JP4951268B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that performs development by supplying a developer to the surface of an image carrier, and more particularly to control for applying a lubricant to the surface of an image carrier.

  An electrophotographic image forming apparatus that forms an image by transferring a developer image (hereinafter referred to as a toner image) formed on the basis of image information onto a sheet achieves higher image forming speed and higher image quality. As a result, the toner is becoming smaller in particle size (about 8 μm or less). However, in order to reduce the toner particle size, it is difficult to remove the toner remaining on the surface of the photosensitive drum after the transfer of the toner image onto the paper by a cleaning means such as a cleaning blade. Therefore, the contact force of the cleaning blade to the surface of the photosensitive drum must be increased as compared with the conventional case, and the life of the photosensitive drum is reduced.

  Thus, some recent image forming apparatuses have a configuration in which a lubricant is applied to the surface of the photosensitive drum in order to improve the releasability of the toner. The application of the lubricant has been performed by, for example, a lubricant application unit having a solid lubricant in contact with the surface of the rotating photosensitive drum.

  However, the lubricant cannot always be supplied at a constant application amount from the beginning of the operation of the image forming apparatus due to the deterioration of the lubricant application means and the cleaning means due to long-term use. For example, the lubricant application means is deteriorated by use, such as the shape of a solid lubricant changing to an indeterminate shape, and the amount of lubricant applied to the photosensitive drum changes. The amount of the lubricant removed from the surface of the photosensitive drum varies depending on the wear of the cleaning blade.

  Since the coating amount of the lubricant also affects the charging amount of the photosensitive drum by the charging device, the image quality is not stable unless the coating amount is constant. For example, when the charging device is a roller or brush contact type configuration, if there is a large amount of lubricant, the amount of current required to charge the surface of the photosensitive drum to a predetermined potential using the charging device increases, and toner fogging occurs. It tends to occur. On the other hand, when the amount of the lubricant is small, the cleaning property of the toner is deteriorated, which causes image defects. Furthermore, there arises a problem that the photosensitive member is easily worn.

  Further, the actual amount of lubricant applied on the surface of the photosensitive drum cannot be directly detected.

Therefore, in order to perform stable lubricant application, recent image forming apparatuses include a rotational drive state of a charging roller and a lubricant application roller, a detection density of a reference pattern formed on the surface of the photoconductor, and a drive of the photoconductor. There is a configuration in which the application of the lubricant is controlled based on conditions relating to the application amount of the lubricant such as torque (see, for example, Patent Documents 1, 2, and 3).
JP-A-8-305236 JP 2000-338733 A JP 2005-181742 A

  However, in the configurations of Patent Documents 1 to 3 described above, it is difficult to accurately detect the amount of lubricant on the surface of the photoreceptor that is actually applied.

  An object of the present invention is to maintain an optimum coating amount by controlling a coating operation based on an accurate coating amount of a lubricant actually applied on the surface of an image carrier, and to maintain a high-quality image. An object of the present invention is to provide an image forming apparatus capable of performing the above.

  In order to solve the above problems, the present invention has the following configuration.

(1) An image forming apparatus according to the present invention includes an image carrier, a charging unit, a developer carrier, a cleaning unit, a lubricant application unit, a development current detection unit, a storage unit, and a control unit. I have.

The image carrier carries a latent image on the surface. The charging unit charges the surface of the image carrier. The developer carrier has a peripheral surface that abuts the surface of the image carrier, or a developer is supplied to the latent image in a developing area facing the surface of the image carrier to form a developer image on the surface of the image carrier. To do. The cleaning means removes deposits on the surface of the image carrier after applying the lubricant until the surface of the image carrier passes through the transfer position for transferring the developer image onto the paper and reaches the charging means. Remove. The lubricant applying unit applies a fatty acid metal salt as a lubricant to the surface of the image carrier after the developer image is transferred until the surface of the image carrier passes through the transfer position and reaches the cleaning unit. . The development current detection means detects a current value between the developer carrier and the image carrier in the development area. The storage unit determines the current value between the developer carrier and the image carrier in the development area when an appropriate amount of lubricant to be applied to the surface of the image carrier is applied to the surface of the image carrier. Store as a value. The control means controls the amount of lubricant applied by the lubricant applying means based on the current value detected by the developing current detecting means. For this reason, the control means determines whether the lubricant applied by the lubricant application means depends on whether the current value detected by the developing current detecting means when the developer image of the predetermined determination image is formed is larger or smaller than the reference current value. Reduce or increase the coating amount.

  In this configuration, the lubricant application unit is driven based on the current value between the developer carrier and the image carrier in the development region detected when the developer image of the predetermined determination image is formed. Be controlled. Since the current value between the developer carrier and the image carrier in the development area varies depending on the amount of lubricant applied, the exact amount of actual lubricant on the surface of the image carrier can be directly determined. Shown in The application amount is adjusted by controlling the drive of the lubricant application unit based on the current value, and the application amount of the lubricant on the surface of the image carrier is kept constant.

  (2) In the configuration of (1), the image forming apparatus further includes a storage unit. The storage unit determines the current value between the developer carrier and the image carrier in the development area when an appropriate amount of lubricant to be applied to the surface of the image carrier is applied to the surface of the image carrier. Store as a value. The control means controls the driving of the lubricant applying means based on the difference between the current value detected by the developing current detection means and the reference current value.

  In this configuration, the developer carrying member in the actual developing region detected by the developing current detecting means from the reference current value in a state where an optimal amount of lubricant is applied on the surface of the image carrier that is stored in advance. The drive of the lubricant application means is controlled depending on how far the current value between the image carrier and the image carrier is. That is, the subsequent control of the application of the lubricant is changed depending on how far the actual amount of the lubricant on the surface of the image carrier is from the optimum amount. Therefore, an optimal amount of lubricant is applied on the surface of the image carrier with simpler control.

  (3) In the configuration of (2) above, the image forming apparatus further includes a temperature detection unit and a humidity detection unit. The temperature detecting means detects the temperature around the image carrier. The humidity detecting means detects the humidity around the image carrier. The reference current value includes a plurality of values corresponding to a plurality of temperature and humidity conditions. The control unit reads from the storage unit a temperature value detected by the temperature detection unit and a reference current value that matches the humidity value detected by the humidity detection unit among the plurality of reference current values.

  In this configuration, a plurality of reference current values corresponding to temperature and humidity conditions are stored in the storage unit. In addition, the lubricant application unit is controlled based on the difference between the detected current value and the reference current value that matches the detected temperature value and humidity value. Since the current value between the developer bearing member and the image bearing member in the development region varies depending on the temperature and humidity conditions, the reference current value also varies. Accordingly, since the lubricant application unit is controlled based on the reference current value corresponding to the temperature and humidity conditions, the amount of lubricant applied on the surface of the image carrier is not affected by the temperature and humidity conditions.

  (4) In the configuration of (2), the image forming apparatus further includes a rotation speed measuring unit. The rotational speed measuring means measures an integrated value of the rotational speed of the image carrier. The reference current value includes a plurality of values corresponding to each of the integrated values of the plurality of rotation speeds. The control means reads a reference current value that matches the integrated value of the rotational speed measured by the rotational speed measuring means from the storage unit.

  In this configuration, a plurality of reference current values corresponding to the rotation speed condition of the image carrier are stored in the storage unit. Further, the lubricant application unit is controlled based on the difference between the reference current value that matches the measured rotational speed and the detected current value. The current value between the developer bearing member and the image bearing member in the development area varies depending on the degree of wear on the surface of the image bearing member. That is, it changes according to the integrated value of the rotational speed of the image carrier. As the image carrier is used, the surface is shaved due to wear and the film thickness decreases, and the capacitance (C) increases. Therefore, if the surface of the image carrier is maintained at a constant voltage (V), the accumulated charge (Q) increases and the current also increases. Accordingly, since the lubricant application means is controlled based on the reference current value according to the rotational speed condition, the integrated value of the rotational speed of the image carrier of the lubricant of the image carrier and the degree of wear of the surface of the image carrier. Not affected by.

  (5) In the configuration of (2), the image forming apparatus further includes a display unit. The display means displays the state of the main device. The storage unit stores an upper limit current value higher than the reference current value and a lower limit current value lower than the reference current value. The control means drives the lubricant application means based on the difference between the current value and the reference current value when it is determined that the current value detected by the development current detection means is not less than the lower limit current value and not more than the upper limit current value. When it is determined that the current value is less than the lower limit current value or greater than the upper limit current value, the image forming operation is prohibited and the abnormal state of the main device is displayed on the display means.

  In this configuration, in addition to the reference current value, the upper limit current value and the lower limit current value are stored in the storage unit. The upper limit current value and the lower limit current value indicate, for example, the upper limit and lower limit of the current value detected in a normal operating state. When a value outside this current value range is detected, the main unit is not operating normally. Indicates. Accordingly, when the detected current value is less than the lower limit value or greater than the upper limit value, the image forming operation is prohibited and the main device abnormal state is displayed on the display means. Will be informed.

  (6) In the configuration of (1) above, the lubricant applying means applies a fatty acid metal salt as a lubricant.

  In this configuration, a fatty acid metal salt is used as the lubricant. The fatty acid metal salt matches the photoreceptor characteristics of the image carrier.

  According to the present invention, the following effects can be obtained.

  (1) The amount of the actual lubricant on the surface of the image carrier is made constant by controlling the application of the developer based on the current value between the developer carrier and the image carrier in the development region. And high-quality images can be formed stably at all times.

  (2) By storing the reference current value in advance, the actual amount of lubricant on the surface of the image carrier can be matched with the optimum amount with simpler control.

  (3) By storing a plurality of reference current values corresponding to temperature and humidity conditions in advance, the actual amount of lubricant on the surface of the image carrier can be made to match the optimum amount more accurately. .

  (4) By storing a plurality of reference current values according to the rotation amount condition of the image carrier in advance, the actual amount of lubricant on the surface of the image carrier is more accurately matched with the optimum amount. be able to.

  (5) By judging the abnormality of the main body device from the detected current value, prohibiting the image forming operation, and displaying the abnormality, the user can be notified of the abnormality quickly.

  (6) By using a fatty acid metal salt as the lubricant, the function as the lubricant can be sufficiently exerted on the surface of the image carrier.

  Hereinafter, an image forming apparatus according to the best embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming unit provided in an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 forms a monochrome image based on image information received via a network (not shown). The image forming apparatus 100 includes a photosensitive drum 10, a charging device 20, an exposure device 30, a developing device 40, a transfer device 50, a lubricant applying unit 60, a cleaning device 70, and the like.

  The photosensitive drum 10 includes a cylindrical conductive base made of a nonmagnetic metal such as aluminum or a resin, a photosensitive layer formed on the surface of the cylinder, and the like, and is rotatably supported in the arrow Y direction. The charging device 2 uniformly negatively charges the surface of the photosensitive drum 10. As the charging device 2, for example, a contact charger such as a charging brush or a contact roller charger, or a non-contact charger such as a charging charger can be used. In this embodiment, a charging roller is used. The photosensitive drum 10 corresponds to the image carrier of the present invention, and the charging device 2 corresponds to the charging means of the present invention.

  The exposure device 30 forms an electrostatic latent image by exposing the charged surface of the photosensitive drum 10 with laser light. As the exposure apparatus 30, a laser scanning unit (LSU) having a semiconductor laser as a light source is used. The developing device 40 includes a developing roller 41, and performs development by supplying black toner contained therein to the electrostatic latent image on the photosensitive drum 1. In this embodiment, a one-component developing type developing device is used. The developing roller 41, which is a developing carrier of the present invention, is a developing region W that is in contact with a part of the surface of the photosensitive drum 41, and rotates the toner held on the peripheral surface while rotating in the arrow Z direction. Supply to the image. The developing roller 41 may have a configuration in which a gap is provided between the photosensitive drum 10 and a developing device that stores a two-component developer composed of toner and a carrier may be used.

  The transfer device 50 transfers the toner image formed on the surface of the photosensitive drum 10 at the transfer position onto a sheet supplied from a paper supply device (not shown). The cleaning device 70 includes a cleaning blade 71 corresponding to the cleaning means of the present invention, and removes and collects toner remaining on the surface of the photosensitive drum 10 after the transfer of the toner image onto the paper. The cleaning blade 71 contacts a part of the surface of the photosensitive drum 71 and removes remaining toner.

  The lubricant application means 60 includes a brush roller 61, a lubricant supply body 62, a cam 63, a motor 64, and the like, and is disposed inside the cleaning device 70. The brush roller 61 rotates in the arrow Y direction by driving a motor or the like (not shown), and applies a lubricant to the surface of the photosensitive drum 10 that is in contact with the brush roller 61. The brush roller 61 is grounded.

  The lubricant supply body 62 is supported by the support portion 62 </ b> A so as to be capable of reciprocating in the direction of the arrow X, which is the direction of contact with the brush roller 61, and supplies the lubricant when it contacts the brush roller 61. The support portion 62A is biased by a spring 62B in a direction away from the brush roller 61 in the arrow X direction. As the lubricant supply body 62, for example, there is a solid lubricant. In addition, there are sponges impregnated with a liquid lubricant.

  Lubricants include fluorine-containing resins, fatty acid metal salts, and the like that are preferably used from the standpoints of handling properties and physical properties, but fatty acid metal salts are preferred in view of the photoreceptor characteristics of the photoreceptor drum 10. As the fatty acid metal salt, metal salts such as palmitic acid, stearic acid, and oleic acid are preferable. As the metal to be bonded, zinc, calcium, aluminum or the like is preferable. Of these, zinc stearate and zinc palmitate are preferably used.

  The cam 63 contacts the surface of the support portion 62A opposite to the support surface of the lubricant supply body 61, and reciprocates the support portion 62A in the direction of the arrow X by rotation. Accordingly, the amount of contact of the lubricant supply body 62 with the brush roller 61 changes depending on the rotational position (rotation angle) of the cam 63, and the amount of lubricant applied to the surface of the photosensitive drum 10 by the brush roller 61 also changes. To do. That is, the amount of lubricant supplied to the photosensitive drum 10 is adjusted by the rotation angle of the cam 63.

  The motor 64 rotationally drives the cam 63. The drive of the motor 64 is controlled by the control unit 80 via the motor driver 65. The control unit 80 corresponds to the control unit of the present invention, and controls the operation of the entire image forming apparatus.

  FIG. 2 is a flowchart showing a procedure for controlling the rotation angle of the cam 63. The rotation angle of the cam 63 is periodically changed at a predetermined timing. The controller 80 starts an image forming process for a predetermined determination image at a predetermined timing (S1). Here, a solid image is used as the predetermined determination image. Next, a current value between the developing roller 41 and the photosensitive drum 10 in the developing region W where the developer image of the predetermined determination image is formed is acquired (S2). Specifically, as shown in FIG. 1, the current detection device 90 detects the current flowing from the detection member 91 that contacts the roller inner peripheral surface side of the photosensitive drum 10 in the development region W to the shaft core of the development roller 41. To do. The current detection device 90 outputs the detected detection result to the control unit 80. The current detection device 90 and the detection member 91 correspond to current detection means of the present invention.

  Thereafter, the control unit 80 reads the reference current value, the upper limit current value, and the lower limit current value from the storage unit 81 (S3), and determines whether or not the current value is not less than the lower limit current value and not more than the upper limit current value ( S4). When it is determined that the current value is less than the lower limit current value or greater than the upper limit current value, the control unit 80 determines that the main device is abnormal and displays a message notifying the main device of abnormality on the display device 85 such as a liquid crystal display. Then, the setting is made to prohibit image formation and the processing operation is terminated (S5). The display device 85 corresponds to display means of the present invention.

  On the other hand, when it is determined in the process of S4 that the current value is greater than or equal to the lower limit current value and less than or equal to the upper limit current value, the control unit 80 determines whether or not the current value is equal to the reference current value (S6). The reference current value is a target application amount indicating an appropriate amount of lubricant to be applied to the surface of the photosensitive drum 10, and the developing roller 41 and the photosensitive member in the developing region W when the lubricant is applied to the surface of the photosensitive drum 10. The current value between the drum 10 is shown. As the reference current value, a value obtained in advance by experiments is set. Details will be described later. Moreover, the value calculated | required by experiment with the reference current value is set also about the upper limit current value and the lower limit current value.

  If it is determined in step S6 that the current value is equal to the reference current value, the control unit 80 determines that the amount of lubricant actually applied to the surface of the photosensitive drum 10 is appropriate and performs the processing. finish. In addition, it is determined that the difference between the reference current value and the reference current value is about 10% of the reference current value is an error range and is equal.

  On the other hand, if it is determined in step S6 that the current value is not equal to the reference current value, the control unit 80 determines whether the current value is greater than the reference current value (S7). When determining that the current value is larger than the reference value, the control unit 80 rotates the cam 63 by a predetermined angle so that the lubricant supply body 62 is separated from the brush roller 61 from the current position (S8). The process returns to S1. As a result, the current amount of lubricant applied to the photosensitive drum 10 can be reduced. This is because when the detected current value is larger than the reference current value, the amount of lubricant applied to the surface of the photosensitive drum 10 is larger than the optimum amount.

  On the other hand, if it is determined in step S7 that the current value is smaller than the reference current value, the control unit 80 rotates the cam 63 by a predetermined angle so that the lubricant supply body 62 is closer to the brush roller 61 than the current position. (S9), the process returns to S1. As a result, the amount of lubricant applied to the current photosensitive drum 10 can be increased. This is because when the detected current value is smaller than the reference current value, the amount of the lubricant applied to the surface of the photosensitive drum 10 is less than the optimum amount.

  The predetermined angle may be, for example, the minimum angle at which the rotation of the cam 63 can be controlled, or any angle that can adjust the current value to be equal to the reference current value. Further, the transfer of the developer image of the predetermined determination image onto the paper is not performed.

  By repeatedly performing the cam rotation angle adjustment process described above, the detected current value can be made equal to the reference current value, and the amount of lubricant actually applied to the photosensitive drum 10 can be optimized. The amount can be matched, and a high-quality image can be formed stably at all times. In particular, the configuration using the contact-type charging device in which current easily leaks as in the present embodiment is highly effective because it can always maintain a coating amount that does not easily leak.

  The predetermined timing may be any time as long as image formation is not being performed, and may be, for example, every time a predetermined number of image formations are reached or every time a predetermined operation time elapses.

  FIG. 3 is a diagram showing the relationship between the amount of lubricant actually applied to the surface of the photoconductor drum 10 and the current value in the development region W of the photoconductor drum 10. 3 shows the surface potential (V0) of the photosensitive drum 10 = −650 (V), the surface potential (VL) of the photosensitive drum 10 after irradiation with light from the exposure device 30 = −100 (V), The surface potential of the developing roller (Vb) = − 350 (V), the development potential difference (ΔV) = VL−Vb = 250 (V), the ambient temperature of the photosensitive drum 10 = 20 ° C., and the ambient humidity = 60%. These are experimental results when image formation is performed using the above-described predetermined determination image.

  The amount of lubricant applied to the surface of the photosensitive drum 10 was consumed when the angle of the cam 63 was fixed under each experimental condition and an image was formed on 1000 sheets of A4 size paper using a predetermined determination image. The consumption weight per sheet of A4 size obtained from the consumption weight of the lubricant is shown as the coating amount (μg / sheet). The current value shown in FIG. 3 is an average value obtained by measuring the current between the developing roller 41 and the photosensitive drum 10 in every 100 sheets during the image formation of 1000 sheets of A4 size paper. is there. Measurement of the current for every 100 sheets is performed by sampling 10 points of current between the developing roller 41 and the photosensitive drum 10 in the developing region W while the latent image of the predetermined determination image is being developed. The average of the sampled current values is defined as a current value measured every 100 sheets. The above experiment was repeated by changing the angle of the cam 63 little by little, and the data shown in FIG. 3 was obtained.

  In the experiment, the image quality was confirmed by visually observing the paper on which the predetermined determination image was formed. As a result, the application amount of the lubricant was 20 to 100 μg / sheet. Therefore, in the image forming apparatus of the present embodiment, the optimum amount of lubricant applied to the surface of the photosensitive drum 10 is set to 60 μg / sheet, which is the median value of a good image quality range, and the corresponding current value of 1.167 μA is used as a reference. The current value was used.

  Further, the upper limit current value and the lower limit current value do not greatly deviate from the reference current value in a situation where the current value is actually adjusted to the reference current value, and do not exceed the range of the lower limit current value from these upper limit current values. If so, a value that can determine that the image forming apparatus has some abnormality is selected.

In the present embodiment, the upper limit current value and the lower limit current value are set to 1.545 μA and 0.788 A corresponding to 100 μg / sheet and 20 μg / sheet within a range in which the image quality is good.

  These current values are stored in the storage unit 81 in advance, and the process shown in FIG. 2 is executed at a predetermined timing.

  4 (A) to 4 (B) show development for coating amounts of 20, 60, and 100 μg / sheet when the experiment was performed under the same conditions as the experiment shown in FIG. 3 except that the temperature and humidity conditions were changed. The current value between the developing roller 41 and the photosensitive drum 10 in the region W is shown. 4A shows the results in a low temperature and low humidity (LL) environment, FIG. 4B shows the results in a normal temperature and normal humidity (NN) environment, and FIG. 4C shows the results in a high temperature and high humidity (HH) environment.

  As shown in FIG. 4, when the temperature and humidity change, the current value between the developing roller 41 and the photosensitive drum 10 in the developing region W also changes. Therefore, a plurality of reference current values, upper limit current values, and lower limit current values may be stored according to temperature and humidity conditions. For example, the experimental results of the present embodiment shown in FIGS. 4A to 4C are stored in the storage unit 81. A temperature sensor (not shown) and a humidity sensor (not shown) for detecting the temperature and humidity around the photosensitive drum 10 are provided, and the control unit 80 is detected by the temperature sensor and the humidity sensor in the process of S3 shown in FIG. A reference current value, an upper limit current value, and a lower limit current value of the temperature and humidity conditions that match the temperature value and the humidity value are read out, and the processes after S4 shown in FIG. 2 are performed.

  For example, in the process of S3 shown in FIG. 2, the temperature and humidity conditions that match after rounding the first place of the detected temperature value and humidity value are selected, and the reference current value and the like are read out. As a result, the actual amount of lubricant on the surface of the photosensitive drum 10 can be accurately made constant without being affected by changes in temperature and humidity. If the conditions do not match, the closest condition may be selected, for example. The temperature detection sensor and the humidity detection sensor correspond to the temperature detection means and the humidity detection means of the present invention.

  FIG. 5 shows the coating amounts of 20, 60, and 100 μg / sheet when the experiment was performed under the same conditions as the experiment shown in FIG. 3 except that the movement distance of the peripheral surface by the rotation of the photosensitive drum 10 was changed. The current value between the developing roller 41 and the photosensitive drum 10 in the developing region W is shown. Here, the moving distance of the peripheral surface indicates the total distance counted from the number of rotations actually rotated by the photosensitive drum 10 during image formation × the outer peripheral length, and corresponds to an integrated value of the number of rotations of the present invention.

  As shown in FIG. 6, the surface of the photoconductor drum 10 is scraped due to wear and the film thickness is reduced every time the rotation distance is increased, so that the capacitance (C) increases. Therefore, if the surface of the photosensitive drum 10 is maintained at a constant voltage (V), the accumulated charge (Q) increases, and the amount of electricity increases as shown in FIG. Incidentally, this corresponds to approximately 100,000 sheets of images formed at a distance of 60000 m.

  Therefore, the reference current value, the upper limit current value, and the lower limit current value may be stored according to the moving distance of the peripheral surface of the photosensitive drum 10. For example, the experimental result of this embodiment shown in FIG. In addition, a rotation sensor (not shown) that detects the number of rotations of the photosensitive drum 10 is provided, and the control unit 80 stores the movement distance of the peripheral surface calculated from the number of rotations and the outer peripheral length of the photosensitive drum in the storage unit 81. Keep it. The control unit 80 reads the reference current value, the upper limit current value, and the lower limit current value of the distance that matches (closest) to the read movement distance of the peripheral surface in the process of S3 shown in FIG. 2, and performs the process shown in FIG. Do. Thereby, the amount of the actual lubricant on the surface of the photosensitive drum 10 can be accurately made constant without being affected by the change of the moving distance and the degree of wear of the surface of the photosensitive drum 10. The rotation sensor corresponds to the rotation speed measuring means of the present invention.

  In this embodiment, the supply amount of the lubricant is adjusted by controlling the rotation angle of the cam 63. However, the present invention is not limited to this, and the lubricant supply body 62 is separated from the brush roller 61. It is also possible to control the timing time.

  For example, the storage unit 81 stores in advance a table that associates the difference value and the separation timing time in addition to the reference current value, the upper limit current value, and the lower limit current value. Set the timing time. First, at a predetermined timing, the control unit 80 starts an image forming process of a predetermined determination image in the same manner as the process of S1 shown in FIG. 2 (S11). Next, the current value between the developing roller 41 and the photosensitive drum 10 in the developing region W is acquired in the same manner as the processing of S2 shown in FIG. 2 (S12).

  Thereafter, the control unit 80 reads the reference current value, the upper limit current value, and the lower limit current value from the storage unit 81 in the same manner as the processes of S3 and S4 shown in FIG. 2 (S13), and the current value is equal to or greater than the lower limit current value. It is determined whether the value is equal to or less than the value (S14). When it is determined that the current value is less than the lower limit current value or greater than the upper limit current value, the control unit 80 displays a message notifying the abnormality of the main device on the display device 85 as in the process of S5 shown in FIG. The setting operation is prohibited and the processing operation is terminated (S15).

  On the other hand, if it is determined in step S14 that the current value is greater than or equal to the lower limit current value and less than or equal to the upper limit current value, the control unit 80 calculates the difference between the detected current value and the reference current value (S16). The separation timing time corresponding to the value is read and set (S17), and the process is terminated.

  Thereafter, at least during the image forming operation, the lubricant supply body 62 is separated from the brush roller 61 and the supply amount of the lubricant is adjusted at every elapse of the set separation / contact timing time.

  The reference current value may be set in consideration of both the temperature and humidity conditions and the moving distance.

  In the present embodiment, the image forming apparatus for monochrome images has been described, but the present invention can also be applied to an image forming apparatus for color images.

1 is a cross-sectional view illustrating a schematic configuration of an image forming unit provided in an image forming apparatus according to an embodiment of the present invention. It is a flowchart which shows the procedure which controls the rotation angle of a cam. 2 is a diagram illustrating a relationship between an amount actually applied to the surface of the photosensitive drum and a current value in a developing region of the photosensitive drum 10. FIG. 3 is a diagram illustrating a relationship between temperature and humidity conditions, an amount actually applied to the surface of the photosensitive drum, and a current value in a developing region of the photosensitive drum 10. FIG. 2 is a diagram illustrating a relationship between a moving distance of a peripheral surface due to rotation of the photosensitive drum, an amount actually applied to the surface of the photosensitive drum, and a current value in a developing region of the photosensitive drum 10. FIG. It is a figure which shows the relationship between the movement distance of the surrounding surface by rotation of a photoconductor drum, and the film thickness of the surface of a photoconductor drum. It is a flowchart which shows the procedure which controls the separation contact time to the brush roller of a lubricant supply body.

Explanation of symbols

10-photosensitive drum 20-charging device 41-developing roller 60-lubricant application unit 70-cleaning device 80-control unit 81-storage unit 90-current detection device 91-detection member

Claims (4)

An image carrier carrying a latent image on the surface;
Charging means for charging the surface of the image carrier;
A developer that supplies a developer to the latent image and forms a developer image on the surface of the image carrier in a development region that has a peripheral surface that abuts the surface of the image carrier or is opposed to the image carrier. A carrier;
Until the surface of the image bearing member reaches the charging unit through the transfer position for transferring the developer image onto the sheet, remove deposits on the surface of the image bearing member after application of or lubricants Cleaning means to
Until the surface of the image bearing member reaches said cleaning means through said transfer position, applying a fatty acid metal salt as the lubricant to the surface of the image bearing member after the transfer of the developer image Lubricant application means;
Development current detection means for detecting a current value between the developer carrier and the image carrier in the development region;
And control means for controlling the application amount of the lubricant by the lubricant applying means based on the current value detected by said developing current sensing means,
A current value between the developer carrying member and said image bearing member in the developing region when applied to the surface of the image bearing member and the lubricant of the proper amount to be applied to the surface of the image bearing member A storage unit for storing as a reference current value,
Wherein, the lubricant by the lubricant applying means depending on the current value detected by said developing current detector at the time of formation of the developer image of a predetermined determination image is greater or less than the reference current value images forming device you characterized by decreasing or increasing the coating amount of agent. Temperature detecting means for detecting the temperature around the image carrier;
Humidity detecting means for detecting the humidity around the image carrier, and
The reference current value includes a plurality of values corresponding to a plurality of temperature and humidity conditions,
The control means reads out the temperature value detected by the temperature detection means from the plurality of reference current values and the reference current value that matches the humidity value detected by the humidity detection means from the storage unit. The image forming apparatus according to claim 1, wherein: A rotational speed measuring means for measuring an integrated value of the rotational speed of the image carrier,
The reference current value includes a plurality of values corresponding to respective integrated values of a plurality of rotation speeds,
The image forming apparatus according to claim 1, wherein the control unit reads a reference current value that matches an integrated value of the rotation speed measured by the rotation speed measurement unit from the storage unit. Provided with display means for displaying the status of the main unit,
The storage unit stores an upper limit current value higher than the reference current value and a lower limit current value lower than the reference current value,
The control means determines the lubricant based on the difference between the current value and the reference current value when it is determined that the current value detected by the developing current detection means is not less than the lower limit current value and not more than the upper limit current value. An application unit is driven, and when it is determined that the current value is less than a lower limit current value or greater than an upper limit current value, an image forming operation is prohibited and an abnormal state of the main body device is displayed on the display unit. Item 2. The image forming apparatus according to Item 1.

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