JP5954580B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image using toner.

  An image forming apparatus generally includes a photosensitive drum and a charging device, an exposure device, a developing device, and the like disposed around the photosensitive drum. The surface of the photosensitive drum is uniformly charged by a charging device, and the charged portion is exposed by laser light emitted from the exposure device. As a result, an electrostatic latent image is formed on the photosensitive drum, and the electrostatic latent image is developed by the developing device to become a toner image.

  The toner image on the photosensitive drum is transferred to the paper that has been transported by the transport belt. The sheet on which the toner image is transferred is peeled off from the conveyance belt and conveyed to the fixing device, where the toner is fixed and discharged.

  The fixing device has a fixing belt for heating and pressurizing the paper.

  For example, in an image forming apparatus that can use A4 size paper and A3 size paper, if fixing of A4 size paper is repeated in the state of longitudinal paper, the end of the A4 size paper on the surface of the fixing belt in the paper width direction passes. Vertical streak may occur at the position. This is caused by the surface of the fixing belt being roughened by paper dust at the end of the paper.

  At this time, when A4 landscape paper or A3 portrait paper is made, so-called glossy streaks appear on the image surface corresponding to the vertical streak and the image quality deteriorates.

  In view of this, an image forming apparatus that takes into consideration the roughness of the fixing belt surface has been devised (see, for example, Patent Documents 1 to 4).

  The demand for image quality in image forming apparatuses is increasing year by year. However, in the image forming apparatuses disclosed in Patent Documents 1 to 4, it has been difficult to obtain a required level of image quality.

  The present invention relates to an image forming apparatus having a fixing member for fixing an image on a recording medium moving in a first axis direction, wherein a plurality of lights are emitted toward the fixing member and orthogonal to the first axis direction. A plurality of light spots having a predetermined pitch with respect to the second axis direction are formed on the surface of the fixing member, and the reflection type optical sensor that receives the light reflected by the fixing member and the reflection type optical sensor are arranged on the second axis. And a processing device for determining the surface state of the fixing member based on output signals of the reflective optical sensor when the reflective optical sensor is in a plurality of positions different from each other with respect to the second axis direction. And an image forming apparatus.

  According to the image forming apparatus of the present invention, a good image can be formed.

1 is a diagram for describing a schematic configuration of a color printer according to an embodiment of the present invention. FIG. It is a figure for demonstrating an image forming unit. It is a figure for demonstrating a fixing device. It is a figure for demonstrating the arrangement position of a reflection type optical sensor. It is FIG. (1) for demonstrating a reflection type optical sensor. It is FIG. (2) for demonstrating a reflection type optical sensor. It is FIG. (3) for demonstrating a reflection type optical sensor. It is FIG. (4) for demonstrating a reflection type optical sensor. It is a figure for demonstrating a drive mechanism. FIG. 3 is a first diagram for explaining the configuration of a drive mechanism; It is AA sectional drawing of FIG. FIG. 8 is a second diagram for explaining the configuration of the drive mechanism; FIG. 13A is a diagram for explaining the A state, and FIG. 13B is a diagram for explaining the B state. It is a figure for demonstrating the irradiation position on the fixing belt surface of the light inject | emitted from each light emission part in the A state. It is a figure for demonstrating the irradiation position on the fixing belt surface of the light inject | emitted from each light emission part in the B state. It is a figure for demonstrating C state. It is FIG. (1) for demonstrating a comparative example. It is FIG. (2) for demonstrating a comparative example. FIG. 19A and FIG. 19B are diagrams for explaining the advantages of the reflective optical sensor of this embodiment. FIG. 20A is a diagram for explaining the method 1, and FIG. 20B is a diagram for explaining the method 2. It is a figure for demonstrating the modification of a drive mechanism. It is AA sectional drawing of FIG. FIG. 23A and FIG. 23B are diagrams for explaining modifications of the reflective optical sensor, respectively. It is a figure for demonstrating the surface state check process 1 by the reflective optical sensor of a modification. It is a figure for demonstrating the outgoing angle characteristic of reflected light. It is a figure for demonstrating the relationship between the arrangement position of the several light-receiving part regarding a y-axis direction, and the output angle characteristic of reflected light. It is a figure for demonstrating the arrangement position of the several light-receiving part regarding the y-axis direction in the reflective optical sensor of a modification. It is a figure for demonstrating the surface state check process 2 by the reflection type optical sensor of a modification. It is a figure for demonstrating the case where two reflective optical sensors are provided.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 according to an embodiment.

  The color printer 2000 is a tandem multi-color printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes an optical scanning device 2010, four photosensitive drums (2030a, 2030b, 2030c, 2030d), four image forming units (2034a, 2034b, 2034c, 2034d), intermediate transfer belt 2040, secondary transfer roller 2042, fixing device 2050, paper feed roller 2054, paper discharge roller 2058, paper feed tray. 2060, a paper discharge tray 2070, a communication control device 2080, a reflection type optical sensor 2245, a drive mechanism 100, an operation panel (not shown), and a printer control device 2090 that controls the above-described units centrally.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 2090 includes a CPU, a program described in a code decodable by the CPU, a ROM storing various data used when executing the program, a RAM that is a working memory, an amplification circuit And an A / D conversion circuit for converting analog data into digital data. Then, the printer control device 2090 notifies the optical scanning device 2010 of multi-color image information (black image information, cyan image information, magenta image information, yellow image information) received from the host device via the communication control device 2080. To do.

  The operation panel has a plurality of keys for the operator to make various settings and a display for displaying various information.

  The photosensitive drum 2030a and the image forming unit 2034a are used as a set, and constitute an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image.

  The photosensitive drum 2030b and the image forming unit 2034b are used as a set, and constitute an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image.

  The photosensitive drum 2030c and the image forming unit 2034c are used as a set, and constitute an image forming station (hereinafter also referred to as “C station” for convenience) for forming a cyan image.

  The photosensitive drum 2030d and the image forming unit 2034d are used as a set, and constitute an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. Here, the surface of each photosensitive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  As shown in FIG. 2 as an example, each image forming unit has a charging unit, a developing unit, a primary transfer unit, and a photoconductor cleaning unit provided around the corresponding photoconductor drum.

  Here, a contact charging type charging roller is used as the charging unit. The charging roller uniformly charges the surface of the photosensitive drum by applying a voltage in contact with the photosensitive drum. As the charging unit, a non-contact charging type such as a non-contact scorotron charger can also be used.

  In the developing unit, a two-component developer composed of a magnetic carrier and a nonmagnetic toner is used. The developing unit can be roughly divided into a stirring unit and a developing unit provided in the developing case.

  In the agitation unit, the two-component developer is conveyed while being agitated and supplied onto a developing sleeve as a developer carrying member. The stirring unit has two parallel screws, and a partition plate is provided between the two screws to partition the two screws so as to communicate with each other. Further, a TC sensor for detecting the toner concentration of the developer in the developing unit is attached to the developing case. Since the carrier of the two-component developer is a magnetic material, and the toner is a non-magnetic material, a TC sensor of the magnetic permeability type is used, and the toner concentration in the developing unit is the magnetic permeability of the developer, that is, the unit. Appears in the magnetic resistance of the developer per volume. Note that a one-component developer can also be used as the developer.

  In the developing unit, toner in the developer adhering to the developing sleeve is transferred to the photosensitive drum. The developing unit includes a developing sleeve that faces the photosensitive drum through the opening of the developing case, and a doctor blade that is disposed so that the tip approaches the developing sleeve. A magnet (not shown) is fixedly arranged in the developing sleeve.

  Therefore, in the developing unit, the developer is conveyed and circulated while being stirred by two screws, and is supplied to the developing sleeve. The developer supplied to the developing sleeve is pumped up and held by a magnet. The developer pumped up by the developing sleeve is conveyed along with the rotation of the developing sleeve and is regulated to an appropriate amount by the doctor blade. Excess developer is returned to the stirring section.

  The developer transported to the developing area facing the photosensitive drum in this manner is brought into a spiked state by the magnet and forms a magnetic brush. In the development region, a development electric field that moves the toner in the developer to the electrostatic latent image portion on the photosensitive drum is formed by the development bias applied to the development sleeve. As a result, the toner in the developer is transferred to the electrostatic latent image portion on the photosensitive drum, and the electrostatic latent image on the photosensitive drum is visualized.

  The developer that has passed through the development region is transported to a portion where the magnetic force of the magnet is weak, so that it is separated from the development sleeve and returned to the agitation unit. When the toner concentration in the stirring unit becomes light by repeating such operations, the TC sensor detects this, and toner is supplied to the stirring unit from a toner cartridge (not shown) based on the detection result.

  Further, the primary transfer unit is provided at a position facing the corresponding photosensitive drum via the intermediate transfer belt 2040.

  Here, a primary transfer roller is used as the primary transfer unit. The primary transfer roller is installed so as to be pressed against the photosensitive drum with the intermediate transfer belt 2040 interposed therebetween. As the primary transfer unit, in addition to the roller-shaped unit, a conductive brush-shaped unit, a non-contact corona charger, or the like may be used.

  The photoconductor cleaning unit has a cleaning blade (for example, made of polyurethane rubber) arranged so that the tip is pressed against the photoconductor drum, and a conductive fur brush arranged in contact with the photoconductor drum. ing. A bias voltage is applied to the fur brush from a metal electric field roller (not shown), and a tip of a scraper (not shown) is pressed against the electric field roller. The toner removed from the photosensitive drum by the cleaning blade and the fur brush is accommodated in the photosensitive member cleaning unit and collected by a waste toner collecting unit (not shown).

  Returning to FIG. 1, the optical scanning device 2010 uses light modulated for each color based on multicolor image information (black image information, cyan image information, magenta image information, yellow image information) from the printer control device 2090. The surface of the corresponding charged photosensitive drum is scanned. Thereby, an electrostatic latent image corresponding to the image information is formed on the surface of each photosensitive drum. The electrostatic latent image formed here moves in the direction of the corresponding developing unit as the photosensitive drum rotates, and is visualized by the developing unit. Here, the toner-attached image (toner image) moves in the direction of the intermediate transfer belt 2040 as the photosensitive drum rotates.

  The yellow, magenta, cyan, and black toner images are sequentially transferred onto the intermediate transfer belt 2040 at a predetermined timing, and are superimposed to form a multicolor image.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060. The paper feed roller 2054 takes out the recording paper one by one from the paper feed tray 2060. The recording sheet is sent out toward the gap between the intermediate transfer belt 2040 and the secondary transfer roller 2042 at a predetermined timing. As a result, the toner image on the intermediate transfer belt 2040 is transferred to the recording paper. The recording sheet transferred here is sent to the fixing device 2050.

  In the fixing device 2050, heat and pressure are applied to the recording paper, thereby fixing the toner on the recording paper. Here, the recording paper on which the toner is fixed is sent to a paper discharge tray 2070 via a paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  The reflective optical sensor 2245 is disposed in the vicinity of the fixing device 2050. Details of the reflective optical sensor 2245 will be described later.

  The drive mechanism 100 moves the reflective optical sensor 2245. Details of the drive mechanism 100 will be described later.

  As shown in FIG. 3 as an example, the fixing device 2050 includes a pressure roller 501, a fixing belt 502, a fixing roller 503, a heating roller 504, a tension roller 505, and the like.

  The pressure roller 501 is formed by coating a metal core such as aluminum or iron with an elastic member such as silicone rubber and coating the surface with a fluororesin.

  The fixing belt 502 is made of nickel, polyimide, or the like as a base material and has a surface coated with a fluororesin. An elastic member such as silicone rubber may be added between the base material and the fluororesin.

  The fixing belt 502 is wound around a fixing roller 503, a heating roller 504, and a tension roller 505, and is maintained at an appropriate tension by the tension roller 505.

  The fixing roller 503 is formed by coating a metal core such as aluminum or iron with silicone rubber.

  The heating roller has a heat source such as an aluminum or iron hollow roller and a halogen heater provided inside the hollow roller.

  In the fixing device 2050, when the recording paper enters the nip portion formed by the fixing roller 503 and the pressure roller 501, a predetermined pressure and heat are applied to the recording paper in the nip portion, and the toner image on the recording paper. Is established.

  When the fixing of the A4 size recording paper is repeated in the state of the longitudinal paper in the fixing device 2050, a vertical streak is generated at a position where the end of the recording paper in the width direction passes on the surface of the fixing belt 502. Sometimes. This occurs when the surface of the fixing belt 502 is roughened by paper dust at the end of the recording paper.

  At this time, if the recording paper is A4 landscape paper or A3 portrait paper, so-called gloss streaks appear on the surface of the image corresponding to the scratches, and the image quality deteriorates.

  Therefore, in order to know the state of the scratch (scratch density) on the fixing belt 502, a reflective optical sensor 2245 is disposed in the vicinity of the fixing device 2050.

Next, the reflective optical sensor 2245 will be described.
Here, in the xyz three-dimensional orthogonal coordinate system, the direction perpendicular to the belt surface of the fixing belt 502 between the heating roller 504 and the tension roller 505 is defined as the z-axis direction, and the moving direction of the belt surface is defined as the + x direction. To do. The reflective optical sensor 2245 is disposed on the + z side of the fixing device 2050 at a position facing the portion of the fixing belt 502 where the scratch is generated (see FIG. 4).

  The moving direction of the belt surface in the fixing belt 502 is referred to as a “sub direction”, and the direction orthogonal to the sub direction on the belt surface (here, the y-axis direction) is referred to as a “main direction”.

  As an example, as shown in FIGS. 5 to 8, the reflective optical sensor 2245 includes an illumination system including ten light emitting units (E1 to E10) and illumination including ten illumination microlenses (LE1 to LE10). An optical system, a light receiving optical system including twelve light receiving microlenses (LD0 to LD11), a light receiving system including twelve light receiving portions (D0 to D11), and the like are provided.

The ten light emitting units (E1 to E10) are arranged at equal intervals (inter-center distance) Le along the y-axis direction. For each light emitting unit, an LED (Light Emitting Diode) can be used. Here, as an example, Le = 0.6 mm. The wavelength of light emitted from each light emitting unit is 850 nm. Hereinafter, for convenience, the light emitting unit that is turned on is also referred to as a “lighting light emitting unit”.
Each light emitting unit is individually turned on and off individually according to an instruction from the printer control device 2090.

  The ten illumination microlenses (LE1 to LE10) are arranged at equal intervals (distance between the centers) along the y-axis direction, and individually correspond to the ten light emitting units (E1 to E10).

  Each illumination microlens condenses and guides light emitted from the corresponding light emitting unit toward the surface of the fixing belt 502. In each illumination microlens, the lens diameter, the radius of curvature of the lens, and the lens thickness are the same. In addition, the optical axis of each illumination microlens is parallel to a direction (here, the z-axis direction) orthogonal to the light emission surface of the corresponding light emitting unit.

Here, for easy understanding, only the light emitted from each light emitting portion and passing through the corresponding illumination microlens illuminates the fixing belt 502 as detection light (S1 to S10), and the surface of the fixing belt 502 It is assumed that the detection light spots (SP1 to SP10) are formed on (see FIG. 7).
As an example, the size (diameter) of each detection light spot is about 0.6 mm.

  In the following description, when it is not necessary to specify the light emitting part, an integer i of 1 to 10 is used and expressed as “light emitting part Ei” in order to avoid complexity. The illumination microlens corresponding to the light emitting unit Ei is denoted as “illumination microlens LEi”. The light emitted from the light emitting unit Ei and passing through the illumination microlens LEi is referred to as “detection light Si”.

  A light spot formed on the surface of the fixing belt 502 by the detection light Si is referred to as “detection light spot SPi”.

  The twelve light receiving parts (D0 to D11) are arranged at equal intervals (inter-center distance) along the y-axis direction.

  The light emitted from the light emitting unit E1 and reflected by the surface of the fixing belt 502 is set so as to be received by the light receiving unit D0, the light receiving unit D1, and the light receiving unit D2.

  The light emitted from the light emitting unit E2 and reflected by the surface of the fixing belt 502 is set so as to be received by the light receiving unit D1, the light receiving unit D2, and the light receiving unit D3.

  The light emitted from the light emitting unit E3 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D2, the light receiving unit D3, and the light receiving unit D4.

  The light emitted from the light emitting unit E4 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D3, the light receiving unit D4, and the light receiving unit D5.

  The light emitted from the light emitting unit E5 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D4, the light receiving unit D5, and the light receiving unit D6.

  The light emitted from the light emitting unit E6 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D5, the light receiving unit D6, and the light receiving unit D7.

  The light emitted from the light emitting unit E7 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D6, the light receiving unit D7, and the light receiving unit D8.

  The light emitted from the light emitting unit E8 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D7, the light receiving unit D8, and the light receiving unit D9.

  The light emitted from the light emitting unit E9 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D8, the light receiving unit D9, and the light receiving unit D10.

  The light emitted from the light emitting unit E10 and reflected by the surface of the fixing belt 502 is set to be received by the light receiving unit D9, the light receiving unit D10, and the light receiving unit D11.

  Therefore, the three light receiving units that receive light emitted from the light emitting unit Ei and reflected from the surface of the fixing belt 502 are denoted as a light receiving unit D (i−1), a light receiving unit Di, and a light receiving unit D (i + 1). . These three light receiving parts (D (i−1), Di, D (i + 1)) are also referred to as light receiving parts corresponding to the light emitting part Ei.

  A PD (photodiode) can be used for each light receiving portion. Each light receiving unit outputs a signal corresponding to the amount of received light. The output signal of each light receiving unit is sent to the printer control device 2090.

  The twelve light receiving microlenses (LD0 to LD11) individually correspond to the twelve light receiving portions (D0 to D11), respectively, and collect the light reflected by the surface of the fixing belt 502. In this case, the amount of light received by each light receiving unit can be increased. That is, detection sensitivity can be improved. In each light receiving microlens, the lens diameter, the radius of curvature of the lens, and the lens thickness are the same.

  Each microlens has a spherical lens having a condensing function in the x-axis direction and the y-axis direction, a cylindrical lens having a positive power in the x-axis direction, and a power in the x-axis direction and a power in the y-axis direction are different from each other. An anamorphic lens or the like can be used.

  In the present embodiment, as an example, each microlens is a spherical lens. In each illumination microlens, the incident-side optical surface has condensing power, and the exit-side optical surface does not have condensing power. In each light receiving microlens, the exit-side optical surface has a condensing power, and the incident-side optical surface does not have a condensing power.

  Specifically, in each illumination microlens, the lens diameter is 0.415 mm, the radius of curvature of the lens is 0.430 mm, and the lens thickness is 1.229 mm. Each light-receiving microlens has a lens diameter of 0.712 mm, a lens radius of curvature of 0.380 mm, and a lens thickness of 1.419 mm.

  In this embodiment, 10 illumination microlenses (LE1 to LE10) and 12 light receiving microlenses (LD0 to LD11) are integrated to form a microlens array. Thereby, workability | operativity at the time of assembling each micro lens in a predetermined position can be improved. Moreover, the positional accuracy between the lens surfaces in a plurality of microlenses can be increased. Each lens surface can be formed on a glass substrate or a resin substrate by using a processing method such as photolithography or injection molding.

Next, the drive mechanism 100 will be described.
As an example, as shown in FIG. 9, the drive mechanism 100 is disposed on the + z side of the reflective optical sensor 2245 and moves the reflective optical sensor 2245 along the y-axis direction according to an instruction from the printer control device 2090.

  As shown in FIGS. 10 to 12 as an example, the drive mechanism 100 includes a slider 101, a solenoid actuator 102, two springs (103, 104), two stoppers (105, 106), a base member 107, and the like. have. FIG. 11 is a cross-sectional view taken along the line AA in FIG. FIG. 12 is a view when the reflective optical sensor 2245 is removed from FIG.

  The slider 101 is a rectangular bar member whose longitudinal direction is the y-axis direction, and grooves extending in the y-axis direction are formed on both end faces in the x-axis direction. A reflective optical sensor 2245 is fixed to the + z side surface of the slider 101.

The spring 103 is disposed on the + y side of the slider 101 and biases the slider 101 with a force in the −y direction.
The spring 104 is disposed on the −y side of the slider 101 and biases the slider 101 with a force in the + y direction.

The stopper 105 is a member that restricts the movement of the slider 101 in the −y direction.
The stopper 106 is a member that restricts the movement of the slider 101 in the + y direction.

  For example, when the −y side end of the slider 101 is in contact with the stopper 106, the distance M in the y axis direction between the + y side end of the slider 101 and the stopper 105 is the maximum amount of movement of the slider 101. Of course, when the + y side end of the slider 101 is in contact with the stopper 105, the distance in the y-axis direction between the −y side end of the slider 101 and the stopper 106 is also M. In the present embodiment, as an example, M = Le.

  The base member 107 is a rectangular bar member whose longitudinal direction is the y-axis direction, and has two guide portions that are fitted in the two grooves of the slider 101. Note that a ball bearing for smooth movement of the slider 101 is provided between the slider 101 and the guide portion.

  The solenoid actuator 102 is driven and controlled by the printer controller 2090 and changes the force in the −y direction applied to the spring 103.

  Therefore, by driving the solenoid actuator 102, the reflective optical sensor 2245 can be moved in the y-axis direction (see FIGS. 13A and 13B). Hereinafter, for convenience, the state in which the reflective optical sensor 2245 is located closest to the −y side is also referred to as “A state”, and the state in which the reflective optical sensor 2245 is located closest to the + y side is referred to as “B state. "

  The base member 107 holds a solenoid actuator 102 and two stoppers (105, 106).

  By the way, in the reflective optical sensor 2245, the variation in the amount of light emitted from the ten light emitting units (E1 to E10), the variation in the optical characteristics of the ten illumination microlenses (LE1 to LE10), and the twelve Variations in the optical characteristics of the light receiving microlenses (LD0 to LD11) and variations in the light receiving sensitivity of the 12 light receiving portions (D0 to D11) can be considered.

  In this case, for example, even if the light emitted from the light emitting unit E1 and the light emitted from the light emitting unit E2 are irradiated to the same position on the fixing belt 502, three light receiving units (D0) corresponding to the light emitting unit E1. , D1, D2) and the total level of the output signals of the three light receiving sections (D1, D2, D3) corresponding to the light emitting section E2 (hereinafter also referred to as “summed level value”). The values are not necessarily the same.

  Therefore, a correction coefficient for correcting the variation is obtained in advance. The process for obtaining the correction coefficient (correction coefficient acquisition process) is performed by the printer control device 2090. This correction coefficient acquisition process will be described below.

  When the correction coefficient acquisition process is being performed, the fixing belt 502 may be rotating or may be stationary.

  A correction coefficient for correcting the total level value of the output signals of the light receiving units (D (i−1), Di, D (i + 1)) corresponding to the light emitting unit Ei is expressed as αi (i = 1 to 10). To do.

  In addition, when the reflective optical sensor 2245 is in the A state, the center of the position where the light emitted from the light emitting portion E1 is irradiated on the fixing belt 502 is c1, and the position where the light emitted from the light emitting portion E2 is irradiated. C2 is the center of the position where the light emitted from the light emitting part E3 is irradiated, c3 is the center of the position where the light emitted from the light emitting part E4 is irradiated, c4, and the light emitted from the light emitting part E5 is The center of the irradiated position is c5, the center of the position irradiated with the light emitted from the light emitting part E6 is c6, the center of the position irradiated with the light emitted from the light emitting part E7 is emitted from the light emitting part E8. The center of the position irradiated with the emitted light is c8, the center of the position irradiated with the light emitted from the light emitting unit E9 is c9, and the center of the position irradiated with the light emitted from the light emitting unit E10 is c10. (See FIG. 14).

  In addition, when the reflective optical sensor 2245 is in the B state, the center of the position where the light emitted from the light emitting portion E1 is irradiated on the fixing belt 502 is defined as c0 (see FIG. 15). Since M = Le, the centers of the positions on the fixing belt 502 where the light emitted from the light emitting portions E2 to E10 is irradiated are c1 to c9.

(1) The reflective optical sensor 2245 is set to the A state, and the ten light emitting units (E1 to E10) are sequentially turned on / off individually, and the summed level value of the output signal of the corresponding light receiving unit is determined for each lighting light emitting unit. get.
(2) The process (1) is performed a plurality of times.
(3) For each lighting light emitting unit, the average value or median value of the obtained plurality of combined level values, or the average value or median value of the plurality of combined level values excluding the abnormal value is obtained as a detection value.
Here, the detection value when the lighting light emitting unit is Ei is expressed as Vai (i = 1 to 10).
(4) The reflective optical sensor 2245 is set to the B state, and the ten light emitting units (E1 to E10) are sequentially turned on / off individually, and the total level value of the output signal of the corresponding light receiving unit is determined for each lighting light emitting unit. get.
(5) The process (4) is performed a plurality of times.
(6) For each lighting light emitting unit, the average value or median value of the obtained plurality of combined level values, or the average value or median value of the plurality of combined level values excluding the abnormal value is obtained as a detection value.
Here, the detection value when the lighting light emitting unit is Ei is expressed as Vbi (i = 1 to 10).

  (7) When the reflective optical sensor 2245 is in the A state, the center of the position where the light emitted from the light emitting portion E1 is irradiated on the fixing belt 502 is c1, and when the reflective optical sensor 2245 is in the B state. In addition, the center of the position where the light emitted from the light emitting portion E2 is irradiated on the fixing belt 502 is also c1. That is, if there is no variation, Va1 and Vb2 should be equal. Therefore, considering the above variation, (Va1 / Vb2) is calculated as a correction coefficient α2 for correcting the detection value when the lighting light emitting unit is E2.

  Here, Va1 that is a detection value when the reflective optical sensor 2245 is in the A state and the lighting light emitting unit is E1 is used as a reference. Therefore, the correction coefficient α1 is 1.

  (8) When the reflective optical sensor 2245 is in the A state, the center of the position where the light emitted from the light emitting portion E2 is irradiated on the fixing belt 502 is c2, and when the reflective optical sensor 2245 is in the B state. In addition, the center of the position where the light emitted from the light emitting portion E3 is irradiated on the fixing belt 502 is also c2. That is, if there is no variation, Va2 and Vb3 should be equal. Then, taking Va1 as a reference and taking into account the above variation, (Va2 / Vb3) × α2 is calculated as a correction coefficient α3 for correcting the detection value when the lighting light emitting unit is E3.

(9) When the reflective optical sensor 2245 is in the A state, the center of the position where the light emitted from the light emitting unit E3 is irradiated is c3 on the fixing belt 502, and when the reflective optical sensor 2245 is in the B state Further, the center of the position where the light emitted from the light emitting portion E4 is irradiated on the fixing belt 502 is also c3. That is, if there is no variation, Va3 and Vb4 should be equal. Then, taking Va1 as a reference and taking into account the above-described variation, (Va3 / Vb4) × α3 is calculated as a correction coefficient α4 for correcting the detection value when the lighting light emitting unit is E4.
Thereafter, similarly, correction coefficients α5 to α10 are calculated.

  The printer control device 2090 stores the correction coefficients α1 to α10 thus obtained in the ROM of the printer control device 2090. Then, the correction coefficient acquisition process ends.

Further, the printer control device 2090 prints a predetermined number (for example, 500 sheets) of A4 recording paper in the vertical state and then prints the A4 recording paper in the horizontal state or when printing the A3 recording paper. For example, the surface state of the fixing belt 502 is checked using the reflective optical sensor 2245. This surface state check process will be described below.
When the surface condition check process is being performed, the fixing belt 502 is rotating.

  Also, as shown in FIG. 16, the state in which the reflective optical sensor 2245 has moved from the A state to the + y side by M / 2 (here, the same as Le / 2) is referred to as “C state”.

  (A) The reflective optical sensor 2245 is set to the A state, and the ten light emitting units (E1 to E10) are sequentially turned on and off individually, and the summed level value of the output signal of the corresponding light receiving unit is set for each lighting light emitting unit. get.

(B) The process (a) is performed a plurality of times.
(C) For each lighting light emitting unit, the average value or median value of the obtained plurality of combined level values, or the average value or median value of the plurality of combined level values excluding the abnormal value is obtained as a detection value.

(D) For each lighting light emitting unit, the corresponding correction coefficient is multiplied by the obtained detection value to correct the variation.
Here, the corrected detection value when the lighting light emitting unit is Ei is expressed as Hai (i = 1 to 10).

(E) The reflective optical sensor 2245 is set to the C state, and the ten light emitting units (E1 to E10) are individually turned on / off individually, and the total level value of the output signal of the corresponding light receiving unit is determined for each lighting light emitting unit. get.
(F) The process of (e) is performed a plurality of times.

(G) For each lighting light emitting unit, the average value or median value of the obtained plurality of summed level values, or the average value or median value of the plurality of summed level values excluding the abnormal value is obtained as a detection value.
Here, the corrected detection value when the lighting light emitting unit is Ei is expressed as Hbi (i = 1 to 10).

  (H) The position of the scratch on the fixing belt 502 is obtained based on Hai (i = 1 to 10) and Hbi (i = 1 to 10).

  By the way, when the light emitted from the light emitting unit is applied to a portion having a flaw on the fixing belt 502, the detected value is lowered because the light is scattered by the flaw.

  Therefore, here, based on Hai (i = 1 to 10) and Hbi (i = 1 to 10), a position where the detection value is minimum is found, and that position is set as the position of the scratch.

  (I) The flaw density is obtained based on the decrease rate of the detected value at the flaw position. It should be noted that the relationship between the flaw density and the decrease rate of the detected value is obtained in advance through experiments or the like, and is stored in the ROM of the printer control device 2090.

  (J) The scratch position and the scratch density are stored in the RAM of the printer control device 2090. Then, the surface state check process ends.

  Then, the printer control device 2090 indicates that the surface of the fixing belt 502 is scratched on the display of the operation panel when the scratch density detected in the surface state check process exceeds a preset threshold value. In addition to the message, the position of the flaw and the flaw density are displayed. The operator notifies the maintenance company of the display content of the display. This information may be automatically notified from the color printer 2000 to the maintenance company via a public line.

The maintenance company performs processing so that the surface roughness of the fixing belt 502 becomes uniform according to the position where the scratch exists and the density of the scratch. In this case, since the flawed position and flaw density are obtained with high accuracy, it is possible to prevent the surface roughness of the fixing belt 502 from becoming uneven. That is, maintenance of the fixing belt 502 can be performed appropriately.
Therefore, the printer control device 2090 can stably form a good image.

Here, as a comparative example, as shown in FIG. 17 as an example, two reflection type optical sensors each having one light emitting element and one light receiving element are used, and as an example, as shown in FIG. Consider a case in which the base (sensor A) is disposed at a position facing the site of occurrence of the scratch and the other one (sensor B) is disposed at a position facing the site different from the site of occurrence of the wound.
In this comparative example, the output signal of the sensor A and the output signal of the sensor B are compared to determine the degree of scratches.

  By the way, the fixing belt 502 meanders for a few seconds after starting driving. Therefore, in the above comparative example, in the sensor A, there is a possibility that the light emitted from the light emitting element is irradiated to a position shifted from the generation site, and in this case, the degree of the scratch cannot be correctly determined.

  On the other hand, in the reflection-type optical sensor 2245 of this embodiment, for example, when the fixing belt 502 is meandering and in the A state, as shown in FIG. Even if it is located between the detection light spots SP6, in the C state, as shown in FIG. 19 (B), the wound site is located at the center of the detection light spot SP6. be able to.

  Further, as a first method of suppressing the occurrence of the scratched portion between the two detection light spots, as shown in FIG. 20A, the density of the detection light spots in the y-axis direction is shown. It is possible to increase the value. However, in this case, it is necessary to increase the number of light emitting units, which causes an inconvenience that the cost is increased.

  As a second method, as shown in FIG. 20B, it is conceivable to increase the spot diameter of the detection light spot. However, this case has a disadvantage that the detection sensitivity is lowered.

  As described above, according to the color printer 2000 according to the present embodiment, the optical scanning device 2010, the four image forming stations, the intermediate transfer belt 2040, the secondary transfer roller 2042, the fixing device 2050, the reflective optical sensor 2245, and the drive. A mechanism 100, a printer control device 2090, and the like are provided.

  The reflective optical sensors 2245 are arranged at equal intervals Le along the y-axis direction, and 10 light emitting units (E1 to E10) that emit light toward the fixing belt 502, and the light reflected by the fixing belt 502 12 light receiving portions (D0 to D11) and the like.

  The drive mechanism 100 includes a slider 101 to which the reflective optical sensor 2245 is fixed, a solenoid actuator 102 that moves the slider 101 along the y-axis direction with a maximum movement amount as M, and the like.

  The printer control device 2090 sequentially turns on and off the ten light emitting units (E1 to E10) individually when the reflective optical sensor 2245 is in the A state and when the reflective optical sensor 2245 is in the C state. For each lighting light emitting unit, the total level value of the output signal of the corresponding light receiving unit is obtained to obtain the detection value. Then, the printer control device 2090 corrects the obtained detection value, searches for the position of the flaw, and obtains the flaw density from the decrease rate of the detection value.

  In this case, even if the fixing belt 502 meanders, the position and the density of the scratch can be obtained with high accuracy. As a result, the fixing belt 502 can be properly maintained, and the color printer 2000 can stably form a good image.

  In the above embodiment, a piezoelectric actuator may be used instead of the solenoid actuator 102.

  In the above embodiment, instead of the drive mechanism 100, a drive mechanism 100 'having a motor and a ball screw may be used as shown in FIGS. 21 and 22 as an example. 22 is a cross-sectional view taken along the line AA in FIG.

  Moreover, although the said embodiment demonstrated the case where Le = 0.6 mm, it is not limited to this.

  In the above-described embodiment, the case of M = Le has been described. However, the present invention is not limited to this. That is, assuming that the number of light emitting units is N, it is sufficient that Le ≦ M ≦ (N−1) × Le.

For example, a correction coefficient acquisition process when M = 9 × Le will be described.
Here, the state in which the reflective optical sensor 2245 has moved by Le from the A state to the + y side is “P1 state”, and the state in which the reflective optical sensor 2245 has moved by 2 × Le from the A state to the + y side is “P2 state”. The state in which the reflective optical sensor 2245 has moved 3 × Le from the A state to the + y side is “P3 state”, and the state in which the reflective optical sensor 2245 has moved 4 × Le from the A state to the + y side is “P4 state”. The state in which the reflective optical sensor 2245 has moved 5 × Le from the A state to + y side is “P5 state”, and the state in which the reflective optical sensor 2245 has moved 6 × Le from the A state to + y side is “P6 state”. The state in which the reflective optical sensor 2245 has moved by 7 × Le from the A state to the + y side is “P7 state”, and the state in which the reflective optical sensor 2245 has moved by 8 × Le from the A state to the + y side is “P8”. State "that.

  (A) The reflective optical sensor 2245 is set to the A state, the light emitting unit E1 is turned on / off a plurality of times, and the total level value of the output signal of the corresponding light receiving unit is obtained every time the light emitting unit E1 is turned on / off.

  (B) The average value or median value of the obtained plurality of summed level values or the average value or median value of the plurality of summed level values excluding the abnormal value is obtained as a detection value. Here, the detected value is expressed as V1.

  (C) The reflective optical sensor 2245 is set to the P1 state, the light emitting unit E2 is turned on / off a plurality of times, and the total level value of the output signal of the corresponding light receiving unit is obtained every time the light emitting unit E2 is turned on / off.

  (D) The average value or median value of the obtained plurality of summed level values, or the average value or median value of the plurality of summed level values excluding the abnormal value is obtained as a detection value. Here, the detected value is expressed as V2.

  (E) When the reflective optical sensor 2245 is in the A state, the center of the position where the light emitted from the light emitting portion E1 is irradiated on the fixing belt 502 is c1, and the reflective optical sensor 2245 is in the P1 state. In addition, the center of the position where the light emitted from the light emitting portion E2 is irradiated on the fixing belt 502 is also c1. That is, if there is no variation, V1 and V2 should be equal. Therefore, in consideration of the above variation, (V1 / V2) is calculated as a correction coefficient α2 for correcting the detection value when the lighting light emitting unit is E2.

  (F) The reflective optical sensor 2245 is set to the P2 state, the light emitting unit E3 is turned on / off a plurality of times, and the total level value of the output signal of the corresponding light receiving unit is obtained every time the light emitting unit E3 is turned on / off.

  (G) The average value or median value of the obtained plurality of summed level values or the average value or median value of the plurality of summed level values excluding the abnormal value is obtained as a detection value. Here, the detected value is expressed as V3.

  (H) When the reflective optical sensor 2245 is in the A state, the center of the position where the light emitted from the light emitting portion E1 is irradiated on the fixing belt 502 is c1, and the reflective optical sensor 2245 is in the P2 state. Furthermore, the center of the position where the light emitted from the light emitting portion E3 is irradiated on the fixing belt 502 is also c1. That is, if there is no variation, V1 and V3 should be equal. Therefore, in consideration of the above variation, (V1 / V3) is calculated as a correction coefficient α3 for correcting the detection value when the lighting light emitting unit is E3.

  (I) The reflective optical sensor 2245 is set to the P3 state, the light emitting unit E4 is turned on / off a plurality of times, and the total level value of the output signal of the corresponding light receiving unit is obtained every time the light emitting unit E4 is turned on / off.

  (J) The average value or median value of the obtained plurality of summed level values, or the average value or median value of the plurality of summed level values excluding the abnormal value is obtained as a detection value. Here, the detected value is expressed as V4.

(K) When the reflective optical sensor 2245 is in the A state, the center of the position where the light emitted from the light emitting portion E1 is irradiated on the fixing belt 502 is c1, and when the reflective optical sensor 2245 is in the P3 state In addition, the center of the position where the light emitted from the light emitting portion E4 is irradiated on the fixing belt 502 is also c1. That is, if there is no variation, V1 and V4 should be equal. Therefore, in consideration of the above variation, (V1 / V4) is calculated as a correction coefficient α4 for correcting the detection value when the lighting light emitting unit is E4.
Thereafter, similarly, correction coefficients α5 to α10 are calculated.

  Moreover, although the said embodiment demonstrated the case where 10 illumination microlenses (LE1-LE10) and 12 light reception microlenses (LD0-LD11) were integrated, it is limited to this. is not.

  In the above-described embodiment, a processing device may be provided in the reflective optical sensor 2245, and the processing device may perform at least a part of the processing in the printer control device 2090 in the correction coefficient acquisition processing and the surface state check processing.

  Moreover, although the said embodiment demonstrated the case where the number of the light-receiving parts corresponding to one light-emitting part was three, it is not limited to this. For example, the number of light receiving parts corresponding to one light emitting part may be five.

  In the above-described embodiment, the case where the reflective optical sensor 2245 has ten light emitting units has been described. However, the present invention is not limited to this.

  In the above embodiment, the case where the size (diameter) of the light spot is substantially equal to Le has been described. However, the present invention is not limited to this, and the size (diameter) of the light spot may be smaller than Le. good.

  FIG. 23A shows a case where the number of light emitting units is four (E1 to E4) and the number of light receiving units is six (D0 to D5). In FIG. 23B, the sizes (diameters) of the four light spots (SP1 to SP4) emitted from the four light emitting portions (E1 to E4) and formed on the surface of the fixing belt 502 are shown. The case where it is smaller than Le is shown. Hereinafter, such a reflective optical sensor is referred to as a reflective optical sensor 2245A for convenience. The surface condition check process in this case will be described.

  First, in a state where the light emitting unit E4 is turned on, the total level value of the light receiving unit corresponding to the light emitting unit E4 is acquired while moving the reflective optical sensor 2245A in the + y direction at a predetermined speed.

  When the moving distance of the reflective optical sensor 2245A becomes Le, the movement of the reflective optical sensor 2245A is stopped, the light emitting unit E4 is turned off, and the light emitting unit E3 is turned on.

  Then, while the light emitting unit E3 is turned on, the total level value of the light receiving unit corresponding to the light emitting unit E3 is acquired while moving the reflective optical sensor 2245A in the -y direction at a predetermined speed.

  When the moving distance of the reflective optical sensor 2245A becomes Le, the movement of the reflective optical sensor 2245A is stopped, the light emitting unit E3 is turned off, and the light emitting unit E2 is turned on.

  Then, the total level value of the light receiving unit corresponding to the light emitting unit E2 is acquired while moving the reflective optical sensor 2245A in the + y direction at a predetermined speed with the light emitting unit E2 turned on.

  When the moving distance of the reflective optical sensor 2245A becomes Le, the movement of the reflective optical sensor 2245A is stopped, the light emitting unit E2 is turned off, and the light emitting unit E1 is turned on.

  Then, the total level value of the light receiving unit corresponding to the light emitting unit E1 is acquired while moving the reflective optical sensor 2245A in the -y direction at a predetermined speed with the light emitting unit E1 turned on.

  When the moving distance of the reflective optical sensor 2245A becomes Le, the movement of the reflective optical sensor 2245A is stopped, and the light emitting unit E1 is turned off.

  Then, the detection value is obtained in the same manner as described above, and the flaw density is obtained based on the decrease rate of the detection value.

  FIG. 24 shows the time change of the position of the light spot formed on the surface of the fixing belt 502 in the y-axis direction. In this case, even if the maximum movement amount of the reflective optical sensor 2245A is Le, a 4 × Le range is scanned with the light spot in the y-axis direction, and the flaw density within this range can be obtained.

  The moving speed of the reflective optical sensor 2245A is determined in accordance with the number of acquisitions of the total level value during the movement and the sampling time of the light receiving unit.

  Incidentally, in FIG. 25, the emission angle of the reflected light on the surface of the fixing belt 502 is shown for the case where the detection light is applied to the part having no flaw on the fixing belt 502 and the part having the flaw is applied. The relationship between θ (°) and light intensity, that is, the emission angle characteristic of reflected light is shown.

  According to this, it can be seen that there is almost no difference in the light intensity of the reflected light with | θ |> 1.7 ° between the case where the light is applied to the site having no flaw and the case where the light is applied to the region having the flaw.

  Therefore, as shown in FIG. 26, when the distance between the fixing belt 502 and the light receiving microlens in the z-axis direction is h, the center of the light receiving part Db and the −y side end of the light receiving part Da in the y axis direction. If the distance L to the portion is h × tan (1.7 °) or more, the amount of light received by the light receiving portion Da is not damaged at the site where the detection light spot SPb is formed. It doesn't change.

  As an example, in the reflective optical sensor 2245A, with respect to the y-axis direction, the distance between the center of the light receiving part D1 and the + y side end of the light receiving part D3, and the center of the light receiving part D2 and the + y side end of the light receiving part D4 If the distance Ld is equal to or greater than h × tan (1.7 °), the light emitting unit E1 and the light emitting unit E3, and the light emitting unit E2 and the light emitting unit E4 can be turned on simultaneously in the surface state check process. . The surface condition check process in this case will be described.

  First, while the light emitting unit E4 and the light emitting unit E2 are turned on, the reflection type optical sensor 2245A is moved in the + y direction at a predetermined speed, and the combined level value of the light receiving unit corresponding to the light emitting unit E4 and the light emitting unit E2 are set. The total level value of the corresponding light receiving unit is acquired.

  When the moving distance of the reflective optical sensor 2245A becomes Le, the movement of the reflective optical sensor 2245A is stopped, the light emitting part E4 and the light emitting part E2 are turned off, and the light emitting part E3 and the light emitting part E1 are turned on.

  Then, while the light emitting unit E3 and the light emitting unit E1 are turned on, the reflection type optical sensor 2245A is moved in the -y direction at a predetermined speed, and the combined level value of the light receiving unit corresponding to the light emitting unit E3 and the light emitting unit E1. The total level value of the light receiving unit corresponding to is acquired.

When the movement distance of the reflective optical sensor 2245A becomes Le, the movement of the reflective optical sensor 2245A is stopped, and the light emitting unit E3 and the light emitting unit E1 are turned off.
Then, the detection value is obtained in the same manner as described above, and the flaw density is obtained based on the decrease rate of the detection value.

  FIG. 28 shows the time change of the position of the light spot formed on the surface of the fixing belt 502 in the y-axis direction. In this case, even if the maximum movement amount of the reflective optical sensor 2245A is Le, a 4 × Le range is scanned with the light spot in the y-axis direction, and the flaw density within this range can be obtained.

  In the above embodiment, the case where one reflective optical sensor 2245 is provided has been described. However, the present invention is not limited to this, and a plurality of reflective optical sensors 2245 may be provided (see FIG. 29). .

  In the above-described embodiment, the case of a tandem multi-color printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow) has been described as an image forming apparatus. Is not to be done. For example, it may be a multicolor printer that further uses auxiliary colors, or a printer that forms a monochrome image.

  In the above-described embodiment, the case of a color printer has been described as the image forming apparatus. However, the present invention is not limited to this, and an image forming apparatus other than a printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated. There may be.

  DESCRIPTION OF SYMBOLS 100 ... Drive mechanism, 101 ... Slider, 102 ... Solenoid actuator, 103 ... Spring, 104 ... Spring, 105 ... Stopper, 106 ... Stopper, 107 ... Base member, 501 ... Pressure roller, 502 ... Fixing belt, 503 ... Fixing Roller, 504 ... Heating roller, 505 ... Tension roller, 2000 ... Color printer (image forming apparatus), 2010 ... Optical scanning device, 2030a-2030d ... Photosensitive drum, 2040 ... Intermediate transfer belt, 2050 ... Fixing device, 2090 ... Printer Control device (processing device), 2245 ... reflective optical sensor, D0 to D11 ... light receiving unit, E1 to E10 ... light emitting unit, LD0 to LD11 ... light receiving microlens, LE1 to LE10 ... illumination microlens.

Japanese Patent Laid-Open No. 5-113737 Japanese Patent No. 4632820 JP 2007-34068 A JP 2010-262203 A

Claims (10)

In an image forming apparatus having a fixing member for fixing an image on a recording medium moving in a first axis direction,
A plurality of light beams are emitted toward the fixing member, and a plurality of light spots having a predetermined pitch are formed on the surface of the fixing member with respect to a second axis direction orthogonal to the first axis direction, and reflected by the fixing member. A reflective optical sensor that receives light;
A drive mechanism for moving the reflective optical sensor in the second axis direction;
An image forming apparatus comprising: a processing device that obtains a surface state of the fixing member based on an output signal of the reflective optical sensor when the reflective optical sensor is at a plurality of positions different from each other with respect to the second axis direction. Using the predetermined pitch L and the number of light spots N in the plurality of light spots,
The image forming apparatus according to claim 1, wherein a maximum movement amount M of the reflective optical sensor by the driving mechanism is L ≦ M ≦ (N−1) L. The plurality of positions different from each other with respect to the second axis direction are three or more positions,
The image forming apparatus according to claim 1, wherein the three or more positions are equally spaced.   The output signal of the reflective optical sensor is an output signal of the reflective optical sensor when the plurality of light spots are sequentially formed on the surface of the fixing member one by one. The image forming apparatus according to claim 3. The reflective optical sensor is movable between the first position and the second position with respect to the second axial direction by the driving mechanism;
The processing apparatus includes: an output signal of the reflection type optical sensor when the reflection type optical sensor is moving from the first position to the second position; and the reflection type optical sensor from the second position to the first position. The image forming apparatus according to claim 1, wherein the surface state of the fixing member is obtained based on an output signal of the reflective optical sensor when moving to one position. When the reflective optical sensor is moved from the first position to the second position, only one light spot of the plurality of light spots is formed on the surface of the fixing member,
When the reflective optical sensor is moved from the second position to the first position, only one light spot different from the one light spot among the plurality of light spots is on the surface of the fixing member. The image forming apparatus according to claim 5, wherein the image forming apparatus is formed. The reflective optical sensor is disposed at different positions with respect to the second axis direction, and receives a plurality of light receiving portions that receive light reflected by the fixing member, and a plurality of condensing lenses corresponding to the plurality of light receiving portions. Have
The processing apparatus uses a distance h between the fixing member and the plurality of condenser lenses,
When the reflective optical sensor is moved from the first position to the second position, the plurality of light receiving units are separated by a plurality of h × tan (1.7 °) or more with respect to the second axis direction. A plurality of light spots corresponding to the light receiving portion are simultaneously formed on the surface of the fixing member,
When the reflective optical sensor is moved from the second position to the first position, the plurality of light spots are different from the plurality of light spots formed at the same time, and the second light receiving unit has the second light spot. 6. A plurality of light spots corresponding to a plurality of light receiving portions that are separated by h × tan (1.7 °) or more in the axial direction are simultaneously formed on the surface of the fixing member. Image forming apparatus.   The processing apparatus includes: the reflective optical sensor when the reflective optical sensor is in one position with respect to the second axis direction, and the plurality of light spots are sequentially formed on the surface of the fixing member one by one. The output signal and the reflective optical sensor are located at a position 1/2 times the predetermined pitch from the one position with respect to the second axis direction, and the plurality of light spots are sequentially placed on the surface of the fixing member one by one. 3. The image forming apparatus according to claim 1, wherein the surface state of the fixing member is obtained based on an output signal of the reflective optical sensor when formed on the surface of the fixing member. The reflective optical sensor has a plurality of light emitting units that are arranged at different positions with respect to the second axis direction and that emit a plurality of light and a plurality of light receiving units that receive the light reflected by the fixing member. And
The processing apparatus includes: the reflective optical sensor when the reflective optical sensor is in one position with respect to the second axis direction, and the plurality of light spots are sequentially formed on the surface of the fixing member one by one. When the output signal and the reflective optical sensor are located at a predetermined pitch apart from the one position with respect to the second axis direction, and the plurality of light spots are sequentially formed on the surface of the fixing member one by one The correction coefficient for correcting the variation in the characteristics of the plurality of light emitting units and the plurality of light receiving units is obtained based on the output signal of the reflective optical sensor. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the driving mechanism uses any one of a solenoid actuator, a piezoelectric actuator, and an electric motor as a driving device.

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