JP4621507B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer.

  2. Description of the Related Art Conventionally, an image forming apparatus that develops a latent image formed on a photoconductor as an image carrier using a liquid developer (hereinafter referred to as a developer) in which toner is dispersed in a carrier liquid is known (for example, Patent Document 1). In this image forming apparatus, a developing roller as a developer carrying member is brought into pressure contact with a photosensitive member to form a predetermined contact width (hereinafter referred to as a developing nip). In this developing nip, the toner in the developer adhering to the developing roller is transferred to the photosensitive member to develop the latent image on the photosensitive member. Further, the toner adhering to the background portion of the photoreceptor is removed by a sweep roller which is a toner removing means. Then, the toner image on the photosensitive member is transferred onto a transfer sheet as a transfer target by a transfer roller as a transfer unit, and fixed by a fixing unit, thereby completing a series of image forming steps.

JP 2002-278293 A

  However, depending on the processing accuracy of a rotating member such as a developing roller, a sweep roller, or a transfer roller that comes into contact with the photosensitive member, the roller diameter may vary between apparatuses or before and after component replacement. Therefore, even if the conditions of the drive motor for driving the rotating body are the same, a linear velocity difference may occur between the image carrier and the rotating body. Further, the rotating body may be worn due to contact with time, and a difference in linear velocity may occur between the photosensitive member and the rotating body. As described above, when a difference in linear velocity occurs between the photosensitive member and the rotating member, there is a possibility that a problem as described below occurs.

  For example, when a linear velocity difference occurs between the photosensitive member and the developing roller, the amount of developer pumped onto the latent image on the photosensitive member changes. When the linear velocity of the developing roller is higher than that of the photosensitive member, the pumping amount increases and the image density becomes high. Conversely, when the linear velocity of the developing roller is low, the pumping amount is developed and the image density becomes low. As a result, there is a difference in image density before and after the development roller replacement, or a density difference appears over time. In addition, when a linear velocity difference occurs between the photoconductor and the sweep roller or transfer roller, the sweep roller or transfer roller directly touches the developed image on the photoconductor. Disturbances such as crushing occur.

  The present invention has been made in view of the above problems. An object of the present invention is to provide an image forming apparatus capable of obtaining a stable image quality free from density differences, blurring, and squeezing regardless of the processing accuracy of the rotating body and wear over time.

In order to achieve the above object, the invention of claim 1 is directed to an image carrier and a latent image formed on the image carrier by contacting the image carrier and applying a liquid developer to the image carrier. A developing device comprising: a developing roller that makes an image appear as a toner image; and a sweeping roller that contacts the image carrier and removes fog toner attached to a background portion of the image carrier; and the image carrier And a transfer roller for transferring a toner image on the image carrier, a marking made of a magnetic material provided on the peripheral surface of the image carrier, and a magnetic for reading the marking An image carrier speed detecting means for detecting the rotation speed of the image carrier based on the detection result of the magnetic sensor, and the peripheral surfaces of the developing roller, the sweep roller, and the transfer roller, respectively. From the magnetic material provided And marking, and a plurality of magnetic sensor that reads the markings, on the basis of the detection results of the magnetic sensors, and the developing roller, rotating body speed detecting means for detecting a rotational speed of the sweep roller and the transfer roller, Based on the detection results of the image carrier speed detecting means and the rotating body speed detecting means , the relationship between the rotational speed of the image carrier and the rotational speeds of the developing roller, the sweep roller, and the transfer roller is predetermined. Rotating body control means for controlling the rotational speed of each roller so as to satisfy the following relationship, and during the initial operation, the developing roller, the sweep roller, and the transfer roller are separated from the image carrier, and the image is The rotational speed of the carrier is detected by the image carrier speed detecting means, the rotational speed of each roller is detected by the rotary body speed detecting means, and each low speed is detected by the rotating body control means. The image carrier is in a state where each roller is in contact with the image carrier from the end of image formation on the preceding recording medium to the start of image formation on the succeeding recording medium. The rotation speed of each roller is detected by the image carrier speed detection means, the rotation speed of each roller is detected by the rotation body speed detection means, and the rotation speed of each roller is controlled by the rotation body control means. The rotation speed of each roller is automatically set so that the rotation speed of the carrier and the rotation speed of each roller are substantially the same, or the relationship between the rotation speed of the image carrier and the rotation speed of each roller is a predetermined value. The changeover switch that switches whether to set the rotation speed of each roller manually so that the relationship is established, and the automatic setting that automatically sets the rotation speed of each roller, The rotational speed of each roller is almost the same. If not, an image forming operation stopping means for stopping the image forming operation is provided .

According to the present invention, it is possible to provide an image forming apparatus capable of obtaining a stable image quality free from density differences, blurring, crushing, and the like, regardless of the processing accuracy of the rotating body or wear over time. There is an effect. In addition, it is possible to suppress overloading of the image bearing member and the drive motor of the rotating member, and to suppress image disturbance and the like.

  Hereinafter, an embodiment of an image forming apparatus to which the present invention is applied will be described. FIG. 1 is a configuration diagram showing the overall schematic configuration of the image forming apparatus. As shown in FIG. 1, the image forming apparatus includes a charging device 2, an exposure device 3, a developing roller 4 as a developer carrier, and a toner removing unit around a drum-shaped photosensitive member 1 as an image carrier. A developing device 6 having a certain sweep roller 5, an intermediate transfer roller 7 as a transfer means, a secondary transfer roller 8, a charge eliminating device 9, and a cleaning blade 10 are arranged. As the charging device 2, a form such as a roller or a charger can be used. As the exposure device 3, an LED, a laser scanning optical system, or the like can be used. Further, in the apparatus main body, a paper feed cassette 11 that houses a transfer paper P that is a recording medium is provided.

  The developing device 6 mainly includes a developer tank 12 containing a liquid developer 11 therein, a stirring tank 13, a developing roller 4, a coating roller 15, an anilox roller 16, and a sweep roller 5. The developing roller 4, the application roller 15, and the sweep roller 5 are provided with cleaning members 4a, 15a, and 5a made of metal blades or rubber blades, respectively, and their surfaces are initialized. Each of the cleaning members 4a, 15a, and 5a is not limited to a blade but may be a roller type. The developer 11 in the developer tank 12 is agitated and conveyed by developer agitating and conveying members 17 and 18 that rotate in opposite directions and pumped up by the anilox roller 16. The developer 11 pumped up by the anilox roller 16 is supplied to the developing roller 4 through the application roller 15. When the amount of the developer 11 in the developer tank 12 falls below a predetermined amount due to toner consumption, toner is supplied into the agitation tank 13 from a toner bottle 19 configured to be detachable from the apparatus main body. The developer 11 in the stirring tank 13 is stirred by the stirring member 20 and sent to the developer tank 12 by the stirring pump 21.

  In the image forming apparatus having the above-described configuration, the photosensitive member 1 is rotationally driven in the direction of arrow A, and is uniformly charged by the charging device 2, and then an original image is irradiated and imaged by the exposure device 3 to form an electrostatic latent image. Illuminated and imaged. The electrostatic latent image on the photosensitive member 1 is developed when passing through a developing region facing the developing roller 4 of the developing device 6 and is manifested as a toner image. Then, the fog toner adhering to the background portion of the photoreceptor 1 is removed by the sweep roller 5. Thereafter, the toner image on the photosensitive member 1 is primarily transferred to the intermediate transfer roller 7 and is fed at a predetermined timing from the paper feed unit 11 by the paper feed roller 22 and the registration roller pair 23 at a portion facing the secondary transfer roller 8. It is transferred to transfer paper P to be paper. After the primary transfer, the photosensitive member 1 is prepared for the next copy by removing the residual charge by the static eliminator 9 and removing the residual toner by the cleaning blade 10. Further, the transfer paper P onto which the toner image has been transferred passes through a fixing device (not shown) and is discharged outside the apparatus.

  Next, a characteristic configuration of the image forming apparatus will be described. FIG. 2 is a configuration diagram illustrating a schematic configuration of a main part of the image forming apparatus. As shown in FIG. 2, the photoreceptor 1, the developing roller 4, the sweep roller 5, and the transfer roller 7 are rotationally driven by drive motors 24, 25, 26, and 27, respectively. A marking 30 provided on the peripheral surface of the photoreceptor 1 and an optical sensor 31 for detecting the marking 30 are provided as image carrier speed detection means for detecting the rotational speed of the photoreceptor 1. Also, markings provided on the peripheral surfaces of the rollers 4, 5, and 7 as rotating body speed detecting means for detecting the rotational speed of the developing roller 4, the sweep roller 5, and the transfer roller 7 (hereinafter referred to as each roller). 32, 33, and 34 and optical sensors 35, 36, and 37 for detecting marking are provided, respectively.

  The photoconductor markings 30 are provided at predetermined intervals so as to periodically generate a magnitude of return of the amount of light irradiated from the optical sensor 31 (the presence or absence of marking). Since the photoreceptor 1 itself generally has a high light reflectance, the color of the marking 30 for the photoreceptor is a color with a low reflectance of light, for example, a matte black, and the amount of change in the return amount of light from the optical sensor 31 (marking) Increase or decrease). When the rotating body such as the developing roller 4, the sweep roller 5, and the transfer roller 7 is composed of a color having a low light reflectance, such as black, the colors of the markings 32, 33, and 34 have a higher reflectance. It is preferable to use a color such as silver or white, and to increase the amount of change in the amount of light returned from the optical sensors 35, 36, and 37 (the presence or absence of marking).

  For each optical sensor 31, 35, 36, 37, a light emitting / receiving element such as a laser or LED can be used. FIG. 3 is a configuration diagram showing the configuration around the optical sensor. As shown in FIG. 3, for example, the optical sensor 31 for the photoreceptor irradiates light from the light emitting element 31 a toward the marking 30 when the photoreceptor 1 rotates, and the light receiving element 31 b detects the light reflected from the marking 30. Then, the time for which the markings 30 arranged at equal intervals pass is measured. Measurement data from each optical sensor is converted into digital data by the A / D converter 42 and output. The amount of light emitted from the optical sensor 31 is controlled by the output voltage Vcc of the variable power supply 48. The installation locations of the optical sensors 31, 35, 36, and 37 are provided on the outer peripheral surfaces of the photoreceptor 1 and the rollers 4, 5, and 7 in FIG. 2, but may be the end surfaces of the rollers. And it may be the inner peripheral surface of each roller.

  In general, a liquid developer uses silicon oil, isopar, or other vegetable oil as a carrier liquid. Therefore, a liquid film peculiar to the liquid developer is formed on the surface of the photoreceptor 1 and each of the rollers 4, 5, and 7. So-called shine occurs. Even if an attempt is made to perform an accurate measurement with the optical sensors 31, 35, 36, and 37 in this state, there is a possibility that the accurate measurement cannot be performed due to the obstruction. Therefore, it is preferable to provide a marking cleaning means for removing the liquid film on each of the markings 30, 32, 33, 34 before the measurement by the optical sensors 31, 35, 36, 37. As the marking cleaning means, as shown in FIG. 2, marking cleaning members 38, 39, 40, and 41 made of a porous foam member may be used, a cleaning blade made of an elastic member, or a cleaning roller. May be used.

  In addition, a marking cleaning member may not be newly provided, and may also be used as a cleaning member that cleans the toner remaining in the image forming effective area of the photoreceptor 1 and the rollers 4, 5, and 7 that is generally provided conventionally. Moreover, you may install both the conventional cleaning member and the cleaning member for marking. FIG. 4 is a configuration diagram showing an example in which the photosensitive member cleaning blade is extended to the marking position. For example, as shown in FIG. 4, the cleaning blade 10 that has conventionally been formed only up to the width of the image forming area may be extended to the marking position outside the image forming area. By removing the toner with the cleaning blade 10 prior to the cleaning operation by the marking cleaning member 38, the marking cleaning member 38 can be clogged with the toner and the replacement life can be extended. In addition, since the marking 30 is detected by the optical sensor 31, cleaning is performed twice, so that the influence of shine is further reduced and accurate measurement is possible. The photosensitive member optical sensor 31 is installed before the developer is applied onto the photosensitive member 1 by the developing roller 4, that is, downstream of the cleaning blade 10 in the rotational direction of the photosensitive member and more than the developing roller 4. It is preferable to be on the upstream side of the photoconductor rotation direction. Thereby, the optical sensor 31 can measure the marking 30 without being affected by the toner.

  The image forming apparatus according to the present embodiment includes a CPU 50 as a control unit that controls the rotation speeds of the developing roller 4, the sweep roller 5, and the transfer roller 7 based on detection results from the optical sensors 31, 35, 36, and 37. A RAM 51 and a ROM 52 are provided. The CPU 50 is connected to the optical sensors 31, 35, 36, and 37 via the A / D / D / A converters 42, 43, 44, and 45, and the detection data from each of the optical sensors 31, 35, 36, and 37 is A Obtained as digital data via the / D converters 42, 43, 44, 45, and the rotational speeds of the photoreceptor 1 and the rollers 4, 5, 7 are calculated. Then, as will be described later, the CPU 50 refers to the data prepared in advance in the ROM 51 based on the calculation result, and performs the rotation speed variable operation of each of the rollers 4, 5, 7. Specifically, the CPU 50 calculates the rotational values of the drive motors 24, 25, 26, and 27 of the photosensitive member 1 and the rollers 4, 5, and 7, and the motor pulse generation circuits 54, 55, 56, and To 57. The motor pulse generation circuits 54, 55, 56 and 57 generate pulse signals based on the transmitted data and transmit them to the motor drivers 58, 59, 60 and 61. The motor drivers 58, 59, 60 and 61 rotate the drive motors 24, 25, 26 and 27 to drive the photoreceptor 1 and the rollers 4, 5 and 7 to rotate. The CPU 50 is connected to an operation panel 53 that can be input from the outside.

  When detecting the rotational speeds of the photosensitive member 1 and the rollers 4, 5, and 7 or changing the rotational speed, it is preferable to separate the photosensitive member 1 from the rollers 4, 5, and 7. Therefore, the rotational speed control timing of each of the rollers 4, 5, and 7 is preferably performed between the sheets from the initial operation or the end of image formation on the preceding transfer sheet to the start of image formation on the subsequent transfer sheet. Changing the rotational speed of the drive motors 26 and 27 of the rollers 5 and 7 while the toner image is passing under the sweep roller 5 or transferring to the transfer roller 7 may cause image distortion. Further, if the rotation speed of the drive motors 25, 26, 27 is changed while the rollers 4, 5, 7 are in contact with the photosensitive member 1, there is a risk of step-out when a stepping motor is used. Even when a motor is used, the drive motor is overloaded, and an accurate rotation speed cannot be measured, or the machine may be damaged. FIG. 5 is a configuration diagram illustrating the contact / separation mechanism of the sweep roller and the transfer roller. In FIG. 5, the hinge portion installed on the cam is not shown, but the left and right cams of the roller are interlocked with the hinge portion, and are indicated by one-point diagonal lines in the drawing. The cam of the developing roller 4 is not shown. As shown in FIG. 5, the contact / separation mechanism of the sweep roller 5 and the transfer roller 7 includes cams 62 and 63, cam drive motors 64 and 65, motor pulse generation circuits 66 and 67, cam motor drivers 68 and 69, roller adders. It comprises pressure springs 70, 71 and the like. For example, when it is desired to separate the sweep roller 5 from the photosensitive member 1, the cam 62 may be rotated by the cam drive motor 64 and stopped at a position close to the upper fulcrum. When the sweep roller 5 is brought into contact with the photosensitive member 1, the cam 62 is rotated by the cam drive motor 64 and stopped at a position near the lower fulcrum, and the sweep roller 5 is pressed against the surface of the photosensitive member 1 by the spring 70.

  However, when the rotational speeds of the rollers 4, 5, and 7 are controlled in a state where the rollers 4, 5, and 7 are separated from the photoconductor 1 during the initial operation, the rotational speeds of the rollers 4, 5, and 7 are substantially the same. It is an accurate value. Therefore, when adjusting the rotational speeds of the rollers 4, 5, and 7 between the sheets, it is determined that the overload on the drive motors 25, 26, 27 is small because the adjustment range is small, and the rollers 4, 5, 7 may be performed without being separated from the photosensitive member 1. As a result, a mechanical operation of separating the rollers 4, 5, and 7 from the photosensitive member 1 is not required, so that the space between the sheets can be reduced and high-speed correspondence is possible.

  Hereinafter, an operation method for controlling the rotation speeds of the photosensitive member 1, the developing roller 4, the sweep roller 5, and the transfer roller 7 will be specifically described. First, when the rollers 4, 5, and 7 are replaced due to the lifespan of the rollers 4, 5, and 7, the operator or service person inputs the target motor rotation speed (nominal number) and uses this as the rotation reference. Value. The CPU 50 separates the rollers 4, 5, 7 from the photoreceptor 1, and the markings 30, 32 with the optical sensors 31, 35, 36, 37 provided on the photoreceptor 1 and the rollers 4, 5, 7. , 33 and 34 are measured. The CPU 50 obtains this signal as digital data by the A / D converters 42, 43, 44, 45 and calculates the rotational speeds of the photoreceptor 1 and the rollers 4, 5, 7. Then, the CPU 50 compares the calculated data with the rotation reference value stored in the ROM 52, and the rotation speed of the photosensitive member 1 and the rotation speeds of the rollers 4, 5, and 7 are such that no dragged image is generated. The motor rotation value closest to the rotation reference value for achieving substantially the same speed (ideally perfect speed) is calculated. The CPU 50 transmits the calculated value to the motor pulse generation circuits 54, 55, 56 and 57. The motor pulse generation circuits 54, 55, 56 and 57 generate pulse signals based on the transmitted calculated values and transmit them to the motor drivers 58, 59, 60 and 61. The motor drivers 58, 59, 60 and 61 rotate the drive motors 24, 25, 26 and 27 to drive the photoreceptor 1 and the rollers 4, 5 and 7 to rotate.

  In the above operation method, the operator or service person inputs the rotation reference values of the rollers 4, 5, and 7 through the operation panel. However, the present invention is not limited to this method. For example, although it takes more time than the above method, the operation method described below may be used. First, the optical sensors 31, 35, 36, and 37 are provided with markings 30, 32, and 32 provided on the photosensitive member 1 and the rollers 4, 5, 7 in a state where the rollers 4, 5, 7 are separated from the photosensitive member 1. The transit times of 33 and 34 are measured. The CPU 50 obtains this signal as digital data by the A / D converters 42, 43, 44, 45 and calculates the rotational speeds of the photoreceptor 1 and the rollers 4, 5, 7. Then, referring to data prepared in advance in the ROM 52, when the photosensitive member 1 and the rollers 4, 5, and 7 are rotated in contact with each other, the actual rotational speeds of the photosensitive member 1 and the rollers are substantially the same. As described above, the linear velocity difference between the photosensitive member 1 and the rollers 4, 5, and 7 in a state where the photosensitive member 1 and the rollers 4, 5, and 7 are separated from each other is calculated. Then, frequency data to be sent to the drive motors 24, 25, 26, 27 is obtained from the relational data between the linear velocity difference prepared in the ROM 52 and the frequency to the drive motor, and the motor pulse generation circuits 54, 55, 56, 57 are obtained. Send data to. The motor pulse generation circuits 54, 55, 56 and 57 generate pulse signals based on the transmitted data and transmit them to the motor drivers 58, 59, 60 and 61. The motor drivers 58, 59, 60 and 61 rotate the drive motors 24, 25, 26 and 27 to drive the photoreceptor 1 and the rollers 4, 5 and 7 to rotate. Next, the rollers 4, 5, 7 are brought into spring contact with the photoreceptor 1, and the actual rotational speeds of the photoreceptor 1 and the rollers 4, 5, 7 are detected again by the optical sensors 31, 35, 36, 37, It is confirmed that the speed is substantially the same (ideally perfect speed) to the extent that no image drag occurs between the photosensitive member 1 and the rollers 4, 5, 7.

  FIG. 6 is a partial configuration diagram illustrating a partial configuration of the image forming apparatus. As described above, when the actual rotation speed of the photosensitive member 1 and the rollers 4, 5, and 7 does not become substantially the same speed, an abnormal image such as blurring or blurring may occur. For this reason, the CPU 50 may determine that the apparatus is abnormal and display the fact on the operation panel 53. You may make it display on an operator's external display through RAN. At the same time, the CPU 50 may output an engine operation abnormality signal to stop the image forming operation.

  In the method described above, the CPU 50 automatically sets the rotational speed of the photosensitive member 1 and each of the rollers 4, 5, and 7 to be substantially the same speed. The motor rotation speeds of the drive motors 25, 26, and 27 may be input as numerical values. As shown in FIG. 6, in the image forming apparatus provided with the automatic / manual changeover switch 72, an operator or a service person can intentionally generate a linear velocity difference between the photosensitive member 1 and the rollers 4, 5, 7. it can. For example, by intentionally generating a linear velocity difference between the photoreceptor 1 and the developing roller 4, the density change can be caused by changing the amount of developer applied to the latent image on the photoreceptor 1. Any density image can be obtained. In addition, by intentionally generating a linear velocity difference between the photoconductor 1 and the sweep roller 5 or between the photoconductor 1 and the transfer roller 7, a so-called extended image is obtained in which characters and images are thickened in the sub-scanning direction. It is possible to obtain an image with impact.

  By the way, the positions of the markings 30, 32, 33, and 34, which serve as a reference for the rotation speed of the optical sensors 31, 35, 36, and 37, are determined from the standpoint of preventing the contamination of the markings. It is desirable to provide inside 7. However, it may not be provided depending on the size and strength of parts. As shown in FIG. 2, when the markings 30, 32, 33, and 34 are provided on the outer peripheral surfaces of the photosensitive member 1 and the rollers 4, 5, and 7, the optical sensors 31, 35, 36, and 37 are erroneous. In order to prevent detection, a cleaning device that removes the developer on the markings 30, 32, 33, and 34 is required. Further, a dripping prevention member at the cleaning unit is also required. Therefore, it is disadvantageous for the downsizing of the apparatus and the number of consumables increases. Therefore, in the above-described embodiment, the optical sensors 31, 35, 36, and 37 are used as the image carrier speed detection means and the rotation body speed detection means. However, as the image carrier speed detection means and the rotation body speed detection means, As shown in FIG. 7, a marking 80 made of a magnetic material and a magnetic sensor 81 may be used. When a magnetic sensor is used, a marking cleaning mechanism is not required, and an accurate rotation speed can be detected regardless of contamination by the liquid developer.

As described above, according to the image forming apparatus according to the present embodiment, the CPU 50 is based on the detection results of the optical sensors 31 and 35 that are the image carrier speed detection unit and the rotating body speed detection unit, and the photoreceptor 1 that is the image carrier. The driving motor 25 of the developing roller 4 is controlled so that the actual rotation speed of the developing roller 4 is substantially the same. Therefore, there is no difference in density before and after the replacement of the developing roller 4 due to the difference in linear velocity between the photosensitive member 1 and the developing roller 4, and no difference in density with time. Also, it is possible to obtain an arbitrary image density by causing the CPU 50 to generate an arbitrary linear velocity difference between the photosensitive member 1 and the developing roller 4. Furthermore, since the rotation speed of the developing roller 4 can be controlled regardless of the processing accuracy at the time of manufacturing the roller, the processing accuracy can be roughened and the cost can be reduced.
Further, according to the image forming apparatus according to the present embodiment, the CPU 50 determines that the actual rotational speeds of the photosensitive member 1 and the sweep roller 4 or the transfer roller 7 are substantially the same based on the detection results of the optical sensors 31, 36, and 37. The drive motors 26 and 27 of the rollers 4 and 7 are controlled so that For this reason, an abnormal image such as blurring or blurring does not occur due to a difference in linear velocity between the photosensitive member 1 and the rollers 4 and 7. Further, by generating an arbitrary linear velocity difference between the photosensitive member 1 and the sweep roller 4 and the transfer roller 7 by the CPU 50, it is also possible to obtain an image having an impact such as a so-called extended image. Furthermore, since the actual rotational speeds of the sweep roller 4 and the transfer roller 7 can be controlled regardless of the processing accuracy at the time of manufacturing the roller, the processing accuracy can be roughened and the cost can be reduced.
Further, according to the image forming apparatus according to the present embodiment, when the rotational speed of the photosensitive member 1, the developing roller 4, the sweep roller 5, and the transfer roller 7 is measured or when the rotational speed is variable, the photosensitive member 1, the developing roller 4, and the sweeping roller. The roller 5 and the transfer roller 7 are separated from each other. Therefore, there is no overload on the drive motors of the photosensitive member 1 and the rollers 4, 5, 7.
Further, according to the image forming apparatus according to the present embodiment, the rotational speed of the photosensitive member 1, the developing roller 4, the sweep roller 5, and the transfer roller 7 is measured or the rotational speed variable operation is performed during the initial operation or between the sheets. For this reason, the image is not disturbed.
Further, according to the image forming apparatus of the present embodiment, the photosensitive member marking 30, the optical sensor 31, and the cleaning member 38 are provided as speed detection means of the photosensitive member 1. Since the optical sensor 31 detects the marking for the photosensitive member cleaned by the cleaning member 38, accurate detection is possible.
Further, according to the image forming apparatus according to the present embodiment, the marking rollers 32, 33, 34, the optical sensors 35, 36, 37, the cleaning member 39, as speed detection means for the developing roller 4, the sweep roller 5, and the transfer roller 7. 40 and 41 are provided. Since the optical sensors 35, 36, and 37 detect the markings 32, 33, and 34 cleaned by the cleaning members 39, 40, and 41, accurate detection is possible.
Further, according to the image forming apparatus of the present embodiment, the photoreceptor marking 30 is cleaned by the cleaning blade 10 which is an image carrier cleaning means, and then cleaned again by the cleaning member 38. Therefore, since the cleaning member 38 cleans the marking 31 that has been cleaned in advance, the cleaning member 38 is less likely to be clogged with toner, and the replacement life can be extended. Moreover, since the optical sensor 31 can detect the marking 31 that has been cleaned twice, more accurate measurement can be performed.
Further, according to the image forming apparatus according to the present embodiment, the photoconductor 1 is configured with a color having a high light reflectance, and the marking 30 is configured with a color having a low light reflectance. Thereby, the amount of change in the return of light in the optical sensor 31 can be increased.
Further, according to the image forming apparatus according to the present embodiment, the developing roller 4, the sweep roller 5, and the transfer roller 7 are colors having low light reflectance, and the markings 32, 33, and 34 are colors having low light reflectance. Composed. Thereby, in the optical sensors 35, 36, and 37, the amount of change in light return can be increased.
Further, according to the image forming apparatus according to the present embodiment, the magnetic sensor 80 and the magnetic marking 81 can be used as the image carrier speed detection unit and the rotating body speed detection unit. This eliminates the need for a marking cleaning mechanism, and enables accurate measurement regardless of contamination with the developer.
Further, according to the image forming apparatus according to the present embodiment, the rotation speed of the photosensitive member 1 and the rollers 4, 5, and 7 can be manually controlled by an operator or a service person. Etc. can be obtained.
Further, according to the image forming apparatus according to the present embodiment, before an abnormal image is generated due to a difference in linear velocity between the photosensitive member 1 and each of the rollers 4, 5, 7, an operator or serviceman is an operation panel serving as a display unit. 53 can know the abnormality.
Further, according to the image forming apparatus according to the present embodiment, before an abnormal image is generated due to a difference in linear velocity between the photosensitive member 1 and each of the rollers 4, 5, 7, an engine operation abnormal signal is generated to perform the image forming operation. Stop.

1 is a configuration diagram showing an overall schematic configuration of an image forming apparatus according to an embodiment. FIG. 2 is a configuration diagram illustrating a schematic configuration of a main part of the image forming apparatus. The block diagram which shows the structure around an optical sensor. The block diagram which shows the example which extended the photoreceptor cleaning blade to the position of marking. The block diagram explaining the contacting / separating mechanism of a sweep roller and a transfer roller. FIG. 3 is a partial configuration diagram illustrating a partial configuration of the image forming apparatus. The block diagram which shows the structure around a magnetic sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 4 Developing roller 5 Sweep roller 7 Transfer roller 10 Cleaning blade 30, 32, 33, 34 Marking 31, 35, 36, 37 Optical sensor 38, 39, 40, 41 Cleaning member

Claims (1)

An image carrier;
A developing roller that contacts the image carrier, applies a liquid developer to the image carrier, and makes a latent image formed on the image carrier appear as a toner image, and contacts the image carrier; A developing device comprising a sweep roller for removing fog toner adhering to the background portion of the image carrier;
In an image forming apparatus comprising a transfer roller in contact with the image carrier and to which a toner image on the image carrier is transferred .
An image having a marking made of a magnetic material provided on a peripheral surface of the image carrier and a magnetic sensor for reading the marking, and detecting a rotation speed of the image carrier based on a detection result of the magnetic sensor. A carrier speed detection means;
The developing roller, the sweeping roller, and the transfer roller each having a marking made of a magnetic material provided on each peripheral surface, and a plurality of magnetic sensors for reading the marking, and based on the detection result of each magnetic sensor, A rotating body speed detecting means for detecting the rotational speed of the developing roller, the sweep roller, and the transfer roller;
Based on the detection results of the image carrier speed detecting means and the rotating body speed detecting means , the relationship between the rotational speed of the image carrier and the rotational speeds of the developing roller, the sweep roller, and the transfer roller is predetermined. A rotating body control means for controlling the rotational speed of each roller so as to satisfy the relationship
During the initial operation, the developing roller, the sweep roller, and the transfer roller are separated from the image carrier, and the rotation speed of the image carrier is detected by the image carrier velocity detection means. Is detected by the rotating body speed detecting means, and the rotating speed of each roller is controlled by the rotating body control means, and from the end of image formation on the preceding recording medium to the start of image formation on the succeeding recording medium. In the state where each roller is in contact with the image carrier, the rotational speed of the image carrier is detected by the image carrier speed detector, and the rotational speed of each roller is detected by the rotor speed detector. The control means controls the rotational speed of each roller.
The rotation speed of each roller is automatically set so that the rotation speed of the image carrier and the rotation speed of each roller are substantially the same, or the relationship between the rotation speed of the image carrier and the rotation speed of each roller is A changeover switch for switching whether to manually set the rotation speed of each roller so as to have a predetermined relationship;
In the automatic setting for automatically setting the rotation speed of each roller, the image forming operation is stopped when the rotation speed of the image carrier and each roller is not substantially the same by the rotation body control means. An image forming apparatus comprising: an image forming operation stopping unit that causes the image forming operation to stop .

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