is an example of an “edge position detection unit that detects an edge position of an object based on the output of the addition unit”. The edge position detection unit 307h detects the edge position based on an output of the addition unit in a state where the sensor unit reads the edge of the object when the object is present. Note that the edge position detection unit 307 in each of the above-described embodiments may also detect the edge position based on the output of the addition unit in a state where the sensor unit reads the edge of the target object in the area where the object is located. Is possible.

  Then, the threshold pixel detection unit 308i instructs the display panel 23 to display that there is a foreign substance. The display on the display panel 23 may include information on the position of the foreign matter and the like.

  As described above, in the present embodiment, the second predetermined threshold in a state where the sensor unit 210 does not have an object in the area where the edge of the object is read is a state where the object is in the area where the edge of the object is read, that is, Since the value is smaller than the first predetermined threshold value at the time of edge detection, foreign substances such as dust can be more easily detected in a state where the sheet is not under the sensor, and erroneous detection of an edge due to the foreign substances can be prevented.

  FIG. 30 is an explanatory diagram of threshold values at the time of edge detection processing and at the time of foreign matter detection processing. In FIG. 30, h shows the output values of the pixels for one line of a certain light read by the pixel array 212 during the foreign object detection treatment. The horizontal axis represents the position (coordinate) of each pixel in the pixel array in the width direction, and the vertical axis represents the output value of the pixel.

  The solid line in FIG. 30 is an output value when a foreign object 3 and a foreign object 4 are subjected to the foreign object detection processing. The output value resulting from the foreign substance 3 in FIG. 30 exceeds the threshold value β and the threshold value γ. On the other hand, the output value caused by the foreign substance 4 exceeds the threshold value γ but does not exceed the threshold value β. If the first predetermined threshold value at the time of edge detection is the threshold value β, the output value caused by the foreign matter 4 does not exceed the threshold value β, and therefore does not cause an edge and erroneous detection. However, if the output value is close to the threshold value β, it may not be detected by chance due to variations in the reading itself. Further, as paper dust and the like are further accumulated in the foreign matter 4, the output value of the position of the foreign matter 4 gradually increases, and eventually an erroneous detection of the end of the sheet is made.

  Accordingly, the second predetermined threshold value which is a threshold value at the time of detecting foreign matter is a threshold value γ shown in FIG. 30, the first predetermined threshold value β which is a threshold value at the time of edge detection, and the second predetermined threshold value It is smaller than a first predetermined threshold. As a result, foreign substances can be more easily detected.

  FIG. 31 is a flowchart illustrating a first example of the foreign object detection process.

  FIG. 31 shows a flow executed in the ninth embodiment and the tenth embodiment, for example. It is a flow which starts in a state where the sensor unit 210 does not have the target in an area where the edge of the target is read. The flow may be started at a timing instructed by the user or the like from the display panel 23 or the like, at a timing determined by the control unit 300, or automatically at a preset timing. Note that, as an example, at a timing when the sheet P is not conveyed on the conveyance path, the control device 300 determines that the object is not in the area where the sensor unit 210 reads the edge of the object. As another example, even when the sheet P is being conveyed along the conveyance path, the sensor unit 210 determines the timing at which the sensor unit 210 reads between the preceding sheet P and the succeeding sheet P. It may be determined that there is no object in a region where an edge is read.

  First, the condition setting unit 304 sets foreign matter detection conditions (S11). The foreign matter detection condition may be the same as the condition at the time of edge detection, or a condition suitable for foreign matter detection may be separately set. Next, the sensor unit 210 emits CIS based on the set conditions (S12). Then, the threshold pixel detection unit 308 detects a threshold pixel (S13). Then, the threshold pixel detection unit 308 determines the presence or absence of a foreign substance (S14). If it is determined in step S14 that there is a foreign substance, the pixel detection unit 308 causes the display panel 23 serving as a display unit to display that there is a foreign substance (S15), and the flow ends. On the other hand, if it is determined in step S14 that there is no foreign matter, the threshold pixel detection unit 308 displays that there is no foreign matter on the display panel 23 serving as a display unit (S16), and this flow ends.

  When the present foreign matter detection flow is executed in the ninth embodiment, a condition for increasing the amount of reflected light as described in FIG. 28 is set as one of the foreign matter detection conditions in step S11. When the present foreign matter detection flow is executed in the tenth embodiment, as one of the foreign matter detection conditions in step S11, the second predetermined threshold is set to be smaller than the first predetermined threshold as described with reference to FIG. What is necessary is just to make it small.

  Here, a specific example of the determination of the presence or absence of a foreign substance in step S14 of FIG. 31 will be described with reference to FIG. FIG. 32 is a diagram illustrating a state in which the edge position reading device 100 reads the edge position of the sheet P, and the read data.

  32A illustrates a state in which the sheet P is being conveyed along the conveyance path T in the direction indicated by the thick black arrow, and the edge W of the sheet P is read by the sensor unit 210. Further, FIG. 32 (a) shows the edge of the sheet P that is most shifted toward the sensor unit 210 due to the design of the image forming apparatus 500, and the edge position where the edge is most shifted toward the opposite side to W8. It is shown. In other words, due to the design of the image forming apparatus 500, the paper P does not shift toward the sensor unit 210 beyond B and does not shift toward the sensor unit 210 beyond W8.

  3B illustrates output values of pixels of one line of a certain light read by the pixel array 212. The horizontal axis is the position (coordinate) of each pixel of the pixel array in the width direction. The vertical axis is the output value of the pixel.

  As described with reference to FIG. 7, in the area irradiated with light from the light source unit 211, the amount of light reflected from the area where the paper P does not exist is small, and the output value of the pixel is small. On the other hand, the amount of light reflected from the area where the paper P is present increases due to reflection by the paper P, and the output value of the pixel increases. Therefore, the position of the edge W of the sheet P in the width direction can be read by detecting the position in the width direction at which the output value of the pixel changes from a small value to a large value.

  In FIG. 32, when a region that is a detection region as a sensor of the sensor unit 210 is a region R1, a region R2 that is closer to the sensor unit 210 than a region B that is a region where there is no possibility of sheet conveyance from the region R1. Is referred to as a “paper transport area”. In the determination of the presence or absence of a foreign substance in step S14, for example, when there is a foreign substance in the sheet transport area, it is determined that there is a foreign substance.

  Further, in the region R2, the left side of W8, that is, the region 3 is a region through which an edge portion when a sheet is shifted may pass due to the design of the image forming apparatus 500. Therefore, if foreign matter is present in this area, erroneous edge detection may occur. This area is referred to as a “area before the sheet passing position”. On the other hand, the region R4 is a region where the sheet is always conveyed even when the sheet is most displaced. The region R4 is referred to as a “sheet passing position region”. Even if a foreign substance is present in this region R4, since the paper passes between the sensor unit 210 and the foreign substance, the reflected light from the foreign substance is not received by the sensor unit 201. Does not occur.

  The condition setting unit 304 in each embodiment can appropriately set the detection range of the threshold pixel as one of the conditions of the edge detection processing and the foreign substance detection processing, such as the regions R1 to R4.

  That is, for example, when there is a threshold pixel in a predetermined region in the width direction set by the condition setting unit 304h and the condition setting unit 304i, for example, the threshold pixel detection unit 308h and the threshold pixel detection unit 308i output dust and the like. Although it is determined that the region is caused by the foreign matter, the setting of the predetermined region in the width direction set in advance can be appropriately set using the regions R1 to R4.

  Next, an example of the edge position reading device according to the eleventh embodiment will be described with reference to FIGS. In the eleventh embodiment, the description of the same components as those in the above-described embodiment may be omitted.

  As described above, the edge position reading device may erroneously detect the edge position when the output value of the pixel exceeds the threshold value due to foreign matter such as dust. In the present embodiment, erroneous detection of the edge position due to the output value of the pixel of such a foreign substance such as dust is prevented, and accurate edge position detection is enabled.

  FIG. 33 is a block diagram illustrating an example of a functional configuration of a control device 300j included in the edge position reading device 100j according to the present embodiment. The control device 300j includes a condition setting unit 304j, a threshold pixel detection unit 308j, and a threshold pixel detection result storage unit 309.

  In the present embodiment, the condition setting unit 304j sets a condition for the edge detection process as a condition for the foreign object detection process. As described in FIG. 6, the conditions at the time of the edge detection processing can take various variations such as a threshold value at the time of edge detection and whether to perform signal addition. In the present embodiment, a description will be given assuming that there are seven different edge detection processing conditions N (N = 0 to 6) shown in FIG. 34 as examples of the conditions of the edge detection processing. As shown in FIG. 34, seven different conditions can be set depending on the combination of “light emission amount” of the light source 201, “RGB signal addition presence / absence / detection color” of the sensor unit 210, and “threshold” at the time of edge detection. The condition setting unit 304j can also set the detection condition at the time of the foreign object detection processing, similarly to the condition setting unit 304 of each of the above-described embodiments.

  Further, the edge position detection unit 307j specifies a position (coordinate) where the output value of a pixel adjacent in the width direction changes from a value smaller than a first predetermined threshold to a larger value, and outputs the position as an edge position of the paper P. . The edge position detection unit 307j is an example of an “edge position detection unit that detects an edge of an object”.

  In the present embodiment, the threshold pixel detection unit 308j performs foreign object detection under the conditions at the time of the edge detection process set by the condition setting unit 304j. Then, the threshold pixel detection unit 308j outputs the foreign substance detection result executed under the conditions at the time of the edge detection processing to the threshold pixel detection result storage unit 309. The foreign matter detection result includes, but is not limited to, the presence or absence of a threshold pixel (foreign matter), the position of the threshold pixel (foreign matter), the number of threshold pixels (foreign matter), and the like. The threshold pixel detection result storage unit 309 stores the detection result output from the threshold pixel detection unit 308j.

  FIG. 35 is a flowchart illustrating a second example of the foreign object detection process.

  It is a flow which is started in a state where the sensor section does not have the object in an area where the edge of the object is read. The flow may be started at a timing instructed by the user or the like from the display panel 23 or the like, at a timing determined by the control unit 300, or automatically at a preset timing. Note that, as an example, at a timing when the sheet P is not conveyed on the conveyance path, the control device 300 determines that the object is not in the area where the sensor unit 210 reads the edge of the object. As another example, even when the sheet P is being conveyed along the conveyance path, the sensor unit 210 determines the timing at which the sensor unit 210 reads between the preceding sheet P and the succeeding sheet P. It may be determined that there is no object in a region where an edge is read.

  First, the condition setting unit 304j sets the variable N to 0 (S21). Then, the condition setting unit 304j sets the condition N, that is, the edge detection condition where N = 0 at first, as the foreign matter detection condition (S22). Next, the sensor unit emits CIS based on the set conditions (S23). Then, the threshold pixel detection unit 308j detects the threshold pixel (S24) and outputs the detection result to the foreign substance detection result storage unit 309. The threshold pixel detection result storage unit 309 stores the variable Nth detection result (S25). The condition setting unit 304j determines whether the execution of the foreign object detection processing has been completed under the all edge detection conditions (S26), and if not, increments N to N + 1 (S27), and proceeds to step S22. Return. If it is determined in step S26 that the process has been completed (S26), the flow ends.

  In the present embodiment, as in steps S22 and S23, the edge position detection unit detects the edge position when the sensor unit detects an edge position in a state where the sensor unit does not have the object in an area where the edge of the object is read. Having a plurality of detection conditions, the pixel detection unit, under the same condition as each of the plurality of edge position detection conditions in a state where the sensor unit does not have an object in the area to read the edge of the object, a pixel that is equal to or more than a predetermined threshold value To detect. Therefore, by performing the foreign object detection under a certain edge detection condition as in the present embodiment, the foreign object detected when the edge position detection is performed under the edge detection condition can be accurately grasped.

  FIG. 36 is an edge detection flowchart. This can be considered as an example of the edge position detection step S611 described with reference to FIG. First, printing is started under the edge position reading condition N (S31). The edge position detection / detection unit 307j refers to the threshold pixel detection result storage unit 309 and determines whether or not there is a threshold pixel, that is, a foreign substance in the threshold pixel detection result of the edge reading condition N (S32). When there is no foreign matter in step S32, the edge position detection unit 307j determines that printing, that is, image formation by the image forming unit 23 and detection of the edge position accompanying the printing are to be continued (S33), and printing is performed on the sheet whose edge position is to be read. Upon completion, this edge detection flow ends. On the other hand, if there is a threshold pixel in step S32, the process proceeds to step S34.

  As described above, in the present embodiment, in a state where the sensor unit does not have the target in the region where the edge of the target is to be read, the detection result in which the pixel that is equal to or more than the predetermined threshold is detected in advance under the edge position detection condition is detected. Accordingly, image formation is performed on the target object, so that image formation is performed in a state where there is a possibility that erroneous detection may occur in edge position detection, thereby preventing a shift in the image formation position.

  In step S34, the edge position detection unit 307j determines whether or not there is a threshold pixel before the sheet passing position in the sheet transport area (S34). If there is no threshold pixel before the sheet passing position, printing, that is, image formation by the image forming unit 23 is continuously executed (S33), printing is completed on the sheet whose edge position is to be read, and the present edge detection flow is performed. finish. On the other hand, if it is determined in step S34 that there is a threshold pixel in a predetermined position, for example, the area before the sheet passing position described with reference to FIG. 31, an alert is displayed on the operation panel 23 or the like. As a result, the user knows that there is a possibility of erroneous edge detection, and can take measures such as cleaning. As an example of the alert, there is a message indicating that there is a possibility of erroneous detection unless foreign matter is cleaned, but the alert is not limited to this.

  As described above, by performing or not performing the image formation in accordance with the position of the threshold pixel in step S34, the process frequently proceeds to step S35 and interrupts the image formation even when there is no influence on the edge detection processing. Can be prevented.

  In the present edge detection flowchart, the presence or absence of a threshold pixel is determined in step S32, and the presence or absence of a foreign substance requiring cleaning is determined in step S34 by dividing the position of the threshold pixel. However, another step may be added. If there is a threshold pixel in step S32 (NO), the process may proceed to step S35.

  As described with reference to FIG. 34, the example of the edge detection condition includes the light emission amount of the CIS, which color of RGB is to be lit as the detection color (including all colors), detection threshold (high / low) setting, and the like. However, it is not limited to these.

  When the foreign matter detection is performed using the condition for turning on each of RGB as an example of the edge detection condition, detailed information such as the position of the foreign matter according to the color of the foreign matter can be obtained. On the other hand, when the condition for lighting all the RGB colors is used, more foreign substances can be detected in one foreign substance detection process as compared with the case of performing each individual color.

  In addition, when a sensor cannot detect a foreign object due to a difference in the relative position between the foreign object and each of the RGB sensors, or the sensitivity of a sensor to a certain foreign object varies depending on the sensor due to a relationship between the color of the sensor and the color of the foreign object. There are cases. In this case, the edge detection processing may be performed by selecting the edge detection condition using a color in which no foreign substance is detected among the RGB, using the result of performing the foreign substance detection processing under the condition of individually emitting RGB.

  FIG. 37 is a diagram illustrating another configuration of the image forming apparatus 500 including the edge position reading device 100.

  The image forming apparatus 500 includes an exposure unit 101, an image forming unit 102, a transfer unit 103, and a fixing device 104. An operation panel 60 is provided above the image forming apparatus 500.

  The operation panel 60 as an example of the display unit receives various inputs according to the operation of the user, and receives various information (for example, information indicating the received operation, information indicating the operation status of the image forming apparatus 1, and image formation). (Information indicating the setting state of the apparatus 1). The operation panel 60 is constituted by, for example, a liquid crystal display (LCD) having a touch panel function, but is not limited to this. For example, it may be configured by an organic EL (Electro-Luminescence) display device equipped with a touch panel function. Further, in addition to or instead of this, an operation unit such as a hardware key or a display unit such as a lamp may be provided.

  The exposure unit 101, the image forming unit 102, the transfer unit 103, and the fixing device 104 each function as a part of a printer engine based on an instruction input from the operation panel 60 or the like, a printer function, a copy function, a facsimile function, It is hardware for realizing such as. That is, hardware such as a printer, a copy, a facsimile, and a scanner. As the printer function, an electrophotographic method, an ink jet method, or the like can be applied, but is not limited thereto.

  The image forming apparatus 500 can also have other specific options such as a finisher for sorting printed paper and an ADF (Auto Document Feeder) for automatically feeding a document. Hereinafter, the operation of each unit of the image forming apparatus 500 will be described.

  The image forming unit 102 includes a yellow (Y) photoconductor 120y, a black (K) photoconductor 120k, a magenta (M) photoconductor 120m, and a cyan (C) photoconductor 120c, each of which is an image carrier. . The image forming unit 102 also has a yellow (Y) developing unit 121y, a black (K) developing unit 121k, a magenta (M) developing unit 121m, and a cyan (C) developing unit 121c, each of which is a developing unit. . The image forming unit 102 further includes a yellow (Y) charger 122y, a black (K) charger 122k, a magenta (M) charger 122m, and a cyan (C) charger 122c, each of which is a charging unit. .

  The transfer unit 103 includes an intermediate transfer belt 130, a secondary transfer belt 133, and the like. The fixing device 104 serving as a fixing unit includes a fixing member 141, a discharge roller 142, and the like.

  The exposure unit 101 exposes the photoconductors 120y to 120c of the image forming unit 102, and emits writing light for writing a latent image corresponding to image data on each photoconductor. That is, a light beam is selectively emitted with a writing position corresponding to the image pattern of the image data and a writing light amount corresponding to the image density. As the writing light, light from a laser light source, an LED light source, or the like may be used. Hereinafter, as an example, a case where a laser light source having an LD (Laser Diode) is used will be described.

  First, the light beam BM emitted from the laser light source is deflected by the polygon mirror 110 and enters the scanning lenses 111a and 111b each including an fθ lens. The configuration and operation for emitting the light beam BM from the laser light source will be described later.

  The light beam is generated in a number corresponding to each color image of yellow (Y), black (K), magenta (M), and cyan (C). After passing through the scanning lenses 111a and 111b, the light beam is reflected. The light is reflected by the mirrors 112y to 112c.

  For example, the yellow light beam Y passes through the scanning lens 111a, is reflected by the reflection mirror 112y, and is incident on the WTL lens 113y. The same applies to the light beams K, M, and C of the respective colors of black, magenta, and cyan, so that the description thereof is omitted.

  The WTL lenses 113y to 113c shape the incident light beams Y to C, respectively, and then deflect the light beams Y to C to the reflection mirrors 114y to 114c. Then, the light beams Y to C are further reflected by the reflection mirrors 115y to 115c, and are irradiated on the photoconductors 120y to 120c as light beams Y to C used for exposure, respectively.

  Irradiation of the light beams Y to C to the photoconductors 120y to 120c is synchronized in timing in the main scanning direction and the sub-scanning direction with respect to the photoconductors 120y to 120c. The photoconductor has a drum shape long in the main scanning direction as an example, and may be a photoconductor drum.

  Hereinafter, the main scanning direction with respect to the photoconductors 120y to 120c is defined as the scanning direction of the light beam, and the sub-scanning direction is defined as the direction orthogonal to the main scanning direction, that is, the direction in which the photoconductors 120y to 120c rotate. I do. The main scanning direction corresponds to the sheet width direction, and the sub-scanning direction corresponds to the sheet conveyance direction.

  Each of the photoconductors 120y to 120c has a photoconductive layer including at least a charge generation layer and a charge transport layer on a conductive drum such as aluminum.

  The photoconductive layers are provided corresponding to the photoconductors 120y to 120c, respectively, and are charged by chargers 122y to 122c as a charging unit including a corotron charger, a scorotron charger, or a charging roller. A surface charge is applied according to the bias.

  The electrostatic charges applied to the photoconductors 120y to 120c by the respective chargers 122y to 122c are respectively exposed according to image patterns by light beams Y to C as writing light, and are scanned by the respective chargers 122y to 122c. An electrostatic latent image is formed on the surface.

  The electrostatic latent images formed on the scanned surfaces of the photoconductors 120y to 120c are respectively developed by developing units 121y to 121c which are developing units including a developing sleeve to which a developing bias is applied, a toner supply roller, a regulating blade, and the like. The image is developed and a toner image is formed on the scanned surface of the photoconductors 120y to 120c.

  Each developer carried on the scanned surfaces of the photoconductors 120y to 120c is transferred onto the intermediate transfer belt 130 moving in the direction of arrow D by the transport rollers 131a to 131c. 132y to 132c are primary transfer rollers for the photoconductors 120y to 120c, respectively.

  The intermediate transfer belt 130 as an image carrier is an example of an image forming unit in a state where the Y, K, M, and C developers transferred from the scanned surfaces of the photoconductors 120y to 120c are carried, respectively. The sheet is conveyed to the next transfer position 135.

  The secondary transfer belt 133 is stretched over transport rollers 134a and 134b, and further transported in the direction of arrow E by the rotation of the transport rollers 134a and 134b.

  Paper P, which is an object such as high quality paper or a plastic sheet, is conveyed by conveyance rollers 137a and 137b from a paper tray 136 which is an example of a storage unit such as a paper feed cassette toward the secondary transfer position 135.

  On the conveyance path to the secondary transfer position 135, a paper edge position reading device 100 is provided. The edge position reading device 100 reads the edge position of the paper P being conveyed, and grasps the conveyance position of the paper P. Then, after the edge position reading device 100 on the transport path to the secondary transfer position 135, a paper misalignment correction device 138 as a correction device 400 is provided. The paper misalignment correction device 138 has, for example, a plurality of roller pairs sandwiching the paper P, and controls the plurality of roller pairs according to the transport position of the paper P recognized by the edge position reading device 100 to adjust the transport angle of the paper P. To correct the image forming position.

  At the secondary transfer position 135, a secondary transfer bias is applied to transfer the toner image carried on the intermediate transfer belt 130 to the sheet P held by suction on the secondary transfer belt 133. The paper P is transported in a direction orthogonal to the main scanning direction. That is, the toner image formed on the surface of the intermediate transfer belt 130 is transferred to the sheet P at the secondary transfer position 135 which is an example of an image forming unit between the intermediate transfer belt 130 and the secondary transfer belt 133. .

  The paper P is supplied to the fixing device 104 as the secondary transfer belt 133 is transported.

  The fixing device 104 includes a fixing member 141 such as a fixing roller containing silicone rubber, fluorine rubber, or the like, presses and heats the sheet P and the toner image, and discharges the sheet P after image formation by the discharge roller 142. (Hereinafter, referred to as a sheet P ′).

  The density of the image on the sheet P ′ as an image carrier discharged from the fixing device 104 is detected by the density sensor 70. Based on the image density detected by the density sensor 70, density unevenness correction in the main scanning direction can be performed.

  After the transfer of the multicolor developer image, the intermediate transfer belt 130 is supplied to the next image forming process after the transfer residual developer is removed by a cleaning unit 139 including a cleaning blade.

  In the above-described operation of the printer engine, the rotation direction of the photoconductors 120y to 120c as image carriers, the direction of conveyance of the intermediate transfer belt 130 as the image carrier, and the direction of conveyance of the sheets P and P ′ as image carriers. Are all orthogonal to the main scanning direction and are the same as the sub-scanning direction.

  In FIG. 2, the density sensor 70 is disposed after the fixing device. However, if the density sensor 70 is installed, for example, in the vicinity of the transport roller 131a, it is also possible to detect the image density of the image formed on the intermediate transfer belt 130. .

  The image forming apparatus 500 illustrated in FIG. 36 operates in accordance with a command from the control device 300, similarly to the image forming apparatus 500 illustrated in FIG. In the image forming apparatus 500 of FIG. 1, the edge reading device 100 is installed after the fixing device 18 and reads an edge of a sheet on which an image is formed. On the other hand, in the image forming device 500 shown in FIG. Reference numeral 100 is provided before the secondary transfer position 138 which is an image forming unit, that is, reads an edge of the sheet P before image formation. In this case also, the effect of accurately reading the edge of the sheet P can be obtained.

  Although the image forming apparatus 500 has one edge reading apparatus 100 in FIGS. 1 and 36, it may have a plurality of edge reading apparatuses.

  As described above, the reading apparatus and the image forming apparatus according to the embodiments have been described, but the present invention is not limited to the above embodiments, and various modifications and improvements can be made within the scope of the present invention.

11, 12, 13, 136 Paper tray (storage section)
22, 135 Image forming unit 23, 60 Operation panel 100, 100h, 100i, 100j Edge position reading device 210, 210d Sensor unit (an example of a sensor unit)
211 Light source 212 Light receiving 213 AFE
300, 300h, 300i, 300j Control device 301 Communication unit 302 Drive clock generation units 304, 304h, 304i, 304j Condition setting unit (an example of a condition setting unit)
305 Signal level detection unit 306 Signal output addition processing unit (an example of an addition unit)
307, 307h, 307i, 307j Edge position detector (an example of an edge position detector)
308, 308h, 308i, 308j Threshold pixel detector (an example of a threshold pixel detector)
309 Light amount adjustment unit 310 Foreign matter detection result storage unit 400 Correction device 500 Image forming device

JP 2008-3286 A JP 2014-236260 A

Claims (10)

A reading device that detects an edge position in a width direction that is a direction intersecting with a transport direction of an object to be transported,
A sensor unit that has a pixel array in which a plurality of pixels that output a detection signal are arranged in the width direction, and is arranged so that the edge position can be read,
For each position in the width direction, an adding unit that adds output signals of the pixels of the pixel array,
An edge position detection unit that detects an edge position in the width direction of the object based on a position at which the output of the addition unit changes to a value larger than a first predetermined threshold,
The reading device, wherein the plurality of pixels output the detection signals according to the amounts of light received in different wavelength bands.   2. A pixel detection unit that detects a pixel whose output from the addition unit is larger than a second predetermined threshold value in a state where the sensor unit does not have the target in an area where an edge position of the target is read. 3. The reader according to the above.   3. The reading device according to claim 2, wherein a display indicating that there is a foreign substance is displayed on a display unit based on a detection result of the pixel detection unit. The sensor unit has a light source unit, the pixel array receives the reflected light of the irradiation light from the light source unit, the detection signal is a detection signal according to the amount of the reflected light received,
The reading device according to claim 2, wherein the irradiation light when detecting a pixel in a state where the object is not present is larger than the irradiation light when the edge detection unit detects an edge position. The sensor unit has a light source unit, the pixel array receives the reflected light of the irradiation light from the light source unit, the detection signal is a detection signal according to the amount of the reflected light received,
3. The detection signal according to the amount of received light when detecting a pixel in a state where the object is not present is larger than a detection signal according to the amount of received light when the edge detection unit detects an edge position. Reading device.   The reading device according to claim 2, wherein the second predetermined threshold is smaller than the first predetermined threshold. The edge position detection unit has a plurality of edge detection conditions that are detection conditions for detecting an edge position,
The pixel detection unit detects a pixel that is equal to or greater than a predetermined threshold under the same condition as each of the plurality of edge position detection conditions in a state where the sensor unit does not have the object in an area where the sensor unit reads an edge position of the object. 3. The reading device according to claim 2, wherein: A reading device according to claim 7,
An image forming apparatus having an image forming unit that forms an image on the object,
The pixel detection unit is configured to detect a pixel that is equal to or larger than a predetermined threshold value in advance in the edge position detection condition in a state where the sensor unit does not have the target in an area where the sensor reads the edge position of the target. An image forming apparatus configured to execute image formation on the object in response to the request.   The image forming apparatus according to claim 8, wherein image forming is performed when a pixel having a predetermined threshold or more is not detected in the detection result.   The image forming apparatus according to claim 8, wherein display is performed on a display unit according to a position of a pixel that is equal to or more than a predetermined threshold included in the detection result.