JP2012063560A - Detecting device of image carrier surface state and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detecting device of an image carrier surface state capable of improving a moving distance of a sensor per unit time by performing a continuous reciprocation without changing the rotating direction of a driving system when detecting the state of an image carrier surface by reciprocating a detecting means in the axial direction of the image carrier.SOLUTION: This detecting device of the image carrier surface state includes: an endless image carrier 1 (Y, M, C, and K) moving on the surface by rotating; detecting means 58 (Y, M, C, and K) detecting the surface state of the image carrier; and moving means 56 (Y, M, C, and K) supporting the detecting mans and reciprocating the detecting means in an image carrier axial direction (a) that orthogonally crosses with the surface moving direction of the image carrier. The moving means includes: spiral guide parts 80 and 81 (Y, M, C, and K) for forward and backward movements extending in the image carrier axial direction; sending members 60 (Y, M, C, and K) where end portions of the spiral guide parts for forward and backward movements are mutually continued; and drive means 41 (Y, M, C, and K) rotatingly actuating the sending members in one direction. The detecting means includes engagement parts 90 (Y, M, C, and K) to be engaged with the guide parts.

Description

  The present invention relates to an apparatus for detecting the surface state of an image carrier and an image forming apparatus including the apparatus.

Image forming apparatuses such as electrophotographic copying machines, printers, facsimiles, and multi-function machines having a plurality of these functions measure the amount of toner adhering to a photoconductor serving as an image carrier, and the state of the surface of the image carrier In order to detect this, one or a plurality of reflection density sensors serving as reflection density detection means are installed downstream of the developing device. In the image forming apparatus, the relationship between the result detected by the reflection density sensor and the toner adhesion amount on the photosensitive member is measured and set in advance by an experiment or the like. The toner density and image density are controlled appropriately.
In general, when there is a single reflection density sensor, it is installed at the center in the direction of the photoreceptor axis, and when there are a plurality of sensors, it is placed at intervals in the direction of the axis of the photoreceptor, and the values at a plurality of locations are measured. The toner density is estimated.

However, when there is one reflection density sensor, since the averaged toner density inside the developing device is estimated, the toner density accuracy is not guaranteed in the axial direction of the photoreceptor. When there are a plurality of reflection density sensors, it is possible to detect values at a plurality of locations in the axial direction of the photosensitive member, but this requires sensors for the necessary detection locations and increases costs. Even when a plurality of reflection density sensors are installed, it is difficult to measure the entire region with respect to the photosensitive body axial direction.
Therefore, in Patent Document 1, for the purpose of measuring the toner adhesion amount on the photosensitive member, one optical sensor serving as a reflection density detecting means is reciprocated using a moving means such as a screw or a wire in the axial direction of the photosensitive member. A configuration is disclosed in which the toner adhesion amount on the photoreceptor is detected.

  If one reflection density sensor can be moved in the axial direction of the photosensitive member, it is possible to control based on the measured value rather than estimating the toner adhesion amount on the entire photosensitive member at low cost. In addition, if the toner adhesion amount on the entire area of the photoconductor can be measured, it can be detected on the photoconductor when an abnormality such as a white streak occurs, and is controlled in the device before the abnormal printed matter is output. It is possible to reduce the output of abnormal images.

  In Patent Document 1, since one optical sensor is reciprocated in the direction of the photosensitive member axial line, the amount of toner adhesion on the entire surface of the photosensitive member can be estimated at a low cost, and can be controlled based on the measured value. Since an abnormality such as a streak is detected on the photoconductor, it can be controlled in the apparatus before an abnormal printed matter is output, and the output of an abnormal image can be reduced. However, since the moving means for reciprocating the optical sensor in the axial direction of the photoconductor is reciprocating with a screw or a wire, the rotation direction of the drive system is not changed when changing the moving direction of the optical sensor. The reciprocating motion will be intermittent. For this reason, when switching time is required and it is going to improve the movement distance of the sensor per unit time, there is a limit naturally.

  In the present invention, when detecting the state of the surface of the image carrier by reciprocating the detection means in the axial direction of the image carrier, continuous reciprocation can be performed without changing the rotation direction of the drive system. It is an object of the present invention to provide an image carrier surface state detection device that improves the movement distance of the hit sensor and an image forming apparatus including the same.

An image carrier surface state detection device according to the present invention is endless and detects a surface state of an image carrier that moves by rotating and supports the detection unit. Moving means for reciprocating in the axial direction of the image carrier perpendicular to the surface movement direction of the carrier.
This moving means has forward and backward spiral guide portions extending in the image carrier axis direction, and the end portions of the forward and backward spiral guide portions are continuous with each other. And a drive unit that rotationally drives the feed member in one direction, and the detection unit has an engaging portion that engages with the guide portion.

  In the image carrier surface state detection apparatus according to the present invention, the end portions of the forward and backward spiral guide portions are switching portions that are curved in the axial direction of the image carrier.

  In the image carrier surface state detection device according to the present invention, the relationship between the length of the engaging portion in the moving direction of the detecting means and the width in the direction intersecting the same plane with respect to this length is width <long. The end of the spiral guide part has an arc shape centered at an arbitrary point when the surface of the feed member is unfolded. The length of the leg portion constituted by a plurality of pins in the protruding direction with respect to the spiral guide portion is longer than the depth of the spiral guide portion.

  In the image carrier surface state detection device according to the present invention, the bottom of the leg portion is an ellipse, and the major axis of the ellipse is set shorter than the width of the spiral guide portion. .

In the image carrier surface state detection device according to the present invention, the relationship between the length of the engaging portion in the moving direction of the detecting means and the width in the direction intersecting the same plane with respect to this length is width <long. It has a leg portion that enters the spiral guide portion, and the end portion of the spiral guide portion has an arc shape centered at an arbitrary point when the surface of the feed member is developed, The width of the end portion of the shape is formed wider than the width of the guide portion other than the end portion.
In the image carrier surface state detection device according to the present invention, the width of the end portion of the arc shape is formed so that any two points of the leg portion are in contact with each other.

In the image carrier surface state detection apparatus according to the present invention, the feeding member extends to the outside of the image forming area of the image carrier.
The image carrier surface state detection apparatus according to the present invention is characterized by having a cleaning member for cleaning the detection surface of the detection means on one side or both sides of the feeding member located in the non-image forming area of the image carrier.
The image carrier surface state detection apparatus according to the present invention is characterized by having angle detection means for detecting the rotation angle of the feed member.

In the image carrier surface state detection device according to the present invention, the detecting means detects a detection toner image formed at a predetermined time or every predetermined number of prints at the end of the image forming area of the image carrier. It is a feature.
In the image carrier surface state detection apparatus according to the present invention, the detection means is an optical sensor that detects the surface state of the image carrier based on the difference in the amount of incident light.
In the image carrier surface state detection apparatus according to the present invention, the detection means is a contact detection sensor that detects the surface state of the image carrier by displacement of the contact pressure with the surface of the image carrier.
An image forming apparatus according to the present invention includes any one of the above image carrier surface state detection devices.

  According to the present invention, when the detecting means is reciprocated in the axial direction of the image carrier, the moving means is used for forward and backward movement extending in the axial direction of the image carrier whose ends are continuous with each other. A feed unit having a moving spiral guide and a drive unit that rotates the feed unit in one direction, and the detection unit is engaged with the guide unit via the engagement unit. Then, the detection means moves in the axial direction of the image carrier guided by the forward and backward spiral guide portions, and moves from one guide portion to the other guide portion via the continuous end portion. By doing so, the moving direction is switched. For this reason, it is not necessary to change the rotation of the feeding portion, and the engaging portion of the detecting means is moved from the forward spiral guide portion to the backward spiral guide or from the backward spiral guide portion to the forward spiral guide. When the position is switched, there is no need to decelerate the rotational speed of the driving means, which is the moving speed of the detecting means. For this reason, since the moving distance of the detection means per unit time in the axial direction of the image carrier is improved, the number of times that the detection means passes a specific point per unit time can be increased, and this specific point is detected by the detection means. By making the detection position by the above, the number of detections in the axial direction of the image carrier can be increased, and the state of the surface of the image carrier by the detection means can be measured more accurately.

1 is a schematic configuration diagram for explaining an overall configuration of an image forming apparatus according to the present invention. It is a figure which shows schematic structure of a process cartridge and an image carrier surface state detection apparatus. It is a perspective view which shows the structure of an image carrier surface state detection apparatus. FIG. 2 is a schematic view of the image carrier surface state detection device as viewed from the intermediate transfer member side. It is a partial expanded section which shows the structure of the moving means with which an image carrier surface state detection apparatus is provided. (A) is an expansion perspective view in which a detection means and an engaging part show the structure of a different body, (b) is an expansion perspective view in which a detection means and an engagement part show an integral structure. (A)-(e) is a perspective view which shows the form of the engaging part from which a leg part differs, and its structure. (A) is an expanded sectional view which shows the engagement state of the engaging part and guide part longer than the depth of a helical guide part, (b) is an engaging part and guide shorter than the depth of a helical guide part. It is an expanded sectional view which shows an engagement state with a part. (A) is an enlarged view for explaining the relationship between the forward and backward spiral guide portions and the engaging portion longer than the width of the guide portion, and (b) is the forward and backward spiral guides. It is an enlarged view explaining the relationship between an engaging part shorter than the width | variety of a part and a guide part. (A) is an enlarged view showing the shape of the end portion of the spiral guide portion for forward movement and backward movement, and (b) is the width of the spiral guide portion for forward movement and backward movement. It is an enlarged view which shows the shape of a different edge part. (A) is a plan view schematically showing a state in which a leg portion constituted by one pin moves an end portion having the same width, and (b) is a leg portion constituted by one pin and having a different width. It is a top view which shows the state which moves an edge part typically. (A) is a plan view schematically showing a state in which a leg part constituted by two pins reaches an end part of the same width from the guide part, and (b) is a leg part constituted by two pins. The top view which shows typically the state when approaching the edge part of the same width, (c) shows typically the state when the leg part comprised by two pins finishes passing the edge part of the same width. It is a top view. (A) is a plan view schematically showing a state when the plate-like leg portion reaches the end portion of the guide portion having a different width, and (b) is a state where the plate-like leg portion has entered the end portion having a different width. The top view which shows typically the state of time, (c) is a top view which shows typically the state when a plate-shaped leg part finishes passing the edge part of a different width | variety. (A)-(e) is an expanded sectional view which shows the form of the leg part from which bottom shape differs. (A) is a bottom view showing a configuration of an engaging portion having a leg portion constituted by three pins, and (b) is a leg portion constituted by three pins reaching an end portion of a guide portion having the same width. FIG. 4C is a plan view schematically showing a state when the leg is formed, FIG. 5C is a plan view schematically showing a state when the leg portion composed of three pins enters the end portion of the same width, and FIG. It is a top view which shows typically a state when the leg part comprised by 3 finishes passing the edge part of the same width. (A) is a schematic view of the image carrier surface state detection device in which the end of the spiral guide is connected in the circumferential direction, and (b) is an enlarged view of the end of the guide. It is. FIG. 3 is a schematic diagram illustrating a form in which a toner image for density detection is formed at an end of an image forming region of an image carrier to detect the position of a detection unit. It is a figure which shows typically the movement locus | trajectory of the detection means and the frequency | count of detection within the measurement time by the structure of the past and this application. (A)-(c) is an expanded sectional view which shows the form of a detection means. FIG. 6 is a diagram illustrating a relationship between a development potential and a toner adhesion amount on an image carrier. FIG. 4 is a diagram illustrating a relationship between a detection electromotive force of an optical reflection density sensor used in the present embodiment and a toner adhesion amount on an image carrier. (A) is a perspective view schematically showing a detection area by an optical reflection density sensor used in the present embodiment, and (b) is a plan view schematically showing a detection area by an optical reflection density sensor. It is a figure which shows the result of having measured the detection electromotive force from the same reflection density sensor, changing the area ratio to which the toner adheres in the detection area | region of an optical reflection density sensor. (A) is a plan view showing a state where there is no white stripe in the detection region of the optical reflection density sensor, and (b) shows a state where white stripes are generated in the detection region of the optical reflection density sensor. It is a top view. It is a figure which shows the state of the detection electromotive force output from the optical reflection density sensor accompanying the change of an image carrier surface state.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, the overall configuration of the image forming apparatus will be described, and then the image carrier surface state detection apparatus will be described. In each of the embodiments and modifications, components such as members and components having the same function or shape are given the same reference numerals as much as possible, and redundant description is omitted. In addition, the content described in embodiment is only one form, and the scope of the present invention is not limited to this.

The image forming apparatus shown in FIG. 1 is an electrophotographic printer (hereinafter simply referred to as a printer) 100. In this printer 100, the image forming unit will be described as a process cartridge.
In FIG. 1, a printer 100 includes four process cartridges 6Y, 6M, 6C, and 6K for generating toner images of yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K). Yes. These process cartridges use toners that constitute Y, M, C, and K developers of different colors as the image forming material, but are otherwise configured in the same manner. The process cartridge 6Y for generating the toner will be described as a representative.

  As shown in FIG. 2, the process cartridge 6Y is endless and rotates, so that the surface of the process cartridge 6Y moves as a drum-shaped photosensitive member 1Y, a drum cleaning device 2Y, a neutralizing device (not shown), and a charging device 4Y. And a developing device 5Y. The process cartridge 6Y is detachable from the apparatus main body of the printer 100, and is configured so that consumable parts can be replaced at a time.

  Here, the charging device 4Y employs a charging method in which the surface of the photoreceptor 1Y is uniformly charged by rotating the charging roller clockwise in the drawing by a driving unit (not shown). The uniformly charged surface of the photoreceptor 1 </ b> Y is exposed and scanned by the laser beam L to carry an electrostatic latent image for Y. The Y electrostatic latent image is developed into a Y toner image by the developing device 5Y using Y toner. In FIG. 1, intermediate transfer is performed on an intermediate transfer belt 8 serving as an intermediate transfer member located above the process cartridge 6Y.

  The drum cleaning device 2Y removes the toner remaining on the surface of the photoreceptor 1Y after the intermediate transfer process. A neutralization device (not shown) neutralizes residual charges on the photoreceptor 1Y after cleaning. By this charge removal, the surface of the photoreceptor 1Y is initialized and prepared for the next image formation. Similarly, in the other process cartridges 6M, 6C, and 6K, M, C, and K toner images are formed on the photoreceptors 1M, 1C, and 1K, respectively, and are positioned above the process cartridges 6M, 6C, and 6K. Each toner image is intermediately transferred onto the intermediate transfer belt 8.

  In FIG. 1, an exposure device 7 for irradiating each photoconductor with a laser beam L corresponding to each color is disposed below the process cartridges 6Y, 6M, 6C, and 6K. The exposure device 7 serving as a latent image forming unit irradiates the respective photoconductors in the process cartridges 6Y, 6M, 6C, and 6K with a laser beam L emitted based on the image information. By this exposure, electrostatic latent images for Y, M, C, and K are formed on the photoreceptors 1Y, 1M, 1C, and 1K. The exposure device 7 irradiates each photoconductor through a plurality of optical lenses and mirrors while scanning a laser beam L emitted from a light source with a polygon mirror rotated by a motor.

  On the lower side of the exposure apparatus 7 in the figure, paper supply means including a paper storage cassette 26, a paper supply roller 27 incorporated therein, a registration roller pair 28, and the like are disposed. In the paper storage cassette 26, a plurality of transfer papers P as recording media are stored in a stacked manner. The paper feed roller 27 is in contact with the uppermost transfer paper P in the paper storage cassette 26. The paper feed roller 27 is configured to be rotated counterclockwise in the drawing by a driving means (not shown), and the paper transfer cassette P is moved so that the uppermost transfer paper P faces between the rollers of the registration roller pair 28 by this rotation. 26 is fed.

  The registration roller pair 28 rotationally drives both rollers so as to sandwich the transfer paper P, but temporarily stops rotating immediately after being sandwiched, and feeds the transfer paper P toward a later-described secondary transfer nip at an appropriate timing. In the sheet feeding unit having such a configuration, a conveying unit is configured by a combination of the sheet feeding roller 27 and the registration roller pair 28 corresponding to the timing roller. This transport means transports the transfer paper P from a paper storage cassette 26 serving as a storage means to a secondary transfer nip described later.

  Above the process cartridges 6Y, 6M, 6C, and 6K in the figure, an intermediate transfer unit 15 that moves the intermediate transfer belt 8 endlessly while stretching is disposed. The intermediate transfer unit 15 includes an intermediate transfer belt 8, four primary transfer bias rollers 9Y, 9M, 9C, and 9K, a cleaning device 10, a secondary transfer backup roller 12, a cleaning backup roller 13, a tension roller 14, and the like. I have. The intermediate transfer belt 8 is endlessly moved in the counterclockwise direction in the figure by the rotational drive of at least one of the rollers 13, 14, 15 while being stretched around these three rollers 13, 14, 15. The primary transfer bias rollers 9Y, 9M, 9C, and 9K sandwich the intermediate transfer belt 8 that is moved endlessly between the photoreceptors 1Y, 1M, 1C, and 1K to form primary transfer nips, respectively. Yes.

  The intermediate transfer unit 15 is configured such that a transfer bias having a polarity opposite to that of the toner (for example, plus) is applied to the back surface (loop inner peripheral surface) of the intermediate transfer belt 8. All the rollers except the primary transfer bias rollers 9Y, 9M, 9C, and 9K are electrically grounded. The intermediate transfer belt 8 passes through the primary transfer nips for Y, M, C, and K sequentially along with the endless movement thereof, and the toner is transferred from the Y toner images on the photoreceptors 1Y, 1M, 1C, and 1K to the toner. Each toner image up to image K is superimposed and primarily transferred. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 8.

  The secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 between the secondary transfer roller 19 and forms a secondary transfer nip. The four-color toner image formed on the intermediate transfer belt 8 is secondarily transferred onto the transfer paper P at this secondary transfer nip. Transfer residual toner that has not been transferred to the transfer paper P adheres to the intermediate transfer belt 8 after passing through the secondary transfer nip, but this is cleaned by the belt cleaning device 10.

  At the secondary transfer nip, the transfer paper P is sandwiched between the intermediate transfer belt 8 and the secondary transfer roller 19 whose surfaces move in the forward direction, and conveyed in the direction opposite to the registration roller pair 28 side. The transfer paper P sent out from the secondary transfer nip is transferred to the surface by heat and pressure when passing between the rollers of the fixing device 20 disposed above (downstream) from the secondary transfer nip. A four-color toner image is fixed. After the fixing, the transfer paper P passes through between the rollers of the paper discharge roller pair 29 and is discharged to the stack unit 30 formed on the upper surface of the printer main body and sequentially stacked.

  Next, the configuration of the developing device will be described. Since each developing device has the same configuration except that the color of the toner is different, the developing device 5Y in the process cartridge 6Y shown in FIG. 2 will be described as a representative. The developing device 5Y includes a developing unit 51Y as a developer carrying member having a magnetic field generating means therein and carrying a two-component developer containing magnetic particles and toner on the surface, and carried on the developing sleeve 51Y. And a doctor 52Y as a developer regulating member that regulates the layer thickness of the conveyed developer. A uniaxial developer accommodating portion 53Y that accommodates the developer regulated by the doctor 52Y without being conveyed to the developing area facing the photoreceptor 1Y is formed upstream of the doctor 52Y in the developer conveying direction. Yes. In the developing device 5Y, a biaxial developer accommodating portion 54Y that is replenished with toner is formed adjacent to the uniaxial developer accommodating portion 53Y. Conveying screws 55Y and 55Y serving as two developer conveying members for agitating and conveying the developer are disposed in the one-axis developer accommodating portion 53Y and the two-axis developer accommodating portion 54Y, respectively.

  The operation of the developing device 5Y will be described. In the developing device 5Y, a developer layer is formed on the developing sleeve 51Y. The toner is replenished to the two-axis side of the developer conveying screw 55Y, is agitated and conveyed, and is taken into the developer. The toner is taken in so that the developer is within a predetermined toner density range. The toner taken into the developer is charged by frictional charging with the carrier. The developer containing charged toner is supplied to the surface of the developing sleeve 51Y having a magnetic pole inside and is carried by magnetic force. The developer layer carried on the developing sleeve 51Y is conveyed in the direction of the arrow by the rotation of the developing sleeve 51Y. During the course, the thickness of the developer layer is regulated by the doctor 52Y, It is transported to the opposite development area. In the development area, development based on the latent image formed on the photoreceptor 1Y is performed. The developer layer remaining on the developing sleeve 51Y is conveyed to the upstream portion in the developer conveying direction of the uniaxial developer accommodating portion 53Y as the developing sleeve 51Y rotates.

  In the vicinity of each photoconductor, an image carrier surface state detection device 200 (Y, M, C, K) having the same configuration is arranged. In FIG. 2, only the image carrier surface state detection device 200Y disposed in the vicinity of the photoreceptor 1Y is displayed. As shown in FIG. 3, the image carrier surface state detection device 200Y supports a reflection density sensor 58Y serving as detection means for detecting the surface state of the photoreceptor 1Y and the reflection density sensor 58Y. A sensor unit 56Y is provided as a moving unit that reciprocates in an image carrier axial direction (hereinafter referred to as “photosensitive axial direction”) a orthogonal to the surface moving direction of the photosensitive member 1Y.

  The sensor unit 56Y includes a cross screw screw 60Y serving as a feed member in which spiral grooves 80Y and 81Y serving as forward and backward spiral guide portions extending in the photosensitive body axial direction a are formed on the surface thereof. A sensor unit case 59Y that covers the cross screw 60Y and the reflection density sensor 58Y, and a main body drive source 41Y that is a driving unit that rotationally drives the cross screw 60Y in one direction are provided. The sensor unit 56Y is provided in the process cartridge 6Y for forming a Y toner image. The process cartridges M, C, and K are also provided with sensor units 56M, 56C, and 56K that are similar to the configuration of the sensor unit 56Y, respectively, although not shown. As shown in FIG. 2, the sensor unit 56Y is located between the developing device 5Y and the intermediate transfer belt 8, and is disposed so that the reflection density sensor 58Y and the surface of the photoreceptor 1Y face each other.

  FIG. 4 is a view of the cross screw 60Y, the reflection density sensor 58Y, and the photosensitive member 1Y as viewed from the intermediate transfer belt 8, but the sensor unit case 59Y is not shown for easy explanation. In FIG. 4, the cross screw 60Y is parallel to the rotation axis 1Ya of the photosensitive member 1 and extends in the photosensitive member axial direction a, and is supported so that the reflection density sensor 58Y and the photosensitive member 1Y face each other. is doing. The ends of the cross screw 60Y are rotatably supported by a pair of frames 61 and 62 positioned in the photosensitive member axial direction a. A transmission gear 63Y that meshes with a drive gear 64Y that is rotationally driven by the main body drive source 41Y is fixed to the end of the cross screw 60Y located outside the frame 62. The cross screw 60Y is rotationally driven integrally with the transmission gear 63Y when a driving force is input to the transmission gear 63Y.

  The spiral groove 80Y formed on the surface of the cross screw 60Y is used when the reflection density sensor 58Y is moved from the left to the right in FIG. 4 where the reflection density sensor 58Y moves forward. The spiral groove 81Y is the reflection density sensor 58Y. 4 is used when moving from right to left in FIG. 4, which is double-acting, and the phases of the two are shifted by 180 degrees and formed on the surface of the cross screw 60Y. The spiral groove 80Y and the spiral groove 81Y partially intersect to form an intersection L.

  The sensor unit 56Y is configured to reciprocate in the photosensitive member axial direction a when the cross screw 60Y is rotationally driven in one direction. The length of the cross screw 60Y in the photosensitive member axial direction a may be approximately the same as that of the photosensitive member 1Y, but in this embodiment, it is longer than the entire length of the photosensitive member 1Y. That is, the cross screw 60Y extends to the outside of the image forming area of the photoreceptor 1Y, and the reflection density sensor 58 can stand by at a position that does not face the photoreceptor 1. For example, when the printer 100 is not in operation, as shown in FIG. 4, the sensor unit 56Y can be placed as an initial position in a region not facing the photosensitive member 1, and the sensor surface is prevented from being stained with toner. be able to.

  When a cleaning member 70Y for cleaning the measuring unit 58Y1 of the reflection density sensor 58Y is disposed on one side or both sides of the non-image forming area of the photoconductor 1Y, for example, at the end that becomes the non-image forming area of the photoconductor 1Y in FIG. The toner adhering to the measurement unit 58Y1 of the reflection density sensor 58 can be removed, and the toner density on the photoreceptor 1Y can be detected with high accuracy. As a form of the cleaning member 70Y, the toner may be removed by rubbing the measuring unit 581Y of the reflection density sensor 58 with a brush or the like, or the toner may be removed by ejecting air. .

  As shown in FIGS. 3 and 5, a linear sensor guide 59Yb extending in the photosensitive member axial direction a is provided on the inner surface 59Ya of the sensor unit case 59Y. In the reflection density sensor 58Y, a linear sensor guide groove 58Yb is formed on the surface opposite to the detection surface 581Y so as to engage with the sensor guide 59Ya.

  The cross screw 60Y is rotated by the transmission gear 63Y. Since the transmission gear 63Y receives a driving force from the main body drive source 41Y, the existing main body drive source 41Y provided in the printer 100 can be used to drive the cross screw 60Y. This eliminates the need for a stepping motor and forward / reverse motor unlike the clutch and the prior art, reducing the number of parts and reducing the cost.

  As shown in FIGS. 3 and 4, a circular detection plate 65Y that rotates integrally with the screw is fixed to the end of the cross screw 60Y. An angle detection means 71Y such as a rotary encoder for reading the rotation angle of the cross screw 60Y from the detection plate 65 is disposed at a portion facing the detection plate 65. Since the rotation angle of the cross screw 60Y corresponds to the moving distance of the reflection density sensor 58Y in the photosensitive body axial direction a, the position of the reflection density sensor 58Y can be detected by the angle detection means 71Y and the detection plate 65. .

  As shown in FIGS. 6A and 6B, the reflection density sensor 58Y is engaged with the spiral groove 80Y at the time of forward movement, and a cross serving as an engagement portion that engages with the spiral groove 81Y at the time of forward movement. A screw screw guide member 90Y is provided. The cross screw screw guide member 90Y is a surface different from the detection surface 581Y of the reflection density sensor 58Y, and is inserted into and supported by the recess 58Yb formed on the surface opposite to the surface where the sensor guide groove 58Ya is formed. 91Y and a leg portion 92Y that engages with the spiral groove 80Y and the spiral groove 81Y of the cross screw 60Y.

  In this embodiment, the main body portion 91Y and the leg portion 92Y are inserted into the concave portion 58Yb and the helical groove 80Y and the helical groove 81Y of the cross screw 60Y, respectively, and the leg portion 92Y is guided by the respective grooves and is movably fitted. Yes. Therefore, in the reflection density sensor 58Y, the sensor guide groove 58Ya is engaged with the sensor guide 59Yb, and the cross screw screw guide member 90Y is supported on the surface opposite to the cross screw screw 60Y. When 60Y rotates and moves in the photosensitive member axial direction a, it is supported and movable so as not to tilt in the rotating direction.

  In this embodiment, the reflection density sensor 58Y and the cross screw screw guide member 90Y are formed separately, and the main body portion 91Y of the cross screw screw guide member 90Y is inserted into the concave portion 58Yc of the reflection density sensor 58Y to integrate them. As shown in FIG. 6 (b), a protrusion 93Y serving as an engaging portion is integrated with a surface that is different from the detection surface 581Y of the reflection density sensor 58Y and is opposite to the surface on which the sensor guide groove 58Ya is formed. The cross screw screw guide member 90Y may be formed.

  As shown in FIG. 6A, when the reflection density sensor 58Y and the cross screw screw guide member 90Y are formed as separate members, the leg portion 92Y can have a rectangular parallelepiped shape in addition to the cylindrical shape. It becomes. At this time, it is preferable that the cross screw screw guide member 90Y rotates with respect to the reflection density sensor 58Y that is a target portion to be moved. As shown in FIG. 6B, in the case where the reflection density sensor 58Y and the cross screw screw guide member 90Y are integrally formed, the projection 93Y is desirably a cylindrical shape.

  The reflection density sensor 58Y slides along the spiral groove 80Y and the spiral groove 81Y when the cross screw screw guide member 90Y receives a force from the cross screw screw 60Y as the cross screw screw 60Y rotates.

  FIG. 7 shows a form of the cross screw screw guide member 90Y. A cross screw screw guide member 90Y shown in FIGS. 7A to 7E is composed of a main body 91Y and a leg 92Y. In the configuration of FIG. 7A, the leg portion 92Y has a square shape, and in the configurations of FIG. 7B to FIG. 7D, the leg portion 92Y has a cylindrical shape. 7 (b), the leg portion 92Y is composed of one cylindrical pin, FIG. 7 (c) is the leg portion 92Y composed of two cylindrical pins, and FIG. 7 (d) is the leg portion. 92Y is composed of three cylindrical pins. The configuration of FIG. 7 (e) is a combination of the configurations of FIG. 7 (a) and FIG. 7 (c), and the two pins are connected by a plate-like member, It is a thing. In FIG. 7, the symbol D indicates the length of the leg 92 </ b> Y with respect to the moving direction of the reflection density sensor 58 </ b> Y, and the symbol M indicates the width of the leg 92 </ b> Y in a direction that intersects the length D in the same plane. And leg part 92Y other than FIG.7 (b) is formed so that it may become width M <length D. FIG.

  As shown in FIG. 8 (a), the spiral screw 80Y and the spiral groove 81Y of the cross screw screw guide member 90Y and the cross screw screw 60 are formed such that the bottom surface 92Ya of the leg 92Y is the bottom surface 80Ya and 81Ya of the spiral groove 80Y and the spiral groove 81Y. 8B, and the bottom surface 91Ya of the main body portion 91Y is in contact with the surface of the cross screw screw 60Y, and the bottom surface 92Ya of the leg portion 92Y. And the bottom surfaces 80Ya and 81Ya of the spiral groove 80Y and the spiral groove 81Y are separated. That is, when the length J1 of the leg portion 92Y in the protruding direction with respect to the spiral groove is formed longer than the depth J2 of the spiral groove 80Y and the spiral groove 81Y, as shown in FIG. When the bottom surface 92Ya of the leg portion 92Y is in contact with the bottom surfaces 80Ya and 81Ya of the groove 81Y, and the length J1 of the leg portion 92Y in the protruding direction with respect to the spiral groove is set shorter than the depth J2 of the spiral groove 80Y and the spiral groove 81Y, As shown in FIG. 8B, the bottom surfaces 80Ya and 81Ya of the spiral groove 80Y and the spiral groove 81Y are separated from the bottom surface 92Ya of the leg portion 92Y.

  When the cross screw screw guide member 90Y reciprocates in the photosensitive member axial direction a, as shown in FIGS. 9A and 9B, the cross screw screw 60Y and the spiral groove 81Y intersect each other. The leg portion 92Y needs to pass through the portion L. The leg portion 92Y of the cross screw screw guide member 90Y is a single cylindrical pin having a circular bottom surface as shown in FIG. 7B, and the length D (diameter) relative to the traveling direction is that of each spiral groove. When the width is smaller than the width A (D <A), since the leg 92Y moves in the spiral groove 80Y or the spiral groove 81Y and enters the intersecting portion L, the force received from the walls of each groove is lost. The guide member 90Y loses propulsive force at the intersection L. If the cross screw 60 continues to rotate at this time, the cross screw screw guide member 90Y may move in a direction different from the original direction indicated by the solid line arrow, as shown by the dotted arrow in FIG. 9B. There is. That is, there is a possibility that what has to move in the spiral groove 80Y enters the spiral groove 81Y at the intersection L.

  On the other hand, as shown in FIGS. 7A and 7C, when the length D of the cross screw screw guide member 90Y in the traveling direction of the leg portion 92Y is larger than the width A of the spiral grooves 80Y and 81Y. (D> A) Even when the leg 92Y enters the intersection L, the length D of the leg 92Y is larger than the width A of the groove, so that the leg 92Y passes through the intersection L. As described above, the force received from the cross screw 60 is not lost, and the crossing portion L can be passed while maintaining the propulsive force. Therefore, the cross screw screw guide member 90Y can stably pass through the crossing portion L without proceeding in the wrong direction, and stable movement can be performed.

  Next, the configuration of the end portions of the spiral grooves 80Y and 81Y will be described. As shown in FIGS. 3 and 4, the ends on both sides of the spiral groove 80Y and the spiral groove 81Y respectively form arc-shaped end portions 601Y and 602Y that are continuous with each other, and the end portions 601Y and 602Y The spiral groove 80Y and the spiral groove 81Y are endless (continuous). The shapes of the end portions 601Y and 602Y are basically the same.

  As shown in FIG. 10A, the end portions 601Y and 602Y have the same arc center point N between the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb of the grooves forming the end portions 601Y and 602Y. As shown in FIG. 10B, the width A1 of the portions 601Y and 602Y is the same as the width A of the groove, and as shown in FIG. 10B, the arcs of the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb of the grooves forming the end portions 601Y and 602Y The curvature is different due to the difference between the center points N and N1, and the longest width A2 of the end portions 601Y and 602Y is wider than the width A of the groove. That is, as shown in FIG. 10A, the end portions 601Y and 602Y constitute a switching portion that is curved toward the photoreceptor axial direction a, and an arbitrary point is obtained when the surface of the cross screw screw 60 is developed. The arc shape of the same center centered on N and the arc shape of different centers centering on different arbitrary points N and N1 when the surface of the cross screw screw 60 is developed. There is a shape in which the longest width A2 of the end portion is formed wider than the width A of the spiral grooves 80Y and 81Y. The shape of the end portions 601Y and 602Y is determined in consideration of the shape of the leg portion 92Y of the cross screw screw guide member 90Y.

  As described above, the relationship between the cross screw screw guide member 90Y and the spiral grooves 80Y and 81Y is that the bottom surface 91Ya of the main body 91Y and the cross screw screw 60 are not in contact with each other as shown in FIG. When the bottom surface 92Ya of the leg portion 92Y is in contact with and supported by the bottom surfaces 80Ya and 81Ya of the spiral grooves 80Y and 81Y, and as shown in FIG. 8B, the bottom surface 80Ya and 81Ya of the leg portion 92Y and the spiral grooves 80Y and 81Y. Are not in contact with each other, and the bottom surface 91Ya of the main body 91Y and the cross screw 60 may be in contact with each other to be supported.

  In the case where the shape of the leg portion 92Y of the cross screw screw guide member 90Y is constituted by a single bottom cylindrical pin as shown in FIG. 7B, the end portions 601Y of the spiral grooves 80Y, 81Y, By making the shape of 602Y into the shape shown in FIG. 10A, the reflection density sensor 58Y (cross screw screw guide member 90Y) can continuously move.

  Explaining this point in detail, as shown in FIG. 11A, the shapes of the end portions 601Y and 602Y of the spiral grooves 80Y and 81Y formed in the cross screw 60 are the shapes shown in FIG. When the width of each groove is set to the width A including the end portion (A = A1), as shown in FIG. 8A, the bottom surface 92Ya of the leg portion 92Y and the bottom surfaces 80Ya and 81Ya of the spiral grooves 80Y and 81Y. 8A, or a support method in which the bottom surface 91Ya of the main body 91Y and the cross screw 60 are in contact with each other, as shown in FIG. 8B. This is because, even if the cross screw screw 60 rotates and the cross screw screw guide member 90Y moves, the leg portion 92Y is supported from the side by the inner wall 601Ya, 602Ya and the outer wall 601Yb, 602Yb of each spiral groove. This is because the cross screw screw guide member 90Y can move continuously without falling down.

  As shown in FIG. 11B, the shapes of the end portions 601Y and 602Y of the spiral grooves 80Y and 81Y are the curvatures of the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb of each spiral groove as shown in FIG. , The longest width A2 at the end portions 601Y and 602Y is widened, the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb cannot support the leg portion 92Y from the side, and the leg portion 92Y No power from the wall. In such a state, it is conceivable that the leg portion 92Y is inclined and the main body portion 91Y and the reflection density sensor 58Y are detached from the respective spiral grooves. Further, since the leg portion 92Y loses propulsive force and remains stationary for a moment, it is assumed that the leg portion 92Y cannot be bent at the end portions 601Y and 602Y that are continuous folded portions. Therefore, when the leg portion 92Y is constituted by a single cylindrical pin, the end shape of the groove is such that the width A of the spiral grooves 80Y, 81Y is the end portions 601Y, 602Y as shown in FIG. It is desirable that the width A be in contact with the leg 92Y from the side surface with respect to the traveling direction of the leg 92Y.

  When the shape of the leg portion 92Y of the cross screw screw guide member 90Y is constituted by two cylindrical pins as shown in FIG. 7C, and the width M <length D, the cylindrical 1 For the same reason as in the case of the cross screw screw guide member 90Y constituted by a single pin, the shape of the groove at the end of the cross screw screw 60 is set to the shape shown in FIG. When the reflection density sensor 58Y moves in the photosensitive body axial direction a and passes through the end portions 601Y and 602Y, the reflection density sensor 58Y can be folded without deceleration.

  The folding operation of the leg 92Y at the ends 601Y and 602Y of the spiral grooves 80Y and 81Y when the leg 92Y is constituted by two pins will be described with reference to FIG. In FIG. 12, of the two pins of the leg portion 92Y, a pin positioned in the traveling direction is indicated by a symbol E, and a pin positioned backward in the traveling direction is indicated by a symbol F.

  When the cross screw 60 rotates, a force is transmitted from, for example, the spiral groove 80Y to the two pins E and F of the leg 92Y and moves toward the end 601Y as shown in FIG. Then, the pin E enters the end portion (folded portion) 601Y, performs a folding operation along the end portion 601Y, and changes its traveling direction. As time passes, the pin F located behind the pin E enters the end portion (folded portion) 601Y and occupies an arrangement in which the pin E and the pin F straddle the inner wall 601Ya as shown in FIG. . As time passes, as shown in FIG. 12C, the pin E passes through the end (folded portion) 601Y, the pin F passes through the end (folded portion) 601Y, and the leg portion 92Y passes through the spiral groove 80Y. Is guided to the spiral groove 81Y, and the folding operation is performed. For this reason, the reflection density sensor 58Y can reverse the traveling direction without decelerating when passing through the end portion (folded portion) 601Y. In addition, when the leg portion 92Y passes through the end portion (folding portion) 602Y, the same operation as the end portion (turning portion) 601Y is performed, so that the reflection density sensor 58Y passes through the end portion (turning portion) 602Y. The direction of travel can be reversed without slowing down.

As shown in FIG. 8 (a), the cross screw screw guide member 90Y and the spiral grooves 80Y and 81Y are in contact with each other as shown in FIG. 8 (a) where the bottom surface 92Ya of the leg 92Y and the bottom surfaces 80Ya and 81Ya of the spiral grooves 80Y and 81Y are in contact. In the method, the cross screw screw guide member 90Y can continuously move without falling down.
As shown in FIG. 8B, even in the support method in which the bottom surface 91Ya of the main body 91Y and the cross screw 60 are in contact, the bottom Ya of the main body 91Y and the cross screw 60 are rubbed. The screw guide member 90Y can move continuously without falling down.

  As shown in FIG. 10B, the shapes of the end portions 601Y and 602Y of the spiral grooves 80Y and 81Y formed on the cross screw 60 are formed by arcs having different curvatures between the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb. In the case of the shape, the longest width A2 is wider than the width A of the groove, and the pins E and F cannot be supported by the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb of the end portions 601Y and 602Y, and the propulsive force is lost. For the same reason as the case where the leg portion 92Y is configured with one pin described with reference to (b), the end portions (turned-back portions) 601Y and 602Y cannot be bent continuously. Therefore, also in the case of the cross screw screw guide member 90Y in which the leg portion 92Y is constituted by two cylindrical pins, the shapes of the end portions 601Y and 602Y are preferably the shapes shown in FIG.

  When the shape of the leg portion 92Y of the cross screw screw guide member 90Y is a plate shape as shown in FIG. 7A and the width M <length D, the end portions 601Y of the spiral grooves 80Y, 81Y When the shape of 602Y is a shape having the same width A1 (A = A1) as the width A of the spiral grooves 80Y and 81Y, as shown in FIG. 10A, the cross screw screw 60 is rotated and the cross screw screw is rotated. When the guide member 90Y moves in the photosensitive member axial direction a, the plate-like leg portion 92Y is caught by the inner and outer walls of the spiral grooves 80Y and 81Y and is bent as shown in FIGS. 13 (a) and 13 (b). I can't do better. Accordingly, the end portions 601Y and 602Y of the spiral grooves 80Y and 81Y are formed into arc shapes having different curvatures of the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb as shown in FIG. The longest width A2 of 601Y and 602Y must be wider than the width A of each spiral groove (A <A1), and the widths of the end portions 601Y and 602Y must be different from the groove width A of the spiral portion.

  The folding operation of the leg 92Y at the ends 601Y and 602Y of the spiral grooves 80Y and 81Y when the leg 92Y is configured by a plate-like member will be described with reference to FIG. In FIG. 13, points indicated by G and H indicate points where the outer walls 601Yb and 602Yb of the end portions 601Y and 602Y of the spiral grooves 80Y and 81Y are in contact with the leg portion 92Y. When the cross screw screw 60 rotates and the cross screw screw guide member 90Y moves, the plate-like leg portion 92Y enters the end portion 601Y serving as a turning portion while contacting the G point and the H point with the outer wall 601Yb, for example. Then, as shown in FIG. 13B, the end portion 601Y is bent while the point I of the plate-like leg portion 92Y facing the inner wall 601Ya of the end portion 601Y is in contact with the inner wall 601Ya. When the direction of the leg portion 92Y is changed, as shown in FIG. 13C, the end portion (folded portion) 601Y is bent while the point G and the point H are in contact with the outer wall 601Yb. The guide member 90Y (reflection density sensor 58Y) can perform a folding operation without decelerating. Note that when the leg portion 92Y passes through the end portion (folded portion) 602Y, the same movement as the end portion (folded portion) 601Y is performed.

  Since the plate-like leg portion 92Y moves in contact with the inner walls 601Ya and 602Ya and the outer walls 601Yb and 602Yb in this way, the way of contacting the cross screw screw guide member 90Y and the spiral grooves 80Y and 81Y is shown in FIG. As shown, if the support method is such that the bottom surface 92Ya of the leg portion 92Y and the bottom surfaces 80Ya and 81Ya of the spiral grooves 80Y and 81Y are in contact, the cross screw screw guide member 90Y can be moved continuously without falling. If the width R of the cylindrical main body 91Y is longer than the longest width A2 (R> A2), the main body 91Y is supported by the cross screw 60 as shown in FIG. The screw guide member 90Y can be continuously moved without overturning.

  As the shape of the bottom surface 92Ya of the plate-like leg portion 92Y, as shown in FIG. 7A, in addition to a rectangular shape with a width M <length D, it is shown in FIGS. 14A to 14D. Shape is conceivable. 14A is a rhombus shape whose diagonal is long in the traveling direction, FIG. 14B is a parallelogram shape long in the traveling direction, and FIG. 14C is an ellipse whose bottom shape is long in the traveling direction. FIG. 14D is an ellipse shape that is long in the traveling direction, and FIG. 14E is an ellipse whose bottom surface shape is shortened in the traveling direction. It is a shape, and the shape whose ellipse major axis is shorter than the width A of the spiral groove is shown. Also in each bottom-shaped leg portion 92Y, the shape of the end portions 601Y and 602Y as shown in FIG. 10B is the same as described above, and the folding operation can be performed without decelerating at the end portions 601Y and 602Y. .

  Next, the shape of the leg portion 92Y of the cross screw screw guide member 90Y will be described with respect to a shape in which a plurality of cylindrical pins having a circular bottom surface are provided as shown in FIG. In the form shown in FIG. 7 (d), the shape of the bottom surface is circular and three cylindrical pins are provided, but the number of pins is not limited to three. In this embodiment, the plurality of cylindrical pins are arranged in a straight line, and the cylindrical pins at the center thereof can be freely moved, so that the shapes of the end portions 601Y and 602Y of the spiral grooves 80Y and 81Y are formed. When the leg portion 92Y passes through the end portions 601Y and 602Y, the folding operation can be performed without decelerating.

  FIG. 15A is a view of the cross screw screw guide member 90Y viewed from the bottom surface 91Ya of the main body 91Y. Here, the three pins constituting the leg portion 92Y are referred to as pins B, C, and D for convenience. The pin B is positioned on the traveling direction side of the cross screw screw guide member 90Y (reflection density sensor 58Y), the pin C is positioned rearward in the traveling direction, and the pin D is positioned between the pins B and C. These pins are arranged on a straight line G passing through the center of the cylindrical main body 91Y, and are arranged at equal intervals in the traveling direction. The pin D located at the center is configured to be able to move freely so as to deviate from the straight line G. When the direction in which the straight line G extends is the traveling direction, the pin D is configured to be movable in a direction intersecting with the same plane. Specifically, the spiral grooves 80Y and 81Y are configured to be movable in the width A direction.

  As shown in FIGS. 15 (b), 15 (c), and 15 (d), the pins B and C move in the same manner as the pins E and F shown in FIGS. 12 (a) to 12 (c). do. Since the pin D is configured to be movable so as to deviate from the straight line G connecting the pins B, C, and D, as shown in FIG. 15C, the leg portion 92Y is moved to the end portion 601Y and the end portion 601Y2. When entering, the pin B and D move in the width direction by the inner wall 601Ya and the inner wall 602Ya. For this reason, when the cross screw 60Y is rotating, the pins B, C, and D always engage with the spiral grooves 80Y and 81Y, and end portions 601Y that are turned back without being disengaged from the spiral grooves 80Y and 81Y. And the end 602Y can be bent without decelerating.

  FIG. 16 shows a modification of the image carrier surface state detection device 200Y. The ends of the spiral grooves 80Y and 81Y formed on the cross screw 60Y used in the image carrier surface state detection device 200Y are arranged in a photosensitive member axial direction a as shown in FIGS. 16 (a) and 16 (b). Instead, they are continuous with each other by grooves 603Y and 604YY formed on the surface of the cross screw 60Y in the circumferential direction intersecting the axial direction. Each groove 603Y, 604YY is a groove formed linearly in the circumferential direction, and constitutes an end of the spiral grooves 80Y, 81Y.

  When the end portions of the forward and backward spiral grooves 80Y and 81Y are connected by linear grooves 603Y and 604YY formed continuously in the circumferential direction as in this embodiment, the cross screw screw 60 is When rotated, the leg 92Y moves in the forward spiral groove 80Y in the photosensitive member axial direction a and is guided to the groove 603Y. Then, when the groove 603Y is moved in the circumferential direction and rotated to a position facing the end of the backward moving spiral groove 81Y, the groove 603Y enters the spiral groove 81Y and moves in the spiral groove 81Y. Therefore, the reflection density sensor 58Y can be turned back without being decelerated when the reflection screw sensor 58Y rotates in the photosensitive body axial direction a by rotating the cross screw 60 and passes through the end portions 603Y and 604YY.

  However, in the case of this embodiment, a spiral groove is formed when the leg 92Y moves from the forward spiral groove 80Y to the backward spiral groove 81Y with respect to the shapes of the end portions 601Y and 602Y shown in FIG. The reflection density sensor 58Y is not guided to the backward spiral groove 81Y unless the cross screw 60 is rotated to a position where the backward spiral groove 81Y and the leg 92Y face each other. For this reason, when the reflection density sensor 58Y moves from the forward spiral groove 80Y to the backward spiral groove 81Y, the reflection density sensor 58Y moves in the circumferential direction. During this time, the reflection density sensor 58Y moves in the photosensitive body axial direction (axial direction). Since it cannot move, switching takes time compared with the case of edge part 601Y, 602Y shown in FIG. On the other hand, since the end portions 601Y and 602Y are curved in the axial direction of the cross screw screw 60, the processing is difficult. In this embodiment, the annular grooves 603Y and 604YY are formed on the surface of the cross screw screw 60. Since it should just be formed so that it may connect with the edge part of a spiral groove, it becomes the thing excellent in the surface of workability.

  By the way, when detecting the abnormal part by reciprocating the reflection density sensor 58Y in the photosensitive body axial direction a with the cross screw 60Y, if there is no positional information of the reflection density sensor 58Y, the normal part and the abnormal part on the photoreceptor 1Y are detected. I do not know the position. For this reason, in this embodiment, the angle detection means 71Y such as a rotary encoder is provided, and the detection plate 65Y is installed on the cross screw 60Y. From this information, the reflection density sensor 58Y on the photoreceptor 1Y is detected. By detecting the position, it is possible to detect the positions of the normal part and the abnormal part on the photoreceptor 1Y.

  As another form of the method for detecting the position of the normal part and the abnormal part on the photoconductor 1Y, as shown in FIG. 17, a detection toner image (detection pattern) S1 is formed at the end of the image forming area of the photoconductor 1Y. Image. The detection toner image S1 may be formed immediately after the image forming apparatus main body is activated or may be formed every predetermined number of sheets of the recording paper P. The image forming position of the detection toner image S1 is determined, and when the reflection density sensor 58Y detects this pattern, it can be seen that the reflection density sensor 58Y is positioned on this pattern. Further, since the rotational speed of the cross screw 60Y is determined by the rotational speed of the main body side drive source 41 (motor), the moving speed of the reflection density sensor 58Y is also naturally obtained. Therefore, a toner image for detection by the reflection density sensor 58Y is obtained. (Detection pattern) Even if the position of the reflection density sensor 58Y is detected from the detection information of S1 and the rotation speed of the main body side drive source 41 (motor), the positions of the normal part and the abnormal part on the photoreceptor 1Y are detected. can do.

  The manner of movement of the present invention and the conventional reflection density sensor will be described with reference to FIG. FIG. 18 is a diagram schematically illustrating how the sensor moves within the measurement time. In the figure, a curve X1 shows a movement locus of a conventional sensor that moves on the photosensitive member, and a curve X2 shows a movement locus of the reflection density sensor 58Y that moves on the photosensitive member by a moving means using a cross screw 60Y. . In FIG. 18, both the measurement time and the diameter of the photosensitive member are the same. Dotted lines Z1 and Z2 indicate the positions of the center points in the photosensitive member axial direction a. In the conventional configuration, the sensor can pass five times on the dotted line Z1, whereas in the configuration of the present invention, the sensor can pass seven times on the dotted line Z2. That is, it is possible to detect the surface state of the photoconductor more than before.

  For example, in the case of the embodiment shown in FIG. 4, the moving means of the reflection density sensor 58Y is a cross screw screw 60Y in which a forward spiral groove 80Y and a backward spiral groove 81Y intersect each other. The relationship between the leg portions 92Y of the cross screw screw guide member 90Y and the spiral grooves 80Y, 81Y that end portions 601Y, 602Y of 80Y, 81Y are curved in the photoconductor axial direction a and continue in an arc shape and support the reflection density sensor 58Y. However, when the cross screw 60Y rotates and the reflection density sensor 58Y moves between the forward spiral groove 80Y and the backward spiral groove 81Y, both of the spiral grooves 60Y rotate. Since the ends are continuous, there is no need to change the rotational direction of the cross screw 60Y. Further, at the time of switching between the forward spiral groove 80Y and the backward spiral groove 81Y used for the movement of the reflection density sensor 58Y, the rotational speed of the main body side drive source 41, which is the movement speed of the reflection density sensor 58Y, is reduced. There is no need. For this reason, since the moving distance of the reflection density sensor 58Y per unit time in the photosensitive body axial direction a is improved, the number of times that the reflection density sensor 58Y passes over the center point Z2, which is a specific point, per unit time is increased. it can. For this reason, if the center point Z2 is the detection position of the reflection density sensor 58Y, the number of detections in the photosensitive body axial direction a can be increased, and the state of the surface of the photoreceptor by the reflection density sensor 58Y can be measured more accurately. it can.

  On the other hand, in the conventional configuration, since there is one forward and backward spiral groove, it is necessary to switch the rotation direction of the drive motor when reciprocating the sensor in the photosensitive member axial direction a. In order to reduce the shock at the time of sensor overrun and motor rotation direction switching, it is necessary to decelerate.

Next, the reflection density sensor 58Y and the quality determination of the state of the photoreceptor surface based on the detection result of the reflection density sensor 58Y will be described.
In general, in a printer, in order to always obtain a stable image density, a detection toner image S1 such as a toner patch or a toner pattern is created on the surface of each photoconductor, and the toner adhesion amount of the detection toner image S1 (Toner density) is detected by a toner adhesion amount detection means, and the developer density and image density are appropriately controlled based on the detection result.

  As such a toner adhesion amount (toner concentration) detecting means, one that optically detects using a light emitting element and a light receiving element is known. For example, a light emitting diode (LED) is used as the light emitting element, and the light receiving element is used as the light receiving element. A reflection type photosensor combining PD (photodiode) or PTr (phototransistor) is generally used. The reflection type photosensor is configured to detect only regular reflection light from the detection toner image S1 as shown in FIG. 19A, and for detection as shown in FIG. 19B. There are a type that detects only diffuse reflected light from the toner image S1, a type that detects both as shown in FIG. 19A to 19C, reference numerals 101A, 101B, and 101C denote element holders, 102 denotes an LED, 103 denotes a regular reflection light receiving element, 1 denotes a photoconductor, and S1 denotes an image carrier. Reference numeral 104 denotes a detection toner image (toner patch or toner pattern), and reference numeral 104 denotes a diffuse reflection light receiving element.

  Such a reflection type photosensor is appropriately selected depending on the type of toner used (black toner, color toner), the state of the background portion of the photoreceptor 1 used, and the like. For example, when the toner to be used is black toner and the difference in the reflectance of the regular reflection light with respect to the background portion of the photoreceptor 1 is large, the type that detects only the regular reflection light shown in FIG. In the case of toner, since the difference in reflectance of regular reflection light with respect to the background portion of the photoreceptor 1 is small, the detection accuracy is lowered. For this reason, in the case of color toner, the type that detects the diffusely reflected light shown in FIG. In order to support both black toner and color toner, the type that detects diffuse reflection light shown in FIG. 19B or more preferably both regular reflection light and diffuse reflection light shown in FIG. 19C is used. The type to detect is good. The reflection density sensor 58Y according to this embodiment is an optical sensor that detects the surface state of the photoreceptor 1Y based on a difference in the amount of incident light and reflected light, and employs the type shown in FIG.

  FIG. 20 is a diagram showing the relationship between the development potential and the toner adhesion amount on the photoreceptor 1. The development potential is “photoreceptor potential−development bias [V]. The circle in FIG. 20 is the measurement result, and there is a region where the development potential and the toner adhesion amount data have a linear relationship. In this linear region, 21 shows the relationship between the detected electromotive force of the optical reflection density sensor 58Y used in this embodiment and the toner adhesion amount on the photosensitive member 1. When the toner adhesion amount on the photosensitive member 1 increases, the detected electromotive force [V ] Decreases.

  The effect of the present invention is that, when cross screw screws 60 (Y, M, C, K) are used for each moving means, the amount of toner adhered to the entire area of each photoconductor can be measured, and the toner on each photoconductor If there is an abnormality in the amount of adhesion, it is possible to detect the abnormal part.

  For example, the detection size (detection region) of the reflection density sensor 58Y is within a circle with a diameter of 3 mm as shown in FIGS. 22A and 22B, and the reflection density sensor 58Y is within a circle with a diameter of 3 mm. The toner adhesion amount on the photosensitive member 1 is detected. This circle having a diameter of 3 mm is defined as a light spot 96. The same applies to the other reflection density sensors 58 (M, C, K).

  The light spot 96 emitted from the reflection density sensor 58Y detects the toner image S1 developed on the photoreceptor 1Y while moving in the photoreceptor axial direction a. From the input text data and the number of pixels, the ratio of the toner in the light spot 96 and the ratio of the toner not adhering can be known. Since the relationship between the toner adhesion amount on the photoreceptor 1 and the detection electromotive force of the reflection density sensor 58Y is known from FIG. 21, the ratio of the area where the toner in the light spot 96 is adhered to the detection occurrence of the reflection density sensor 58Y. A relationship with electric power is required.

  The inventor measured the detected electromotive force in advance while changing the toner adhesion area ratio in the light spot 96 with the light spot diameter of 3 mm using the reflection density sensor 58Y. The measurement results are shown in FIG.

  In this measurement, characters as shown in FIG. 24A were developed using black toner, and the detected electromotive force was measured by the reflection density sensor 58Y. As shown in FIG. 24A, the character “Rico” is developed in the light spot 96, and the ratio of the toner adhering and the ratio of no toner adhering is 7: 3. The detected electromotive force of the reflection density sensor 58Y at that time was 1.5 [V]. According to FIG. 23, the detected electromotive force of the reflection density sensor 58Y when the area ratio is 70% is 1.5 [V], and the difference is 0 [V]. When such a difference does not occur, it can be determined that the input data is normally developed on the photoreceptor 1Y.

  FIG. 24B shows a state where white stripes 97 are generated. Here, the characters “c” and “o” of “Rico” are not correctly developed in the light spot 96. At this time, the electromotive force of the reflection density sensor 58Y was 2.5 [V]. Originally, the area ratio where the toner in the light spot 96 adheres is 70%, so the detected electromotive force should be detected at 1.5 [V], but the difference from the actually measured detected electromotive force is 1.0. [V] produced.

  In the present embodiment, the detected electromotive force is set in advance from the data input in this way, and the difference from the detected detected electromotive force is seen. If the difference is 0, it can be determined normal, and if there is a difference, it can be determined abnormal. That is, if there is no abnormal image, as shown in FIG. 25, the difference in detected electromotive force is always 0 [V] with respect to time, but if there is an abnormality, the detected electromotive force is periodically 0 [V]. Is not. At this time, it can be determined to be abnormal.

  In this embodiment, the difference in the detected electromotive force from the reflection density sensor 58Y is calculated by the control means 99 to which the reflection density sensor 58Y shown in FIG. 2 is connected, and the quality of the surface of the photoreceptor is determined according to the difference information. can do. The determination of the quality of the surface of the photoconductor is not performed only for the yellow photoconductor 1Y, and the other photoconductors 1M, 1C, and 1K are also provided with a reflection density sensor 58M that faces each photoconductor. , 58C, 58K, the control means 99 determines from the difference of the detected electromotive force. Further, since the position of each reflection density sensor on the photosensitive member is also determined by this control means 99, the normality of the surface of each photosensitive member is determined from the difference between each detected electromotive force and the position information of the reflection density sensor 58 on the photosensitive member. The surface state of the part and the abnormal part can be detected more accurately and at a lower cost than before.

  In the above embodiment, the detection means for detecting the surface state of each photoconductor is an optical sensor that detects the surface state of each photoconductor based on the difference in the amount of incident light and reflected light. It is not limited to a typical sensor. For example, the quality of the surface state of each photoconductor may be determined using a contact detection sensor that detects the surface state of the photoconductor by detecting the contact pressure with the surface of each photoconductor and displacing the contact pressure.

1 (Y, M, C, K) Image carrier 41 (Y, M, C, K) Driving means 58 (Y, M, C, K) Detection means 56 (Y, M, C, K) Moving means 60 (Y, M, C, K) Feed member 70 (Y, M, C, K) Cleaning member 71 (Y, M, C, K) Angle detection means 80 (Y, M, C, K) Forward spiral Guide part 81 (Y, M, C, K) Helical guide part 90, 93 (Y, M, C, K) for return movement Engagement part 92 (Y, M, C, K) Leg part 200 (Y, M, C, K) Image carrier surface state detection device 581 (Y, M, C, K) Detection surface of detection means 601Y, 602Y (Y, M, C, K) Guide portion end portion 603Y, 604YY (Y, M, C, K) End of guide part a Image carrier axial direction A Guide part width D Length of leg part relative to moving direction J1 Length of leg part in protruding direction Width N, N1 imaged region of the arbitrary point S1 detecting toner image W image bearing member depth M leg of the second guide portion

JP-A-5-281818

Claims (13)

Detecting means for detecting the surface state of the image carrier that is endless and moves its surface by rotating;
A moving unit that supports the detecting unit and reciprocates the detecting unit in the axial direction of the image carrier perpendicular to the surface movement direction of the image carrier;
The moving means includes forward and backward spiral guide portions extending in the axial direction of the image carrier, and ends of the forward and backward spiral guide portions are continuous with each other. A feed member, and drive means for rotationally driving the feed member in one direction,
The image carrier surface state detection device, wherein the detection means includes an engagement portion that engages with the guide portion. In the image carrier surface state detection device according to claim 1,
An image carrier surface state detection device, wherein an end of the forward and backward spiral guide portions is a switching portion curved in the axial direction of the image carrier. In the image carrier surface state detection device according to claim 1 or 2,
The engaging portion is a plurality of pins having a circular bottom surface in which the relationship between the length in the moving direction of the detecting means and the width in the direction intersecting the same plane in the same plane is width <length. Having a configured leg,
The end of the spiral guide part has an arc shape centered on an arbitrary point when the surface of the feed member is developed,
The image carrier surface, wherein a length of the leg portion constituted by the plurality of pins in a protruding direction with respect to the spiral guide portion is longer than a depth of the spiral guide portion. Condition detection device. In the image carrier surface state detection device according to claim 3,
The image bearing member surface state detection device according to claim 1, wherein the leg has an elliptical bottom shape, and the major axis of the ellipse is set to be shorter than the width of the spiral guide. In the image carrier surface state detection device according to claim 1 or 2,
The engaging portion has a relation between the length in the moving direction of the detecting means and the width in a direction intersecting the length in the same plane with the width <length, and enters the spiral guide portion. Legs to
The end portion of the spiral guide portion has an arc shape centered at an arbitrary point when the surface of the feed member is developed, and the width of the end portion of the arc shape is a guide portion other than the end portion. An image carrier surface state detection device characterized by being formed wider than the width of the image carrier. In the image carrier surface state detection device according to claim 5,
The width of the arc-shaped end is formed so that any two points of the leg are in contact with each other. In the image carrier surface state detection device according to any one of claims 1 to 6,
The image carrier surface state detection device, wherein the feeding member extends to the outside of the image forming area of the image carrier. In the image carrier surface state detection device according to any one of claims 1 to 7,
An image carrier surface state detection device comprising a cleaning member for cleaning a detection surface of the detection means on one side or both sides of the feeding member located in a non-image forming region of the image carrier. In the image carrier surface state detection device according to any one of claims 1 to 8,
An image carrier surface state detection device comprising angle detection means for detecting a rotation angle of the feeding member. In the image carrier surface state detection device according to any one of claims 1 to 8,
An image carrier surface state detection device, wherein the detection means detects a detection toner image formed at an end of an image forming area of the image carrier every predetermined time or a predetermined number of prints. In the image carrier surface state detection device according to any one of claims 1 to 10,
The image carrier surface state detection apparatus, wherein the detection means is an optical sensor that detects the surface state of the image carrier based on a difference in the amount of incident light. In the image carrier surface state detection device according to any one of claims 1 to 10,
The image carrier surface state detection device, wherein the detection means is a contact detection sensor that detects a surface state of the image carrier by displacement of a contact pressure with the surface of the image carrier.   An image forming apparatus comprising the image carrier surface state detection device according to claim 1.

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